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MANTOVANI, MARCO. "Nanoparticles for the removal of contaminants from wastewaters." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/305614.
Анотація:
Il presente lavoro di tesi si inserisce all’interno del progetto PerFORM WATER 2030 (Platform for Integrated Operation Research and Management of Public Water towards 2030), un progetto finanziato da regione Lombardia e dal Fondo Europeo di Sviluppo Regionale. L’elaborato ha l’obiettivo di produrre a scala di laboratorio delle nanoparticelle di ferro zero valente incapsulate in una matrice carboniosa (ME-nFe), un materiale con proprietà riducente ed elevato potere adsorbente da applicare nella depurazione delle acque. La sintesi delle nanoparticelle è avvenuta attraverso la carbonizzazione idrotermica (HTC) a partire da biomassa microalgale coltivata nell’impianto pilota situato presso il depuratore di Bresso-Niguarda (MI). Nello specifico, le prime fasi di lavoro si sono focalizzate sulla raccolta della biomassa direttamente in impianto e sulla sua caratterizzazione in termini di composizione elementare e contenuto di polifenoli. Successivamente si è passati allo studio delle condizioni che potessero influenzare la sintesi di CE-nZVI. Sono stati testati due tipi di sale da utilizzare quale fonte di ferro (solfato di ferro ammonico e nitrato di ferro), 4 rapporti Fe/C da inserire nel reattore (0.02, 0.05, 0.1, 0.2) e 3 temperature del processo di sintesi (180°C, 200°C e 225°C). Attraverso la caratterizzazione delle nanoparticelle ottenute in termini di contenuto di ferro zero-valente e ferro totale, di area superficiale specifica e di struttura morfologica a livello nanometrico, sono stati selezionati i prototipi dalle caratteristiche migliori. Le ME-nFE sono state testate nella rimozione di cinque metalli pesanti (Zn, Cu, Ni, Cd, Cr), prima in condizioni ideali e poi in condizioni più aderenti alla realtà. I migliori risultati sono stati ottenuti con una concentrazione di 3 gL-1 di adsorbente a partire da una concentrazione iniziale di ciascun metallo pari a 1 mgL-1. In queste condizioni si sono ottenute rimozioni per Zn, Cu, Ni e Cd superiori al 96%. Il Cr non è mai stato adeguatamente rimosso nei vari esprimenti. È stata inoltre valutata, a fine trattamento, la possibilità di recupero delle CE-nZVI e di un loro riutilizzo per più cicli di rimozione. In seguito, ci si è occupati della valutazione della tossicità del sottoprodotto liquido del processo HTC, sia nei confronti di Vibrio fisherii un batterio luminescente utilizzato come indicatore in ecotossicologia sia nei confronti delle stesse microalghe. Il test Microtox è stato effettuato sul refluo tal quale, individuando una forte tossicità anche su campioni assai diluiti (EC50= 1.8% dopo 15 minuti). Il test è stato ripetuto dopo strategie di pretrattamento (precipitazione del ferro attraverso modifica del pH) ma la tossicità era comunque elevata (EC50= 6.8%). Si è quindi valutato l’adsorbimento tramite carbone attivo (testando due concentrazioni 2 e 3gL-1). Entrambe le concentrazioni sono state in grado di ridurre sensibilmente la tossicità, con il risultato migliore portato dalla dose maggiore (EC50= 60% after 15 min). Infine, è stata valutata la possibilità di coltivazione delle microalghe su una diluizione del refluo HTC, al fine di studiare eventuali loro capacità di decontaminazione e al tempo stesso capire se fosse possibile chiudere il ciclo, valorizzando il sottoprodotto e ottenendo nuova biomassa per altre sintesi di CE-nZVI. Le microalghe sono state coltivate con successo su una miscela al 20% di centrato e sottoprodotto liquido, sia in batch che in continuo, aprendo scenari interessanti per rendere il processo di produzione della nanoparticelle più sostenibile.This thesis is part of PerFORM WATER 2030 (Platform for Integrated Operation Research and Management of Public Water towards 2030), a project financed by the Lombardy region and the European Regional Development Fund. The objective is to produce laboratory-scale zero valent iron nanoparticles encapsulated in a carbonaceous matrix (ME-nFe), a material with reducing properties and high adsorption capacity that can be used in wastewater treatment. The synthesis of the nanoparticles is achieved through hydrothermal carbonization (HTC) starting from microalgal biomass grown in the pilot plant located at the Bresso-Niguarda (MI) treatment plant. Specifically, the first phases of work focused on collecting biomass directly from the plant and on its characterization in terms of elemental composition and polyphenol content. Subsequently, the conditions that could influence the synthesis of ME-nFe were studied: two types of salt were tested as an iron source (ammonium iron sulphate and iron nitrate), four Fe/C ratios to be put in the reactor (0.02, 0.05, 0.1, 0.2) and three different temperatures of the synthesis process (180°C, 200°C and 225°C). The characterization of the produced nanoparticles in terms of zero-valent and total iron content, specific surface area and nanoscale morphological structure, allowed the selection of the prototypes with the best properties. Once the best operating conditions were identified, the ME-nFe were tested in the removal of five heavy metals (Zn, Cu, Ni, Cd, Cr), first under ideal conditions and then in more realistic ones. At the end of the treatment, the possibility of recovering the CE-nZVI and reusing it them for multiple removal cycles was also assessed. The best results were achieve using a sorbent concentration of 3 gL-1 on a starting solution of the five heavy metals with a starting concentration of 1 mg L-1. The removal for Zn, Cu, Ni e Cd were higher than 96%. However, Cr was never affected during the tests. Hereafter, the toxicity of the liquid by-product of the HTC process was studied, both towards Aliivibrio fischeri, a luminescent bacterium used as an indicator in ecotoxicology, and towards the microalgae themselves. Microtox Basic tests were performed on the raw liquid by-product, showing a very strong effect even on very diluted samples (EC50= 1.8% after 15 min). The test was than repeated after a pretreatment step (precipitation of dissolved iron after pH adjustment) but the final toxicity was still very high, proving that the problem was not the dissolved iron but probably the presence of some toxic organic compounds (EC50= 6.8% after 15 min). Adsorption with activated carbons (using two different adsorbent doses of 2 and 3gL-1) was then performed as an alternative pretreatment. Both concentrations were able to sensibly reduce the wastewater toxicity, with the best result achieved using the 3gL-1 dose (EC50= 60% after 15 min). Finally, the possibility of cultivating microalgae on a dilution of the HTC wastewater was assessed, in order to study their decontamination capacity and simultaneously evaluating the possibility of closing the cycle, enhancing the by-product and obtaining new biomass for other syntheses of CE-nZVI. Microalgae were grown on a 20% dilution of the liquid by-product using the centrate as the diluent, both in batch and continuous mode, making the process to produce the microalgal base nanoparticles more sustainable.
2
Ng, Dedy. "Nanoparticles removal in post-CMP (Chemical-Mechanical Polishing) cleaning." Thesis, Texas A&M University, 2005. http://hdl.handle.net/1969.1/4159.
Анотація:
Research was performed to study the particle adhesion on the wafer surface after the chemical-mechanical polishing (CMP) process. The embedded particles can be abrasive particles from the slurry, debris from pad material, and particles of film being polished. Different methods of particle removal mechanism were investigated in order to find out the most effective technique. In post-CMP cleaning, surfactant was added in the solution. Results were compared with cleaning without surfactant and showed that cleaning was more effective with the combined interaction of the mechanical effort from the brush sweeping and the chemistry of the surfactant in the solution (i.e., tribochemical interaction). Numerical analysis was also performed to predict the particle removal rate with the addition of surfactants. The van der Waals forces present in the wafer-particle interface were calculated in order to find the energy required to remove the particle. Finally, the adhesion process was studied by modeling the van der Waals force as a function of separation distance between the particle and the surface. The successful adaptation of elasticity theory to nanoparticle-surface interaction brought insight into CMP cleaning mechanisms. The model tells us that it is not always the case that as the separation distance is decreased, the attraction force will be increased. The force value estimated can be used for slurry design and CMP process estimation.
3
Zhai, Chunhao. "Polyimide Aerogels and Their Applications in Removal of Airborne Nanoparticles." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1464284202.
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Walrod, John Hamilton II. "ARSENIC REMOVAL WITH A DITHIOL LIGAND SUPPORTED ON MAGNETIC NANOPARTICLES." UKnowledge, 2017. http://uknowledge.uky.edu/chemistry_etds/83.
Анотація:
Exposure to arsenic (As) in water, the ubiquitous toxin that poses adverse health risks to tens of millions, is the result of both anthropogenic and geochemical mobilization. Despite recent publicity and an increased public awareness, the dangers associated with arsenic exposure rank among the top priorities of public health agencies globally. Existing sequestration applications mainly include reductions and adsorption with zero-valent metals and their oxides. The performance of adsorption media is known to preferentially favor aqueous As(V) over As(III) due to the charge of the dissolved oxyanion. Magnetic nanoparticles (MNP) have been the focus of multidisciplinary research efforts for the removal of aqueous toxic metals and metalloids since they can be magnetically separated from the treated water. This improves isolation and allows for regeneration of the MNP, reducing cost and resource consumption. This research is focused on As(III & V) sequestration through the use of synthetic ligands N,N’bis(2-mercaptoethyl)isophthalamide (abbreviated BDTH2) and 2,2’- (isophthaloybis(azanaediyl))bis-3-mercaptopropanoic acid (abbreviated ABDTH2). Additionally, As(III) sequestration with ABDTH2 functionalized on silica core-shell MNP (ABDTH2 MNP), magnetite MNP (ABDTH2@MNP), and commercial silica beads (ABDTH2 Si60) is demonstrated. Both BDTH2 and ABDTH2are effective precipitation agents for the removal of As(III) through the formation of S-As covalent bonds. ABDTH2MNP reduced a 200 ppb As(III) batch solution to below 10 ppb at pH 5,7, and 9. Additionally, complete removal was achieved in the presence of anions at concentrations of 200, 500, and 1000 ppb. This system was evaluated for the removal of total arsenic from industrial solutions accumulated during the production of renewable biogas in landfills. Direct precipitation with BDTH2 and ABDTH2 was inhibited by the complex matrix. However, batch removal with ABDTH2@MNP was effective in removing 82% of the inorganic arsenic. Sequestration of arsenic and speciation from these industrial solutions remains a challenge.
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Almeelbi, Talal Bakheet. "Phosphate Removal and Recovery Using Iron Nanoparticles and Iron Cross-Linked Biopolymer." Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26517.
Анотація:
Nanoscale zero-valent iron (NZVI) particles and iron cross-linked alginate (FCA) beads were successfully used for the first time for phosphate removal and recovery. NZVI was successfully used for phosphate removal and recovery. Batch studies indicated a removal of ~96 to 100% phosphate in 30 min (1, 5, and 10 mg PO43--P/L with 400 mg NZVI/L). Phosphate removal efficiency by NZVI was 13.9 times higher compared to Microscale ZVI (MZVI) particles. The successful rapid removal of phosphate by NZVI from aqueous solution is expected to have great ramification for cleaning up nutrient rich waters. The presence of sulfate, nitrate, and humic substances and the change in ionic strength in the water marginally affected phosphate removal by NZVI. A maximum phosphate recovery of ~78% was achieved in 30 min at pH 12.
Novel iron cross-linked alginate (FCA) beads were synthesized, characterized and used for phosphate removal. The beads removed up to 37-100% phosphate from aqueous solution in 24 h. Freundlich isotherm was found to most closely fit with experimental data and the maximum adsorption capacity was found to be 14.77 mg/g of dry beads. The presence of chloride, bicarbonate, sulfate, nitrate, and natural organic matters in aqueous solution did not interfere in phosphate removal by FCA beads. The phosphate removal efficacy FCA beads was not affected due to change in pH (4-9).
Nanosacle zero-valent iron (NZVI) and iron cross-linked alginate beads were also tested for phosphate removal using actual wastewater treatment plant effluent and animal feedlot runoff. The FCA beads could remove ~63% and ~77% phosphate from wastewater and feedlot runoff in 15 min, respectively.
Bioavailability of phosphate was examined using algae and higher plants. Phosphate and iron bioavailability of the NZVI sorbed phosphate was examined by supplying spent particles (NZVI with sorbed phosphate) to Tyee Spinach (Spinacia oleracea) and algae (Selenastrum capricornutum). Results revealed that the phosphate was bioavailable for both the algae and spinach. Also, presence of the nanoparticles enhanced the algae growth and plant growth and increases in biomass and plant length were observed. Iron (from spent NZVI) was found to be bioavailable for spinach.
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Seyedi, Seyed Mojtaba. "Engineered iron oxide nanoparticle-polymer composites for the removal of dissolved arsenic and antimony." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2017. https://ro.ecu.edu.au/theses/2038.
Анотація:
Dissolved metalloids, such as arsenic (As), antimony (Sb) and boron (B), are often found in contaminated surface waters or groundwater. Their removal is essential for protecting the water environment. This MEngSci research project investigated the use of magnetite (Fe3O4) nanoparticle – polymethylmethacrylate (PMMA) composites, as a reusable adsorbent toremove dissolved As andSb.
Comparative experiments were carried out to examine the effectiveness ofcommercial magnetite nanoparticles, lab synthesized nanoparticles, and the composites of synthesed Fe3O4nanoparticle-PMMA, for adsorbing As (III) and Sb (III) ions. The effects of major environmental and operating parameters (e.g. pH and adsorbent dosage) were investigated.Four cycles of adsorption-desorption experiment were conducted; the results demonstrating significant capability of the composites of removing the dissolved metalloids. In addition, the competitive adsorption of As and Sb to the composites was studied in batch experiments. It was found that the affinity of antimony to the adsorbents was generally greater than arsenic ions. A variety of analytical methods, such as X-Ray Diffraction (XRD), microwave plasma atomic emission spectrometry (MP-AES) and Malvern Zetasizer, were used to characterise the properties of the composites and analyze dissolved As and Sb concentrations. Details of the experimentalprocedures and results have been presented in this MEngSci thesis. Overall, this research validated: (a) a process to synthesize Fe3O4 nanoparticle-PMMA composites; and (b) the efficiency of using the composites to remove dissolved metalloids from contaminated water.
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Hu, Jing. "Fundamental investigation on removal and recovery of heavy metals from synthetic wastewater using magnetic nanoparticles /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?EVNG%202005%20HU.
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Farkas, Kata. "Mimicking virus removal and transport in aquifer media using surface-modified silica nanoparticles." Thesis, University of Canterbury. School of Biological Sciences, 2014. http://hdl.handle.net/10092/9349.
Анотація:
Contamination of drinking water sources, such as groundwater, by pathogens (protozoa, bacteria and viruses) is of major concern globally. Due to their small size, mobility and high infectivity, enteric viruses have been a focus of groundwater research. However, the behaviour of enteric viruses in aquifer media is still poorly understood, which is partially attributable to the lack of reliable surrogates for these viruses.
In the study reported in this thesis, a new type of surrogate was characterised and validated for its use in studying virus fate and transport in groundwater. The surrogates developed were composed of 70 nm carboxylated silica nanoparticles, labelled with dsDNA tags for sensitive detection, and coated with selected proteins to mimic the physico-chemical characteristics (size, charge, density) of two enteric viruses, human rotavirus and adenovirus, frequently found in faecal-contaminated groundwater. The selected enteric viruses and a commonly used virus surrogate, the MS2 bacteriophage, were purified and characterised in terms of size, surface charge, hydrophobicity and aggregation. For validation, the characteristics, the adsorption, degradation and transport of the surface-modified nanoparticles and the viruses were investigated in laboratory studies and compared.
The characterisation of the viruses and particles revealed that the modified silica nanoparticles resemble the size and negative surface charge of the rotavirus and adenovirus. In general, the nanoparticles were found to be less hydrophobic than the enteric viruses, thus presumably less interactive with hydrophobic media. In contrast, the MS2 bacteriophage was smaller in size than the enteric viruses studied and considerably more hydrophobic implying stronger interactions with hydrophobic media. The surface-modified nanoparticles were found to be more stable and remained more monodispersed over time than the purified enteric viruses.
In laboratory studies using simulated groundwater, the DNA-labelled nanoparticles were more stable over time than the rotavirus, the adenovirus or a plasmid DNA on its own. Interestingly, the study revealed that rotavirus was more persistent than the adenovirus over time in terms of degradation and aggregation, however, day light considerably enhanced rotavirus degradation.
The adsorption studies revealed strong interactions between the enteric viruses and natural aquifer media (gravel and sand), whereas most of the surface-modified nanoparticles adsorbed weakly to these media. Only the casein-coated nanoparticles adsorbed strongly to the sand. The MS2 adsorbed to the gravel strongly, but weakly to the sand implying different interactions. The studies on virus and nanoparticle adsorption to hydrophobic-coated and non-modified Ottawa sand supported the results of characterisation.
Column studies investigating the transport of the viruses and the nanoparticles in gravel and sand showed that even though gravel had high adsorption capacity in the adsorption tests, all viruses and nanoparticles travelled though the gravel columns with little retention, probably due to insufficient interaction time. This highlights the vulnerability of gravel aquifers to virus contamination. Experiments using sand columns showed great differences in the transport of the particles. Results suggested that the recovery of the DNA-labelled nanoparticles was similar to the recovery of the adenovirus, however, their transport pattern was different. The glycoprotein-, the protein A- and the AMBP-coated nanoparticles mimicked the transport pattern and low recovery of the rotavirus. In contrast, the streptavidin- and casein-coated nanoparticles were not recovered, emphasising the great importance of surface structure in particle transport.
The results of this study demonstrated the usefulness of protein-coated silica nanoparticles as virus surrogates in groundwater studies. Surface-modified nanoparticles are able to mimic the surface characteristics of viruses. The glycoprotein-, protein A- and AMBP-coated particles were found to be suitable surrogates for rotavirus, whereas the DNA-labelled nanoparticles resembled adenovirus behaviour in hydrophilic media. Using particles with different material, size and protein-coating other pathogens can be modelled as well. Furthermore, these particles are expected to besafe to humans and the environment, thus can be used in a great variety of experiments in environmental research.
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Verdugo, Gonzalez Brenda. "Regenerable Adsorbents for Removal of Arsenic from Contaminated Waters and Synthesis and Characterization of Multifunctional Magnetic Nanoparticles for Environmental and Biomedical Applications." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/202532.
Анотація:
The present work is divided into two sections. The first section deals with the synthesis of regenerable adsorbents for the removal of arsenic from contaminated waters. An adsorbent based on carboxymethylated polyethylenimine grafted agarose gels was synthesized and characterized as a regenerable synthetic ferric oxide adsorbent with high capacity for arsenate ions at pH 3.0. Similarly, four metal ion chelating adsorbents based on dipicolylamine were synthesized and characterized with respect to their Cu(II), Fe(III) and As(V) adsorption capacities. The most efficient adsorbents were Nov-PEI-DPA and Nov-TREN-DPA. Additionally, a commercial ion exchange resin was modified with permanganate to oxidize arsenite into arsenate. A complete oxidation-adsorption system was proposed in which a column packed with the oxidation resin was connected in series with an adsorbent column composed of the polyethylenimine grafted agarose gels.The second section involved work with magnetic nanoparticles. First, composite adsorbents consisting of magnetic particles encapsulated within agarose beads with and without grafted iminodiacetic acid (IDA) chelating groups were synthesized. The adsorption capacity of the adsorbents for Cu(II), Fe(III) and As(V) at different concentrations was investigated. Batch experiments were carried out to determine the Fe(III) and As(V) adsorption isotherms for the magnetic Novarose-IDA. Regenerability of the adsorbent was achieved with a pH change of the inlet solution, without affecting its magnetic or adsorption properties.Magnetic composite particles were synthesized for biomedical applications. First, magnetic nanoparticles were coated with silica and then used for gold nanoshell production. These nanoshells were functionalized with a Brij S10 derivative, containing carboxylic groups, using dodecanethiol as a bridging agent to incorporate a fluorescent biomolecule.Finally, magnetic and gold particles were encapsulated in PLGA nanoparticles. Docetaxel was loaded on these multifunctional nanoparticles and released studies were performed at 37°C. The presence of magnetite, colloidal gold and gold nanoshells in the PLGA nanoparticles was revealed by the coloration acquired by the polymeric nanoparticles. The release of drug from the polymeric nanoparticles showed a biphasic behavior with an initial burst followed by a prolonged slow release. There was no effect of the presence of magnetic or metallic particles on docetaxel release.
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Clarke, Emma Victoria Faye. "An investigation into silver nanoparticles removal from water during sand filtration and activated carbon adsorption." Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/29959.
Анотація:
Wastewater treatment plants (WwTP) act as the principle buffer between anthropogenic sources of Silver Nanoparticles (AgNPs) and environmental targets. AgNPs, given their effective anti-microbial properties, have the potential to negatively impact WwTP processes and organisms within the natural environment. A clear understanding of the fate and transport of AgNPs as they pass through WwTPs is crucial in evaluating AgNPs impacts for WwTP process, the natural environment and in the development of a comprehensive environmental risk assessment for AgNPs. The main aim of this thesis was to carry out an analysis on the fate, transport and transformation of AgNPs through WwTP relevant filtration medias in order to understand more about the toxicological implications for both WwTP processes and receiving environments. AgNPs were synthesised in-house, via an in-situ reduction method, which produced a homogeneous dispersion of nanoparticles of average particle diameter 9.98nm, with a standard deviation of 3.11nm. Column studies and adsorption isotherm experiments were conducted to investigate the fate and transport of silver nitrate, AgNPs and bulk silver across media beds of quartz sand and granulated activated carbon (GAC), both chosen for their relevance in wastewater treatment protocols. TEM imaging and EDS analysis was employed to characterise the AgNPs physically and elementally within the column influents and effluents. An original contribution made to the existing knowledge on AgNPs is that in contrast to bulk silver and silver nitrate, uncoated AgNPs were observed to be highly mobile through the quartz sand media. This high mobility was in contrast with the prior expectation that van der Waals forces of attraction between the positively charged AgNPs and the negative charge of the silica surfaces within the sand bed would lead to some measure of retention within the column matrix. The resulting high mobility of the AgNPs was attributed to particle surface contamination of boride ions originating from the reduction agent used during the synthesis process. This highlights (and reinforces) the importance of better understanding on the implications of the various methods of synthesis and use of capping agents for AgNPs characteristics and the impact this has on fate and transport. AgNPs were also noted to have been significantly altered after their passage through the quartz sand media, with up to 83% of the sample increasing in size, from 9.98nm to an average of 18.26nm and a maximum of 144nm. Particle size measurements were made using the measuring tool available in the GNU Image Manipulation Program (GIMP). This size increase was attributed to the formation of nano-alloy clusters with residual gold and iron compounds, naturally present within the sand bed. In the case of silver-gold alloy clusters, this is expected to exhibit positive implications for future environmental fates of the resulting AgNPs, where the presence of gold in alloy clusters has been observed to significantly deactivate AgNPs silver ion release. In contrast to the sand, it was observed that the GAC was an effective absorber of AgNPs. However, this was observed to be a size dependant relationship, where the GAC was not observed to be effective for adsorption of bulk silver at particle sizes of 300 – 800nm. In this thesis, in addition to the experimental work, a novel, low complexity technique was developed for the detection and quantification of AgNPs in laboratory aqueous solutions. This protocol utilises a laboratory bench top photometer and gave AgNPs concentration results that reliably and accurately reflected that of ICP-MS and ICP-OES results within a detection range of 0.01 and 20mg/L; where the correlation coefficient between the instrument absorbance response and ICP-MS/OES concentration (at 450nm) was R2 0.994.
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Cisse, Seydou. "Use of Biopolymer Entrapped Sulfate Reducing Bacteria and Metal Nanoparticles for Effective Aqueous Sulfate Removal." Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/27234.
Анотація:
Sulfate reducing bacteria (SRB) isolated from activated sludge were used to investigate sulfate removal from aqueous solution using calcium alginate entrapped SRB in batch studies with ethanol and lactose as the carbon sources. The interferences of pH, temperature, Al3+, Cu2+, and Zn2+ on sulfate removal were also investigated. Further, sulfate removal experiments were conducted with co-entrapped SRB and nanoscale zero-valent iron (NZVI) and separately entrapped SRB and NZVI. Results indicate that EntSRB can effectively remove sulfate from aqueous solution. 88-95% sulfate removal was achieved. Both ethanol and lactose worked well as carbon sources for entrapped bacteria. Interference studies indicated low sulfate removal in the presence of 25-50 mg/L of aluminum and zinc. Low pH (pH≤ 4) and low temperature (5?C) decreased sulfate reduction. NZVI appeared to have negative effects on SRB. Loading of 0.05 and 0.1 g of NZVI led to lower SO42- removal as compared to experiments without NZVI.Fulbright Program Fellowship
National Science Foundation (NSF, Grant: CCMI-1125674)
12
Gomez-Rivera, Francisco. "Exploration of Biological Treatment Systems for the Removal of Persistent Landfill Leachate Contaminants and Nanoparticles." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/145311.
Анотація:
The integrity of groundwater sources is constantly threatened by contaminant plumes generated by accidental gasoline leakages and leachates escaping landfills. These plumes are of concern due to their proven toxicity to living organisms. Aromatic and chlorinated hydrocarbons, volatile fatty acids, phenols, and ammonia have been found in these leachates. In addition, benzene, toluene, and xylenes (BTX) are major components of gasoline. The lack of oxygen in groundwater makes anaerobic bioremediation desired for the treatment of groundwater contaminated with BTX and chlorinated solvents. With the objective of finding microorganisms capable of BTX and cis-dichloroethylene (cis-DCE) degradation under anaerobic conditions for their use in permeable reactive barriers, different inocula were tested in batch experiments. Toluene was rapidly degraded by several inocula in the presence of alternative electron acceptors. Benzene and m-xylene were eliminated by few of the inocula tested after incubation periods ranging from 244 to 716 days. cis-DCE was highly recalcitrant as no degradation was observed over 440 days. Biological processes have been successfully applied for the treatment of landfill leachates as well. In an effort to provide an effective and economical alternative, an anaerobic-aerobic system was evaluated using a synthetic media simulating the organic and ammonia content of real leachates. The removal of the organic content reached 98% in an upflow anaerobic sludge blanket reactor, and resulted in the formation of methane. During the aerobic process, in an innovative down-flow sponge reactor, ammonia was highly transformed to nitrite and nitrate. Complete nitrification was eventually achieved.The capacity of current wastewater treatment plants for removing nanoparticles has been questioned during the last years. Nanoparticles have been incorporated into numerous applications and their presence in wastewater seems to be inevitable. A laboratory-scale secondary treatment system was set-in to study the behavior of cerium and aluminum oxide nanoparticles during wastewater treatment. The nanoparticles were highly removed, suggesting that secondary treatment is suitable for their elimination. The removal of these nanoparticles was influenced by the pH and organic content of the wastewater. Aluminum nanoparticles proved to be toxic; however the performance of the system for eliminating the organic content was recovered over time.
13
Rottman, Jeffrey J. "Fundamentals and Application of Porous Media Filtration for the Removal of Nanoparticles from Industrial Wastewater." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/255157.
Анотація:
Increasing use of engineered nanomaterials presents concerns as some nanoparticles appear to be harmful to both human health and the environment. Effective treatment methods are required to remove problematic nanoparticles from (waste)water streams. Porous media filtration, commonly used for the removal of particulate matter, shows promise for nanoparticle treatment. The goal of this work is to investigate the potential of porous media filtration for the abatement of nanoparticles from aqueous waste streams. To this end, an automated method was developed that allows real-time and in-situ monitoring of nanoparticle transport and retention in porous media using online measurement of UV-visible absorbance or fluorescence. Development of fluorescent-core nano-silica (n-SiO₂) in controllable sizes provided an excellent tracer for nanoparticle transport in porous media. Measurement of n-SiO₂ by destructive techniques is complicated by high natural Si background levels. Fluorescence monitoring enables real-time measurement, facilitating rapid evaluation of n-SiO₂ transport. Synthesized n-SiO₂ remain in their primary sizes making an evaluation of the behavioral change of particles due to transition into the "nano" range possible. A comparison of the role of particle size on transport in porous media displayed the importance of particle number concentration as the dominance of site-specific adsorption may be obscured by simple mass concentration evaluation.T he effectiveness of different bed materials, namely, sand, activated carbon (AC), and diatomaceous earth (DE), for the removal of TiO₂ nanoparticles (n-TiO₂) from aqueous streams was investigated. DE proved promising for n-TiO₂ capture shown by its high bed capacity (33.8 mg TiO₂ g⁻¹(medium)) compared to AC (0.23 mg TiO₂ g⁻¹(medium)) or sand (0.004 mg TiO₂ g⁻¹(medium)). The presence of organic and synthetic contaminants produced varying effects on n-TiO₂ retention, mostly due to either enhanced electrostatic or steric interactions. Application of a process simulator combining physical straining with site-specific interactions, delineating physisorption from chemisorption and diffusion limited interactions, enabled the accurate fit of n-TiO₂ transport in sand, AC and DE. The fitting process revealed the advantage of DE due to increased physisorption and physical straining of n-TiO₂. Modeling of this system afforded the elucidation of controlling retention mechanisms and provides a basis for future scaling and system design.
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Kumar, Rajender. "Development and potential applications of nanomaterials for arsenic removal from contaminated groundwater." Thesis, KTH, Miljögeokemi och ekoteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96106.
Анотація:
In this study, a magnetic nanomaterial was used for the binding of anionic arsenic species from contaminated groundwater. Iron oxide (Fe3O4) magnetic nanoparticles (NPs) and the surface modified Fe3O4 NPs with 3-aminopropyl-triethoxysilane (3-APTES), Trisodium citrare (TSC) and Chitosan were synthesized with the co-precipitation method. Structural characterizations showed that the four kinds of NPs had different sizes an average particle range size of 15-20 nm was observed with Transmission Electron Microscopy. X-ray diffraction was used to identify the crystalline structure of synthesized Fe3O4 and surface modified NPs. Molecular structure and functional groups present in synthesized magnetic NPs Fe3O4 were identify with infrared analysis. The synthesized Fe3O4 NPs and surface coated NPs were used for determine the binding capacity of Arsenic ions from the synthetic groundwater. The binding of As(III) increased as the dissolved As(III) concentration increased in the solution. From the experiments it was found chitosan-coated NPs are best than other coated and uncoated NPs for arsenite removal from the solution. It was found that if only As(III) ions were present in the water without other anions and cations the binding capacity of the magnetic NPs is very high. The binding capacity of As ions was decreased with presence of other anions and cations in the groundwater because they interfere with arsenic binding sites which presence on the magnetic NPs.
15
Martinson, Carol A. "Evaluation of cupric oxide (CuO) nanoparticles in the removal of arsenic species from groundwater across a wide range of natural conditions." Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594490421&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Molinari, Simone. "Chromium and arsenic removal from contaminated water: environmental application of maghemitenanoparticles (samns)." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3424791.
Анотація:
Arsenic (AsIII-V) and Chromium (CrVI) are carcinogenic when inhaled or ingested with drinking water, they are classified as class A human carcinogen. As consequence the World Health Organization (WHO) fixed the threshold limit in drinking water at 10 µg l-1 for As and 50 μg l-1 for total Cr. The reduction of their concentration in wastewater is of great importance. Conventional remediation methods consist in chemical reduction, adsorption and anion exchange. They are strongly affected by high operational costs, large use of reagents and secondary problems of sludge generation with potential hazards of landfill leaching. Low-cost and sustainable techniques must be identified as alternatives or to implement conventional treatment methods. Nanoparticles are one of the most promising sustainable technique thanks to the opportunity of minimizing ex-situ activities, improve selectivity and subsurface remediation efficiency. The research project is focused on the application of superparamagnetic maghemite nanoparticles called SAMNs (Surface-Active Maghemite Nanoparticles) for the removal of toxic metals (As and CrVI) from groundwater aiming at minimizing ex-situ activities, increase remediation efficiency and achieve a better binding selectivity accomplishing the growing request of green and sustainable remediation. SAMNs are characterized by high colloidal stability and the ability to selectively bind CrVI, As and other macromolecules due to the topography of undercoordinated FeIII sites on their surface. The compendium of characteristics, spanning from the synthesis carried out in water, the surface reactivity and specificity and the biocompatibility make SAMNs an interesting candidate for large scale remediation processes. Results highlighted that SAMNs is an ideal low-cost material for ex situ and in situ remediation by As and CrVI. The removal efficiency of SAMNs for AsIII-V and CrVI was proved with variable testing conditions in terms of variable SAMNs and pollutant concentrations, pH of the solution. Moreover, results of kinetic and thermodynamic studies, coupled with a deep structural and chemical characterization of SAMN@metal complexes substantiate the occurrence of different and complex binding mechanisms, hence revealing specific binding processes on SAMNs surface. SAMNs can remediate high concentrations of CrVI (22 mg L-1) in water with a strong pH dependence, moreover test toward CrVI removal on real polluted samples from the Ex-Stoppani site with CrVI concentrations in the 0.5-19 mg L-1 range, confirmed SAMNs great potential for the exploitation to a large-scale industrial level. Results confirm SAMNs high adsorption efficiency (>80% of CrVI removed) found even at neutral to basic pH values, typical conditions of groundwater. At the same time, no particular interfering anions were found. For arsenic, besides substantiating the ability of SAMNs to sequestrate it at completion, a different binding affinity of the two As species (AsIII and AsV) is shown. The maximum binding capacity of SAMNs toward AsIII (~24 mg g-1) resulted constant in the whole pH range explored, while for AsV binding (~32 mg g-1 at pH 3.0) a rapid decrement with pH was observed. Moreover, the study of the interaction of SAMNs with AsIII-V by X-ray photoelectron spectroscopy revealed a correlation between the binding specificity, the modification of lattice oxygen and the restoration of surface crystallinity. These superficial reactions were attributed to the surface topography of under-coordinated FeIII sites.
Even if nanosized iron oxide were deeply studied, the present thesis besides enriching the knowledge on iron oxides, open the door to new synthetic approaches to investigate new opportunities from metal oxide materials. Novel syntheses can lead to nanomaterials characterized by smart surfaces, offering novel and promising features which can be very useful for a wide range of applications, from water remediation to biotechnology.L'arsenico (AsIII-V) e cromo (CrVI) sono classificati come cancerogeni di classe A se inalati o ingeriti con acqua. l'Organizzazione Mondiale della sanità (OMS) ha fissato come limite nelle acque per l’As 10 µg l-1 e 50 µg l-1 per il Cr. La riduzione della loro concentrazione è quindi di vitale importanza. I metodi di bonifica convenzionali sono basati su riduzione chimica, adsorbimento e scambio di anioni. Essi sono influenzati da elevati costi, uso di grandi quantità di reagenti e generazione di fanghi con potenziali pericoli di lisciviazione in discarica. Tecniche a basso costo e sostenibili devono essere identificate come alternative o per implementare i metodi di trattamento convenzionali. Le nanoparticelle sono una delle tecniche più promettenti per ridurre le attività ex situ, migliorare la selettività e l'efficienza di bonifica del sottosuolo. Il progetto di ricerca si basa sull'applicazione di nanoparticelle superparamagnetiche di maghemite chiamate SAMNs (Surface Active Maghemite Nanoparticles) per la rimozione di metalli tossici (As e CrVI) dalle acque, con l'obiettivo di ridurre le attività ex situ, aumentare l'efficienza di bonifica e ottenere un migliore selettività per soddisfare la crescente domanda di bonifiche sostenibili. Le SAMNs sono caratterizzate da un'elevata stabilità colloidale e dalla capacità di legare selettivamente CrVI, As e altre macromolecole a causa della topografia dei siti di FeIII non coordinati sulla superficie. Il compendio di caratteristiche, dalla sintesi in acqua, la reattività superficiale, la specificità e biocompatibilità, rendono le SAMNs un promettente candidato per la bonifica a larga scala. I risultati hanno evidenziato che le SAMNs sono un materiale ideale a basso costo per la bonifica ex situ e in situ di As e CrVI. L'efficienza di rimozione è stata dimostrata con variabili concentrazioni di SAMNs ed inquinanti, pH della soluzione. Inoltre, i risultati di studi cinetici e termodinamici, associati ad una dettagliata caratterizzazione strutturale e chimica dei complessi SAMN@metallo, hanno confermato l'insorgenza di diversi e complessi meccanismi di legame, rivelando specifici processi superficiali. Le SAMNs possono rimuovere alte concentrazioni di CrVI (22 mg L-1) in acqua con una forte dipendenza dal pH; inoltre i test per la rimozione di CrVI su campioni reali dal sito Ex-Stoppani con concentrazioni nell'intervallo 0,5-19 mg L-1 di CrVI, hanno mostrato un grande potenziale per applicazioni a larga scala su livello industriale. I risultati hanno confermato l'elevata efficienza di adsorbimento delle SAMNs (>80% di CrVI rimosso) riscontrata anche a valori di pH neutri, condizioni tipiche delle acque sotterranee. Allo stesso tempo, non sono stati trovati anioni interferenti. Per l'arsenico, oltre a dimostrare la capacità di sequestramento fino alla totale rimozione, è stato trovata una diversa affinità di legame delle due specie AsIII e AsV. La massima capacità di legame per l’AsIII (~ 24 mg g-1) risulta costante in tutto il range di pH investigato, mentre per l’AsV (~32 mg g-1 a pH 3,0) è stato osservato un rapido decremento con pH. Lo studio dell'interazione delle SAMNs con AsIII-V mediante spettroscopia fotoelettronica a raggi X ha rivelato una correlazione tra la specificità di legame, modifica degli ossigeni strutturali e ripristino della cristallinità superficiale. Queste reazioni superficiali sono attribuite alla topografia superficiale dei siti FeIII non coordinati. Anche se le nanoparticelle di ossido di ferro sono state a fondo investigate, la presente tesi, oltre ad arricchirne la conoscenza, apre le porte a nuovi approcci di sintesi per investigare nuove opportunità dagli ossidi di ferro. Nuove sintesi possono portare a nanomateriali caratterizzati da peculiari caratteristiche superficiali, offrendo novità e caratteristiche promettenti che possono essere molto utili per una vasta gamma di applicazioni, dalla bonifica dell'acqua alla biotecnologia.
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Calderón, Roca Blanca. "Application of iron-based nanostructures to contaminant remediation." Doctoral thesis, Universidad de Alicante, 2017. http://hdl.handle.net/10045/69809.
Анотація:
This thesis focuses on the synthesis and applications of nanoscale zero valent iron (nZVI) in the environmental remediation of contaminants. The polyvalent characteristics of this nanomaterial are evaluated in this work with the study of its application in a wide range of contaminants: heavy metals and pesticides in water medium, and malodorous sulfur compounds present in air streams. Moreover, a novel method of synthesis of encapsulated nZVI from a waste material is presented, which meets the principles of green chemistry and at the same time represents a low-cost method of obtaining nZVI with improved characteristics. Chapter 1 describes the current state of the topics that will be discussed in the rest of the thesis. Specifically, the different mechanisms of contaminant remediation by nZVI are discussed, a summary of the current synthesis methods is presented and the principal modifications of nZVI to improve its characteristics are described. Finally, the limitations of the current techniques are assessed, which will be the starting point of the thesis. In Chapter 2, the application of nZVI to heavy metal removal during long time periods is explored. The contaminants studied are Zn, Cd, Ni, Cu and Cr, which are the most common heavy metals found in ground and wastewater. A delivery-effect of the heavy metal ions that had already been attached to nZVI surface is observed after long reaction times, which is a consequence of the nZVI aging and oxidation. The conditions that influence the delivery-effect are assessed and possible solutions to this detected problem are presented. In Chapter 3, nZVI is applied to the removal of sulfur-based odorous compounds in air streams. The compounds studied are hydrogen sulfide and dimethyl disulfide (DMDS), which are commonly found in wastewater treatment plants. Both nZVI loading and pH are varied to assess their influence on the process. Bimetallic nanoscale particles of Cu/Fe, Ni/Fe and Pd/Fe are synthesized in order to improve the DMDS abatement by the nZVI. The advantages of this new method for odor removal are discussed at the look of the experimental results. Lastly, a pilot scale test was performed in a wastewater treatment plant in order to test the effectiveness of the nZVI in a real application. The nZVI were applied in a scrubber to eliminate the sulfurous compounds from the pre-treatment area of the wastewater treatment plant. Chapter 4 deals with the application of nZVI to the oxidation of non-biodegradable pollutants by the Fenton reaction. Specifically, the effect of pH on the degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is studied. The advantages of using nZVI as a Fenton reagent compared to homogeneous Fenton are described. Furthermore, the addition of UV-light to the process is investigated. Finally, the main degradation intermediates of the reaction are identified and a degradation mechanism is accordingly proposed. In Chapter 5, the presence of polychlorinated dioxins and furans (PCDD/Fs) in the nZVI surface is addressed. Studies have shown that nZVI enhances the formation of such chlorinated compounds during thermal processes, but it is unclear which the origin of the compounds is. It has been suggested that nZVI could possess impurities such as PCDD/Fs in its surface. Therefore, the concentration of PCDD/Fs in both commercial and laboratory-synthesized nanoparticles is analyzed. PCDD/Fs pattern and WHO-TEQ concentrations are also obtained. As an outcome of the results obtained in this chapter, a recommendation for preventing the PCDD/Fs presence in nZVI is given. Chapter 6 is dedicated to the synthesis of carbon-encapsulated nanoparticles using hydrothermal carbonization (HTC) of an agricultural waste, particularly, olive mill wastewater (OMW). This novel method, in addition to meet the green chemistry principles, makes profit of the high polyphenol content of OMW to maximize the fraction of incorporated iron into the nZVI. Moreover, the carbon layer surrounding the nZVI protects it against oxidation and avoids its aggregation. Several HTC conditions are explored to study their implications in the characteristics of the material obtained. A deep characterization of the encapsulated nZVI is also presented in this chapter. In Chapter 7, the applications of the encapsulated nZVI synthesized in Chapter 6 are explored and compared for the same contaminants that have been studied in the previous chapters. Then, the advantages of encapsulated nZVI in comparison with common nZVI are discussed at the end of the chapter, and an estimation of the synthesis costs with this method is addressed. Lastly, in Chapter 8, the main conclusions of the thesis are summarized and suggestions for future work are presented.
18
Al, Anazi Abdulaziz H. "Synthesis of Recyclable Magnetic Metal-ferrite Nanoparticles for the Removal of Contaminants of Emerging Concern in Water." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1543922143864275.
19
Barrabés, Rabanal Noelia. "Selective Hydrogenation Catalysts For Environmental Processes: Nitrate And Chlorocompounds Removal." Doctoral thesis, Universitat Rovira i Virgili, 2009. http://hdl.handle.net/10803/8573.
Анотація:
En el presente trabajo se han diseñado, sintetizado y caracterizado catalizadores heterogéneos. Se ha estudiado la actividad y selectividad, de estos materiales, en el tratamiento de compuestos que comportan problemas medioambientales. Para la preparación de los catalizadores se han utilizado diferentes técnicas tales como impregnación, proceso redox y combustión. A su vez, se han sintetizado nanopartículas metálicas, depositándolas en diferentes materiales y testado su actividad catalítica. La actividad de estos catalizadores se ha comparado con catalizadores comunes en diferentes procesos. Por otro lado, se han utilizado diferentes materiales, alumina, carbón activo, ceria e hidrotalcitas, con el propósito de estudiar el efecto del soporte.La contaminación por nitratos en las aguas subterráneas es un problema importante en determinadas regiones. Esta problemática ha impulsado el estudio de la eliminación catalítica de los nitratos, en la que se enfoca la primera parte de la tesis. Este estudio se realizó en un reactor en continuo de lecho fijo. Se sintetizaron, caracterizaron y ensayaron, varios catalizadores monometálicos, bimetálicos y de nanopartículas soportadas. Una vez determinada la actividad y la estabilidad de los catalizadores se procedió a optimizar los materiales con el fin de mejorar la selectividad de éstos hacia nitrógeno. El presente trabajo ha sido el punto de partida para la puesta en marcha de una planta piloto para el tratamiento de aguas subterráneas reales contaminadas con nitratos. Próximamente será inaugurada una planta de eliminación catalítica de nitratos de aguas subterráneas con capacidad 500m3/día en las proximidades de El Morell (Tarragona).
La segunda parte de la tesis se enfoca en el proceso de hidrodecloración catalítica de compuestos orgánicos clorados como el tricloroetileno. Los experimentos se llevaron a cabo en fase gas utilizando diferentes tipos de catalizadores, los cuales fueron sintetizados y caracterizados. Se emplearon diferentes catalizadores, mono y bimetálicos, para la transformación del tricloroetileno a un producto de valor añadido, como es el etileno.
El presente trabajo, además de aportar conocimientos fundamentales en la catálisis heterogénea, contribuye a forjar soluciones a problemas medioambientales reales que afectan a la salud humana.
In the present study have been designed, synthesised and characterised heterogeneous catalysts. Their activities and selectivity have been studied in the treatment of compounds that present environmental problems. For the catalysts preparation different protocols such as incipient-wetness impregnation, co-impregnation, redox and combustion have been followed. In addition, metal nanoparticles were synthesized and deposited on several materials as well as tested their catalytic behaviour. The activity and the selectivity of nanoparticle catalysts with that of other catalysts in different processes were compared. On the other hand, different materials such as alumina, active carbon, ceria and hydrotalcites were used to study the role of them as catalyst supports.
In the light of the current demand for drinking water, the first part of this thesis studies the catalytic hydrogenation of nitrates. The study is carried out in a fixed bed continuous reactor. Several bimetallic, monometallic and supported nanoparticle catalysts have been synthesised, characterized and tested in order to improve their activity and stability and to optimise their selectivity to nitrogen. The present study was further extended and some of the catalysts have been used as a starting point for a Pilot Plant investigation into eliminating nitrate in real ground water. At this moment, a plant is being constructed in the vicinity of El Morell, Tarragona, which can use catalysis to reduce nitrates in 500 m3/day of groundwater.
The second part of the thesis deals with the catalytic hydrodechlorination of chlorinated organic compounds such as TCE. The experiments were done in gas phase. Different types of catalysts have been synthesised, characterized and tested and the final objective is to obtain an active and stable catalyst that is selective toward valuable products such as ethylene.
This research aims to use catalytic technologies to contribute to solving real environmental problems that affect human life.
20
JASPER, ANTHONY JOHN. "Impact of Nanoparticles and Natural Organic Matter on the Removal of Organic Pollutants by Activated Carbon Adsorption." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1218743967.
21
Salih, Hafiz H. M. "The Implications of Nanoparticles on the Removal of Volatile Organic Compounds from Drinking Water by Activated Carbon." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321366798.
22
Meduri, Kavita. "Carbon-Supported Transition Metal Nanoparticles for Catalytic and Electromagnetic Applications." Thesis, Portland State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10933285.
Анотація:
Recently, there has been growing interest in using transition metals (TM) for catalytic and electromagnetic applications, due to the ability of TMs to form stable compounds in multiple oxidation states. In this research, the focus has been on the synthesis and characterization of carbon-supported TM nanoparticles (NPs), specifically palladium (Pd) and gold (Au) NPs, for catalytic applications, and transition metal oxides (TMO) NPs, specifically Fe3O4 NPs for electromagnetic applications. Carbon supports have several advantages, such as enabling even distribution of particles, offering large specific surface area with excellent electron conductivity, and relative chemical inertness.
In this dissertation, for catalytic applications, emphasis was on removal of trichloroethylene (TCE) from groundwater. For this application, carbon-supported Pd/Au NP catalysts were developed. Pd was chosen because it is more active, stable and selective for desired end-products, and Au has shown to be a good promotor of Pd’s catalytic activity. Often, commercially available Pd-based catalysts are made using harsh chemicals, which can be harmful to the environment. Here, an environmentally friendly process with aspects of green chemistry was developed to produce carbon-supported Pd/Au NP catalysts. This process uses a combination of sonochemistry and solvothermal syntheses. The carefully designed carbon-supported Pd/Au NP catalyst material was systematically characterized, tested against TCE, and optimized for increased rate of removal of TCE. Electron microscopy and spectroscopy techniques were used to study the material including structure, configuration and oxidative state. The Pd/Au NPs were found mainly to form clusters with an aggregate-PdShellAuCore structure. Using state-of-the-art direct detection with electron energy loss spectroscopy, the Pd NPs were found to have an oxidative state of zero (0). The formation of the catalyst material was studied in detail by varying several synthesis parameters including type of solvent, sonication time, synthesis temperature etc. The most optimized catalyst was found remove TCE at double the rate of corresponding commercial Pd-based catalysts in a hydrogen headspace. This material was found to catalyze the removal of TCE via traditional hydrodehalogenation and shows promise for the removal of other contaminants such as trichloropropane (TCP), carbon tetrachloride (CT).
This green approach to make and optimize TM materials for specific applications was extended to TMOs, specifically magnetite (Fe3O4) and further developed for the application of electromagnetism. As catalysts, Fe3O4 is used for removal of p-nitrophenol from water. However, since the carbon-supported Pd/Au material system was developed and optimized for catalysis, here, carbon-supported Fe3O 4 NPs were developed for electromagnetic applications. There has been growing interest in tuning the magnetic properties of materials at room temperature with the use of external electric fields, for long-term applications in data storage and spintronic devices. While a complete reversible change of material properties has not yet been achieved, some success in partial switching has been achieved using multiferroic spinel structures such as Fe3O 4. These materials experience a change in magnetic moment at room temperature when exposed to the electric fields generated by electrochemical cells such as lithium ion batteries (LIBs) and supercapacitors (SC). In the past, a 1% reversible change was observed in Fe3O4 using LIBs. Here, building on the developments from previous material system, Fe 3O4 NPs were directly hybridized onto the graphene support in order to increase the observable change in magnetic moment. The material was systematically designed and tested for this application, including a study of the material formation. A simple, environmentally friendly synthesis using the solvothermal process was implemented to make the graphene-supported Fe 3O4 NPs. This new material was found to produce a reversible change of up to 18% in a LIB. In order to overcome some of the difficulties of testing with a LIB, a corresponding hybrid SC was designed, built and calibrated. The graphene-supported Fe3O4 NPs were found to produce a net 2% reversibility in the SC, which has not been reported before. The results from both the LIB and SC were analyzed to better understand the mechanism of switching in a spinel ferrite such as Fe3O4, which can help optimize the material for future applications.
The focus of this dissertation was on the development of a methodology for carbon-supported TM and TMO NPs for specific applications. It is envisioned that this approach and strategy will contribute towards the future optimization of similar material systems for a multitude of applications.
23
Eduok, Samuel. "Evaluation of the impact of engineered nanoparticles on the operation of wastewater treatment plant." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8261.
Анотація:
The effect of engineered nanoparticles (ENPs) mixture consisting of silver oxide, (Agg0[Silver Oxide Nanopartical], 20 nm), titanium dioxide, (TiO2[Titanium dioxide], 30-40 nm) and zinc oxide, (ZnO, 20 nm) compared with their bulk metal salts was evaluated against unspiked activated sludge (control) using 3 parallel pilot-scale treatment plants. The total concentration of the ionic species of Ag+ Ti[Silver + Titanium] and Zn(2+) in the effluent of the ENP spiked activated sludge (AS) was below limits of detection and> 99% of the spiked ENP were found in the waste activated sludge (WAS), whereas 39 – 58 % of Ag0[Silver Oxide Nanopartical], 51 – 63 % and 58 – 74 % of ZnO ion concentrations were recovered in the anaerobic digestate (AD) cake suggesting higher affinity of ENPs to WAS than to anaerobic digestate. ENPs induced a 2-fold increase of the microbial community specific oxygen uptake rate (SOUR) compared with the control and > 98 % of ammonia and 80 % of COD were removed from the AS suggesting that the heterotrophic biomass retained their ability to nitrify and degrade organic matter at the spiked ENP concentration. The floc size and cultivable microbial abundance was reduced in the ENP spiked AS with no apparent disruption of the overall AS process efficiency. However, scanning electron microscopic analysis clearly showed damage to specific microbial cells. The lipid fingerprint and 16S rRNA gene-based pyrosequencing evidenced the dominance of Proteobacteria, Firmicutes, and Bacteriodetes with a clear temporal shift in microbial community structure. The prominent nano-tolerant bacterial species identified were Acidovorax, Rhodoferax, and Comamonas whereas Methanocorpusculum and Methanosarcina were recovered in AS and were the dominant Archaea in the AD with 99 and 98 % similarities to the closest culturable relative. Their presence in the AS suggests tolerance to ENPs and oxygen-dependent respiration. V. fisheri activity was not sensitive to the ionic concentrations of the ENP or metal salt mixture in the digestate samples and illustrates the need to develop bioassay using indigenous wastewater microorganisms to detect the potential effect of ENP. Overall, unlike other xenobiotic compounds, ENPs can hasten the natural selection of microbial species in activated sludge and anaerobic digestion processes.
24
Pretorius, Chantelle. "Covalent immobilisation of β-Galactosidase from Escherichia coli to commercially available magnetic nanoparticles for the removal of lactose from milk". Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71958.
Анотація:
Thesis (MSc)--Stellenbosch University, 2012.ENGLISH ABSTRACT: ß-Galactosidase of Escherichia coli is the equivalent of lactase in humans and has the ability to bind and hydrolyse lactose. Lactase de ciency is a common phenomenon present in almost 70% of the world's population. This has resulted in greater than before demands on the food processing industry to develop a method that will allow for the hydrolysis of the disaccharide lactose in milk but will also allow for the removal of the remaining active enzyme. In this thesis, a new method, that is bio-speci c and well characterized for the removal of lactose from a lactose containing solution, is described. The E537D mutated version of ß-Galactosidase, which has a much lower activity compared to the wildtype and is able to bio-speci cally bind lactose for longer periods, was covalently immobilised to commercially available magnetic nanoparticles (fl uidMAG-Amine) via two coupling strategies. Glutaraldehyde is a cross-linking agent that reacts with amine groups, while N- (3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) is a coupling agent that activates carboxylic groups. These agents are widely used for the coupling of biomolecules to solid supports. The covalently coupled fluidMAG-E537D ß-Galactosidase particles were characterized regarding retained enzymatic activity and ability to bind and physically remove lactose from a lactose containing solution by applying an external magnetic eld, after lactose binding, to the enzyme-particle complex in solution. Each component aimed at yielding this functionally immobilised enzyme complex was studied and optimized to contribute to the development of this novel technique, which is a ordable and simple, for the removal of lactose from solution for the ultimate production of lactose free milk. Results indicated the glutaraldehyde method of ß-Gal cross-linking to fluidMAG-Amine to be the preferred strategy since it allowed an increased carrier capacity of protein to the particles. The glutaraldehyde cross-linked protein also exhibited a two-fold higher activity than the EDC coupled protein. Furthermore, the glutaraldehyde cross-linked fluidMAG-E537D ß-Gal was able to physically remove 34 % of the lactose from a 0.2 nmol/L lactose in solution. This, therefore, con rmed the potential use of this novel technique in the food processing industry.
AFRIKAANSE OPSOMMING: ß-Galaktosidase vanaf Escherichia coli is dieselfde as laktase in mense en beskik oor die vermoë om laktose te bind en te hidroliseer. 'n Gebrek aan laktase kom algemeen voor en ongeveer 70 % van die wêreldbevolking ly hieraan. Laasgenoemde het daartoe gelei dat daar meer druk as vantevore op die voedselproduksie industrie is om 'n metode te ontwikkel waarmee die hidrolise van die disakkaried laktose in melk moontlik sal wees asook die verwydering van die oorblywende aktiewe ensiem. In hierdie tesis word 'n nuwe metode beskryf wat biospesi ek en goed gekarakteriseer is vir die verwydering van laktose vanuit 'n laktose bevattende oplossing. Die E537D gemuteerde weergawe van ß-Galaktosidase, wat beskik oor 'n baie laer aktiwiteit as die wildetipe asook die vermoë om laktose biospesi ek vir langer periodes te bind, is kovalent geïmmobiliseer op kommersieel beskikbare magnetiese nanopartikels (fluidMAG-Amine) via twee koppelingsstrategieë. Glutaraldehied is 'n kruisbindingsagent wat met amino groepe reageer, terwyl EDC 'n koppelingsagent is wat karboksie groepe aktiveer. Hierdie agente word algemeen gebruik vir die binding van biomolekules aan soliede matrikse. Die kovalent gekoppelde fluidMAG-E537D ß-Galaktosidase partikels is gekarakteriseer met betrekking tot behoue ensimatiese aktiwiteit en vermoë om laktose te bind en sies te verwyder vanuit 'n oplossing wat laktose bevat deur 'n eksterne magneetveld op die ensiem-partikel kompleks in oplossing toe te pas, nadat die binding van laktose plaasgevind het. Elke komponent van hierdie funksioneel geïmmobiliseerde ensiemkomplekse is ondersoek en geoptimaliseer met die doel om by te dra tot die ontwikkeling van 'n nuwe tegniek wat bekostigbaar en eenvoudig is vir die verwydering van laktose vanuit 'n oplossing vir die uiteindelike gebruik in die produksie van laktose-vrye melk. Resultate het getoon dat die glutaraldehied metode van ß-Gal kruisbinding op fluidMAG-Amine verkies word aangesien dit 'n verhoogde draerkapasiteit van proteïene op die partikels moontlik maak. Die glutaraldehied gekoppelde proteïene beskik ook oor twee keer meer aktiwiteit as die EDC gekoppelde proteïene. Die glutaraldehied gekoppelde fluidMAG-E537D ß -Gal kon 34 % van die laktose teenwoordig in 'n 0.2 nmol/L laktose oplossing sies verwyder. Hierdie het dus die potensiële gebruik van hierdie nuwe metode in die voedselproduksie industrie bevestig.
25
Lallart, Adeline. "Ultra propreté : des microgouttes aux nanoparticules." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAY019/document.
Анотація:
Avec l’évolution de la microélectronique et la miniaturisation des différents composants à l’échelle nanométrique, la taille des particules critiques à éliminer lors du procédé de fabrication a été drastiquement réduite. En effet, cette taille critique est actuellement de l’ordre de 10nm. Les procédés de nettoyage doivent donc être capables de retirer ces particules sans endommager les surfaces. Afin de répondre à ce challenge, deux méthodes sont étudiées dans ce travail : l’utilisation d’un spray et l’application conjointe d’une couche de polymère et d’un spray.Le spray est utilisé depuis de nombreuses années dans le domaine de la microélectronique. Cependant, le mécanisme de détachement des particules par cette méthode n’est toujours pas assimilé. Le but de cette étude est de mieux le comprendre. Ainsi, différents paramètres vont être étudiés aboutissant à l’élaboration d’un modèle de détachement, faisant apparaître de nouvelles variables liées au procédé de nettoyage, à la contamination (nature et taille des particules) ou encore aux conditions de stockage des surfaces.De son côté, le procédé par utilisation conjointe de couche polymère et de spray est en plein essor mais peu d’informations sont aujourd’hui disponibles. Néanmoins de premières études ont démontré sa capacité à nettoyer des surfaces présentant des motifs et son efficacité quel que soit la taille de la contamination. Dans ce travail, différents procédés de retrait de la couche polymère seront comparés ainsi que certaines propriétés physico-chimiques propres à celle-ci. L’objectif étant de déceler des paramètres clefs influençant le retrait particulaire et de proposer une prémisse d’élucidation des mécanismes physiques mis en jeuWith the evolution of microelectronics and the miniaturization of the various components at the nanoscale, the size of the critical particles to be removed during the manufacturing process has been drastically reduced. Indeed, this critical size is currently of the order of 10 nm. Cleaning processes must therefore be able to remove these particles without surfaces damage. In order to answer this challenge, two methods are studied in this work: the use of a spray and the joint application of a polymer layer and a spray.The spray has been used for many years in the microelectronics field. However, the mechanism of particles detachment by this method is still not assimilated. The purpose of this study is to better understand it. Thus, different parameters will be studied leading to the development of a detachment model, showing new variables related to the cleaning process, contamination (nature and particle size) or the storage conditions of surfaces.For its part, the process by using a combination of polymer layer and spray is in full development, but little information is available today. Nevertheless, early studies have demonstrated its ability to clean surfaces with patterns and its effectiveness regardless of the size of the contamination. In this work, different methods of the polymer layer removal will be compared as well as some physicochemical properties specific to it. The objective is to detect key parameters influencing particle removal and to propose a premise of elucidation of the physical mechanisms involved
26
Vaughan, Lisa Ann. "Enviromentally benign synthesis and application of some spinel ferrite nanopartilces." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/44876.
Анотація:
In this thesis, the commercial viability of the aminolytic synthesis method is explored through robustness, versatility, and waste reduction studies. We report the preparation of metal precursors and the development of a synthetic approach using an aminolytic reaction of metal carboxylates in oleylamine and non-coordinating solvent. Manganese doping in the cobalt ferrites allows for the investigation of the couplings. All the compositions in the series Co1-xMnxFe2O4, 0.0 x 1.0 were synthesized via the aminolytic reaction. The coercivity decreases with increasing Mn2+ concentration due to reducing of high magnetic anisotropy ion (Co2+) content. To our knowledge, this work is the first completed series of Co1-xMnxFe2O4. The method is used to synthesize manganese ferrites dope with chromium. This allows for the investigation of the effects of orbital momentum quantum coupling. All the compositions of MnFe2-xCrxO4, x= 0.0, 0.05, 0.13, 0.25, 0.43, 0.62, and 0.85, were synthesized via the In-situ aminolytic method. Chromium concentration weakens the couplings resulting in the decrease in overall magnetic moment. All by-products can be recycled for re-utilization. The "mother" solution can be used for multiple batches without treatment. Our trials have shown that the reaction could undergo ten reactions using the same solution without scarifying the quality or yield of the product. Finally, an environmental application is explored through the use of iron oxides. Samples of goethite, maghemite, magnetite, and hematite were synthesized and characterized. These nanoparticles were exposed to arsenic and chromium solutions to measure the percent uptake of contaminant by each phase. Adsorption isotherms were plotted to obtain Freundlich parameters. The adsorption constant (K) averages over a 400% increase on literature values. We synthesized hematite and maghemite core-shell particles and exposed them to arsenite and maghemite core-shell particles have the higher removal affinity due to their smaller size.
27
Westphal, Emily Nicole. "Lignin-Magnetite Nanoparticles Aiding in Pickering Emulsions and Oil Manipulation and Their Rheological Properties." University of Dayton / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1619710097550949.
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Busse, Marta Julia. "Bionanocomposites of Fe3O4/SiO2 and alginate for magnetic removal of Cr(III) species from water." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14196.
Анотація:
Mestrado em QuímicaThe aim of the present work was to study the removal of Cr (III) species from aqueous solutions by adsorption process, using magnetic nanoparticles functionalized with amine groups and with the polysaccharide alginate. Heavy metal pollution is serious environmental and public health problem worldwide. Chromium is one of the most toxic metal endangering human life. Cr(III) is often used in industry which caused water pollution. Therefore, increased interest by the researchers to employ nanomaterials for the removal contamination and explore adsorbents to replace expensive materials, particularly low-cost raw materials such as, residual polymers materials or agricultural by-products. The work included the preparation of magnetic nanoparticles, coating them with amorphous silica shell functionalized with amine groups and the covalent attachment of alginate to the magnetic nanoparticle. The properties of the nanoparticles were assessed by a number of experimental techniques namely x-ray diffraction, infrared spectroscopy, elemental analysis, thermogravimetry and zeta potential measurements. Silica coated magnetic nanoparticles functionalized with amine groups were investigated for the uptake of Cr(III)/EDTA complexes from water, while the nanoparticles attached to the alginate molecules were tested for the removal of aqueous Cr(III) ions. The kinetic results were fitted to models of pseudo first and pseudo second order and the equilibrium adsorption results were adjusted to suitable isotherm models such as Langmuir and Freundlich. The composite nanoparticles revealed affinity to the Cr(III) species. Due to its properties, this new composite nanoparticles may find interesting applications in purification of water.
O objectivo do presente trabalho foi o de estudar a eliminação de Cr (III), a partir de soluções aquosas, por processo de adsorção, utilizando nanopartículas magnéticas funcionalizadas com grupos amina e com o polissacarídeo alginato. A poluição causada por metais pesados está na base de graves problemas de saúde pública e ambientais em todo o mundo. O crómio é um dos metais mais tóxicos, pondo em perigo a vida humana. O Cr (III) é frequentemente usado na indústria, causando a poluição da água. Por esta razão, aumentou o interesse dos investigadores na utilização de nanomateriais para a remoção de poluentes e no estudo de adsorventes para substituir materiais caros, nomeadamente matérias-primas de baixo custo, tais como, materiais provenientes de polímeros residuais ou subprodutos agrícolas. Este trabalho incluiu a preparação de nanopartículas magnéticas, o seu revestimento com uma capa de sílica amorfa funcionalizada com grupos de amina e a ligação covalente do alginato à nanopartícula magnética. As propriedades das nanopartículas foram avaliadas utilizando várias técnicas experimentais nomeadamente difracção de raios-X, espectroscopia de infravermelho, análise elementar, termogravimetria e medições do potencial zeta. As nanopartículas magnéticas revestidas com sílica e funcionalizadas com grupos de amina foram investigadas para a adsorção de Cr (III) / complexos de EDTA de águas, enquanto que as nanopartículas ligadas às moléculas de alginato foram testadas para a remoção de iões Cr (III) em meio aquoso. Os resultados de cinética foram ajustados aos modelos de pseudo-primeira e pseudo-segunda ordem, e os resultados de equilíbrio de adsorção foram ajustados aos modelos adequados, tais como a isotérmica de Langmuir e a de Freundlich. As nanopartículas compósitas revelaram ter afinidade para as espécies de Cr (III). Devido às suas propriedades, estas nova nanopartículas compósitas podem encontrar aplicações interessantes na purificação de águas.
29
Lee, Jung Ju. "Removal of Microcystin-LR from Drinking Water Using Adsorption and Membrane Processes." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1229026536.
30
Cordier, Marie. "Outdoor bronze conservation: assessment of protective treatments by accelerated aging and of treatment removal procedures by laser cleaning." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/5731/.
Анотація:
Outdoor bronzes exposed to the environment form naturally a layer called patina, which may be able to protect the metallic substrate. However, since the last century, with the appearance of acid rains, a strong change in the nature and properties of the copper based patinas occurred [1]. Studies and general observations have established that bronze corrosion patinas created by acid rain are not only disfiguring in terms of loss of detail and homogeneity, but are also unstable [2]. The unstable patina is partially leached away by rainwater. This leaching is represented by green streaking on bronze monuments [3]. Because of the instability of the patina, conservation techniques are usually required.
On a bronze object exposed to the outdoor environment, there are different actions of the rainfall and other atmospheric agents as a function of the monument shape. In fact, we recognize sheltered and unsheltered areas as regards exposure to rainwater [4]. As a consequence of these different actions, two main patina types are formed on monuments exposed to the outdoor environment. These patinas have different electrochemical, morphological and compositional characteristics [1]. In the case of sheltered areas, the patina contains mainly copper products, stratified above a layer strongly enriched in insoluble Sn oxides, located at the interface with the uncorroded metal. Moreover, different colors of the patina result from the exposure geometry. The surface color may be pale green for unsheltered areas, and green and mat black for sheltered areas [4]. Thus, in real outdoor bronze monuments, the corrosion behavior is strongly influenced by the exposure geometry. This must be taken into account when designing conservation procedures, since the patina is in most cases the support on which corrosion inhibitors are applied.
Presently, for protecting outdoor bronzes against atmospheric corrosion, inhibitors and protective treatments are used. BTA and its derivatives, which are the most common inhibitors used for copper and its alloy, were found to be toxic for the environment and human health [5, 6]. Moreover, it has been demonstrated that BTA is efficient when applied on bare copper but not as efficient when applied on bare bronze [7]. Thus it was necessary to find alternative compounds. Silane-based inhibitors (already successfully tested on copper and other metallic substrates [8]), were taken into consideration as a non-toxic, environmentally friendly alternative to BTA derivatives for bronze protection.
The purpose of this thesis was based on the assessment of the efficiency of a selected compound, to protect the bronze against corrosion, which is the 3-mercapto-propyl-trimethoxy-silane (PropS-SH). It was selected thanks to the collaboration with the Corrosion Studies Centre “Aldo Daccò” at the Università di Ferrara. Since previous studies [9, 10, 11] demonstrated that the addition of nanoparticles to silane-based inhibitors leads to an increase of the protective efficiency, we also wanted to evaluate the influence of the addition of CeO2, La2O3, TiO2 nanoparticles on the protective efficiency of 3-mercapto-propyl-trimethoxy-silane, applied on pre-patinated bronze surfaces. This study is the first section of the thesis.
Since restorers have to work on patinated bronzes and not on bare metal (except for contemporary art), it is important to be able to recreate the patina, under laboratory conditions, either in sheltered or unsheltered conditions to test the coating and to obtain reliable results. Therefore, at the University of Bologna, different devices have been designed to simulate the real outdoor conditions and to create a patina which is representative of real application conditions of inhibitor or protective treatments. In particular, accelerated ageing devices by wet & dry (simulating the action of stagnant rain in sheltered areas [12]) and by dropping (simulating the leaching action of the rain in unsheltered areas [1]) tests were used.
In the present work, we used the dropping test as a method to produce pre-patinated bronze surfaces for the application of a candidate inhibitor as well as for evaluating its protective efficiency on aged bronze (unsheltered areas).
In this thesis, gilded bronzes were also studied. When they are exposed to the outside environment, a corrosion phenomenon appears which is due to the electrochemical couple gold/copper where copper is the anode. In the presence of an electrolyte, this phenomenon results in the formation of corrosion products than will cause a blistering of the gold (or a break-up and loss of the film in some cases). Moreover, because of the diffusion of the copper salts to the surface, aggregates and a greenish film will be formed on the surface of the sample [13].
By coating gilded samples with PropS-SH and PropS-SH containing nano-particles and carrying out accelerated ageing by the dropping test, a discussion is possible on the effectiveness of this coating, either with nano-particles or not, against the corrosion process. This part is the section 2 of this thesis.
Finally, a discussion about laser treatment aiming at the assessment of reversibility/re-applicability of the PropS-SH coating can be found in section 3 of this thesis. Because the protective layer loses its efficiency with time, it is necessary to find a way of removing the silane layer, before applying a new one on the “bare” patina. One request is to minimize the damages that a laser treatment would create on the patina. Therefore, different laser fluences (energy/surface) were applied on the sample surface during the treatment process in order to find the best range of fluence. In particular, we made a characterization of surfaces before and after removal of PropS-SH (applied on a naturally patinated surface, and subsequently aged by natural exposure) with laser methods. The laser removal treatment was done by the CNR Institute of Applied Physics “Nello Carrara” of Sesto Fiorentino in Florence.
In all the three sections of the thesis, a range of non-destructive spectroscopic methods (Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), μ-Raman spectroscopy, X-Ray diffractometry (XRD)) were used for characterizing the corroded surfaces. AAS (Atomic Absorption Spectroscopy) was used to analyze the ageing solutions from the dropping test in sections 1 and 2.
31
Morrill, Samuel. "Combined Metal-Enhanced Fluorescence-Surface Acoustic Wave (MEF-SAW) Biosensor." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5081.
Анотація:
Immunofluorescence assays are capable of both detecting the amount of a protein and the location of the protein within a cell or tissue section. Unfortunately, the traditional technique is not capable of detecting concentrations on the nanoscale. Also, the technique suffers from non-specific attachment, which can cause false-positives, as well as photobleaching when detecting lower concentrations is attempted. There is also a time constraint problem since the technique can take from many hours to a few days in some cases.
In this work, metal-enhanced fluorescence (MEF) is used to lower the detection limit and reduce photobleaching. Unfortunately, MEF also increases the intensity of non-specifically bound proteins (NSBPs). Therefore, a surface acoustic wave (SAW) device is used to remove the more weakly bound NSBPs. Previously, this has been shown on lithium niobate, but it is used with a quartz substrate in this work. The SAW device is also used to cause micro-mixing which speeds the process up significantly.
In this research, it was found that silver nanocubes can lower the detection limit down to below 1 ng/mL. Quartz SAW devices are shown to remove NSBPs at a power of 10 mW applied for five minutes. Micro-mixing is shown to be improved by a factor of six at 10 mW for 10 minutes by saturating the antibody used in this research, which takes 1 hour without micro-mixing. Finally, all three components are combined. In this work, the whole device is used to detect 50 ng/mL. After micro-mixing, the intensity is the same as with MEF, and, after removal, it has been lowered by 7 a.u.
32
Xu, Yinhui Zhao Dongye. "Removal of copper(II) and lead(II) from soils by poly(amidoamine) dendrimers and reductive immobilization of chromium(VI) by stabilized zero-valent iron nanoparticles." Auburn, Ala., 2006. http://repo.lib.auburn.edu/Send%208-7-07/XU_YINHUI_21.pdf.
33
Mercadier, Thomas. "Retrait particulaire par étalement et retrait d’un film de résine." Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALT095.
Анотація:
Les étapes de retrait de la contamination particulaire sont cruciales pour l’industrie de la microélectronique afin de maximiser le pourcentage de circuit intégré fonctionnel en fin de fabrication. Cependant, les techniques conventionnelles de retrait particulaire peuvent s’avérer incompatibles avec des structures complexes et fragiles car leur application peut potentiellement causer des dommages physiques. Un procédé innovant basé sur l’étalement temporaire d’un film de résine est étudié dans ce manuscrit. Le principe est fondé sur le décollement du film de résine qui entraine le retrait de la particule en raison des liaisons de surface les reliant. Dans notre cas, la résine utilisée est composée de deux polymères organiques immiscibles. Le procédé consiste en l’étalement de la résine par centrifugation puis en son décollement par une distribution d’ammoniaque dilué à température ambiante. Cette distribution a pour but de dissoudre l’un des deux polymères ce qui provoque la délamination puis le soulèvement du film de résine grâce aux forces de trainée et de portance.Ce manuscrit souligne le rôle de l’organisation des deux polymères non miscibles dans le décollement du film de résine. Cette organisation dépend notamment de l’énergie de surface du substrat. Par exemple il a été montré par des analyses Tof SIMS que le polymère soluble présente une forte affinité avec une surface hydrophile. Une telle organisation sur une surface hydrophile réduit la zone interfaciale devant être délaminée lors de la dispense d’ammoniaque. Par conséquent, le décollement dépend de l’énergie de surface du substrat et n’est réalisable que si elle est supérieure à 66mN/m.Cette organisation spécifique des deux polymères immiscibles peut être ajustée par des paramètres tels que le ratio de mélange ou l’épaisseur de la résine. L’influence de l’ajout d’une étape de recuit après l’étalement a aussi été étudiée. Il a été démontré que ces trois paramètres modifiaient la limite en énergie de surface du décollement du film de résine. Ces paramètres influencent aussi l’efficacité du procédé dans le retrait particulaire. Les mécanismes à l’origine de ces modifications ont été compris permettant l’optimisation du procédé. Ce procédé optimisé a été évalué sur des surfaces structurées. Les résultats ont démontré sa capacité à retirer efficacement des particules tout en préservant l’intégrité des structures.Ces travaux de thèse ont permis de comprendre les mécanismes à l’origine du retrait particulaire à l’aide d’un procédé utilisant le décollement d’une résine et de démontrer la pertinence de cette technique dans un contexte industrielEfficient particle contamination removal is crucial in maximizing yield within the microelectronics industry. However, conventional particle removal techniques may become impractical when dealing with complex and fragile surface structures, as their application can potentially cause physical damage. This challenge has led to the development of new cleaning processes based on innovative concepts, such as a resist film lift off approach. The resist film lift-off leads to the particle removal due to the particle surface bonded to the resist. One of these particle removal processes is studied in this manuscript. In this process, the resist film is composed of two immiscible organic polymers. The process consists of the resist spin-coating followed by a diluted ammonia dispense at room temperature. Thanks to the latter chemical step, one of the polymers is dissolved inducing the delamination and lift-off of the remaining polymer with drag and lift forces.This manuscript sheds light on the critical role of the organization of two immiscible polymers within the resist film in the context of film lift-off. The organization of these polymers was shown to depend on the substrate surface energy through Tof SIMS analysis. For instance, on a hydrophilic substrate, the soluble polymer exhibits a pronounced affinity for the interface. Such an organization on hydrophilic surface minimizes the interfacial area that needs to be delaminated during the resist removal step. Consequently, the effectiveness of ammonia-based film removal relies on the substrate’s surface energy and is only achievable if the substrate surface energy is below 66mN/m.This manuscript provides valuable insights into the modification of the polymers’ organization. The tuning of some parameters from the resist formulation as the blend ratio or the resist thickness and the addition of a bake after the coating are shown to modify this surface energy peeling limit. Additionally, a Particle Removal Efficiency study was conducted on blanket wafers to determine and understand how these three parameters influence cleaning efficiency. It has led to the optimization of process efficiency. This optimized process efficiency was evaluated on structured surfaces. The results showcased its capability to efficiently remove particles while preserving the integrity of delicate structures.This PhD project has contributed to broadening the comprehension of particle removal using a resist peeling process. Moreover, it has demonstrated the potential application of this method in an industrial context
34
Ezzatahmadi, Naeim. "Synthesis and characterisation of mineral based composite materials for the remediation of contaminated aqueous solutions." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/131822/1/Naeim%20Ezzatahmadi%20Thesis.pdf.
Анотація:
Expanding urbanisation and industrialisation have increased aqueous concentrations of organic contaminants which are toxic to human health and the environment. Hence, remediation of these contaminants from aqueous solutions has become an important environmental concern. This research project aims to synthesize novel mineral-based composite materials, namely diatomite/Fe/Ni, palygorskite/Fe/Ni and sepiolite/Fe/Ni and study their applications for the removal of Orange II and 2,4-dichlorophenol from water. Experimental investigations contain material characterization, batch removal experiments, kinetic studies and contaminant removal mechanisms. Finally, complete removal of the contaminants showed promise of these composite materials for the treatment of organic contaminants from aqueous solutions.
35
Shanbhogue, Sai Sharanya. "Alginate Encapsulated Nanoparticle-Microorganism System for Trichloroethylene Remediation." Thesis, North Dakota State University, 2012. https://hdl.handle.net/10365/26675.
Анотація:
Nanoscale zero-valent iron (NZVI) particles were encapsulated in calcium alginate capsules for application in environmental remediation. TCE degradation rates for encapsulated and bare NZVI were similar indicating no adverse effects of encapsulation on degradation kinetics. Microorganisms were separately encapsulated and used along with encapsulated NZVI and co-encapsulated in calcium alginate capsules. Batch experiments were performed to test the efficacy of the combined iron-Pseudomonas sp. (PpF1) system. The combined system removed 100% TCE over the first three hours of the experiment followed by 70% TCE removal post TCE re-dosing. Complete reduction of TCE was achieved by NZVI between 0-3 h and the second phase of treatment (3-36 h) was mostly achieved by microorganisms. Experiments conducted with co-encapsulated NZVI-D.BAV1 achieved 100% TCE removal. During the first three hours of the experiment 100% TCE removal was achieved by NZVI, and 100% removal was achieved post re-dosing where D.BAV1 accomplished the treatment.Department of Civil Engineering, North Dakota State University
36
Gustafsson, Olof. "Nanoparticle Removal and Brownian Diffusion by Virus Removal Filters: Theoretical and Experimental Study." Thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-335802.
Анотація:
This study aims to examine the throughput of nanoparticles through a Cladophora cellulose based virus removal filter. The effect of Brownian motion and flow velocity on the retention of 5 nm gold nanoparticles, 12.8 nm dextran nanoparticles and 28 nm ΦX174 bacteriophages was examined through MATLAB simulations and filtration experiments. Modeling of Brownian motion at different flow velocities was performed in MATLAB by solving the Langevin equation for particle position and velocity for all three types of particles. The motion of all three particle types was shown to be constrained at local flow velocities of 1∙10-2 m/s or greater. The constraint was greatest for ΦX174 bacteriophages, followed by dextran particles and then gold particles as a result of particle diameter. To verify the effect experimentally, virus removal filters were prepared with a peak pore width of 23 nm. Filtration experiments were performed at different flux values where gold and dextran particles did not exhibit any difference in retention between fluxes. However, a significant amount of gold and dextran particles were removed by the filter despite being smaller than the measured pore size. A decrease in retention with filtrated volume was observed for both particle types. Filtration of ΦX174 bacteriophages exhibited a difference in retention at different fluxes, where all bacteriophages where removed at a higher flux. The results from both simulations and experiments suggest that the retentive mechanism in filtering is more complex than what can be described only by size exclusion sieving, Brownian diffusion and hydrodynamic constraint of particles.
37
Oliveira, Fernanda Gandra de. "S?ntese e caracteriza??o do comp?sito ferro zero-valente nanoparticulado/carv?o ativado granulado (nFZV-CAG) e sua aplica??o para remo??o do f?rmaco nimesulida pelos processos adsor??o/redu??o e ozoniza??o catal?tica heterog?nea." UFVJM, 2016. http://acervo.ufvjm.edu.br/jspui/handle/1/1313.
Анотація:
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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES)
Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG)
O comp?sito nFZV-CAG foi empregado para a ozoniza??o catal?tica heterog?nea da NMS em meio aquoso. O oz?nio foi gerado por uma central geradora de oz?nio IPABRAS, alimentada com ar. Foram avaliados diferentes processos catal?ticos como O3, CAG, O3-CAG, O3-nFZV- CAG, e a varia??o da concentra??o das nFZV para remo??o da NMS. Os resultados mostraram que a combina??o do O3-nFZV-CAG foi muito eficiente levando ? mineraliza??o de aproximadamente 70% da NMS em 120 min de rea??o. Tal efici?ncia pode estar atribu?da ao processo de eletr?lise, em que o Fe0 origina Fe2+ levando ? produ??o do radical hidroxila que ? altamente oxidante, levando a destrui??o do contaminante. As rea??es seguiram a cin?tica pseudo-primeira ordem para remo??o do f?rmaco. Ap?s realizada a coleta as amostras foram submetidas a an?lise qu?mica, empregando-se as t?cnicas de espectrofotometria de UV-Vis, cromatografia l?quida de alta efici?ncia (CLAE) e a determina??o da demanda qu?mica de oxig?nio (DQO) tamb?m foi realizada.
As nanopart?culas de FZV imobilizadas sobre a superf?cie do carv?o ativado (nFZV-CAG) foram sintetizadas e caracterizadas para remo??o do f?rmaco Nimesulida (NMS) em sistemas aquosos. Os estudos foram realizados em bateladas com agita??o de 250 rpm durante 120 minutos, onde foram avaliadas a efici?ncia, concentra??o (20, 25 e 30% do comp?sito) e diferentes dosagens (0,1 a 10g) de nFZV-CAG. Os resultados mostraram que a dosagem de 10 g de 20%nFZV-CAG removeu cerca de 80% da NMS 50 mg L-1 em apenas 30 minutos de rea??o, e atingindo 100% em 120 minutos. Foi observada ainda uma remo??o de 80% da DQO ao final da rea??o. As velocidades de rea??o aumentaram na medida em que foram aumentadas as dosagens do comp?sito, o que seria esperado. Por?m, com o aumento da concentra??o (%) de nFZV n?o houve aumento na velocidade das rea??es. As rea??es seguiram uma cin?tica de pseudo-primeira ordem em rela??o ? remo??o da NMS. Ap?s realizada a coleta, as amostras foram submetidas a an?lise qu?mica, empregando-se as t?cnicas de espectrofotometria de UV- VIS, cromatografia l?quida de alta efici?ncia (CLAE) e a determina??o da demanda qu?mica de oxig?nio (DQO) tamb?m foi realizada. Para caracteriza??o do comp?sito foram empregadas as t?cnicas Microscopia Eletr?nica de Varredura acoplada ? Espectrometria de Energia Dispersiva de Raios-X (MEV-EDS), que mostraram claramente a presen?a da nanopart?culas sobre a superf?cie do carv?o, e analise de superf?cie do nFZV-CAG e do CAG tamb?m foram realizadas.
Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016.
The FZV nanoparticles immobilized onto the surface of the activated charcoal (nFZV-CAG) were synthesized and characterized for the removal of the pharmaceutical Nimesulide (NMS) in aqueous systems. The studies were performed in batch mode with stirring speeds of 250 rpm during 120 minutes, so that it was possible to evaluate efficiency, concentration (20, 25 and 30% of the composite) and different dosages (0,1 to 10g) of nFZV-CAG. The results showed that the dosage of 10g of 20%nFZV-CAG removed approximately 80% of NMS 50 mg L-1 in just 30 minutes of reaction, and reaching 100% in 120 minutes. It was still observed a removal of 80% of the COD (Chemical Oxygen Demand) at the end of the reaction. The reaction rates increased with the dosage of the composite, which was expected. Though, increasing the concentration (%) of nFZV did not result in higher reaction rates. The reactions followed a pseudo-first order kinetics for the removal of NMS. After the samples were collected, they were submitted to chemical analysis, employing the techniques of UV-VIS spectroscopy, high performance liquid chromatography (HPLC) and chemical oxygen demand (COD). In order to characterize the composite, the following techniques were used: Scanning Electron Microscopy (SEM) coupled with Energy Dispersive x-Ray spectroscopy (EDS), which showed clearly the presence of nanoparticles onto the charcoal surface. Analysis of the surface of nFZV-CAG were also performed.
The composite nFZV-CAG was used for the catalytic ozonation of NMS in aqueous media. The ozone was generated by an ozone generator IPABRAS, fuelled with air. Different catalytic processes were evaluated such as O3, CAG, O3-CAG, O3-nFZV-CAG, and the variation of the nFZV concentration for the removal of NMS. The results showed that the combination of O3- nFZV-CAG was very efficient, leading to the mineralization of approximately 70% of NMS in 120 minutes of reaction. Such efficiency can be attributed to the electrolysis process, in which the Fe0 generates Fe2+ which generates hydroxyl radicals that are highly oxidant, leading to the destruction of the contaminant. The reactions followed the pseudo-first order kinetics for the removal of the pharmaceutical. After the samples were collected, they were submitted to chemical analysis such as, UV-VIS spectroscopy, high performance liquid chromatography (HPLC) and chemical oxygen demand (COD).
38
Martin, Benjamin David. "Removal and recovery of phosphorus from municipal wastewaters using a ferric nanoparticle adsorbent." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/5767.
Анотація:
Phosphorus is removed from wastewater streams to prevent the ecologically harmful effects of eutrophication in receiving natural systems. Current chemical and biological techniques for removing phosphorus from wastewater are not able to practicably achieve the new discharge limit expected under the Water Framework Directive of 0.1 mg phosphorus L- 1 . In addition, they do not represent an economically viable route for the recovery and reuse of the phosphorus they remove. Cont/d.
39
Ownby, Miles. "Phosphorus removal and recovery from wastewater via nano-enhanced adsorptive media." Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/40140.
Анотація:
L’augmentation rapide de la population mondiale et des pratiques industrielles et agricoles ont exacerbé l’épuisement des nutriments essentiels pour la croissance des plantes, phosphore en particulier, étant lui-même une ressource nonrenouvelable. Après des années d’exploitation agricoles et miniers écologiquement laxistes, la société se trouve coincée entre une pénurie croissante d'éléments nutritifs et la fréquence croissante de proliférations d'algues nuisibles (HAB) causées par la lixiviation de phosphore dans les systèmes aquatiques. Toutefois, ceci présente une opportunité de développer des nouvelles technologies permettant d'éliminer, de récupérer et de réutiliser le phosphore provenant de cours d'eau pollués. L'une de ces technologies est l'adsorption nano-renforcée. Cette étude a évalué le potentiel de désorber le phosphore d'une résine échangeuse d'ions hybridée avec des nanoparticules d'oxyde de fer pour quatre solutions de régénérations différentes en utilisant une approche de plan d’expériences. Des nouvelles solutions de régénération utilisant un mélange KOH / K2SO4 et une solution alcaline de NH4OH se sont révélées comparables à la solution "témoin" de KOH et de H2SO4. Parmi les 4 méthodes de régénération étudiées, la solution de NH4OH présente le potentiel le plus élevé car il s’agit d’un déchet valorisé. Son efficacité de désorption est comparable à celle de la solution de contrôle et elle n’a démontré aucune perte de la longévité de la résine après cinq cycles d’adsorption et de désorption. Sur la base des données du plan d’expériences, une série de modèles de régression a été développée pour permettre de mieux comprendre la concentration de phosphore attendue d'un processus de régénération, en tenant compte de la chimie de régénération, du volume de traitement, de la vitesse de rinçage et de la résistance de la solution alcaline. Les solutions de post-désorption de régénération riches en nutriments semblent prometteuses pour une utilisation ultérieure. Les travaux futurs devraient inclure le développement de modèles de procédé afin de mieux comprendre les mécanismes de cette désorption. Dans l’ensemble, la technologie d’adsorption nano-améliorée offre une solution rentable et durable au problème du phosphore dans les applications de traitement des eaux usées à travers le monde.Rapid increases in the world’s population and to-date industrial and agricultural practices have exacerbated the depletion of essential nutrients in today’s society. After years of environmentally lax agricultural and mining processes, society finds itself trapped between increasing nutrient shortage and the increased frequency of harmful algal blooms (HABs) caused by phosphorus leaching into water systems. New technologies that allow for removal and subsequent recovery and reuse of phosphorus from polluted streams is imperative. One such technology is nanoenhanced adsorption, which may allow to produce a valuable nutrient-rich solution upon desorption of the saturated media. This study evaluated the potential of four regeneration chemistries to desorb phosphorus from a commercially available ion exchange resin hybridized with iron-oxide nanoparticles using a Design of Experiments (DoE) approach. Novel regeneration solutions using a KOH/K2SO4 blend and a recovered NH4OH alkaline solution proved to be comparable to the "control" solution of KOH and H2SO4. Among the four regeneration methods studied, using the NH4OH solution shows the highest potential because: i) it is a valorized waste stream, ii) it showed a desorption efficiency comparable to the control solution, and iii) it did not demonstrate any dampening of the resin longevity after five adsorption and desorption cycles. Based on the DoE data, a series of regression models was developed to generate understanding with regard to expected phosphorus concentration from a regeneration process considering the regeneration chemistry, the treatment volume, the rinse speed, and the strength of the alkaline solution. Nutrient-rich regeneration solutions post-desorption show promising for subsequent use as hydroponic fertilizers or precursors for the P fertilizer industry. Future work should include the development of mechanistic process models to gain an even better understanding of the mechanics behind the desorption. Overall, the nano-enhanced adsorptive technology proposes a cost-effective and sustainable solution to the phosphorus problem in wastewater treatment applications across the globe.
40
Nawotka, Alexis. "Evaluation of Small Unilamellar Vesicles as a Removal Method of Benzo[a]pyrene from Humic Substances in Soils." Master's thesis, Temple University Libraries, 2019. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/592708.
Анотація:
GeologyM.S.
Polycyclic aromatic hydrocarbons (PAHs) are highly hydrophobic and lipophilic and are readily retained by soil surfaces and organic matter. Hence, several techniques have been developed in an effort to economically and effectively remove them from soil solids. Their strong affinity to soil organic matter limits their biodegradation processes by microorganisms, making them persistent in the soil environment. Recently, the use of “small unilamellar vesicles” (SUVs), nano-scale lipid aggregates, has been proposed as a means to enhance these microbial degradations, by effectively solubilizing lipophilic PAHs from the soil solids. In this thesis, laboratory-scale batch experiments were performed to examine this potential by measuring the uptake of benzo[a]pyrene (BaP), a model PAH compound, by SUVs from a simulated soil organic matter. This environmental surface was created by coating silica (SiO2) nanospheres with a layer of poly-L-lysine, followed by humic acid, and characterized by dynamic light scattering for particle size and zeta potential values. Then, these humic acid-bound SiO2 particles were saturated with BaP and then equilibrated with SUVs. The uptake of BaP by SUVs was measured through fluorescence spectroscopy, and the average amount of BaP concentrated in the 1 mg/L humic acid-bound SiO2 particles was found to be 1.77 µg/L. After one week of equilibration with SUVs, 94.4% and 83.6% of the added BaP was solubilized by SUVs (in solutions containing 50 mg/L and 100 mg/L of vesicles, respectively), indicating an excellent ability to extract BaP from the soil organic particles. SUVs can therefore be an effective vehicle to enhance the biodegradability of PAHs in soils, with potential as an environmentally sustainable and affordable method.
Temple University--Theses
41
Sarina, Sarina. "New catalysts for organic synthesis driven by light and efficient sorbents for removal of radioactive ions from water." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/63963/2/Sarina_Sarina_Thesis.pdf.
Анотація:
The body of the thesis contained two separate elements which made an original contribution to fundamental understanding in the areas of photocatalysis, chemical synthesis and water treatment. Research on chemical reactions catalyzed by noble metal nanoparticles (such as gold) or surface complex grafted metal oxides which can be driven by sunlight at ambient temperature and the second element on radioactive cesium (137Cs+) cations and iodine (125I-) anions recovery by the unique structural features of titanate nanostructures for firmly capture and safe storage; the works has been all published in journals that are rated at the top of their respective fields.
42
Zhang, Ming. "Elimination de nanoparticules par des procédés de flottation." Thesis, Toulouse, INSA, 2015. http://www.theses.fr/2015ISAT0012/document.
Анотація:
La séparation de nanoparticules (NPs) contenues dans des milieux aqueux est un sérieux challenge pour le traitement des eaux à cause de la grande stabilité et de la nature colloïdale de ces particules. Ce travail concerne le développement de procédés efficaces de flottation pour la séparation de nanoparticules. La première partie du travail est conduite pour obtenir une connaissance plus étroite de la nature et du comportement colloïdal des nanoparticules en suspension. Des tests de modifications de leur surface et des expériences d’adsorption-agrégation sont ensuite menés pour comprendre les mécanismes d’interactions entre les NPs et des réactifs d’aide à la flottation. Deux type des techniques de flottation (la flottation à air dissout (DAF) et la flottation par des aphrons colloïdaux (CGAs)) sont utilisés : le premier type a ici pour objectif de séparer les nanoparticules par des bulles d’air avec l’aide d’acides humiques (HA), alors que le second utilise des microbulles dont la surface est fonctionnalisée par des tensioactifs (CGAs), dans l’objectif d’accroître l’efficacité de séparation. Les résultats montrent que, par mélange avec une solution basique de HA (pH 12.9), la charge de surface de nanoparticules de TiO2 (TNPs) est d’abord neutralisée par des ions OH- et ensuite écrantée par les polyanions de HA. Quand le pH des suspensions TNPs-HA est en dessous de 3 par ajout de solution mère de HA de pH 4.9-9.0, l’attraction électrostatique entre les TNPs et les anions est insuffisante, mais on observe quand même l’agrégation entre TNPs et la part colloïdale de l’HA. Par des essais de DAF en continu, le pH optimal de la solution mère de HA (pH≦ 9) et la concentration optimale en HA (11.1 mg/L COD) permettent d’éliminer plus de 95% des nanoparticules. La concentration résiduelle de HA reste à un très bas niveau même quand l’acide humique est surdosé. Quand le pH des suspensions TNPs-HA est très acide, la plupart des molécules d’acides humiques ne sont pas solubles et ne sont pas chargées. Elles peuvent s’agréger entre-elles et former un précipité colloïdal hydrophobe pour minimiser leur contact avec le milieu aqueux. En ce qui concerne les CGAs, leur caractérisation montre que la vitesse d’agitation est un paramètre crucial pour créer des aphrons de l’ordre de la dizaine de micromètres. Les CGAs peuvent être chargés négativement ou positivement en utilisant des tensioactifs adaptés. Différentes nanoparticules de SiO2 (SNPs) peuvent être efficacement (près de 100%) séparées de suspensions aqueuses par le procédé continu de flottation par CGAs. La comparaison entre flottation par CGAs et DAF montre l’avantage du premier procédé plus efficace avec une moindre quantité de surfactantThe removal of nanoparticles (NPs) from waters is a serious challenge in the water treatment field owing to the high stability and colloidal nature of particles. This study is devoted to develop effective flotation processes for NP separation. The investigation is firstly conducted to get a good knowledge of features and colloidal behaviors of NPs in suspension. Surface modification tests and adsorption-aggregation experiments are then carried out to understand the interaction mechanisms between NPs and flotation assisting reagents. Two types of flotation (dissolved air flotation (DAF) and colloidal gas aphrons (CGAs) involved flotation) were specially focused on: the former aims at using air bubbles to remove NP aggregates with the assistance of humic acid (HA), while the later employs the surface functionalized microbubbles, CGAs, to enhance the interaction of NP-bubble for the sake of high treating efficiency. Results show that, on mixing with the highly basic HA solution (pH12.9), the surface charge of TNPs is primarily neutralized by and then screened by polyanions of HA. When the pH of TNP-HA suspension is lower than 3 by adding HA stock solutions at pH4.0~9.0, the electrostatic attraction between TNPs and anions becomes insufficient but the aggregation of TNPs-colloidal HA occurs. In continuous DAF trials, the appropriate pH of HA stock solution (pH ≦ 9) and optimum HA concentration (11.1 mg/L DOC) for high TNP removals (> 95 %) are determined. The residual HA concentration remained in a low level even when HA is overdosed. When the pH of the TNP-HA suspension is highly acidic, most HA molecules are not really soluble and uncharged, and they may aggregate themselves and form hydrophobic colloidal precipitates to minimize the contact with the aqueous environment. As for the study of CGAs, the characterization results denote that introducing air flow during the CGA generation process can slow down the liquid drainage speed and may facilitate the particle separation performance; the stirring speed is a crucial parameter to create micron scale bubbles, and CGAs can be positively or negatively surface charged by using different surfactants. Different SiO2 NP (SNPs) can be efficiently separated from aqueous suspensions by the continuous CGA generation-flotation process with the highest SNP removal close to 100 %. The comparison tests between CGA-flotation and DAF denote that the former take the greater advantage because of its better treating effect and less surfactant demand
43
Abutin, Megan P. "Effects of Using Clay Nanoparticles as a Soil Amendment to Remove Nitrate from Stormwater." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1908.
Анотація:
Development of urban areas continues to increase, disrupting the natural ecosystem and the pathways for water to drain into downstream water bodies. As the amount of impervious area increases, pollutants can accumulate on the surface and enter the water cycle by stormwater. In most cities, the stormwater flows into a storm drain that is discharged into a water body. Low Impact Development technology has been developed to treat stormwater prior to discharge downstream. A bioretention cell is used to treat stormwater pollutants such as nitrate, phosphorus, total suspended solids, and metals. Past research has indicated that the removal efficiency of nitrate by bioretention cells greatly varies from a 75% reduction in nitrate concentration to the addition of nitrate in the effluent from leaching of the bioretention cell. It is important to remove nitrate from water because it can cause negative environmental and human effects. Excess nitrate in the environment can lead to eutrophication, resulting in the death of fish. If ingested by infants, nitrate can cause “blue baby syndrome” leading to death. One area of study that focuses on the removal of nitrate from stormwater is maximizing the efficiency of the designed soil media. The addition of a clay amendment could lead to higher removal efficiencies. The use of clay nanoparticles, or nanoclays, can maximize the amount of surface area available for adsorbance potentially increasing the amount of nitrate removed from water. The goal of this study was to identify a nanoclay with high adsorbance by testing its nitrate removal efficiency and then determining if it would be feasible to add to a bioretention cell by calculating the hydraulic conductivity to compare to industry design values. This study analyzed a montmorillonite clay, a bentonite nanoclay, and a pre-modified trimethyl stearyl ammonium nanoclay as a 1% w/w added amendment to a Nevada sand to determine the number of pore volumes required until the system reached breakthrough. The pre-modified nanoclay required the highest amount of water, 19 pore volumes, until breakthrough was reached. The fraction of nanoclay was increased to 2% w/w and breakthrough was not seen in the volume of water that was filtered through the system. The hydraulic conductivity for this nanoclay/sand mixture was 14 in/hr, greater than most minimum design values. Since the results so far indicated that this mixture would efficiently remove nitrate and still meet the minimum hydraulic conductivity, a synthetic stormwater solution was filtered through the column to test the nitrate removal when it is competing with other pollutant ions. This resulted in a projected breakthrough of 27 pore volumes and a 9 in/hr associated hydraulic conductivity. Future research can be completed to assess the best methodology to homogeneously mix the nanoclay particles with the sand to prevent leaching of the nanoclays. The next step in optimizing a bioretention cell for water quality treatment would be to focus research on how plants affect the system. If plants are able to remove nitrate from the system entirely, the lifetime of the bioretention cell could increase.
44
He, Wenyan. "Coupling of an electrochemical process and a biological treatment for specific pollutant removal-Electrode surface functionalization." Rennes, Ecole nationale supérieure de chimie, 2016. http://www.theses.fr/2016ENCR0035.
Анотація:
La réduction électrocatalytique couplée à un procédé biologique est une solution prometteuse pour la dégradation des composés chlorés. L’attaque sélective de la liaison carbone-chlore en milieu aqueux est mise en oeuvre pour réduire la toxicité et augmenter la biodégradabilité de composés chlorés ; la minéralisation de la solution peut ensuite être achevée par voie biologique. La déchloration a été réalisée en présence de complexes de métaux de transition et de nanoparticules d’argent, en raison de leur forte activité catalytique, ce qui a conduit à une dégradation totale des composés organo-halogénés ciblés avec une bonne sélectivité. La modification de feutres de graphite à l’aide des complexes Ni(tmc)Br2 ou [Co(bpy(CH2OH)2)2]2+ et leur mise en oeuvre dans la réaction de déchloration du 1,3-dichloropropane et de l’alachlore ont montré une plus grande stabilité du catalyseur et de meilleurs rendements faradiques comparés aux résultats obtenus en catalyse homogène. Le deschloroalachlore est le principal sous-produit de l’électroréduction de l’alachlore, ce qui souligne la forte sélectivité du complexe de cobalt. La biodégradabilité de la solution a été améliorée, puisqu’une valeur de 0. 31±0. 04 a été obtenue pour de la mousse de nickel modifiée par ajout de nanoparticules d’argent (dans de la soude 0. 05 M), avec la formation de produits organiques non chlorés, autres que le deschloroalachlore. Par ailleurs, du feutre de graphite métallisé par du nickel et modifié par ajout de nanoparticules d’argent devrait permettre d’améliorer les performances catalytiques de la cathode en augmentant la surface du supportThe electrocatalytic reduction coupled to a biological process is a promising alternative for the degradation of chlorinated compounds. The selective cleavage of the carbon-chlorine bond in aqueous media was implemented for detoxification and to improve the biodegradability of chlorinated compounds. The mineralization of the electrolyzed solution can then be achieved by a biological treatment. The dechlorination was studied with the aid of transition metal complexes and Ag nanoparticles because of their high catalytic activity, leading to a total degradation of the organohalogenated studied compounds with good selectivity. The modification of graphite felt with Ni(tmc)Br2 or [Co(bpy(CH2OH)2)2]2+ complex highlighted the catalyst stability and current efficiency for dechlorination of 1,3-dichloropropane and alachlor , respectively, compared to the homogeneous process. Deschloroalachlor, was the main by-product of the electroreduction of alachlor, indicating the high selectivity of the Co complex system. The biodegradability of the solution was improved to 0. 31±0. 04 using Ag nanoparticles modified Ni foam in 0. 05 M NaOH solution with production of other dechlorinated by-products apart from deschloroalachlor, highlighting the interest of this new material. The new Ag nanoparticles modified graphite felt with Ni layer aimed at improving the catalytic performance of cathode by increasing the surface area of the support
45
Shipley, Heather J. "Magnetite nanoparticles for removal of arsenic from drinking water." Thesis, 2007. http://hdl.handle.net/1911/20649.
Анотація:
Arsenic has become a major contaminant of concern due to the increased knowledge of its toxicological and carcinogenic effects on human health, causing the maximum contaminant level (MCL) to be lowered from 50mug/L to 10mug/L in the United States. Lowering the MCL requires improving current methods or developing new ones to remove arsenic from the drinking water. Currently, there are many methods to remove arsenic, such as coagulation iron salts, ion exchange, and membranes. These methods can be expensive, have poor removal efficiency, and produce a large amount of waste. In this research, magnetite nanoparticles are evaluated as arsenic sorbents due to there magnetic properties for removal, minimal production of waste, and high surface area. Also, in this work, the kinetics of adsorption was examined along with the competitive adsorption of other ions (chloride, phosphate, sulfate, silica, and bicarbonate) in solution. Equilibrium was reached in about two hours for arsenate and arsenite; however, approximately 90% of the arsenate and arsenite was adsorbed within thirty minutes with 0.5g/L Fe3O4. The arsenate and arsenite equilibrium concentrations are similar which demonstrates the affinity of magnetite nanoparticles for both arsenite and arsenate. This work presents a model which predicts the amount of arsenic adsorbed by magnetite nanoparticles in the presence of several ions using a modified rate equation. To test the viability this arsenic removal method, it was tested on spiked arsenic tap water and arsenic contaminated groundwater from Brownsville, TX. In each case, the treatment goal of less than 10mug/L was reached with minimum residual iron in the water. Therefore, these results suggest that using magnetite nanoparticles is a feasible process to remove arsenic from the drinking water. This process could be applied as a household treatment system for developing and developed countries.
46
Sousa, Vânia Sofia Serrão de. "Development of drinking water treatment processes for nanoparticles removal." Doctoral thesis, 2020. http://hdl.handle.net/10400.1/15245.
Анотація:
The ability of drinking water treatments (DWT) to remove ENPs from water is crucial to
ensure the safety of public water supply. This thesis assessed the removal of three comercial metal-based nanoparticles, titanium dioxide (TiO2), silver (Ag) and copper oxide (CuO) in DWT, exploring and comparing the potential of conventional and advanced processes. To understand the removal mechanisms, individual ENPs and mixtures of the three ENPs, dispersed in synthesised and natural surface waters were used. Conventional coagulation/ flocculation/ sedimentation (C/F/S) process alone and enhanced with powdered activated carbon (PAC) were studied, and the advanced membrane filtration processes, ultrafiltration (UF) and nanofiltration (NF), were integrated with conventional C/F/S (hybrid water treatment) or used alone (NF). These technologies were evaluated under typical DWT operational conditions. Overall, results show that optimised treatments are able to remove ENPs, without hampering other DWT target compounds. Residual turbidity, dissolved organic carbon, specific UV absorbance and aluminium were below the guidelines and similar to those found in actual DWTP. C/F/S removed 93% and 98% of the tested ENPs, depending on water characteristics. C/F/S+PAC and C/F/F→UF treatments improved the removal of single and multiple ENPs in approximately 10% compared with C/F/S alone, with Ti and Cu undetected in the C/F/S→UF treated water. However, due to AgNPs dissolution, residual Ag concentrations were present in the C/F/S→UF treated water. Using NF, the dissolved Ag was eliminated from treated water to undetectable values (depending on water characteristics). The main mechanisms responsible for the removal were charge neutralisation (C/F/S), size exclusion (UF and NF), adsorption and complexation with salts and adsorption on NOM (PAC and NF). This study contributes to the advancement of knowledge on the removal of emerging contaminants from drinking water, demonstrating that the processes optimisation for the ENPs removal is a key factor to ensure safe water, reducing the potential hazards associated to the ingestion of these contaminants and meeting the drinking water quality guidelines.A capacidade de controlar e manipular a forma e o tamanho de estruturas à escala nanométrica veio revolucionar diversas áreas industriais, possibilitando a criação de produtos adaptáveis, mais eficientes e de baixo custo através da integração de nanomateriais manufaturados, especialmente nanopartículas (NPs). Contudo, o crescimento exponencial de produtos do quotidiano contendo NPs leva à introdução destas nanoestruturas no meio aquático, originando potenciais riscos toxicológicos tanto para o ambiente como para a saúde humana. As características intrínsecas das NPs, tais como tamanho reduzido, forma variada, área superficial elevada, assim como as suas capacidades de agregação e dissolução, proporcionam uma maior reatividade, podendo ampliar o seu efeito tóxico e tornando-as responsáveis por efeitos nocivos nos organismos vivos. A introdução de NPs manufaturadas em águas superficiais utilizadas para a produção de água para consumo apresenta um elevado risco para a saúde humana, uma vez que pode levar à exposição direta às NPs através da ingestão de água contaminada. A ingestão de NPs pode causar efeitos adversos à saúde humana, tais como problemas renais, inflamações gastrointestinais, implicações ao nível do sistema neurológico e doenças cancerígenas. Embora ainda existam algumas dúvidas relacionadas com a toxicidade destas nanoestruturas, algumas NPs já foram identificadas como tóxicas para a saúde humana, nomeadamente as de origem metálica, onde se incluem as NPs de TiO2, Ag e CuO. Atualmente, já foram detetadas NPs em águas superficiais, águas para consumo humano e em água da torneira com concentrações entre os ng/L e os μg/L. Embora o tratamento de água seja uma das principais estratégias para evitar a exposição humana às NPs através da ingestão, os poucos estudos existentes descrevem os tratamentos convencionais como sendo ineficientes na sua remoção. Estes estudos, para além de mostrarem uma elevada variabilidade nas eficiências de remoção, foram maioritariamente realizados usando elevadas concentrações de NPs dispersas em água ultrapura, da torneira ou soluções sintéticas, sem considerarem a complexidade das águas superficiais naturais. Assim sendo, este trabalho pretendeu estudar a capacidade dos tratamentos de água convencionais e avançados para remover nanopartículas de águas superficiais. Para tal, a remoção de NPs de origem metálica foi explorada e avaliada usando diversas estratégias de tratamento, de modo a garantir uma eficiente remoção de NPs e de iões provenientes da sua dissolução. Os tratamentos propostos tiveram também por base a minimização do impacte da requalificação das estações de tratamento de águas para consumo humano recuperando os processos mais utilizados na produção de água potável. Para os ensaios foram escolhidas nanopartículas manufaturadas disponíveis comercialmente, TiO2, Ag e CuO, com base na sua elevada produção e aplicação em produtos do quotidiano. De modo a compreender os mecanismos de remoção, as NPs foram usadas individualmente e em conjunto dispersas em águas sintéticas (águas modelo) e águas naturais provenientes de barragens (Alentejo e Algarve) atualmente utilizadas para a produção de água para consumo humano. Em todas as opções de tratamento estudadas, os processos foram sempre otimizados tendo em vista a maximização da remoção das NPs, aplicando condições operacionais típicas em contexto real de tratamento de água. O tipo e doses de coagulante e carvão ativado testados são também usados em contexto real. O tratamento convencional coagulação/floculação/sedimentação (C/F/S) demonstrou ter capacidade para remover NPs, tanto em águas sintéticas como naturais, utilizando um coagulante polimérico de alumínio. Este processo apresentou eficiências elevadas (ca. 95%) tanto na remoção das NPs individualmente, como na sua remoção simultânea (variando entre 93% e 99% dependendo da NP e das características da água. Contudo, foi observado que para alcançar remoções semelhante de NPs de TiO2, as águas hidrofóbicas necessitam de uma dose de coagulante mais elevada do que as hidrofílicas. Ao contrário das características das águas, a presença de diferentes NPs em conjunto não afetou a dose de coagulante necessária. Determinou-se que o mecanismo de remoção de NPs mais provável foi a neutralização de cargas. No final do processo, as concentrações residuais de NPs nas águas tratadas foram, 6.5±2.1 e 2.5±0.7 μg Ti/L, 15.0±1.4 e 6.0±1.4 μg Ag/L, e 18.8±8.8 e 0.5±0.1 μg Cu/L, para a água natural com menor turvação e matéria orgânica natural (NOM) e para a água natural com maior turvação e NOM, respetivamente. De modo a diminuir as concentrações residuais de NPs na água tratada, o processo convencional C/F/S foi combinado com a adsorção por carvão ativado em pó (C/F/S+PAC) e integrado com o tratamento avançado ultrafiltração (UF) num processo de tratamento híbrido (C/F/S→UF). O processo C/F/S+PAC foi mais eficiente na remoção das NPs de TiO2 (>99.9%), com o Ti a apresentar concentrações inferiores ao limite de deteção na água tratada. Para o mesmo tratamento as remoções de Ag e Cu foram superiores a 99.2%. Com a aplicação do tratamento híbrido (C/F/S→UF), não foram detetadas concentrações residuais nem de Ti nem de Cu na água filtrada. Contudo, foram detetadas concentrações entre 5.0 e 7.0 μg/L para a Ag. Este resultado foi associado à dissolução das AgNPs, uma vez que, tendo em conta o menor tamanho do poro da membrana comparado com o tamanho individual das NPs e dos agregados formados, a parte nanoparticulada foi removida. Com o intuito de remover tanto AgNPs, como os iões provenientes da dissolução foi utilizado o tratamento avançado de nanofiltração (NF). Com este tratamento os agregados e as nanopartículas individuais foram completamente removidas por exclusão de tamanho, tendo a remoção de Ag dissolvida chegado aos 99.9%, dependendo do conteúdo de sais e matéria orgânica natural das águas testadas. Os resultados obtidos permitem concluir que é possível remover de forma eficaz NPs durante o tratamento de água para consumo humano, utilizando uma combinação/sequência de tratamentos convencionais e avançados, sem prejudicar a qualidade da água final. Tal foi demonstrado pela comparação dos valores residuais de turvação, carbono orgânico dissolvido, SUVA (absorvência específica) e alumínio com os valores paramétricos nacionais e internacionais para a água para consumo humano. Uma linha de tratamento integrando C/F/S+PAC, seguido de UF ou até mesmo NF, apresenta-se como uma solução segura para eliminar a ameaça de ingestão de NPs através de água potável.
PhD Grant (SFRH/BD/100402/2014) from the Portuguese Foundation of Science and Technology, trough the European Social Found from European Union. CENSE – Center for Environmental and Sustainability Research which financed by national funds FCT/MCTES (UID/AMB/04085/2019).
47
Wei, Chao-Yuan, and 韋朝源. "The synthesis of zero valent copper nanoparticles for hexabromocyclododecane removal." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/zhsu8x.
Анотація:
碩士國立臺灣大學
農業化學研究所
105
Because of flooding and microbial metabolism, humic acid in some natural reduction environments could be reduced and then interact with metal ions; moreover, the copper ion is easily to be reduced. To understand whether a reduced condition can facilitate the formation of zero valent Cu NPs and then interact with persistent organic pollutant (POP), HBCD, one of POP, is chosen as a target compound. First, Cu NPs were synthesized by sodium borohydride. The removal of HBCD by Cu NPs was increased with the Cu NPs dosage increased but with the initial HBCD concentration decreased. The highest rate constant presented in 3.5 g/L Cu NPs, moreover the mass-normalized rate constant was 14.4 min-1g-1. The removal of HBCD was also increased with the temperature increased. The estimated activation energy was about 32.21 kJ/mol, which is considered as surface controlled reaction. The removal of HBCD was decreased with the initial pH increased. However, with pH increased the passivation of Cu NPs such as copper (hydro)oxide was found and then contributed to the increase of HBCD adsorption efficiency. On the other hand, the pHzpc of Cu NPs is 8.1, the Cu NPs would aggregate with the increased pH and then reduce the rate constant. To understand the transformation of complexes of reduced humic acid and cupric ion, humic acid was chemically reduced by sodium borohydride, and cupric ion was well-mixed with the reduced humic acid (RHA) under different Cu(II) ion dosages and incubation period. The copper species of RHA-Cu were organic acid-copper complexes after the reacting time of 12 hours. Metallic copper was observed for the reacting time of 48 hours in the condition of 0.9 g/L RHA with 175 mmol/kg Cu(II) which were analyzed by X-ray adsorption near edge structure. The spatial distribution of zero valent copper in the humic acid were investigated by scanning photoemission microscopy. There were two peaks at 1384 and 1598 cm-1 owning to the carboxylate vibrations, indicating that the HA complexes with Cu(II) via chemical bonding which were investigated by Fourier transform infrared spectroscopy. The particle size of metallic copper of RHA-Cu was around 50 nm was analyzed by single particle-inductively coupled plasma-mass spectrometry. The removal efficiency of HBCD by RHA-Cu was 34.5% after 24 hours and bromide ions were detected, indicating a reduction and debromination reaction of HBCD. Our results demonstrate the metallic copper can be synthesized by humic substances in a redox condition, which could provide a potential for HBCD removal through this abiotic chemical process.
48
Shih, Cheng-Jhih, and 石承治. "Heavy Metal Removal from Wastewater Using Zero-Valent Iron Nanoparticles." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/08799452939922399615.
Анотація:
碩士國立高雄第一科技大學
環境與安全衛生工程所
95
The purpose of this study was aimed to investigate the reaction behavior of heavy metals (Cu、Zn、Pb、Ni、Cr) with zero-valent iron (ZVI) nanoparticles in the wastewater. The influence factors, such as initial pH, dosage of nanoscale ZVI and initial concentration of heavy metal, on the removal efficiency of heavy metals by ZVI in the wastewater were examined by the batch experiments in this study.Furthermore, the analysis of X-ray diffraction (XRD) was carried out to observe the products on the ZVI surface after the treatment of heavy metals from the wastewater. The results showed that the removal of heavy metals was affected by initial pH. The rate and efficiency of metal removal increased with decreasing initial pH. Higher than 90 % of the heavy metals (Cu、Zn、Pb、Cr) was removed when the initial pH was controlled at 2. The removal efficiency of heavy metal were in the decreasing order: Cu = Cr > Zn = Pb > Ni. In addition, the rate and efficiency of metal removal increased as the dosage of nanoscale ZVI increased. The removal efficiency of heavy metal was higher than 80% when 2.0 g/L of ZVI was added in the wastewater. On the other hand, the slow rate and low efficiency of metal removal from the wastewater treated by nanoscale ZVI was found in the wastewater with high concentration of heavy metal. Generally, the removal kinetic of heavy metals from the wastewater by nanoscale ZVI was well described by the pseudo-first order reaction. The XRD analysis revealed that iron corrosion products including r-FeOOH、 Fe6(OH)12SO4．nH2O and/or Fe(II)Fe(III)3(OH)12Cl3．H2O were formed at the surface of nanoscale ZVI particles after the treatment of heavy metals from the wastewater.
49
Desai, Ishan. "Mercury Removal from Aqueous Systems Using Commercial and Laboratory Prepared Metal Oxide Nanoparticles." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-08-6973.
Анотація:
Five commercial metal oxide nanoparticles (CuO, SiO2, Fe2O3, TiO2 and Al2O3) have been individually screened for mercury removal in a batch reactor under bicarbonate buffered and non-buffered aqueous solutions (DI water). Copper oxide was then selected for surface modification to enhance mercury removal. The surfaces of both laboratory prepared and commercially available copper oxide nanoparticles were treated with 1-octanethiol to produce
copper sulfide and/or copper alkanethiol nanoparticles. The resulting particles were characterized using
X-Ray Fluorescence(XRF),
X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The novel nanoparticles demonstrated very high mercury removal (> 99%) from both the
buffered and non-buffered aqueous solutions.
50
Yean, Su Jin. "Arsenic removal using iron oxides: Application of magnetite nanoparticles and iron salts." Thesis, 2008. http://hdl.handle.net/1911/22252.
Анотація:
Elevated levels of arsenic in groundwater have generated great attention worldwide because of its wide occurrences throughout the world and toxicity at low concentration. This work introduces a possible application at household levels to provide arsenic-safe water using nanoscale iron oxide (i.e., magnetite nanoparticles) and iron salts (i.e., ferric nitrate and ferric chloride) as adsorbents and coagulants, respectively. Recent publications illustrate that more than 70 million people are chronically exposed to arsenic-contaminated groundwater and suffer from skin lesions and cancers worldwide. A number of technologies (for example, ion exchange and membrane methods) are currently available to remove arsenic; however, each technique has drawbacks to be applicable in the developing countries. Therefore, it is crucial to develop a technology to treat arsenic-contaminated groundwater. Our results show an immediate reduction of arsenic concentration in solution to meet the maximum contaminant level of arsenic (10 microg L-1) in drinking water. Also, iron concentrations in solution are below the World Health Organization guideline value of 300 microg L-1. Contrary to previous results reported by other researchers, arsenic(III), known as more problematic in natural water, is also removed as effectively as arsenic(V) by using our method. When citrate, one of most common organic ligands in environments, is initially added to arsenic-containing solutions, the formation of iron oxides from iron salts is completely inhibited and resulting arsenic concentration remains the same as the initial arsenic concentration, indicating that arsenic removal does not occur. However, other common carboxylic acids such as tartarate, succinate, malate, formate, and tricarballylate, have a negligible impact on preventing the formation of iron hydroxides and resulting arsenic removal from solution. This work shows the efficient method to reduce high arsenic concentrations in groundwaters and better understanding of arsenic removal mechanisms using iron salts and iron oxides.