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Santos, Pedro Deyrieux Centeno Ogando. "Heavy metals removal in dual media filters." Master's thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/8251.
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Dissertação para obtenção do Grau de Mestre em
Engenharia do Ambiente – Perfil de Engenharia SanitáriaThe purpose of this study was to investigate physicochemical mechanisms for the removal of heavy metals from the effluent of Harnaschpolder’s WWTP Pilot Installation in the South of Netherlands. This effluent is partially submitted to tertiary treatment in a water reuse pilot which aims the production of water for two different end‑uses: crop irrigation in greenhouses and surface‑type water. Tertiary filters were mounted and started up at the reuse pilot and specific concentrations of heavy metals were dosed in the filters. Removal efficiencies were then calculated after the end of the experiments. As a parallel research project, the removal of HM was also carried out by inoculating selected bacteria (biosorption). Solubility curves were calculated for the dosed heavy metals (Cd, Cu, Ni, Zn) using PHREEQc programme, to predict if heavy metal precipitation occurred in the filters (using the same experimental data: temperature, pH , alkalinity, etc.). Results show that physicochemical precipitation was not the primary removal mechanism for heavy metals. The results suggest that other mechanisms such as adsorption and/or chelation may be involved in the removal of these species.
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Li, Litong. "Heavy metals removal from wastewater by peat absorption /." Connect to online version, 1996. http://hdl.handle.net/1989/3561.
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Muhammad, Nur. "Removal of heavy metals by slow sand filtration." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/6981.
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Slow sand filters (SSFs) are probably the most effective, simplest and least expensive water treatment process. Micro-organisms and other particulate materials are effectively removed by SSFs. Considerable development has been done on SSFs with respect to particle removal, but only a few works have been reported in the context of the removal of heavy metals which are a severely toxic pollutant of surface waters. No extensive laboratory or pilot studies have been carried out to determine the performance or the mechanisms of removal of heavy metals by SSFs. This research is concerned with an experimental investigation of the removal of heavy metals from surface water by SSFs. Four laboratory scale SSFs were built and run according to standard design criteria. Removal of four common heavy metals [copper (Cu), chromium (Cr), lead (Pb) and cadmium (Cd)] were monitored. The filters were fed synthetic water made from tap water mixed with settled sewage, and each filter was dosed with one of the heavy metal salts. The concentrations of Cu, Cr, Pb and Cd in the influent were selected as 10 mg/l, 100 μg/l, 60 μg/l, and 100 μg/l respectively considering their relative toxicity and WHO guidelines in drinking water. Settled sewage was added to vary the total organic carbon (TOC) of the feed water. The reduction of heavy metal concentrations were monitored at various TOCs, filtration rates and filter bed depths. The results showed that SSFs succeeded in removing heavy metals from water. The removals of Cu, Cr, Pb and Cd at the conventional flow rate and filter depth are 99.6,97.2,100 and 96.6 % respectively. The results also showed that an increase in TOC in the feed water improved metal removal while increases of flow rates caused a decrease of the removal of metals. The removal of heavy metals also decreased with a reduction in sand bed depth. The optimisation of design parameters for SSFs for the removal of heavy metals depends on the individual heavy metal and on the TOC content of the feed water. Model equations were developed for, and linear correlation was observed between each of the three control parameters and the removal of the selected metal. The removal of heavy metal by SSFs was achieved through the combination of a number of mechanisms. Settlement, adsorption to both sand and organic matter and microbial
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Strelko, Vladimir. "Selective removal of heavy metals using novel active carbons." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/7182.
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Porous carbonaceous adsorbent materials possessing weakly acidic surface functional groups have been evaluated for the selective removal of heavy metals from aqueous solutions. Active carbons derived from both agricultural products (KAU carbons) and polymeric resin (CKC carbon) have been oxidised by hot air or nitric acid to produce samples with different degrees of surface oxidation. A novel phosphorus-containing carbonaceous sorbent (PGP-P) has been prepared by pyrolysis of phosphorylated phenol-formaldehyde resin. Surface modifications have been carried out to introduce various acidic functional groups capable of selective heavy metal binding. The properties of these sorbents have been compared to those of commercially available polymeric carboxylic resin C 104 (Purolite) and oxidised Filtrasorb 400 (Chemviron). Investigation into the physical structure of the adsorbents using microscopy and nitrogen sorption at liquid nitrogen temperatures showed that the porous structure is adversely affected by carbon oxidation. The surface area and pore volume decrease as the degree of surface oxidation increases. The low surface area and pore volume of PGP-P was attributed to the presence of phosphorus-containing functional groups which protect the surface from excessive burn-off. The surface functionality of the sorbcnts was determined by FT-IR, NMR and X-ray photoelectron spectroscopy. Relatively high concentrations of different weakly acidic functional groups were detected on the surface of the materials studied. The ion-exchange properties of the sorbents were assessed by acid-base titration techniques and electrophoretic mobility measurements. Oxidation of carbons with hot air resulted in a greater proportion of relatively weaker type surface functionality (i.e. phenolic) whereas nitric acid modification produced a higher concentration of relatively stronger carboxylic groups. Electrophoretic mobility measurements suggested that the carbon surface is negatively charged within the range of pH values studied. pH titration results demonstrated relatively greater surface acidity of active carbons compared to carboxylic resin. Active carbons were successfully applied for the selective removal of radionuclides. The materials showed excellent decontamination factors for a-, b- and y emitters. This was attributed to the presence of mineral admixtures and humic acids in carbons as well as the surface functional groups. Repeated cycles of lead sorption/elution indicated that the metal capacities of the carbon-packed mini-columns were reduced but reached a steady level after 3-4 cycles.
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Faherty, Cathy. "Removal of heavy metals from wastewater using polyelectrolyte chelates." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252332.
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Erdoğan, Demet Polat Hürriyet. "Removal of Heavy metals from wastewaters by ion flotation/." [s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/cevremuh/T000351.pdf.
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Chong, Brian S. H. "The removal of pesticides and heavy metals by reverse osmosis." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42126.
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Chuichulcherm, Sinsupha. "Configuration and operation of bioreactors for metal removal from wastewater systems using sulphate reducing bacteria." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249226.
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Mandadi, Keerthy. "Removal of Heavy Metals Using Modified Limestone Media: Zinc and Cadmium." TopSCHOLAR®, 2012. http://digitalcommons.wku.edu/theses/1170.
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Heavy metal contamination is a serious concern throughout the world. Increased concentrations in drinking water have many negative impacts on human health. Limestone is an inexpensive and simple media for removing high concentrations of heavy metals from drinking water supplies. Ferric based media is commonly used to remove zinc, cadmium, lead, arsenic and other heavy metals. The drinking water standards set by the US EPA for cadmium, zinc and arsenic are 0.005 mg/L, 5 mg/L and 0.010 mg/L respectively. Bangladesh, parts of India, China and the United States have high concentrations of arsenic in drinking water. Although many technologies exist for heavy metal removal, most of these are complicated and are associated with high costs making them ineffective and unfavorable to be used in impoverished areas.
We propose a novel method that combines the benefits of limestone with the capacity of ferric media in an iron-coated limestone based material. Samples of water with various concentrations of zinc and cadmium were prepared and batch tests were performed using both uncoated and iron coated limestone and are compared in removal efficiency. Kinetics studies showed that zinc is removed to a maximum level after 24 hours, while cadmium takes only 15 minutes. The effect of pH on removal of heavy metals was also studied. Metals are analyzed using Inductively Coupled Plasma Emission Spectroscopy (ICP-ES). Limestone is readily available and is also easy to coat with iron, making this material a cost effective and affordable method to be used by developing countries.
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Kapoor, Anoop. "Removal of heavy metals from aqueous solution by fungi Aspergillus niger." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0023/NQ30261.pdf.
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El-Ammouri, Elias G. "Heavy metals removal from effluents by adsorption on activated silica sols." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0031/NQ64552.pdf.
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Türkmen, Müşerref Ülkü Semra. "Removal of heavy metals from wastewaters by use of natural zeolites /." [S.l. : s.n.], 2001. http://library.iyte.edu.tr/tezler/master/cevremuh/T000028.pdf.
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Jan, Mir Ahmed. "Removal and recycling of metals from aqueous systems using fluidised bed electrolysis in combination with other concentrators." Thesis, Brunel University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366225.
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Zhao, Jingjing. "Valorization and reuse of waste modified biomass. Heavy metal biosorption removal from aqueous solutions." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667800.
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Les aigües contaminades per metalls pesants han rebut una atenció creixent a causa de la seva alta toxicitat, persistència en els sediments i acumulació biològica dels metalls pesants, sent una amenaça potencial per als sers vius, fins i tot a baixa concentració. Les tècniques tradicionals per eliminar metalls pesants són processos contaminants i de cost elevat, fet que limita les seves aplicacions. Així, és urgent trobar un mètode de baix cost, de bona eficiència i eco-friendly per fer front a aquest tipus de problemes. La biosorció pot ser una opció prometedora en aquest cas gràcies a mostrar bones eficiències i ser un material respectuós amb el medi ambient, emprant biomassa.
D'altra banda, hi ha gran quantitat de residus de biomassa al món els quals poden causar un problema ambiental si no es gestionen correctament. D’altra banda, la cel·lulosa, la hemicelulosa i la lignina són abundants en residus de biomassa. La presència de grups funcionals ben coneguts en aquests components naturals els converteixen en materials potencials per a la biosorció de metalls pesants.
Així, la biomassa s'ha emprat com adsorbent naturals permetent resoldre dos problemes ambientals: en primer lloc, l'eliminació de residus agrícoles (de biomassa agrícola) i, en segon lloc, la seva utilització com a adsorbents per a l'eliminació de metalls pesants procedents de les aigües residuals.
Amb aquest propòsit, s'utilitzen tipus diferents de biomassa i alguns dels seus biochars per eliminar els ions Cr(III), Cd(II), Cu(II) i Pb(II) a partir d'una barreja d’aquests. D’altra banda, les partícules de TiO2 també són un bon adsorbent per eliminar metalls pesants. El pi i el pi pirolitzat carregat amb TiO2 (Pine/TiO2) s'empren com a absorbents per eliminar els metalls pesants de les aigües. S'ha comprovat l'especiació de Cr(III) i Cr(VI) emprant els sistemes de biomassa/biochar del pi.
En tots els casos, s'optimitzen diferents paràmetres dels processos de biosorció en experiments en discontinu (el pH de la solució, la concentració inicial i el temps de contacte), i s’han ajustat tan models cinètics com d’isotermes per aclarir els possibles mecanismes d’adsorció. La morfologia superficial dels adsorbents s'analitza mitjançant microscòpia electrònica de rastreig (SEM) i espectroscòpia infraroja de transformada de Fourier (FTIR). A més, es realitza espectroscòpia d'absorció de raigs X (XAS) per estudiar el mecanisme de biosorció a nivell molecular.
La capacitat de biosorció de les biomasses avaluades es classifica de la manera següent: FO (residus de fangs de la indústria) > ZO (de l’agricultura, residus de biomassa de blat de moro) >> CO (residus de biomassa de fusta de pollancre). S'ha trobat que la complexació i l’intercanvi de cations són els dos principals mecanismes d’adsorció en sistemes que contenen mescla de metalls pesants, sent l’intercanvi de cations el més significatiu. Com a resum de l’estudi de l’especiació de crom realitzat per sistemes de biomassa/biochar de pi, els resultats mostren que l’adsorció de Cr(III) es fa principalment a través d’un intercanvi iònic amb els components minerals presents a les superfícies dels biomaterials. El procés de piròlisi pot augmentar la concentració d’aquests minerals per augmentar la capacitat d’adsorció. Per al Pi/TiO2, juntament amb l'intercanvi iònic també la complexació amb el catecol pot ajudar la biosorció Cr(VI). Des de mesures XAS es pot concloure que el procés d’intercanvi iònic amb grups carboxílics és el principal pas de biosorció, seguit de la reducció del crom.
Finalment, la utilització de biosorbents contenint metalls pesants com a materials de maó és una manera prometedora de resoldre el problema d’eliminació. Aquests biosorbents són materials prometedors que es poden aplicar a gran escala per tractar l'aigua contaminada del món.Polluted water contaminated by heavy metals has received increasing attention due to their high toxicity, persistence in sediment, and biological accumulation of the heavy metals, which lead to a potential threat to animals and human beings even at low concentration. Traditional techniques to remove heavy metal are high cost or making the second pollution that limited large-area applications. Most importantly, traditional techniques cannot apply to such low concentration in water. Therefore, it is emergency to find a low-cost, efficiency and eco-friendly method to deal with this kind of problem. Biosorption can be a promising option in this case due to its high efficiency and eco-friendly, especially the abundant materials in the world such as biomass. On the other hand, a huge amount of biomass waste in the world will cause an environmental problem if not handled properly. Furthermore, cellulose, hemicellulose and lignin are abundant in biomass wastes that can be employed as cheap adsorbents due to their special physical and chemical properties. The presence of well-known functional groups in these natural components turn them as potential materials for heavy metal interaction and subsequent removal. Therefore, biomass from agricultural wastes and wood industry have been checked as natural adsorbents to solve two serious environmental problems: firstly the disposal of agriculture wastes, and secondly its use as adsorbents for the removal of heavy metals from wastewaters. With this purpose, many different types of biomass feedstocks and some of their biochars are used to remove Cr(III), Cd(II), Cu(II) and Pb(II) ions from a mixture of multiple heavy metals. Furthermore, TiO2 nanoparticles are also a good adsorbent for removing heavy metals. Pine and pyrolyzed pine loaded with TiO2 (Pine/TiO2) have been used as sorbent for the removal of heavy metal ions from aqueous solution. Single and multi-element systems are used for the heavy metals removal. In addition, Cr(III) and Cr(VI) speciation has been checked for pine biomass/biochar systems. In all cases, different parameters of the biosorption processe are optimized in batch systems (pH of the solution, the initial concentration and the contact time), and kinetics and isotherm modelling have been performed to elucidate the possible biosorption mechanisms. Surface morphology of the adsorbents are analyzed using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Moreover, X-ray absorption spectroscopy (XAS) is performed to study the biosorption mechanism at the molecular level. The adsorption capacity of biomass is ranked as follows: FO (from industry sludge waste) > ZO (from agriculture corn biomass waste) >> CO (from wood poplar biomass waste). Complexation and cation exchange have been found to be the two main adsorption mechanisms in systems containing multiple heavy metals, with cation exchange being the most significant. As a summary of the chromium speciation study by pine biomass/biochar systems, the adsorption of Cr(III) is mainly through ion exchange with the mineral components present on the biomaterials surfaces. Pyrolysis process can increase the concentration of such minerals to increase the adsorption capacity. For Pine/TiO2, together with the ion exchange also complexation with catechol can help Cr(VI) adsorption. From XAS measurements it can be concluded that the ion exchange process with carboxylic site groups is the main biosorption step, followed by the chromium reduction. Finally, utilization of biosorbent loaded with heavy metal as brick materials is a promising way to solve disposal problem. These biosorbents are promising materials that can be applied in large scale to deal with the polluted water in the world.
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Tuzcu, Emrah Tugcan. "Removal Of Heavy Metals In Waste Water By Using Coal Fly Ash." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606366/index.pdf.
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In this research, it is aimed to remove toxic heavy metals in waste water with the help of fly ash from Çayirhan thermal power plant. The chemical and physical properties (size distribution, specific surface area, porosity, chemical composition, etc.) of fly ash were determined. The experiments were carried out in synthetic waste water containing lead, zinc and copper metals at different concentrations with the addition of fly ash. The effects of metal concentration, agitation time, particle size, ash amount, and pH in the metal removal were examined. With the addition of even very small amount of fly ash, heavy metal removal from waste water was attained at up to 99%. Fly ash particle size has no significant effect on removal of heavy metal ions from solutions. Higher solution pH and longer treatment time were resulted better metal removal. The results also indicated that the main mechanism for metal removal was precipitation due to alkaline characteristics of fly ash and more than 90 % of metals in solutions were removed by precipitation. The pH ranges for maximum metal precipitation were 10-11, 8-10, and 10-11 for copper, zinc, and lead respectively. Very small percentages of adsorbed metal was released during the desorption test.
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Yang, Shu. "Effects of heavy metals and phosphorus on nitrate removal in constructed wetlands." Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-15550.
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Amoyaw, Prince N. A. "Development of polymeric chelating ligands for removal of heavy metals from water." DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2008. http://digitalcommons.auctr.edu/dissertations/2082.
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Poly[4-(4-vinylbenzyloxy-2-hydroxybenzaidehyde)i and Po]y[1 -(2-pyridyl)-3-[4- (4-vinyihenzyloxy)phenyl]im.idazo( I ,5-a)pyridine-co-methacrylate] were synthesized and characterized and have been evaluated to he effective sorbent materials for [he removal of heavy metats from aqueous solution. Batch adsorption experiments were performed for several divalent metal ions, namely Pb24, Cd2t. Cu24, Ni2~, Zn2~ and Co2~. Preliminary batch adsorption screening test revealed that the adsorbents being evaluated had the highest adsorption capacities for Pb and Cd ions, hence they were studied in much greater detail. Upon applying the equilibrium data to the Langmuir and Freundlich isotherm models, the adsorption of the Pb ions on both the polymer and the copolymer fitted well to the Langmuir model. This means that there occurred homogeneous and. complete monolayer coverage of the Ph2~ ions on the polymer surface as well as on the copolymer surface.
Two kinetic models, pseudo-first-order and pseudo-second-order were also tested to investigate the adsorption mechanisms and the kinetics was found to be second order and equilibrium adsorption occurred within 15 seconds. This suggests that the adsorption sites are either near the adsorbent or on the adsorbent surface therefore the metal ions have easy access to them thereby resulting in a high frequency of collision between the metal ions and the adsorption sites. The metal removal was also found to be strongly dependent on pH and this is reflected in the gradual increase in percent adsorption as pH increases from 1.0 to 5.5.
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El-Shafey, El-Said Ibrahim Abdel-Hamid. "Removal of heavy metals on a carbon sorbent prepared from flax shive." Thesis, University of Hertfordshire, 2000. http://hdl.handle.net/2299/14068.
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Carbon is prepared from flax shive by treatment with sulphuric acid. The optimised conditions of preparation were based on metal sorption (Cd2+, Hg2+), carbon yield, and acid and energy consumption. The carbon product retains its fibrous woody texture and XRD indicates an amorphous structure which has a very low surface area determined by nitrogen adsorption. Elemental analysis of the sorbent shows a very low amount of sulphur (-1%), while FTIR shows the presence of carboxyl, carbonyl and hydroxyl (or phenolic) groups. Cadmium shows fast kinetics of sorption for this material reaching equilibrium within 3 hours and having a sorption capacity similar to the cation exchange capacity (CEC) and base neutralisation capacity data. On the other hand mercury shows slow kinetics with 120 hours equilibrium time. Sorption capacity for mercury was high compared to that of cadmium or the cation exchange capacity. Base neutralisation capacity shows that the sorbent prepared at 200°C (C200) possesses more carboxylic and hydroxyl groups than that prepared at 160°C (C 160) and agrees with the cation exchange capacity data and cadmium sorption. A comprehensive study for cadmium on C200 sorbent found that sorption increases with pH and decreases with the presence of other metal ions in the aqueous solution. Mechanism of sorption investigated by the ratio of [H+]/[Cd2+] on a molar basis gave a value -2 indicating an ion exchange mechanism. Other metals such as Coe+, Cri+, Cue+, Nie+, Pb2+ and Zn 2+ were found to behave in a similar way to cadmium. These metals show fast kinetics with C200 reaching equilibrium within 3 hours. The ratio of metal sorbed on C160 to that on C200 is similar to that of cadmium and also to the ratio of CEC C 160/CEC C200. Such results suggest that these metal ions are sorbed via an ion exchange mechanism onto sites such as carboxylic and hydroxyl groups. Sorption was found to fit the Langmuir equation with an insignificant increase with temperature. Column studies proved that C200 can be used several times to sorb Cd 2+ from aqueous solution and using 0.5 mol/dm3 sulphuric acid as a stripping solution. On the other hand, mercury behaves differently showing, in addition to slow kinetics, a much higher uptake. This suggests that mercury sorption is not only an ion exchange mechanism. Such slow kinetics were found to follow a first order rate equation and the sorption data also fits the Langmuir equation. Wet samples showed a higher sorption than one that had been previously dried. Other metals such as Au (III), Cr (VI), Pd (II), Ag (I), Pt (II) and Pt (IV) were found to behave similarly to Hg (II) following the Langmuir equation with higher uptake with increasing temperature and also showing slow kinetics. The kinetics of uptake of these metals follows the first order rate equation and during the sorption process these metals were reduced. In addition, Mn04_ was converted to Mn02 and Mn2+; Fe 3+ to Fee+and Cr6+ reduced to Cr3+ which was then sorbed via an ion exchange process. Also, and depending on the initial pH, the kinetics of sorption of Cr6+ was found to follow a second order rate equation at pH 4.5, while starting at pH 1.5, chromium reduction follows a first order rate equation. Sorption of this group of metals depends on the pH of the aqueous solution. Hg 2+ sorption shows maximum uptake in the pH range 6-7 while Cr6+ shows maximum sorption within pH range 2.2-2.6 depending on the sorbent state (wet, dry) and the concentration of Cr6+. Reduction of Hg2+ to Hg2CI2 and elemental mercury was confirmed with the observation of deposits on the carbon surface from SEM photographs. X-ray powder diffraction (XRD) showed that the crystals formed on the carbon surface are mercury (I) chloride. Some other metal species such as AuC14", PdC12,A gNO3 and PtC142"showedre duction on the carbon surface to their elemental forms as observed on the SEM photographs and confirmed by XRD. Reduction of the metals was followed by the formation of new carbon-oxygen groups on the surface and also evolution of carbon dioxide. PtC162' does not show any reduction on the carbon surface suggesting the possibility that the carbon reduction potential is perhaps very close to +0.7V. This material seems to be an efficient alternative for activated carbon sorbents to remove and recover heavy metals from waters, with added advantages for those metals which can be reduced to the elemental form.
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Karanjkar, A. M. "Biofilm modified activated carbon surfaces for removal of heavy metals and organics." Thesis, University of Bath, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261160.
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Ezzeddine, Zeinab. "Divalent heavy metals adsorption on various porous materials : removal efficiency and application." Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2315/document.
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L'accès à l'eau potable est indispensable au développement de la vie. La pollution, liée aux activités anthropiques, constitue une menace pour la santé humaine et pour les espèces sauvages. Parmi les nombreux polluants retrouvés dans les eaux, la pollution par les métaux lourds constitue un problème environnemental d'intérêt mondial en raison de leur toxicité élevée, même à des concentrations très faibles, et de leur persistance dans la nature. De nombreuses méthodes peuvent être mises en oeuvre pour l'élimination des métaux lourds dans l'eau. Parmi elles, les procédés d'adsorption sont très attractifs car très efficaces et peu couteux. Les zéolithes sont des matériaux bien connus pour leurs propriétés d'échange. Les matériaux mésoporeux modifiés ou adsorbants carbonés sont également très attractifs du fait de leur importante surface spécifique. Dans ce manuscrit, les performances d'adsorption de cations métalliques en phase aqueuse sur des matériaux mésoporeux, silices SBA-15, SBA-16, KIT-6 modifiées par l'EDTA et carbone CMK-3 obtenu par réplication ont été étudiées et comparées avec celles de la zéolithe NaX. Les propriétés physico-chimiques de l'ensemble des matériaux ont été caractérisées par plusieurs techniques d'analyses. L'influence des paramètres expérimentaux (pH, temps de contact, température, concentration des ions métalliques et de la présence d'ions concurrents) sur l'adsorption a été étudiée en mode batch. L'efficacité de ces matériaux a également été étudiée dans un réacteur dynamique à lit fixe. Les résultats obtenus ont montré que tous les matériaux étudiés éliminent efficacement et rapidement les métaux divalents dans les eaux même à faible concentration. Néanmoins, le carbone CMK-3 s'avère être le meilleur adsorbant du fait de sa grande capacité d'adsorption même en présence d'espèces compétitricesAccess to sustainable and clean drinking water is a main concern as the Earth's human population continues its steady growth. Unfortunately, many of the available water resources are becoming increasingly polluted as a result of the direct discharge of industrial effluents. Heavy metals pollution, in particular, is an environmental problem of global interest due to their high toxicity, even at very low concentrations, and persistence in nature. Many methods are available for metal ions removal including adsorption which is attracting a lot of attention recently. Zeolites are well known for having very high exchange capacities. On the other hand, many researchers are studying the removal of heavy metals by modified mesoporous materials or carbonaceous adsorbents. In this thesis, the adsorption efficiencies of several materials for heavy metal removal in aqueous phase were investigated and compared to those of the faujasite NaX zeolite. Mesoporous silica SBA-15, SBA-16, KIT-6 were synthesized and modified with EDTA. Moreover, CMK-3 carbon was nano-casted from SBA-15 then the physic-chemical properties of these materials were characterized by different techniques. The effects of several experimental conditions on adsorption such as pH, contact time, temperature, metal ions concentration and the presence of competitors were studied in batch experiments. Then the efficiency of all these materials was also studied in a dynamic fixed bed reactor. Based on the obtained results, it could be said that all these materials are good candidates for divalent heavy metals removal from waste water even at low concentration. However, CMK-3 material has a high sorption capacity even in presence of competitor species
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Al, Rashdi Badriya Abdullah. "Removal of heavy metals from a concentrated aqueous solution : adsorption and nanofiltration techniques." Thesis, Swansea University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678557.
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Dietrich, Theo Henry. "The removal of heavy metals from dilute aqueous streams by the use of ion exchange resins." Thesis, Cape Technikon, 1998. http://hdl.handle.net/20.500.11838/887.
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Thesis (MTech (Chemical Engineering)--Cape Technikon, Cape Town, 1998Ion exchange resins are widely used to remove or concentrate heavy metals from aqueous solutions or slurries.This thesis attempts to properly evaluate the interaction between ion exchange resins and heavy metals at trace metal concentrations.The durability of the resins and their effectiveness in real slurries were also investigated. In this study, a chelating resin, as well as a cation, and anion exchange resin was contacted with aqueous solutions of heavy metals in both free and complexed form. Zinc, nickel and copper cyanide complexes were adsorbed onto the anion exchange resin, while the chelating and cation exchange resins were contacted with zinc and nickel nitrates, and cupric sulphate. All the tests were conducted in batch stirred tank reactors. All the metal cyanide complexes behaved in a similar manner when contacted with the anion exchange resins. These tests were p~rf0nned under variations in temperature, stirring speed, pH., ionic strength and . initial metal 90E~entrations. Fitting of a dual resistance model to the profiles for thetlptllk:e" of the complexes, show that both film diffusion and intraparticle diffusion rates were improved with an increase in temperature, and that film diffusion rates improved with an increase in stirring speed. A high ionic strength negatively affected equilibrium loading as well as diffusional rates.It was found that at these low concentrations, the diffusional rates improves with a decrease in the external metal concentration. A comparative study involving the chelating and cation·exchange resins were performed, during which the resins were contacted with the metals in free fonn. It was found that at high metal concentrations, the chelating resin induced a rate limiting effect, but at trace concentrations, this effect is virtually negated. Whereas the cation exchange resin exhibited little selectivity in adsorbing the metals, it was found that the chelating resin prefers the metals in the eu > Ni > Zn. The chelating resin proved to be no less durable then the cation exchange resin, and both slightly lost their ability to adsorb the metal cations as a result of the effects of an inert coarse sand slurry.Tests performed with a real ore leachate, showed the cation exchange resin to be efficient at a low pH , but also relatively non selective, since the adsorption of copper from the leachate was greatly reduced due to the presence of other heavy metals.
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Nordin, Andreas. "Heavy metal removal from sewage sludge by pyrolysis treatment." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-8807.
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Sewage sludge is the product from wastewater treatment that mostly is considered as a waste material. However, it contains several nutrients, especially phosphorus, potassium and nitrogen which are excellent fertilizers. The downside is the harmful content it also carries with pathogens, heavy metals and a variety of organic pollutants that in many cases have unknown effects on the ecosystem. A possible solution to this problem could be to pyrolyse the sewage sludge and by that decrease the levels of heavy metals and also render both pathogens and organic pollutants harmless. In this thesis project pyrolysis of dried sewage sludge has been evaluated at temperatures 650 750, 850 and 950 °C with addition of chlorine in the form of PVC and straw. An energy balance for pyrolysis and drying of dewatered sewage sludge has also been suggested. The results of the pyrolysis evaluation indicate that cadmium concentration can be reduced significantly with increasing temperature in the product char. But also other heavy metals like lead and zinc are affected at the higher temperatures evaluated. Mercury is completely removed from the char residue. The more latent volatile metals copper, chromium and nickel cannot be reduced to lower concentrations at these temperatures. They are instead enriched under these conditions. Chlorine addition to the sludge enhances the evaporation of all heavy metals but copper, nickel and chromium. The energy balance over the system indicates that the drying process requires more energy than is released from the sludge into the pyrolysis gases. The energy carried by the pyrolysis gases is however larger than what is required to drive the pyrolysis process.
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Ngule, Chrispus M. Jr. "In Vitro Adsorption of Heavy Metals Using Metal-Organic Frameworks." Youngstown State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1597664070125999.
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Zanain, Mabrouk Ali Masaud. "Removal of low concentrations of silver from aqueous solutions using adsorption methods." Thesis, Swansea University, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678471.
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De, Haro del Rio David. "Synthesis and characterisation of hierarchical zeolitic materials for heavy metals adsorption." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/synthesis-and-characterisation-of-hierarchical-zeolitic-materials-for-heavy-metals-adsorption(5e4e90db-59b7-4d15-b284-32e179ff1e94).html.
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This thesis explains a method based on the homogenisation of zeta potential charges on carbon supports for the production of hierarchical structured zeolitic composites. The modification of carbons’ surface chemistry allowed zeolite particles to be fixed to the support by electrostatic interactions. In order to achieve this, the size reduction of zeolite particles was carried out by two different methods: a) ball milling and b) a synthetic route to produce zeolite colloidal dispersions. Also, the seeding method, based on hydrothermal growth was compared. The prepared materials in this work were designed to be used in the sorption of cations, and to allow vitrification and thereby reduce the final adsorbent volume. Results showed that a large pollutant amount can be trapped using a lower volume of material reducing costs and final waste disposal. The zeolites used in this work were selected based on their low density framework and low Si/Al ratio. Synthetic zeolites A, Y and clinoptilolite were successfully produced. Natural clinoptilolite was also utilised in this work. Also, zeolite A was produced at nanometre scale following the clear solutions method. All materials were successfully incorporated onto supports to produce multimodal porosity materials. The hierarchical modification of natural clinoptilolite, following a straightforward and nonexpensive methodology, is one the most significant contributions of this work. Carbons are used as supports due to their high surface area, they can be obtained from low-cost sources such as agroindustrial wastes and carbons allow volume reduction if materials are vitrified at high temperatures. In this work, carbons were produced from corn cob and husk, sugar cane bagasse, cherry stones, date stones and hazelnut shells. The prepared composite materials were tested in the removal of toxic ions from water solutions: cobalt, copper and caesium ions were effectively removed from aqueous media. Adsorption experiments showed that the distribution of supported zeolite particles improved their uptake efficiency and capacity. The kinetic studies revealed an enhanced rate constant for carbon-zeolites composites in comparison with pure zeolites. Diffusivity results suggested that mass transfer characteristics are modified by using hierarchical porous materials; results showed that particle size or support nature can modify diffusion resistances, reducing intraparticle diffusion and accelerating the overall kinetic processes. Adsorption equilibrium data was correlated using Langmuir and Freundlich models.
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Tudury, Heloisa Andrade de Paula. "The use of hatchery residual biosorbent for removal of heavy metals from wastewater." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3643.
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Thesis (M.S.) -- University of Maryland, College Park, 2006.Thesis research directed by: Dept. of Civil and Environmental Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Selepe, Mamaropeng Marcus. "The removal of toxic heavy metals from aqueous solutions by algal extracellular polysaccharides." Thesis, Rhodes University, 1999. http://hdl.handle.net/10962/d1004054.
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This study investigated the possible use of algal extracellular polysaccharide as a biosorbent for removal of heavy metals (copper and lead) from aqueous solutions as a means of bioremediation for metal containing effluents. This biopolymer has good biosorbent properties and a potential to provide a cost effective, selective and efficient purification system. A variety of environmental conditions induce the production of extracellular polysaccharides in algae. The production of exopolysaccharides by Dunaliella cultures was induced by nitrogen deficient conditions. A high ratio of carbon to nitrogen source considerably enhanced the polysaccharide release. Purified extracellular polysaccharide samples exhibited a monosaccharide composition consisting of the following sugars: xylose, arabinose, 2-0-methyl mannose, mannose, glucose and galactose. The relative abundance (%) of these sugars were calculated relative to xylose. The major sugar constituent was 2-0-methyl mannose, which was present at approximately 160% relative to xylose. The percentage relative abundance of other sugars was as follows: 18.8; 86.8; 85.3 and 22.3% for arabinose; mannose; glucose and galactose respectively. The identity of the various constituents were confirmed by mass spectrometry. The ability of Dunaliella exopolysaccharides to accumulate metals was investigated. The following parameters were studied because they affect metal uptake: solution pH, biomass concentration, temperature, time and metal concentration. The uptake of both copper and lead were pH dependent. However, metal uptake was not significantly affected by temperature. Kinetic studies showed that Dunaliella extracellular polysaccharides exhibit good bioremediation properties. Metal uptake was rapid. In addition, the exopolysaccharide has good metal binding capacity with an uptake capacity for lead of 80 mg/g from a solution containing initial lead concentration of approximately 40 mg/l. Competition studies revealed that the presence of a second metal in solution inhibits uptake of the other metal compared to uptake in single metal solution of that particular metal. The presence of lead inhibited the uptake of copper from approximately 65% in single metal solution to 10% in binary metal solution. The presence of copper also inhibited lead uptake, though not to the same extent. Higher concentrations of lead could not completely prevent removal of copper from solution and visa versa. The same was true for lead which could not be displaced by a four-fold concentration of copper. Instead, a certain percentage of copper was always removed showing that lead did not compete with copper for these binding sites. In conclusion it appears that, copper and lead bind to different sites on Dunaliella exopolysaccharides and that they exhibit selective or preferential removal of lead.
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Ntuli, Themba Dominic. "Preparation of chemically modified Macadamia nutshells for adsorptive removal of selected heavy metals." Thesis, Vaal University of Technology, 2017. http://hdl.handle.net/10352/379.
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M. Tech. (Chemistry, Faculty of Applied and Computer Science), Vaal University of TechnologyThe abundance of agricultural waste materials has led to its use as adsorbents for trace metal adsorption. The raw Macadamia nutshell (RMN) powder was treated with a hydrochloric acid solution to obtain acid modified Macadamia nutshells (AMM), and with sodium hydroxide solution to obtain base modified Macadamia nutshells (BMM). Then, the AMM and BMM materials were grafted with 0.5 M, 1 M, and 2 M acrylic acid. The different AMM grafted materials were labelled 0.5 GAM, 1 GAM and 2 GAM representing the different grafting ratios. The same naming order was followed for the BMM grafted materials, that is, 0.5 GBM, 1 GBM and 2 GBM corresponding to different concentrations used. The prepared Macadamia based adsorbents were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), carbon, hydrogen, nitrogen and sulphur (CHNS) analysis, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis. The determination of surface properties such as the point of zero charge (pHPZC), bulk density and the surface negative charge was accomplished with appropriate wet chemistry methods. The adsorption of selected trace metals (Cu(II), Cd(II), Co(II), and Cr(VI)) was done in batch experiments. Atomic absorption spectroscopy (AAS) was used for the determination of metal ions concentrations and total Cr. The ultraviolet-visible (UV–Vis) spectroscopy was used for the determination of Cr(VI) concentration remaining in solution after adsorption. The RMN, AMM, and BMM adsorbents showed potential in removing more than 45% Cu(II) ions, but less than 30% for both Cd(II) and Co(II) ions. However, more than 90% removal of Cr(VI) ions was achieved with the same adsorbents. Consequently, only the adsorption of Cr(VI) was further investigated in the study due to the higher removal efficiency displayed by the Macadamia based biosorbents. The optimum adsorption conditions for the RMN, AMM, and BMM materials were found to be pH 2, 100 mg/L initial concentration of Cr(VI), 600 min contact time and 0.2 g adsorbent mass. The ideal conditions for the 0.5 GAM and 0.5 GBM were found to be pH 2, 25 mg/L initial concentration of Cr(VI), 180 min contact time, and 0.15 g adsorbent mass. The optimum temperature was found to be 40℃ for all materials. A volume of 20 mL was used for all batch experiments. The RMN, AMM, BMM, 0.5 GBM, and 0.5 GAM adsorption mechanisms were better described by the Langmuir isotherm which predicted a monolayer sorption process. The kinetic data fitted better to the pseudo second-order rate model which signified a chemisorption type of interaction. The thermodynamic parameters showed that the adsorption reaction was feasible, spontaneous and endothermic. The Macadamia based materials showed greater potential as adsorbents for the adsorption of Cr(VI) ions from aqueous solution compared to the other selected trace metal ions [Cd(II), Cu(II) and Co(II)].
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Lima, Daniel David de. "AvaliaÃÃo da remoÃÃo de metais pesados em efluentes industriais por sulfeto quÃmico e biogÃnico." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10570.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoO presente estudo teve o objetivo de avaliar a remoÃÃo de metais pesados em efluentes industriais pelo uso de sulfeto quÃmico e biogÃnico. Inicialmente, foi operado, sob condiÃÃes mesofÃlicas (27  2 ÂC), um reator anaerÃbio de manta de lodo e fluxo ascendente (VÃtil = 2,7 L; TDH = 24 h) suplementado com sulfato (em relaÃÃes DQO/SO42- de aproximadamente 10 e 5) para a produÃÃo de sulfeto biogÃnico. Posteriormente, o efluente das indÃstrias de folheaÃÃo de joias da cidade de Juazeiro do Norte, CearÃ, foi caracterizado para verificar os principais metais contidos e suas faixas de concentraÃÃes, alÃm de outros constituintes. Em seguida, analisou-se a aplicaÃÃo de planejamento experimental multivariado cujos fatores estudados foram concentraÃÃo de metal (20, 80 e 140 mg/L), concentraÃÃo de sulfeto (20, 40 e 60 mg/L) e tempo de reaÃÃo (1, 5 e 9 min), no processo de remoÃÃo dos metais cobre, zinco e nÃquel, tanto na presenÃa quanto na ausÃncia de macro e micronutrientes. Finalmente, foi verificada em experimentos univariacionais a influÃncia das condiÃÃes operacionais tempo de reaÃÃo (15 e 30 min), razÃo molar metal/sulfeto (0,5; 0,7; 1; 1,6; 1,75 e 2) e fonte de sulfeto (quÃmico e biogÃnico) na eficiÃncia de remoÃÃo dos metais pesados analisados. ApÃs a caracterizaÃÃo do efluente das indÃstrias de folheaÃÃo de joias constatou-se que os metais majoritÃrios foram cobre, nÃquel e zinco. O reator sulfetogÃnico apresentou operaÃÃo estÃvel para as relaÃÃes DQO/SO42- estudadas, com remoÃÃo de DQO superior a 70% e reduÃÃo de sulfato acima de 90%. A partir do planejamento experimental multivariado, observou-se que o fator mais significativo foi a concentraÃÃo de metal para todos os casos, sendo que, para o cobre, a concentraÃÃo de sulfeto nÃo teve efeito significativo na presenÃa de macro e micronutrientes. Por sua vez, para o nÃquel, constatou-se que todos os fatores exercem influÃncia sobre a eficiÃncia de remoÃÃo. Jà para o zinco, o tempo nÃo teve influÃncia significativa na ausÃncia de macro e micronutrientes, enquanto que na presenÃa dos mesmos tal variÃvel apresentou significÃncia. Em seguida, nos experimentos univariacionais verificou-se que o tempo de reaÃÃo nÃo influenciou a remoÃÃo de metais estudados. A fonte de sulfeto apresentou efeitos diversos assim como a relaÃÃo molar metal/sulfeto. Por exemplo, com o cobre, em razÃes molares metal/sulfeto menores que 1,6, foram obtidas as maiores diferenÃas na eficiÃncia de remoÃÃo chegando atà 70%. Jà para o zinco, sà foram observadas algumas diferenÃas para razÃes molares acima de 1,6. Finalmente, para o nÃquel, alguma diferenÃa sà foi verificada para razÃes de atà 1.
The present study aimed to assess heavy metals removal from industrial effluents by using chemical and biogenic sulfide. Initially, an upflow anaerobic sludge blanket reactor (working volume = 2.7 L, HRT = 24 h), supplemented with sulfate (COD/SO42- ratio of approximately 10 and 5), was operated under mesophilic conditions (27 Â 2 ÂC) for biogenic sulfide production. Subsequently, the effluent of jewelry plating industries from the city of Juazeiro do Norte, CearÃ, was characterized in order to verify the major metals and their concentration ranges, as well as other constituents. Then, the application of a multivariate experimental design, whose factors were metal concentration (20, 80 and 140 mg/L), sulfide concentration (20, 40 and 60 mg/L) and reaction time (1, 5 and 9 min), in the process of copper, zinc and nickel removal, both in the presence and absence of macro and micronutrients, was analyzed. Finally, in univariate experiments, the influence of the operating conditions, such as reaction time (15 and 30 min), metal/sulfide molar ratio (0.5, 0.7, 1, 1.6, 1.75 and 2) and sulfide source (chemical and biogenic), on the removal efficiency of the tested heavy metals was verified. After the characterization of the jewelry plating industries effluent, it was found that the majority metals were copper, nickel and zinc. The sulfidogenic reactor showed stable operation for the COD/SO42- ratios studied, with COD removal higher than 70% and sulfate reduction above 90%. From the multivariate experimental design, the most significant factor was metal concentration in all cases. For copper, sulfide concentration had no significant effect in the presence of macro and micronutrients. However, for nickel, all the factors have an influence on removal efficiency. And, for zinc, the time had no significant influence in the absence of macro and micronutrients, whereas, in their presence, that variable was significant. From the response surface contour plot, the optimum point, in terms of removal efficiency, obtained for nickel in the presence and absence of macro and micronutrients was [Ni2+] = 140 mg/L, [S2-] = 60 mg/L and t = 1 min. Subsequently, in the univariate experiments, it was found that the reaction time did not affect the removal of metals studied. The sulfide source had different effects as well as the metal/sulfide molar ratio. For example, for copper, at metal/sulfide molar ratios lower than 1.6, the greatest differences in removal efficiency were obtained, which reached up to 70%. However, for zinc, some differences were only observed at molar ratios above 1.6. Finally, for nickel, differences were observed for molar ratios below 1.
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Whitehead, Kate. "The application of synthetic zeolites for the removal of heavy metals from contaminated effluents." Thesis, University of Surrey, 2000. http://epubs.surrey.ac.uk/771884/.
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The aim of this research was to provide a comprehensive evaluation of the heavy metal removal performance of two synthetic zeolites, Zeocros CA150 and Zeocros CG180. Detailed laboratory investigations of the key parameters known to affect zeolitic ion exchange were performed with respect to lead, zinc, copper, cadmium and nickel by means of batch equilibrium tests. The study into the effect of contact time suggests that a near equilibrium state was reached within two hours. As metal hydroxide precipitation was minimal at pH 6.0 and the structural integrity of the zeolite was maintained, metal removal at this pH is predominantly by ion exchange rather than chemical precipitation. Fluctuations in both silicon and aluminium release from the zeolites suggest that partial dissolution may occur under mildly acidic conditions, an observation discussed elsewhere in the literature. Heavy metal removal decreased with increasing metal loading, with the zeolites exhibiting Significantly lower operating exchange capacities compared to the theoretical ones. Exchange capacities varied between 1.3-4.9 meq/g and 0.5-4.6 meq/g for CA 150 and CG180 respectively for the five metals studied. Throughout all of the experimental investigations, lead was removed preferentially (>99%) and nickel removal effiCiencies were the lowest «20%). The results from the mixed metal studies demonstrated that lead removal was the least affected by the presence of other heavy metals whereas cadmium, copper and zinc removal was suppressed in comparison to that from Single metal solutions. The presence of competing ions was not found to adversely affect lead removal by CA 150 and CG180, with copper and cadmium removal showing the most suppression in the presence of calcium, magnesium, potassium and sodium. Zinc uptake by both zeolites proved the most sensitive to the addition of hardness ions even under soft water conditions. The zeolites were also demonstrated to achieve up to 100% removal from real effluents, outperforming a natural zeolite, clinoptilolite. Overall, this research has demonstrated the considerable potential of these synthetic zeolites to selectively remove heavy metals from complex contaminated effluents, indicating their possible application as a tertiary technology for effluent treatment.
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Rafida, Abdulsalam. "Removal of heavy metals in vertical flow biofilters conditioned with sulphate reducing bacteria (SRB)." Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430633.
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Xie, Ting 1971. "Heavy metal removal from soil by complexing reagents with recycling of complexing reagents." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30838.
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Heavy metals in the environment are a source of some concern because of their potential reactivity, toxicity, and mobility in the soil. Soil contamination by metals is placing human and environmental health at risk through possible contamination of food chain.Soil washing can be used to remove metals from the soil. Chemical treatment involves the addition of extraction agents that react with the contaminant and leach it from the soil. The liquid, containing the contaminants, is separated from the soil resulting in a clean solid phase. Six chelating reagents, EDTA, Citric acid, ADA, DTPA, SCMC, and DPTA, were employed to determine the relative extraction efficiencies of the six chelating reagents for the target metals. Recycling of chelating reagent was the main interest of this study. The experiments were divided into four parts: (1) preliminary studies on the preparation and characterization of soil that included grinding, sieving, soil texture measurements, total metals content post digestion and the distribution of metals in different soil fractions as well as (2) a comparison of the extraction efficiencies of six chelating reagents toward Cu, Pb, Zn, Fe, and Mn. Additionally, the chelating reagent was liberated and recycled by treatment of the metal-complexes with disodium diethyl dithiocarbomate (DEDTC). Additionally, supercritical CO2 was used to extract metal-DEDTC complexes using various surfactants to maintain the metal-DEDTC complexes in suspension. Finally, (4) magnesium metal was evaluated as an alternative method for liberating the water-soluble chelating reagent from the complex so as to be able to recycle this reagent as well.
The different approaches were promising in terms of recycling the chelating reagents that suggests a means of optimizing the experimental conditions in future applications.
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Chamoun, Ninus, Viktor Kjellvertz, William Mahajan, and Yuanchao Song. "Fate of Heavy Metals in Waste to Energy (WtE) Processes." Thesis, KTH, Skolan för kemivetenskap (CHE), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208925.
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This study was made to increase the understanding of how heavy metals in the aqueous phase are removed at low initial concentrations in different pH and Eh values. The reaction that has been studied is mainly hydroxide precipitation and adsorption in a condensate treatment. In the study, data from one of Vattenfalls waste incinerators was analysed and the results from the data were then compared to previous studies. To increase the understanding, modelling of the heavy metals behaviour in the given concentrations was then made with Medusa and PHREEQC. The heavy metals that were analysed were Sb, As, Pb, Zn, Cr, and Cd. The low initial concentration that vary between 36.1-23600 μg/l complicates the removal process because it corresponds in a low driving force and the results are hard to compare to other studies since the initial concentrations vary between 10-100 mg/l. From the modelling and the measurement data it can be seen that Pb, Zn, Cr, and Cd was removed by hydroxide precipitation at pH 10. According to the speciation calculations, the dominant species at this pH are Pb(OH) 2 , Cd(OH)2, Zn(OH)2 and Cr(OH)3. For arsenic a clear conclusion could not be drawn from the modelling and the measurement data because of low precision. Due to the limited thermodynamic parameters of antimony in comparison with other heavy metals in the database of Medusa and PHREEQC, the modelling of antimony behaviour in condensate treatment has relatively larger uncertainty is low. The modelling results show that the main species in acidic solutions for antimony is Sb(OH)3 and in basic solutions Sb(OH)-6. Further investigation for antimony in needed for a clear conclusions to be drawn
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Shumba, Trust. "Removal of heavy metals from CRUD and slime dam material using soil washing and bioremediation." Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/1536.
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Thema, Force Tefo. "Synthesis and characterization of graphene and carbon nanotubes for removal of heavy metals from water." Thesis, Vaal University of Technology, 2012. http://hdl.handle.net/10352/459.
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M-Tech. (Department of Chemistry, Faculty of Applied and Computer Science), Vaal University of Technology.The commercial flake graphite was prepared into functionalized graphite oxide (GO) by adopted chemical treatment. After the exfoliation and intercalation of graphite into functionalized graphene oxide that formed stable colloidal dispersion in polar aprotic solvent, the reduction process was undertaken by continuous stirring with hydrazine hydrate in a microwave at 35 oC for two hours. The reduced material was characterized by X-ray diffraction (XRD), attenuated total reflectance (ATR) FT-IR, Ultra-violet visible (UV-vis), atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman microscopy and magnified optical microscopy that confirm the oxidation of graphite and reduction of graphene oxide into graphene sheets. Carbon nanomaterials were synthesized from Co-Sn, Co-Sr and Co-Zn as catalysts supported on Al2O3, CaCO3 and MgO. The as-prepared nanomaterials were characterized by thermogravimetric and derivative thermogravimetric analysis (TGA & DTA), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and the transmission electron microscopy. The intensity ratios (ID/IG) of the D- and G- bands were found to be the same that is averagely at 0.83. The TGA & DTA curves have shown Co-Sn/Al had significant weight loss, Co-Sr/Mg weight loss and decomposition, Co-Sr/Al decomposition and Co-Zn/Mg weight loss. However these weight losses were not significant. The EDS analysis showed all elements which took part in the reaction confirming the success of each synthesis. The SEM images show carbon nanotubes only on samples that have been synthesized on MgO as confirmed by TEM images. Finally the XRD showed some characteristic peaks at desired peaks except that they were other peaks attributed to impurities and armophous carbon. It was also observed that Co-Sn/Ca and Co-Sn/Mg XRD curves showed broad peaks at theta = 24.3o & 42.6o and theta = 23.9o & 43.1o respectively which are lattice structure characteristic peaks.
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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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Mulligan, Catherine N. "On the capability of biosurfactants for the removal of heavy metals from soil and sediments." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0017/NQ44526.pdf.
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Castellan, Paolo. "The role of chelating agents and soil pH on heavy metals removal from contaminated soil." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23873.
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Batch washing experiments were used to evaluate extractive decontamination of heavy metal polluted illite soils using ethylenediamine-tetraacetic acid (EDTA) and trans 1,2 cyclohexylenedinitrilo-tetraacetic acid (CDTA). Five series of contaminated illite soils were prepared through adsorption tests using four single-specie 5000 ppm heavy metal solutions of Pb, Cu, Zn, or Cd and one multi-species solution containing 1250 ppm of each heavy metal. The five contaminated illite soils that were prepared contained the following levels of heavy metals per kilogram of soil: (i) 5000 mg Pb, (ii) 3490 mg Cu, (iii) 1566 mg Zn, (iv) 700 mg Cd, (v) 1186 mg Pb; 379 mg Cu; 151 mg Zn; and 125 mg Cd. The soil washing results revealed that EDTA and CDTA are equally effective in releasing heavy metals from the contaminated illite soils, with removal efficiencies ranging from 35% to 99% for the 10$ sp{-5}$ M and 10$ sp{-1}$ M solutions, respectively. The optimum pH range for all chelate concentrations and all heavy metal contaminants is between 3-5. Competition between heavy metals in the soil for the adsorption sites of EDTA and CDTA did not have an impact on the removal efficiencies attained. In addition, the heavy metal preferential adsorption sequence demonstrated by the illite soil was $ rm Pb>Cu>Zn>Cd$ for the single-specie pollutant solutions and $ rm Pb>Cu>Zn approx Cd$ for the multi-species heavy metal pollutant solution, and were shown to be mainly bound to the carbonates and Fe and Mg oxides.
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Esalah, Jamaleddin. "Removal of heavy metals from aqueous solutions by precipitation with sodium di-(n-octyl) phosphinate." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37715.
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Two organophosphorus compounds: sodium di-(n-octyl) phosphinate and sodium di-(n-dodecyl) phosphinate, were synthesized and purified. Sodium di-(n-octyl) phosphinate was used both as a surfactant to form reverse micelles and as a precipitating agent to remove heavy metals from aqueous nitrate and chloride solutions.The heavy metals lead, cadmium, and zinc were precipitated from aqueous solutions with sodium di-(n-octyl) phosphinate (NaL) in the form of PbL 2(s), CdL2(s), and ZnL2(s). The mole ratio of NaL to lead in the feed was varied from 0.1 to 6.5, depending on the acidity of the feed. The effects of the feed pH, concentration of chloride, concentration of calcium, and of the chain length of the precipitating agent on the removal of lead, were investigated. Adding acid to the feed solution reduced the removal of lead as some of the phosphinate precipitated in the acid form as HL(s). The presence of chloride or calcium in the feed solution, up to mole ratios to lead of 250 and 2.75, respectively, had no effect on the removal of lead. The solubility of the precipitate PbL 2(s) was reduced by increasing the length of the alkyl group of the phosphinate. The removal of cadmium, zinc, and a mixture of lead, cadmium and zinc was investigated. Behavior similar to that of lead was observed. The selectivity of the precipitating agent for the three metals was in the order Zn > Pb > Cd.
The precipitating agent was completely regenerated by adding NaOH to the precipitate, and then contacted with diethyl ether to extract the reagent. The lead was completely recovered from the PbL2(s). Pure lead-free precipitating agent, and an aqueous solution of lead at a concentration 100 times its concentration in the feed, were obtained.
Using measured solubility products of the precipitates and literature values of the stability constants for the other expected reactions, the removal of metal, the loss of precipitating agent, and the equilibrium pH were predicted.
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Mulligan, Catherine. "On the capability of biosurfactants for the removal of heavy metals from soil and sediments." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35023.
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Batch soil washing experiments were used to evaluate the feasibility of using biosurfactants for the removal of heavy metals from a contaminated soil and sediments. Surfactin from Bacillus subtilis, rhamnolipids from Pseudomonas aeruginosa and sophorolipid from Torulopsis bombicola were evaluated using a soil contaminated with hydrocarbon and metals (890 mg/kg zinc, 420 mg/kg copper, 12.6% oil and grease) and metal contaminated sediments (110 mg/kg copper, 3300 mg/kg zinc).Although water alone removed insignificant levels of metals, results showed that the biosurfactants could remove 5% of the zinc (with 12% rhamnolipid) and 19.5% of the zinc (with 4% sophorolipid with 0.7% HCl). Copper could also be removed and was most efficiently extracted (greater than 25%) with 12% rhamnolipid or with 2% rhamnolipid with 1% NaOH. 1% NaOH alone removed only 5% of the copper and 2% zinc. After a series of five batch washes, 90% of the copper could be removed by 0.1% surfactin with 1% NaOH while 4% sophorolipid with 0.7% HCl was able to remove 100% of the zinc. From the sediment, a single washing with 0.5% rhamnolipid removed 65% of the copper and 18% of the zinc whereas 4% sophorolipid removed 25% of the copper and 60% of the zinc.
Sequential extraction procedures were used on the soil and sediments. For both matrices, the carbonate and the oxide fractions accounted for over 90% of the zinc present in the soil. The organic fraction constituted over 70% of the copper in the soil and sediments. Sequential extraction of the soil and sediments after washing with the various surfactants indicated that the biosurfactants, rhamnolipid or surfactin with NaOH, could remove the organically-bound copper and that the sophorolipid with acid could remove the carbonate and oxide bound zinc and cadmium.
Concerning the mechanism for metal removal by the surfactants, the techniques of octanol-water partitioning, ultrafiltration and zeta potential measurements indicated that the surfactants removed the metals first by sorption at the soil interphase, followed by desorption of the metal through interfacial tension lowering and fluid forces and then solubilization of the metal within the micelle.
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Baraka, Ahmad. "Removal of heavy metals from aqueous solutions by novel melamine-formaldehyde-polyaminopolycarboxylic acid chelating adsorbents." Thesis, University of Strathclyde, 2006. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21660.
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The contamination of water recourses by heavy metals is a serious worldwide environmental problem. Industrial activities, mining and coal combustion are typical contamination sources. Removal of these metals from wastewater effluents is crucial as this contamination is non-biodegradable and highly toxic. Extensive research has been carried out to introduce new materials which alleviate these metals from wastewater effluents before their discharge into water bodies such as rivers and lakes. Conventional methods to remove heavy metals from wastewater include chemical precipitation, ion-exchange and chelation-adsorption. Adsorption is an important and developing research area because of the new material types available according to the application. Furthermore, it is standard process to place the adsorbent in a column and pump the wastewater through in a continuous system. It is also a cost-effective process. Chelating adsorbents are typically characterised by functional groups containing 0, N, S, and P donor atoms which coordinate to different heavy metal ions. It is necessary that the adsorbent has a high capacity and that the kinetics of adsorption is sufficiently fast. Polyaminepolycarboxylic (PAPC) acids are strong chelating agents and form stable chelates with different types of metals: transition, lanthanides and actinides. In spite of its exceptional chelating power, many of the PAPC compounds - such as DTPA (8-coordinations), CDTA (6-coordinations) and NTA (4-coordinations) - have not been thoroughly studied for use as active sites in adsorbent materials for heavy metal remediation from contaminated water effluents. Furthermore, the effect of the number of coordination groups on the adsorption behaviour has not been investigated. Use of these strong chelating agents (PAPC) for heavy metal removal by a polymeric adsorbent is presented in this study, with discussion of the chelation mechanism and affinity. The PAPC chelating agents were anchored on melamineformaldehyde (MF) gel. Although MF gel has suitable chemical and physical properties allowing the production of an adsorbent for heavy metal removal, it has not been studied. MF gel is porous and its matrix has a suitable platform to functionalize with some chelating compounds. PAPC-modified melamine-formaldehyde matrix is easy to produce compared to conventional chelating resins based on styrene/divinylbenzene. In this work, melamine-formaldehyde-polyaminepolycarboxylic acid (MF-PAPC) chelating adsorbents were synthesised by anchoring polyaminepolycarboxylic acids (PAPC) to melamine by the reaction of the carboxylic group of PAPC with a primary amine group of melamine forming a covalent amide bond during MF matrix formation. A series of samples of these adsorbents were prepared by varying water content, acidity of water and temperature as parameters to control the properties of the product. Samples of MF-DTPA, MF-NTA and MF-CDTA were chemically characterized using IR, elemental analysis, TPD-MS, 13C-NMR and 15N-NMR. Physical characterisation was carried out using BET, FE-SEM, and XRD techniques. Elemental analysis and BET results were used to select optimum samples for adsorption experiments. Selected MF-PAPC adsorbent samples are hydrophilic, amorphous and rigid. The content of PAPC in the dry adsorbent samples ranges from 1.08 to 2.28 mmole g⁻¹. The MF-PAPC adsorbents have reasonable surface areas (ranges from 159 to 179 m² g⁻¹) and a mesoporous structure (average pore diameter: 19 - 130 Å). The adsorption performance of MF-PAPC adsorbents was investigated against environmentally problematic divalent metal ions, namely, Cu(II), Co(II), Cd(II) and Zn(II). The adsorption behaviour of these adsorbents was characterised using mixture solutions of these four ions. The effects of different controlling parameters (solution initial pH, temperature, metal ions initial concentration and contact time) on adsorption were considered. Experimental data was fitted to the selected kinetic and isotherm models to suggest the best models to represent the adsorption process on MF-PAPC adsorbents. The thermodynamic parameters (adsorption free energy, enthalpy and entropy) were also calculated and a mechanism of adsorption is suggested according to the evaluation of the results. It was found that MF-PAPC adsorbents follow reversible first order and pseudo second order models to represent the adsorption kinetics. The Langmuir isotherm model gives the best representation of the adsorption processes. These findings indicate the chemical and reversible nature of the adsorption process. Thermodynamically, the adsorption was found to be spontaneous and exothermic. The entropy change shows that adsorption is not favourable. The results indicate that chelation and ion exchange are the mechanisms of adsorption with chelation the dominant type especially at lower temperatures and higher initial pH values. The PAPC type controls the affinity order of the four heavy metals. MF-PAPC adsorbents are distinguished by chelation-adsorption. The adsorption can be universal, or selective according to the PAPC type. Moreover, the selectivity order is different and depends on the PAPC type. MF-PAPC adsorbents can be used for metal-separation applications due to the higher affinity towards transition elements, lanthanides and actinides with respect to alkali and alkaline earth metals. The elution of the adsorbed metal ions was successfully accomplished using a solution of EDTA due to its high chelation power. The MF-DTPA adsorbent was used in a packed column for removal of the Cu(II) ion in a continuous up-flow system. The parameters of the study were: Bed height, flow rate and initial concentration. The Thomas model was used to fit the kinetic data. The BDST model was used to examine the possibility of scaling-up the laboratory set-up to industrial scale. The capacity of dsorption was found to be sensitive to bed height (positive: due to mass transfer), initial concentration (positive: due to concentration driving force) and flow rate (negative: due to contact time). It was found that the adsorption zone moves up the column at a constant speed for different bed heights. Hence, the process can be scaled-up for practical use using a BDST model.
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Jackson, Ricardo Rodriguez Silva [Verfasser]. "Electrocoagulation Removal of Heavy Metals from Industrial Wastewater in Continuous Flow / Rodriguez Silva Jackson Ricardo." Aachen : Shaker, 2019. http://d-nb.info/1188550721/34.
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Robertsson, Jonas, and Camilla Andersson. "Characterisation and removal of heavy metals in tannery effluents through the use of local materials." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-239005.
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Chromium and other heavy metals are known to cause issues related to human and environmental health when they occur in high concentrations in ecosystems. Chromium poses a particularly large threat if it occurs in its hexavalent form, Cr(VI), as it is highly reactive and carcinogenic. The aim of this project was to investigate the wastewater emitted from a tannery in Liwonde, Malawi, with respect to the metals Cr, Al, Cd, Cu, Fe, Mn, Pb and Zn, and to reduce the concentrations using locally available materials. A particular emphasis was put on chromium. Wastewater collected from the tannery was analysed to determine the total and dissolved concentrations of the metals using a Microwave Plasma-Atomic Emission Spectrometer (MP-AES). The wastewater was then mixed with various dosages of peeled and unpeeled Moringa Oleifera seed powder as well as pure Moringa Oleifera shell powder and sand collected from river Shire. Thereafter, the remaining concentrations of metals were analysed. Additional analyses of various contact times were performed for the removal agent that had shown the best results. The analyses showed a total chromium concentration of 2.25 ppm and a dissolved chromium concentration of 0.251 ppm in the wastewater discharged from the tannery. Both concentrations were lower than what had initially been expected but still above both the WHO guideline value for chromium in drinking water and the Swedish threshold value for chromium in industrial wastewater (0.05 ppm). No other metals were found in concentrations above trace levels. All of the investigated removal agents, except for pure shell powder, showed positive results for chromium removal. The highest removal observed for dissolved chromium was 72 % and occurred with a removal agent mixture of 5.0 g of river sand and 2.0 g of unpeeled Moringa Oleifera seed powder to 100 mL of wastewater. The reduction of total chromium was 97 % for the same removal agent mixture. However, lower dosages of the removal agents also gave a chromium removal of similar size. Due to resource limitations, no analysis of whether the wastewater contained Cr(III) and Cr(VI) could be performed. Considering the low initial concentrations of metals emitted from the tannery, there is no urgent need for further treatment of the wastewater. This study has however substantiated the theory that Moringa Oleifera seeds can be used as a low-cost chromium remediation agent in wastewater, a result that can be of use to improve the water quality in other industries and applications.Det har länge varit känt att krom och andra tungmetaller kan orsaka hälso- och miljöproblem när de förekommer i höga koncentrationer i ekosystem. Krom utgör ett särskilt stort hot om det förekommer i sin sexvärda form, Cr(VI), eftersom det är mycket reaktivt och cancerogent. Syftet med detta projekt var att undersöka avloppsvattnet från ett garveri i Liwonde, Malawi, med avseende på metallerna Cr, Al, Cd, Cu, Fe, Mn, Pb och Zn, samt att minska koncentrationerna med hjälp av lokalt tillgängliga material. En särskilt tonvikt lades på krom. Avloppsvatten som inhämtats från garveriet analyserades med hjälp av en mikrovågsplasma-atomemissionsspektrometer (MP-AES) för bestämning av total samt löst koncentration av metallerna. Avloppsvattnet blandades sedan med olika doser av pulver från skalade och oskalade Moringa Oleifera-frön, liksom med pulver från skal av Moringa Oleifera-frön och sand från Shire-floden. Därefter analyserades proverna med avseende på återstående metallkoncentrationer. Ytterligare undersökningar genomfördes med olika kontakttider för det inbindningsmedel som visat bäst resultat. Analyserna visade en total kromkoncentration på 2,25 ppm och en löst kromkoncentration på 0,251 ppm i det avloppsvatten som släpptes ut från garveriet. Båda koncentrationerna var lägre än vad som ursprungligen hade förväntats, men ändå över både WHOs riktlinjer för krom i dricksvatten och det svenska gränsvärdet för krom i industriellt avloppsvatten (0,05 ppm). Inga andra metaller påvisades i betydande koncentrationer. Alla undersökta inbindningsmedel, med undantag av Moringa Oleifera-skal, visade positiva resultat för kromrening. Den största observerade reningen för löst krom var 72 %, och uppmättes för en blandning av 5,0 g sand och 2,0 g pulver av oskalade Moringa Oleifera-frön till 100 mL avloppsvatten. Reduktionen av totalt krom var 97 % för samma blandning. Även lägre doser gav dock en nästan lika hög reningsgrad. På grund av resursbegränsningar kunde ingen analys av huruvida avloppsvattnet innehöll Cr(III) eller Cr(VI) genomföras. Då avloppsvattnet från garveriet endast innehöll låga koncentrationer av metaller finns inget akut behov av ytterligare rening. Denna studie har dock styrkt tesen att Moringa Oleifera-frön kan användas som ett lågkostnadsalternativ för rening av krom i avloppsvatten. Detta resultat kan vara användbart för att förbättra vattenkvaliteten vid andra industrier och tillämpningar.
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Brown, Pauline Anne. "The application of peat and lignite to the removal of heavy metals from industrial wastewater." Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360482.
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Dahrazma, Behnaz. "Removal of heavy metals from sediment using rhamnolipid." Thesis, 2005. http://spectrum.library.concordia.ca/8462/1/NR09963.pdf.
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The interaction of heavy metals with sediments is complex and means are required to understand this matter more fully. Soil washing is among the methods available to remove heavy metals from sediments. This research was devoted to evaluating the performance of rhamnolipid for the removal of heavy metals, copper, zinc, and nickel, in batch and continuous flow configurations under different conditions, to investigate the mobility and availability of heavy metals by means of selective sequential extraction, and to find the mechanism for removal of heavy metals from the contaminated sediment obtained from the Lachine Canal, Quebec by using a rhamnolipid. The removal of heavy metals from sediments was up to 37% for Cu which was mostly from the organic, 13% of Zn which was mostly from the carbonate, and 27% of Ni which was mostly from oxide and carbonate fractions when rhamnolipid without additives was applied in the continuous flow configuration. By ion exchange experiments, complexation was found to be the major mechanism of removal for all three metals by rhamnolipid. Adding 1% NaOH elevated the role of ion exchange mechanism up to 67.1% for removal of zinc from the sediment. Rhamnolipid adsorbed to the sediment according to the Freundlich isotherm. The zeta potential of the sediment was measured at -24.3 mV for distilled water, -9.5mV for 2%, and -29.5 mV for 0.5% rhamnolipid. Scanning electron microscopy showed that washing with rhamnolipid does not change the texture of the sediment. Augmentation of the wetted surface area of the sediment improved the removal for all three metals (up to 3.5 times for copper), which emphasizes the role of this parameter in the removal process. A theory was established to explain the removal process of the metals, including wetting, contact of rhamnolipid to the surface of the sediment and detachment of the metals from the sediment. Rhamnolipid has proven its ability as a washing agent in heavy metals removal from sediments, but more research is required to improve the performance of the rhamnolipid before scale-up.
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LI, DING-HUA, and 李定華. "Removal of heavy metals by potassium ferrate (VI)." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/3wg86z.
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碩士東海大學
化學工程與材料工程學系
105
Potassium ferrate (VI) is widely applied recently. It can used to disinfect potable water, resolve waste water which contains organic compounds, and deal with sewage. Potassium ferrate (VI) is not a harmful substance for water treatment. It will be reduced to Fe(OH)3 when it reacts during water treatment progress. Fe(OH)3 has good flocculation which leads it to absorb suspension, heavy metals, and multiple organic compounds in water. In addition, potassium ferrate (VI) reacts with heavy metal solutions to form insoluble compounds such as M(HFeO4)2 or M(FeO4) to reduce the concentration of heavy metals in water. Above all, the by-product form in the process of water treatment is harmless to the human body and environment. For this reason, potassium ferrate (VI) is recognized as a green disinfectant. In this study, hypochlorite oxidation method is used to prepare potassium ferrate (VI). Its advantages are short reaction time, low reaction temperature, production on large scale, readily available equipment, and high purity. The yield and purity of prepared K2FeO4 are in the ranges of 35-93% and 35-87%, respectively. Ni2+, Co2+, and Cu2+ are removed by synthesized potassium ferrate (VI). The UV/Vis absorption wavelength of Ni2+, Co2+, and Cu2+ are 394, 510, and 800 nm, respectively. Heavy metal solutions of different compositions are prepared and heavy metals are removed by adding potassium ferrate (VI). Heavy metal absorbances are measured by UV/Vis and removal efficiencies of heavy metals are calculated.
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Chen, Shen-Yi, and 陳勝一. "Removal of Heavy Metals from Contaminated Sediment by Bioleaching." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/90818207037802146175.
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博士國立交通大學
環境工程所
87
The management of contaminated sediments in the aquatic environment is one of the most important environmental issues. In future, the remediation of a contaminated river will be faced with two typical problems-- increasing volumes of dredged materials and high concentrations of toxic substances. The objective of this dissertation is to develop a technique for treatment of the large quantity of metal contaminated sediments in the remediation of contaminated rivers. A bacterial mediated leaching process with a mixed culture of two sulfur-oxidizing bacteria for removal of heavy metals form contaminated sediments was established in this dissertation. The effects of operational parameters on solubilization of metals from sediments were assessed. It was found that continuous growth of two species of thiobacilli resulted in sediment acidification and metal solubilization. Because of higher buffer capacity of sediment, the rate of decline in pH decreased with increasing solids concentration of sediment. The rates of sulfate production of bacteria increased as sediment solids concentrations increased. In the heavy metals of concern, the maximum leaching efficiencies of Pb, Ni and Cr were apparently influenced by sediment solids concentrations. The metal solubilization from sediments appeared to follow a first order reaction related with the sediment solids concentration. In the bioleaching process, elemental sulfur is usually used as the substrate for bacterial growth. Adsorption of bacteria to sulfur particles is the first step for oxidaion of sulfur. The more the concentrations of elemental sulfur, the faster the rates of acid production and metal solubilization. But sulfur concentrations in excess of 5% (w/v) were found to be inhibitory to bacterial activity and metal solubilization in the bioleaching process. The optimum concentration of sulfur fed in the bioleaching process is recognized to be 5% (w/v). A first-order reaction related to sulfur concentration is also used to describe the metal solubilization in this bioleaching process when the sulfur concentration are below 5% (w/v). To prevent the reacidification of treated sediments and to recover the remaining sulfur, the sulfur particles in the form of pastilles and pellets are used as the energy source for thiobacilli in the bioleaching process for replacing sulfur powder. The maximum adsorption obtained from the Langmuir isotherm capacity is applied to calculate the specific surface area of sulfur particle. These results of specific surface areas are significant to interpret the sediment acidification and metal solubilization. The pH reduction and metal solubilization are significantly enhanced while reusing of the recovered sulfur particles. It is very possible to reuse the recovered sulfur particles in the bioleaching, sulfur pastilles especially. Finally, a modified logistic model was successfully developed to estimate the variations of pH in the bioleaching process. Besides, the solubilization of heavy metals from sediments is highly pH-dependent and a non-linear efficiency equation of metal solubilization related to pH value in the bioleaching process was established. Therefore, a more simple and faster method of measuring pH is able to simulating the metal solubilization in the bioleaching process.
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Shen, Hxu-Sheng, and 沈旭昇. "Removal of Heavy Metals from Waste Water by Fungi." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/44068167299961690732.
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Chung, Cheng-Chen, and 張丞笉. "Removal of heavy metals using biosorbents from aqueous solution." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/66481785636526588469.
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碩士中原大學
土木工程研究所
99
The methods of treating effluent contained heavy metals traditionally include precipitation, ion exchange, adsorption, membrane processing and electro dialysis. Ion exchange is the most common method for removal of the low concentration heavy metals in the effluent. However, resin possesses high production costs. A number of researchers, therefore, have dedicated to develop biosorbents with the low-costs, high adsorption capacity and environmental affinity to remove the harmful heavy metals in recent years. The primary purpose of study is to select fibrous materials, such as citrus maxima, passion fruit shell and sugarcane bagasse, to produce the biosorbents with bio-rich COOH functional groups using simple chemical processing. The obtained biosorbents are used to absorb the heavy metals of Cu2+、 Cd2+、 Ni2+、 Pb2+ by column in accordance with difference between the pH values and flow rates. The results indicate the biosorbents from the citrus maxima and passion fruit shell possess high adsorption capacities. FTIR spectra can exhibit the adsorbent surface which is equipped with functional groups of carboxyl and hydroxyl. The functional groups provide nonbonding electron pair bonding to heavy metals with achieving the adsorption results. The test of cation exchange capacity demonstrates the surfaces of adsorbents possess negative charge that can absorb heavy metal ions by the ion exchange. The study indicates that citrus maxima and passion fruit shell produce the highest adsorption capacities at pH = 5, whereas sugarcane bagasse is at pH = 6. For the adsorption equilibrium and dynamic column experiments, adsorption capacities for all heavy metals are the following order: citrus maxima > passion fruit shell > sugarcane bagasse. The adsorption capacities for heavy metal are: Pb> Cd> Cu> Ni.