Dissertations / Theses on the topic 'Nanoscale iron'
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Welch, Regan Eileen. "Reduction of 2,4,6-Trinitrotoluene with Nanoscale Zero-Valent Iron." Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1180914214.
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Echols, Erica. "Environmental remediation of TNT using nanoscale zero-valent iron metal." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0003105.
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Church, Nathan Stewart. "Magnetic properties of iron-titanium oxides and their nanoscale intergrowths." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609524.
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Ghahghaei, Nezamabadi Shirin. "Accelerated Degradation of Chlorinated Solvents by Nanoscale Zero-Valent Iron Coated with Iron Monosulfide and Stabilized with Carboxymethyl Cellulose." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1452681950.
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Solórzano, Rodríguez Rubén. "Iron-catechol based nanoscale coordination polymers as efficient carriers in HIV/AIDS therapy." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/669503.
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En aquesta tesi, es presenten metodologies sintètiques per a la preparació de compostos catecólics conjugats a fàrmacs antiretrovirals mitjançant un enllaç sensible a enzims. Com a prova de concepte, el fàrmac anti-VIH zidovudina s’utiliza como a punt de partida. Utilitzant aquest conjugat zidovudina-catecol es preparen polímers de coordinació nanostructurats (NCPs) basats en ferro. Després d’una optimització de la metodologia sintètica per aconseguir una mida de partícula i una dispersió col·loídal adequada, s’avalua el perfil d’alliberament de zidovudina en NCPs en presencia o absència d’esterases. Per útim, es realitza una avaluació biològica d’aquests NCPs que inclou citotoxicitat, internalització cel·lular i assajos d’activitat anti-VIH en limfòcits infectats. A continuació, s’explora la síntesi de nous conjugats de catecol amb fàrmacs antiretrovirals. Específicament, conjugats d’emtricitabina i raltegravir s’utilitzan per formar NCPs contenint només un fàrmac en la seva estructura. Després de la seva caracterizació i determinació del perfil d’alliberament en cada cas, se sintetitzen NCPs contenint una barreja d’ambdós fàrmacs i el seu comportament en quant a alliberament es compara amb el casos anteriors. Per acabar, s’exploren metodologies per a la síntesi de nous conjugats de catecol utilitzant els fàrmacs lamivudina i tenofovir.En esta tesis, se presentan metodologías sintéticas para la preparación de compuestos catecólicos conjugados a fármacos antiretrovirales mediante un enlace sensible a enzimas. Como prueba de concepto, el fármaco anti-VIH zidovudina se usa como punto de partida. Utilizando este conjugado zidovudina-catecol se preparan polímeros de coordinación nanostructurados (NCPs) basados en hierro. Después de optimizar la metodología sintética para lograr un tama\u00F1o de partícula y una dispersión coloidal adecuadas, se evalúa el perfil de liberación de zidovudina en los NCPs en presencia y ausencia de esterasas. Por último, se realiza una evaluación biológica de estos NCPs que incluye citotoxicidad, internalización celular y ensayos de actividad anti-VIH en linfocitos infectados. A continuación, se explora la síntesis de nuevos conjugados de catecol con fármacos antiretrovirales. Específicamente, conjugados de emtricitabina y raltegravir se utilizan para formar NCPs conteniendo un solo fármaco en su estructura. Después de su caracterización y determinación del perfil de liberación para cada caso, se sintetizan NCPs conteniendo una mezcla de ambos fármacos y su comportamiento en cuanto a liberación se compara con los casos anteriores. Para acabar, se exploran metodologías para la síntesis de nuevos conjugados de catecol utilizando los fármacos lamivudina y tenofovir.
In this thesis, synthetic methodologies for the preparation of catechol compounds conjugated to antiretroviral drugs through an enzyme-sensitive bond are presented. As a proof-of-concept, the anti-HIV drug zidovudine is used as a starting point. Iron-based nanoscale coordination polymers (NCPs) are then prepared using this zidovudine-catechol conjugate and a bis(imidazole) bridging ligand. After optimization of the synthetic methodology to achieve a suitable particle size and colloidal dispersion, the drug release profile of the NCPs in the presence or absence of esterases is determined by HPLC. Then, a biological evaluation of the nanoparticles is performed, including cytotoxicity, cellular uptake and anti-HIV activity in infected lymphocytes.As a step forward, the synthesis of additional catechol compounds attached to anti-HIV drugs is explored. Functionalization of emtricitabine and raltegravir with catechol allows the formation of analogous NCPs for each drug. After the determination of their drug release profile by methodologies developed in HPLC, NCPs containing a mixture of both drugs are prepared and their release behavior is compared to the individual NCPs. Last, methodologies for the preparation of other catechol conjugates with lamivudine and tenofovir are explored for their application in NCPs synthesis.
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Kajenthira, Arani. "Mercury immobilisation in situ : Interactions between charcoal, nanoscale iron, and sulphate-reducing bacteria." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533855.
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Huang, Dennis. "Nanoscale Investigations of High-Temperature Superconductivity in a Single Atomic Layer of Iron Selenide." Thesis, Harvard University, 2016. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493535.
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The potential of interface engineering to enhance electronic properties is exemplified in a single atomic layer of FeSe grown on SrTiO$_3$, which exhibits an order-of-magnitude increase in its superconducting transition temperature ($T_c$ up to 110 K) compared to bulk ($T_c$ = 8 K). Since this discovery in 2012, efforts to reproduce, understand, and extend this finding continue to draw both excitement and scrutiny. In this thesis, we report the use of a combined molecular beam epitaxy (MBE) and scanning tunneling microscopy (STM) system to grow and image films of superconducting FeSe/SrTiO$_3$. In particular, we investigate and harness atomic defects in as-grown films to derive microscopic insights in two directions. First, we image quasiparticle interference (QPI) patterns generated around defects in order to reconstruct the electronic structure of the unperturbed system, and uncover pieces of the puzzle of high-$T_c$ superconductivity in a monolayer of FeSe. Second, we characterize the atomic structure of defects using density functional theory (DFT), with possible implications on film quality and nanostructuring.Physics
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Dislaki, Evangelia. "From macro- to nanoscale electrodeposited iron-copper (Fe–Cu) for energy-efficient and sustainable applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/665449.
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Aquest treball se centra en l'electrodeposició i l'estudi del sistema Fe-Cu, tant sobre substrats llisos per a l’obtenció de pel·lícules continues com en substrats proveïts amb un reticle o màscara, així com la fabricació i caracterització de motius de mida submicromètrica, nanobarres, microbarres i tubs, destinats a ésser utilitzats en una gran varietat d’aplicacions mediambientals i d’eficiència energètica.
En primer lloc, s’han dissenyat diferents electròlits per al dipòsit electroquímic de recobriments FexCu1-x de diversos micròmetres de gruix en un ampli rang de composició (0≤x≤86). S’ha investigat l'efecte de diversos agents complexants i condicions d’electrodeposició com el pH, la temperatura i l'agitació magnètica del bany sobre la morfologia, estructura, composició elemental i comportament magnètic dels dipòsits obtinguts. S’ha vist que el Fe i el Cu es troben parcialment aliats, malgrat la baixa solubilitat mútua entre ells, i que la magnetització de saturació es pot modular fàcilment a través del contingut de Fe.
A continuació, s’han extrapolat els protocols sintètics establerts per al creixement dels recobriments continus a la fabricació de pel·lícules primes amb una porositat jeràrquica aconseguida mitjançant electrodeposició sobre substrats decorats amb cristalls col·loïdals (colloidal crystal templating). S’ha avaluat la humectabilitat d'aquestes pel·lícules i la seva habilitat per extreure l’oli en mescles i emulsions aigua-oli. S’ha vist que l'elevada relació superfície-volum de les pel·lícules, juntament amb l'elevada rugositat derivada de la seva estructura macroporosa i el relleu nanomètric al llarg de les parets de porus, genera un marcat caràcter hidrofòbic / oleofílic dels dipòsits i una notòria capacitat d'absorció d’oli. A diferències de les capes contínues, que són més gruixudes, el grau d’aliatge entre el Fe i el Cu és total en les pel·lícules primes macroporoses de Fe75Cu25 i Fe85Cu15.
A més, s’ha demostrat que l'elevada relació superfície-volum i la nanoporositat inherent de les estretes parets de porus de les pel·lícules macroporoses les han convertit en excel·lents candidates per al control de la magnetització mitjançant voltatge. De fet, s'aconsegueix una reducció de la coercitivitat fins a un 25% en ser polaritzades negativament. Aquesta és una metodologia prometedora per reduir el consum d'energia, ja que la inversió de magnetització s’aconsegueix aplicant camps magnètics més baixos (és a dir, els corrents elèctrics involucrats són més baixos i, per tant, la dissipació de potència per efecte Joule es minimitza).
A continuació, tenint en compte la tendència actual cap a la miniaturització, s’han crescut estructures submicromètriques de tres geometries i mides diferents mitjançant electrodeposició sobre substrats prelitografiats. Aquests substrats es van preparar per litografia per feixos d'electrons per tal d’assegurar una elevada resolució dels motius. Tot i que la literatura existent sobre motius submicromètrics litografiats es basa principalment en estructures amb una alçada inferior a 50 nm, les estructures que s’han preparat en aquesta Tesi fan aproximadament 200-300 nm d'alçada en funció de les condicions d’electrodeposició. Això dóna lloc a fenòmens interessants com ara un gradient de composició i, per tant, diferents propietats estructurals al llarg del gruix. S’han investigat les propietats magnètiques mitjançant microscòpia de forces magnètiques, indicant l’existència d’efectes tipus magnetic curling.
Finalment, s’han fabricat nano i microbarres i tubs de diferent diàmetre magnètics i amb gradient de composició en membranes de policarbonat a través de mètodes d'electrodeposició convencionals i també a partir de banys amb surfactants amfifílics (micelle-assisted electrodeposition). El caràcter ferromagnètic de les estructures obtingudes ha permès la seva manipulació magnètica remota, mentre que s’ha confirmat la propulsió direccional fotocatalítica dels microtubs.This work is focused on the electrodeposition and study of Fe-Cu in the form of continuous and patterned thin films and coatings as well as the fabrication and characterization of submicron motifs, nano- and microrods and tubes targeted at a variety of environmental and energy-efficient applications. Firstly, different electrolytes are developed for the electrochemical deposition of FexCu1−x coatings of several micrometers in thickness over a wide composition range (0≤x≤86). The effect of various complexing agents and plating conditions such as pH, temperature and magnetic stirring on the morphology, structure, elemental composition and magnetic behavior is investigated. It is shown that the coatings are partially alloyed, despite the low mutual solubility of Fe and Cu, and saturation magnetization can be easily tuned by an adjustment of the Fe content. Next, the synthetic protocols for the continuous coatings are extrapolated to the fabrication of patterned thin films with a hierarchical porosity achieved by coupling electrodeposition with colloidal lithography. The wetting properties of these films and their potential towards water-oil separation in mixtures and emulsions is assessed as a proof of concept. The high surface-to-volume ratio of the films in conjunction with the high roughness achieved by the macroporous network and the nanosized features along the pore walls lead to a strong hydrophobic/oleophilic nature of the deposits and an impressive absorption capacity. Notably, contrary to the thick coatings, the continuous and patterned Fe75Cu25 and Fe85Cu15 thin films are demonstrated to be fully alloyed. Furthermore, the high surface-to-volume ratio and the inherent nanoporosity of the narrow pore walls of the patterned films unveil their excellent potential towards voltage control of magnetization. Indeed, a coercivity reduction of up to 25% under application of a negative bias is achieved. This constitutes a promising way to curtail power consumption since magnetization reversal can then occur with lower applied magnetic fields (i.e., lower electric currents and minimized Joule heating power dissipation). Next, given the current trend towards miniaturization, submicron structures of three geometries and sizes are produced through electrodeposition onto pre-lithographed substrates. These substrates were previously prepared using electron-beam lithography which ensured a high feature quality. While existing literature on lithographed submicron motifs is largely based on structures below 50 nm in height, the structures prepared here are approximately 200-300 nm in height depending on plating conditions. This gives rise to interesting phenomena such as a compositional gradient, and thus different structural properties along the thickness. The magnetic properties are also thoroughly investigated with magnetic force microscopy suggesting magnetic curling effects. Finally, compositionally graded magnetic nano- and microrods and tubes of various diameters are fabricated in polycarbonate track-etched membranes through conventional as well as micelle-assisted electrodeposition methods. The ferromagnetic character of the material enables wireless magnetic steering while photocatalytically-driven directional propulsion of the microtubes is also confirmed.
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Chowdhury, Md Abu Raihan. "Removal of Select Chlorinated Hydrocarbons by Nanoscale Zero-valent Iron Supported on Powdered Activated Charcoal." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1496150130687849.
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Li, Jing. "Multi-scale investigations of carboxymethyl cellulose- coated nanoscale zero valent iron particle transport in porous media." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123130.
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Subsurface injection of nano scale zero valent iron (NZVI) particles is an emerging technology for in situ remediation of the sites contaminated by toxic contaminants such as chlorinated organic dense non aqueous phase liquids (DNAPLs) and heavy metals. One of the key challenges in applying NZVI particles for remediation at the field scale is that NZVI particles are not readily transported in subsurface porous media. The overall objective of this research is to address this challenge by conducting a number of column experiments and 2-D pilot scale tank experiments as well as by exploring the deposition mechanics of metal nanoparticles theoretically. Although numerous studies have focused the stability and transport of polymer/polyelectrolyte coated NZVI particles, the comparison of the effect of the same type of polyelectrolyte stabilizer with different molecular weight on the stability and transport of the corresponding coated NZVI particles has not been systematically conducted to date. Varying molecular weights of homologous polyelectrolytes can cause changes in viscosity and rheology in free solution, and alter the extent of colloidal stability when coated on the nanoparticles. Furthermore, most of the studies on NZVI particle transport have been conducted in the vertically placed columns, which are not representative with the actual flow orientation in field, leading to a potential difference of transport performance of NZVI particles between the commonly used vertical flow orientation and the horizontal flow model. In addition, the scale-up effects (from laboratory-scale column to pilot-scale or field-scale demonstrations) on NZVI transport are reported. In this study, a thorough investigation on NZVI transport is conducted in a 2-D pilot-scale tank to shed some light on the transport performance of NZVI particles under conditions that are more close to actual circumstances. Finally, to calculate the deposition rate coefficient of metal nanoparticles during transport, a considerable number of studies on NZVI particles transport employed equations for predicting the single collector contact efficiency that are developed on the basis of the numerical calculations for common colloidal particles such as latex particles, which have smaller densities than those of metal particles. Taking the horizontal flow mode and the density effects for metal nanoparticles into consideration, a new methodology is developed in three dimensions (3-D) to more precisely predict the single collector efficiency of NZVI particles.In the first study, the influence of the molecular weight of the polyelectrolyte grafted on NZVI particle on its stability and transport was investigated. Three carboxymethyl celluloses (CMC) with different molecular weights (90,000 Da, 250,000 Da and 700,000 Da) were used to stabilize NZVI particles. The comparison of the results revealed that the stability and transport of NZVI particles were improved significantly by CMC with high molecular weight, due to its high viscosity property. In the second study, the effects of gravity on NZVI particle during its transport were extensively assessed in vertical and horizontal placed columns under different conditions (mean sand diameters and NZVI concentrations). The results indicated that the gravity forces significantly reduced NZVI particles transport in coarse sand and at high NZVI concentration in horizontally placed columns. To thoroughly study the impact of horizontal orientation flow on the transport of NZVI particles at a larger scale, a series of transport experiments were conducted in a pilot-scale 2-D tank. Furthermore, to address the challenges met in predicting the single collector efficiency in horizontal orientation flow mode, a methodology based on trajectory analysis of particles around a Happel sphere-in-cell model for porous media in 3-D was developed.L'injection souterraine des nanoparticules de fer à zéro valence (NZVI) est une technologie émergente pour l'assainissement in situ des sites contaminés par des polluants toxiques comme les solvants chlorés et les métaux lourds. L'un des principaux défis dans l'application des particules de NZVI à des fins de rémédiation est que les particules de NZVI ne sont pas facilement transportées dans des milieux poreux souterrains. L'objectif général de cette recherche est de relever ce défi en réalisant un certain nombre d'expériences en colonnes et en 2-D sur desbassins à l'échelle pilote ainsi que par l'analyse de la mécanique de dépôt de nanoparticules métalliques en théorie. Bien que de nombreuses études ont porté sur la stabilité et le transport de nanoparticules de fer (NZVI) revêtues de polymère / poly-électrolyte, la comparaison de l'effet du même type de stabilisant en polyélectrolyte ayant des poids moléculaires différents, sur la stabilité et le transport des particules de NZVI enrobées n'ont pas été effectués systématiquement à ce jour. Des poids moléculaires variables des polyélectrolytes homologues peuvent provoquer des variations de viscosité en solution libre et dans l'étendue de la stabilisation colloïdale électrostérique de NZVI en s'attachant sur la surface des nanoparticules. Des études antérieures sur le transport des particules NZVI ont été menées dans les colonnes placées verticalement, qui souvent ne sont pas représentatifs de l'orientation de l'écoulement réel sur le champ, ce qui conduit à une différence de potentiel de performance du transport de particules NZVI entre l'orientation de l'écoulement vertical couramment utilisé et le modèle à flux horizontal. Outre, les effets à l'échelle grandissante (de la colonne à l'échelle de laboratoire, pilote ou des manifestations à l'échelle du champ) sur le transport de NZVI sont rapportés. Dans cette étude, une enquête approfondie sur le transport de NZVI est effectuée dans un réservoir en 2-D à l'échelle pilote afin de faire la lumière sur la performance du transport des particules de NZVI dans des conditions qui sont plus près de la situation réelle. Enfin, pour calculer le coefficient de vitesse de dépôt des nanoparticules de métal en cours de transport, un nombre considérable d'études sur les particules de NZVI ont été effectué en employant des équations de transport à fin de prédire le contact de rendement du capteur unique qui sont mis au point sur la base des calculs numériques pour les particules colloïdales communes moins denses tels que des particules de latex, qui ont des densités plus inferieures que celles des particules de métal. Prenant le mode d'écoulement horizontal et les effets de la densité de nanoparticules métalliques en considération, une nouvelle méthode est développée en trois dimensions (3-D) afin de prédire plus précisément l'efficacité du collecteur unique de particules NZVI .
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Taguchi, Taketo. "A molecular approach to nanoscale magnetic materials new iron and manganese clusters from the use of pyridyl alcohols /." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0041194.
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Franze, Andrew. "Accelerated Degradation of Chlorinated Solvents by Copper-Modified Nanoscale Zero Valent Iron (Cu-nZVI) Stabilized with Carboxymethyl Cellulose." Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1432828633.
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Moura, Cinthia Cristine de. "Green stabilization of nanoscale zero-valent iron (nZVI) with rhamnolipids produced by agro-industrial waste : application on nitrate reduction /." Rio Claro, 2019. http://hdl.handle.net/11449/190850.
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Orientador: Jonas ContieroResumo: A contaminação ambiental causada por compostos orgânicos é um importante problema que afeta solos e água superficiais. Para reduzir ou remover esses poluentes, os locais contaminados são geralmente tratados com métodos físicos e químicos. No entanto, a maioria dessas técnicas de remediação é custosa e geralmente leva à remoção incompleta e à produção de resíduos secundários. A nanotecnologia consiste na produção e aplicação de estruturas extremamente pequenas, cujas dimensões estão na faixa de 1 a 100 nm, neste cenário a nanopartícula de ferro zero valente representa uma nova geração de tecnologias de remediação ambiental. É não tóxica, abundante, barata, fácil de produzir, e seu processo de produção é simples. No entanto, a fim de diminuir a tendência de agregação, a nanopartícula de ferro zero é frequentemente revestida com surfactantes. A maioria dos surfactantes é quimicamente sintetizado a partir de fontes petroquímicas, eles são persistentes ou parcialmente biodegradáveis, enquanto oferecem baixos riscos à saúde humana, esses compostos podem prejudicar plantas e animais. Para diminuir o uso de métodos químicos, a síntese e estabilização verde de nanomateriais metálicos apresentam-se como uma opção menos perigosa ao meio ambiente. Os biossurfactantes podem potencialmente substituir qualquer surfactante sintético, eles são compostos extracelulares produzidos por microrganismos, como bactérias, e cultivados em diferentes fontes de carbono, podendo ser substratoshidrofílico... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Environmental contamination caused by organic compounds is the most important challenge that affects a huge number of soils and water surfaces. To reduce or remove these pollutants, contaminated sites are usually treated using physical and chemical methods. However, most of these remediation techniques are expensive and commonly lead to incomplete removal and to the production of secondary wastes. Nanotechnology is the production and application of extremely small structures, whose dimensions are in the range of 1 to 100 nm and Nanoscale zero-valent iron represents a new generation of environmental remediation technologies, is non-toxic, abundant, cheap, easy to produce, and its reduction process requires little maintenance. Nonetheless, in order to diminish the tendency of aggregation, nanoscale zero-valent iron is often coated with surfactants. Most surfactants are chemically synthesized from petrochemical sources, they are slowly or partially biodegradable, while offer low harm to humans, such compounds can influence plants and animals. To decrease the use of chemical methods green synthesis and stabilization of metallic nanomaterials viable option. Biosurfactants can potentially replace virtually any synthetic they are extracellular compounds produced by microbes such as by bacteria and grown on different carbon sources containing hydrophobic/hydrophilic substrates. The biosurfactants have a wide variety of chemical structures and surface properties and among them is the ... (Complete abstract click electronic access below)
Doutor
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Faure, Bertrand. "Particle interactions at the nanoscale : From colloidal processing to self-assembled arrays." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-79129.
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Nanostructured materials are the next generation of high-performance materials, harnessing the novel properties of their nanosized constituents. The controlled assembly of nanosized particles and the design of the optimal nanostructure require a detailed understanding of particle interactions and robust methods to tune them. This thesis describes innovative approaches to these challenges, relating to the determination of Hamaker constants for iron oxide nanoparticles, the packaging of nanopowders into redispersible granules, the tuning of the wetting behavior of nanocrystals and the simulation of collective magnetic properties in arrays of superparamagnetic nanoparticles. The non-retarded Hamaker constants for iron oxides have been calculated from their optical properties based on Lifshitz theory. The results show that the magnitude of vdW interactions in non-polar solvents has previously been overestimated up to 10 times. Our calculations support the experimental observations that oleate-capped nanoparticles smaller than 15 nm in diameter can indeed form colloidally-stable dispersions in hydrocarbons. In addition, a simple procedure has been devised to remove the oleate-capping on the iron oxide nanoparticles, enabling their use in fluorometric assays for water remediation, with a sensitivity more than 100 times below the critical micelle concentration for non-ionic surfactants. Nanosized particles are inherently more difficult to handle in the dry state than larger micron-sized powders, e.g. because of poor flowability, agglomeration and potential toxicity. The rheology of concentrated slurries of TiO2 powder was optimized by the addition of sodium polyacrylate, and spray-dried into fully redispersible micron-sized granules. The polymer was embedded into the granules, where it could serve as a re-dispersing aid. Monte Carlo (MC) simulations have been applied to the collective magnetic behavior of nanoparticle arrays of various thicknesses. The decrease in magnetic susceptibility with the thickness observed experimentally was reproduced by the simulations. Ferromagnetic couplings in the arrays are enhanced by the finite thickness, and decrease in strength with increasing thickness. The simulations indicate the formation of vortex states with increasing thickness, along with a change in their orientation, which becomes more and more isotropic as the thickness increases.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.
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Busch, Jan Philip [Verfasser], and Sascha Eric [Akademischer Betreuer] Oswald. "Investigations on mobility of carbon colloid supported nanoscale zero-valent iron (nZVI) for groundwater remediation / Jan Philip Busch ; Betreuer: Sascha Eric Oswald." Potsdam : Universität Potsdam, 2015. http://d-nb.info/1218601876/34.
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Wei, Caijie, and 魏才倢. "Calcium-based coating on the surface of nanoscale zero-valent iron (nZVI) for improvement of its stability and transport in environmental remediation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/197497.
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Zero valent iron (ZVI) has demonstrated its reactivity and effectiveness for in-situ groundwater and soil remediation. The potential of the high reducing activity of nanoscale ZVI (nZVI) for environmental decontamination has attracted more attentions in recent years, as nZVI may be injected with water to the pollution sites for in-situ remediation. However, rapid oxidation and instant agglomeration of nZVI make it difficult for large-scale engineering application. Effort has been made to improve the stability and mobility of nZVI for effective in-situ remediation. In the present study, a novel Ca-based surface coating method has been developed for protection of nZVI and enhancement of its transport in environmental applications.
A simple thermal deposition method was employed to coat a Ca-based layer on the surface of micro- or nano- ZVI particles in water or methanol environment. According to microscopic observations, Ca(OH)2 nano-layer was formed on the ZVI surface. A clear core-shell structure was observed for the coated nZVI/Ca(OH)2 particles based on the TEM observations. The Ca(OH)2 coating layer had a thickness about one fifth of the nZVI diameter and the Ca to Fe ratio was below 0.2. With the Ca(OH)2 shell, nZVI particles can be effectively protected against corrosion according to the standard natural spray corrosion tests. Thus, the Ca(OH)2 coating layer is able to greatly improve the stability of nZVI during storage, transportation and application. In addition, based on the result of the dissolution tests, the Ca(OH)2 shell could be readily dissolved in water with a low Ca content or a low ionic strength. After dissolution of the Ca(OH)2 shell, the reactivity of nZVI was found to be at the similar level as bare nZVI, which could remove Cr(VI) from water by more than 90% in about 20 min. The pseudo-first order rate constants for Cr(VI) reduction by bare nZVI and nZVI/ Ca(OH)2 after shell dissolution were 0.064 and 0.072 min-1, respectively.
Moreover, the Ca(OH)2 coating shell would not only function as a protection layer but also improve the mobility of nZVI particles in in-situ applications. The aggregation and sedimentation of nZVI/Ca(OH)2 particles became considerably slower compared to bare nZVI without the coating. Clean-bed water filtration tests were conducted with sand and glass columns to evaluate the mobility and transport of nZVI in porous media. The results show that bare nZVI in the particle suspension deposited mostly at the top of the filters with little penetration. In comparison, the nZVI/Ca(OH)2 particles were able to penetrate through the filter media during the filtration process, and the dark iron particles could fill up the entire filter columns. The penetration rate increased from nearly 0 m/hr for bare nZVI to 0.43 m/hr for nZVI/Ca(OH)2 through the filter media. The Ca-based coating materials are known as of low cost and environmentally friendly. Thus, the new coating method developed in this study provides a cost-effective means for both the protection of nZVI and improvement of its transport and delivery in porous media for environmental decontamination.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
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Busch, Jan [Verfasser], and Sascha [Akademischer Betreuer] Oswald. "Investigations on mobility of carbon colloid supported nanoscale zero-valent iron (nZVI) for groundwater remediation / Jan Philip Busch ; Betreuer: Sascha Eric Oswald." Potsdam : Universität Potsdam, 2015. http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-76873.
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Busch, Jan [Verfasser], and Sascha Eric [Akademischer Betreuer] Oswald. "Investigations on mobility of carbon colloid supported nanoscale zero-valent iron (nZVI) for groundwater remediation / Jan Philip Busch ; Betreuer: Sascha Eric Oswald." Potsdam : Universität Potsdam, 2015. http://d-nb.info/1218601876/34.
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Digiacomo, Flavia [Verfasser], and T. [Akademischer Betreuer] Neumann. "Mobility and Reactivity of Sulfate Green Rust and Sulfidized Nanoscale Zerovalent Iron for In-Situ Remediation of Chromium Contaminated Sites / Flavia Digiacomo ; Betreuer: T. Neumann." Karlsruhe : KIT-Bibliothek, 2021. http://nbn-resolving.de/urn:nbn:de:101:1-2021091505003064178729.
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Kaifas, Delphine. "Déchloration réductive par les nanoparticules de fer zéro-valent : une solution innovante pour la réhabilitation des aquifères souterrains contaminés par le trichloroéthylène." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4320.
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Les récents progrès en matière de nanotechnologies ont permis d'élaborer de nouveaux matériaux aux propriétés physico-chimiques uniques tels que les nanoparticules de fer zéro valent (NPFe0). Ces nanoparticules ont prouvé leur efficacité pour dégrader les composés organiques chlorés comme le trichloroéthylène (TCE), cependant leur transport dans les milieux poreux est souvent limité. Une solution pour pallier à ce problème est de modifier leur surface par adsorption de molécules organiques. Toutefois, cet enrobage modifie la réactivité des NPFe0 vis-à-vis du TCE, ce qui peut potentiellement affecter l'efficacité du traitement. Ainsi, le premier volet de cette thèse concerne l'étude de la réactivité de NPFe0 brutes ou modifiées par des polyélectrolytes anioniques vis-à-vis du TCE. Cette réactivité a été évaluée au travers des cinétiques de dégradation du TCE et de ses produits de transformation.D'autre part, les eaux souterraines contiennent souvent des espèces dissoutes réductibles pouvant réagir avec Fe0. Ces dernières peuvent affecter la réactivité des NPFe0 vis-à-vis du polluant ciblé et donc l'efficacité du traitement de dépollution. Le deuxième volet de cette thèse porte sur l'effet de deux accepteurs d'électrons (CrVI et NO3-) sur la réactivité des NPFe0 brutes et modifiées. Enfin, le troisième volet de cette thèse concerne l'évaluation de la réactivité des NPFe0 vis-à-vis du TCE dans un cas « réel », afin de valider la technique de dépollution. Une étude pilote et une application in situ ont ainsi été menées sur un site industriel dont l'eau souterraine est contaminée par le TCE (polluant ciblé) avec de fortes teneurs en CrVI et NO3-Recent advances in nanotechnology have led to the development of new materials with unique physicochemical properties such as nanoscale zero valent iron particles (nZVI). These nanoparticles proved their efficiency to degrade chlorinated organic compounds such as trichlorethylene (TCE), but their migration in porous media is often limited. To overcome this problem, a solution is to modify their surface by adsorption of organic molecules. However, this coating modifies the reactivity towards TCE, which can potentially affect the treatment efficiency.Thus, the first part of this PhD focuses on the reactivity of nZVI (bare or modified by anionic polyelectrolytes) towards TCE. This reactivity was evaluated through the TCE degradation kinetics rates and its transformation products.In addition, groundwaters often contain reducible species that can react with dissolved Fe0. These last species may affect the reactivity of nZVI towards the target pollutant and therefore the remediation efficiency. The second part of this PhD focuses on the effect of two electron acceptors (CrVI and NO3-) on the reactivity of bare and modified nZVI.Finally, the third part of this PhD presents the assessment of the reactivity of nZVI towards TCE in a "real" case, in order to validate the remediation process. A pilot study and in situ application have been carried out on an industrial site which groundwater is contaminated with TCE (targeted pollutant) with high levels of CrVI and NO3-
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Тобілко, Вікторія Юріївна. "Розробка сорбційних технологій захисту вод від забруднення важкими металами та радіонуклідами." Doctoral thesis, Київ, 2016. https://ela.kpi.ua/handle/123456789/16336.
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Робота присвячена розробці сорбційних технологій захисту вод від забруднення важкими металами та радіонуклідами з використанням композиційних матеріалів на основі природних глинистих мінералів.
Одержано композиційні сорбенти на основі природних глинистих мінералів з нанесеним шаром нанорозмірного Fe0, (окси)гідроксидів заліза(ІІІ) та мікроводоростей Chlorella vulgaris і Scenedesmua asutus. Встановлено значне підвищення сорбційних характеристик одержаних матеріалів щодо сполук Со(ІІ), Cr(VI) та U(VI) порівняно з вихідними мінералами.
Вивчено процеси формування поруватої структури шаруватих силікатів при гранулюванні. Досліджено сорбційну здатність гранул по відношенню до іонів U(VI) в розчинах. Показана ефективність використання палигорськіту з нанесеним шаром нанорозмірного Fe0 при створенні в шарах грунту сорбційних екранів для захисту підземних вод від забруднення. Проведено дослідну перевірку ефективності очищення реальних підземних вод від сполук U(VI) з використанням композиційних сорбентів. Запропоновано технологічну схему одержання сорбційних матеріалів.
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Mendes, Rafael Gregorio. "Synthesis, characterization and toxicological evaluation of carbon-based nanostructures." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-186839.
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The synthesis, characterization and biological evaluation of different graphene-based nanoparticles with potential biomedical applications are explored. The results presented within this work show that eukaryotic cells can respond differently not only to different types of nanoparticles, but also identify slight differences in the morphology of nanoparticles, such as size. This highlights the great importance of the synthesis and thorough characterization of nanoparticles in the design of effective nanoparticle platforms for biological applications. In order to test the influence of morphology of graphene-based nanoparticles on the cell response, nanoparticles with different sizes were synthesized and tested on different cells. The synthesis of spherical iron-oxide nanoparticles coated with graphene was accomplished using a colloidal chemistry route. This synthesis route was able to render nanoparticle samples with narrow size distributions, which can be taken as monodispersed. Four different samples varying in diameter from 10 to 20 nm were produced and the material was systematically characterized prior to the biological tests. The characterization of the material suggests that the iron oxide nanoparticles consist of a mix of both magnetite and maghemite phases and are coated with a thin graphitic layer. All samples presented functional groups and were similar in all aspects except in diameter. The results suggest that cells can respond differently even to small differences in the size of the nanoparticles. An in situ study of the coating of the iron-oxide nanoparticles using a transmission electron microscope revealed that it is possible to further graphitize the remaining oleic acid on the nanoparticles. The thickness of the graphitic coating was controlled by varying the amount of oleic acid on the nanoparticles. The in situ observations using an electron beam were reproduced by annealing the nanoparticles in a dynamic vacuum. This procedure showed that it is not only possible to coat large amounts of iron oxide nanoparticles with graphene using oleic acid, but also to improved their magnetic properties for other applications such as hyperthermia. This study therefore revealed a facile route to grow 2D graphene takes on substrates using oleic acid as a precursor. The synthesis of nanographene oxide nanoparticles of different sizes was in a second approach accomplished by using the Hummers method to oxidize and expand commercially available graphite. The size of the oxidized graphite was adjusted by sonicating the samples for different periods of time. The material was also thoroughly characterized and demonstrated to have two distinctive average size distributions and possess functional groups. The results suggest that different size flakes can trigger different cell response. The synthesis, characterization and biological evaluation of graphene nanoshells were performed. The graphene nanoshells were produced by using magnesia nanoparticles as a template to the graphene nanoshells. The coating of magnesia with graphene layers was accomplished using chemical vapor deposition. The nanoshells were obtained by removing the magnesia core. The size of the nanoshells was determined by the size of the magnesia nanoparticles and presented a broad size distribution since the diameter of the magnesia nanoparticles could not be controlled. The nanoshells were also characterized and the biological evaluation was performed in the Swiss Federal Laboratories for Materials Science and Technology (EMPA), in Switzerland. The results suggest that despite inducing the production of reactive oxygen species on cells, the nanoshells did not impede cell proliferationDie Herstellung, Charakterisierung und biologische Auswertung von verschiedenen Graphen-basierten Nanopartikeln mit einer potenziellen biomedizinischen Anwendung wurden erforscht. Die vorgestellten Ergebnisse im Rahmen dieser Arbeit zeigen, dass eukaryotische Zellen unterschiedlich reagieren können, wenn sie mit Nanopartikeln unterschiedlicher Morphologie interagieren. Die Zellen können geringe Unterschiede in der Morphologie, insbesondere der Größe der Nanopartikeln, identifizieren. Dies unterstreicht den Einfluss der Herstellungsmethoden und die Notwendigkeit einer gründlichen Charakterisierung, um ein effektives Design von Nanopartikeln für biologische Anwendungen zu erreichen. Um den Einfluss der Größe von Graphen-basierten Nanopartikel auf das Zellverhalten zu erforschen, wurden verschiedene Graphen-beschichte Eisenoxid-Nanopartikelproben durch eine kolloidchemische Methode hergestellt. Dieses Herstellungsverfahren ermöglicht die Synthese von Nanopartikeln mit engen Größenverteilungen, die als monodispers gelten können. Vier Proben mit unterschiedlichen Durchmessern (von 10 bis 20 nm) wurden hergestellt und vor den biologischen Untersuchungen systematisch charakterisiert. Die Probencharakterisierung deutet auf eine Mischung aus Magnetit- und Maghemit-Kristallphasen hin, außerdem besitzen die Nanopartikel eine dünne Graphitschicht. Die spektroskopischen Ergebnisse auch zeigen außerdem, dass alle Proben funktionelle Gruppen auf ihrer Oberfläche besitzen, sodass sie in allen Aspekten, außer Morphologie (Durchmesser), ähnlich sind. Die biologischen Untersuchungen deuten darauf hin, dass Zellen unterschiedliche Größen von Eisenoxid-Nanopartikeln reagieren können. Ein in situ Untersuchung der Beschichtung der Eisenoxid-Nanopartikel wurde mit einem Transmissionelektronenmikroskop durchgeführt. Die Ergebnisse zeigen, dass eine dünne Schicht von Ölsäure aus dem Syntheseprozess auf den Nanopartikeln verbleibt. Diese Schicht kann mit einem Elektronstrahl in Graphen umgewandelt werden. Die Dicke der Graphitschicht auf den Nanopartikeln kann durch die Menge der eingesetzten Ölsäure kontrolliert werden. Die in situ Beobachtungen der Graphenumwandlung konnte durch erhitzen der Nanopartikeln in einem dynamischen Vakuum reproduziert werden. Das Brennen der Eisenoxid-Nanopartikel ermöglicht nicht nur die Graphitisierung der Ölsäure, sondern auch eine Verbesserung der magnetischen Eigenschaften der Nanopartikel für weitere Anwendungen, z. B. der Hyperthermie. Die Umwandlung der Ölsäure in Graphen konnte so als relativ einfaches Verfahren der Beschichtung von zweidimensionalen (2D) Substraten etabliert werden. Die Herstellung von Nanographenoxid mit unterschiedlichen Größen wurde mit der Hummers-Method durchgeführt. Die unterschiedlichen Größen der Nanographenoxidpartikel wurde durch eine Behandlung in Ultraschallbad erreicht. Zwei Proben mit deutlicher Verteilung wurden mit mehreren Verfahren charakterisiert. Beide Proben haben Nanographenoxid Nanoteilchen mit verschiedenen funktionellen Gruppen. Die biologische Charakterisierung deutet darauf hin, dass unterschiedliche Größen des Nanographens ein unterschiedliches Zellverhalten auslösen. Abschließend, wurde die Herstellung, Charakterisierung und biologische Auswertung von Graphen-Nanoschalen durchgeführt. Die Graphen-Nanoschalen wurden mit Magnesiumoxid-Nanopartikeln als Template hergestellt. Die Beschichtung des Magnesia mit Graphen erforgte durch die chemische Gasphasenabscheidung. Die Nanoschalen wurden durch Entfernen des Magnesia-Kerns erhalten. Die Größe der Nanohüllen ist durch die Größe der Magnesia-Kerns bestimmt und zeigt eine breite Verteilung, da der Durchmesser der Magnesiumoxid-Nanopartikel gegeben war. Die Nanoschalen wurden ebenfalls mit Infrarot- und Röntgen Photoemissionspektroskopie charakterisiert und die biologische Bewertung wurde im Eidgenössische Materialprüfungs- und Forschungsanstalt (EMPA) durchgeführt, in der Schweiz. Die Ergebnisse zeigen, dass zwar die Produktion von reaktiven Sauerstoffspezies in den Zellen ausgelöst wird, diese sich aber weiterhin vermehren können
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Sun, Yuan-Pang. "Dispersion of nanoscale iron particles /." Diss., 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3215855.
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Chen, Shu-Ching, and 陳舒罄. "Synthesis and Application of Nanoscale Zero-Valent Iron." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/43715975915445887701.
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碩士長庚大學
化工與材料工程學系
99
In this research, nanoscale zero-valent iron (nZVI) was synthesized by sodium borohydride and chloride tetrahydrate in a rotating packed bed (RPB) equipped with blade packings. The differences of physical properties between RPB-nZVI and commercial nZVI (CBT-nZVI) were investigated. Moreover, to compare the chemical properties, two kinds of nZVI were used to degrade C. I. Reactive Red 2 (RR2). The FE-SEM and TEM images showed that CBT-nZVI was irregular in shape and piles arranged, RPB-nZVI was almost spherical and existed as chain-like aggregates. The BET surface area of CBT-nZVI and RBP-nZVI were 15.8 m2/g and 17.1m2/g, respectively. The XRD analysis revealed that CBT-nZVI consisted of Fe0 and Fe3O4 crystal structures. However, only Fe0 crystal structure was observed in RPB-nZVI. The EDX analysis indicated that RPB-nZVI and CBT-nZVI had Fe of 87.6 at% and 66.3 at%, respectively. Moreover, the XPS analysis demonstrated that RPB-nZVI had 12% Fe0 within the particle surface. However, Fe0 was not found within the surface of CBT-nZVI. The experimental results of RR2 degradation showed that the superior degradation efficiency using RPB-nZVI was achieved at pH 4, 30C, and nZVI dosage of 0.30 g/L. In the degradation conditions as described above, RR2 degradation efficiencies of RPB-nZVI and CBT-nZVI were 98% and 16%, respectively. Therefore, RPB-nZVI exhibited a higher activity to degrade RR2 than CBT-nZVI.
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Yang, Shih-Wei, and 楊士衛. "Preparation of nanoscale iron suspensionfor in-situ applications." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/12335132874514089580.
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碩士國立臺灣大學
環境工程學研究所
94
Chlorinated hydrocarbons such as trichloroethene, tetrachloroethylene, etc. can leach into groundwater and form dense non-aqueous phase liquid（DNAPL）. The commonly used method of Pump and Treat is known to be time-consuming and costly; therefore, the objective of this research is to develop a more efficient and cost-effective groundwater remediation method. It is important to note that USEPA has already claimed that permeable reactive barrier is a mature and standard technology. With zero-valent iron as its principal filling and the chemical mechanism of chlorinated hydrocarbon removal fully understood, an integration with the nano-technology may enhance its performances. Metal particles can be nanonized to be more active and become easier to spread through porous media. When nanoscale zero-valent iron is injected into the underground aquifer through the injection well, an “iron wall” is formed to prevent the contaminants from further migrating. In highly-concentrated metallic nanoparticle suspension, with the distance between particles very small, particle aggregations tend to happen, which in turn will slow down their distribution in groundwater. To solve this problem, this research first used different stabilizing dispersants to see how iron particles were dispersed in the suspension. Next, optimal results from the batch experiment were applied to make a nanoscale iron suspension by means of continuous circulation, with sodium borohydride and ferrous sulfate as raw materials, and CDE, a stabilizing dispersant, added into sodium borohydride solution (final concentration 5000mg/L). This suspension was maintained 100% of nanoparticle suspension stability for four days. The particle sizes measured to range from 300 nm to 600 nm, with the use of the Zetasizer. With a scanning electronic microscopy, particle sizes were all found to be less than 100nm and the particles seemed to be wrapped in surfactant. The last stage of the experiment with the nanoscale iron suspension was to test its percolation rates through soil columns and TCE dechlorination rates. The percolation results for soil columns that were 10cm, 20cm and 40 cm long were 33%, 19.3%, and 8.2%, respectively; and the decay coefficient (k) of the suspended nanoscale iron particles per unit distance was 0.0963 cm-1. By injecting the solution laden with TCE into soil columns containing nanoscale iron, the dechlorination rate is 54.4%. To heighten the percolating ability of nanoscale iron particles through soil columns, less doses of sodium borohydride solution is suggested for future experiments.
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Hsu, Hung-Der, and 徐宏德. "Nanoscale Iron Particles for the Degradation Reaction of Nitrate." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/94327472915602694452.
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碩士國立臺北科技大學
環境規劃與管理研究所
92
Treatment of nitrate contaminants by zero-valent iron (ZVI) represents one of the latest innovative technologies for environmental remediation. This research uses nanoscale ZVI（the size range of 1-20 nm, specific surface area of 9.43 m2/g）for transformation of nitrate for their advantages of higher surface area and reactivity. Nanoscale ZVI is not available in the market and has to be produced by the theoretical methods. Two methods of producing nanoscale iron particles are chosen to use in this research. One is an electro-chemical method and the other method is chemical method. TEM, SEM, B.E.T. and ESCA analysis were used for identification of nanoscale iron production. The nanoscale ZVI experiment was conducted in batch experiments for nitrate reduction. The discussed experimental factors include pH buffered or not, initial pH, dosage of nanoscale ZVI and initial nitrate concentration to compare the removal efficiency for nitrate reduction. Kinetics effects for nitrate removal by nanoscale ZVI were determined. The results showed that the degradation reaction of nitrate was controlled by pH. When the initial pH was controlled at 4, 5, 6 and 7, the faster rates of nitrate reduction were shown at lower pH, and controlled pH experiment was shown better efficiency than pH uncontrolled experiment. The reactions were shown pseudo-first order reaction. The pseudo first order reaction rate constants were 0.369 hr-1, 0.310 hr-1, 0.253 hr-1 and 0.201 hr-1, respectively, and reaction rate constant of uncontrolled pH experiment was 0.199 hr-1. Under similar experimental conditions, the faster rates of nitrate reduction were in higher dosage of nanoscale ZVI. Reaction rate constants were increased with higher ZVI nitrate ratio. Comparing with microscale and nanoscale ZVI, microscale ZVI converted nitrate to ammonia complete, but nanoscale ZVI converted nitrate to ammonia partially. The ammonia was about 36 ~ 45 %. The concentration of soluble iron were lower 0.9 mg/L, and ESCA analysis were used for identification of surface species for nanoscale iron react with nitrate. The results showed that the iron belong to Fe2O3. Compare the convertibility of nitrate dose for microscale and nanoscale ZVI. Per gram nanoscale ZVI can convert nitrate dose of 28.8 g, and per gram microscale ZVI can convert nitrate dose of 24.42 g. The higher convertibility of nitrate was shown for lower pH experiment.
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Tai, Yu-Tsung, and 戴侑宗. "Reduction of Decabrominated Diphenyl Ether by Nanoscale Zero-valent Iron." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/48297731697890544816.
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碩士中興大學
土壤環境科學系所
94
Polybrominated diphenyl ethers (PBDEs) are widely used as flame retardants in inflammables to ensure the life and property safety by decreasing the risk of fire accidents. PBDEs have been detected in human, wildlife, marine, and freshwater sediments. PBDEs become important environmental organic pollutants but the degradation studies of PBDEs in the environment are still limited. In this study, the chemical debromination of DBDE (Decabrominated diphenyl ether) by zero-valent iron (ZVI) was studied. A scanning electron microscopy and a photon correlation spectroscopy were performed to characterize the surface properties and particle size of nanoscale ZVI, respectively. The nanoscale ZVI existed as spherical particles averaging 20~50 nm in diameter and its surface area was 52.0 m2/g. Within 40 minutes over 80 % of DBDE was transformed into lower bromo congeners by nanoscale ZVI under ambient conditions. During the initial reaction period (< 20 minutes), nonabromo BDEs were the most abundant products but hexa to heptabromo congeners were dominant after 130 minutes. The effects of particle sizes of zero-valent iron, temperature (5, 25, and 45 ℃), pH value (5, 7, 8, and 10), and the existence of inorganic anions (Cl-, HCO3-, and H2PO4-) and cations (Na+, Cu2+, and Fe3+) in solutions on the dehalogenation were evaluated. For nanoscale ZVI, the pseudo-first-order DBDE debromination rate constant (0.0583 min-1) was significantly faster than that of microscale ZVI (0.0077 min-1) due to the higher surface area and reactivity of nanoscale iron particles. The debromination rate constants of DBDE increased with the decreasing of aqueous pH values and with the increase of temperature. For anions, a high concentration of chloride ions enhanced the debromination of DBDE, whereas phosphate and carbonate ions hindered the debromination process. The cation species also affected the reduction reaction by ZVI except Na+. The debromination rate constants of DBDE increased in the presence of Cu2+ and decreased in the presence of Fe3+. Lugang and Longgang soil solutions and Lugang and Longgang soils were chose as soil systems to evaluate the debromination rate of DBDE by nanoscale ZVI. The reduction rates of DBDE by nanoscale ZVI in soil solutions and soils were slower than those in pure water. Comparing the reaction rates between Longgang and Lugang soils, the reduction rate of DBDE in Longgang soil was faster than that in Lugang soil probably due to the lower pH of Loggang soil. The debromination pathway of DBDE by nanoscale ZVI was proposed via the analysis of byproducts. Nanoscale ZVI has the high potential values to remediate PBDEs in the environment.
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TENG, CHEN-YAO, and 鄧陳堯. "Research and Development of Cloisite – Nanoscale Zero Valent Iron Composites." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/e2azq6.
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碩士國立高雄應用科技大學
化學工程與材料工程系碩士在職專班
104
For the effective degradation efficiency of heavy metal ions in wastewater, the ion exchange technique was utilized to produce a high performance of Cloisite - nanoscale zero valent iron (Cloisite-nZVI) composite, in this study. Furthermore, the Box-Behnken design was used to deal the preparatory conditions, such as the concentration of ferric ion, molar ratio of [F2+] / [NaBH4], stirring speed and feeding rate of NaBH4 etc., for the synthesis of the Cloisite-nZVI composited materials. Analysis by Design Expert software, the optimal conditions for the preparation of Cloisite-nZVI were obtained at an iron concentration of 1.5 M, a molar ratio of Fe2+ / NaBH4 at 1, a stirring rate at 700 rpm and a feed rate of NaBH4 at 1.22 mL/s. The iron concentration of Cloisite-nZVI prepared by the optimal conditions is predicted at 1794 ppm. Moreover, the experimental results confirmed that the iron ion concentration of 1845 ppm, and demonstrated the degradation efficiency of potassium dichromate at 87 %.
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Huang, hong-wun, and 黃鴻文. "Microwave-induced Degradation of Chlorobenzene on Nanoscale Zero Valence Iron." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/t9cn5h.
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碩士國立高雄第一科技大學
環境與安全衛生工程所
96
Microwave energy is used in this research to enhance the oxidation rate of nano-scale zero-valence iron for rapidly degraded of chlorobenzene in aqueous solution. The nano-scale iron has been pre-treated to remove surface oxides thus increasing the reactive surface; the treatment efficiency using 1 g iron will increases 5% (from 0% to 5 % and 15% to 20%) of chlorobenzene degradation. One gram of nano-iron has 20% higher degradation rate than micro-scale iron powder because the former has higher reactivity per unit surface and hence more specific surface area. If the quantity of nano-iron is doubled from 1 g to 2 g, the chlorobenzene degradation will increase from 20% to 32% ; the initial pH of nano-scale zero-valence iron suspension will not adversely affect the degradation rate; lower initial pH values show higher degradation rates. However, with increasing reaction time, the degradation rate decreases and the final rate is not much different from those with other pH initial values. The degradation rates are 21% for pH 4, 20% for pH 7 and 18% for pH 10 ; the solution temperature will enhance the molecular kinetic energy, and the number of collision per unit time, thus, leading to higher chlorobenzene degradation rate. When the solution temperature is kept at 40oC, 50 oC, and 60 oC, the degradation rates are 29%, 35%, and 42%, respectively. With microwave energy being used to enhance the iron activity, the larger surface of nano-scale iron will absorb more microwave energy to degraded 65% chlorobenzene for non-scale iron and 61% for micro-scale iron. If the nano-scale iron is suspended in solution, it has a larger surface area to absorb the microwave energy thus raising the degradation rate from 83% to 92%. Longer microwave irradiation time will allow the zero-valence iron to absorb more energy. When the irradiation time is kept at 20 seconds, the degradation rate is 83% as compared to 65% for 10 seconds. Higher microwave energy causes more degradation of chlorobenzene; the efficiencies are 71% for 150 watts, 83% for 250 watts and 92% for 350 watts. These results demonstrate that the microwave will enhance the efficiency of nano-scale zero-valence iron to degraded chlorobenzene and reduce the reaction time.
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Hao, Chung-Ping, and 郝仲平. "Removal of Diisobutyl Phthalate from Aqueous Solution by Nanoscale Zero-Valent Iron." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/64057483107490792425.
Full textAbstract:
碩士嘉南藥理科技大學
環境工程與科學系碩士班
96
Phthalate acid esters (PAEs) are usually and widely used as plasticizers. Among the PAEs, Diisobutyl phthalate (DIBP) is very popular and frequently used. According to the literature, PAEs are suspected as environmental endocrine disrupter (EED), posing a threat to the human health. The feasibility of removing DIBP by sequential batch nanoscale zero valent iron reactor assisted with electric field from aqueous solution was evaluated in the present work. It was found that the solubility of DIBP in the aqueous solution was influenced by solution pH, decreasing from 8.05 mg / L at pH 9 to 3.05 mg / L at pH 3. In addition, the removals of DIBP were 63.38 %, 69.19 % and 52.53 %, respectively, in the first batch experiments when the solution was controlled at pH 3, 4, and 5, respectively with a initial DIBP concentration of 8.05 mg/L, NZVI dosage of 1000 mg/L and without aeration. In the second batch experiments, the removals of DIBP were found to be 60.05 %, 69.69 %, and 53.88 %, respectively. The result showed that the optimum solution pH for the removal of DIBP was 4. The result showed the removals of DIBP were 69.60 % 、73.00 % and 50.00 %, respectively, in the aeration experiments when the solution was controlled at pH 3, 4, and 5, respectively with a initial DIBP concentration of 8.05 mg/L and NZVI dosage of 200mg/L. The removals of DIBP were 85 %, 85 % and 60 %, respectively, in the aeration experiments when the solution was controlled at pH 3, 4, and 5, respectively with a initial DIBP concentration of 8.05 mg/L and NZVI dosage of 1000mg/L. The result showed that the optimum solution pHs for the removals of DIBP were 3 and 4.
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Yang, Chia-wei, and 楊嘉葦. "Removal of Hydrogen Sulfide with Nanoscale Zero-Valent Iron from Piggery Wastewater." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/15412241925648433721.
Full textAbstract:
碩士國立高雄大學
土木與環境工程學系碩士班
99
The removal of hydrogen sulfide from piggery wastewater by nanoscale zero-valent iron (NZVI) was investigated. NZVI was prepared by the wet chemical synthesis method. Results indicate that the degradation efficiency increases with increasing NZVI concentration and DO. Results revealed that the hydrogen sulfide removal efficiency using NZVI particles was highly dependent on pH with maximum removal efficiency at pH 4. We used TEM, XRD, TGA, FTIR to characterize material changes before and after experiment. Kinetics analysis in batch studies demonstrates that the removal of hydrogen sulfide by nanoscale Fe0 fits well with the second - order reaction with respect to hydrogen sulfide concentration. A maximum adsorption capacity of 3333 mg/g were determined for hydrogen sulfide removal at pH = 7. At pH = 12, sulfide can be sorbed onto the iron particle via formation of surface complexes. FeOOH react directly with hydrogen sulfide. At pH = 4, iron nanoparticles react with water to release ferrous iron, that further precipitates with sulfide (S2-) to iron sulfide (FeS).
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Tsai, Jui-Chou, and 蔡瑞洲. "Transport of polyacrylic acid stabilized nanoscale zero valent iron in porous media." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/69980941005496821566.
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Chang, Yung i., and 張永宜. "Treatment of Trichloroethylene in Aqueous Solution Using Nanoscale Zero-Valent Iron Emulsion." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/6dbjqz.
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碩士國立中山大學
環境工程研究所
95
The objective of this research was to evaluate the treatment efficiency of a trichloroethylene(TCE)-contaminated aqueous solution and soil by combined technologies of the emulsified nanoscale zero-valent iron slurry (ENZVIS) and electrokinetic remediation process. Nanoiron was synthesized using the chemical reduction method by industrial grade chemicals. The synthesized nanoparticles contained elemental iron and iron oxide as determined by X-ray diffractmetry(XRD). Micrographs of FE-SEM have shown that a majority of nanoiron were in the size range of 30~50 nm. The stability study of food-grade soybean oil emulsion was conducted using six non-ionic surfactants and soybean oil. The results have shown that the emulsion prepared by mixed surfactants (Span 80 and Tween 40) and soybean oil yielded a better emulsion stability. Based on the above finding, the nanoiron slurry, soybean oil and aforementioned, mixed surfactants were used to prepare ENZVIS. Degradation of TCE by ENZVIS under various operating parameters was carried out in batch experiments. The experimental results have indicated that emulsified nanoiron outperformed nanoiron in TCE dechlorination rate. ENZVIS (0.75 g-Fe0/L) degradated TCE (initial conc.= 10 mg/L) down to 45 %. An increase of the oil dosage could improve the stability of the emulsion, but yielding a negative influence on degradation of TCE. Experimental results also showed that ENZVIS could remove TCE up to 94 % when pH=6. It was also formed that a higher TCE initial concentration would result in a higher TCE removal efficiency. In addition, using ENZVIS to degraded TCE-contaminated artificial groundwater has indicated that nitrate and carbonate of groundwater will suppress nanoiron reaction with TCE. Especially, a high concentration of carbonate in the reaction system might form a passive film or precipitates on nanoiron surface. This study further evaluated the treatment efficiency of combining ENZVIS and electrokinetic technology in treating a TCE-contaminated soil. Experimental conditions were given as follows:(1) initial TCE concentration in the range of 98~118 mg/kg; (2) an electric potential gradient of 1 V/cm; (3) a daily addition of 20 mL ENZVIS; and (4) a reaction time of 10 days. Experimental results have shown that an addition of ENZVIS to the anode reservoir of strongly acidic and oxidative environment would cause nanoiron to corrode rapidly and decrease TCE removal efficiency. On the other hand, an addition of ENZVIS to the cathode reservoir would enhance the degradation of TCE therein. In summary, an addition of ENZVIS to the cathod reservoir would yield the best TCE removal efficiency.
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HUANG, KAI-NING, and 黃楷甯. "Investigation of Tea Reducing Potential for Green Synthesis of Nanoscale Iron Particles." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/rp43a7.
Full textAbstract:
碩士國立臺北科技大學
環境工程與管理研究所
107
Green Chemistry, in the definition of IUPAC, is “design of chemical products and processes that reduce or eliminate the use or generation of substances hazardous to humans, animals, plants, and the environment.”. In present synthesis process, sodium borohydride is used as a reducing agent for zero-valent iron synthesis. Sodium borohydride is classified as a water-free substance, an acutely toxic substance, a corrosive skin substance, a reproductive toxic substance in the safety data sheet. If inadvertently contacted, it will cause severe skin burns and eye damage or harm to the reproductive capacity, fetus. Therefore, in this research, we study about tea, which replaces the use of sodium borohydride. Moreover, obtaining the best parameters preparing tea extract as an optimal reducing agent for the synthesis of zero-valent iron. This study is divided into two parts: First, investigation of tea, which include different type of teas (Biluochun, Ten Ren's, Alishan Black Tea), time (0.5 hours, 1 hour, 2 hours), temperature (25 ° C, 80 ° C, 100 ° C). This part is to know the relationship between the parameters, such as pH, ORP, COD, and the total polyphenol amount of the tea extract, and obtain the maximum reducing potential of the tea extract as the optimal green synthetic reducing agent. In order to further understand the effects of different tea leaves, FTIR, UV, HPLC, and CV were analyzed. Second, the investigation of green synthetic nano-zero-valent iron(G-nZVI). To prove the synthesis was successful, XRD, SEM, EDS, and FTIR analysis were used for determining. And to investigate the efficiency of G-nZVI synthesis, weight, and the hexavalent chromium removal efficiency was used for confirming. There are three parameters in tea extract characterization, which include Tea Type, Effect of Temperature and Effect of Time. The Tea Type results show that green tea got greater talent than black tea does. While green tea is polyphenol-riched and got higher value of pH, COD and reduction potential. The Effect of Temperature results shows that it does affect the parameters, such as the concentration of polyphenol, ORP, and COD., but it barely affects pH. The Effect of Time results show the concentration of polyphenol, pH, and ORP are independent, but COD depends on the tea type changed. The goal of this study is to investigate the optimal extraction conditions for preparing the tea extract. In order to replace NaBH4 as a reducing agent, dispersant and stabilizer for the synthesis of zero-valent iron. The parameters of the tea extract affecting the reducing power, such as the degree of tea fermentation, tea extraction conditions (temperature, time), the effects on the concentration of polyphenol, pH, ORP, COD, and the best parameters for green synthesis. This study uses green tea to synthesize zero-valent iron, which not only replaces the harmful chemicals in the present process but also combines Taiwanese native tea agriculture, which has considerable potential for the sustainable development of soil and water remediation.
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Tsai, Yi-An, and 蔡宜安. "Toxicity assessments of modified and unmodified nanoscale zerovalent iron to Caenorhabditis elegans." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/55689906296709382176.
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碩士國立臺灣大學
環境工程學研究所
102
Nanoscale zero-valent iron (NZVI) has been used for the remediation of contaminated groundwater as a reductant. In order to enhance its mobility, NZVI has been surface-modified with polymers or surfactants to increase its stability in aqueous phase. Hydrophobic modifiers will also improve the affinity of NZVI with non-aqueous phase liquids. Although great amount of NZVI may be to release to the environment, the fate and ecotoxicological effects of NZVI remain unclear. In this study we investigated the toxicity of bare NZVI, polyacrylic acid (PAA), polymethylmethacrylate (PMMA) or cetyltrimethylammonium bromide (CTAB) modified NZVIs in different solution phases, Fe2O3 nanoparticles and Fe2+ on nematodes, Caenorhabditis elegans (C. elegans), by using different toxic endpoint such as lethality, reproductivity and morphological change. Under acute exposure (24 h), C. elegans were slightly affected by various types of NZVI suspensions, Fe2O3 and Fe2+. After 48h of exposure, the lengths of C. elegans were affected by all types of NZVI suspensions, as well as Fe2+ solution. After 72h of expose, the reproductivity of C. elegans was significantly decreased by NZVI suspensions and Fe2+ solution. Fe2O3 showed no toxicity to C. elegans. We have also observed the ‘bag of worms’ phenotype, which is characterized by failed egg-laying and may occur in the stressed environment which is produced by the oxidation of NZVI and the release of Fe2+ and reactive oxygen species. From the observation under the microscope, we found that NZVI particles were attached on C. elegans and inside its intestinal track which would react with internal substances and produce ROS causing the toxicity. The experimental results showed that although the stable NZVIs may not cause death in C. elegans, but it does pose adverse effects other than death, which are the potential impact of NZVI.
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Su, Chih-Gang, and 蘇致綱. "Evaluation of activated carbon supported nanoscale zero valent iron for treating trichloroethylene." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/17898274193271555157.
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碩士國立中興大學
環境工程學系所
97
Chlorinated solvents such as trichloroethylene (TCE) are among the most common soil and groundwater contaminants. If TCE, as a dense non-aqueous phase liquid, is accidently released in the subsurface, its presence would become a continuous source of contamination. Permeable reactive barrier (PRB) is a passive technology for in situ clean-up of groundwater contamination. Among reactive materials filled within PRB, zero valent iron (ZVI) and activated carbon (AC) are widely used reactive materials. ZVI undergoes reductive dechlorination of TCE when containments are in contact with ZVI surface. Therefore, specific surface area of ZVI is highly correlated with high reactivity. In addition, AC with high surface area and multiple surface functional groups is a good adsorbent for removing contaminants. In this study, a process of coating nano zero valent iron (nZVI) onto AC, namely nZVI/AC, was developed. Then evaluation of the synthesized nZVI/AC composites for remediating TCE contamination was conducted. The results present a successful approach of combining impregnation and borohydride reduction to synthesize nZVI/AC composites. SEM analysis demonstrates that the size of nZVI on AC synthesized under different calcined temperatures is about 50-100 nm. Furthermore, the addition of polyethylene glycol dispersant for preparation of nZVI/AV reveals no effect on nZVI particle size. However, a well dispersion of nZVI on AC is achieved. When comparing nZVI/AC to nZVI on degradations of TCE, nZVI/AC reveals higher percentage of dechlorination than using nZVI only. The used nZVI/AC composites can then be regenerated by carbothermal reduction process which can be an effective method to regenerate the synthesized nZVI/AC composites.
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Lin, Yu-Hao, and 林禹豪. "Transport Analysis of Stabilized Nanoscale Iron and Simulation of Naonoparticle Motion Trajectory." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/65899776190083684169.
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博士國立中興大學
環境工程學系所
98
This study modified the surface of nanoscale zero valent iron (NZVI) to synthesize the stabilized and mobile NZVI using two method. The first one is by carboxymethyl cellulose sodium (CMC) coating, and the other is to make NZVI encapsulated into the poly acrylic acid (PAA) vehicle. They are tilted as CNZVI and PNZVI, respectively. Furthermore, this study also synthesized the PFNZVI (PNZVI with finer sizes) using the method of heterogeneous nucleation to enhance the contaminant removal ability of NZVI. The mobility of NZVI in porous media will be evaluated by a series of column tests, and the impacts of groundwater parameters, such as flow velocities and ion strengths, on NZVI mobility will also be investigated. A NZVI trajectory model based on theory of force balance was also developed to simulate the movement of single NZVI particle in porous media, which could also used for evaluating the surface modification of NZVI. Current results reveal that PAA form a capsule-like gelling network to encapsulate NZVI (PNZVI), decrease the oxidation of NZVI in the air, and result in better mobility than CNZVI. However, when the Ca2+ concentration increases to 40 mM, the PAA gelling network is destroyed by Ca2+ and mobility of PNZVI decrease apparently. In addition, the analysis of trajectory model indicated that for unstabilized NZVI with 80nms diameter moves in porous media, the gravity effects of the particle can''t be neglected. The NZVI movement is dominated by the Brownian motion and most of the deposit occurred at the area of pore inlet. For stabilized NZVI, the particles kept away from the porous media due to electrosteric repulsion force, and no deposit is ever observed. Keyword : Nanoscale zero valent iron、carboxymethyl cellulose sodium、poly acrylic acid、mobility、motion trajectory
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Kang, Hui-Chieh, and 康惠傑. "Decomposition of Azo Dye in Aqueous Solution by Nanoscale Iron/Fenton/Ultrasound Process." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/71862953886022576627.
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碩士中臺科技大學
放射科學研究所
95
The purpose of this thesis is to evaluate the treatment of azo dyes in wasterwater using nanoscale iron/fenton /ultrasound process. There were two parts in this study, The first part was to predict the optimum conditions using Taguchi analytical methodology. The major parameters, including dosage of H2O2 , the concentration of Fe2+,the amount of nanoscale Fe added , treatment time and intial pH. The second one was to study the effect of surfactant and mixed dyes. Results show the optimal combination of parameters for nanoscale iron/fenton/ultrasound process were treatment time for 60min, the concentration of H2O2 and Fe2+ were 1.9×10-2 M and 1.2×10-3 M, the dosage of nanoscale Fe for 0.25g and initial pH at 2 .The efficiencies of decolorization and COD reduction were accomplished at optimum conditions as 99.91% and 63.36%,respectively. The solubility of dyes in water was enhanced by addition of surfactant (LEVALON L-450), but the degradation rate was decreased significantly. Furthermore, the treatment of mixed three different azo dyes solution under Fenton and nanoscale iron/fenton /ultrasound conditions were compared. The result has shown that the rate of COD reduction in the mixed dyes solution was four times as fast as that accomplished by Fenton alone. Keywords: Taguchi Method, Azo Dye, Nanoscale Fe, Fenton, COD
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Wu, Chun-Yi, and 吳駿逸. "Enhancement of the mobility of nanoscale zero-valent iron (nZVI) using Tween surfactants." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/85786743603130855974.
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碩士國立暨南國際大學
土木工程學系
102
In recent years, due to the underground storage tank spill, pipeline rupture, ground accidental oil spills, factory indiscriminate dumping, discharge of waste water treatment or perfusion without other causes of pesticides, organic solvents, petroleum hydrocarbons and other organic compounds in soil and groundwater causing serious pollution. nanoscale zero-valent iron(nZVI) was widely used on the relevant pollution remediation because of its high reactivity and strong reduction of groundwater,so it can effectively remove chlorinated organics, however, nanoparticles are in an unstable state, so the particles may reunited by collision or other factors the in situ, and that would obstructive in soil pore causing the decrease of treatment effect and limited remediation range. In this study, nanoscale zero-valent iron was modified by different dispersant (polyacrylic acid (PAA), Tween 20, Tween 40 and Tween 60) and different doses were used to enhance its mobility under the surface. In the first, sedimentation and string transmission experiment were used to assess the stability and transportability of the modified nanoscale zero-valent iron, and then confirmed their removal capacity of trichloroethylene(TCE) by batch experiments. Results show that while nano iron suspension were dispersed by 2% (v / v%) of the dispersant has better suspension and transportability. In the measurement of Dynamic Light Scattering(DLS),size of thus synthesized nZVI was 171.00 nm, and analysis of PAA modified nZVI measured two major peaks, 8.03 nm and 169.40 nm; nano-iron particles, which were dispersed by tween 20 has measured peaks of 4.22 nm, 5.63 nm, 6.22 nm, 24.15 nm, 87.76 nm, 1021.00 nm. Indicating that although after the distribution of tween 20 modified nZVI are not uniform but still smaller than the diameter of the bare iron. In terms of the suspension, PAA concentrations of either adding 0.5-5% (v / v%) can make the nano-iron particles suspension stable, and Tween series modified nZVI were almost fully precipitated in 30 minutes to 1 hour, however, it still better than bare iron that can only maintain about 5-10 minutes. In the test of transport effect in quartz sand columns, tween 20 modified nZVI was better than others, after penetration over 15 cm of quartz sand (porosity 43.90%), the concentration of nano-iron in drop out suspension was still 80.8% of stock solution. After analysis the zeta potential of each suspension,we knew that the modified suspensions were negatively charged in general the neutral condition, and most of the soil surface were negatively charged particles, so while the suspension flow through the soil pore the nano iron particles would not blocked to soil particles easily so that could improve their mobility. Degradation of trichloroethylene (TCE) by nZVI with different dispersant was carried out in batch experiments. Experimental results have shown that bare iron, PAA modified nZVI, and tween 20 modified nZVI have similiar TCE dechlorination rate, but the modified nZVI have better mobility, so they could enhance treatment efficiency in situ.
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Lerner, Robert. "The effects of biofilm on the transport of nanoscale zerovalent iron in the subsurface." Master's thesis, 2011. http://hdl.handle.net/10048/1851.
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This study examines the effects of Pseudomonas aeruginosa (PAO1) biofilm, with a concentration of cells similar to that reported for saturated aquifers, on the transport of poly(acrylic acid) stabilized nanoscale zero valent iron (pnZVI) in 14 cm long, saturated, laboratory packed columns, with ionic strengths (ISs) of 1 and 25 mmol NaCl. With biofilm, the retention of pnZVI increased with higher solution IS, while IS played no role in the retention of nanoparticles without biofilm. However, the Tufenkji-Elimelech correlation equation predicts 5% less pnZVI collisions in biofilm coated columns due to a sixfold reduction of the Hamaker constant. Also, DLVO energy considerations predict the most favorable attachment for uncoated porous media at the higher IS. Reasons for the disagreement between theory and experiment are shown to be due to the non-ideality of the biofilm system. This research indicates that current laboratory studies underestimate nanoparticle transport distances in the subsurface.Environmental Science
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Siddiqui, Shad Waheed. "Use of the Confined Impinging Jet Reactor for production of nanoscale Iron Oxide particles." Phd thesis, 2009. http://hdl.handle.net/10048/417.
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The confined impinging jet reactor gives efficient mixing performance as required for fast reactions. In this work the mixing performance of CIJR is characterized through three measures: estimates of the energy dissipation, micromixing efficiency based on the yield of a homogeneous (iodide-iodate) reaction and particle size resulting from a heterogeneous (iron oxide) precipitation reaction. Whereas product yield and energy dissipation are used to test operational robustness of CIJR, iron oxide model system is used to study the effect of feed flow rate (mixing) and reactant concentration on precipitate agglomerate size. Mixing and concentration effects on nucleation, particle growth and particle agglomeration are tracked to understand the agglomeration process. Various types of stabilizers and additive concentrations to limit particle agglomeration are also tested. Effects of in situ and post-reaction sonication on agglomerate size are also investigated. Efforts are made to determine variations in mixing efficiency the operational robustness of the scale-up (2X and 4X) geometries. Also efforts are made to identify scaling parameters and the limit on geometric scale-up for good mixing performance.
Energy dissipation is found to vary between 20 W/kg and 6800 W/kg in CIJR and decreases on scale-up at constant Reynolds number. The operation of the CIJR and the scale-up geometries is robust to changes in flow rate, exhibiting stable performance up to 30% difference in inlet flow rates. Reliable mixing performance is obtained until 2X scale-up, while at low flow rates, the jets fail to impinge in 4X scale-up, and sometimes failing to fill the reactor volume.
Iron oxide primary and agglomerate particles are seen to vary with flow rate and reactant concentrations. Largest primary particles (and smallest agglomerates) are obtained at high flow rates and high reactant concentrations, which indicate to size dependent agglomerative tendency of the primary particles. Stabilizers added in situ see limited success. Post-reaction sonication is helpful in dispersing soft agglomerates, but in situ sonication shows no significant reduction in agglomerate size with or without stabilizer. Primary particles are understood to agglomerate due to collisions induced by Brownian motion, simple shear and velocity fluctuations in turbulent flows. These collision mechanisms operate at different length scales in the fluid mass.Chemical Engineering
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Tan, Shih-Wei, and 覃世偉. "Toxicity assessments of coated and uncoated nanoscale zerovalent iron in medaka (Oryzias latipes) larvae." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/43459528763534767236.
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碩士國立臺灣大學
農業化學研究所
99
Nanoscale zerovalent iron (nZVI) has been increasingly used for in situ groundwater and soil remediation because of its high redox activity and specific characteristics of nanoparticles (NPs). Recent applications are often involved in the use of surface-modified nZVI with the stabilizer that can enhance mobility of nZVI while travelling through the underground aquifer. However, the ultimate fate of iron NPs under- or above-ground aquifer and associated risks of exposure and toxicity to environmental life remain poorly understood at present. The objective of the study is to understand modes of toxic action of different iron NPs by comparing their lethal and sublethal effect(s) in medaka (Oryzias latipes). We have treated medaka larvae with thoroughly characterized solutions containing nZVI (uncoated), carboxymethyl cellulose sodium (CMC)-coated nZVI, nanoscale iron oxides (nFe3O4) and ferrous (Fe2+) ion at 0.5 - 100 mg/L for 7 days aqueous exposure. TEM images indicated that uncoated nZVI and nFe3O4 tended to aggregate, but CMC-nZVI did not. Dissolve oxygen suddenly dropped to 0 mg/L for >180 min and total reactive oxygen species (ROS) were elevated after the addition of CMC-nZVI and nZVI (100 mg/L). Fe2+ and Fe3+ were major species in CMC-nZVI, but at low concentration in the nZVI solution during 24 hr’s monitoring. In the meantime, the acute toxicity were in the order of Fe2+ ＞ CMC-nZVI ＞ nZVI ＞ nFe3O4 at high exposure concentrations (50 and 100 mg/L). At low exposure concentrations (0.5 and 5 mg/L), nFe3O4 and Fe2+ significantly increased CAT, GR activities and intracellular ROS levels, but decreased SOD activity. CMC-nZVI and nZVI only altered CAT activity. Based on histopathological analyses, treated groups (> 25 mg/L of CMC-nZVI, nZVI, nFe3O4 and Fe2+) led to various degrees of accumulation of iron particles in the fish gill and intestine tissues. Intestine wall and intestinal villi were damaged at some treated groups (> 25 mg/L of CMC-nZVI and nZVI). In this study, we observed that the use of stabilizer on nZVI and its reaction products (nFe3O4 and Fe2+) may increase hazardous risk of nZVI to the aquatic ecosystem.
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Chang, YU-Chia, and 張祐嘉. "Studies on the Pollution Treatment of Nitro-base Explosive with Nanoscale Zero-valent IRON." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/70125028247277748304.
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碩士朝陽科技大學
應用化學系
105
The fire explosive compositions may be left in camps or in the training field due to improper handling of military munitions. This may result the pollution in water or soil to affect human health. Facing the potentially explosive pollution problems in the camp, how effective processing explosives-contaminated water and soil, become a important research topic This study includes the simulation of using zero-valent iron for ground water which was contaminated by explosives, and treatment effectiveness under various operating conditions. A series of treatment of explosive RDX by different concentrations , acid concntrations, temperature and zero-Valent iron particle sizes were resulted acidic concontreation, higher temperature, high concentration Zero-Valent iron or small grain size helping RDX degradation reaction. Summarize the results in this research, we know that zero-valent iron can treat fire explosives RDX efficiently. Degradation of this experimental results can be used in real game explosives and pollution control reference in the future.
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Sheu, Yih-Terng, and 許藝騰. "Treatment of chromium-containing wastewater from an electroplating plant using nanoscale zero-valent iron (nZVI)." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/31956828840958678194.
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碩士國立暨南國際大學
土木工程學系
99
In this study, nanoscale zero-valent iron (nZVI) was applied to treat chromium-containing wastewater collected from an electroplating plant. Batch experiments were conducted to evaluate the efficiency of chromium removal under closed and semi-closed conditions. The wastewater used in this study contained approximately 1,400 mg/L of total chromium (total Cr), including 1,000 mg/L of hexavalent chromium (Cr6+). Results of the closed system experiments show that the removal efficiencies of total Cr by 0.1, 0.5, 1, 2 and 5 g/L of nZVI were 7.8, 30.3, 57.1, 100, and 100%, respectively, during 24 hours of reaction. The removal efficiency of total Cr reached 100% rapidly with the addition of 5 g/L nZVI during a 5-minute reaction. Trivalent chromium (Cr3+) was detected in the aqueous phase during the removal of Cr6+. X-ray photoelectron spectroscopy (XPS) analysis confirmed that Cr3+ was present on the surface of nZVI. This indicates that nZVI can reduce Cr6+ effectively, and then adsorbs Cr3+ onto its surface. The total Cr removal capacity of nZVI was approximately 0.7-0.8 g total Cr/g nZVI. In addition, nZVI was capable of removing anions including NO3-、NO2-、PO43- and SO42-. Results also show that the removal rate of total Cr by nZVI increased with increased temperature. The adsorption of Cr by nZVI fits the pseudo-second-order kinetic model and the Freundlich isotherm. The results of the semi-closed system experiments show that the removal efficiency of total Cr was decreased due to oxygen penetration. The adsorbed Cr3+ can be recovered from the produced iron-chromium sludge by hydrochloric acid pickling, and then the residual spent iron particles can be collected to reproduce nZVI for further applications. Experimental results reveal that the removal efficiency of total Cr by the reproduced nZVI was similar to that of directly synthesized nZVI. The results of this study show that the application of nZVI can treat chromium-containing wastewater rapidly and effectively. In addition, the reproduced nZVI also has the potential to be reused in the treatment process.
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Shen, Chang-Hung, and 沈長鴻. "Development of a recycling-based chromium wastewater treatment system using nanoscale zero-valent iron (nZVI)." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/04410745195997891993.
Full textAbstract:
碩士國立暨南國際大學
土木工程學系
102
Electroplating wastewater containing heavy metals is usually a majority of the genus such as chromium, nickel, copper, zinc, etc., if not handled directly discharged into the environment will cause harm. Heavy metals commonly used method of waste handling chemical coagulation, electro coagulation, ion exchange, electrolysis, evaporation and adsorption, etc. In recent years, some new methods, such as nanotubes, nano photocatalyst and nanoscale zero-valent iron, etc., have also been used for the adsorption of heavy metals on the reduction or handling. Nanoscale zero-valent iron with a high specific surface area, high reactivity and reducing other characteristics of heavy metals in water has a fairly good deal of success. In this study, laboratory-synthesized nanoscale zero-valent iron (nZVI). First experiment to use batch processing of liquid waste containing chromium, by nanoscale zero valent iron large amount of surface area and strong reduction of the target pollutant adsorption and reduction of conduct, in addition to the target contaminants can be removed from the waste, but also to change its oxidation state, so toxicity greatly reduced. Follow-use Jar test to simulate real iron-chromium sludge treatment plant applications and conduct arising from recycling. Chromium used in this study, which the department of wastewater in batch experiments total chromium content of about 1300 mg/L, which hexavalent chromium content of 880 mg/L. Experiments carried out in batches, in the headspace with nitrogen and air were the case, investigate the oxygen in the air and a dose of nanoscale zero-valent iron removal efficiency for wastewater containing chromium, after the experimental results show , between the headspace with nitrogen and air headspace seems not much difference. And then use Jar test to handle chromium electroplating wastewater plants, of which the total chromium content of about 540 mg/L, which hexavalent chromium content of 400 mg/L. The use of different doses of nanoscale zero-valent iron experiments were carried out under different is that the stirring speed, experimental results show that nanoscale zero-valent iron in adding 10 g/L and 15 g/L down within 4 hours of reaction time, can be in the chrome plating waste removal. At different speeds among, 250 rpm is the most capable to remove chromium. Finally then precipitated iron-chromium sludge collected at the bottom of the reactor, using 1 N hydrochloric acid 100mL the reaction was concentrated in experiment 60 minutes, experimental results show that adding 15g and 20g of iron-chromium sludge has high chromium ions concentrate. However, according to the proportion of the added calculated to add 10g of iron-chromium sludge was better.
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Che, Choi-hong, and 謝彩虹. "Preparation of Nanoscale Zero-Valent Iron Suspension and Its Transport Model in Saturated Soil Layer." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/52570937793649047962.
Full textAbstract:
碩士國立臺灣大學
環境工程學研究所
96
Direct injection zero valent iron method has been widely used for treating chlorinated hydrocarbon contaminated groundwater aquifers. However, the efficiency decreases and the cost rises due to the poor spreading ability of iron particles in the subsurface environment. Therefore, if we can enhance the spreading ability of iron in porous media by adding surface modifier we may increase the applicability of iron particles. We used different stabilizing to produce nanoscale iron suspension by means of batch experiments. Also we evaluated the performance of the stabilizing dispersants. It was found that PAA can get the most stable suspension when the final concentration of PAA and total iron were both 5000 ppm. About 90% of the nano-particles remained in suspension for 28 days. The average particle sizes was 87 nm determined by ZetaSizer. Particle sizes were all found to be around 200 nm and the particles seemed to be wrapped in high oxide-containing stabilizing dispersants under the examination with SEM-EDS. Percolation rates of nanoscale iron particles through the soil was tested using column experiments. The percolation results for soil columns with depth of 10 cm, 20 cm and 30 cm were 75.6%, 61%, and 41%, respectively; and the decay coefficient (κ) of the suspended nanoscale iron particles per unit distance was 0.01 cm-1 A transport model of NZVI in saturated soil layer was constructed. The pore structure in soil layer was characterized by the constructed tube model. The absorbing situation of particle of soil surface was determined by trajectory analysis in the constricted tube. The modeling analyses and experimental results indicate that the prediction has over estimated the breakthrough concentration . Simulation value relatively conforms the experimental value when adjusting the diameter of the particles and considering Brownian forces.
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(8774588), Spencer A. Fehlberg. "Decomposition of ammonium perchlorate encapsulated nanoscale and micron-scale catalyst particles." Thesis, 2020.
Find full textAbstract:
Iron oxide is the most common catalyst in solid rocket propellant. We have previously demonstrated increased performance of propellant by encapsulating iron oxide particles within ammonium perchlorate (AP), but only nanoscale particles were used, and encapsulation was only accomplished in fine AP (~20 microns in diameter). In this study, we extended the size of particle inclusions to micron-scale within the AP particles as well the particle sizes of the AP-encapsulated catalyst particles (100s of microns) using fractional crystallization techniques with the AP-encapsulated particles as nucleation sites for precipitation. Here we report catalyst particle inclusions of micron-scale, as well as nanoscale, within AP and present characterization of this encapsulation. Encapsulating micron-sized particles and growing these composite particles could pave the way for numerous possible applications. A study of the thermal degradation of these AP-encapsulated particles compared against a standard mixture of iron oxide and AP showed that AP-encapsulated micron-scale catalyst particles exhibited similar behavior to AP-encapsulated nanoscale particles. Using computed tomography, we found that catalyst particles were dispersed throughout the interior of coarse AP-encapsulated micron-scale catalyst particles and decomposition was induced within these particles around catalyst-rich regions.
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Deng, Si Wei, and 鄧思薇. "Efficiency and Reaction Mechanism of Oxytetracycline in Water Using Montmorillonite-Supported Nanoscale Zero-Valent Iron Composites." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/nr923n.
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陳輝霖. "A Study of Printed Circuit Board Wastewater via Electrical Coagulation System Treatment by Nanoscale Iron Particles." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/84039656469961161805.
Full textAbstract:
碩士國立臺灣師範大學
圖文傳播學系
93
Many kinds of chemical and special raw material are used in the process of manufacturing printed circuit board. It produces a large amount of harmful waste liquid and pollutants which can derive to a severe environmental issue. Nowadays the problem of high content of COD (Chemical Oxygen Demand) still can not be solved effectively in the wastewater process system . The electrical coagulation system has some advantages such as small land occupation, simple operation, low operation cost and high efficiency. In addition, the nanoscale iron particles have some features such as high volumes of surface area and mass, quick response speed and high efficiency. Due to various kinds of superior characteristics of nanoscale iron particles, this research employ the nanoscale iron particles in developing electrical coagulation system, and evaluated every factor in electrical coagulation system which includes PH index, power voltage and hydraulic retention times (HRT). This research is trying to analyze the best operating condition and procedure for treatment efficiency. The experiments in this study consisted of three phases: The first part, the experiment of leading the way for the electrical coagulation. The second part, the experiment of electrical coagulation for not adding the nanoscale iron particles. The third part, the experiment of electrical coagulation for adding the nanoscale iron particles.The study result shows that the best treatment efficiency was adding nanoscale iron particles, while PH=2 with applied power voltage 100V within 5 minutes HRT. Based on this operation condition and follow the procedure, up to 95.28% of COD can be cleaned out. It was verified by the experiment that the method of adding nanoscale iron particles in electrical coagulation system during the treatment of printed circuit board wastewater can eliminate and reduce the COD waste water in printing circuit board effectively.
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Su, Chih-Hsiang, and 蘇志翔. "Toxicity assessments of stabilized nanoscale zero-valent iron and its oxidation products in medaka (Oryzias latipes) larvae." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/58874001583916324993.
Full textAbstract:
碩士臺灣大學
農業化學研究所
98
Iron-based nanotechnologies are increasingly used for environmental remediation; however, the aqueous fate and toxicologic impacts of engineered iron nanoparticles (NPs) on the aquatic ecosystem remain poorly understood. We treated larvae of medaka fish (Oryzias latipes) with 1-100 mg/L doses of thoroughly characterized solutions containing carboxymethyl cellulose (CMC)-stabilized nanoscale zerovalent iron (nZVI), aged nanoscale iron oxides (nFe-oxides) or ferrous ion (Fe[II]) for 12-14 days’ aqueous exposure to assess the causal toxic effect(s) of iron NPs on the fish. Dosing solutions were daily renewed and temporal changes of the particle size, pH and dissolved oxygen (DO) and reactive oxygen species (ROS) of the dosing solutions were monitored. Results show that the particle size of nZVI was remained around 50 nm and pH of the dosing solutions was consistent between 6-8 within 24 hr. We found that approximately 50% of nZVI was dissociated to Fe(II) ions in 10 mins and Fe(II) ions was then immediately oxidized to Fe(III) oxidizes. Due to rapid oxidation reaction of nZVI in water, DO of nZVI solution (100 mg/L) was thus down to zero for 50 minutes, while DO of nZVI solution (1-25 mg/L) stayed at 2-3 mg/L for an hour. In the meantime, high nZVI (100 mg/L) resulted in acute toxicity (65% mortality) of medaka larvae after a 7-day exposure; however, low larval mortality (<15%) was found from nZVI exposure (1-25 mg/L). Compared to nZVI, Fe(II) ion (50 mg/L) resulted 55% larval mortality, while 25 mg/L Fe(II) only caused 2.5 % mortality to medaka larvae after 7-days exposure. Based on histopathological analyses, fish intestine from the treated groups (>25 mg/L nZVI) accumulated high amount of ferrous iron and their intestine wall was significantly thinner than the control fish. We discuss the modes of acute toxic action of CMC-nZVI and chronic toxic effects in terms of ROS, hypoxia and Fe(II) toxicity.