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Potencijal primene stabilisanog i „zelenom“ sintezom produkovanog nano gvožđa (0) za remedijaciju sedimenta kontaminiranog metalima / Potential application of stabilized and "green" produced nano zero -valent iron for remediation of sediment contaminated with metalsSlijepčević Nataša 02 October 2020 (has links)
<p>Ekološki problem svetskih razmera predstavlja zagađenost sedimenta teškim metalima, usled negativnih ekoloških efekata metala na životnu sredinu. Mnoge zemlje i regioni, kao i naša zemlja suočavaju se sa ovom problematikom, koja je vrlo rasprostranjena usled sve brže urbanizacije i industrijalizacije, a sa sve većom nebrigom usled ispuštanja otpadnih voda bez prethodnog prečišćavanja u vodotokove. Prilikom promene uslova vodenog ekosistema, može doći do izluživanja metala i štetnih efekata na životnu sredinu kao i na zdravlje ljudi. Stoga je remedijacija sedimenata zagađenih metalima ključna aktivnost u okviru procesa potpune sanacije vodenog ekosistema, a ekonomične, efikasne i ekološki prihvatljive tehnike remedijacije su hitno potrebne i rado primenljive u tretmanu na velikoj skali. Pre primene remedijacione tehnike na velikoj skali, neophodna su ispitivanja pri laboratorijskim uslovima i pilot skali. Na kraju svakog uspešnog laboratorijskog ispitivanja nalaze se pilot istraživanja. Pomoću njih se dobija p ravi odgovor u smislu izbora optimalne tehnologije imajući u vidu investicione i operativne troškove,<br />postignuti rezultat i krajnje ciljeve u pogledu upravljanja postrojenjem i otpadom. U ovom radu ispitan je potencijal primene stabilisanog i zelenom sinte zom produkovanog nano Fe(0) zaremedijaciju sedimenta zagađenog teškim metalima. Kao remedijaciona tehnika odabrana je stabilizacija/solidifikacija, koja podrazumeva dodavanje agenasa za imobilizaciju metala u sedimentu sprečavajući time potencijalni rizik od izluživanja metala u životnu sredinu. Konvencionalni materijali poput letećeg pepela, cementa, gline se već odavno koriste u ovu svrhu. Kako u današnje vreme raste potražnja za novim, lako dostupnim agensima za stabilizaciju<br />sedimenta, došlo se na ideju o primeni nanomaterijala na bazi gvožđa, tj. nano Fe(0) stabilisanog nativnom glinom i produkovanog redukcijom pomoću organskih molekula prirodno prisutnih u ekstraktu lišća hrasta i crnog duda. Nanomaterijali su sintetisani i karakterisani različitim metodama i tehnikama. U nastavaku, u cilju efikasnosti njihove primene za stabilizaciju sedimenta, sprovedeni su ekstrakcioni i dinamički laboratorijski testovi izluživanja. Odabrane su smeše sedimenta i nanomaterijala koje su pokazale najbolju efikasnost tr etmana. Nakon toga se ispitivanje nastavilo na pilot skali, gde se pratilo ponašanje nanomaterijala u zavisnosti od konvencionalnih materijala koji su već u literaturi dokumentovani kao efikasni imobilizacioni agensi. Dodatna potvrda uspešnosti tretmana data je analizom i karakterizacijom s/s smeša nakon pilot ispitivanja Na osnovu dobijenih rezultata proces se uspešno pokazao pri laboratorijskim uslovima, a takođe i prilikom pilot tretmana, odnosno nakon pilot tretmana nije došlo do povećanih koncentracija izluživanja metala iz s/s smeša, kao ni degradacije smeša nakon procesa ovlaživanja tokom šest meseci. Na osnovu toga, ovako tertirani sediment se može bezbedno odlagati na deponije, ili pak iskoristiti za „kontrolisanu“ upotrebu, izgradnju puteva,kamenoloma, pomoćnih objekata i slično. Rezultati su doprineli u cilju trajnijeg rešavanja pitanja odlaganja zagađenog (izmuljenog) rečnog sedimenta, pri čemu se u procesu stabilizacije/solidifikacije dobijaju proizvodi sa dodatom vrednošću neumanjenog kvaliteta .Nanomaterijali sintetisani u ovom radu na bazi ekstrakta lišća biljaka doprinose kako očuvanju životne sredine, tako i ekonomičnosti primene remedijacione tehnike. Zahvaljujući velikoj specifičnoj površini, malim dimenzijama čestica i velikom kapacitetu za imobilizaciju teških<br />metala predstavljaju efikasnu alternativu komercijalno dostupnim materijalima, što ih čini veoma atraktivnim i obećavajućim u budućnosti pri tretmanu rečnog sedimenta zagađenog teškim metalima.</p> / <p>The pollution of sediment by heavy metals represents a large environmental problem all<br />over the world. A lot of countries in the region as well as our country deal with this problem, which is widespread because of the fast urbanization and industrialization. There is more and more carelessness about wastewater discharge into water flows without previous purification. When the conditions of the aquatic ecosystem change, metal leaching and harmful effects on the environment and human health can occur. Therefore, remediation of metal-contaminated sediments is crucial activity in the process of the complete ecosystem remediation. Cost effective, efficient and environmentally friendly remediation techniques are urgently needed and readily applicable in large-scale treatment. Before applying remediation techniques on the largescale, both laboratory and pilot tests are necessary. There are pilot studies at the end of each successful laboratory test. Those studies provide the right answer in terms of choosing the optimal technology, taking into account the investment and operating costs, the achieved resultand the ultimate goals in terms of plant and waste management. In this study, the application<br />potential of stabilized and green - synthesized nano Fe(0) for the remediation of heavy metal -contaminated sediment was investigated. Stabilization / solidification technique was chosen as remediation technique which involves the addition of metal immobilizing agents in the sediment thus preventing the potential risk of metal leaching into the environment. Conventional materials such as fly ash, cement and clay have long been used for this purpose. Nowadays there is need for new, easily accessible agents for the sediment stabilization. Therefore it came up with the idea of using iron-based nanomaterials, ie. nano Fe(0) stabilized by native cla y and produced by reduction using organic molecules naturally present in oak and black mulberry leaf extract. Nanomaterials have been synthesized and characterized by different methods and techniques. In order to be effective in their application for sediment stabilization, extraction and dynamic laboratory leaching tests were performed. Mixtures of sediment and nanomaterials were selected that showed the best treatment efficiency. After that, the examination was continued on a pilot scale, where the behavior of nanomaterials was monitored, depending on conventional materials which have already been documented in the literature as effective immobilizing agents.Additional confirmation of treatment success was given by analysis and characterization of s / s mixtures after pilot testing. According to obtained results, the process was successfully demonstrated under laboratory conditions, and also during the pilot treatment. After the pilot treatment there were no increased concentrations of metal leaching from s/s mixtures, nor mixture degradation after the wetting process for six months. Based on that, the sediment treated in this way can be safely disposed of in landfills, or used for "controlled" use, construction of<br />roads, quarries, auxiliary facilities and etc. The results have contributed to the goal of a more permanent solution to the issue of disposal of polluted (slugged) river sediment, whereby in the process of stabilization/solidification, products with added value of undiminished quality are obtained. The nanomaterials synthesized in this paper on the basis of plant leaf extract contribute to both the preservation of the environment and the economy of remediation techniques. Thanks to their large specific surface area, small particle size and large ca pacity for immobilization of heavy metals, they represent an effective alternative to commercially available materials. It makes them very attractive and promising in the future in the treatment of river sediment contaminated with heavy metals.</p>
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Electrosynthèse assistée par ultrasons de nanoparticules de fer à valence zéro : étude de la croissance de dépôts et de leur dispersion par ondes acoustiques / Ultrasounds assisted electrosynthesis of zero valence iron nanoparticles : study of the deposit growth and dispersion by acoustic wavesIranzo, Audrey 25 November 2016 (has links)
La synthèse de nanoparticules de fer zéro-valent, par le couplage des procédés d'ultrasonication et d'électrodéposition, est étudiée selon deux approches. La première partie de l'étude s'intéresse à l'influence du substrat, utilisé pour l'électrodéposition, sur la croissance des dépôts de fer et sur leur dispersion par ultrasonication. L'énergie interfaciale ainsi que l'énergie d'adhésion du dépôt sur le substrat (Y_(Fe/substrat) et W_(Fe/substrat) respectivement) étant reliées à l'énergie de surface et à la rugosité du substrat, un intérêt particulier a été porté à ces deux propriétés. Ainsi, deux matériaux présentant des énergies de surface différentes, l'or (Au) et le carbone vitreux (VC), ainsi que des rugosités différentes ont été testés. Un développement théorique basé sur les interactions de Van der Waals a permis de démontrer que Y_(Fe/VC)>Y_(Fe/Au) ce qui suggère une meilleure affinité du dépôt de fer avec l'or qu'avec le VC. Cette différence influence la morphologie (croissance 2D sur or et 3D sur le VC) mais aussi l'adhésion des dépôts. En effet, les expériences réalisées pour étudier l'effet des ultrasons sur le dépôt de fer révèlent une dispersion du dépôt progressive et complète pour le cas du VC alors qu'aucun détachement du dépôt n'est obtenu en utilisant l'or. La seconde partie de l'étude est consacrée à la synthèse de nanoparticules de fer par une nouvelle approche : l'électrodéposition de dépôts de fer ramifiés est étudiée dans une cellule de Hele-Shaw intégrant un élément vibrant (diaphragme piézoélectrique) permettant à la fois la formation de dépôts de fer et leur fragmentation. Les expériences menées révèlent que les bulles d'hydrogène, formées lors de la co-réduction des protons libres durant l'électrodéposition du fer, influencent fortement le processus de fragmentation. En utilisant des hautes fréquences et amplitudes de vibration du PZT, les bulles d'hydrogène oscillent avec des déformations de surface. Celles-ci génèrent des vitesses d'interface suffisamment hautes (˜ 4 m/s) pour permettre aux bulles de fragmenter des dépôts ramifiés en particules de fer, de tailles comprises entre 1 µm et 100 nm, et présentant une grande surface spécifique due à leur morphologie dendritique. Cette deuxième partie de l'étude permet d'ouvrir la voie à une nouvelle technologie de fabrication des nanoparticules. / This study concerns the coupling of the ultrasounds with the electrodeposition process for the synthesis of zero-valent iron nanoparticles; it is structured in two sections. The first focuses on the electrode substrate used for the iron electrodeposition and aims to determine its influence on both the deposit growth and its dispersion by ultrasonication. The interfacial and the adhesion energies of the deposit on the substrate (Y_(Fe/substrate) and W_(Fe/substrate) respectively) being related to the surface energy and the roughness of the substrate, a particular focus is put on the influence of these two properties. Thus, two materials of different surface energies, gold (Au) and vitreous carbon (VC), as well as various roughnesses, are tested. Considering only the Van der Waals interactions, a theoretical development has enabled to determine that Y_(Fe/VC)>Y_(Fe/Au) which suggests a better affinity of the iron deposit with the gold than with the VC substrate. This difference impacts the deposit morphology (2D growth on the gold and 3D growth on the VC substrate) but also the deposit adhesion. Indeed, experiments performed to study the effect of ultrasounds on the iron electrodeposit reveal its progressive and complete dispersion for the vitreous carbon case while no dispersion (no removal of the deposit from the electrode) is obtained with the gold substrate. The second section of the present study deals with the synthesis of iron nanoparticles; to this end, the electrodeposition of branched deposits has been investigated in a Hele-Shaw cell integrating a vibrating element (piezoelectric diaphragm), expected to allow both the deposit formation and its fragmentation. Experiments reveal that the hydrogen bubbles, formed by the co-reduction of free protons during the iron electrodeposition, strongly influence the fragmentation process. Using high vibration frequencies and high amplitudes, the bubbles oscillate with surface deformations, inducing interface velocity sufficiently high (˜ 4 m/s) to allow the fragmentation of the deposit into particles of sizes ranging between 1 µm and 100 nm and showing a high specific surface due to their dendritic morphology. Thus this work opens the way for a new particles manufacturing technology.
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S?ntese e caracteriza??o do comp?sito ferro zero-valente nanoparticulado/carv?o ativado granulado (nFZV-CAG) e sua aplica??o para remo??o do f?rmaco nimesulida pelos processos adsor??o/redu??o e ozoniza??o catal?tica heterog?neaOliveira, Fernanda Gandra de 13 September 2016 (has links)
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Previous issue date: 2016 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Funda??o de Amparo ? Pesquisa do Estado de Minas Gerais (FAPEMIG) / O comp?sito nFZV-CAG foi empregado para a ozoniza??o catal?tica heterog?nea da NMS em
meio aquoso. O oz?nio foi gerado por uma central geradora de oz?nio IPABRAS, alimentada
com ar. Foram avaliados diferentes processos catal?ticos como O3, CAG, O3-CAG, O3-nFZV-
CAG, e a varia??o da concentra??o das nFZV para remo??o da NMS. Os resultados mostraram
que a combina??o do O3-nFZV-CAG foi muito eficiente levando ? mineraliza??o de
aproximadamente 70% da NMS em 120 min de rea??o. Tal efici?ncia pode estar atribu?da ao
processo de eletr?lise, em que o Fe0
origina Fe2+
levando ? produ??o do radical hidroxila que ?
altamente oxidante, levando a destrui??o do contaminante. As rea??es seguiram a cin?tica
pseudo-primeira ordem para remo??o do f?rmaco. Ap?s realizada a coleta as amostras foram
submetidas a an?lise qu?mica, empregando-se as t?cnicas de espectrofotometria de UV-Vis,
cromatografia l?quida de alta efici?ncia (CLAE) e a determina??o da demanda qu?mica de oxig?nio
(DQO) tamb?m foi realizada. / As nanopart?culas de FZV imobilizadas sobre a superf?cie do carv?o ativado (nFZV-CAG)
foram sintetizadas e caracterizadas para remo??o do f?rmaco Nimesulida (NMS) em sistemas
aquosos. Os estudos foram realizados em bateladas com agita??o de 250 rpm durante 120
minutos, onde foram avaliadas a efici?ncia, concentra??o (20, 25 e 30% do comp?sito) e
diferentes dosagens (0,1 a 10g) de nFZV-CAG. Os resultados mostraram que a dosagem de 10
g de 20%nFZV-CAG removeu cerca de 80% da NMS 50 mg L-1
em apenas 30 minutos de
rea??o, e atingindo 100% em 120 minutos. Foi observada ainda uma remo??o de 80% da DQO
ao final da rea??o. As velocidades de rea??o aumentaram na medida em que foram aumentadas
as dosagens do comp?sito, o que seria esperado. Por?m, com o aumento da concentra??o (%)
de nFZV n?o houve aumento na velocidade das rea??es. As rea??es seguiram uma cin?tica de
pseudo-primeira ordem em rela??o ? remo??o da NMS. Ap?s realizada a coleta, as amostras
foram submetidas a an?lise qu?mica, empregando-se as t?cnicas de espectrofotometria de UV-
VIS, cromatografia l?quida de alta efici?ncia (CLAE) e a determina??o da demanda qu?mica de
oxig?nio (DQO) tamb?m foi realizada. Para caracteriza??o do comp?sito foram empregadas as
t?cnicas Microscopia Eletr?nica de Varredura acoplada ? Espectrometria de Energia Dispersiva
de Raios-X (MEV-EDS), que mostraram claramente a presen?a da nanopart?culas sobre a
superf?cie do carv?o, e analise de superf?cie do nFZV-CAG e do CAG tamb?m foram
realizadas. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2016. / The FZV nanoparticles immobilized onto the surface of the activated charcoal (nFZV-CAG)
were synthesized and characterized for the removal of the pharmaceutical Nimesulide (NMS)
in aqueous systems. The studies were performed in batch mode with stirring speeds of 250 rpm
during 120 minutes, so that it was possible to evaluate efficiency, concentration (20, 25 and
30% of the composite) and different dosages (0,1 to 10g) of nFZV-CAG. The results showed
that the dosage of 10g of 20%nFZV-CAG removed approximately 80% of NMS 50 mg L-1
in
just 30 minutes of reaction, and reaching 100% in 120 minutes. It was still observed a removal
of 80% of the COD (Chemical Oxygen Demand) at the end of the reaction. The reaction rates
increased with the dosage of the composite, which was expected. Though, increasing the
concentration (%) of nFZV did not result in higher reaction rates. The reactions followed a
pseudo-first order kinetics for the removal of NMS. After the samples were collected, they were
submitted to chemical analysis, employing the techniques of UV-VIS spectroscopy, high
performance liquid chromatography (HPLC) and chemical oxygen demand (COD). In order to
characterize the composite, the following techniques were used: Scanning Electron Microscopy
(SEM) coupled with Energy Dispersive x-Ray spectroscopy (EDS), which showed clearly the
presence of nanoparticles onto the charcoal surface. Analysis of the surface of nFZV-CAG were
also performed. / The composite nFZV-CAG was used for the catalytic ozonation of NMS in aqueous media. The
ozone was generated by an ozone generator IPABRAS, fuelled with air. Different catalytic
processes were evaluated such as O3, CAG, O3-CAG, O3-nFZV-CAG, and the variation of the
nFZV concentration for the removal of NMS. The results showed that the combination of O3-
nFZV-CAG was very efficient, leading to the mineralization of approximately 70% of NMS in
120 minutes of reaction. Such efficiency can be attributed to the electrolysis process, in which
the Fe0
generates Fe2+
which generates hydroxyl radicals that are highly oxidant, leading to the
destruction of the contaminant. The reactions followed the pseudo-first order kinetics for the
removal of the pharmaceutical. After the samples were collected, they were submitted to
chemical analysis such as, UV-VIS spectroscopy, high performance liquid chromatography
(HPLC) and chemical oxygen demand (COD).
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