Orientador: Wilson de Figueiredo Jardim / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-05T13:56:31Z (GMT). No. of bitstreams: 1 Arruda_TatianaLangbeckde_M.pdf: 1545576 bytes, checksum: 2e2b76b3f7f23e5e8b1087d0e9dc7912 (MD5) Previous issue date: 2005 / Mestrado / Quimica Analitica / Mestre em Química

Orientador: Wilson de Figueiredo Jardim / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-13T18:50:44Z (GMT). No. of bitstreams: 1 Franco_DeboraVilela_D.pdf: 6112505 bytes, checksum: 9ffd8531fa2a0322c7b7d08e90de70fa (MD5) Previous issue date: 2008 / Resumo: A redução química do cromo hexavalente, Cr(VI), presente em solo e água subterrânea contaminados, foi investigada empregando-se diferentes agentes redutores (batelada e semi-batelada) para avaliar a extensão da redução do Cr(VI) e da imobilização (precipitação) do cromo trivalente, Cr(III). O estudo comparativo envolvendo o uso de diferentes agentes redutores evidenciou que as espécies Fe(II) e FZVcol (nanopartículas estabilizadas com carboximetilcelulose) apresentaram os resultados mais promissores para a remoção do Cr(VI), visto que houve uma redução quantitativa desta espécie com sua concomitante imobilização. A aplicação do Fe(II) e FZVcol nas razões molares 1[Cr(VI)]:20[Fe(II)] e 1[Cr(VI)]:4[FZVcol] resultou na conversão redox superior a 98% e na imobilização das frações de Cr(VI) lábil e trocável. Foi verificado para o Fe(II), que o aumento da velocidade do fluxo volumétrico (G) resulta na diminuição do número de volume de poro para o tratamento do solo e da quantidade de Cr(VI) residual. O estudo hidrodinâmico teórico da coluna recheada com solo (meio poroso) permitiu mensurar o grau de dispersão do redutor na coluna frente ao modelo pistonado de escoamento em função de G mediante o cálculo do coeficiente de dispersão mássica volumétrico (kDV), o qual foi calculado a partir da modelagem da curva de saturação experimental. Foi verificado em todos os casos que a cinética do processo redox Cr(VI)/Cr(III) segue uma lei empírica de velocidade de pseudo-primeira ordem. A complexidade cinética do processo redox foi evidenciada pela dependência da constante de velocidade global de pseudo-primeira ordem (k*) com o tempo de reação, G e a concentração inicial do redutor. Um modelo cinético fenomenológico foi proposto para se obter uma expressão representativa de k* nas diferentes situações experimentais investigadas, bem como nos casos limites previstos. Um esquema reacional global foi proposto para representar os diferentes processos elementares envolvendo as espécies Cr(VI) e Cr(III) na matriz porosa (solo/água subterrânea). Um ensaio de tratamento em escala piloto foi realizado in situ tendo-se como balizadora as condições experimentais mais promissoras obtidas nos estudos realizados em escala laboratorial / Abstract: Chemical reduction of the hexavalent chromium, Cr(VI), present in contaminated soil and groundwater was investigated using several different reductants (batch and semi-batch) in order to evaluate the extension of Cr(VI) reduction and the immobilization (precipitation) of trivalent chromium, Cr(III). A comparative study concerning the use of different reductants revealed that Fe(II) and ZVIcol (nanoparticles stabilized with carboximethylcellulose) present the most promising findings for the Cr(VI) removal, since it was found that a quantitative reduction of this specie is accompanied by its immobilization. Application of Fe(II) and ZVIcol using the 1[Cr(VI)]:20[Fe(II)] and 1[Cr(VI)]:4[ZVIcol] molar ratios resulted in a redox conversion degree higher than 98% and in the immobilization of the labile and the exchangeable Cr(VI) fractions. It was verified for Fe(II) that increasing the volumetric flow rate (G) both the pore volume necessary for the redox treatment and the residual Cr(VI) decrease. The theoretical hydrodynamic study concerning the packed column reactor containing soil (porous medium) permitted to evaluate the reductant dispersion degree inside the column in relation to the plug-flow model as functions of G by measuring the volumetric mass dispersion coefficient (kVD), which was calculated from simulation of the experimental saturation curve. In all cases, it was found the kinetics of the Cr(VI)/Cr(III) redox process follows a pseudo-first order rate law. The complexicity concerning the kinetic process was evidenced by the dependence of the overall pseudo-first order kinetic rate constant (k*) on reaction time, G and the initial concentration of the reductant. A phenomenological kinetic model was proposed in order to obtain a relation capable to represent k* for the different experimental conditions investigated, as well for the possible limit cases. An overall reaction scheme was proposed in order to describe the different elementary processes concerning the Cr(VI) and Cr(III) species, which take place inside the porous soil matrix (soil/groundwater). A pilot scale test was carried out in situ taking into account the best experimental scenario obtained in laboratory. / Doutorado / Quimica Analitica / Doutor em Ciencias Quimicas

La présence excessive des phosphates est la cause de l’apparition du problème d’eutrophisation dans les eaux douces et responsable de la détérioration des écosystèmes aquatiques. Différents procédés de traitement des eaux (biologique, physico-chimique) permettent l’élimination des phosphates. L’objectif global de cette thèse est l’étude des mécanismes physico chimiques associés à la rétention des phosphates par sorption sur des produits d’oxydation de la limaille de fer micrométrique et le développement du procédé correspondant. Le choix de ce matériau réside dans sa disponibilité, son faible coût et l’absence de toxicité dans les conditions mises en oeuvre. Afin de pouvoir par la suite proposer un système de traitement opérationnel, dans un premier temps des séries d’expériences en batch ont été menées pour évaluer l’efficacité de la limaille de fer et ces sous-produits synthétisés pour l’élimination des phosphates. L’influence des conditions expérimentales (vieillissement ou phase de pré-conditionnement, concentrations en oxygène dissous, en nitrates, sulfates, matière organique, pH initial, force ionique, vitesse d’agitation) a été évaluée. En parallèle des caractérisations physico chimiques des solides ont été menées dans le but de déterminer la nature et les caractéristiques des sous-produits synthétisés. Dans un second temps, des études en réacteur continu ont été réalisées dans une démarche de complexité croissante pour comprendre le fonctionnement des colonnes garnies de sable/limaille de fer. Les sous-produits synthétisés et relargués en solution en conditions contrôlées (teneur en oxygène dissous ; vieillissement de 40h et 6j) ont montré une plus faible capacité de piégeage pour l’élimination des phosphates (2,3 à 3,8 mgP/gFe) en comparaison avec la capacité retenue par la totalité du système Fe0/sous-produits, dont les capacités ont pu atteindre 35 mgP/gFe. La durée de l’oxydation avant contact avec les phosphates (vieillissement) a une influence remarquable sur l’efficacité de la limaille de fer. Au-delà de 24h, plus le temps de vieillissement est grand, plus l’efficacité des sous-produits diminue, ce qui est expliqué par l’augmentation de la cristallinité des sous-produits de la limaille de fer, ces derniers étant moins réactifs que les formes amorphes. Cependant, une phase de pré-conditionnement d’une durée comprise entre 2h et 24h améliore nettement la rétention des phosphates par la limaille de fer car elle permet la génération d’une couche d’oxydes active en fonction du temps à la surface. Le contact direct de la limaille avec les phosphates, étant donné leur rôle dans la passivation, conduit à limiter la corrosion par la formation d’une couche de passivation compacte à la surface de la limaille de fer. La couche d’oxydes à la surface de la limaille de fer et les sous-produits relargués en solution sont formés par un mélange de lépidocrocite, maghémtite et /ou magnétite et des traces de goethite. Le mécanisme d’élimination des phosphates à la surface des sous-produits se base sur une adsorption spécifique par formation d’un complexe de sphère interne. La distribution des phosphates le long de la colonne a montré une forte dépendance de la concentration en oxygène dissous; elle évolue au cours du temps, elle est hétérogène en début d’expérimentation, puis devient homogène à saturation, avec une capacité maximale de 152 mgP/gFe dans les conditions opératoires appliquées ([P] = 20mg/L, [NaCl] = 0,01M, T° = 22°C, v = 0,12m/h). L’analyse du support solide a confirmé les résultats relatifs à la distribution des phosphates dans les réacteurs et a montré que les phosphates sont majoritairement associés aux fractions amorphes du fer. L’ensemble des résultats obtenus confirme l’intérêt d’utiliser la limaille de fer pour le traitement des phosphates dans les eaux. / The excessive presence of phosphate in water is the cause of the occurrence of the problem of eutrophication in freshwater represented by the deterioration of the aquatic ecosystem. Various water treatment processes allow the removal of phosphate (biological and physico-chemical). The global objective of this thesis is the study of the physico-chemical mechanisms associated with phosphate removal from water using iron byproducts synthesized from the oxidation of micrometric zero valent iron and the development of corresponding process. Zero valent iron was chosen for its availability, low cost, and the absence of toxicity under the conditions applied. In order to subsequently propose an operational processing system, firstly a series of batch experiments were conducted to evaluate the efficacy of iron filings and its by-products synthesized for the elimination of phosphate. The influence of experimental conditions (aging or pre-conditioning phase, dissolved oxygen, nitrates, sulfates, organic matter, initial pH, ionic strength, stirring rate) was studied. In parallel physico-chemical characterizations of the solid were conducted in order to determine the nature and characteristics of synthesized byproducts. Secondly, continuous reactor studies were conducted in an increasingly complex approach in order to understand the behavior and performance of the columns packed with sand/ZVI. The synthesized byproducts flaked into the solution (under controlled conditions of oxygen and aging time 40h, 6g) showed a lower capacity trapping for phosphate removal (2.3 to 3.8 mgP/gFe) compared to phosphate removal capacity of the entire system Fe0/by-products, whose capacity can reach 35 mgP/gFe. The oxidation phase prior to the contact with phosphate (aging time) has a remarkable influence on the efficiency of iron filings. Beyond the preconditioning phase of 24 hours, as aging time increases, the efficiency of the byproducts decreases, which is explained by the increases of the crystallinity of the by-products over time, as being less reactive than amorphous forms. However, the pre-conditioning time between 2h and 24 hours improves clearly the retention of phosphate by ZVI as this phase allows the synthesis of an active oxide layer. Direct contact between the iron fillings and phosphate, taking into account their role in the passivation, leads to a limitation of the corrosion by forming a compact passive layer at the surface of ZVI. The oxide layer at the surface of ZVI and the byproducts flaked off to the solution are formed by a mixture of lepidocrocite, maghemtite and/or magnetite and traces of goethite. The phosphate removal on the surface of the byproducts is based on a specific adsorption by forming an inner sphere complex. The reactivity in the columns showed a strong dependence on the presence and the concentration of oxygen; the decrease in phosphate retention along the column, evolves over time from heterogeneous towards a homogeneous trapping of P with a maximum capacity of 152 mgP/gFe in the applied process conditions ([P] = 20mg / L, [NaCl] = 0.01 M, T = 22 ° C, v = 0.12M / h). The solid support analysis also confirmed the results related to the distribution of phosphate along the reactors, and showed that phosphate are predominantly associated with amorphous iron fractions.The overall results confirm the interest of using iron filings for the treatment of phosphate in water.

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-.

Arsenic and antimony are important trace elements in magmatic-hydrothermal systems, geothermal systems and epithermal deposits, but their partitioning behavior between melt and aqueous fluid is not well understood. The partitioning of arsenic and antimony between aqueous fluid and granitic melt has been studied in the system SiO2-Al2O3-Na2O-K2O-H2O at 800 degree C and 200 MPa. The partition coefficients of As and Sb between aqueous fluid and melt, are 1.4 +- 0.5 and 0.8 +- 0.5, respectively. The partitioning of As is not affected by aluminum saturation index (ASI) or SiO2 content of the melt, or by oxygen fugacity under oxidized conditions (log fO2 > the nickel-nickel oxide buffer, NNO). The partitioning of Sb is independent of and SiO2 content of the melt. However, aluminum saturation index (ASI) does affect Sb partitioning and Sb partition coefficient for peralkaline melt (0.1 +- 0.01) is much smaller than that for metaluminous melts (0.8 +- 0.4) and that for peraluminous melts (1.3 +- 0.7). Thermodynamic calculations show that As(III) is dominant in aqueous fluid at 800 degree C and 200 MPa and XPS analysis of run product glass indicate that only As(III) exists in melt, which confirms the finding that does not affect As partitioning between fluid and melt. XPS analysis of run product glass show that Sb(V) is dominant in melt at oxidized conditions (log fO2 > -10). The peralkaline effect only exhibits on Sb partitioning, not on As partitioning at oxidized conditions, which is consistent with the x-ray photoelectron spectroscopy (XPS) measurements that As(III) and Sb(V) are dominant oxidation states in melt under oxidized conditions, because the peralkaline effect is stronger for pentavalent than trivalent cations. Permeable reactive barriers (PRBs) are an alternative technology to treat mine drainage containing sulfate and heavy metals. Two column experiments were conducted to assess the suitability of an organic carbon (OC) based reactive mixture and an Fe0-bearing organic carbon (FeOC) based reactive mixture, under controlled groundwater flow conditions. The organic carbon (OC) column showed an initial sulfate reduction rate of 0.4 μmol g(oc)-1 d-1 and exhausted its capacity to promote sulfate reduction after 30 pore volumes (PVs), or 9 months of flow. The Fe0-bearing organic carbon (FeOC) column sustained a relative constant sulfate reduction rate of 0.9 μmol g(oc)-1 d-1 for at least 65 PVs (17 months). The microbial enumerations and isotopic measurements indicate that the sulfate reduction was mediated by sulfate reducing bacteria (SRB). The cathodic production of H2 by anaerobic corrosion of Fe probably is the cause of the difference in sulfate reduction rates between the two reactive mixtures. Zero-valent iron can be used to provide an electron donor in sulfate reducing PRBs and Fe0-bearing organic carbon reactive mixture has a potential to improve the performance of organic carbon PRBs. The δ34S values can be used to determine the extent of sulfate reduction, but the fractionation is not consistent between reactive materials. The δ13C values indicate that methanogenesis is occurring in the front part of both columns. Arsenic and antimony in groundwater are great threats to human health. The PRB technology potentially is an efficient and cost-effective approach to remediate organic and inorganic contamination in groundwater. Two column experiments were conducted to assess the rates and capacities of organic carbon (OC) PRB and Fe-bearing organic carbon (FeOC) PRB to remove As and Sb under controlled groundwater flow conditions. The average As removal rate for the OC column was 13 nmole day-1 g-1 (dry weight of organic carbon) and its removal capacity was 11 μmole g-1 (dry weight of organic carbon). The remove rate of the FeOC material was 165 nmole day-1 g-1 (dry weight of organic carbon) and its minimum removal capacity was 105 mole g-1 (dry weight of organic carbon). Antimony removal rate of the OC material decreases from 8.2 to 1.4 nmole day-1 g-1 (dry weight of organic carbon) and its removal capacity is 2.4 μmole g-1 (dry weight of organic carbon). The minimum removal rate of FeOC material is 13 nmole day-1 g-1 (dry weight of organic carbon) and its minimum removal capacity is 8.4 μmole g-1 (dry weight of organic carbon). The As(III) : [As(III)+As(V)] ratio increased from 1% in the influent to 50% at 5.5 cm from the influent end, and to 80% at 15.5 cm from the influent end of the OC column. X-ray absorption near edge spectroscopy (XANES) shows As(III)-sulfide species on solid samples. These results suggest that As(V) is reduced to As(III) both in pore water and precipitate as As sulfides or coprecipitate with iron sulfides. The arsenic reduction rate suggests that As(V) reduction is mediated by bacterial activity in the OC column and that both abiotic reduction and bacterial reduction could be important in FeOC.

Arsenic and antimony are important trace elements in magmatic-hydrothermal systems, geothermal systems and epithermal deposits, but their partitioning behavior between melt and aqueous fluid is not well understood. The partitioning of arsenic and antimony between aqueous fluid and granitic melt has been studied in the system SiO2-Al2O3-Na2O-K2O-H2O at 800 degree C and 200 MPa. The partition coefficients of As and Sb between aqueous fluid and melt, are 1.4 +- 0.5 and 0.8 +- 0.5, respectively. The partitioning of As is not affected by aluminum saturation index (ASI) or SiO2 content of the melt, or by oxygen fugacity under oxidized conditions (log fO2 > the nickel-nickel oxide buffer, NNO). The partitioning of Sb is independent of and SiO2 content of the melt. However, aluminum saturation index (ASI) does affect Sb partitioning and Sb partition coefficient for peralkaline melt (0.1 +- 0.01) is much smaller than that for metaluminous melts (0.8 +- 0.4) and that for peraluminous melts (1.3 +- 0.7). Thermodynamic calculations show that As(III) is dominant in aqueous fluid at 800 degree C and 200 MPa and XPS analysis of run product glass indicate that only As(III) exists in melt, which confirms the finding that does not affect As partitioning between fluid and melt. XPS analysis of run product glass show that Sb(V) is dominant in melt at oxidized conditions (log fO2 > -10). The peralkaline effect only exhibits on Sb partitioning, not on As partitioning at oxidized conditions, which is consistent with the x-ray photoelectron spectroscopy (XPS) measurements that As(III) and Sb(V) are dominant oxidation states in melt under oxidized conditions, because the peralkaline effect is stronger for pentavalent than trivalent cations. Permeable reactive barriers (PRBs) are an alternative technology to treat mine drainage containing sulfate and heavy metals. Two column experiments were conducted to assess the suitability of an organic carbon (OC) based reactive mixture and an Fe0-bearing organic carbon (FeOC) based reactive mixture, under controlled groundwater flow conditions. The organic carbon (OC) column showed an initial sulfate reduction rate of 0.4 μmol g(oc)-1 d-1 and exhausted its capacity to promote sulfate reduction after 30 pore volumes (PVs), or 9 months of flow. The Fe0-bearing organic carbon (FeOC) column sustained a relative constant sulfate reduction rate of 0.9 μmol g(oc)-1 d-1 for at least 65 PVs (17 months). The microbial enumerations and isotopic measurements indicate that the sulfate reduction was mediated by sulfate reducing bacteria (SRB). The cathodic production of H2 by anaerobic corrosion of Fe probably is the cause of the difference in sulfate reduction rates between the two reactive mixtures. Zero-valent iron can be used to provide an electron donor in sulfate reducing PRBs and Fe0-bearing organic carbon reactive mixture has a potential to improve the performance of organic carbon PRBs. The δ34S values can be used to determine the extent of sulfate reduction, but the fractionation is not consistent between reactive materials. The δ13C values indicate that methanogenesis is occurring in the front part of both columns. Arsenic and antimony in groundwater are great threats to human health. The PRB technology potentially is an efficient and cost-effective approach to remediate organic and inorganic contamination in groundwater. Two column experiments were conducted to assess the rates and capacities of organic carbon (OC) PRB and Fe-bearing organic carbon (FeOC) PRB to remove As and Sb under controlled groundwater flow conditions. The average As removal rate for the OC column was 13 nmole day-1 g-1 (dry weight of organic carbon) and its removal capacity was 11 μmole g-1 (dry weight of organic carbon). The remove rate of the FeOC material was 165 nmole day-1 g-1 (dry weight of organic carbon) and its minimum removal capacity was 105 mole g-1 (dry weight of organic carbon). Antimony removal rate of the OC material decreases from 8.2 to 1.4 nmole day-1 g-1 (dry weight of organic carbon) and its removal capacity is 2.4 μmole g-1 (dry weight of organic carbon). The minimum removal rate of FeOC material is 13 nmole day-1 g-1 (dry weight of organic carbon) and its minimum removal capacity is 8.4 μmole g-1 (dry weight of organic carbon). The As(III) : [As(III)+As(V)] ratio increased from 1% in the influent to 50% at 5.5 cm from the influent end, and to 80% at 15.5 cm from the influent end of the OC column. X-ray absorption near edge spectroscopy (XANES) shows As(III)-sulfide species on solid samples. These results suggest that As(V) is reduced to As(III) both in pore water and precipitate as As sulfides or coprecipitate with iron sulfides. The arsenic reduction rate suggests that As(V) reduction is mediated by bacterial activity in the OC column and that both abiotic reduction and bacterial reduction could be important in FeOC.

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.

La dépollution des eaux souterraines est actuellement une des principaux défis environnementaux, considérant le nombre de sites contaminés et le risque posé à la santé humaine et à l'environnement par l'exposition à la contamination des eaux souterraines. La barrière réactive perméable (PRB) est une technologie in situ passive pour la remédiation des eaux souterraines contaminées. Il se compose d'une barrière placée perpendiculairement à l'écoulement des contaminants et constituée d'un matériau réactif qui traite la panache de contaminants le traversant sous le gradient hydraulique naturel. C’est la technologie de remédiation des eaux souterraines la plus rentable ; elle permet l'utilisation des terres de surface et réduit l'exposition des travailleurs aux polluants. Le matériau réactif le plus utilisé est le fer à valence zéro (ZVI), qui peut dépolluer l'eau souterraine contaminée par une large gamme de contaminants au moyen de mécanismes chimiques et physiques différents. Le problème principal de l'utilisation de ZVI granulaire est la réduction de la porosité du milieu poreux, en raison de la nature expansive de produits de corrosion, des précipités et la formation de gaz. Pour surmonter ce problème, des mélanges de matériaux granulaires et ZVI ont été testés afin de déterminer leur efficacité de dépollution et le comportement hydraulique à long terme. L'utilisation de Lapillus volcaniques à mélanger avec ZVI pour dépolluer les eaux souterraines contaminées par métaux lourds est proposée dans ce travail. Des essais sur Lapillus ont montré une efficacité d'élimination de métaux lourds non négligeable, tandis que les tests en colonne effectuée en utilisant des mélanges n’ont pas montré une réduction élevée de la conductivité hydraulique au cours du temps.La modélisation des essais batch et colonne en tant qu’outil pour la compréhension des mécanismes impliqués dans les milieux poreux réactifs a été mis en place. L’étude de la sensibilité des paramètres des modèles sur leurs réponses a également été explorée. / Groundwater remediation is currently one of the major environmental challenges, considering the number of contaminated sites and the risk posed to human health and to the environment by exposure to groundwater contamination. Permeable reactive barrier (PRB) is a passive in situ technology for the remediation of contaminated groundwater. It consists of a barrier placed perpendicularly to the contaminant flow and made of reactive material that treats contaminant plume flowing through it under the natural hydraulic gradient. It is the most cost-effective groundwater remediation technology; it allows the use of surface land and reduces the exposure of workers to contaminants. The most used reactive material is Zero Valent Iron (ZVI), which is able to remediate groundwater contaminated by a large range of contaminants by means of different chemical and physical mechanisms. The main issue of granular ZVI use regards the reduction of the porous medium porosity, because of the expansive nature of corrosion products, precipitates and gas formation. To overcome this problem, mixtures of ZVI and granular materials were tested to investigate their long-term removal efficiency and hydraulic behavior. The use of volcanic Lapillus to be mixed with ZVI to remediate heavy-metals contaminated groundwater is proposed in this work. Tests on Lapillus showed a not negligible heavy metal removal efficiency of the volcanic material, while the hydraulic monitoring of column tests performed using mixtures showed a not high reduction of hydraulic conductivity over time.Modelling batch and column tests as a tool for understanding the mechanisms involved in the reactive porous media has been set up. The analysis of the sensitivity of the models response with respect to the input parameters has also been explored.

<p>Predmet izučavanja ove disertacije je ispitivanje mogućnosti primene homogenog, heterogenog i Fentonsličnog procesa u tretmanu obojenih otpadnih voda grafičke industrije.&nbsp; Kao Fenton katalizatori kori&scaron;ćeni su sintetisani gvožđe(III)-molibdat i nano nula valentno gvožđe, kao i komercijalni gvožđe(II)-sulfat. Istraživanja&nbsp; su sprovedena u četiri faze. U prvoj fazi&nbsp; je izvr&scaron;ena sinteza&nbsp; i karakterizacija&nbsp; Fenton&nbsp; katalizatora, pri čemu su ustanovljene njihove osnovne morfolo&scaron;ke karakteristike. Nano nula valentno gvožđe je sintetisano iz ekstrakta&nbsp; li&scaron;ća hrasta, dok je&nbsp; gvožđe(III)-molibdat sintetisan putem tzv. vlažnog hemijskog postupka. U drugoj fazi je&nbsp; izvr&scaron;ena optimizacija Fenton procesa u tretmanu sintetičkih rastvora grafičkih&nbsp; boja primenom nove statističke&nbsp; metode,&nbsp;<em> definitive screening design</em>.&nbsp; U&nbsp; cilju postizanja&nbsp; maksimalnog stepena obezbojavanja i mineralizacije tretiranog uzorka&nbsp; ispitan&nbsp; je&nbsp; uticaj&nbsp; sledećih&nbsp; procesnih parametara: inicijalne koncentracije boje, koncentracije gvožđa, pH vrednosti i koncentracije vodonik-peroksida. Nakon ustanovljenih optimalnih uslova i izvr&scaron;ene verifikacije predloženog optimuma, sproveden je tretman realnog efluenta.&nbsp; Stepen mineralizacije&nbsp; tretiranog&nbsp; efluenta&nbsp; ustanovljen&nbsp; je&nbsp; na&nbsp; osnovu&nbsp; vrednosti&nbsp; sadržaja&nbsp; ukupnog&nbsp; organskog&nbsp; ugljenika&nbsp; i&nbsp; hemijske&nbsp; potro&scaron;nje kiseonika.&nbsp; U cilju razumevanja mehanizma degradacije grafičkih boja u Fenton procesu, kao i identifikacije prirode&nbsp; degradacionih&nbsp; produkata,&nbsp; izvr&scaron;ena&nbsp; je&nbsp; kvalitativna&nbsp; gasno-hromatografska/maseno&nbsp; spektrometrijska analiza. Kinetika obezbojavanja realnog&nbsp; efluenta&nbsp; najbolje&nbsp; je opisana primenom&nbsp; Behnajady&nbsp; -&nbsp; Modirshahla&nbsp; -Ghanbary&nbsp; modela,&nbsp; koji&nbsp; defini&scaron;e&nbsp; inicijanu&nbsp; brzinu&nbsp; i&nbsp; oksidacioni&nbsp; kapacitet&nbsp; posmatranog&nbsp; procesa.&nbsp; Rezultati&nbsp; su ukazali&nbsp; na&nbsp; moguću&nbsp; primenu&nbsp; Fenton&nbsp; procesa&nbsp; u&nbsp; tretmanu&nbsp; CMYK&nbsp; boja&nbsp; usled&nbsp; postizanja&nbsp; visokih&nbsp; efikasnosti obezbojavanja i mineralizacije tretiranih efluenata. Nedostatak primenjene metode se ogleda u činjenici da je većina&nbsp; uzoraka&nbsp; okarakterisana&nbsp; kao&nbsp; visoko&nbsp; toksična,&nbsp; a&nbsp; ujedno&nbsp; i&nbsp; izrazito&nbsp; kisela,&nbsp; budući&nbsp; da&nbsp; je&nbsp; ustanovljena optimalna&nbsp; pH&nbsp; vrednost&nbsp; Fenton&nbsp; tretmana&nbsp; 2&nbsp; -&nbsp; 3.&nbsp; Stoga&nbsp; je&nbsp; u&nbsp; okviru&nbsp; treće&nbsp; faze&nbsp; istraživanja&nbsp; primenjen&nbsp; dodatni tretman&nbsp; realnog&nbsp; efluenta,&nbsp; adsorpcija&nbsp; na&nbsp; aktivnom&nbsp; uglju&nbsp; sintetisanom&nbsp; iz&nbsp; ko&scaron;tica&nbsp; divlje&nbsp; &scaron;ljive.&nbsp; Adsorpcioni tretman&nbsp; je rezultovao smanjenjem&nbsp; toksičnosti&nbsp; kod&nbsp; svih tretiranih uzoraka, koji&nbsp; se&nbsp; karakteri&scaron;u&nbsp; kao nisko do umereno toksični, te je sa tog aspekta moguće njihovo bezbedno ispu&scaron;tanje u recipijent. Ujedno je ustanovljena i povećana mineralizacija uzoraka, kao posledica degradacije jedinjenja koja su inicijalno doprinela povećanoj toksičnosti. U četvrtoj fazi rada primenjena je metoda ocenjivanja životnog ciklusa sinteze Fenton katalizatora. Rezultati LCA su utvrdili da sinteza heterogenog Fenton katalizatora, gvožđe(III)-molibdata, ostvaruje najveće opterećenje&nbsp; životne&nbsp; sredine,&nbsp; dok&nbsp; bi&nbsp; se&nbsp; proces&nbsp; sinteze&nbsp; nano&nbsp; nula&nbsp; valentnog&nbsp; gvožđa&nbsp; mogao&nbsp; unaprediti modifikovanjem ekstrakcione faze uz kori&scaron;ćenje alternativnih materijala i obnovljivih izvora energije. Značaj&nbsp; predstavljenih rezultata se ogleda u činjenici da su uzorci obojenih otpadnih voda grafičke industrije prvi put podvrgnuti Fenton tretmanu koji je rezultovao visokim stepenom efikasnosti.</p> / <p>The subject of this thesis is&nbsp; exploring the possibility of homogeneous, heterogeneous and Fenton-like process application in the treatment of dye wastewater in printing industry. Synthesized iron(III)-molybdate and nano zero valent iron, as well as commercial iron(II)-sulfate were used as a Fenton catalyst. The research was carried out in four&nbsp; phases.&nbsp; In&nbsp; the&nbsp; first&nbsp; phase,&nbsp; the&nbsp; catalyst&nbsp; synthesis&nbsp; and&nbsp; their&nbsp; characterization&nbsp; were&nbsp; performed,&nbsp; whereby&nbsp; the morphological characteristics were established. Nano zero valent iron was synthesized from&nbsp; oak leaf extract&nbsp; and iron(III)-molybdate was synthesized by wet chemical process. In the second phase, the optimization of Fenton process was performed within the treatment of synthetic printing dye solution using a new statistical method, a definitive screening design. In order to achieve maximum decolorization and mineralization of the treated sample, the influence of&nbsp; following&nbsp; process parameters was conducted: initial dye concentration, iron concentration, pH value&nbsp; and hydrogen peroxide concentration.&nbsp; The treatment of printing effluent was performed&nbsp; after&nbsp; establishing optimal&nbsp; conditions&nbsp; and&nbsp; verifying&nbsp; the&nbsp; proposed&nbsp; optimum&nbsp; values.&nbsp; Mineralization&nbsp; degree&nbsp; of&nbsp; treated&nbsp; effluent&nbsp; was determined based on the results of total organic carbon and chemical oxygen demand. In order to understand the dye&nbsp; degradation&nbsp; mechanism&nbsp; in&nbsp; Fenton&nbsp; process,&nbsp; as&nbsp; well&nbsp; as&nbsp; to&nbsp; identify&nbsp; degradation&nbsp; products,&nbsp; a&nbsp; qualitative&nbsp; gaschromatographic/mass spectrometric analysis was carried out. The&nbsp; kinetic studies of the printing effluent were best described by using the Behnajady- Modirshahla-Ghanbary model, which defines the initial speed and oxidation capacity of the process. The results indicated the possible application of the Fenton process in the treatment of CMYK dyes due to the high decolorization and mineralization efficiency of treated effluent. Disadvantage of the applied method is reflected in the fact that most of the samples are characterized as highly toxic and,&nbsp; at the same time, extremely acidic since the optimum pH value of Fenton treatment is 2 - 3. Therefore, in the third phase of the study, adsorption process on functionalized biochar prepared from wild plum kernels was applied on real printing effluent.&nbsp; Adsorption&nbsp; treatment&nbsp; resulted&nbsp; in&nbsp; toxicity&nbsp; reduction&nbsp; in&nbsp; all&nbsp; treated&nbsp; samples,&nbsp; characterized&nbsp; as&nbsp; low&nbsp; to moderately toxic. Therefore, from this aspect, treated effluent can be safely released into the recipient. At the same time, increased mineralization of the samples was established as a result of the compounds degradation that initially contributed to high toxicity. In the fourth phase, a life cycle assessment method of Fenton catalyst was applied. The results of the LCA indicated that the synthesis of the heterogeneous Fenton catalyst, iron(III) molybdate, achieved the highest environmental burden, while the synthesis of nano zero valent iron could be improved by modifying the extraction phase using alternative materials and renewable energy sources.&nbsp; The significance of the obtained results is high decolorization efficiency achieved by Fenton treatment of printing dye wastewater,&nbsp; which was used for the first time.</p>

Orientador: Jonas Contiero / Resumo: 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