Submitted by CAMILA MARIA ANDRADE DOS SANTOS null (camilaandr@gmail.com) on 2016-09-08T21:45:05Z No. of bitstreams: 1 Tese Camila Maria Andrade dos Santos.pdf: 6338259 bytes, checksum: b6c2f381dc20c8377b2481a922179786 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-09-12T21:19:54Z (GMT) No. of bitstreams: 1 santos_cma_dr_araiq.pdf: 6338259 bytes, checksum: b6c2f381dc20c8377b2481a922179786 (MD5) / Made available in DSpace on 2016-09-12T21:19:54Z (GMT). No. of bitstreams: 1 santos_cma_dr_araiq.pdf: 6338259 bytes, checksum: b6c2f381dc20c8377b2481a922179786 (MD5) Previous issue date: 2016-08-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho os efeitos da variação da concentração de Al sobre as transformações de fase e as propriedades mecânicas das ligas Cu-7%Al-10%Mn-3%Ag, Cu-10%Al-10%Mn- 3%Ag e Cu-11%Al-10%Mn-3%Ag foram estudadas utilizando-se metalografia por microscopias óptica (MO), eletrônica de varredura (MEV) e eletrônica de transmissão (MET), calorimetria exploratória diferencial (DSC), difratometria de raios X (DRX), ensaios de tensão-deformação, análise por dispersão de energias de raios X (EDXS), medidas de variação da resistividade elétrica com a temperatura e medidas de variação da microdureza com a temperatura e o tempo de envelhecimento. Os resultados obtidos para as ligas inicialmente submetidas a tratamento térmico de recozimento e inicialmente submetidas a tratamento térmico de têmpera mostraram que o aumento de 7 para 9%Al não modifica o comportamento térmico e a dureza das ligas Cu-7%Al-10%Mn-3%Ag e liga Cu-9%Al- 10%Mn-3%Ag, pois as curvas obtidas apresentaram o mesmo perfil, indicando que elas passam pelas mesmas transições. Porém, o aumento de 9 para 11%Al provoca uma mudança nas transformações pelas quais a liga passa, modificando assim o seu comportamento térmico e os valores da microdureza. Nas ligas inicialmente recozidas foi possível notar a ocorrência da decomposição espinodal em decorrência da retenção das fases 1 e 3 durante o resfriamento lento das amostras. Os resultados obtidos a partir das ligas submetidas a tratamento térmico de envelhecimento mostraram que aumento da dureza durante este processo está principalmente relacionado à precipitação bainítica. A partir das curvas de variação da microdureza com o tempo de envelhecimento foi possível obter os parâmetros cinéticos (n, k e Ea), utilizando-se as equações de Johnson-Mehl-Avrami-Kolmogorov (JMAK) e Arrhenius. Os valores de energia de ativação obtidos mostraram que o aumento na concentração de Al diminui Ea para o processo de precipitação. A diminuição destes valores deve estar associada principalmente à ocorrência da reação de precipitação de uma fase rica em Ag, que deve ocorrer com razoável intensidade na liga com 7%Al e vai diminuindo até não mais ser detectada na liga contendo 11%Al. Os resultados obtidos pelos testes de tensãodeformação indicaram que as ligas com maior teor de Al são mais frágeis. / In this work, the effects of changes in the Al concentration on the phase transformations and the mechanical properties of the Cu-7%Al-10%Mn-3% Ag, Cu-10%Al-10%Mn-3%Ag and Cu-11%Al-10%Mn-3% Ag alloys were studied using metallography by optical microscopy (OM), scanning electron microscopy (SEM) and electronic transmission mycroscopy (TEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), stress-strain tests, analysis by X-ray energy dispersing (EDXS), measurements of the variation of electrical resistivity with temperature and microhardness changes measurements with temperature and aging time. The results obtained for alloys initially annealed and initially quenched showed that the increase from 7 to 9% Al does not modify the thermal behavior and hardness of the Cu-7%Al- 10%Mn-3%Ag and Cu-9%Al-10%Mn-3%Ag alloys. However, the increase from 9 to 11%Al causes a change on the transformations of the alloys, thereby modifying their thermal behavior and values of microhardness. In the annealed alloys it was possible to notice the occurrence of the spinodal decomposition due to the retention of 1 and 3 phases during the slow cooling of the samples. The results obtained from aged alloys showed that the hardness increasing observed during this process is mainly related to bainitic precipitation. The isothermal ageing kinetics for this precipitation was studied considering four different ageing temperatures and the kinetic parameters n, k and Ea were obtained using the Johnson-MehlAvrami-Kolmogorov (JMAK) and the Arrhenius equations. The results showed that the increase on the Al concentration decreases the activation energy values for the precipitation process. This should be mainly associated with the occurrence of the precipitation reaction of an Ag-rich phase, that should occur with reasonable intensity in the alloy with 7%Al and decreases until it is no longer detectable in the alloy containing 11%Al. The results obtained for stress-strain testing indicated that the increase in the Al content increases the fragility of the alloys.

Made available in DSpace on 2014-12-17T15:55:03Z (GMT). No. of bitstreams: 1 AnaFSRN_DISSERT.pdf: 3363450 bytes, checksum: e0cb6b317ff11cb49abf8a59b8c7c5bc (MD5) Previous issue date: 2013-02-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The use of pesticides is being used intensively with severe consequences for exposed farmers. This study aimed to describe the socioeconomic and health profiles of 60 farmers in the city of Touros / RN through the questionnaire recommended by: (International Commission for Protection against Environmental Mutagens and Carcinogens (ICPEMC). The analysis of these data allowed to prove the importance of knowledge about the socioeconomic and health profile of rural farmers as a way to understand the reality of this population, that is vulnerable to exposure due to the lack of knowledge and conditions. Aiming to analyze the frequency of micronucleus (MN) and other nuclear abnormalities in oral mucosa cells of 54 farmers that work in the city of Touros / RN it was applied the micronucleus test (MN) in oral mucosa. Our results showed an increased frequency of MN and other nuclear abnormalities related to the exposure and effects of pesticides on health. Based on the results, it is clear that farmers are using pesticide in the wrong way and compromising their health. A Cordel has been developed as a method to taking the results to the people affected by the pesticides. Therefore this study alerts to the need for profound changes in the social, cultural and health context to reduce health risks for both people and for the environment / O uso de agrot?xicos esta sendo usado de maneira intensiva com graves consequ?ncias para os agricultores expostos. O presente estudo teve como objetivo descrever os perfis de sa?de e socioecon?mico de 60 agricultores no Munic?pio de Touros/RN atrav?s do question?rio recomendado por: (International Commission for Protection against Environmental Mutagens and Carcinogens (ICPEMC). As an?lises desses dados permitiu comprovar a import?ncia do conhecimento do perfil socioecon?mico e de sa?de de agricultores rurais como forma de entender a realidade dessa popula??o, que pela falta de conhecimentos e condi??es encontram-se vulner?veis a exposi??o de agrot?xicos. Com objetivo de analisar a frequ?ncia de micron?cleos (MN) e outras anormalidade nucleares em c?lulas da mucosa oral de 54 agricultores que trabalham no Munic?pio de Touros/RN aplicou-se o Teste de micron?cleo (MN) em mucosa bucal. Os nossos resultados mostraram uma frequ?ncia aumentada de MN e outras anormalidades nucleares relacionados com a exposi??o e efeitos dos defensivos agr?colas na sa?de. A partir dos resultados obtidos, fica not?rio que os agricultores est?o aplicando os agrot?xicos de maneira err?nea e comprometendo a sua sa?de. Como estrat?gia socioeducativas foi desenvolvido um Cordel baseado no texto e nos resultados encontrados no presente estudo. Desta forma este estudo alerta para a necessidade de profundas mudan?as sociais, culturais e no ?mbito da sa?de para diminuir os riscos a sa?de tanto para as pessoas quanto para o ambiente

Made available in DSpace on 2014-12-17T15:12:11Z (GMT). No. of bitstreams: 1 WanderlanSP_DISSERT.pdf: 791090 bytes, checksum: 1f1f88320e524c6875d48d14995e222d (MD5) Previous issue date: 2008-10-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Cette th?se a pour objectif principal examiner comment les M?non, Platon listes l'an?mnesis avec les autres th?ories qui sont abord?s dans ce dialogue et, par cons?quent, essayer de comprendre ce que c'est. Cette recherche vise dans un premier temps situ?es dans d'autres dialogues de Platon la survenance du terme anamn?sis ? veifique les points qui relient ces oeuvres ? clarifier la compr?hension d'un plus appropri? dans le M?non. Jetez-y aussi, quels sont les ?l?ments de la platonicienne th?orie de la connaissance sera reliant le dialogue afin de prouver que le M?non, qui est la question centrale aret?, garde un conflit dans la sophistique et la philosophie. Ce choc entre ce qui se passe papapep indirectement par l'interm?diaire de son M?non enseign?, et Socrates qui conteste la th?se de l'?thique et le relativisme ?pist?mologique. Nous voyons aussi, de quelle mani?re le dialogue est donn?e de prendre une voie d'acc?s au savoir qui est configur? comme s?rs, ? savoir an?mn?sis. L'interrogatoire de M?non depuis le d?but dans les appels d'enqu?ter ?ristique cet int?r?t, que lorsqu'ils sont confront?s ? des int?r?ts les am?nerait ? l'?tat apor?tique initial et qui est progressivement remplac? par l'aporie fondamental de connaissance, ce n'est point pour aporie la compr?hension de an?mnesis. En prenant la dialectique comme m?thode d'enqu?te dans le dialogue, il est n?cessaire de la part de Socrates et M?non, de quitter le didaskein et en profiter pour math?sis que la construction des connaissances. Il ouvre de mani?re un des principaux enjeux dans ce travail examine si le an?mnesis permettre l'acc?s aux moyens et si elle a un statut similaire ? mn?me. ? un moment o? Socrate explique dans le dialogue qui est le an?mnesis par monstration monstration fait avec esclave de M?non il est l'utilisation d'?l?ments mythiques que, selon notre analyse, permettre ? comprendre le sens de dialogue les connaissances qui montre l'opportunit? d'apprendre, qui est la an?mnesis / Esta disserta??o tem como principal objetivo analisar de que modo no M?non, Plat?o relaciona a an?mnesis a outras no??es que neste di?logo s?o discutidas e, deste modo, tentar compreender o que ela ? . Esta investiga??o visa inicialmente situar em outros di?logos plat?nicos a ocorr?ncia do termo an?mnesis para que verifique-se os aspectos que interligam estas obras a fim de precisar a compreens?o do sentido mais adequado no M?non. Verificar-se-? tamb?m, quais elementos da teoria do conhecimento plat?nica v?o se interligando no di?logo de modo a revelar que o M?non, que tem como quest?o central a aret?, resguarda um conflito entre a sof?stica e a filosofia. Tal embate acontece indiretamente entre G?rgias atrav?s do seu ensinado M?non, e S?crates que nega as teses do relativismo ?tico e epistemol?gico. Observamos tamb?m, de que forma se d? a assun??o de uma via de acesso ao conhecimento que se configura como mais segura, a saber, a an?mnesis. O questionamento de M?non desde o in?cio do di?logo nos instiga a inquirir esse interesse er?stico, que ao ser confrontado com os interesses socr?ticos levaria-os ao estado apor?tico inicial e que paulatinamente ? substitu?do pela aporia fundamental do conhecimento, esta aporia ? ponto de partida para a compreens?o da an?mnesis. Ao assumir-se a dial?tica como m?todo investigativo surge a necessidade por parte de S?crates e de M?non, de abandonar o didaskein e assumir a math?sis como possibilidade de constru??o do conhecimento. Abre-se assim uma das quest?es principais que este trabalho analisa, ? se a an?mnesis ? possibilidade acesso ?s Formas e se a mesma possui um estatuto similar a mn?me. No momento em que S?crates explicita no di?logo o que ? a an?mnesis, atrav?s da mostra??o feita com o escravo de M?non, h? a utiliza??o filos?fica de elementos m?ticos que, segundo nossa an?lise, permitem a compreens?o efetiva do sentido da constru??o dialogada do conhecimento que exterioriza o que se deseja aprender, ou seja: o que ? a an?mnesis

Made available in DSpace on 2015-05-14T13:21:34Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 8221472 bytes, checksum: cac315a193674c3a77482441306e409a (MD5) Previous issue date: 2013-11-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / An alternative route for the synthesis of the three isomers of Mn(III) N-metylpyridylporphyrins, MnTM-X-PyPCl5 (X = 2, 3, 4) was developed by the direct methylation of MnT-X-PyPCl (X = 2, 3, 4) with methyl tosylate; this methodology may be adapted for preparing the longer-alkyl-chain analogues. The investigation of the thermal stability of the potent redox modulator Mn(III) meso-tetrakis(N-ethylpyridinium-2- yl)porphyrin chloride (MnTE-2-PyPCl5) showed that the thermal decomposition of MnTE-2-PyPCl5∙11H2O under air occurs in three successive steps: dehydration, dealkylation (ethyl chloride loss) and combustion, to yield Mn oxide as final residue. Heating MnTE-2-PyPCl5∙11H2O up to ~100 ºC leads to dehydration, but with no effect onto the catalytic SOD activity after rehydration/dissolution. Heating the sample at temperatures above 100 ºC leads to dealkylation, which affects catalytic and biological properties. The immobilization of the neutral Mn porphyrins (MnPs) MnT-X-PyPCl (X = 2, 3, 4) covalently onto chloropropyl silica-gel (Sil-Cl) or the cationic MnPs MnTM-X-PyPCl5 (X = 2, 3, 4) electrostatically into sodium vermiculite (verm) yielded stable biomimetic models of cytochromes P450. The resulting materials, Sil-Cl/MnT-X-PyPCl e verm/MnTM-X-PyPCl5 (X = 2, 3, 4), were used as oxidation catalyst for hydroxylation of cyclohexane and adamantane by iodosylbenzene. The heterogeneous systems were more efficient, selective, and oxidatively stable than the homogeneous counterparts, and could be reused three times with no significant loss in efficiency. The use of more drastic conditions (i.e., large excess of PhIO), led to considerable decrease in efficiency, which was partial recovered upon catalyst reuse uner milder conditions, indicating that the support protects the supported MnP against oxidative degradation. The materials efficiently catalyzed the oxidation of cyclohexanol to cyclohexanone, suggesting that the ketone observed during cyclohexane hydroxylation may result, at least partially, from cyclohexanol oxidation. The covalent bond between Sil-Cl and MnPs via N-pyridyl moiety allowed the preparation of efficient and stable catalysts, even with first generation, simple MnPs, such as MnT-X-PyPCl (X = 2, 3, 4). Vermiculite was revealed as a simple and effective support for rapid and qualitative immobilization of cationic MnPs, MnTM-X-PyPCl5 (X = 2, 3, 4). Grinding of the vermiculite-based materials decreased the crystallinity of the systems, which was followed by an increase in the catalytic efficiency of the meta and para isomers verm/MnTM-X-PyPCl5 (X = 3 and 4), but did not affect of the high efficiency of the immobilized ortho isomer (verm/MnTM-2-PyPCl5), whose resistance to oxidative destruction and/or leaching was, additionally, higher than that of the other isomers. / Neste trabalho foi desenvolvida uma rota alternativa para obtenção dos três isômeros das N-metilpiridinioporfirinas de Mn(III), MnTM-X-PyPCl5 (X = 2, 3, 4), a partir da metilação direta dos complexos MnT-X-PyPCl (X = 2, 3, 4) com tosilato de metila; esta metodologia pode ser adaptada para obtenção de derivados alquilas de cadeias maiores. A investigação da estabilidade térmica do modulador redox potente cloreto de meso-tetraquis(N-etilpiridinio-2-il)porfirinatomanganês(III) (MnTE-2-PyPCl5) revelou que a decomposição térmica da MnTE-2-PyPCl5∙11H2O em ar ocorre em três etapas sucessivas, associadas à desidratação, desalquilação (perda dos grupos EtCl) e combustão, levando a óxidos de Mn como resíduo final. O aquecimento da MnTE-2- PyPCl5∙11H2O até ~100 °C leva à desidratação, mas não afeta a atividade catalítica SOD após a re-hidratação/dissolução. O aquecimento da amostra à temperatura elevada (>100 oC) leva à desalquilação e compromete as propriedades catalíticas e biológicas da amostra. O desenvolvimento de modelos biomiméticos dos citocromos P450 pela heterogeneização covalente das Mn-porfirinas (MnPs) neutras MnT-X-PyPCl (X = 2, 3, 4) na sílica cloropropil (Sil-Cl) e pela heterogeneização eletrostática das MnPs catiônicas MnTM-X-PyPCl5 (X = 2, 3, 4) na vermiculita de sódio (verm) foi estudado. Os materiais resultantes, Sil-Cl/MnT-X-PyPCl e verm/MnTM-X-PyPCl5 (X = 2, 3, 4), foram empregados como catalisadores em reações de hidroxilação de cicloexano e adamantano por iodosilbenzeno (PhIO). Os catalisadores heterogeneizados foram mais eficientes, seletivos e resistentes à destruição oxidativa do que os catalisadores em meio homogêneo, e foram reutilizados por três vezes sem perda significativa na eficiência catalítica. Sob condições mais drásticas, com o uso de grande excesso de PhIO, há diminuição considerável da eficiência, mas os catalisadores imobilizados puderam ser reutilizados com recuperação parcial da eficiência, o que indica que o suporte exerce proteção das MnPs contra degradação oxidativa. Os catalisadores heterogeneizados foram eficientes ao catalisar a oxidação do cicloexanol à cicloexanona, sugerindo que a cetona observada nas hidroxilações pode advir da oxidação seqüencial, cicloexano-cicloexanol-cicloexanona. A ligação covalente entre a Sil-Cl e as MnPs via grupo N-piridil possibilitou a obtenção de catalisadores eficientes e estáveis, mesmo utilizando MnPs simples de primeira geração, MnT-X-PyPCl (X = 2, 3, 4). Já a vermiculita mostrou-se um suporte simples e efetivo para imobilização rápida e quantitativa de MnPs catiônicas, MnTM-X-PyPCl5 (X = 2, 3, 4). A pulverização dos materiais à base de vermiculita diminuiu a cristalinidade dos sistemas, promoveu um aumento na eficiência dos isômeros meta e para (verm/MnTM-X-PyPCl5, X = 3 e 4), mas não modificou a alta eficiência do isômero orto imobilizado (verm/MnTM-2-PyPCl5), cuja resistência à destruição oxidativa e/ou lixiviação foi superior à dos outros isômeros.

Submitted by Onia Arantes Albuquerque (onia.ufg@gmail.com) on 2018-11-06T13:54:30Z No. of bitstreams: 2 Dissertação - Jhonny Willians de Oliveira Maciel - 2018.pdf: 3229754 bytes, checksum: 23b20bfd316d193ccfafa525bf314c79 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-11-07T09:38:43Z (GMT) No. of bitstreams: 2 Dissertação - Jhonny Willians de Oliveira Maciel - 2018.pdf: 3229754 bytes, checksum: 23b20bfd316d193ccfafa525bf314c79 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-11-07T09:38:43Z (GMT). No. of bitstreams: 2 Dissertação - Jhonny Willians de Oliveira Maciel - 2018.pdf: 3229754 bytes, checksum: 23b20bfd316d193ccfafa525bf314c79 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-09-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / New supramolecular systems based on metal complexes of formula [Fe(H2pcpa)2(H2O)2] (3), [Mn(Hpcpa)(H2O)3]n•1/2H2O (4), [Zn(Hpcpa)(H2O)3]n•1/2H2O (5) and [Cu2(Hpcpa)2(bipy)2]•5,6H2O (6) [H2pcpa- and Hpcpa2- ion derivative of EtH2pcpa (1) = N-(4-carboxyphenyl)oxamic ethyl ester] have been synthesized and describe in this work. The structure of 3 consists of discrete Fe(II) units, each metal ion is six-coordinate in a distorted octahedral environment with four oxamate-oxygens from a H2pcpa- ligand in the basal plane and two water molecules in the apical position. 4 and 5 is a neutral zigzag chain of Mn(II) and Zn(II) ions, respectively, bridged by Hpcpa2- ligands exhibiting the bidentate/monodentate coordination mode. Each metal ion is building a somewhat distorted octahedral surrounding. The distance between metals ions intrachain is 11.456 Å (4) and 11.325 Å (5). Complex 6 consists of a dimer in which the Cu(II) ions is found in a square-shaped pyramidal geometry connected by two Hpcpa2- and the 2,2'-bipyridine as a terminal ligand. / Foram obtidos novos sistemas supramoleculares baseados em compostos de coordenação com o ligante ácido N-(4-carboxifenil) oxâmico etil éster (EtH2pcpa/1) e os metais Fe(II), Mn(II), Cu(II) e Zn(II). As sínteses, caracterizações espectroscópicas e elucidação das estruturas cristalinas de quatro compostos inéditos de fórmula [Fe(H2pcpa)2(H2O)2] (3), [Mn(Hpcpa)(H2O)3]n•1/2H2O (4), [Zn(Hpcpa)(H2O)3]n•1/2H2O (5) e [Cu2(Hpcpa)2(bipy)2]•5,6H2O (6) foram descritas nesse trabalho. O complexo 3 formou monocristais de cor laranja amarronzada, cuja a estrutura consiste em um monômero de Fe(II). Cada íon de Fe(II) é hexacoordenado com esfera de coordenação composta de duas moléculas de água posicionadas em trans e quatro oxigênios-oxamato de dois ligante H2pcpa-. Os compostos 4 e 5 formaram monocristais transparentes incolores cujas estruturas cristalinas são formadas por cadeias em ziguezague neutras de íons Mn(II) e Zn(II), respectivamente. Cada íon metálico está hexacoordenado com as três moléculas de água posicionadas em Meridional, dois oxigênios-oxamato de um ligante Hpcpa2- e um oxigênio-carboxilato de um outro grupo do Hpcpa2-. A distância entre os metais intracadeia Mn...Mn no complexo 4 é de 11,456 Å e Zn...Zn no complexo 5 é de 11,325 Å. O complexo 6 formou monocristais azuis, a estrutura consiste em um dímero em que o íon de Cu(II) encontra-se penta coordenado em uma geometria piramidal de base quadrada com dois íons de Cu(II) ligados por dois ligantes Hpcpa2- e com o ligante 2,2'-bipiridina atuando como ligante terminal.

Os aços inoxidáveis austeníticos são os mais utilizados em situações onde é indispensável resistência à corrosão e excelentes propriedades mecânicas. O níquel costuma ser o principal elemento de liga utilizado na estabilização da fase austenítica, e nos últimos anos seu valor, de acordo com a London Metal Exchange, sofreu variações abruptas de preço, desestabilizando o mercado do aço inoxidável. Nesse contexto os aços da série 200, também conhecidos como aços Cr-Mn-Ni, que substituem parte do níquel por manganês para manter a estabilidade da fase austenítica, tiveram sua produção incrementada. O objetivo do presente trabalho foi comparar a resistência à corrosão por pite de dois aços inoxidáveis austeníticos, aço 17Cr-6Mn-5Ni (designado como aço 298, não normalizado) e o aço UNS S30403. Para tanto, foram estudadas duas variáveis: o efeito da temperatura de solubilização e da composição química do eletrólito, a qual foi constituída por soluções aquosas com teor fixo de 0,6M NaCl e adições progressivas de Na2SO4 visando verificar o efeito inibidor do íon sulfato nos diferentes aços com os diferentes tratamentos de solubilização (1010°C, 1040°C, 1070°C e 1100°C). A corrosão por pite foi determinada através de ensaios de polarização potenciodinâmica cíclica e os resultados obtidos foram discutidos através das variações microestruturais encontradas. Foram empregadas técnicas de microscopia ótica e eletrônica de varredura, análises por dispersão de energia, difração de raios X, medidas magnéticas com ferritoscópio e análise de imagem para quantificação da fase ferrita. Primeiramente, constatou-se que, na maioria das condições de composição química de eletrólito e tratamento térmico, em geral o aço UNS S30403 apresenta maior potencial de pite do que o aço 298. Mais detalhadamente, os resultados mostraram que a adição de íon sulfato aumenta a resistência à corrosão por pite em meio contendo cloreto dos aços 298 e UNS S30403 em todas as condições de tratamento térmico, sendo que o efeito benéfico da adição de sulfato é mais acentuado para o aço 298. O tratamento de solubilização teve pouca influência sobre a resistência à corrosão por pite do aço UNS S30403 (considerando-se cada eletrólito isoladamente); por outro lado, o aço 298 apresentou forte dependência com o tratamento térmico: na ausência de sulfato (0,6M NaCl) os tratamentos de solubilização diminuíram o potencial de pite; já na presença de sulfato, teores crescentes de Na2SO4 tiveram um efeito benéfico, cada vez mais forte, chegando ao ponto de atingir, para as concentrações de 0,6M Na2SO4 nas condições de tratamento térmico a 1070°C e 1100°C, potenciais de pite mais elevados do que os respectivos para o aço UNS S30403. Foi detectada a presença de uma segunda fase (ferrita, enriquecida em cromo) em ambos os aços (UNS S30403 e 298), e a presença de precipitados ricos em manganês no aço 298. Os distintos comportamentos foram explicados através da solubilização dos precipitados ricos em manganês. Concluiu-se que a dissolução, de tais precipitados, permitiu o aumento do teor de manganês na matriz austenítica do aço 298, sendo que a consequência disso, para o eletrólito puro em NaCl, foi a diminuição do potencial de pite desse aço, enquanto que na presença de sulfato, o efeito inibidor desse íon foi potencializado devido a maior afinidade química entre o íon sulfato e o elemento manganês - agora em solução sólida comparativamente àquela do íon cloreto e este elemento. Como o aço UNS S30403 não apresenta manganês como elemento de liga, nem consequentemente os precipitados ricos nesse elemento, o efeito deletério da solubilização, não foi observado em NaCl, e o efeito benéfico da adição de Na2SO4, sobre a resistência à corrosão por pite, não foi significativo para esse aço em função da temperatura de solubilização. / Austenitic stainless steels are widely used when both high corrosion and mechanical resistance are essentials. In general, nickel is added to stainless steels to stabilize the austenite phase. During the last decade, the nickel price fluctuated considerably; unstabling the stainless steel global market. The 200 series stainless steels, also known as Cr-Mn-Ni stainless steels, emerged as an alternative for traditional austenitic steels. In these steels, manganese replaces a fraction of nickel content, maintaining stable the austenitic phase. Consequently, the production of stainless steel containing manganese has increased notoriously. The present study has the aim to compare the pitting resistance corrosion, between the 17Cr-6Mn-5Ni (designated as 298) and UNS S30403 austenitic stainless steels. The effect of solution heat treatment temperature, and the chemical composition of environment aqueous solution were evaluated (the electrolytes used are constituted for aqueous solution with 0,6M NaCl fixed and Na2SO4 progress additions) verifying the inhibitor effect of sulfate ion in both steels on distinct temperature ranges (1010°C, 1040°C, 1070°C and 1100°C) defined for the solution heat treatments. The pitting corrosion resistance was determined by means of cyclic potentiodynamic polarization, and the answers obtained were discussed through the microstructural variations found. Optical and electron microscopy technique, X ray diffraction analysis, magnetic measurements using the ferritoscope and image analysis to ferrite phase quantification were used during this investigation. In most conditions examined, the UNS S30403 steel show highest pitting potential that 298 steel. In more detail, the results showed that addition of sodium sulfate increased the pitting corrosion resistance in media containing chloride ions of both UNS S30403 and 298 steels, in all heat treatment conditions, being more pronounced in 298 steel. The solution heat treatment had little influence on pitting resistance corrosion of UNS S30403 steel (considering separately each electrolyte); on the other hand, the 298 steel showed a strong dependence with the heat treatments: in absence of sulfate (0,6M NaCl) the heat treatments decreased the pitting corrosion resistance, but in presence of sulfate, the gradual increment of Na2SO4 concentration had a beneficial effect, each time more strong, reaching, for 0,6M NaCl+0,6M Na2SO4 condition in heat treatment temperatures 1070°C and 1100°C, higher pitting potential values than UNS S30403 steel. The presence of a chromium-rich second phase (chromium ferrite) in both steels (UNS S30403 and 298) and manganese-rich precipitates in 298 steel were detected. The different behaviors were explained through annealing solution of manganese-rich precipitates found in 298 steel. It is concluded that after heat treatments, the dissolution of these precipitates increased the manganese content in solid solution in 298 steel. Consequently decreasing the pitting potential values for 0,6M NaCl electrochemical condition (environment without Na2SO4). On the other hand, in presence of Na2SO4 the inhibitor effect is potentialized due to highest chemical affinity between ion sulfate and manganese (now in solid solution) compared to that between chloride ion and manganese. The UNS S30403 stainless steel does not contain manganese as alloying element, nor manganese-rich precipitates, deleterious effect in 0,6M NaCl was not observed, and the beneficial effect on pitting corrosion resistance due the sulfate additions was not significantly different in this steel when the annealing solution temperature is changed.

Weltweit wird ein großer Teil der Energie für die Kühlung unterschiedlichster Arten verwendet und der Bedarf steigt weiterhin an. Herkömmliche Kühlsysteme funktionieren mittels Kompression von Gasen mit sehr niedriger Verdampfungstemperatur. Diese Kältemittel sind entweder giftig, brennbar oder klimaschädlich. Deshalb zielen aktuelle Forschungsschwerpunkte auf alternative und nachhaltige Kühlsysteme. Eine vielversprechende Alternative ist der Einsatz von Festkörpern mit Phasenumwandlungen. Die durch verschiedene (magnetische, elektrische oder elastische) Felder induzierten Phasenübergänge ermöglichen die Nutzung kalorischer Effekte. Der magnetokalorische Effekt (MKE) beschreibt das physikalische Phänomen, bei dem ein sich veränderndes äußeres Magnetfeld unter adiabatischen Bedingungen zu einer Temperaturänderung in einem magnetischen Material führt. Für die Nutzung des MKE in Kühlsystemen stellen die Ni-Mn-X (X = Ga, In, Sb, Sn) Heusler-Legierungen eine geeignete Materialklasse dar. Sie besitzt mit ihrer gekoppelten magnetostrukturellen Umwandlung, bei der eine martensitische Phasenumwandlung auch die magnetischen Eigenschaften ändert, ein großes Potential für einen MKE. Beim Absenken der Temperatur unter die Umwandlungstemperatur kommt es zu einer diffusionslosen Strukturumwandlung von einer hohen zu einer niedrigeren Kristallsymmetrie. Dabei wird die Hochtemperaturphase als Austenit und die Niedrigtemperaturphase als Martensit bezeichnet. Werden einige Atomprozent Kobalt zu Ni-Mn-Ga hinzulegiert, ändern sich die magnetischen Eigenschaften der Phasen deutlich. So zeigt Ni-Mn-Ga-Co einen magnetostrukturellen Übergang zwischen der ferromagnetischen Austenitphase und der ferrimagnetischen Martensitphase und damit einen inversen MKE. Beim Anlegen eines äußeren magnetischen Feldes kommt es demnach zu einer Abkühlung des funktionalen Materials und damit zu positiven Werten der Entropieänderung. Für die Anwendung dieser Festkörper als Kühlelemente in Mikrosystemen ist die Entwicklung und Charakterisierung dünner Schichten nötig. Ihr hohes Oberflächen-zu-Volumen-Verhältnis ermöglicht einen schnellen Wärmeaustausch mit dem umgebenden Medium, wodurch hohe Zyklusfrequenzen erreichbar sind. Entsprechend können hohe spezifische Kühlleistungen erzielt werden. Epitaktische Ni-Mn-basierende Heusler-Legierungsschichten sind außerdem ein gutes Modellsystem für die Untersuchung des Einflusses von Ober- und Grenzflächen auf die Phasenumwandlung und die Materialeigenschaften und erlauben Untersuchungen zu den Ursachen der Hysterese, die bei einer martensitischen Phasenumwandlung auftritt. In dieser Arbeit werden epitaktisch gewachsene Ni-Mn-Ga-Co-Schichten, die eine gekoppelte strukturelle und magnetische Phasenumwandlung nahe Raumtemperatur besitzen, hergestellt und charakterisiert. Ausgehend von Vorarbeiten zu Ni-Mn-X-Schichten und vielversprechenden Zusammensetzungen, die von Massivmaterialproben bekannt sind, wird durch die Variation der Herstellungsparameter und der chemischen Zusammensetzung der Schichten, magnetostrukturelle Umwandlungen mit scharfen Umwandlungsbereichen und geringer thermischen Hysterese bei großer Magnetisierungsänderung erzielt. Anhand von zwei mittels Kombinatorik hergestellter Probenserien wird der Einfluss des Kobalt-Gehaltes auf strukturelle, magnetische und kalorische Eigenschaften untersucht und entspricht den Ergebnissen von Untersuchungen an Ni-Mn-Ga-Co-Massivmaterialien. Es wird gezeigt, wie sich die magnetischen und kalorischen Eigenschaften der Schichten nach der Ablösung vom Substrat ändern. Die Entropieänderung, die ein für die kalorischen Eigenschaften sehr wichtiger Parameter ist, wird indirekt mit Hilfe geeigneter Magnetisierungsmessungen bestimmt und zeigt vielversprechende Werte von bis zu 9,9 J/(kg K). Die Ergebnisse der verschiedenen Messwege durch den Magnetfeld-Temperatur-Phasenraum werden verglichen und die Unterschiede entsprechend des Nukleations- und Wachstumsmodells der martensitischen Umwandlung erläutert. Die Umwandlungszyklenzahl beeinflusst die Wiederholbarkeit der temperaturabhängigen Magnetisierungskurven und damit auf strukturelle und magnetische Eigenschaften der Schichten deutlich und reduziert die thermische Hysterese. Mittels unvollständiger Umwandlungszyklen kann die martensitische Umwandlung derart beeinflusst werden, dass sich die thermische Hysterese reduzieren lässt. Dadurch werden bestehende Nukleations- und Wachstumsmodelle der martensitischen Umwandlung bestätigt.

Weltweit wird ein großer Teil der Energie für die Kühlung unterschiedlichster Arten verwendet und der Bedarf steigt weiterhin an. Herkömmliche Kühlsysteme funktionieren mittels Kompression von Gasen mit sehr niedriger Verdampfungstemperatur. Diese Kältemittel sind entweder giftig, brennbar oder klimaschädlich. Deshalb zielen aktuelle Forschungsschwerpunkte auf alternative und nachhaltige Kühlsysteme. Eine vielversprechende Alternative ist der Einsatz von Festkörpern mit Phasenumwandlungen. Die durch verschiedene (magnetische, elektrische oder elastische) Felder induzierten Phasenübergänge ermöglichen die Nutzung kalorischer Effekte. Der magnetokalorische Effekt (MKE) beschreibt das physikalische Phänomen, bei dem ein sich veränderndes äußeres Magnetfeld unter adiabatischen Bedingungen zu einer Temperaturänderung in einem magnetischen Material führt. Für die Nutzung des MKE in Kühlsystemen stellen die Ni-Mn-X (X = Ga, In, Sb, Sn) Heusler-Legierungen eine geeignete Materialklasse dar. Sie besitzt mit ihrer gekoppelten magnetostrukturellen Umwandlung, bei der eine martensitische Phasenumwandlung auch die magnetischen Eigenschaften ändert, ein großes Potential für einen MKE. Beim Absenken der Temperatur unter die Umwandlungstemperatur kommt es zu einer diffusionslosen Strukturumwandlung von einer hohen zu einer niedrigeren Kristallsymmetrie. Dabei wird die Hochtemperaturphase als Austenit und die Niedrigtemperaturphase als Martensit bezeichnet. Werden einige Atomprozent Kobalt zu Ni-Mn-Ga hinzulegiert, ändern sich die magnetischen Eigenschaften der Phasen deutlich. So zeigt Ni-Mn-Ga-Co einen magnetostrukturellen Übergang zwischen der ferromagnetischen Austenitphase und der ferrimagnetischen Martensitphase und damit einen inversen MKE. Beim Anlegen eines äußeren magnetischen Feldes kommt es demnach zu einer Abkühlung des funktionalen Materials und damit zu positiven Werten der Entropieänderung. Für die Anwendung dieser Festkörper als Kühlelemente in Mikrosystemen ist die Entwicklung und Charakterisierung dünner Schichten nötig. Ihr hohes Oberflächen-zu-Volumen-Verhältnis ermöglicht einen schnellen Wärmeaustausch mit dem umgebenden Medium, wodurch hohe Zyklusfrequenzen erreichbar sind. Entsprechend können hohe spezifische Kühlleistungen erzielt werden. Epitaktische Ni-Mn-basierende Heusler-Legierungsschichten sind außerdem ein gutes Modellsystem für die Untersuchung des Einflusses von Ober- und Grenzflächen auf die Phasenumwandlung und die Materialeigenschaften und erlauben Untersuchungen zu den Ursachen der Hysterese, die bei einer martensitischen Phasenumwandlung auftritt. In dieser Arbeit werden epitaktisch gewachsene Ni-Mn-Ga-Co-Schichten, die eine gekoppelte strukturelle und magnetische Phasenumwandlung nahe Raumtemperatur besitzen, hergestellt und charakterisiert. Ausgehend von Vorarbeiten zu Ni-Mn-X-Schichten und vielversprechenden Zusammensetzungen, die von Massivmaterialproben bekannt sind, wird durch die Variation der Herstellungsparameter und der chemischen Zusammensetzung der Schichten, magnetostrukturelle Umwandlungen mit scharfen Umwandlungsbereichen und geringer thermischen Hysterese bei großer Magnetisierungsänderung erzielt. Anhand von zwei mittels Kombinatorik hergestellter Probenserien wird der Einfluss des Kobalt-Gehaltes auf strukturelle, magnetische und kalorische Eigenschaften untersucht und entspricht den Ergebnissen von Untersuchungen an Ni-Mn-Ga-Co-Massivmaterialien. Es wird gezeigt, wie sich die magnetischen und kalorischen Eigenschaften der Schichten nach der Ablösung vom Substrat ändern. Die Entropieänderung, die ein für die kalorischen Eigenschaften sehr wichtiger Parameter ist, wird indirekt mit Hilfe geeigneter Magnetisierungsmessungen bestimmt und zeigt vielversprechende Werte von bis zu 9,9 J/(kg K). Die Ergebnisse der verschiedenen Messwege durch den Magnetfeld-Temperatur-Phasenraum werden verglichen und die Unterschiede entsprechend des Nukleations- und Wachstumsmodells der martensitischen Umwandlung erläutert. Die Umwandlungszyklenzahl beeinflusst die Wiederholbarkeit der temperaturabhängigen Magnetisierungskurven und damit auf strukturelle und magnetische Eigenschaften der Schichten deutlich und reduziert die thermische Hysterese. Mittels unvollständiger Umwandlungszyklen kann die martensitische Umwandlung derart beeinflusst werden, dass sich die thermische Hysterese reduzieren lässt. Dadurch werden bestehende Nukleations- und Wachstumsmodelle der martensitischen Umwandlung bestätigt.

Um den ständig steigenden Energiebedarf durch Kälteanlagen wie Kühlschränke oder Klimaanlagen zu verringern, sind in den vergangenen Jahren Kühlprozesse in den Mittelpunkt aktueller Forschungen gerückt, die auf Phasenumwandlungen in Festkörpern beruhen. Ein Beispiel dafür sind magnetokalorische Materialien, zu denen auch das in der vorliegenden Arbeit untersuchte Ni-Mn-Ga-Co gehört. In dieser Heusler-Legierung tritt eine Phasenumwandlung erster Ordnung von einer ferromagnetischen, kubischen Hochtemperaturphase (Austenit) in eine tetragonal verzerrte Tieftemperaturphase (Martensit) mit geringerer Magnetisierung auf. Der Unterschied in den Magnetisierungen beider Phasen erlaubt es auch, diese Phasenumwandlung durch ein Magnetfeld zu induzieren. Hierbei kühlt sich das Material durch eine Verringerung der Gitterentropie in dem System ab. Ein Nachteil von Phasenumwandlungen erster Ordnung ist die damit verbundene Hysterese. Außerdem lässt sich der magnetokalorische Effekt durch die scharfe Umwandlung nur in einem kleinen Temperaturbereich effektiv nutzen. Das Ziel dieser Arbeit besteht darin, anhand epitaktisch gewachsener Ni-Mn-Ga-Co-Schichten auf PMN-PT-Substraten zu untersuchen, ob und wie die Umwandlungstemperatur und damit auch die Hysterese der Heusler-Legierung durch mechanische Spannung beeinflusst werden kann. Dafür soll durch Anlegen eines elektrischen Feldes an das piezoelektrische Substrat die Ni-Mn-Ga-Co-Schicht reversibel mechanisch verspannt und die daraus resultierenden Veränderungen der strukturellen und magnetischen Eigenschaften untersucht werden. Im ersten Ergebnisteil wird zunächst gezeigt, dass epitaktische Ni-Mn-Ga-Co-Schichten auf PMN-PT wachsen können und diese einen strukturellen und magnetischen Phasenübergang zeigen. Eine Beeinflussung der bei Raumtemperatur vorliegenden Phase ist dabei über eine Variation der chemischen Zusammensetzung der Probe möglich. Im Anschluss werden die Auswirkungen eines angelegten elektrischen Feldes auf die strukturellen und magnetischen Eigenschaften analysiert. Röntgenuntersuchungen zeigen, dass die piezoelektrische Dehnung des Substrats vollständig auf das Ni-Mn-Ga-Co übertragen werden kann. Allerdings treten bei hohen Temperaturen aufgrund einer Phasenumwandlung im PMN-PT nichtlineare Dehnungseffekte auf. Eine Veränderung der Umwandlungstemperaturen durch die Dehnung des Ni-Mn-Ga-Co ist jedoch nicht möglich. Als wahrscheinliche Ursache dafür wird eine Besonderheit des martensitischen Gefüges der Ni-Mn-Ga-Co-Schichten diskutiert. Im Austenit wurde jedoch eine vollständig reversible Änderung der Magnetisierung um bis zu 7 % gemessen. Diese Magnetisierungsänderung bietet einen interessanten Anknüpfungspunkt für weitergehende Untersuchungen dieses Systems für multikalorische Anwendungen.

<p>Prisusutvo&nbsp; arsena&nbsp; u&nbsp; podzemnim&nbsp; vodama,&nbsp; koje&nbsp; se&nbsp; primenjuju&nbsp; za vodosnabdevanje stanovni&scaron;tva je globalan problem. Različiti&nbsp; konvencionalni<br />procesi&nbsp; se primenjuju&nbsp; za&nbsp; uklanjanje&nbsp; arsena iz vode, uključujući koagulaciju i<br />flokulaciju,&nbsp; sorpciju,&nbsp; membransku&nbsp; filtraciju&nbsp; i&nbsp; jonsku&nbsp; izmenu.&nbsp; Uzimajući&nbsp; u<br />obzir relativnu nisku cenu, jednostavnu kontrolu procesa i održavanje, visok<br />stepen uklanjanja arsena, sorpcija se smatra jednom od najpodobnijih tehnika<br />za uklanjanje arsena u tretmanu vode za piće. Premda su na trži&scaron;tu dostupni<br />različiti&nbsp; sorbenti&nbsp; za&nbsp; uklanjanje&nbsp; arsena,&nbsp; postoji&nbsp; potreba&nbsp; za&nbsp; iznalaženjem&nbsp; i<br />razvojem&nbsp; novih&nbsp;<em> low-cost&nbsp;</em> sorbenata,&nbsp; a&nbsp; kojima&nbsp; bi&nbsp; se&nbsp; pak&nbsp; mogao&nbsp; obezbediti<br />visok stepen uklanjanja oba oksidaciona oblika&nbsp; arsena,&nbsp; i&nbsp; As(III) i As(V). Cilj<br />ovog rada bio je usmeren na sintezu i karakterizaciju novih sorbenata na bazi<br />gvožđa&nbsp; i&nbsp; mangana&nbsp; odnosno&nbsp; Fe-Mn&nbsp; binarnog&nbsp; oksida,&nbsp; ispitivanje&nbsp; njihovog<br />potencijala&nbsp; za&nbsp; uklanjanje&nbsp; arsena&nbsp; iz&nbsp; vode&nbsp; i&nbsp; utvrđivanje&nbsp; da&nbsp; li&nbsp; novosintetisani<br />sorbenti po pitanju efikasnosti, mogu konkurisati postojećim komercijalnim i<br />&scaron;iroko kori&scaron;ćenim sorbentima u tretmanima voda.<br />Metodom&nbsp; precipitacije,&nbsp; sintetisani&nbsp; su&nbsp; Fe-Mn&nbsp; binarni&nbsp; oksidi&nbsp; sa&nbsp; različitim Fe:Mn&nbsp; molskim&nbsp; odnosima&nbsp; 1:1,&nbsp; 3:1,&nbsp; 6:1&nbsp; i&nbsp; 9:1,&nbsp; dok&nbsp; su&nbsp; kombinacijom heterogene&nbsp; nukleacione&nbsp; tehnike&nbsp; i&nbsp; precipitacije,&nbsp; sintetisana&nbsp; i&nbsp; četiri&nbsp; sorbenta magnetnih&nbsp; svojstava&nbsp; (Mag,&nbsp; Mag-Fe,&nbsp; Mag-Mn,&nbsp; Mag-FeMn).&nbsp; Modifikacijom biopolimera&nbsp; Chitosana&nbsp; i&nbsp; GAC,&nbsp; sa&nbsp; Fe-Mn&nbsp; binarnim&nbsp; oksidom,&nbsp; razvijena&nbsp; su preostala&nbsp; dva&nbsp; materijala&nbsp; Chit-FeMn,&nbsp; odnosno&nbsp; GAC-FeMn.&nbsp; Sintetisani sorbenti su karakterisani različitim tehnikama i metodama (SEM/EDS, XRD,FTIR, BET).Fizičko-hemijskom karakterizacijom sintetisanih sorbenata ustanovljeno je da se Fe-Mn binarni oksidi i magnetni materijali, karakteri&scaron;u relativno velikim specifičnim&nbsp; povr&scaron;inama&nbsp; (109-300&nbsp; m²/g)&nbsp; i&nbsp; zapreminama&nbsp; mezopora (0,144-0,403&nbsp; cm ³ /g).&nbsp; Velika&nbsp; specifična&nbsp; povr&scaron;ina&nbsp; i&nbsp; razvijena&nbsp; mikroporozna struktura uočena je kod GAC-FeMn (996 m<br />² /g; 0,394 cm^{3 /}g). U poređenju sa ostalim&nbsp; sintetisanim&nbsp; sorbentima,&nbsp; Chit-FeMn&nbsp; je&nbsp; karakterisala&nbsp; najmanja specifična&nbsp; povr&scaron;ina&nbsp; i&nbsp; zapremina&nbsp; mezopora&nbsp; (1,99&nbsp; m<br />²/g;&nbsp; 0,014&nbsp; cm ³ /g).&nbsp; XRD analiza&nbsp; Fe-Mn&nbsp; binarnih&nbsp; oksida&nbsp; ukazala&nbsp; je&nbsp; da&nbsp; je&nbsp; fazna&nbsp; struktura&nbsp; sintetisanih Fe-Mn&nbsp; binarnih&nbsp; oksida&nbsp; slična&nbsp; ferihidratu&nbsp; dok&nbsp; je&nbsp; fazna&nbsp; struktura&nbsp; magnetnih materijala ukazala na prisustvo magemita.<br />Ispitivanja kinetike sorpcionog procesa ukazala su da je mehanizam sorpcije<br />As(III)&nbsp; i&nbsp; As(V)&nbsp; na&nbsp; sintetisanim&nbsp; sorbentima&nbsp; sloţena&nbsp; kombinacija&nbsp; povr&scaron;inske<br />hemisorpcije,&nbsp; koja&nbsp; se&nbsp; odvija&nbsp; kroz&nbsp; granični&nbsp; sloj&nbsp; čestica&nbsp; sorbenata&nbsp; i unutarčestične difuzije. Tome u prilog i&scaron;li su i rezultati FTIR analize kojima<br />je potvrđeno da se sorpcija arsena na sintetisanim sorbentima ostvaruje kroz<br />interakcije hidroksilnih grupa gvožđa prisutnih na povr&scaron;ini sorbenata i arsena.<br />Dodatno, pokazano je da se za razliku od sorpcije As(V), sorpcija As(III) na sorbentima&nbsp; koji&nbsp; pored&nbsp; oksida&nbsp; gvožđa&nbsp; sadrže&nbsp; i&nbsp; okside&nbsp; mangana&nbsp; (Fe-Mn binarni oksidi, Mag-FeMn, Mag-Mn,Chit-FeMn i GAC-FeMn) odvija u dva koraka. U prvom koraku As(III) se oksiduje do As(V), dok u drugom koraku, oksidovani&nbsp; As(V)&nbsp; mehanizmom&nbsp; ligandne&nbsp; izmene&nbsp; formira&nbsp; komplekse&nbsp; na povr&scaron;ini ovih sorbenata.<br />Afiniteti sorpcije Fe-Mn binarnih oksida (na osnovu K_d vrednosti)&nbsp; za As(III) opadali su u nizu Fe-Mn 3:1 &gt; Fe-Mn 1:1 &gt; Fe-Mn 6:1 &gt; Fe-Mn 9:1 odnosno kod&nbsp; As(V):&nbsp; Fe-Mn&nbsp; 6:1&nbsp; &gt;&nbsp; Fe-Mn&nbsp; 3:1&nbsp; &gt;&nbsp; Fe-Mn&nbsp; 9:1&nbsp; &gt;&nbsp; Fe-Mn&nbsp; 1:1.&nbsp; Kod magnetnih kompozita,&nbsp; najveća K_d vrednost za As(III) i As(V) ustanovljena je kod&nbsp; Mag-FeMn.&nbsp; Uop&scaron;teno,&nbsp; Kd<br />vrednosti&nbsp; za&nbsp; As(III),&nbsp; kod&nbsp; magnetnih kompozita,&nbsp; opadale&nbsp; su&nbsp; u&nbsp; nizu:&nbsp; Mag-FeMn&nbsp; &gt;&nbsp; Mag-Mn&nbsp; &gt;&nbsp; Mag&nbsp; &gt;&nbsp; Mag-Fe, Slično, afinitet sorbenata za As(V), opadao je na sledeći način: Mag-FeMn &gt; Mag&nbsp; &gt;&nbsp; Mag-Fe&nbsp; &gt;&nbsp; Mag-Mn.&nbsp; U&nbsp; poređenju&nbsp; sa&nbsp; neimpregniranim,&nbsp; K_d vrednosti bile su daleko veće kod obloţenih materijala, Chit-FeMn i GAC-FeMn, &scaron;to je ukazalo&nbsp; na&nbsp; značajan&nbsp; doprinos&nbsp; Fe-Mn&nbsp; binarnog&nbsp; oksida&nbsp; adsorpcionom kapacitetu neimpregniranih medija za As(III) i As(V). U&nbsp; odnosu&nbsp; na&nbsp; ostale&nbsp; ispitivane&nbsp; anjone,&nbsp; najveći&nbsp; uticaj&nbsp; na&nbsp; sorpciju&nbsp; oba&nbsp; oblika arsena&nbsp; na&nbsp; svim&nbsp; sintetisanim&nbsp; sorbentima&nbsp; uočen&nbsp; je&nbsp; kod&nbsp; fosfata,&nbsp; dok&nbsp; je&nbsp; uticaj nitrata i hlorida, u svim slučajevima bio bez značaja. Uticaj ispitivanih anjona na&nbsp; sorpciju&nbsp; As(III)&nbsp; i&nbsp; As(V)&nbsp; na&nbsp; Fe-Mn&nbsp; binarnim&nbsp; oksidima,&nbsp; magnetnim materijalima, Chit-FeMn kao i na sorpciju As(V) na GAC-FeMn, opadao je u nizu: fosfati &gt; silikati &gt; karbonati &gt; sulfati &gt; nitrati &gt; hloridi. Slično, uticaj ispitivanih&nbsp; anjona&nbsp; na&nbsp; sorpciju&nbsp; As(III)&nbsp; na&nbsp; GAC-FeMn&nbsp; je&nbsp; opadao&nbsp; na&nbsp; sledeći način: fosfati &gt; silikati &gt; sulfati &gt; karbonati &gt; nitrati &gt; hloridi.Primenom&nbsp; sme&scaron;e&nbsp; NaCl-NaOH-NaOCl&nbsp; odnosno&nbsp; primenom&nbsp; 0,1&nbsp; M&nbsp; i&nbsp; 0,5&nbsp; M&nbsp; rastvora NaOH, ustanovljeno je da se sintetisani sorbenti mogu jednostavno i&nbsp; efikasno&nbsp; regenerisati&nbsp; i&nbsp; vi&scaron;estruko&nbsp; primeniti,&nbsp; &scaron;to&nbsp; je&nbsp; od&nbsp; izuzetnog&nbsp; značaja&nbsp; sa ekolo&scaron;kog i ekonomskog aspekta.&nbsp; Najmanje smanjenje sorpcionog kapaciteta&nbsp; i za As(III) i za As(V), nakon pet ciklusa sorpcije -desorpcije, ustanovljeno je kod binarnog oksida sa Fe:Mn molskim odnosom 3:1 i Mag-FeMn.&nbsp; Na osnovu rezultata prikazanih u ovom radu, može se zaključiti da sintetisani sorbenti,&nbsp; Fe-Mn&nbsp; binarni&nbsp; oksidi&nbsp; i&nbsp; magnetni&nbsp; kompoziti,&nbsp; posebno&nbsp; Mag-FeMn, mogu&nbsp; biti&nbsp; efikasna&nbsp; i&nbsp; ekonomična&nbsp; alternativa&nbsp; skupim&nbsp; komercijalnim sorbentima&nbsp; i&nbsp; drugim&nbsp; sofisticiranim&nbsp; tehnologijama.&nbsp; Visok&nbsp; oksidacioni&nbsp; i sorpcioni kapacitet ovih&nbsp; materijala, koji obezbeđuje istovremeno uklanjanje&nbsp; oba oksidaciona oblika arsena daje veliku prednost ovim sorbentima i čini ih veoma&nbsp; atraktivnim&nbsp; i&nbsp; obećavajućim&nbsp; u&nbsp; tretmanu&nbsp; voda.&nbsp; Dodatni&nbsp; benefit<br />magnetnih&nbsp; sorbenata,&nbsp; pre&nbsp; svega&nbsp; Mag-FeMn,&nbsp; ogleda&nbsp; se&nbsp; u&nbsp; njegovoj jednostavnoj separaciji iz vodenog medijuma i recirkulaciji u sistemu. Glavne prednosti&nbsp; sintetisanih&nbsp; Chit-FeMn&nbsp; i&nbsp; GAC-FeMn,&nbsp; ogledaju&nbsp; se&nbsp; u&nbsp; mogućnosti&nbsp; njihove primene kao efikasne filtracione ispune.</p> / <p>The&nbsp; presence&nbsp; of&nbsp; inorganic&nbsp; arsenic&nbsp; in&nbsp; groundwater&nbsp; used&nbsp; for&nbsp; drinking&nbsp; water supply&nbsp; is&nbsp; a&nbsp; global&nbsp; problem.&nbsp; Different&nbsp; techniques&nbsp; such&nbsp; as&nbsp; oxidation, coagulation,&nbsp; adsorption,&nbsp; ion&nbsp; exchange,&nbsp; and&nbsp; membrane&nbsp; filtration&nbsp; have&nbsp; been developed&nbsp; and&nbsp; applied&nbsp; for&nbsp; arsenic&nbsp; removal&nbsp; from&nbsp; aqueous&nbsp; media.&nbsp; Among these&nbsp; technologies,&nbsp;&nbsp; adsorption&nbsp; is&nbsp; regarded&nbsp; as&nbsp; one&nbsp; of&nbsp; the&nbsp; most&nbsp; promising approaches to remove arsenic from water because of its high efficiency, low cost, simplicity of operation. Although many sorbents for arsenic removal are available on the market, there is still a need to identify and develop new&nbsp; lowcost&nbsp; sorbents which are highly effective in removing both oxidation states of arsenic, As(III) and As(V). This dissertation therefore presents the synthesis and&nbsp; characterization&nbsp; of&nbsp; ten&nbsp; new&nbsp; iron&nbsp; and&nbsp; manganese&nbsp; based&nbsp; sorbents specifically developed for effective As removal. The Fe- Mn binary oxides were prepared with Fe:Mn molar ratios of 1:1, 3:1,6:1 and 9:1, while four heterogeneous magnetic composites (Mag, Mag-Fe,Mag-Mn,&nbsp; Mag-FeMn)&nbsp; were&nbsp; synthesized&nbsp; by&nbsp; combining&nbsp; the&nbsp; heterogeneous nucleation&nbsp; technique&nbsp; with&nbsp; precipitation.&nbsp; The&nbsp; remaining&nbsp; two&nbsp; materials, Chit-FeMn&nbsp; and&nbsp; GAC-FeMn,&nbsp; were&nbsp; created&nbsp; by&nbsp; modifying&nbsp; the&nbsp; Chitosan&nbsp; and GAC&nbsp; biopolymers&nbsp; with&nbsp; Fe-Mn&nbsp; binary&nbsp;&nbsp; oxide&nbsp; (Chit-FeMn&nbsp; and&nbsp; GAC-FeMn).Multiple&nbsp; techniques&nbsp; were&nbsp; applied&nbsp; to&nbsp; determine&nbsp; the&nbsp; physical&nbsp; and&nbsp; chemical characteristics&nbsp; of&nbsp; the&nbsp; resulting&nbsp; sorbents&nbsp; (including&nbsp; SEM/EDS,&nbsp; XRD,&nbsp; FTIR and BET analyses). In order to establish which sorbents show&nbsp; the greatest promise for application during&nbsp; drinking&nbsp; water&nbsp; treatment,&nbsp; the&nbsp; sorption&nbsp; capacity&nbsp; of&nbsp; the&nbsp; sorbents,&nbsp; theAs(III)&nbsp; and&nbsp; As(V)&nbsp; sorption&nbsp; mechanisms,&nbsp; and&nbsp; the&nbsp; impact&nbsp; of&nbsp; various&nbsp; factors relevant to arsenic sorption, including the regeneration potential and the reuse potential of the sorbents, were all investigated in&nbsp; batch experiments. During the physical characterisation, the Fe-Mn binary oxides and magnetic materials&nbsp; were&nbsp; found&nbsp; to&nbsp; have&nbsp; relatively&nbsp; large&nbsp; specific&nbsp; surface&nbsp; areas (109-300 m 2 /g) and mesopore volumes (0.144-0.403 cm 3 /g).&nbsp; A large specific surface&nbsp; area&nbsp; and&nbsp; microporous&nbsp; structure&nbsp; was&nbsp; observed&nbsp; for&nbsp; GAC-FeMn&nbsp; (996 m 2 /g;&nbsp; 0.394&nbsp; cm 3 /g).&nbsp; In&nbsp; comparison&nbsp; with&nbsp; the&nbsp; other&nbsp; synthesized&nbsp; sorbents,&nbsp; Chit-FeMn has the smallest specific surface area and pore volume (1.99 m 2 /g; 0.014&nbsp; cm 3 /g).&nbsp; XRD&nbsp; analyses&nbsp; of&nbsp; the&nbsp; Fe-Mn&nbsp; binary&nbsp; oxides&nbsp; indicated&nbsp; that&nbsp; the phase&nbsp; structure&nbsp; of&nbsp; the&nbsp; synthesized&nbsp; Fe-Mn&nbsp; binary&nbsp; oxides&nbsp; was&nbsp; similar&nbsp; to ferrihydrate,&nbsp; while&nbsp; the&nbsp; phase&nbsp; structure&nbsp; of&nbsp; the&nbsp; magnetic&nbsp; materials&nbsp; showed&nbsp; a good agreement with the XRD diffractogram of maghemite. Investigations into As sorption process kinetics have shown that the sorption mechanism&nbsp; for&nbsp; both&nbsp; As(III)&nbsp; and&nbsp; As(V)&nbsp; on&nbsp; the&nbsp; synthesized&nbsp; sorbents&nbsp; is&nbsp; a combination&nbsp; of&nbsp; surface&nbsp; hemisorption,&nbsp; which&nbsp; takes&nbsp; place&nbsp; through&nbsp; the boundary&nbsp; layer&nbsp; of&nbsp; sorbent&nbsp; particles,&nbsp; and&nbsp; intracellular&nbsp; diffusion.&nbsp; The&nbsp; FTIR analyses&nbsp; confirmed&nbsp; that&nbsp; arsenic&nbsp; sorption&nbsp; was&nbsp; accomplished&nbsp; through&nbsp; the interactions&nbsp; of&nbsp; the&nbsp; hydroxyl&nbsp; groups&nbsp; of&nbsp; iron&nbsp; present&nbsp; on&nbsp; the&nbsp; surface&nbsp; of&nbsp; the sorbents and arsenic. In contrast to the sorption of As(V), it was also shown that&nbsp; As(III)&nbsp; sorption&nbsp; onto&nbsp; sorbents&nbsp; containing&nbsp; manganese&nbsp; oxides&nbsp; (Fe-Mn binary&nbsp; oxides,&nbsp; Mag-FeMn,&nbsp; Mag-Mn,&nbsp; Chit-FeMn&nbsp; and&nbsp; GAC&nbsp; -FeMn)&nbsp; takes place in two steps. In the first step As(III) is oxidized to As(V), while in the second&nbsp; step,&nbsp; the&nbsp; oxidized&nbsp; As(V)&nbsp; forms&nbsp; complexes&nbsp; on&nbsp; the&nbsp; surface&nbsp; of&nbsp; the sorbents via ligand exchange. The&nbsp; Fe-Mn&nbsp; binary&nbsp; oxide&nbsp; sorption&nbsp; capacities&nbsp; (expressed&nbsp; as&nbsp; Kd values)&nbsp; for As(III)&nbsp;&nbsp; followed the trend Fe-Mn 3:1 &gt; Fe-Mn 1:1 &gt; Fe-Mn 6:1 &gt; Fe-Mn 9:1, whereas the&nbsp; As(V) trend was Fe-Mn 6:1 &gt; Fe-Mn 3:1 &gt; Fe-Mn 9:1 &gt; Fe-Mn 1:1. In the magnetic&nbsp; composites, the largest&nbsp; Kd value for As(III) and As(V) was&nbsp; obtained&nbsp; for&nbsp; Mag-FeMn.&nbsp; Generally,&nbsp; the&nbsp; Kd values&nbsp; for&nbsp; As(III)&nbsp; in&nbsp; the magnetic composites decreased in the series: Mag-FeMn &gt; Mag-Mn &gt; Mag &gt; Mag-Fe.&nbsp; Similarly,&nbsp; the&nbsp; affinity&nbsp; of&nbsp; the&nbsp; sorbents&nbsp; for&nbsp; As(V)&nbsp; was&nbsp; as&nbsp; follows: Mag-FeMn&nbsp; &gt;&nbsp; Mag&nbsp; &gt;&nbsp; Mag-Fe&nbsp; &gt;&nbsp; Mag- Mn.&nbsp; In&nbsp; comparison&nbsp; to&nbsp; the&nbsp; nonimpregnated&nbsp; materials,&nbsp; the&nbsp; Kd values&nbsp; were&nbsp; much&nbsp; higher&nbsp; for&nbsp; the&nbsp;&nbsp; boated materials,&nbsp; Chit-FeMn&nbsp; and&nbsp; GAC-FeMn,&nbsp; demonstrating&nbsp; the&nbsp; significant advantage&nbsp; Fe-Mn&nbsp; binary&nbsp; oxides&nbsp; provide&nbsp; in&nbsp; increasing&nbsp; As(III)&nbsp; and&nbsp; As(V)&nbsp; adsorption capacities. One&nbsp; of&nbsp; the&nbsp; most&nbsp; problematic&nbsp; limiting&nbsp; factors&nbsp; in&nbsp; applying&nbsp; adsorption technologies during drinking water treatment is the presence of other water constituents which interfere with the adsorption process.&nbsp; Investigations into the inhibitory effect of competive anions on the adsorption of both forms of arsenic&nbsp; revealed&nbsp; that&nbsp; phosphates&nbsp; were&nbsp; the&nbsp; worst&nbsp; offenders&nbsp; in&nbsp; terms&nbsp; ofreducing&nbsp; the&nbsp; arsenic&nbsp; removal&nbsp; efficacy&nbsp; of&nbsp; sorbents&nbsp; investigated.&nbsp; From&nbsp; the largest&nbsp; to&nbsp; the&nbsp; smallest&nbsp; negative&nbsp; influence&nbsp; of&nbsp; the&nbsp; anions&nbsp; investigated,&nbsp; for As(III)&nbsp; and&nbsp; As(V)&nbsp; adsorption&nbsp; on&nbsp; Fe-Mn&nbsp; binary&nbsp; oxides,&nbsp; magnetic&nbsp; materials and Chit-FeMn, as well as As(V) adsorption on GAC-FeMn, the order was: phosphates &gt; silicates &gt; carbonates &gt; sulfates &gt; nitrates &gt; chlorides, with the presence&nbsp; of&nbsp; the&nbsp; latter&nbsp; two&nbsp; anions&nbsp; proving&nbsp; almost&nbsp; irrelevant&nbsp; to&nbsp; the&nbsp; As adsorption&nbsp; process.&nbsp; Similarly,&nbsp; the&nbsp; negative&nbsp; influence&nbsp; of&nbsp; anions&nbsp; on&nbsp; As(III) sorption on GAC-FeMn was: phosphates &gt; silicates &gt; sulphates &gt; carbonates &gt; nitrates &gt; chlorides. Another&nbsp; issue&nbsp; with&nbsp; applying&nbsp; adsorption&nbsp; in&nbsp; real&nbsp; treatment&nbsp; conditions&nbsp; is&nbsp; the need to regularly&nbsp; regenerate and/or replace the spent sorbent. In this work, a simple&nbsp; and&nbsp; efficient&nbsp; process&nbsp; for&nbsp; sorbent&nbsp;&nbsp; rfegeneration&nbsp; is&nbsp; demonstrated.&nbsp; This regeneration&nbsp; process&nbsp; can&nbsp; be&nbsp; applied&nbsp; to&nbsp; the&nbsp; sorbents&nbsp; investigated&nbsp; multiple times, and uses an NaCl-NaOH-NaOCl mixture, or 0.1 M and 0.5 M NaOH solutions.&nbsp; This&nbsp; finding&nbsp; is&nbsp; of&nbsp; great&nbsp; importance&nbsp; from&nbsp; an&nbsp; ecological&nbsp; and economic point of view. The minimum reduction in the sorption capacity for both As(III) and As(V), after five sorption-regeneration cycles, was found in&nbsp; the&nbsp; binary&nbsp; oxide&nbsp; with&nbsp; a&nbsp; 3:1&nbsp; Fe:Mn&nbsp; molar&nbsp; ratio&nbsp; and&nbsp; Mag-FeMn.&nbsp; Arsenic sorption&nbsp; behaviour&nbsp; was&nbsp; also&nbsp; investigated&nbsp; using&nbsp; real&nbsp; groundwater&nbsp; samples, with the results demonstrating the great potential of 3:1 Fe-Mn binary oxide and Mag- FeMn. However, Chit-FeMn and GAC-FeMn were less effective at adsorbing As from the groundwater samples.Based on the results presented in this dissertation, it can&nbsp; be concluded that the synthesized&nbsp; sorbents,&nbsp; especially&nbsp; the&nbsp; Fe-Mn&nbsp; binary&nbsp; oxides&nbsp; and&nbsp; magnetic composites,&nbsp; and&nbsp; Mag-FeMn&nbsp; in&nbsp; particular,&nbsp; can&nbsp; be&nbsp; efficient&nbsp; and&nbsp; economical alternatives&nbsp; to&nbsp; expensive&nbsp; commercial&nbsp; sorbents&nbsp; and&nbsp; other&nbsp; sophisticated&nbsp; As removal&nbsp; technologies.&nbsp; The&nbsp; high&nbsp; oxidation&nbsp; and&nbsp; sorption&nbsp; capacity &nbsp; of&nbsp; these materials,&nbsp; which&nbsp; ensure&nbsp; the&nbsp; simultaneous&nbsp; removal&nbsp; of&nbsp; arsenic&nbsp; with&nbsp; both oxidation states, is a large advantage for these sorbents and makes them very attractive&nbsp; and&nbsp; promising&nbsp; for&nbsp; application&nbsp; in&nbsp; drinking&nbsp; water&nbsp; treatment.&nbsp; An additional&nbsp; benefit of the magnetic sorbents, primarily Mag-FeMn, is the ease with&nbsp; which&nbsp; they&nbsp; may&nbsp; be&nbsp; separated&nbsp; from&nbsp; the&nbsp; aqueous&nbsp; medium,&nbsp; allowing&nbsp; for simple&nbsp; recirculation within a system. Similarly,&nbsp; the main advantages of&nbsp; the synthesized Chit- FeMn and GAC-FeMn are reflected in their application as effective filtration media.</p>