Remediation of heavy metals from industrial effluents and ground water sources poses a significant challenge. Hexavalent chromium is one such heavy metal, prevalent in industrial wastewaters, which has been proven to be toxic to humans and other living organisms. Most of the conventional methods available for dealing with chromium are either cost prohibitive or generate secondary effluents which are difficult to deal with. The idea of bioremediation has gained much momentum over the last few decades because of its potential low cost and minimum impact on the environment. This study explored the potential for hexavalent chromium bioremediation using a synthetic cationic biopolymer alpha-poly-l-lysine (alpha-PLL) as a biosorbent. In the present research work, equilibrium batch studies were performed in a specially designed dialysis apparatus to obtain preliminary information about the adsorption capacity of the polymer. Metal uptake by the polymer was found to be maximum when the pH of chromium solution (pH 4.6) and that of poly-lysine (pH 5.7) was not changed at the beginning of the experiment. Applying the Langmuir adsorption isotherm model showed that alpha-PLL has a maximum uptake capacity of 42.2 microgram Cr/mg alpha-PLL, and a binding constant of 1.2 microgram/mL +/- 10%. The metal uptake performance of the polymer was also evaluated in a Polymer Enhanced Diafiltration (PEDF) system. The polymer-metal complex was retained and concentrated by the PEDF set up using a tangential flow filtration membrane, while the clean filtrate flowed through. When 3.4 L of 10 mg/L chromium solution in the Cr2O72- form was processed using 300 mL of 2 gm/L PLL, the concentration of chromium in the permeate reached a maximum of 0.79 mg/L. When 30 mg/L chromium solution was used, 2 L could be processed using 300 mL of 2gm/L PLL, and 7.8 mg/L chromium could be detected in the permeate in the end.

[pt] Os efluentes líquidos contaminados com metais pesados é uma ameaça ambiental, os íons metálicos tóxicos encontram-se dissolvidos, atingindo eventualmente o topo da cadeia alimentar e assim, tornando-se um fator de risco para a saúde humana e ambiente. Diversos métodos de tratamento de efluentes como precipitação química, coagulação, floculação, flotação, troca iônica e filtração são empregados para remoção dos metais pesados. Entretanto, estes possuem algumas desvantagens quando empregados para tratamento de grandes volumes de efluentes líquidos com baixas concentrações de metais. Neste trabalho foi avaliada a cepa bacteriana Rhodococcus opacus como um potencial biossorvente para a remoção de mercúrio de soluções aquosas através de biossorção. O valor de pH adequado para a biossorção foi em torno de 5 para o metal. Os dados correspondentes à capacidade de captação do Rhodococcus opacus em função da concentração do mercúrio foi bem ajustada ao modelo de Freundlich. A capacidade de captação máxima obtida foi de 37,9 mg.g-1 para o mercúrio, equivalente a uma remoção de 73,42 %. A cinética de biossorção para o mercúrio foi modelada pela equação de pseudo-segunda ordem. Foram avaliadas também as propriedades superficiais dos microorganismos antes e após a interação dos metais para poder determinar os possíveis mecanismos implicados na biossorção mediante medições de espectroscopia de infravermelho. Os resultados apresentados mostram que o Rhodococcus opacus apresenta características adequadas no que tange a flotação biossortiva para remoção de metais. / [en] Heavy metals presence in wastewaters is a common environmental threat, since these toxic metal ions are dissolved, eventually reaching the top of the food chain and thus become a risk factor to human health and the environment. Mercury is considered a pollutant of high risk been regulated by USEPA (United States Environmental Protection Agency). The concern regarding pollution by mercury emerges of the problems to health caused for exposition to methyl mercury found in the aquatic water and foods in normal conditions. Several methods of effluent treatment like chemical precipitation, coagulation, flocculation, flotation, ion exchange, filtration are used to remove heavy metals. These methods have some drawbacks when used for treating large volumes of wastewater with low concentration of the metal. In this study we evaluated the bacterial strain Rhodococcus opacus as a potential biosorbent for mercury removal from aqueous solutions through biosorption. The pH value suitable for the biosorption of the metal was around 5. The data corresponding to the uptake capacity of Rhodococcus opacus depending on the concentration of mercury was well adjusted to the Freundlich model. The maximum uptake capacity was about: 37.9 mg.g-1 for mercury equivalent to a removal of 73.42%. The kinetics of mercury biosorption was representated by a equation of pseudo-second order. We also evaluated the surface characteristics of the microorganism before and after the interaction of metals in order to determine the possible mechanisms involved in biosorption by measurements of infrared spectroscopy. The results demonstrated that Rhodococcus opacus shows good performance as biosorbent for bioaccumulation of Hg (II).

Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-09-29T12:32:06Z No. of bitstreams: 1 Augusto Cezar Dotta Filho - 2017.pdf: 2224139 bytes, checksum: 163d447d5817cd0b75af08b225f112da (MD5) / Approved for entry into archive by Marlucy Farias Medeiros (marlucy.farias@unipampa.edu.br) on 2017-09-29T16:24:22Z (GMT) No. of bitstreams: 1 Augusto Cezar Dotta Filho - 2017.pdf: 2224139 bytes, checksum: 163d447d5817cd0b75af08b225f112da (MD5) / Made available in DSpace on 2017-09-29T16:24:22Z (GMT). No. of bitstreams: 1 Augusto Cezar Dotta Filho - 2017.pdf: 2224139 bytes, checksum: 163d447d5817cd0b75af08b225f112da (MD5) Previous issue date: 2017-03-17 / No presente trabalho foi empregado o capim-annoni (CA) in natura como biossorvente para remoção do corante Violeta de Metila 10B (VM 10B) de solução aquosa. O capim-annoni foi preparado e caracterizado utilizando as seguintes técnicas analíticas: Microscopia Eletrônica de Varredura (MEV), Espectroscopia na Região do Infravermelho (ATR-FTIR), Método B.E.T (Brunauer, Emmet e Teller) e B.J.H (Barret, Joyner e Halenda), Extração Soxhlet e Método de Boehm. A influência dos parâmetros concentração mássica de biossorvente, pH da solução, tempo de contato e concentração inicial do corante, velocidade de agitação do sistema e temperatura foram usados para investigar as condições experimentais ideiais para adsorção entre corante/biossorvente. Os resultados mostram que com 150,0 mg de CA, pH da solução em 8,0, tempo de contato de 180 min. e velocidade de agitação de 100 rpm obteve-se condições mais favoráveis de adsorção. A cinética de adsorção do VM 10B no CA foi investigada utilizando os modelos cinéticos clássicos de Pseudoprimeira Ordem e Pseudossegunda Ordem. O Modelo de Pseudossegunda Ordem foi o que forneceu melhor ajuste aos dados experimentais. O Modelo de Isoterma de Sips foi o mais adequado para descrever o mecanismo de adsorção apresentando os menores valores para o parâmetro estatístico Função erro (Ferror) e os valores mais próximos da unidade para o coeficiente de determinação (R2). A capacidade máxima de adsorção obtido através do modelo de Sips foi de 76, 20 mg g-1 em temperatura de 60 ºC. Os Estudos de Dessorção do VM 10B no CA mostram que é possível regenerar o biossorvente de forma satisfatória empregando ácido acético 1,0 mol L-1 como eluente. Estudos termodinâmicos mostram que a adsorção do VM 10B no CA é um processo endotérmico, espontâneo e regido por um mecanismo de Fisissorção. A aplicação do CA na remoção do VM 10B de efluentes têxteis simulados foi satisfatória mostrando que o mesmo pode ser utilizado no tratamento de águas industriais coloridas. / In the present work South African Lovegrass (CA) was used in natura as biosorbent in order to remove the dye Methyl Violet 10B (VM 10B) of the aqueous solution. The following analytical techniques were used to prepare and characterized the CA in question: Scanning Electron Microscopy (SEM), Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), B.E.T Method (Brunauer, Emmet and Teller) and B.J.H (Barret, Joyner and Halenda), Soxhlet Extraction and Boehm Method. To investigate the ideal experimental conditions for adsorption between dye and biosorbent, the influence of the biosorbent mass concentration, pH solution, contact time and initial dye concentration, stirring speed and temperature were used. Results show that with 150.0 mg CA, pH solution 8.0, contact time of 180 min. and stirring speed at100 rpm presented adsorption conditions that were more favorable. The adsorption kinetic of VM 10B in CA was investigated using the classical kinetic models of pseudo-first and pseudo-second-orders. The pseudo-second-order was found to provide the best adjustment to the experimental data. Sips Isothermal Model has proven to be the most adequate to describe the adsorption mechanism presenting the smallest values for the statistical parameter Error Function (erf) and the closest values of the unit for the coefficient of determination (R2). The maximum adsorption capacity obtained through the Sips model was 76.20 mg g -1 at 60 °C. Desorption Studies of VM 10B in CA show that it is possible to regenerate the biosorbent satisfactorily using 1.0 mol L-1 acetic acid as an eluent. Thermodynamic studies show that adsorption of VM 10B in CA is an endothermic process, spontaneous and commanded by a physical adsorption mechanism. The application of CA in the removal of the VM 10B from simulated textile effluents was satisfactory showing that it can be used to treat colored industrial waters.

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2017-10-19T18:08:01Z No. of bitstreams: 1 PDF - Érica Bento Sarmento.pdf: 13879047 bytes, checksum: 67a1b7254248598e56e94504acddb9b4 (MD5) / Made available in DSpace on 2017-10-19T18:08:01Z (GMT). No. of bitstreams: 1 PDF - Érica Bento Sarmento.pdf: 13879047 bytes, checksum: 67a1b7254248598e56e94504acddb9b4 (MD5) Previous issue date: 2017-08-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / One of the most worrisome and frequent pollutants is heavy metals, which are highly toxic and harmful, making water unfeasible; alternatively, various treatment techniques have been proposed for there moval of metals in water. The adsorption process, besides having a high efficiency in there moval of metals, still has as an advantage the ease of operation and the possibility of use and integral use ofcrops, by-products / wastes that are considered trash by a good part of society and that in the majority of times they only pile up in dumps and compromise the life of land fills. This work aimedat the production of a powder obtained from the drying of the mesocarp of the "greencoconut" and to evaluate its use as adsorbent of copperions (Cu^2+ ) in industrial effluents. For the study of the kinetic data required in the drying study, anairrefurbishmentoven with air -1 flow velocity of 1.0 m.s wasused, with a temperature of 70 ± 3 ° C. The kinetic model that presented the best ad justment in the drying process was Page Modified (R² = 0.9999). The amount of Cu^2+ adsorbed in the adsorption process using the mesocarp powder presented more satisfactory results with removal in the 99% range for the tests with activated material. Among the isotherms adjusted to the experimental data, the correlation coefficients indicate that the Langmuir model (> 0.99) is the best fit for Cu^2+ adsorption, characterizing that the adsorption occurs in monolayer. It can be concluded that the 'greencoconut' mesocarppowderunderthe 'in natura' and activated conditions proved to bean attractive adsorbent, with great adsorptive potential, making it an ideal biosorbent for Cu^2+ adsorption process. / Um dos poluentes mais preocupantes e frequentes são os metais pesados, altamente tóxicos e nocivos, inviabilizam a utilização de águas, como alternativa, várias técnicas de tratamento têm sido propostas para remoção de metais em águas. O processo de adsorção além de apresentar uma alta eficiência na remoção de metais, ainda apresenta como vantagem a facilidade de operação e a possibilidade de utilização e aproveitamento integral de culturas, subprodutos/resíduos que são considerados lixo por boa parte da sociedade e que na maioria das vezes só empilham em lixões e comprometem a vida útil de aterros. Este trabalho teve como objetivo a Produção de um pó obtido a partir da secagem do mesocarpo do “coco verde” e avaliar a sua utilização como adsorvente de íons cobre (Cu^2+ ) em efluentes industriais. Para o levantamento dos dados cinéticos necessários no estudo da secagem, usou-se estufa de renovação de ar -1 com velocidade do fluxo de ar de 1,0 m.s com temperatura a 70 ± 3 °C. O modelo cinético que apresentou melhor ajuste no processo de secagem foi o de Page Modificado 2+ (R² = 0,9998). A quantidade de Cu adsorvida no processo de adsorção utilizando o pó do mesocarpo apresentou resultados mais satisfatórios com remoção na faixa de 99% para os ensaios com material ativado. Entre as isotermas ajustadas aos dados experimentais, os coeficientes de correlação indicam que o modelo de Langmuir (> 0,99), é o que melhor se ajusta na adsorção de Cu^2+ , caracterizando que a adsorção ocorre em monocamada. Pode-se concluir que o pó de mesocarpo de ‘coco verde’ nas condições ‘in natura’ e ativado mostrou-se ser um adsorvente atrativo, e de grande potencial adsortivo, tornando - o um biossorvente ideal para processo de adsorção de Cu^2+ .

Ces travaux ont consisté à développer un procédé de traitement biologique des eaux contaminées en produits phytosanitaires (PF) issues du lavage des matériels de pulvérisation de PF. Ce procédé s’appuie surl’inoculation d’une culture bactérienne mixte sélectionnée et d’un matériau sorbant constitué de rafles de maïs broyées.Tout d’abord, un mélange modèle de PF,constitué de 6 herbicides, 3 fongicides et 1 insecticide, a été créé. Après avoir mis au point la production de l’inoculum en présence de ce mélange et étudié les propriétés sorbantes des rafles de maïs, les paramètres de traitement ont été définis à petite échelle de laboratoire et validés en réacteur.Finalement, le procédé développé est un traitement en réacteur batch séquentiel de 28 jours qui permet de réduire de plus de 50 % la masse initiale des PF du mélange modèle. Malgré la réduction des teneurs en PF, la phytotoxicité due aux résidus d’herbicides des effluents traités est encore trop élévée et ne permet pas de valider l’épandage sur un lit planté de roseaux comme post-traitement de la fraction liquide. / Aim of this work was to treat effluentsobtained from rinsing pesticide (PF) spraying equipments by developing biological treatment process into bioreactor with selected mixed bacterial culture and adsorption support consisting of crushed corn cobs. First, a model PF mixture was designed to represent agriculturaleffluents at watershed scale. This mixture was composed by 6 herbicides, 3 fungicides and 1 insecticide. Then, inoculum production under PF pressure was developed and sorption properties of corn cobswere investigated. Process parameters were defined at small-scale laboratory and validated into bioreactors. Thus, developed processwas a28 days sequential batch reactortreatment, which reduced more than 50% of molecules weight of model mixture.Despite of this process significantely reduced treated effluents PF contents, remaining phytotoxicity due to herbicide residues failed validation of their post-treatment on a bed planted with reeds.

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2018-10-29T23:59:53Z No. of bitstreams: 1 Gessica_Wernke_2016.pdf: 922626 bytes, checksum: 30a185f73d96f9bfc6546fd05ef03857 (MD5) / Made available in DSpace on 2018-10-29T23:59:54Z (GMT). No. of bitstreams: 1 Gessica_Wernke_2016.pdf: 922626 bytes, checksum: 30a185f73d96f9bfc6546fd05ef03857 (MD5) Previous issue date: 2016-03-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This study aims to evaluate the efficiency of Moringa oleifera as bark biosorbent to remove Diuron® herbicide, batch and fixed bed column. The characterization of biosorbent was performed by spectroscopy method infrared Fourier transform (FTIR), scanning electron microscopy (MEV) and textural properties by the BET method before and after biosorption process in fixed bed column. For batch systems the evaluated experimental conditions were biosorbent mass, particle size, pH, temperature and stirring speed. From studies in batch experimental conditions were determined for study in a fixed bed column, such experimental conditions were the amount of mass of the biosorbent (0,750, 1,5 and 3 g), concentration of the adsorvate (5; 10; 17 , 20 and 33 mg L- 1), feed flow (1, 2 and 3 ml min-1) and pH (4, 7 and 10). The results biosorption in a fixed bed column had a higher percentage removal in low- flow operating conditions (47,44 %) , larger bed height (50,55%), 5 mg L- 1 (47,07 %) and pH 7 (55,10 %). In the evaluation of the biosorbent regeneration capacity were used the best experimental conditions obtained in the study in a fixed bed column, which was used as solvent ultra-pure water. With study analysis biosorption/desorption was observed that there was a complete regeneration of the biosorbent after six cycles. To describe the experimental data of breakthrough curves obtained in a fixed bed column, the mathematical models available in the literature were used. The most satisfactory model that represented the initial process of experimental data was the internal resistance can be regarded as limiting mass transfer step the biosorption process Diuron® herbicide. / Este trabalho visa avaliar a eficiência da casca da Moringa oleifera como biossorvente para remoção do herbicida Diuron®, em batelada e em coluna de leito fixo. A caracterização do biossorvente foi realizada pelo método de espectroscopia no infravermelho com transformada de Fourier (FTIR), microscopia eletrônica de varredura (MEV) e as propriedades texturais pelo método BET antes e após o processo de biossorção em coluna de leito fixo. Para o sistema em batelada as condições experimentais avaliadas foram de massa de biossorvente, granulometria, pH, temperatura e velocidade de agitação. A partir dos estudos em batelada foram determinadas as condições experimentais para o estudo em coluna de leito fixo, tais condições experimentais foram a quantidade de massa do biossorvente (0,750, 1,5 e 3 g), concentração do adsorvato (5; 10; 17; 20 e 33 mg L-1), vazões de alimentação (1, 2 e 3 mL min-1) e pH (4, 7 e 10). Os resultados de biossorção em coluna de leito fixo apresentaram uma maior porcentagem de remoção nas condições operacionais de menor vazão (47,44%), maior altura de leito (50,55%), concentração de 5 mg L-1 (47,07%) e pH 7 (55,10%). Na avaliação da capacidade de regeneração do biossorvente foram utilizadas as melhores condições experimentais obtidas no estudo em coluna de leito fixo, na qual foi utilizada como solvente a água ultra-pura. Com a análise do estudo de biossorção/dessorção, observou-se que houve uma completa regeneração do biossorvente após seis ciclos. Para descrever os dados experimentais das curvas de ruptura obtidos em coluna de leito fixo, foram utilizados os modelos matemáticos disponíveis na literatura. O modelo mais satisfatório que representou o processo inicial dos dados experimentais foi a resistência interna, podendo ser considerado como a etapa de transferência de massa limitante ao processo de biossorção do herbicida Diuron®.

D. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology. / Trivalent arsenic (As(III)) and hexavalent chromium (Cr(VI)) toxicity have necessitated a great deal of research into the remediation of contaminated water. The techniques applied including oxidation, coagulation-flocculation and ion exchange have suffered drawbacks due to the high cost of materials and equipment, complex operations and secondary pollution among others. Adsorption, however, remains a cost-effective solution in the remediation of contaminated water. The use of biosorbent materials further lowers the cost of the adsorption process and improves its eco-friendliness. These biomaterials, however, suffer some drawbacks as poor porosity, low adsorption capacities and mechanical strength thus require modifications to improve their applicability as biosorbents. In this work pine cone powder, a waste from pine trees, was used as a biosorbent for the removal of As(III) and Cr(VI) from water. The powder was pre-treated with Fenton’s reagent to oxidize some of the functional groups and provide more binding sites. Iron oxide magnetic nanoparticles (magnetite) were incorporated into the pine cone matrix to form a magnetic composite with higher heavy metal affinity. The magnetite nanoparticles were also doped with manganese to improve their redox capacities and aid in the oxidation of the toxic As(III) to the less toxic As(V) and allow for improved binding. The adsorbents used in the study were therefore named as Fenton’s treated pine cone powder (FTP), pine cone -magnetite composite (FTP-MNP), magnetite nanoparticles (MNP), manganese doped magnetite nanoparticles (Mn MNP) and manganese doped pine cone-magnetite composite (Mn FTP-MNP). The prepared materials were fully characterized, and the adsorption process was optimized for both As(III) and Cr(VI) removal from aqueous solution. After modification the surface area of the particles increased in the order Mn MNP>MNP>Mn FTP-MNP>FTP-MNP>FTP. Surface and Xray analysis confirmed the formation of magnetite by the presence of both ferric and ferrous ion states on the surface and characteristic diffraction peaks for magnetite. The adsorption data was fitted into isotherm and kinetic models and the nature of adsorption was determined from the thermodynamic and kinetic parameters. Equilibrium studies indicated that the adsorption followed Langmuir isotherm for all adsorbents and was thus monolayer in nature, further analysis indicated that chemisorption was the predominant type of adsorption with ion exchange being the predominant mechanism of adsorption. Spent adsorbents were tested for reusability and displayed excellent adsorption capacities when used for up to three times. Adsorption mechanism was evaluated using characterization techniques and the ion-exchange mechanism inferred from thermodynamic data was confirmed spectroscopically with redox reactions aiding in the removal of the pollutants from water. The introduction of competing anions in solution, lowered the adsorption efficiency of both arsenic and chromium on the adsorbent indicating that there was competition for adsorption sites.

[pt] A poluição por metais pesados vem se tornando um sério problema ambiental. O uso de biomassas como material sorvente para a destoxificação de efluentes industria is contendo metais aparece como uma alternativa promissora às tecnologias existentes. O objetivo desta dissertação foi determinar a capacidade de adsorção da casca de coco (Cocos nucifera) para diferentes metais pesados. No processo de biossorção foram ava liados o pH da solução, a concentração inicial dos íons metálicos, o tamanho de partícula e a cinética do processo. As características da superfície da casca de coco foram investigadas utilizando medições de potencial zeta e análises com microscópio eletrônico de varredura. Obtiveram-se altas percentagens de remoção para o Cd, Cr(III) e Cr(VI) dentre as seis espécies metálicas estudadas (As(V), Cd, Cr(III), Cr(VI), Ni e Zn). Os valores ótimos de pH utilizados foram de 7 para o cádmio e cromo (III) e de 2 para o cromo (VI). Em concentrações inicias inferiores a 100 mg/L foram obtidas percentagens de remoção superiores a 95%, 85% e 80% para o cádmio, cromo (III) e cromo (VI), respectivamente. Em concentrações inicias menores que 1000 mg/L, a percentagem de remoção para o cádmio e o cromo (III) foi de 80% e 85%, respectivamente. Foram utilizados os modelos de Langmuir e Freundlich para avaliar a capacidade de adsorção de metais pesados pela casca de coco. O modelo de Langmuir mostrou-se mais adequado para o cádmio e o cromo (VI), enquanto que para o cromo (III) o modelo de Freundlich foi o mais adequado. A cinética do processo de biossorção foi estudada para o cádmio mediante as análises integral e diferencial. Foi observado que o processo de biossorção de cádmio por casca de coco verde obedece a um modelo de pseudo-segunda ordem. Os resultados apresentados mostram que a casca de coco apresenta as características apropriadas para o processo de biossorção de cádmio, cromo (III) e cromo (VI) e que pode ser utilizada como uma alternativa aos processos clássicos de destoxificação de efluentes. / [en] Heavy metal pollution has become one of the most serious problems today, and the use of organic material biomass for the detoxification of industrial effluents for environmental protection offers a potential alternative to existing trea tment technologies. The aim of this work was determined the biosorption capacity of coconut fibers (Cocos nucifera) for different heavy metals. The effect of pH, initial concentration, size of particle and kinetics were studied. The characteristics of the surface of coconut fibers had been investigated using measurements of potential zeta and analyses with scanning electron microscope. The removal was found to be higher for cadmium, chromium (III) e chromium (VI) among the 6 metallic species studied (As, Cd, Cr (III), Cr (VI), Ni e Zn). The values of pH used were 7 for cadmium and chromium (III) and of 2 for chromium (VI). For cadmium, chromium (III) and chromium (VI), with an initial metal concentration lower than 100 mg/L, removal rates of 95%, 85% and 80% respectively had been observed. For cadmium and chromium (III), with an initial concentration lower than 1000 mg/L, removal rates of 80% and 85% respectively were found. The adsorption capacity of coconut fibers for heavy metals had been evaluated using Langmuir and Freundlich adsorption isotherms. The Langmuir´s model gave best results for cadmium and chromium (VI) and Freundlich´s model for chromium (III). The kinetics of the process was studied just for cadmium, because it presented the best removal rates. The kinetics study showed that the biosorption process followed a pseudo second order model. This suggests that coconut fibers represent a good option for biosorption process and can be used as an alternative to the classical technologies for effluent decontamination.

<p>U disertaciji je ispitana mogucnost kori&scaron;cenja<br />izluženih rezanaca &scaron;ecerne repe za adsorpciju<br />jona bakra u koloni sa nepokretnim<br />slojem. Eksperimenti su izvedeni primenom<br />Boks-Benkenovog eksperimentalnog dizajna<br />na tri nivoa sa tri promenljive: koncentracija<br />napojnog rastvora (50-150 mgL^-1), masa<br />adsorbenta (8-12 g) i pH napojnog rastvora<br />(4,0-5,0). Dobijene prevojne krive su<br />fitovane uobicajenim empirijskim modelima,<br />Boart-Adamsovim i modelom doza-odziv.<br />Na osnovu uocene asimetrije prevojne<br />krive, predložen je novi matematicki model.<br />Novi model predlaže prevojnu krivu koja<br />se sastoji od dva dela, koji u zbiru daju<br />kumulativnu krivu koja dosledno pokriva<br />uocenu asimetriju. Uzimajuci u obzir najnižu<br />prosecnu sumu kvadrata odstupanja, SSer<br />(3,610^-3) i najvi&scaron;u prosecnu vrednost<br />koeficijenta determinacije, R² (0,9989),<br />novi model je pokazao najbolje fitovanje<br />eksperimentalnih podataka, u poreenju sa<br />uobicajeno kori&scaron;cenim modelima adsorpcije<br />u koloni. RSM i ANN modelovanje je dalje<br />kori&scaron;ceno za evaluaciju procesnih parametara<br />i optimizaciju procesa. Najznacajnija<br />nezavisno promenljiva velicina, koja ispoljava<br />negativan uticaj na odabrani odziv (kriticno<br />vreme), bila je koncentracija napojnog<br />rastvora, dok je masa adsorbenta ispoljila<br />slabiji i pozitivan uticaj na odziv. Optimizacijom procesa metodom ANN je<br />utvreno da se najveca vrednost kriticnog<br />vremena (341,4 min) postiže pri sledecim<br />uslovima: C0=50 mgL^-1, ma=12 g and pH<br />4,53, dok metoda RSM smatra pH vrednost<br />faktorom koji nema znacaja po odziv u<br />ispitivanom opsegu, i postiže maksimalno<br />kriticno vreme od 314,8 min, pri istim ostalim<br />uslovima kao i ANN.<br />Iskori&scaron;ceni adsorbent, zasicen jonima bakra,<br />je zatim spaljen i dobijeni pepeo je iskori&scaron;cen<br />kao punilo u proizvodnji gume. Proizvedena<br />su cetiri uzorka gume sa razlicitim sadržajem<br />pepela. Pracen je proces vulkanizacije<br />gume, odreena su mehanicka svojstva<br />gotovog proizvoda i izvreno je poreenje<br />dobijenih rezultata izmeu uzoraka sa i<br />bez dodatka pepela. Rezultati su pokazali<br />da dodatak pepela u strukturu gume ne<br />utice znacajno na njene mehanicke osobine.<br />Meutim, povecanje sadržaja pepela u gumi<br />dovodi do povecanja energije aktivacije<br />procesa vulkanizacije, &scaron;to se može smatrati<br />unapreenjem procesa proizvodnje gume u<br />slucaju proizvoda velikih dimenzija. Na<br />kraju, ispitano je izluživanje bakra iz gotovih<br />proizvoda od gume. Rezultti su pokazali da je<br />kolicina bakra izluženog u vodu veoma niska,<br />reda velicine 0,001%, &scaron;to se može smatrati<br />zanemarljivim.</p> / <p>The potential use of sugar beet shreds for<br />copper ions removal from aqueous solution<br />in a fixed-bed column was investigated.<br />Experiments were performed using<br />Box-Behnken experimental design on three<br />levels and three variables: concentration of<br />the inlet solution (50-150 mgL^-1), adsorbent<br />dosage (8-12 g) and pH of the inlet solution<br />(4.0-5.0). The obtained breakthrough curves<br />were fitted with two common empirical<br />models, Bohart-Adams and dose-response.<br />Observing the asymmetric shape of the<br />breakthrough curves, the new mathematical<br />model was proposed. The new model<br />proposes the breakthrough curve composed<br />of two parts, sum of which gives the<br />asymmetrical S-shaped curve, accurately<br />matching experimental data. Regarding the<br />lowest average SSer (3.610^-3) and highest<br />average R² (0.9989), new model exhibited<br />the best fit comparing to the commonly used<br />models. RSM and ANN modelling were<br />employed for process variables evaluation and<br />optimization. The most influential parameter<br />exhibiting negative influence on target<br />response (critical time) was concentration of<br />the inlet solution, while the adsorbent dosage<br />exhibited positive influence. Optimization procedure revealed that the<br />highest critical time (341.4 min) was achieved<br />at following conditions: C0=50 mgL^-1,<br />ma=12 g and pH 4.53 by ANN, while<br />RSM considered pH as insignificant factor<br />and obtained 314.8 min as the highest<br />response. Discarded adsorbent, saturated<br />with copper ions, was then incinerated and<br />the obtained ash was used as a rubber filler.<br />Four rubber samples containing different<br />amounts of added ash were produced. The<br />vulcanization process was monitored and<br />mechanical properties was measured and<br />compared with the samples with no ash<br />added. The results revealed that addition of<br />ash has no significant effect on the rubber<br />mechanical properties. However, as the<br />ash content increases, the activation energy<br />of the vulcanization process increases too,<br />which can be considered as an improvement<br />in the cases of large-dimensioned rubber<br />products production. Finally, the leaching<br />of the copper from rubber products was<br />investigated. Results showed that very small<br />amount of copper, order of magnitude 0,001%,<br />were leached from the rubber into the water,<br />which can be considered as insignificant.</p>

D. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology / In the present era of water resources scarcity, efficient treatment of wastewater is a major prerequisite especially for growing economy. Numerous approaches have been studied for the development of cheaper and more effective adsorbents for removal of both organic and inorganic pollutants from wastewater. The present study seeks to harness the potential of biosorption and nanotechnology by producing more efficient, selective, mechanically stable and effective adsorbents for removal of organic and inorganic pollutants. The biosorbent-magnetic nanomaterial was synthesized by coating magnetite nanoparticles with sodium hydroxide treated pine cone by co-precipitation method. Magnetite coated pine bio-composite was then modified by cross-linking with hexamethylene diisocyanate and epichlorohydrin to the molecular recognition compound “cyclodextrin”. These novel biosorbent-magnetic nanoparticle materials were explored in overcoming the drawbacks of the biosorbent alone and selectively remove inorganic and organic pollutants from complex matrices. The synthesized materials were characterized by several analytical techniques including, Fourier Transformed Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM–EDX), Transmission Electron Microscopy (TEM), Brunauer, Emmett and Teller Isotherm (BET) surface area analysis, X-ray Photoelectron Spectroscopy (XPS), Vibrating Sample Magnetometer (VSM) and pH at point of zero charge (pHpzc). Sodium hydroxide treated pine cone and magnetite coated pine cone were applied for both chromium(VI) and arsenic(III) adsorption while the magnetite coated pine cone, magnetite coated pine cone crosslinked to cyclodextrin using both epichlorohydrin and hexamethylene diisocyanate were applied for 4-nitrophenol removal from aqueous solution. Batch adsorption studies were performed to optimize operating parameters such as solution pH, adsorbent dose, contact time, temperature and initial concentration. Pseudo first, pseudo second, intraparticle diffusion, pore and film diffusion kinetic models were determined to investigate the mechanism of adsorption process. Coefficient of correlation, r2, and variable error, methods were also applied in the determination of the best fit of the kinetic method. Structural characterization of magnetite coated pine cone and the magnetite coated pine crosslinked to cyclodextrin using 1,6-hexamethylene diisocyanate and epichlorohydrin were confirmed by characterization techniques applied. The adsorption of Cr(VI), As(III) and 4-nitrophenol was found to be dependent on the solution pH, adsorbent dose, initial concentration, temperature and ionic strength. Kinetic modelling revealed that the adsorption of Cr(VI), As(III) and 4-nitrophenol is controlled by pseudo second order kinetic model suggesting surface adsorption and intraparticle diffusion model. Intraparticle, pore and film diffusion models gave further insight into the controlling diffusion mechanism involved in the adsorption process for all pollutants investigated. Equilibrium studies indicated that the adsorption of all pollutants followed Langmuir isotherm indicating that adsorption sites are homogeneous in nature. The obtained thermodynamic parameters demonstrated that the adsorption of Cr(VI), As(III) and 4-nitrophenol were spontaneous, favourable and endothermic in nature. Anionic effect positively affected Cr(VI) and As(III) removal but had a negative effect on the 4-nitrophenol adsorption. Adsorption of 4-nitrophenol onto the nanocomposite adsorbents was attributed to multiple adsorbent-adsorbate interactions such as hydrogen bonding, hydrophobic attraction and guest host interaction. Magnetite coated pine better removed Cr(VI) and As(III) from aqueous solution than NaOH treated pine cone biomaterial while the magnetite coated pine crosslinked to cyclodextrin using 1,6-hexamethylene diisocyanate exhibited better adsorption performance for 4-nitrophenol removal than the nanocomposite crosslinked using epichlorohydrin and the magnetite coated pine cone.