Academic literature on the topic 'Biosorption of lead'

Problem statement: Major adsorbent materials used in heavy metal ion removal from polluted aqueous streams are expensive and difficult to regenerate. In this study, the possibility of using Zea mays tassel, as an alternative low cost biosorbent material to remediate heavy metal pollution was investigated. Lead (II) was used because of its wide application in industrial products and well documented toxicity. Approach: Tassel was obtained from mature Zea mays cultivar R52 hybrid plants. The tassel was milled to a powder and was used to adsorb lead(II) ions from simulated solutions in batch experiments. The desorption of lead(II) was carried out using nitric acid and sodium citrate solutions. The adsorbent was characterized by FTIR, EDX and ESCA before and after application of lead(II) solutions. Results: For samples with concentrations of 100 mg L-1 Pb(II), 94- 98% was adsorbed and 57-74 and 57-67% recoveries were achieved with 0.5-5 M nitric acid and 0.01- 0.2 M sodium citrate as the stripping solutions, respectively. EDX spectrum of pure tassel indicated that group 1 and 2 metals were the major exchangeable ions present on its surface. ESCA analysis picked up small amounts of lead(II) in the form of Pb(OH)+ and Pb(NH)+ ions on the surface of tassel adsorbent exposed to Pb2+ ions and none on pure tassel sample. Functional groups such as -H, -NH2, - C = O and -COOH which are polar and are legends which are capable of binding heavy metals were identified by FTIR. Conclusion: The potential of Zea mays tassel to adsorb and recover heavy metals from aqueous solution was successfully demonstrated with Pb(II) sample solutions. The results obtained thus far demonstrated the possibility of using tassel powder in the removal as well as recovery of metals from aqueous solutions.

Use of anaerobically digested sludge (ADS) in heavy metal removal, was researched. The raw and dewatered ADS samples collected from the effluent of anaerobic digesters and mechanical dewatering units of Ankara City Wastewater Treatment Plant were used. Sorption kinetic and equilibrium tests were conducted using raw ADS at initial pH of 2.0, 4.0 and without adjusting the initial pH. The highest Pb(II) removal capacity was observed as, 8.5 mmol (or 1760 mg) Pb(II) per g of biomass, when the initial pH was not controlled. When dewatered ADS was used Pb(II) removal capacity of ADS was found to drastically decrease to 2.5 mmol (or 518 mg) Pb(II) per g of biomass. Both biomass samples resulted in an increase in the solution pH from an initial value of 4 &ndash<br>5 to an equilibrium value of 7 &ndash<br>8. Large floc particles settling rapidly were formed after the ADS samples contacted with Pb(II) solution. The high Pb(II) removal capacities, and visual observations during the experiments indicated that precipitation is a dominant mechanism especially at low initial Pb(II) concentrations. FTIR studies showed that carboxyl groups present in the biomass surface of raw ADS were major functional groups in biosorption of Pb(II). The low capacity values attained at initial pH 2.0 indicated that there was a competition between Pb(II) species and hydrogen ions for carboxyl groups. Single and 3-stage fed-batch reactor systems were operated using raw ADS at different initial Pb(II) concentrations. The efficiency of reactor systems increased when 3-stage fed-batch configuration was used and an effluent Pb(II) concentration below 2 mg/L was reached from an initial value of about 200 mg/L.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2016-09-16T14:08:01Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE GARRETT FINAL - 18.05 - IMPRESSÃO.pdf: 2823940 bytes, checksum: 11d5e72c3c2f86d850cb1aeceab5cb36 (MD5)<br>Made available in DSpace on 2016-09-16T14:08:01Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE GARRETT FINAL - 18.05 - IMPRESSÃO.pdf: 2823940 bytes, checksum: 11d5e72c3c2f86d850cb1aeceab5cb36 (MD5) Previous issue date: 2016-02-15<br>CAPES<br>Os íons metálicos estão presentes em muitos processos industriais e, quando descartados ao meio ambiente, de forma inadequada, exigem atenção especial devido ao seu nível de periculosidade pode ocasionar efeitos prejudiciais aos seres vivos e consequentemente tornando-se um sério problema ambiental. A remoção desses contaminantes em efluentes líquidos tem sido tema de muitas pesquisas, mas o desafio consiste em encontrar um método seguro, eficaz e econômico capaz de tratar esses efluentes antes de serem descartados em qualquer corpo de água fluente. O processo de adsorção vem sendo utilizado como eficaz para a remoção de íons metálicos. Neste trabalho são apresentados estudos para avaliar a capacidade de biossorção de Cu2+ e Pb2+ aplicando cascas de camarão da espécie Litopenaeus vannamei e leveduras (Saccharomyces cerevisiae e Saccharomyces carlsbergensis) como biossorventes. As análises da fase aquosa monocomponentes e bicomponentes foram analisados pelo equipamento de absorção atômica. O ponto de carga zero (pHPCZ) determinado foi igual a 6,0 e o tempo mínimo de contato foi de 1 hora para a realização dos ensaios. Foram realizados testes de precipitação por 24 horas, verificando a concentração no início e no final do experimento, além disso, foi verificado a retenção do papel de filtro, valores entre 0,005% e 0,009%. Técnicas de caracterização como MEV com EDS, DSC/TG, TGA/DTA, DRX e infravermelho, foram importantes para o estudo e a confirmação dos parâmetros experimentais, como: Isotermas de adsorção e dessorção, o tamanho dos microporos fator determinante na acessibilidade das moléculas de adsorbato para a superfície interna de adsorção, verificação dos compostos químicos dos biossorventes e comportamento das reações endotérmicas ou exotérmicas. A técnica de planejamento experimental foi aplicada para otimização do processo de biossorção dos íons metálicos utilizando cada utilizando cada um dos biossorventes em estudo, onde as variáveis de entrada escolhidas foram velocidade de agitação, pH e temperatura. Os ensaios referentes ao estudo cinético e do equilíbrio do processo biossortivo com concentração de 20 mg.L-1 de íons metálicos foram realizados em batelada utilizando as melhores condições encontradas através dos planejamentos experimentais fatoriais. A variável temperatura apresentou efeito de maior significância na biossorção do Cu2+ para as duas espécies de levedura seguida da velocidade de agitação, enquanto para a casca de camarão o pH foi a variável mais significativa. O modelo de pseudo-segunda ordem apresentou melhor ajuste ao estudo cinético e equilíbrio da biossorção em todas as soluções metálicas pelas biomassas. Os estudos do equilíbrio da biossorção com concentração de 20 mg.L-1 dos íons metálicos Cu2+ e Pb2+ através da Saccharomyces carlsbergensis e casca de camarão se ajustaram melhor no modelo Langmuir-Freundlich com capacidade de adsorção máxima de 2,7 mg.g-1 e 3,75 mg.g-1 (Cobre – levedura e casca respectivamente) e 3,83 mg.g-1 e 4,29 mg.g-1 (Chumbo – levedura e casca respectivamente) em 30 minutos. E para os experimentos bicomponentes com capacidade adsortiva de 3,69 mg.g-1 e 3,97 mg.g-1 (Cobre e Chumbo – levedura e casca respectivamente) em 30 minutos. Os comportamentos termodinâmicos da adsorção para os íons metálicos foram avaliados de acordo com valores encontrados pela entalpia, entropia e energia livre de Gibbs. Valores positivos de ΔH, ΔS e valores negativos para ΔG, mostraram que a adsorção dos íons metálicos pelos biossorventes foi endotérmica, espontânea, favorável, e que a desordem do sistema aumentou durante o processo de adsorção.<br>The metal ions are present in many industrial processes, and when discarded to the environment, inappropriately, require special attention due to their level of dangerousness can cause harmful effects to living beings and consequently becoming a serious environmental problem. Removing these contaminants in wastewater has been the subject of much research, but the challenge is to find a safe, effective and economical method to treat the effluent before being discharged into any body of flowing water. The adsorption process is being used as effective for the removal of metal ions. This paper presents studies to evaluate the biosorption capacity of Cu2 + and Pb2 + applying shrimp shells of the species Litopenaeus vannamei and yeast (Saccharomyces cerevisiae and Saccharomyces carlsbergensis) as biosorbents. Analyses of single-component and two-component aqueous phase were analyzed by atomic absorption equipment. The point of zero charge (pHPCZ) determined was equal to 6.0 and the minimum contact time was 1 hour for the tests. precipitation for 24 hours Tests were conducted by checking the concentrations at the beginning and end of the experiment, moreover, was found to retain the filter paper, values between 0.005% and 0.009%. characterization techniques such as MEV with EDS, DSC / TG, TGA / DTA, XRD and infrared, were important for the study and confirmation of experimental parameters, such as isotherms of adsorption and desorption, the size of the micropores determining factor in accessibility of molecules adsorbate to the inner surface adsorption, verification of the chemical compounds of the biosorbents, and behavior of the endothermic or exothermic reactions. The experimental design optimization technique was applied to the biosorption process using each of the metal ions using each of biosorbents in a study where the input variables were chosen stirring speed, pH and temperature. The tests for the kinetic study and balance the biossortivo process with concentration of 20 mg L-1 of metal ions were conducted in batch mode using the best conditions found through the factorial experimental design. The variable temperature showed higher significant effect on biosorption of Cu2 + to the two yeast species followed by agitation speed, while for shrimp shells pH was the most significant variable. The pseudo-second-order model showed better fit to the kinetic study and balance of biosorption on all metal solutions by biomasses. Studies balance of biosorption with concentration of 20 mg L-1 of the metal ions Cu2 + and Pb2 + by Saccharomyces carlsbergensis and shrimp shell set best in the Langmuir-Freundlich model with maximum adsorption capacity of 2.7 mg.g- 1 and 3.75 mg.g-1 (Copper - yeast and shell respectively) and 3.83 mg g-1 and 4.29 mg.g-1 (Lead - yeast and shell respectively) for 30 minutes. And for the experiments bicomponent adsorptive capacity of 3.69 mg g-1 and 3.97 mg.g-1 (Copper and Lead - yeast and shell respectively) for 30 minutes. The thermodynamic behavior of adsorption for metal ions were evaluated according to values found by the enthalpy, entropy and Gibbs free energy. Positive values of ΔH, ΔS and negative values for ΔG, showed that the adsorption of metal ions by biosorbents was endothermic, spontaneous, favorable, and that the system disorder increased during the adsorption process.

Orientador: Devaney Ribeiro do Carmo<br>Resumo: A detecção, especiação e remoção de contaminantes orgânicos e inorgânicos é uma das maiores preocupações ambientais atualmente. Assim, a busca por tecnologias eficientes envolvendo materiais de baixo custo para a resolução de tal problema tem aumentado, e se tornou de extrema importância. Dentro deste contexto, o presente trabalho atuou na produção de um novo material nanoestruturado bioinorgânico híbrido com grandes potencialidades na área de nanotecnologia. O objetivo principal consistiu em modificar quimicamente a levedura Saccharomyces cerevisiae com silsesquioxanos cúbicos. Após devidas modificações, o material preparado (LevS) bem como seus precursores, foram caracterizados por técnicas espectroscópicas tais como infravermelho (FTIR) e microscopia eletrônica de varredura (MEV). O material hibrido formado (LevS) foi aplicado como biossorvente de chumbo (Pb) e níquel (Ni), obtendo-se uma capacidade máxima de sorção de 248 mg g-1 e 64,6 mg g-1, respectivamente, e porcentagem de sorção chegando a 100% para 500 ppm de Pb2+ em 250mLg-1 de razão líquido/sólido em pH 4, e 77,7% para 100 ppm de Ni2+ em 100 mLg-1 de razão líquido/sólido em pH 6. Adicionalmente com intuito de avaliar a toxidade neuronal dos metais em questão, foram efetuados testes de toxicidade em fatias de hipocampo de ratos que comprovaram que, uma vez submetidos à concentrações de 1 e 3 μM (0,2 e 0,6 ppm) Pb2+ e 10 e 30 μM (0,5 e 1,5 ppm) de Ni2+, as alterações neuronais causadas são irreversíveis. O material ... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The detection, speciation and organic and inorganic contaminants removal is one of the biggest environmental concerns today. Thus, the search for efficient technologies involving low-cost materials for solving such a problem has increased, and became extremely important. Within this context, the present work was focused in the production of a new nanostructured hybrid material bioinorganic with great potential in the area of nanotechnology. The main objective was chemically modify the yeast Saccharomyces cerevisiae with cubic silsesquioxane. After appropriate modifications, the prepared material (LevS) as well as its precursors was characterized by spectroscopic techniques such as infrared (FTIR), scanning electron microscopy (SEM), energy dispersive x-ray (EDS) and Diffuse Reflectance UV/Vis. The hybrid material formed (LevS) was applied as biosorbent of lead (Pb) and nickel (Ni), with a maximum capacity of sorption of 248 mg g-1 and 64.6 mg g-1, respectively, and percentage of reaching 100% sorption to 500 ppm of Pb2+ on 250 cm3 g-1 liquid/solid ratio and 4 pH, and 77.7% to 100 ppm of Ni2+ on 100 cm3 g-1 liquid/solid ratio at pH 6. In addition, in order to evaluate the neuronal toxicity of the metals in question, toxicity tests were performed on hippocampal slices of mice that proved that, once submitted to concentrations of 1 and 3 μM (0.2 and 0.6 ppm) Pb2+ and 10 and 30 μM (0.5 and 1.5 ppm) of Ni2+, neuronal changes caused are irreversible. The hybrid material was also te... (Complete abstract click electronic access below)<br>Doutor

Made available in DSpace on 2017-07-10T17:37:21Z (GMT). No. of bitstreams: 1 Fernanda_Rubio.pdf: 3072632 bytes, checksum: 474f6e13b902a88547c423612495ca4f (MD5) Previous issue date: 2012-03-30<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>Due to the intense pollution of the waters, is necessary the search for options which provide the remediation of the contaminated hydric resources, therefore the objective of this work was to evaluate the cake of crambe seeds (Crambe abyssinica Hochst) as a biosorbent in the removal of toxic heavy metals cadmium (Cd), lead (Pb) and chromium (Cr) in waters. The biomass was characterized by scanning electron microscopy (SEM), infrared spectroscopy (IR) and determination of the point of zero charge (pHpzc). The results demonstrate a favorable structure for the adsorption both by irregular morphology presented by SEM and by the functional groups indicated by IR. The result assigned by the pHpzc test of 5.5, the adsorption of cations the pH of the solution must be higher than the pHpzc. For the verification of the optimal conditions for the adsorption tests, the following factors were evaluated: variation effect of the biosorbent mass (200 to 1200 mg), pH of the solution (5.0, 6.0 and 7.0) and contact time (20 to 180 min). The results indicate that the best mass for the studies of the 3 metals (Cd, Pb and Cr) was of 400 mg. For the pH test, the solutions with pH 6.0 provided the best adsorption of Cd and Cr, while for the Pb the best pH was 7.0. In the kinetic study, the equilibrium was achieved in approximately 60 min for the Cd, 20 min for the Pb and 80 min for the Cr. After determinated the ideal conditions, tests were performed for the construction of the isotherms, ranging the concentration of the metals from 10 to 90 mg L-1. The bests adjusts for Cd, Pb and Cr followed the models of Freundlich and Dubinin-Radushkevich (D-R), describing a multilayer adsorption and with chemical nature, still confirmed by the pseudo second-order test. The estimated value of the maximum capacity of adsorption by biosorbent mass (qm) for Cd was 19.342 mg g-1, for Cr 6.807 mg g-1 and for Pb was not possible to determinate this parameter due to the non-linearity presented. The influence of the temperature was studied for the determination of the thermodynamic parameters, which was performed using optimal conditions ranging temperature from 25 to 65 ºC. The positive values of ΔH e ΔS indicate a endothermic process and a randomness system, respectively. Only for the Pb was found negative ΔG, referring to a spontaneous adsorption. The percentage of removal of the ions was of: Pb 97%, Cd 76% e Cr 45%. In the desorption, only the Cd was able to be successfully recovered. Using the same conditions applied for the biosorbent crambe, comparative tests of adsorption and desorption were performed using commercial activated coal. By the obtained results and knowing that the cake of crambe seeds are a byproduct available in high scale and which did not undergone any previous treatment, was verified high applicability of this material as biosorbent in the treatment of contaminated waters with Cd, Pb and Cr, presenting itself as a viable alternative for the decrease of the environmental impacts, because it s a byproduct and it present itself as a natural and sustainable material<br>Devido a intensa poluição das águas, a busca por alternativas que propiciem a remediação dos recursos hidrícos contaminados faz-se necessária, por isso o objetivo deste trabalho foi avaliar a aplicabilidade do uso da torta de sementes de Crambe abyssinica Hochst (crambe) como biossorvente na remoção dos metais pesados tóxicos cádmio (Cd), chumbo (Pb) e cromo (Cr) presentes em águas. A biomassa de crambe foi caracterizada por microscopia eletrônica de varredura (MEV), espectroscopia de infravermelho (IV) e determinação do ponto de carga zero (pHPCZ). Os resultados demonstraram estrutura favorável para adsorção tanto pela morfologia irregular apresentada pelo MEV, quanto pelos grupos funcionais indicados pelo IV. Na determinação do pHPCZ o resultado obtido foi de 5,5, indicando que para a adsorção de cátions é favorável em soluções com pH acima do pHPCZ. Para verificação das condições ótimas para os estudos de adsorção, foram avaliados os seguintes fatores: o efeito da variação da massa do biossorvente (200 a 1200 mg), pH da solução (5,0; 6,0 e 7,0) e tempo de contato (20 a 180 min). Os resultados indicaram que a melhor massa para os estudos dos três metais (Cd, Pb e Cr) foi de 400 mg. Para o estudo de pH, as soluções com pH 6,0 propiciaram a melhor adsorção de Cd e Cr, enquanto que para o Pb o melhor pH foi 7,0. No estudo cinético, o equilíbrio do sistema foi atingido em aproximadamente 60 min para o Cd, 20 min para Pb e 80 min para Cr. Determinadas as condições ideais, estudos foram realizados para a construção das isotermas, variando-se a concentração dos metais de 10 a 90 mg L-1. Os melhores ajustes tanto para Cd, Pb e Cr seguiram os modelos de Freundlich e Dubinin-Radushkevich (D-R), descrevendo uma adsorção em multicamadas e de natureza química, confirmada ainda pelo modelo de pseudossegunda ordem. O valor estimado da quantidade máxima (qm) de Cd adsorvida por massa do biossorvente foi de 19,342 mg g-1, para o Cr 6,807 mg g-1 e para o Pb não foi possível determinar este parâmetro devido a não linearidade apresentada pelo modelo. A influência da temperatura foi estudada para determinação dos parâmetros termodinâmicos, para isso, utilizando as condições ótimas variou-se a temperatura em 25 a 65 ºC. Os valores positivos de ΔH e ΔS indicaram processo endotérmico e aleatoriedade do sistema, respectivamente. Somente o metal Pb obteve ΔG negativo, referindo-se a uma adsorção espontânea. A porcentagem de remoção dos íons foi de: Pb 97%, Cd 76% e Cr 45%. Na dessorção, apenas o metal Cd pôde ser satisfatoriamente recuperado. Utilizando as mesmas condições empregadas para o bissorvente crambe, estudos comparativos de adsorção e dessorção foram efetuados utilizando carvão ativado comercial. Diante dos resultados e sabendo que a torta das sementes de crambe é um coproduto disponível em larga escala e que não sofreu nenhum tratamento prévio, verificou-se a alta aplicabilidade desse material como biossorvente no tratamento de águas contaminadas com Cd, Pb e Cr, sendo uma alternativa viável para diminuição dos impactos ambientais, por se tratar de um coproduto e desta forma constitui-se um material natural e sustentável

Orientador: Crispin Humberto Garcia Cruz<br>Banca: Eleni Gomes<br>Banca: Roberto Alves de Oliveira<br>Resumo: Os polímeros microbianos extracelulares (exo-biopolímeros) são moléculas que apresentam um grande potencial de aplicação nas indústrias de alimentos, farmacêuticas, petrolíferas, de cosméticos, têxteis, de papéis, tintas, produtos agrícolas entre outras. Como biorremediadores, podem ser utilizados na remoção de metais pesados em ambientes aquáticos poluídos, atuando como agentes de biossorção por meio da acumulação de nutrientes a partir do meio ambiente. O objetivo do trabalho foi a produção de exobiopolímeros a partir de três Ascomicetos endofíticos (Colletotrichum sp., Guignardia sp. e Phomopsis sp.). Foi selecionado o fungo que apresentou a maior produção desse material biológico. Tanto esse exo-biopolímero quanto a biomassa foram avaliados quanto aos seus potenciais de biossorção dos íons metálicos chumbo (Pb+2) e cádmio (Cd+2). Para a obtenção do meio de cultivo utilizado para a produção de exo-biopolímeros, foram testados o meio mínimo de sais de Vogel modificado com diferentes fontes de nitrogênio definidas e glicose como única fonte de carbono. Em seguida, foi realizado um planejamento fatorial 3(3-0) com 27 experimentos em duplicata, onde as variáveis independentes foram o tempo, temperatura de cultivo e a concentração inicial de glicose. O fungo Colletotrichum sp. apresentou a maior produção de exo-biopolímero (5,71 gL-1) utilizando a uréia como fonte de nitrogênio, em cultivo a 28 ºC, 150 rpm e glicose 6 % (p/v) em 192 horas de cultivo. A execução do planejamento fatorial demonstrou que a produção de biomassa seca foi favorecida por faixas de temperatura e concentração inicial de glicose entre 24 e 32 ºC e 35 e 75 gL-1, respectivamente. A produção de exo-biopolímero foi favorecida por faixas de temperatura e concentração... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The microbial extracellular polymer (exo-biopolymers) are molecules that have a great potential for application in the industries of food, pharmaceutical, oil, cosmetics, textiles, paper, paints, agricultural products and others. As bioremediation, can be used in the removal of heavy metals in polluted aquatic environments, acting as agents of bioremediation through the accumulation of nutrients from the environment. Objective of this study was to produce exo-biopolymer from three endophytic Ascomycota (Colletotrichum sp., Guignardia sp. and Phomopsis sp.). Then, was selected the fungus that showed the highest production of exobiopolymer. Both the exo-biopolymer and biomass were assessed for their potential of biosorption of metallic ions lead (Pb+2) and cadmium (Cd+2). To obtain the culture medium used for the production of exo-biopolymers, was tested a minimal medium salts of Vogel modified with different nitrogen sources and glucose defined as the only carbon source. Next, was performed a factorial design 3(3-0) with 27 experiments in duplicate, where the independent variables were the time and temperature of cultivation and the initial concentration of glucose. Colletotrichum sp. had the highest production of exo-biopolymer (5.71 gL-1) using urea as the nitrogen source in cultivation at 28 ºC, 150 rpm, and glucose 6% (w/v) in 192 hours of culture. The implementation of the factorial design showed that the dry biomass production was enhanced by a range of temperatures and initial concentration of glucose between 24 and 32 ºC and 35 and 75 gL-1, respectively. The production of exobiopolymer was favored by a range of temperatures and initial concentration of glucose between 24 and 36 ºC and 35 and 70 gL-1, respectively. In the experiment, the fungus Colletotrichum sp. produced 6.11 gL-1 of... (Complete abstract click electronic access below)<br>Mestre

Made available in DSpace on 2014-06-11T19:27:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-23Bitstream added on 2014-06-13T20:35:42Z : No. of bitstreams: 1 silva_lj_me_sjrp.pdf: 1135399 bytes, checksum: 5c78b7f4373a9244db399ef5e02efdad (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Os polímeros microbianos extracelulares (exo-biopolímeros) são moléculas que apresentam um grande potencial de aplicação nas indústrias de alimentos, farmacêuticas, petrolíferas, de cosméticos, têxteis, de papéis, tintas, produtos agrícolas entre outras. Como biorremediadores, podem ser utilizados na remoção de metais pesados em ambientes aquáticos poluídos, atuando como agentes de biossorção por meio da acumulação de nutrientes a partir do meio ambiente. O objetivo do trabalho foi a produção de exobiopolímeros a partir de três Ascomicetos endofíticos (Colletotrichum sp., Guignardia sp. e Phomopsis sp.). Foi selecionado o fungo que apresentou a maior produção desse material biológico. Tanto esse exo-biopolímero quanto a biomassa foram avaliados quanto aos seus potenciais de biossorção dos íons metálicos chumbo (Pb+2) e cádmio (Cd+2). Para a obtenção do meio de cultivo utilizado para a produção de exo-biopolímeros, foram testados o meio mínimo de sais de Vogel modificado com diferentes fontes de nitrogênio definidas e glicose como única fonte de carbono. Em seguida, foi realizado um planejamento fatorial 3(3-0) com 27 experimentos em duplicata, onde as variáveis independentes foram o tempo, temperatura de cultivo e a concentração inicial de glicose. O fungo Colletotrichum sp. apresentou a maior produção de exo-biopolímero (5,71 gL-1) utilizando a uréia como fonte de nitrogênio, em cultivo a 28 ºC, 150 rpm e glicose 6 % (p/v) em 192 horas de cultivo. A execução do planejamento fatorial demonstrou que a produção de biomassa seca foi favorecida por faixas de temperatura e concentração inicial de glicose entre 24 e 32 ºC e 35 e 75 gL-1, respectivamente. A produção de exo-biopolímero foi favorecida por faixas de temperatura e concentração...<br>The microbial extracellular polymer (exo-biopolymers) are molecules that have a great potential for application in the industries of food, pharmaceutical, oil, cosmetics, textiles, paper, paints, agricultural products and others. As bioremediation, can be used in the removal of heavy metals in polluted aquatic environments, acting as agents of bioremediation through the accumulation of nutrients from the environment. Objective of this study was to produce exo-biopolymer from three endophytic Ascomycota (Colletotrichum sp., Guignardia sp. and Phomopsis sp.). Then, was selected the fungus that showed the highest production of exobiopolymer. Both the exo-biopolymer and biomass were assessed for their potential of biosorption of metallic ions lead (Pb+2) and cadmium (Cd+2). To obtain the culture medium used for the production of exo-biopolymers, was tested a minimal medium salts of Vogel modified with different nitrogen sources and glucose defined as the only carbon source. Next, was performed a factorial design 3(3-0) with 27 experiments in duplicate, where the independent variables were the time and temperature of cultivation and the initial concentration of glucose. Colletotrichum sp. had the highest production of exo-biopolymer (5.71 gL-1) using urea as the nitrogen source in cultivation at 28 ºC, 150 rpm, and glucose 6% (w/v) in 192 hours of culture. The implementation of the factorial design showed that the dry biomass production was enhanced by a range of temperatures and initial concentration of glucose between 24 and 32 ºC and 35 and 75 gL-1, respectively. The production of exobiopolymer was favored by a range of temperatures and initial concentration of glucose between 24 and 36 ºC and 35 and 70 gL-1, respectively. In the experiment, the fungus Colletotrichum sp. produced 6.11 gL-1 of... (Complete abstract click electronic access below)

As algas marrons do gênero Sargassum têm sido estudadas como potenciais candidatas ao processo de biossorção, objetivando tratar efluentes contaminados com metais pesados. A estrutura celular deste gênero de alga apresenta moléculas carregadas, como o ácido algínico, capazes de atrair e captar cátions metálicos. A proposta deste trabalho foi avaliar a capacidade de captação dos íons cobre e chumbo pela alga marinha Sargassum através de ensaios cinéticos e de acumulação com modelagem cinética e das isotermas para sistemas monocomponente e binário. O equilíbrio de captação foi atingido em 30 minutos e a cinética do processo foi representada por um modelo de segunda ordem. No sistema monocomponente, onde as soluções continham inicialmente 10 mg/L de cada íon metálico a captação no equilíbrio foi 0,06 mmol/g de íons Cu (II) e 0,02 mmol/g de íons Pb (II). Para as soluções contendo 50 mg/L a captação no equilíbrio foi 0,37 mmol/g de íons Cu (II) e 0,11 mmol/g de íons Pb (II), individualmente. A capacidade de biossorção foi reduzida no sistema binário mostrando que a presença de um segundo metal afeta a captação dos íons. Os valores de qmax para íons Pb (II) no sistema binário foi 0,6 mmol/g contra 1,2 mmol/g no sistema monocomponente; para íons Cu (II) a captação foi 0,7 mmol/g contra 1,8 mmol/g. Na biossorção binária a captação de íons Pb (II) manteve o percentual de remoção mesmo em soluções com elevadas concentrações de íons Cu (II); o contrário não foi observado para o Pb(II), indicando que íons Pb (II) interferem mais na captação de íons Cu (II). Para o estudo do equilíbrio monocomponente foram utilizados os modelos de Langmuir e Freundlich; para o sistema binário, o Langmuir competitivo, Langmuir modificado, Langmuir-Freundlich e Freundlich estendido. Os modelos não foram conclusivos, porém elucidaram aspectos relacionados ao mecanismo, apresentando alto grau de dispersão entre a captação experimental e as teóricas.<br>Brown seaweeds from the genus Sargassum are widely studied for use as potential candidates for biosorption purposes, particularly in the treatment of heavy-metals contaminated effluents. The cellular structure of this seaweed presents charged molecules, such as alginic acid, able to attract and recover metal cation ions. The objective of this work was to study the uptake capacity of copper and lead by the seaweed Sargassum, through kinetic and isotherm studies with the help of kinetic and isotherm models for monocomponent and binary solutions. Equilibrium uptake was reached in 30 minutes and the kinetic behavior of the process followed a second-order model. In monocomponent systems, at 10 mg/L metal concentration, equilibrium uptake indicated a recovery of 0.06 mmol Cu(II)/g biomass and 0.02mmol/g Pb(II)/g biomass. When a 50 mg/L solution was used, the individual uptake was equal to 0.37 mmol Cu(II)/g biomass and 0.11 mmol Pb(II)/g biomass. Uptake was markedly reduced by the presence of the second metal in solution indicating the interference in biosorption in a multi-ion solution. Values of qmax for Pb(II) in the binary system was equal to 0.6 mmol/g biomass, against 1.2 mmol/g biomass in the monocomponent situation; for Cu(II) the uptake was equal to 0.7 mmol/g biomass against 1.8 mmol/g biomass, in the monocomponent solution. In the binary solution, Pb(II) uptake kept the same percent removal, even in the presence of high concentrations of Cu(II); an opposite behavior was observed for Cu(II), indicating that Pb(II) interfere in the uptake of Cu(II) more than the opposite situation. In the monocomponent equilibrium models such as Langmuir and Freundlich were used to fit experimental data. In binary systems, Competitive Langmuir, Modified Langmuir, Langmuir-Freundlich and Extended Freundlich Extented were used. All the models were not conclusive to fit experimental results, however they contributed for a better understanding of the mechanism involved in biosorption, because a high level of dispersion between actual biosorption and theoretical prediction was observed.

This study will introduce anaerobic granules as a novel type of biosorbent for the removal of lead, copper, cadmium, and nickel from aqueous solutions. The work investigated the equilibrium, batch dynamics and continuous column operation for the biosorption process. Binding capacity experiments using viable biomass revealed a higher value than those for nonviable biomass. Binding capacity experiments using non-viable biomass treated with Ca revealed a high value of metals uptake. The solution initial value affected metal sorption. Time dependency experiments for the metal ions uptake showed that adsorption equilibrium was reached almost 30 minutes after metal addition. It was found that the q max for Pb 2+ , Cu 2+ , Cd 2+ and Ni 2+ , were 2.46, 1.74, 1.06 and 0.88 meq/g respectively. The data pertaining to the sorption dependence upon metal ion concentration fitted the Langmiur isotherm model. The kinetics of sorption of Pb 2+ , Cu 2+ , Cd 2+ and Ni 2+ were modelled using a pseudo-second order rate equation. Column adsorption studies were performed for Pb 2+ , Cu 2+ , Cd 2+ , and Ni 2+ . The removal of Pb 2+ , Cu 2+ , Cd 2+ , and Ni 2+ ions from the bed was accompanied by the elution of Ca 2+ ions from the packed-bed. Ion exchange was identified to be the dominant mechanism for the biosorption of nickel by the anaerobic biomass. For copper and cadmium 77% and 82% of the total amount adsorbed was attributed to ion exchange respectively. 18% and 15% of the total amount adsorbed of copper and cadmium was attributed to the extent of a complexation process competing with the ion exchange one respectively. For the case of Pb ions it was found out that ion exchange was attributed to be almost 50% of the total uptake mechanism. 30% of the total uptake mechanism was attributed to precipitation mechanism. The remaining 20% was attributed to a complexation process competing with the ion exchange and precipitation. The affinity order of anaerobic biomass for the four metals under study has been established as: Pb > Cu > Ni > Cd. The selectivity of the biomass for Pb over the other three metals was well exhibited by the results obtained using the flow-through column