Efeito da adição de nanopartículas na biolixiviação da calcopirita ('CU''FE''S IND.2') por Acidithiobacillus ferrooxidans LR
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Data
2011-06-02
Autores
Silva, Daniel Rodrigues da [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A biolixiviação (lixiviação bacteriana) é uma alternativa para a extração de metais presentes em sulfetos minerais empregando microorganismos. Dentre as principais vantagens da biohidrometalurgia em relação aos métodos convencionais podem ser destacadas a não-emissão de SO2 para a atmosfera, pequeno gasto com insumos, pois são produzidos pelos próprios microorganismos, baixa demanda energética e o tratamento de minérios contendo metais em baixo teor. Uma das espécies envolvidas na biolixiviação de sulfetos minerais mais estudadas é Acidithiobacillus ferrooxidans. Essa bactéria é gram negativa, aeróbia, acidófila, mesófila e obtém energia através da oxidação de íons Fe2+ e compostos reduzidos de enxofre. A calcopirita é a principal fonte de cobre presente na crosta terrestre. Uma das principais propriedades desse sulfeto é a sua alta refratariedade ao ataque químico e bacteriano, conseqüência da sua elevada energia de rede cristalina. Além disso, a formação de uma camada protetora, constituída basicamente por polissulfetos, sobre a sua superfície diminui a dissolução desse minério. Por isso, diversos grupos de pesquisa buscam alternativas para a resolução desses problemas visando elevar as extrações de cobre a partir desse sulfeto. Com esse objetivo, o presente trabalho estudou o efeito da adição de nanopartículas, polares e apolares, na biolixiviação da calcopirita por A. ferrooxidans LR. O único estudo relacionado à lixiviação envolvendo nanopartículas demonstrou que a adição de nanosílica elevou as taxas de dissolução da calcopirita mediante utilização de agentes oxidantes, meio reacional ácido e temperatura moderada. Para avaliar o efeito da adição de nanopartículas no crescimento bacteriano, foi monitorada a concentração de íons Fe2+ presentes em sistemas contendo A. ferrooxidans...
Bioleaching is an alternative for metal extraction from mineral sulfides using microorganisms. The main advantages of the biotechnological processes in comparison with usual methods of metal extraction are the non-emission of SO2 to atmosphere, lower inputs cost, as they are produced by the microorganisms themselves, lesser energy requirements and treatment of low-grade ores. One of the most studied microbes involved in the bioleaching of mineral sulfides is Acidithiobacillus ferrooxidans. This bacterium is Gram-negative, aerobic, acidophilic, mesophilic and oxidizes Fe2+ ions and reduced forms of sulfur to obtain energy. Chalcopyrite is the main copper source present in the world. One of its main properties is the high resistance to the chemical and bacterial attacks, result of its great crystal lattice energy. Also, the formation of a protective layer, mainly constituted by polysulfides, over its surface reduces the dissolution of that ore. For those reasons, several research groups throughout the world are investigating alternatives to solve these problems and promote the higher copper extraction from this sulfide. This work studied the effect of adding nanoparticles, polar and non-polar, in the bioleaching of chalcopyrite by A. ferrooxidans LR. The only study related to leaching involving nanoparticles, published in 2005, demonstrated that the addition of nano-sized silica raised the dissolution rates of chalcopyrite when using oxidizing agents, acidic medium and moderate temperature. To evaluate the effect of adding nanoparticles in bacteria growth, it was monitorated the Fe2+ ions concentration present in flasks that contained A. ferrooxidans LR and different concentrations of nanoparticles. Thus, it was observed that high amounts of nanoparticles (> 2.5% m/v) affected the bacteria growth. Shake flasks... (Complete abstract click electronic access below)
Bioleaching is an alternative for metal extraction from mineral sulfides using microorganisms. The main advantages of the biotechnological processes in comparison with usual methods of metal extraction are the non-emission of SO2 to atmosphere, lower inputs cost, as they are produced by the microorganisms themselves, lesser energy requirements and treatment of low-grade ores. One of the most studied microbes involved in the bioleaching of mineral sulfides is Acidithiobacillus ferrooxidans. This bacterium is Gram-negative, aerobic, acidophilic, mesophilic and oxidizes Fe2+ ions and reduced forms of sulfur to obtain energy. Chalcopyrite is the main copper source present in the world. One of its main properties is the high resistance to the chemical and bacterial attacks, result of its great crystal lattice energy. Also, the formation of a protective layer, mainly constituted by polysulfides, over its surface reduces the dissolution of that ore. For those reasons, several research groups throughout the world are investigating alternatives to solve these problems and promote the higher copper extraction from this sulfide. This work studied the effect of adding nanoparticles, polar and non-polar, in the bioleaching of chalcopyrite by A. ferrooxidans LR. The only study related to leaching involving nanoparticles, published in 2005, demonstrated that the addition of nano-sized silica raised the dissolution rates of chalcopyrite when using oxidizing agents, acidic medium and moderate temperature. To evaluate the effect of adding nanoparticles in bacteria growth, it was monitorated the Fe2+ ions concentration present in flasks that contained A. ferrooxidans LR and different concentrations of nanoparticles. Thus, it was observed that high amounts of nanoparticles (> 2.5% m/v) affected the bacteria growth. Shake flasks... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Bioquímica, Nanopartículas, Acidithiobacillus ferrooxidans, Biochemistry, Nanoparticles
Como citar
SILVA, Daniel Rodrigues da. Efeito da adição de nanopartículas na biolixiviação da calcopirita ('CU''FE''S IND.2') por Acidithiobacillus ferrooxidans LR. 2011. 81 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Química, 2011.