Utilização de novos agentes ligantes obtidos a partir de biomassas para determinação de íons metálicos por meio de técnica de difusão em filmes finos por gradiente de concentração
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2017-04-12
Autores
Yabuki, Lauren Nozomi Marques [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A técnica de difusão em filmes finos por gradiente de concentração (DGT) tem se consolidado como uma excelente ferramenta analítica capaz de fornecer concentrações lábeis por tempo, pré-concentração dos analitos e amostragem in situ, porém a aplicação desta técnica em águas de drenagem ácida de mina (DAM) é complicada devido à redução da adsorção do amostrador tradicional (resina ligante Chelex-100) para metais em baixo pH. Este estudo, avalia a utilização da técnica DGT para determinação das concentrações lábeis de Al, Cd, Cu, Mn, Ni, Pb U e Zn em águas de DAM, empregando novos agentes ligantes preparados a partir de biomassas (cascas de banana, borra de café e sementes de moringa) impregnadas em agarose. As medições DGT foram realizadas em soluções padrão em laboratório e in situ. Resultados laboratoriais mostram que os agentes ligantes podem ser empregados em águas com pH baixo (pH 3,5) para os íons Cd, Cu, Ni, Pb e Zn. Já os íons Al, Mn e U não apresentaram linearidade nas curvas de imersão para nenhuma biomassa pesquisada. Para a análise de amostras in situ de DAM, houve baixas recuperações dos íons Cd, Cu, Ni e principalmente para Zn com 5,7% da fração solúvel com o gel de agarose-moringa, podendo indicar a baixa eficiência dos agentes ligantes ou algum efeito matriz inerente durante a determinação por ICP-OES. Por outro lado, houve recuperações satisfatórias para a imersão em amostras do Rio Corumbataí e do Rio Piracicaba, ressaltando o emprego destes agentes ligantes pesquisados em matrizes aquáticas diferentes das matrizes de DAM. Este estudo mostra que o uso da técnica DGT pode ser estendido para águas com pH baixo (desde que sejam avaliados as limitações e condições de contorno avaliadas neste estudo) podendo ser uma ferramenta útil para o monitoramento em tempo integrado de concentrações lábeis em diferentes sistemas aquáticos.
The diffusive gradients in thin films (DGT) technique has consolidated as an excellent analytical tool capable of providing labile concentrations by time, analytical preconcentration and in situ sampling, but the application of this technique in acid mine drainage waters (AMD) is limited by the reduction of adsorption of the traditional binding layer (Chelex-100 chelating resin) to metals at low pH. This study proposes the use of the DGT technique to determine the concentrations of Al, Cd, Cu, Mn, Ni, Pb U and Zn in AMD using new binding agents prepared from biomass (Musa cavendishi banana peel, spent coffee grounds and shelled Moringa Oleifera seeds) impregnated with agarose. DGT measurements were performed in laboratory standard solutions and in situ. Laboratory results showed that the binding agents can be used in waters with low pH (pH 3.5) for Cd, Cu, Ni, Pb and Zn. Al, Mn and U ions did not present linearity in the deployment curves for any biomass studied. For the analysis of in situ AMD samples, there were low recoveries of the Cd, Cu, Ni, and mainly Zn ions with 5.7% of the soluble fraction with the agarose-moringa gel, indicating the low efficiency of the binding agents at low values pH or some inherent matrix effect during determination by ICP-OES. On the other hand, there were satisfactory recoveries for deployment in samples from the Corumbataí River and the Piracicaba River, highlighting the use of these binding layers in aquatic matrices other than AMD matrices. This study shows that the use of the DGT technique can be extended to waters with low pH (provided that the limitations and contour conditions evaluated in this study are evaluated) and can be a useful tool for the integrated time monitoring of labile concentrations in different aquatic systems.
The diffusive gradients in thin films (DGT) technique has consolidated as an excellent analytical tool capable of providing labile concentrations by time, analytical preconcentration and in situ sampling, but the application of this technique in acid mine drainage waters (AMD) is limited by the reduction of adsorption of the traditional binding layer (Chelex-100 chelating resin) to metals at low pH. This study proposes the use of the DGT technique to determine the concentrations of Al, Cd, Cu, Mn, Ni, Pb U and Zn in AMD using new binding agents prepared from biomass (Musa cavendishi banana peel, spent coffee grounds and shelled Moringa Oleifera seeds) impregnated with agarose. DGT measurements were performed in laboratory standard solutions and in situ. Laboratory results showed that the binding agents can be used in waters with low pH (pH 3.5) for Cd, Cu, Ni, Pb and Zn. Al, Mn and U ions did not present linearity in the deployment curves for any biomass studied. For the analysis of in situ AMD samples, there were low recoveries of the Cd, Cu, Ni, and mainly Zn ions with 5.7% of the soluble fraction with the agarose-moringa gel, indicating the low efficiency of the binding agents at low values pH or some inherent matrix effect during determination by ICP-OES. On the other hand, there were satisfactory recoveries for deployment in samples from the Corumbataí River and the Piracicaba River, highlighting the use of these binding layers in aquatic matrices other than AMD matrices. This study shows that the use of the DGT technique can be extended to waters with low pH (provided that the limitations and contour conditions evaluated in this study are evaluated) and can be a useful tool for the integrated time monitoring of labile concentrations in different aquatic systems.
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Palavras-chave
Banana, Café, Moringa, Metais traço, DGT