Imobilização de lantânio por coloides sintéticos de ferro e alumínio

• Autor(a) principal: Pietralonga, Aloncio Gottardo
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5508
• topic: Lantânio; Coloides Sintéticos; Elementos terra raras; Lanthanum; Synthetic colloids; Rare earth elements; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

Lanthanum is one of the 17 chemical elements known as rare earths. The increasing use of these metals by industries and impacts of mining have contributed to their mobility in the environment, creating possible environmental hazards and health effects. In this study, we evaluated the La removal from aqueous solution through the synthesis of iron and aluminum colloids via precipitation and the retention of this contaminant in the solid phases formed. Solutions of ferrous sulfate, aluminum sulfate and lanthanum sulfate were mixed in different proportions, in polyethylene containers, so as to obtain ten Fe: Al: La molar ratios(500:125:0, 500:125:1, 500: 125:5, 500:125:25, 500:125:125, 500:250:0, 500:250:1, 500:250:5, 500:250:25 and 500:250:125). The experimental period was 90 days. Supernatant aliquots were collected to determine lanthanum concentration weekly. The precipitated material was characterized by color determination by the Munsell system, X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS). Potential remobilization of lanthanum in the solid phases formed was evaluated by comparing the amounts extractable by acetic acid 0.11 mol L-1 with the total contents, both determined by ICP OES. High efficiencies in lanthanum removal from aqueous phase were obtained. The precipitate colors tended to redden with the increments in lanthanum amount. The XRD detected the formation of Al-goethite in most treatments and other phases such as Al-lepidocrocite and Al-magnetite, in specific cases. Microanalysis revealed the lanthanum association to iron and aluminum colloids in the solid phase and the occurrence of segregation where the element was more abundant. The extractions with acetic acid showed high potential remobilization of lanthanum to most treatments. The method is suitable for removing the contaminant from water, but further studies are necessary to optimize retention in the solid phase.