Estudo comparativo da capacidade de adsorção de metais pesados por caulins modificados da província pegmatítica da Borborema

Abstract

Nowadays the major environmental problems are directly related to soil contamination and water resources by toxic heavy metals. Mitigation techniques using smectite clays, modified, as raw material for the development of new materials with applications in sorptive processes. In this context, the modified kaolinite has been used as an alternative in the adsorption processes of heavy metals. Considering that, this work aims to characterize and to evaluate in a comparative way the sorptive efficiency of heavy metals by kaolins coming from the Pegmatitic Province of Borborema. Therefore, the kaolin, tailing and concentrate were collected in the Equador/RN and Junco do Seridó/PB municipalities. The kaolin tailings were submitted to the beneficiation tests. Concentrated samples and benefited kaolin were submitted to structural modification by the acetic solution 30% addition, mass percentage. The cation exchange capacity of the concentrated kaolin was evaluated by the methylene blue method. The modified samples were submitted to adsorption tests of heavy metals, Cr (III) and Pb (II). The samples were then characterized by diffractometry, X-ray fluorescence, thermogravimetric and differential thermal analysis, and by scanning electron microscopy. The treatment of tailings proved to be efficient, with results corroborated by X-ray diffraction, as well as the structural kaolins modification proved by the increase of approximately 90% of the kaolinite basal space plane (001). All the samples of kaolin, modified and beneficiated, showed efficiency in the heavy metals adsorption, Cr (III) and Pb (II), especially the sample of tailing benefiting from Rio Grande do Norte, which recorded the best result.