Aplicações de Vermiculitas no Tratamento de Efluentes Contendo Metais Pesados

Abstract

One of the great environmental impacts promoted by the growth of industrial activities is the contamination by metallic ions. In Brazil, only 28% of the industrial residues receive adequate treatment, and the other 72% are disposed of in dumps or water bodies without any kind of treatment. The current environmental policy encourages the emergence of alternative methods of treatment of these effluents, such as electrodialysis, reverse osmosis, ultra-filtration and adsorption in natural materials that promote the selective and reversible retention of metal cations. The vermiculite, a mineral of the mica group, has as characteristics the high porosity, besides an excellent capacity of ionic exchange, which makes it suitable for application in the treatment of effluents containing metallic ions. In this work the objective is to study the efficiency of the use of vermiculite in the adsorption of metallic ions (copper). For this, vermiculite samples from the states of Paraíba and Goiás were used. The tests were performed for purely expanded samples and also for expanded samples activated with 1M NaCl. First, adsorption kinetics assays were performed, where 97% adsorption efficiency was achieved after 2 hours of contact between the activated vermiculite and the copper solution (10 g of activated vermiculite from Paraíba and 11 of solution containing 200 ppm of copper ions). In the adsorption assays, the results were also satisfactory, presenting efficiencies close to 100% (99.89%) for 19 g of activated vermiculite from Paraiba adsorbing 100 mL of solution containing 100 ppm of copper ions. The data obtained were also compared with literature data. In addition, studies using adsorption isotherms from the literature were performed and proved that the material behaves as an excellent adsorbent.