APLICAÇÃO DE ARGILA ORGANOFÍLICA PARA A ADSORÇÃO DE METAIS PESADOS PRESENTES EM RESÍDUOS DE CURTUME

Abstract

The present work claimed to evaluate the use of organophilic clay in the removal of heavy metals Cr (VI) and Fe (II) present in aqueous solutions. Part of the clay in nature sample was chemically treated with CTAB, giving rise to the organophilic clay. Through the analysis of the infrared spectrum of clay in nature and organophilic clay, it was possible to identify the groups of functions CH2 and CH3, which show the replacement of inorganic cations present in interlamellar clay spaces with CTAB cations. Through the pH effect test, it was found that pH 2 is the most efficient for the adsorption of Cr (VI) since at this pH the surface of the adsorbent is highly protonated, affecting the electrostatic interaction with this anion. The pH 5 showed the most efficient for Fe (II), since this cause undergoes repulsion of the surface at low pH, and this repulsion decreases with the increase in pH. The kinetic model that best fitted both tested metal ions was the pseudo-second order. The Langmuir and Freundlich isothermal models were submitted to the evaluation of experimental results, and Freundlich presented the best fit for both metals. In the competitive adsorption study at pH 2 and 4, Fe (II) obtained 100% adsorption at both pH’s while Cr (VI) obtained removal rates of 62.6 and 64,7% at pH 2 and 4 respectively.