Characterization and Modification of a Clay Mineral Used in Adsorption Tests

Abstract

Clay minerals are widespread in natural systems and have been widely used for the removal of\rpollutants. In this study, natural expanded vermiculite was used in adsorption tests to remove\rammonium nitrogen from landfill leachate. The modification of vermiculite was carried out using\rNaOH and HCl, and for both modifications the best concentration was 0.1 mol/L. The results produced\rby XRD (X-ray diffraction) showed that Al replaced K after modification of the vermiculite\rusing HCl and that Mg and Na replaced K after modification using NaOH. It was observed that the\radsorption capacity increased as the percentage in mass of K diminished. The Langmuir is the isotherm\rthat presents the best fit of the data, and the values of RL (the Langmuir coefficient) suggest\rthat the adsorption is linear. The thermodynamic parameters indicate that the process is spontaneous\rand endothermic, that there is a high affinity between the adsorbate and the adsorbent, and\rthat physical adsorption is prevalent.