Modification of Natural Clay Surface with Manganese-Oxide for Removal of Cadmium(II) Ion from Aqueous Solution

Abstract

Natural clay (NC) and its surface modified with manganese oxide (MnO-NC) was assessed for removal of Cd (II) ion by batch adsorptive process. The surface modification of NC was chemically prepared with manganese chloride in basic solution by simple procedure, resulting in larger surface area than raw material by about 10-times. FT-IR spectra and SEM photograph showed the unique characteristic of MnO-NC after chemically surface modification with MnO2 particles successfully set down onto the NC surface. Under optimum conditions as a function of solution pH of 6.0, adsorbent dose of 5 g/L, contact time of 15 min and initial cadmium concentration of 100 mg/L, the adsorption capacity reach to 30.6 mg/g. By comparing with NC, MnO-NC provides higher adsorptive capability than the one by about 30-times. Based on isotherm estimation, the Langmuir adsorption isotherm showed more suitable for both adsorbents with the best correlation coefficient (r2>0.99) than the Freundlich isotherm. The adsorptive kinetics of Cd (II) onto NC and MnO-NC followed the pseudo-second-order.