Chitosan-modified vermiculite for As(III) adsorption from aqueous solution: Equilibrium, thermodynamic and kinetic studies

This work presents the preparation of chitosan-modified vermiculite (C-mVMT) in a facile wet chemistry process. The potential of C-mVMT was investigated for the adsorption of As(III) ions from an aqueous solution. The effect of the pH of the solution, adsorbent dosage, contact time, and temperature on the adsorption efficiency was studied systematically. The maximum adsorption capacity of rVMT and C-mVMT sorbents for As(III) was determined as 34.9 mg/g and 72.2 mg/g, at pH 5, with a contact time of 30 min and 20 °C. The prepared C-mVMT sorbent exhibited good reusability performance, even after ten cycles. The results obtained from the D-R model revealed that the adsorption process were chemically dominant. Thermodynamic parameters (ΔH° and ΔS°) indicated that, under the studied temperature range, the adsorption of As(III) by C-mVMT was feasible and had a spontaneous and exothermic nature. The kinetic model examinations showed that the adsorption processes followed pseudo-second order kinetics well. Based on all the results, the produced C-mVMT can be evaluated as a potentially cost-effective sorbent for As(III) removal from aqueous solutions.