Adsorption of Cr(VI) from aqueous solutions using inorganic clays modified magnetic chitosan adsorbent: Kinetic and thermodynamic study

Abstract

Inorganic clays modified magnetic chitosan adsorbent (ICMMCA) was successfully prepared and systematically characterized in chemical structure and morphology. Effect of variables including initial pH and concentration of Cr(VI) in the solution, adsorption time, adsorption temperature and coexisting ions on the performance of ICMMCA in Cr(VI) removal from water were evaluated. Furthermore, the kinetic and thermodynamic studies were conducted to elucidate the adsorption mechanisms and thermodynamic characteristics of the adsorption process. The results demonstrated that the maximum Cr(VI) adsorption capacity of 94.67 mg/g could be achieved when the adsorbent loading was 1 g/L, the initial concentration of Cr(VI) was 100 mg/L, the adsorption time was 60 min and solution pH was at 5. The adsorption data could be well fitted by the Freundlich isotherm model. The thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic in nature. The adsorption process could be described by the pseudo-second-order kinetic model.