Thermodynamics, Kinetics, and Regeneration Studies for Adsorption of Cr(VI) from Aqueous Solutions using Modified Cellulose as Adsorbent

Cellulose adsorbent was prepared by ATRP grafting of glycidyl methacrylate onto a cellulose backbone with subsequent functionalization with ethanediamine, and then used for the removal of Cr(VI) from aqueous solution. Batch experiments were carried out to investigate the effects of initial pH and initial Cr(VI) concentration on the adsorption performance. The optimum pH for adsorption of Cr(VI) ranged from 2 to 3, and the maximum uptake of Cr(VI) from solution was 500 mg/g at pH 3.0 and 50 degrees C. Langmuir and Freundlich isotherms were applied to the adsorption process, and the thermodynamic parameters were calculated. The results showed that the sorption process to be feasible, spontaneous, and endothermic. Kinetics studies revealed that the pseudo-second-order kinetic model fitted well with the experimental data and the intra-particle diffusion was not the only rate-determining step for Cr(VI) sorption onto adsorbent. The cellulose adsorbent before and after Cr(VI) adsorption were characterized using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). Regeneration of cellulose adsorbent loaded with Cr(VI) can be achieved by treating with 2.0M NaOH.