Synthesis of magMCM-41 with rice husk silica as cadmium sorbent from aqueous solutions: parameters’ optimization by response surface methodology

ABSTRACTThe magnetic mesoporous silica of magMCM-41 with large surface area (695 m2 g−1) and high magnetization (10.79 emu g−1) was synthesized using extracted amorphous silica from rice husk. The synthesized materials were applied for adsorption of Cd(II) ions from aqueous solution in batch operation systems. A highly selective adsorbent was obtained by grafting 3-aminopropyltrimethoxysilane on the pores of the magMCM-41 in which the adsorption capacity of Cd(II) ions increased from 41.8 to 86 mg g−1, under the same conditions. A total of 20 sets of experiments were planned by the central composite design under response surface methodology. The effects of three independent variables pH, initial Cd(II) ion concentration and sorbent dosage were investigated on the adsorption capacity (qe) and removal efficiency (R) of cadmium. The best responses for Cd(II) adsorption capacity and removal efficiency were 493.21 mg g−1 and 60.25%, respectively, which was achieved at pH of 5.05, sorbent dosage of 0.1 g L−1 an...