Synthesis of magnetic biochar/carbonate intercalated Mg–Al layered double hydroxides for enhanced Cd(II) removal from aqueous solution
Qi Lv, Haixia Wang, Mingliang Zhang, Junbing Xue, Jie Yang
Abstract
ABSTRACT Magnetic wheat straw biochar/Mg–Al layered double hydroxides (LDH) composites were prepared for Cd(II) removal from aqueous solution, and the adsorption performance and mechanisms were investigated. The results showed that magnetic biochar/carbonate intercalated Mg–Al LDH (MB/LDH-CO 3 2– ) exhibited excellent performance for Cd(II) removal, evidenced by the order of maximum removal capacities (MB/LDH-CO 3 2– (54.14 mg/g) > LDH-CO 3 2– (39.03 mg/g) > MB/LDH (35.25 mg/g) > LDH (27.65 mg/g) > BC (14.50 mg/g)). Carbonate anion intercalation with LDH increased the Cd(II) adsorption capacity, and decorating LDH-CO 3 2– with biochar further improved the adsorption performance because of the biochar internal space supplying a large reactive area. Based on X-ray diffraction and Fourier-transform infrared spectroscopy analyses, the adsorption mechanisms on Cd(II) efficient removal by MB/LDH-CO 3 2– were precipitation of CdCO 3 , surface adsorption, surface complexation, and isomorphic substitution of Mg(II). Magnetic composites also improved the efficiency of separation from suspension after Cd(II) adsorption using a magnet. The results suggested that MB/LDH-CO 3 2– could be served as a potential material for efficient removal of Cd(II) from aqueous solution.