Mg−Al layered double hydroxide intercalated with CO32– and its recyclability for treatment of SO2.

Mg − Al layered double hydroxide intercalated with CO 3 2– (CO 3 ·Mg − Al LDH) was successfully used to remove SO 2 from a gas mixture at 140, 170, and 200 °C. The removal of SO 2 with CO 3 ·Mg − Al LDH occurred via surface adsorption of SO 2 and anion exchange between CO 3 2– in the interlayer of Mg − Al LDH and SO 2 from the gas mixture. The removal of SO 2 followed the order of Ca(OH) 2 > CO 3 ·Mg − Al LDH (Mg/Al = 2) > CO 3 ·Mg − Al LDH (Mg/Al = 4). The removal of SO 2 also followed the order of CO 3 ·Mg − Al LDH > Mg(OH) 2 > SO 4 ·Mg − Al LDH. CO 3 ·Mg − Al LDH was regenerated from SO 4 ·Mg-Al LDH using a Na 2 CO 3 solution through anion exchange between SO 4 2− and CO 3 2−, leading to its recyclability for removal of SO 2 from a gas mixture three times, demonstrating the feasibility of recycling the material. Unlabelled Image • This study deals with the development of CO 3 ·Mg − Al LDH for the removal of SO 2. • The SO 2 removal increased with increasing temperature and SO 2 concentration. • The removal proceeds under mass transfer control rather than surface chemical reaction control. [ABSTRACT FROM AUTHOR]