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

Mg − Al layered double hydroxide intercalated with CO32– (CO3·Mg − Al LDH) was successfully used to remove SO2 from a gas mixture at 140, 170, and 200 °C. The removal of SO2 with CO3·Mg − Al LDH occurred via surface adsorption of SO2 and anion exchange between CO32– in the interlayer of Mg − Al LDH and SO2 from the gas mixture. The removal of SO2 followed the order of Ca(OH)2 > CO3·Mg − Al LDH (Mg/Al = 2) > CO3·Mg − Al LDH (Mg/Al = 4). The removal of SO2 also followed the order of CO3·Mg − Al LDH > Mg(OH)2 > SO4·Mg − Al LDH. CO3·Mg − Al LDH was regenerated from SO4·Mg-Al LDH using a Na2CO3 solution through anion exchange between SO42− and CO32−, leading to its recyclability for removal of SO2 from a gas mixture three times, demonstrating the feasibility of recycling the material.