Desorption of Cl− from Mg-Al layered double hydroxide intercalated with Cl− using CO2 gas and water

Abstract

Abstract Mg-Al layered double hydroxide intercalated with CO32− (CO3·Mg-Al LDH) is effective for treating HCl exhaust gas. HCl reacts with CO32− in CO3·Mg-Al LDH, resulting in the formation of Cl·Mg-Al LDH. We propose that CO2 can be used for the desorption of Cl− from Cl·Mg-Al LDH to regenerate CO3·Mg-Al LDH. Herein, we studied the desorption of Cl− from Cl·Mg-Al LDH by adding water to Cl·Mg-Al LDH and blowing CO2 into it. We also analyzed the effects of temperature and water addition speed on the desorption of Cl− from Cl·Mg-Al LDH. Our results show that the added water adhered to Cl·Mg-Al LDH and that CO2 in the gaseous phase was dissolved in this adhered water, thus generating CO32−. Therefore, anion exchange occurred between CO32− and Cl− in the Cl·Mg-Al LDH, thus desorbing Cl−.