Desorption of Cl−from Mg-Al layered double hydroxide intercalated with Cl−using CO2gas and water

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 CO2can 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 CO2into 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 CO2in 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−.