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

Mg-Al layered double hydroxide intercalated with CO32- (CO3 center dot Mg-Al LDH) is effective for treating HCl exhaust gas. HCl reacts with CO32- in CO3 center dot Mg-Al LDH, resulting in the formation of Cl center dot Mg-Al LDH. We propose that CO2 can be used for the desorption of Cl- from Cl center dot Mg-Al LDH to regenerate CO3 center dot Mg-Al LDH. Herein, we studied the desorption of Cl- from Cl center dot Mg-Al LDH by adding water to Cl center dot 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 center dot Mg-Al LDH. Our results show that the added water adhered to Cl center dot 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 center dot Mg-Al LDH, thus desorbing Cl-. (C) 2020 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.