Treatment of gaseous hydrochloric acid with magnesium–aluminum oxide using batch operation

We have examined the treatment of gaseous hydrochloric acid (HCl) generated from industrial waste incinerators by using magnesium–aluminum (Mg–Al) oxide obtained from Mg–Al layered double hydroxide (Mg–Al LDH). The HCl removal behaviors with Mg–Al oxide and MgO were found to be similar. HCl removal with Mg–Al oxide increased until 3 h due to the production of MgCl2 by the reaction of HCl with MgO property in the Mg–Al oxide, while it decreased from 3 to 12 h due to the production of Mg2(OH)3Cl with the release of HCl. Further, from 12 to 72 h, the HCl removal progressed due to Mg–Al LDH reconstruction and Mg2(OH)3Cl production. The Mg–Al LDH reconstruction was found to be slower than the MgCl2 production. The reaction of gaseous HCl with the Mg–Al oxide surface is probably easier than its diffusion into Mg–Al oxide. In this study, we have obtained basic data for our proposed treatment method to remove gaseous HCl from incinerated waste in batch reactors.