Acid Treatment of Layered Double Hydroxides Containing Carbonate

Carbonate‐containing Mg–Al layered double hydroxides (LDHs) with two different crystallinities were treated with acidic solutions that contain Cl – . Upon treatment with an acetate buffer/NaCl aqueous solution, low‐crystallinity LDH consumed more protons for dissolution of the metal hydroxide layers than did high‐crystallinity LDH, and it showed a lower extent of exchange of interlayer anions for Cl – than high‐crystallinity LDH. Varying washing procedures also resulted in differences in the characteristics of the washed products, such as the presence of Al(OH) 3 and the extent of exchange for Cl – . When chloride‐containing LDHs were dispersed in water, Mg hydroxide species in the LDHs were found to be dissolved to some extent even in water, and Cl – ions in the LDHs were replaced with OH – ions that were formed by the dissolution.