Effects of pH and concentration on ability of Cl~- and NO_3~- to intercalate into a hydrotalcite-like compound during its synthesis

摘要

In this study, we confirmed that the characteristics of anion intercalation into the interlayer of a hydrotalcite-like compound (HT) during synthesis are similar to those of the anion-exchange reaction of HTs as well as the reconstruction reaction of HTs from Mg-Al oxide. We demonstrated that (i) Cl~-, which has a higher charge density than NO_3~-, more easily reacted with Mg and Al species to form HT structure, resulting in greater intercalation of Cl~- into the HT interlayer; and (ii) for HTs with lower Mg: Al molar ratios, OH~-, which has a higher charge density than Cl~- and NO_3~-, was more likely to interact with Mg and Al species to form HT structure, blocking the intercalation of Cl~- and NO_3~-. Furthermore, we showed that high concentrations of Cl~- and NO_3~- in solution regulated their intercalation into the HT interlayer. The high activity of Cl~- and NO_3~- in solution would facilitate the anions' reactions with Mg and Al species to form HTs, resulting in a high degree of anion intercalation into the interlayer of HTs.