Synthesis of layered zinc hydroxide chlorides in the presence of Al(III)

Zinc hydroxide chloride particles were synthesized by hydrolysis of ZnCl2 solutions dissolving AlCl3 at different atomic Al/Zn ratios from 0 to 1.0 and characterized by various techniques. Increasing Al/Zn ratio changed the crystal phases of the products as ZnO→ZnO+ZHC (Zn5(OH)8Cl2·H2O)→ZHC→LDH (layered double hydroxides, Zn–Al–Cl) and the particle morphology as agglomerates (ZnO)→fine particles (ZnO)→plates (ZHC)+rods (ZnO)→plates (ZHC)→plates (LDH). The atomic Cl/Zn ratios of LDH particles formed at Al/Zn⩾0.3 were ca. 0.3 despite the increase of Al/Zn ratio, being due to the intercalation of CO32− into the LDH crystal. The OH− content of LDH estimated by TG was reduced by the deprotonation of OH− to counteract the excess positive charge produced by replacing Zn(II) with Al(III). ZHC exhibited a high adsorption selectivity of H2O.