What is Poly Aluminium Chloride?
Chemical equation:
① HCl  +  Al(OH)3  →  AlCl3  +H2O
② AlCl3  +  Al2O3.CaO  + H2O →  [Al2(OH)nCl6-n]m
③ Polyauminium chloride molecular formula is [Al2(OH)nCl6-n]m
n=0, it is AlCl3;
n=6, it is Al(OH)3.
n=1~5, it is Polyaluminium chloride.
n is related to the basicity of the Poly Aluminium Chloride.