Poly aluminum Chloride(PAC) is a water purification material. Poly aluminium chloride is an inorganic polymer coagulant. Referred to as PAC. Poly aluminum chloride is an inorganic polymer water treatment agent which has a large molecular weight and a high charge due to the bridging action of hydroxide ions and the polymerization of polyvalent anions. Morphologically, aluminum chlorohydrate can be divided into solid PAC and liquid PAC. Solid PAC are divided into brown, beige, golden yellow and white according to their colours. PAC liquid can be colorless transparent, yellowish, light yellow to yellowish brown. Different colours of polyaluminium chloride have great differences in application and production technology