The proportion of polymer is smaller. With the increasing of the basicity of the salt, the proportion of the redissolved polymerization of Al (OH) 3 gradually increases, and the two reaction processes are staggered. Polyaluminum chloride solution PH value is low when the basicity of the salt is low, polyaluminum chloride is a common water treatment agent in the field of sewage treatment. It has the function of flocculation and sedimentation and can quickly achieve the effect of clear water treatment. Discrimination of the quality of Taiyuan Poly aluminum chloride mainly depends on the quality of aluminum oxide content, the other is the basicity of the salt. The solution of polyaluminum chloride samples of different basicity was diluted to an alumina content of 0.1%. This is because during the whole hydrolysis polymerization, it may contain the direct hydrolysis process and the formation of Al (OH) 3 in the dissolution, and the rising rate is also increasing, the polymerization process, aluminum monomer occupy a higher proportion of hydrolysis The polymerization process is dominated by direct hydrolysis polymerization. At this time, the proportion of aluminum monomer gradually decreases, the proportion of polymer gradually increases, and the absorption of OH- by the polymer is relatively slow. The pH of the solution is measured As the basicity of the salt increases