Study On The Species, Configuration, And Coagulation Properties Of Polyaluminum Chloride Prepared By Electrolysis Process

A novel method concerning an electrolysis process for preparation of PAC was developed. The PAC contains high content of Al 13 that was considered to be the most effective flocculating component, hi addition, the method is suitable for producing PAC on the spot and a batch production. It has a wide utilizing prospect and an important practical value. This paper aimed at providing basic theory and technique for Electrolysis-PAC's R&D and practical use.To optimize the quality of Electrolysis-PAC and provide ideal flocculants for next experiments, E-PACs, with different concentration of Al(III) and basicity, were prepared in lab. During the preparation, temperature, pH, and basicity of electrolyte were monitored. The results showed that, these parameters at first increased gradually and then tended towards a steady data with the extension of electrolysis process, and the transforming progress of aluminum species could be set apart three phases according to basicity.The species distribution of hydrolyzed Al(III), aggregation configuration, the characteristics of crystal of E-PAC were characterized by using Al-Ferron time complex colorimetric method, 27 Al NMR spectroscopy, and transmission electron micrograph (TEM). The results illuminated that the predominant aluminum species of E-PAC was Aln (Alb) or small aggregated Aln, and the quality of E-PAC was more outstanding than ordinary PACs. The content of Alb characterized by using Al-Ferron time complex colorimetric method and Al13 characterized by using 27 Al NMR spectroscopy was equivalent on the whole.The stability of Alb in E-PAC was studied. The results showed that the content of Alb could hold the line within a month, and the stability of Alb was significantly affected by concentration of aluminum and basicity. Along with the increase of deposit time there was a positive correlativity between the content of Alb and pH.The coagulation behavior of E-PAC was investigated. The results indicated that coagulation efficiency was enhanced by high content of Aln species because of its characteristics of higher positive charge (+7) and strong binding ability. E-PAC was more effective in removing SS, RT, and oil from water and wastewater than other coagulants. There was a negative correlativity between the content of residual aluminum in finished water and coagulation efficiency.