| With the diminution of fresh water resource and focusing on the environmental protection, flocculants played more and more important roles all over the world. It is well known that the use of flocculants can improve the efficiency of solid/liquid separation unit operations in a wide range of industrial applications. Water-soluble cationic polyacrylamide can be used as efficient flocculants for many disperse systems such as water treatment, paper-making, mineral processing and other fields.It is desirable to synthesize the hydrophobic polymeric flocculants with cationic charges to improve the flocculation performance of domestic flocculants. In this paper, we developed cationic polyacrylamide flocculants for water treatment. Initiated by multi-initiating system consisting of redox system, azo-compound and co-initiator, the copolymerization of acrylamide and cationic monomers has been realized through radical copolymerization in water solution. In this paper, the molecular weight of polyacrylamide is up to 2.276 X 107 and the mass fraction of cationic monomer can be adjusted from 1% to 50%, which is an important innovation in synthesis of cationic polyacrylamide flocculants.The factors which influence the polymerization such as pH, concentration of initiator, concentration of monomer, temperature of initiation, dosage of co-initiator, carbamide, sodium ethylene diamine tetracetate acid and span-20 were particularly investigated. By orthogonal experimental design, the optimum technical parameters in acrylamide polymerization were confirmed.concentration of initiator: 60ppmconcentration of monomer: 20 %temperature of initiation: 10 ppmconcentration of carbamide: 100 ppmconcentration of span-20: 100 ppmpH: 8concentration of chain propagation agent: 600 ppmconcentration of solium ethylene diamine tetracetate: 100 ppmconcentration of azo-compound: 80 ppmUnder the condition, the molecular weight of polyacrylamide can reach 22.76 million.
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