A preparation method for high molecular weight cationic polyacrylamide(CPAM) is reported in this paper.CPAM was prepared by using high purity industrial grade acrylamide with acryloyloxyethyltrimethyl ammonium chloride through aqueous copolymerization initiated by VA-O44.The initiator was added all at once and reaction temperature was increased stepwise to complete the polymerization gradually.The effects of reaction variables

such as temperature

reaction time

concentration of monomer and ratio of monomer on the molecular weight of product CPAM were investigated in detail.The optimum conditions were as follows: initial temperature 39℃

reaction time 5 h

monomer concentration 30% and monomer ratio of acrylamide(AM): acryloyloxyethyl trimethyl ammonium chloride(DAC) 2.3∶1.In addition

the maximum molecular weight of obtained product CPAM reached 10210000.The structure of product was characterized by FTIR.And the coagulation/flocculation process was carried out for treatment

of water containing dimethyl phthalate.The removal rate was compared with polymeric aluminum chloride(PAC)

polymeric ferric sulfate(PFS)

poly diallyl dimethyl ammonium chloride(PDMDAAC) and industry CPAM.During the coagulation/flocculation process

parameters

such as coagulant dosage

pH value

stirring time

and settling time were investigated.The results showed the organic coagulant PDMDAAC

industrial CPAM and self-made CPAM had better coagulation effects than inorganic coagulant PAC and PFS

and the self-made CPAM had the best coagulation effects

with an initial DMP concentration of 0.50 mg·L-1

the addition of a self-made CPAM dosage of 12.5 mg·L-1 and the best removal rate of DMP was 97.3%.