| The shortage of water resources and the pollution of water environment have become the important factors that restrict national economic and social development of our country. Traditional method of water treatment is to remove pollutants by flocculation and to eliminate biological contamination by adding fungicide, but the two steps are always conducted separately, resulting in a series of problems, such as process and operation complicating, and incompatibility of flocculation and sterilization, etc.In this paper, Three kinds of flocculation-sterilization double-effect polymers were designed and synthesised as the followings: (1) The monomer diallylmethylbenzylammonium chloride (DAMABC) was synthesized using methylamine, allyl chloride and NaOH as raw materials, then initiated by ammonium peroxydisulfate (APS) to prepare poly(diallylmethylbenzylammonium chloride) (PDAMABC); (2) N,N-diallyl-N-carbobutoxymethylammoniumchloride (DACBMAC) was synthesized using diallylamine, butyl chloroacetate, K2CO3 and hydrochloric acid as raw materials, next Poly(N,N-diallyl-N-carbobutoxymethylammonium chloride) (PDACBMAC) was prepared using DACBMAC as monomer and APS as initiator in aqueous solution; (3) Poly(N,N-diallyl-N-carbobutoxymethylammonium chloride) (PDAMAC) was synthesized using diallylmethylamine hydrochloride (DAMAC) which was prepared from diallylmethylamine and hydrochloric acid as monomer and APS as initiator, then reacted with (dodecyldimethyl-2-hydroxypropane)ammonium chloride (CHPDDAC) in mixed water-alcohol solvent to synthesize a kind of polymer with dodecyl (PDAMADC). The suitable conditions were determined and the structures of in-process products and products were characterized by FT-IR, 1HNMR and elementary analysis.Diatomite suspension with the turbidity of 201 NTU was chosen as the object to test the flocculation property of the synthetic products, which was compared with poly (dimethyl diallyl ammonium chloride) (PDMDAAC). The results show that the higher the intrinsic viscosity of the products is, the better the effects of the turbidity removal are; PDAMABC and PDAMADC are applied in a wide pH range from 4 to 10, while PDACBMAC is suitable to be used under neutral or weakly acidic conditions. The removal rate of turbidity is up to 87.72% when the dosage of PDAMABC at 0.3 mg/L, and the removal rates reach 93.13% and 90.58%, respectively, when the dosage of PDAMADC and PDACBMAC is at 0.4mg/L separately, which are better than the optimal removal rate 82.55% of PDMDAAC.The methods of plate counting and MPN were used to study the sterilization property against Escherichia coli (E.coli), sulfate-reducing bacteria (SRB) and iron bacteria (IB), respectively, and compared with PDMDAAC and dodecyldimethylbenzylammonium chloride (1227). Antimicrobial mechanism of the products was explored though theβ-D-galactosidase enzyme activity assay. The results show that, the bactericidal rate increases with the increasing of dosage. When the dosage is 50mg/L, bactericidal rates of PDAMADC and PDACBMAC against E.coli are 98.31% and 97.52%, respectively, better than 95.91% of 1227, while the bactericidal rate of PDAMABC is up to 86.70%, slightly higher than 85.40% of PDMDAAC. The bactericidal rate increases with increasing intrinsic viscosity at the same dosage. The optimum bactericidal effect of PDACBMAC reveals when pH in a range of 5.7～7.2, and bactericidal rate decreases rapidly when pH>7.5, but PDAMADC and PDAMABC are less affected by the pH value, whose bactericidal rates change little with increasing pH when pH>6.7. The sterilization effects of the products against SRB and IB show as the following order: PDAMADC>PDACBMAC≈1227>PDAMABC>PDMDAAC. The results of measuring activities of the enzyme ofβ-D-galactosidase indicate that the antimicrobial mechanism of the products is based on a sterilization action.The products had been applied in the treatment of sewage with a bacterial capacity of 3×103 cfu/mL, turbidity of 113 NTU and COD of 203 mg/L. The results show that satisfactory effect can be achieved when the dosage of the products is at 11mg/L, and the bactericidal rates of PDAMADC, PDACBMAC and PDAMABC are 96.31%, 93.42% and 87.78%, respectively, the corresponding turbidity removal rates are 89.13%, 87.28% and 85.31%, and the COD removal rates are 72.80%, 70.94% and 68.12%, which are better than those of PDMDAAC and PAM.In short, PDAMADC and PDACBMAC are efficient dual-effect polymers with excellent flocculation and sterilization properties, which could achieve two functions only by flocculation, in addition, making the flocculation and sterilization work in coordination with each other, improving the efficiency of water treatment and simplifying process flow and reducing costs, therefore, they have a good application prospect in water treatment.
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