Polymerization Of Cationic Polyacrylamide P(AM-MAPTAC) Resistant To Acid-alkali And Its Flocculation Performance Study

In recent years,with the development of social and economy,China's sewage production increased year by year,followed by a substantial increase in the amount of sludge,sludge effective treatment and proper disposal has become an environmental issue that can't be ignored.Sludge reduction is the prerequisite and key to the sludge treatment process,it determines the subsequent transport,stabilization and final disposal of the sludge directly.Sludge dewatering is the common way of sludge reduction.Chemical conditioning method by adding chemicals in the sludge,can effectively improve the surface properties of sludge particles,so that sludge is easy to dehydrate.As the most common chemical conditioning agent,the flocculant can multiply and flocculate the sludge particles by electric neutralization and adsorption bridging to reduce the specific resistance of sludge,thus effectively improving the sludge dewatering performance.Cationic polyacrylamide(CPAM)flocculant can be widely used in various water treatment and sludge dewatering treatment because of its high positive charge density,high molecular weight,low cost and less residual toxicity.However,the existing CPAM flocculant have shortcomings in terms of molecular weight,flocculation effect and hydrolysis performance.Therefore,it is of great significance to prepare a new CPAM with high molecular weight,good solubility and wide application by finding a new preparation method,optimizing the process conditions and exploring the structural characteristics of CPAM.Cationic polyacrylamide named P(AM-MAPTAC)initiated by UV was synthesized in this paper with methacrylamide propyltrimethyl ammonium chloride(MAPTAC)and acrylamide(AM)as monomers.The effects of the reaction conditions on the intrinsic viscosity and conversion of the polymerization products were discussed by single-factor and response surface experiment.Results showed that the optimum conditions were as follows: the reaction pH 4.75,initiator concentration 0.07%,EDTA-2Na concentration 0.20%,MATPAC concentration 20mol%,illumination time 60 min.The intrinsic viscosity of P(AM-MAPTAC)prepared under optimized conditions is up to 14.90 dL/g and the molecular weight is 7.42 million;The sequence of the factors which impact the intrinsic viscosity of P(AM-MAPTAC)is illumination time,the reaction pH,initiator concentration,MATPAC concentration,EDTA-2Na concentration.FTIR,~1H-NMR,SEM and TG/DSC of the P(AM-MAPTAC)were characterized.Results showed that AM and MAPTAC were successfully polymerized,and the polymerization product is P(AM-MAPTAC);The surface of the polymerization product has convex and microporous structure,which leads to its large surface area,good solubility and flocculation performance;The P(AM-MAPTAC)is very stable at room temperature and is not easily decomposed.P(AM-MAPTAC)was applied to the dewatering treatment of municipal sludge and dyeing sludge,and the effects of P(AM-MAPTAC)dosage,intrinsic viscosity,cationic degree and sludge pH on the sludge dewatering performance were discussed.The results showed that when the dosage of P(AM-MAPTAC)was 40mg/L,the intrinsic viscosity of P(AM-MAPTAC)was 14.90dL/g,the cationic degree was 25% and the pH value was 6,the municipal sludge dewatering performance was the best,while the dyeing sludge got the best dewatering performance at pH=10.0.By comparing the homemade flocculant P(AM-MAPTAC)and commercially available flocculant CPAM,results found that homemade P(AM-MAPTAC)is better than the commercially available CPAM and has a wider pH range of applications.