Preparation And Flocculating Performance Of Cationic Polyacrylamide Obtained By Inverse Emulsion And Aqueous Dispersion

Cationic poIyacrylamide(CPAM) was synthesized by inverse emulsion and aqueous dispersion polymerization using acrylamide(AM) and methacryloyloxyethyl-trimethyl ammonium chloride(DMC) as monomers. The structure of obtained copolymer was characterized by FT-IR. The copolymer particles were analyzed by Transmission Electronic Mirror and the Laser Particle-size Analyzer. And the flocculating performance of the obtained copolymer in wastewater was investigated.The preparation of cationic polyacrylamide by inverse emulsion polymerization was studied. The influences of the factors, such as type and concentration of emulsifier, type and concentration of initiator, the mass ratio of oxidant to reductant, monomer concentration, pH, reaction temperature, the mass ratio of oil to water, cationic degree, reaction time, N2 inlet time, drying time, drying temperature, type and concentration of increase-chain agent, type and concentration of chelator, on molecular weight, solubility and particle size of copolymer were investigated. And the flocculation performance of the obtained copolymer was evaluated. The obtained optimum conditions were emulsifier (Span-80/Tween-80) concentration 7.3%, initiator (K2S2O8/CH3NaO3S·2H2O) concentration 200 mg-Kg-1, m(oxidant) : m(reductant) =1 : 1, monomer concentration 45%, pH=3, reaction temperature 45°C, cationic degree 25%, m(oil) '. m(water) = 1:2, reaction time 4h, N2 inlet time 30min, drying temperature 40°C, drying time 12h, increase-chain agent concentration 60 mg-Kg-1, EDTA·2Na concentration 2 mg.Kg-1, feeding speed 40~60drops/min and stirring speed 450rpm. Under above conditions, the molecular weight and particle size of copolymer were 339.2×104and about 70 nm respectively. And the obtained optimum conditions for flocculation experiments were dosage of flocculant 0.057%, wastewater pH =6, molecular weight of flocculant 339.2×104 and eationic degree of flocculant 25%. Under above conditions, the transmittance of treated wastewater, the flocculating rate and dewatering rate were 92.5%, 62.2% and 82% respectively.Polymethacryloyloxyethyltrimethyl ammonium chloride (PDMC) was prepared by aqueous solution polymerization using azo-compounds (VA-044) as initiator, which could be used as a stabilizer in aqueous dispersion polymerization. The influences of the factors, such as initiator concentration, reaction temperature, DMC concentration, pH, reaction time, drying temperature and drying time, on molecular weight and water-solubility of PDMC were investigated. The obtained optimum conditions were initiator concentration 2500-4000 mg.Kg-1, DMC concentration 60%, pH =5, reaction temperature 45°C~75°C, drying temperature 50°C~60°C and drying time l0<1lh. The structure of obtained PDMC was characterized by FT-IR.The preparation of eationic polyacrylamide by aqueous dispersion polymerization was studied. The influences of the factors, such as type and concentration of inorganic salt, molecular weight and concentration of stabilizer, type and concentration of initiator, tertiary butyl alcohol concentration, reaction temperature, pH, monomer concentration, eationic degree and reaction time, on molecular weight and particle size of copolymer were investigated. And the effects of pH and temperature of wastewater, the molecular weight, the dosage and eationic degree of copolymer on flocculating results were studied. The obtained optimum conditions were (NH4)2SO4 concentration 30.0%, molecular weight of PDMC 40×104~50xl04, PDMC concentration 2.5%, initiator concentration 150 mg·Kg-1, v(TBA):v(H2O) =0.2:1, reaction temperature 50°C, pH =7, monomer concentration 10%, eationic degree 10%, reaction time 8h. Under above conditions, the molecular weight and particle size of copolymer were 580.2×104 and about 200 nm respectively. And the obtained optimum conditions for flocculation experiments were wastewater dosage of flocculant 0.020%, pH =5, molecular weight of flocculant 550x 104 and eationic degree of flocculant 12%. Under above conditions, the transmittance of treated wastewater, the flocculating rate and dewatering rate were 97.7%, 64.2% and 85% respectively.