Template Polymerization Of P(AM-DAC) With New Compound Initiating System

Since the reform and opening policy of C hina, the economy and society has made a rapid development, the emission of wastewater is increasing, and at the same time the problem of sludge treatment and disposal has attracted more and more attention from the public. Flocculants can effectively improve the dewatering performance and reduce filter cake moisture content for in sludge conditioning, especially high molecular weight, positively charged cationic polyacrylamide(CPAM) is widely used in it. However, the existing template polymerization of cationic polyacrylamide has the defect of low molecular weight, bad performance of sludge dewatering, and it will reduce the relative molecular mass to a certain extent. Therefore, to research the template method of further increasing the molecular weight of cationic polyacrylamide is of great significance.In this thesis, the experiment is about the optimized preparation, characterization and application of cationic polyacrylamide P(AM-DAC) with new compound polymerization initiator system, the main contents and conclusions are as follows:(1) Through single factor analysis method, with the relative molecular weight of the polymer and monomer conversion as indexes to investigate the influence of various factors on the polymerization and determine the optimal synthesis conditions: the molar mass ratio of template and cationic monomer T: D(ie, n(PAAS):n(DAC))is 1, the total monomer concentratio n is 30%, DAC mass fraction of 20%, the mass fraction of the compound initiator system is 0.015%(where n((NH4)2S2O8):n(Na HSO3)= 2, m(V044):m((NH4)2S2O8/Na HSO3)= 2), the polymerization reaction system p H is 4, the urea concentration is 0.3%, UV irradiation time is 90 min, under the above conditions, the relative molecular weight of the template polymer of P(AM-DAC)is up to 7.1 million, the conversion is 94.8%. By variance analysis and intuitive analysis of orthogonal experiment shows that the influence of various factors on the template polymer P(AM-DAC) molecular weight of the order: DAC mass fraction> n((NH4) 2S2O8):n(Na HSO3)> m(V-044):m((NH4)2S2O8/Na HSO3)> UV irradiation time> concentration of the compound initiator system > p H value;(2) By infrared spectroscopy(FT-IR) and proton nuclear magnetic resonance spectroscopy(1H-NMR)of the polymerization product shows that the usage of the new compound initiator system does not change the structure of the polymer, and the synthesis products is a copolymer of monomer AM a nd DAC; by differential thermal- analysis-thermo gravimetric analysis(DTA-TGA) can be seen, the polymer at a temperature in the range of 30~210? can not been easily decompo sed,and the polymer product P(AM-DAC) has good thermal stability;(3) Through determining the filter cake moisture content, residual turbidity of the supernatant and specific resistance of filtration by municipal sewage plant sludge dewatering applications, the following results can be obtained: the cationic ratio of 20%, relative molecular mass of 7.1 million, the optima l dosage of template polymer P(AM-DAC)is 20mg/L, the dewatered sludge cake moisture content is 71.43%, the residual turbidity of supernatant is 2.73 NTU, sludge specific resistance is 2.1× 1012m/kg; when the p H value of sewage is 6-8, the sludge dewatering better; By comparing the sludge dewatering effect between template polymerization product and no template polymerization product, the results shows that the template polymerization will indeed increase the electrical capacity of polymer; By examining sludge dewatering effect of two commercial products can be seen, the sludge dewatering performance of homemade cationic polyacrylamide P(AM-DAC)is better than CQ-CPAM and GY-CPAM to a certain extent.(4) The paper mill sludge was adopted as research object, through optimizing the cationic ratio, dosage and p H etc, the optimum sludge dewatering conditions can be got: when the sludge p H is 6, the dosage of polymer P(AM-DAC)which was synthesized under optimum conditions is 80 mg · L-1, paper sludge moisture content decreased to 74.21%, the residual turbidity of supernatant is 3.98 NTU, sludge specific resistance is 2.5 × 1012 m / kg.