The Study On Synthesis And Application Of AM-DMDAAC Copolymer

The organic content of wastes from industrial and daily life has been obviously improved with the development of modernization process. Such aqueous system containing organic compounds or colloids carry negative charges so that it could be feasibly flocculated by using cationic polymer flocculants, therefore, the cationization of flocculants is one of the significant future development in this field. The cationic polyacrylamide(PAM) polymerized from Dimethyldiallylammonium Chloride(DMDAAC) and Acrylamide(AM) is universally applied in the field of water treatment because it is efficient, nontoxic and of high positive charge density.This paper prepared cationic poly dimethyldiallylammonium chloride- acrylamide P(AM-DMDAAC) via aqueous two-phase copolymerization by adopting ammonium persulfate and sodium bisulfite as the redox and polyethylene glycol(PEG) as the dispersant. The reaction condition of copolymerization has been optimized, the related theory of two-phase copolymerization has been investigated, the structure and properties of products from copolymerization has been characterized and applied for simulation of wasted water. Meaningful conclusions can be drawn from the current study.(1) Single-factor experiment was utilized to investigate condition of polymerization and the influence of each factor on relative molecular weight. The cationic degree was also investigated. An orthogonal experiment with 4 factors and 3 parallels(L9(34)) was designed to investigate for finding out the optimal process conditions for preparation of cationic PAM with higher viscosity average molecular weight and cationic degree.(2) Analysis of FTIR spectra for polymer products was carried out to determine whether or not the AM and DMDAAC was successfully copolymerized.(3) The binary differential equation of AM-DMDAAC copolymer was investigated, the activity ratio of the copolymerization was calculated according to K-T method, F-R method and YBR method. Meanwhile F-f curves were plotted with activity ratio for the determination of polymerization type.(4) Liquid-liquid boundary curves, phase separation curves and kinetics curves were plotted according to the investigation of two-phase polymerization system, phase separation and reaction kinetics of AM-DMDAAC, respectively.(5) The final products were applied to the simulation of treatment of wasted water. The influence of cationic degree and viscosity average molecular weight on turbidity rate was investigated by applying the final products to simulating the treatment of wasted water while the influence of each factor on turbidity rate by investigating the single-factor experiment of flocculation reaction conditions. An L9(34) experiment was designed to find out the optimal conditions of flocculation.It can be seen from the single-factor experiment that: the cationic degree firstly increases and then tends to decrease as the amount of initiators and PEG, the ratio of monomers, pH value and the temperature increases. At the meantime, the viscosity average molecular weight has the same variation trend, however, it shows little influence on viscosity average molecular weight when the temperature is in the range of 55℃-65℃ while it tends to fall down as the temperature is higher than 65℃. It can be concluded from the orthogonal experiment that: the resulted P(AM-DMDAAC) has the largest viscosity average molecular weight when the condition is monomer ratio = 6:1, m(PEG)=7g,T=65℃, each initiator =1.6mL,pH=8.5 and the sequence of influence from the single-factor is as follows: pH value > temperature > amount of initiators >monomer ratio. The resulted largest cationic degree of P(AM-DMDAAC) could be as high as 7.465% when the optimal condition is monomer ratio = 7:1, each initiator = 1.6 m L, m(PEG) =7g, T=65℃,pH=7 and the sequence of influence from each factor is as follow: monomer ratio > pH value > temperature > amount of initiator. The turbidity rate of wasted water turns to be higher as the cationic degree and viscosity average molecular weight increases. It can be concluded that the increase of the bentonite initial turbidity would cause the flocculation effect of the polymer products to decrease. The flocculation effect would firstly increase and then decrease as the amount of P(AM-DMDAAC), stirring time, pH value and temperature increases. It can be known from the orthogonal experiment that the wasted water treatment has the optimal result with turbidity rate as high as 96.87% when the condition is the amount of P(AM-DMDAAC) =0.3m L, stirring time =60 min, pH =6 and the temperature = 60℃ and the sequence of influence for single-factor is as follows: amount of P(AM-DMDAAC) >temperature >pH value > stirring time. It is confirmed that AM and DMDAAC have successfully performed copolymerization through analysis of the products. The activity ratio of AM and DMDAAC is calculated to be 1.1208 and 0.7674 through the designed experiments, respectively. The reaction kinetics curves, F-f curves and CPAM-PEG two-phase curves are plotted according to the resulted data of these experiments.