The Synthesize And Coagulative Performance Of The Composite Coagulant PFS-PDM

Polydiallyldimethylammonium chloride(PDMDAAC) is a kind of cationic organic high-molecular compound. As a kind of flocculating agent,PDMDAAC is water miscible,highly effective and with low mammalian toxicity. In this paper, polymerization of DMDAAC was initiated by ammonium persulfate(APS),and compounded with polyferrie sulfate(PFS) to prepare composite flocculants. The application properties of composite flocculants were studied systematically.The effects of each processing factors such as the amounts of monomer, initiator,chelating agent and maintaining temperature,etc. on the product PDMDAAC's intrinsic viscosity and conversion rate were studied, the influencing trend of the factors are obtained.The best processing condition was:the amount of ammonium persulfate used for the reactant weight 0.46%(weight percent based on monomer weight), the amount of chelating agent weight 0.006%(weight percent based on monomer weight),adjusted reaction solution pH to 6.0, the polymerization wase carried out by heating in the waterbath of 55℃for 4 hours, thermal insulation for another 2 hours.And the highest value of intrinsic viseosity of the obtained product PDMDAAC was 1.73 dL/g,the monomer conversion was 83.7%.PFS and the composite coagulant of PFS-PDM1.4 was introduced to evaluate the effect of clarification on kaoline soliquoid. The experimental results showed that the removal efficiency of turbidity from kaoline soliquoid by the composite coagulant was higher than PFS at condition of lower dosage. Along with the increase of dosage, the turbidity removal rates of PFS was slightly higher than PFS-PDM1.4; When the pH ranges from 6.0-9.0, tubidity was removed effectively with the coagulants of PFS(Fe%=11%) and PFS-PDM1.4, but the efficiency was almost the same when the dosage of the coagulant increased; PFS-PDM1.4 showed better coagulation performance when ph value was 5.0; for lower turbidity kaoline soliquoid, composite coagulant of PFS-PDM1.4 did not show obvious advantages compared to PFS.The tests self-made enhanced coagulation treatment of micro-pollution Liuxi River water was studied with the composite coagulant of PFS-PDM. The treatment efficiency of the Liuxi River water with PFS and PFS-PDM were compared and analyzed. The experimental results showed that the removal efficiency of turbidity, UV254, and algae from micro-polluted source water by the composite coagulant was higher than PFS. The removal efficiency of turbidity, algae and UV254 increased by 22.1%,19.5% and 14.9% respectively when PFS-PDM dosage was 3mg/L. The composite coagulant showed better enhanced coagulation performance.The treatment of papermaking wastewater with PFS and PFS-PDM1.4 was compared and analyzed. The experimental results showed that, at the dosage of 150mg/L, the removal rates of turbidity, CODcr can reach 94.5%,46.9%, which increased by 5.2% and 3.3% respectively compared to PFS, besides,PFS-PDM even have stronger adaptability,and when the wastewater's pH value was 8.0, PFS-PDM can reach the best removal rates of CODCr. The composite coagulant of PFS-PDM showed some advantages in the treatment of papermaking wastewater.