Preparation Of The Pfs And Modified

Polyferric sulfate(PFS) attracts people's attention for its excellent coagulant performance. It is very important to synthesis PFS with simple process and low cost. Liquid PFS, solid PFS and solid modified PFS were prepared from ferrous sulfate, sulfuric acid and sodium chlorate, and the application to the industrial wastewater treatment were also studied.Liquid PFS was prepared by air-oxidant method. The effects of the material composition, reaction temperature, pH value on liquid PFS quality were studied, and the optimum preparation condition was obtained. The molar ratio of FeSO4·7H2O to H2SO4 is 1:0.35-0.40, pH value is 0.5-1, reaction temperature is 60℃, NaClO3 is added by 7h oxidization with air. This method can reduce 80% consumption of oxidant. The removal rate of COD and turbidity are 65.2% and 91.4% respectively with the addition of 146 mg·L-1 in the treatment of dye wastewater.Effects of the molar ratio of raw materials, reaction temperature, reaction time, aging time and drying temperature on the quality of solid PFS were investigated. The optimality preparation conditions are as follows:the molar ratio of FeSO4·7H2O to H2SO4 is 1:0.23, reaction temperature is 54℃, reaction time is 90 min, drying temperature is 54～59℃. The new technology can reduce energy cost of 2331 kJ·kg-1 compared with the direct evaporation from liquid PFS. The removal rates of COD and turbidity are 82.1% and 98.3% respectively with the addition of 100 mg·L-1 in the treatment of dope wastewater.A kind of modified PFS is prepared by intruducing Mn2+ into PFS. Effects of the molar ratio of Fe to Mn, reaction temperature, and the dosage of H2SO4 on the flocculation performance of solid modified PFS were investigated. The optimality preparation conditions are as follows: the amount of FeSO4·7H2O is 27.8g, MnSO4 is 8.45g, H2SO4 is 1.5ml, reaction temperature is 54℃. The flocculation performances of solid modified PFS and solid unmodified PFS were compared in the treatment of dye wastewater, dope wastewater and papermaking wastewater, with the flocculant dosage of 150 mg·L-1,100 mg·L-1 and 150 mg·L-1, respectively in the above three kind of wastewater, for solid modified PFS, the removal rate of COD is 71.3%,87.6% and 73.7%, respectively, the removal rate of turbidity is 96.5% ,99.7% and 91.3%, respectively. In the treatment of dyestuff wastewater, dope wastewater with solid PFS, the removal rate of COD is 65.8% and 82.1%, respectively, the removal rate of turbidity is 93.1% and 98.3%, respectively. The results indicate that the flocculation performance of modified solid PFS is better than that of unmodified solid PFS in the treatment of dye wastewater, dope wastewater and papermaking wastewater.