A study of the method of using green copperas (FeSO4.7H2O), sodium silicate (Na2SiO3), concentrated sulphuric acid (H2SO4) for inorganic polymer flocculant polyferric silicate sulfate (PFSS) is conducted. The effects of w(SiO2%) in Na2SiO3 solution, n(Fe)(Si), silicic acid activated time and pH value on the synthesis of PFSS are investigated. The method of preparing PFSS includes following steps: (i) preparation of polyferric sulfate (PFS); (ii) preparation of polymeric silicic acid; (iii) PFS mixture with polymeric silicic acid at a given condition. According to this study, with 0.3ml/L PFSS for treatment of raw water from the Yangtze River, removal rate of turbidity and permanganate index are up to 95% and 90% respectively. The optimum synthesizing parameters of PFSS are: w(SiO2%)=2.0%, n(Fe)(Si)=10:1, silicic acid activated time=10hours.
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