Study on Preparation and Flocculation Properties of Inorganic Polymer Flocculant Polyferric Silicate Sulfate (PFSS)

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)/n(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)/n(Si)=10:1, silicic acid activated time=10hours.