Synthesis, characterization, and coagulation of polymeric ferric sulfate

This paper proposes a new approach to synthesize polymeric ferric sulfate (PFS). It was found that the basicity and stability of the synthesized PFS varied with the quantity of sulfuric acid used. The minimum amount of sulfuric acid needed for the synthesis of PFS to insure a residual Fe2+ concentration in the product lower than 0.1 wt% is about 31.0 wt% of the stoichiometric requirement. However, to produce a stable product which can be stored for six months, the amount of sulfuric acid should be 51.7 and 62.0 wt% of the stoichiometric requirement for PFS produced at 55 and 85degreesC, respectively. The structure of PFS depended on the synthesis temperature, as observed through x-ray diffraction and transmission electron microscopy. A comparison of the coagulation performance of PFS and ferric sulfate (FS) showed that PFS is, in general, more effective than FS in reducing the turbidity of Kaolinite suspensions for various conditions.