Preparation Of Titanium Salt And Ti-fe Coagulant And Their Properties For Arsenic Removal From Drinking Water

As removal from low-arsenic concentration drinking water treated by coagulation with mixture titanium tetrachloride and titanium sulfate as coagulants were studied in this paper, the preparation of them was also mentioned. Without any pre-oxidation process, the residual concentration of As (Ⅲ) after treated by the coagulant (concentration of25mg/L) was less than4μg/L. Operated with rapid water dynamics will get the better efficiency for As (Ⅲ) removal. In the pH range of3-6the variation of As (Ⅲ) removal efficiency was maximum, but the As (Ⅲ) removal declined gradually with the increase of pH while in the alkaline range. Ferrous salts can significantly increase the efficiency of As (Ⅲ) removal by coagulation treatment with mixed titanium salts as coagulant.In addition, an innovative Ti-Fe coagulant for removal of arsenic from drinking water was prepared by hydrolysis method. The effects of pH, dosage of the coagulant, initial concentration of arsenic, hydrodynamic condition and coexistent ions on removal efficiency were discussed. The results show that under the condition of pH=7and dosage of coagulant10mg/L, the residual concentration of arsenic in treated water was8.44μg/L (lower than10μg/L) with initial concentration of arsenic at0.150mg/L. There is still very high removal rate achieved89.81%with the dosage of coagulant10mg/L under a high concentration of As (Ⅲ) at0.500mg/L. The hydrodynamic condition has no significant effect on the removal of arsenic. The fitting coagulation pH is6～8. Coexistent ions such as HCO3-and H2PO42-have negative effect on the arsenic removal.