Improvement of polymeric iron chloride (PICl) preparation for coagulation processes.

摘要

Polymeric iron chloride (PICI) was prepared and characterized. Its performance as a coagulant in coagulation was investigated under varying treatment conditions. To prepare various polymeric iron solutions, ferric chloride solutions were partially neutralized by adding NaHCO₃ solution at a range of hydrolysis ratio (0 ≤ B = [OH−]/Fe_T ≤ 2.0) under different base addition rates, iron(III) concentrations, and temperature. Speciation of the prepared solutions was investigated by using the photon correlation spectroscopy (PCS) technique and ferron method. Results indicated that it is possible to produce a stable polymer with a yield of ∼80% and a mean size of ∼5 nm at room temperature. Extensive jar tests were conducted using synthetic waters containing model colloids and natural organic matter (NOM). Coagulation of synthetic model water with several PICIs was compared to simple ferric chloride under varying conditions of pH and contaminant concentrations. Results indicated that treatable region was broadened for coagulation when using PICI. Findings concerning the improved performance for using PICI in comparison to simple ferric chloride were discussed.