Preparation of polymeric phosphate aluminum-ferric chloride (PPAFC) and its application in humic acid removal

Polymeric phosphate aluminum-ferric chloride (PPAFC) in this study was prepared. In order to obtain the optimum conditions for preparation of PPAFC, resulting in a better turbidity removal efficiency, parameters such as the molar ratio of Al/Fe, P/(Al+Fe), OH/(Al+Fe) as well as the reaction temperature were examined. Results showed that the optimal synthetic conditions were Al/Fe of 6:4, P/(Al+ Fe) of 1:6, OH/(Al+Fe) of 0.6 and reaction temperature of 50 °C. Under this condition, the maximum removal efficiency of turbidity of 99.7% could be achieved. PPAFC was characterized by the infrared spectroscopy (IR spectroscopy) and scanning electron microscopy (SEM). The effects of PPAFC dosage, pH value, initial concentration of humic acid and anions SO42on humic acid removal were studied, which indicated that the maximum removal efficiency of humic acid was 99.1% with the optimum flocculant dosage at pH 4.0, and that there was no anions coexisted.