Preparation and Flocculation Performance of Polysilicate Aluminum-Cationic Starch Composite Flocculant

A composite flocculant (PSAS-CS) consisted of cationic starch (CS) and polyaluminum silicate (PSAS) was prepared and used for the flocculation of simulated water samples. The morphology and structure of PSAS-CS were characterized by X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. The effect of flocculation conditions such as the flocculant dosage and the simulated water pH were investigated. The turbidity and color removal rates could reach 97.79% and 98.07% at PSAS-CS dosage of 1.5 mL/L and the simulated water pH of 5–9. Furthermore, the flocculation efficiency of PSAS-CS was compared with PSAS, CS and the starch modified polyaluminum silicate at different dosage. The results indicated that PSAS-CS showed the highest flocculation efficiency due to its plentiful of positive charges and extended molecular chain. Moreover, the removal rate of PSAS-CS could remain 85% at a low dosage of 0.2 mL/L.