Fabrication of a cationic polysaccharide for high performance flocculation

A cationic polysaccharide (CDCS) derived from dextran and chitosan was fabricated by crosslinking method as an eco-friendly flocculant. The flocculant was characterized by thermogravimetric analysis and Fourier transform infrared spectroscopy. Influences of temperature, pH and flocculant dosage on flocculation efficiency were examined. The CDCS presented enhanced high flocculation properties in a wide pH range conditions. In kaolin suspension, when pH was in the rang of 3–7, the flocculation efficiency was over 96.9% with dosage below 5   mg/L. In alkaline condition, it also presented a high flocculation efficiency of 98.2% (pH   =   9) and 93.7% (pH   =   11) with a low dosage of 7 and 17   mg/L, respectively. The flocculation efficiency decreased as the temperature rose from 10 to 40 ∘ C. For actual wastewater treatment, the CDCS flocculant performed much better than commercial polyacrylamide and ferric sulfate. It removed 97.7% of the solid suspended particles in the wastewater. The flocculant mechanism study suggested charge neutralization, adsorption bridging and sweeping flocculant mechanisms were included in the flocculation process. The flocculant CDCS exhibited a broad prospects for wastewater treatment.