Optimized preparation and performance evaluation of a bifunctional chitosan-modified flocculant

In view of the diversification of pollutants in current sewage, further improving the application efficiency of water treatment agents and realizing multi-functionalization are important directions for the research of water treatment agents. In this paper, on the basis of the natural polymer flocculant chitosan, MAPTAC and AM were used as modified monomers to improve its solubility and also enhance its flocculation and bactericidal properties. Furthermore, the preparation conditions of chitosan flocculant poly(CTS-g-AM-MAPTAC) were optimized by response surface methodology, and its flocculation and sterilization functions were evaluated in detail. The experimental results showed that the significance order of the factors in the preparation process was illumination time, mass ratio of total monomer to chitosan, molar ratio of monomers, and initiator concentration. The optimum conditions for preparing poly(CTS-g-AM-MAPTAC) were 6 moL L^-1 for initiator concentration, 4 for mass ratio of total monomer to chitosan, 25% for monomer molar ratio, and 60 min for illumination time. The intrinsic viscosity and grafting rate of poly(CTS-g-AM-MAPTAC) prepared under optimum conditions were 5.4965 dL g^-1 and 220.34%. The obtained poly(CTS-g-AM-MAPTAC) had good solubility, which could fully expose the active sites in wastewater with different acidity and had good flocculation effect. The performance evaluation results showed that the flocculant had a good combination of flocculation and sterilization, and had the advantages of high turbidity removal and sterilization efficiency, good biodegradability and low reagent consumption.