Photoinitiated Polymerized Chitosan and DMDAAC for Efficient Algae Removal: Preparation, Characterization, and Application

In this study, we used CTS and DMDAAC as raw materials and prepared a novel chitosan graft copolymer, CTS-g-PDMDAAC, through UV initiation in the presence of the photoinitiator VA-044. The synthesis process was systematically optimized, and its structural characteristics and performance in water treatment were evaluated. A single-factor experiment determined the optimal synthesis conditions to be a mass ratio of chitosan to DMDAAC of 1:4, total reactant concentration of 15.5%, ultraviolet light exposure for 5 h, and concentration of VA-044 of 0.2%. CTS-g-PDMDAAC demonstrated superior performance overall to CTS according to various characterization methods, such as FTIR, XPS, XRD, and BET. The coagulation experiment showed that at a dosage of 6.0 mg/L, the removal rates of residual turbidity and chlorophyll a reach 0.58 NTU and 99.37%, respectively, and the generated flocs have a dense structure and exhibit strong shear resistance. Finally, the flocculation mechanism was explored. Compared with traditional flocculants, CTS-g-PDMDAAC has the advantages of efficient algae removal, lower sludge production, no secondary pollution, and potential for the utilization of microalgae. This research provides theoretical support and suggests technical pathways for the development of biobased, environmentally friendly flocculants with broad pH adaptability.