Efficient and Cost‐Effective Anionic Flocculants Synthesized by Grafting Carboxymethyl Cellulose and Sodium Alginate With Acrylamide

Dye wastewater presents a growing threat to both the natural environment and human health, necessitating the development of efficient, cost‐effective, and eco‐friendly flocculants for its treatment. In response to this challenge, this study successfully prepared a carboxymethyl cellulose‐acrylamide‐sodium alginate (CAS) anionic terpolymer via a microwave‐assisted copolymerization method. Through the flocculation performance towards a simulated dye wastewater containing 100 mg/L of the cationic dye crystal violet, the optimal synthesis process was determined. Results indicated that the optimal CAS concentration of 30 mg/L achieved a removal rate of up to 93.7% for the dye solution of 100 mg/L. The flocculation mechanism of the CAS polymer is primarily based on charge neutralization, with additional effects from bridging and net trapping. This mechanism allows for excellent flocculation performance across wide ranges of dye concentration, pH, and ambient temperature. Furthermore, the cost of CAS is nearly equivalent to that of commercially available polyacrylamide, yet it offers a significant reduction in operating costs, accounting for only one‐fifth of the cost required for polyacrylamide to remove the same amount of dye. The prepared CAS copolymer offers the advantages of abundant sourcing, low cost, eco‐friendliness, and high performance, making it a highly competitive candidate for practical wastewater treatment.