Enhanced removal of antibiotics and turbidity from water using CS-CMC complex coacervate flocculant: Mechanisms and performance

The widespread use of antibiotics has exacerbated water pollution, especially as traditional flocculation methods struggle to effectively remove persistent dissolved pollutants. Traditional coagulants often fall short of high-quality water standards due to residual toxicity and degradation issues. In contrast, natural polysaccharide-based polymeric flocculants show great promise. This study developed an efficient composite coagulation system using the complex coacervation method, enabling in situ self-assembly of chitosan (CS) and sodium carboxymethyl cellulose (CMC) in aqueous solution. The formation conditions were optimized via conductivity and Zeta potential analyses. FTIR, XPS, and SEM were used to probe the composite's microscopic structure and mechanism. Results showed the CS-CMC system outperformed chitosan alone, achieving a 99.70 % turbidity removal rate in simulated Yellow River water. It also efficiently removed various pollutants, with 87.60 % norfloxacin (NOR) and 50.12 % tetracycline (TC) removal rates. The adsorption kinetics of NOR and TC followed pseudo-second-order and intraparticle diffusion models, indicating unique interaction mechanisms beyond simple adsorption, with TC adhering to the Langmuir model and Temkin model, NOR to the Freundlich model. This eco-friendly flocculant offers an efficient, multifunctional solution for green water treatment.