Synergistic removal of phosphate, humic acid and antibiotics by magnetic chitosan: Performance and mechanism

With the development of society and economy, eutrophication and antibiotics have posed risks to aquatic ecosystems and human health. In this study, magnetic chitosan (MCS) was synthesized via co-precipitation for the adsorption removal of combined pollutants from wastewater. MCS achieved removal efficiencies of 92.0 ​%, 93.1 ​%, and 91.5 ​% for phosphate, norfloxacin, and humic acid, respectively. MCS exhibited a wide pH adaptability, along with easy recovery and stability. Surface morphology, elemental composition, and crystal structure of MCS before and after adsorption were characterized. Various models were employed to fit adsorption kinetics, isotherms, and thermodynamics to analyze the adsorption mechanisms. The phosphate removal was primarily driven by electrostatic interactions and complexation, while norfloxacin removal depended on indirect complexation with humic acid, leading to co-precipitation. This study offers valuable insights for the removal of various combined pollutants including conventional and emerging pollutants. • Recoverable magnetic chitosan (MCS) adsorbent was synthesized and was characterized. • MCS showed good removal efficiency on combined pollutants over a wide pH range. • Multiple adsorption mechanisms were involved in the adsorption process. • Humic acid facilitated the removal of norfloxacin by MCS.