In Situ Pollutant-Functionalized Composite Aerogel for the Sequential Adsorptive Removal of Tetracycline Hydrochloride and Fe3+

Abstract Efficient treatment of the wastewater containing organic pollutants and heavy-metal ions remains a critical challenge in the environmental field. In this work, a composite aerogel has been successfully constructed using carboxymethyl chitosan (CMCs), polyethylenimine (PEI), and β-sodium glycerophosphate (β-GP) as raw materials by an in situ functionalization strategy. The sequential adsorption performance of the aerogel is systematically studied with TC as the organic pollutant and Fe3+ as the metallic ion. The results demonstrate that the aerogel exhibits excellent adsorption performance toward tetracycline hydrochloride (TC), with a maximum adsorption capacity of 299.4 mg/g. After TC adsorption, the resulting aerogel (TC@CMCs/PEI/β-GP) shows significantly enhanced capture performance for Fe3+. Following optimization via response surface methodology, the adsorption capacity for Fe3+ can reach 165.5 mg/g. Mechanistic analysis reveals that the introduction of TC can effectively reconstruct the surface coordination environment of the aerogel, and a multisite complexation system is formed, enabling efficient immobilization of Fe3+. Furthermore, the aerogel exhibits strong anti-interference capability and good reusable performance, suggesting preliminary application potential in practical wastewater treatment. This work is expected to propose a sequential adsorption strategy based on in situ functionalization by pollutant molecules, offering a new approach for a synergistically efficient removal of multiple contaminants in wastewater.