Covalent organic polymer/chitosan multifunctional granular aerogels for diclofenac sodium removal from water

The adsorptive removal of pharmaceutical contaminants, such as diclofenac sodium (DFS), from water is of high environmental importance because of their adverse biological effects. Covalent organic polymers (COPs) show good DFS removal performance but are poorly suited for industrial applications because of their powder form. Herein, we synthesized an amine- and carboxyl group-rich aromatic COP (CCP-NH2) with a large surface area (1227 m2/g) and used it to prepare a series of granular CCP-NH2/chitosan aerogels (CCN-AG-x, where x = 0–90 wt% is the loading of CCP-NH2). The best-performing sample, CCN-AG-80, exhibited a high surface area and mechanical strength, low density, excellent stability in various solvents, and facile processability into different shapes. Moreover, CCN-AG-80 exhibited a high DFS adsorption capacity (501 mg/g), fast adsorption kinetics (<30 min), negligible interference from competing species, and good adsorption/desorption cycling behavior. The superior mechanical strength and excellent DFS removal performance of CCN-AG-80 were attributed to the synergistic effects of chitosan and CCP-NH2. Moreover, CCN-AG-80 showed promising potential for the removal of various pharmaceutical contaminants from water. Synthesizing granular aerogels from the combination of chitosan and COP with large surface area and diverse heteroatoms would be an efficient strategy to develop adsorbents for the removal of pollutants from water media.