A composite of chitosan and covalent organic framework, modified with choline chloride/urea deep eutectic solvent, as...

In this study, urea/choline chloride deep eutectic solvent-modified chitosan-covalent organic framework composite (DES/CS-COF) was synthesized. The DES/CS-COF was used for the first time for the effective removal of chlorpyrifos (CPF) pesticide from an aqueous solution. To cross-link CS, sulfuric acid was employed as an available, non-toxic, and green cross-linking agent. DES was applied as a green, low-cost, and low-toxic modifier to increase the interactions of DES/CS-COF with CPF. The use of DES to modify the CS-COF composite was innovative and addressed the need for an effective and environmentally friendly adsorbent. The synthesized DES/CS-COF composite can address some main drawbacks of CS in terms of low stability, specific surface area, and adsorption capacity. In addition, the DES/CS-COF provides multi-interaction sites, such as electrostatic interaction, hydrogen bonding, and π-π stacking with CPF. The maximum adsorption capacity of the DES/CS-COF composite was 114 mg g^-1, which is more than that of some other adsorbents used for the removal of CPF. Moreover, a low dosage of the DES/CS-COF composite (0.026 g) was enough to remove CPF in a short time (7 min).