Preparation of porous DAP-IPA-POPs for efficient adsorptive removal of organochlorine pesticides

There is an urgent need to develop efficient strategies to remove the plant growth regulator forchlorfenuron (CPPU), due to its persistent contamination of aquatic environments. A cost-effective imine-linked porous polymer (Pre-DAP-IPA-POPs) was synthesized through the condensation of 2,6-diaminopyridine (DAP) with isophthalaldehyde (IPA), followed by in situ reduction with KBH 4 to obtain DAP-IPA-POPs. Under optimized conditions (298 K, pH 7, 2 h, and 10 mg of adsorbent), the material achieved a CPPU adsorption capacity of 98.62 ± 8.29 mg·g −1 . Thermodynamic analysis indicated the exothermic nature of the adsorption process ( ΔH 0 =-10.37 kJ·mol −1 ), while kinetic modeling revealed that adsorption reached equilibrium within 2 h and followed a pseudo-second-order kinetic model. 13 C Solid-state NMR and infrared results indicate that the material was successfully synthesized. Furthermore, the successful adsorption of CPPU was evidenced by the emergence of characteristic Cl 2p signals in the XPS spectra of CPPU@DAP-IPA-POPs. Quantum chemical calculations revealed an electron transfer from the HOMO of the unchlorinated phenyl ring in CPPU to the LUMO of DAP-IPA-POPs, which is primarily localized on the C N groups. Noncovalent interaction (NCI) analysis revealed that hydrogen bonding and van der Waals interactions dominated the adsorption process, with steric repulsion exerting a minor opposing effect. These insights collectively demonstrate the promise of DAP-IPA-POPs as a cost-effective and efficient adsorbent for agricultural wastewater remediation.