Guanidine-Functionalized Covalent Organic Framework for Efficient Adsorption of Diclofenac Sodium: Synthesis, Performance, and Mechanism

• • COF-TFPPy-DGCl achieves a maximum adsorption capacity of 370 mg·g−1 for diclofenac sodium, outperforming many conventional adsorbents and enabling high-load treatment in industrial wastewater applications. • • The adsorbent exhibits exceptional selectivity, with a DCF removal rate of 96.75% versus <20% for ciprofloxacin and bisphenol A, allowing targeted removal of DCF from complex pharmaceutical mixtures. • • Adsorption kinetics follow a pseudo-second-order model, reaching equilibrium within 30 minutes, which facilitates rapid treatment cycles and reduces operational residence time in continuous-flow systems. • • The material maintains 80% of its adsorption capacity after five regeneration cycles, demonstrating cost-effective reusability and operational stability for long-term water purification.