DFT-Backed Study on the Synergistic Photodegradation of Ternary Drug-Dye Pollutants via Cd-Based MOF

The simultaneous removal and detection of mixed water pollutants-particularly synthetic dyes and antibiotics-remains a major challenge for environmental remediation technologies. Herein, a ligand-engineered cadmium-based metal-organic framework (Cd-MOF), synthesized from bis(2-carboxyethyl) isocyanurate (H₂Cei) and 1,4-bis(1H-imidazol-1-yl)methyl]benzene (Bimb) ligands, that exhibits dual functionality for visible-light-driven photocatalytic degradation and fluorescent sensing is reported. The Cd-MOF demonstrates high crystallinity, mesoporosity (BET surface area: 598 m² g^-1), and structural robustness. Under visible light, it achieves >96% degradation of Rhodamine B (RhB), Methylene Blue (MB), and ciprofloxacin (CPF) within 150 min, and maintains efficient performance in a ternary mixture, with selectivity toward RhB. Radical trapping and photophysical studies reveal a reactive oxygen species-driven degradation mechanism, while DFT calculations confirm pollutant-induced band gap modulation and enhanced charge transfer. Moreover, the Cd-MOF selectively detects CPF via fluorescence quenching with a detection limit of 0.563 ppm, showing excellent sensitivity, reusability, and pH stability. This study presents a structurally tunable and multifunctional MOF platform for integrated pollutant degradation and real-time antibiotic sensing, supported by combined experimental and theoretical validation.