Visible light assisted magnetic COF/HKUST/CoFe2O4 composite as a novel photocatalyst: green synthesis and efficient degradation of pollutants (dye and pharmaceutical) in water

This study reports the facile, green synthesis of ternary magnetic photocatalyst composites (COF/HKUST/CoFe 2 O 4 ) with tunable COF: HKUST ratios, integrating an amide-based covalent organic framework, the metal-organic framework (HKUST-1), and CoFe 2 O 4 nanoparticles. The hybrid was comprehensively characterized by FTIR, XRD, SEM, MAP and EDX, TEM, VSM, AFM, PL and DRS. The optimized COF/HKUST/CoFe 2 O 4 composite achieved 95% degradation of 90 mg/L doxycycline (DOX) within 180 min and 97% removal of 20 mg/L methylene blue (MB) in 150 min under visible-light irradiation. This efficacy stems from synergistic heterointerface interactions that promote efficient charge separation, accelerated electron transfer, and suppressed recombination. Kinetic modeling confirmed second-order degradation for DOX and first-order for MB, while scavenging assays identified photogenerated holes (h⁺) as the dominant oxidative species, followed by hydroxyl radicals and superoxide anions. Notably, the composite enables straightforward magnetic separation, and robust recyclability, retaining > 72% pollutant degradation efficiency over five consecutive cycles. This work advances sustainable wastewater remediation by providing a low-cost, scalable photocatalyst that aligns with circular economy principles and United Nations Sustainable Development Goal 6, offering a versatile platform for mitigating antibiotic resistance and dye-induced aquatic toxicity.