The prevalence of pharmaceuticals and other organic micropollutants in surface and groundwater poses a serious environmental consequence. Here, metal–organic framework (MOF)–derived iron nitrides (FeN) carbon composites were designed as an efficient photochemical oxidation catalyst to degrade diclofenac (DCF) via persulfate (PS) activation. The carbon-supported FeN materials (FeN(w%)@C_x, with w and x representing the weight percentage and the pyrolysis temperature, respectively) were obtained by preparing iron-doped MOF precursors and subsequently subjecting them to high-temperature pyrolysis. The prepared FeN(w%)@C_xs were applied to remove DCF from aqueous media after thorough characterization. The FeN(w%)@C_xs efficiently activated PS under light condition (intensity 950 W m^-2), enabling rapid DCF degradation with high turnover frequencies. DCF removal efficiency reached nearly ~93% in 40 min using FeN(10%)@C₉₅₀/PS system under optimized parameters such as catalyst (0.05 g L^-1), PS dose (1 mM), and initial DCF concentration (10 mg L^-1), etc. The Fe–N–C structure of FeN(10%)@C₉₅₀ enables the light–driven activation process involving radical species (SO₄^•- and ^•OH), as well as non-radical reactive oxygen species (¹O₂), proceeding via an electron-transfer mechanism, as confirmed by scavenger tests, ESR spectroscopy, and electrochemistry. DCF degradation rate was influenced with the addition of different anions, cations, and organic acids in FeN(10%)C₉₅₀/PS system under light. The optimum pH (5-9) showed higher degradation rate. Additionally, the reusability and stability of the FeN(10%)@C₉₅₀ were confirmed over multiple cycles and DCF degradation products using LC-MS. Finally, the obtained results emphasize the potential of these catalysts in wastewater remediation.

Iron Nitride Composites, Persulfate, Pharmaceuticals, Photochemical Oxidation, Wastewater Treatment