Natural mineral-derived CuFe2S3 for synergistic photo-Fenton degradation of tetracycline with ultralow metal leaching and high stability

Mineral-derived CuFe 2 S 3 was produced by one-step N₂ calcination. • Low-valence sulfur promotes Fe/Cu cycling and charge separation. • 91.25% TC removal was achieved with Fe < 0.1 and Cu < 1.5 mg/L. • Activity remained 76.32% after five cycles in complex water. • TC products evolved toward low-toxicity, non-mutagenic species. Natural mineral-based heterogeneous Fenton catalysts are promising for water remediation but are often limited by metal leaching and poor stability. Here, natural copper sulfide concentrate was converted into phase-pure CuFe 2 S 3 by one-step calcination under N₂ at 750 °C. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) confirmed the formation of highly crystalline CuFe 2 S 3 with a 0.305 nm lattice fringe assigned to the (111) plane. X-ray photoelectron spectroscopy (XPS) revealed abundant Fe 2+ (50.69 %), Cu + (78.61 %), and low-valence sulfur species, while ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy gave a band gap of 1.51 eV. These features establish a photo-responsive Fe-Cu-S electron-transfer network in which low-valence sulfur promotes Fe 3+ /Fe 2+ and Cu 2+ /Cu + cycling and suppresses charge recombination. Under optimized conditions (0.50 g/L catalyst, 40 mmol/L H 2 O 2 , unadjusted pH), the CuFe 2 S 3 /H 2 O 2 /light system achieved 91.25 % tetracycline removal within 120 min, with Fe and Cu leaching below 0.1 and 1.5 mg/L, respectively. The removal efficiency remained 86.47 % after five cycles, and the catalyst also showed broad-spectrum activity and good tolerance to complex water matrices. Scavenging experiments identified ·OH and h + as the dominant reactive species, while electron spin resonance confirmed the formation of ·OH, ·O 2 - , h + and 1 O 2 . Liquid chromatography–mass spectrometry (LC–MS) and quantitative structure–activity relationship (QSAR)-based toxicity prediction indicated progressive N-demethylation, ring opening, and fragmentation of tetracycline, accompanied by reduced predicted acute toxicity and mutagenicity. This work demonstrates that controlled phase reconstruction can simultaneously enhance catalytic activity, structural stability, and environmental safety in natural mineral-derived catalysts. Download: Download high-res image (295KB) Download: Download full-size image