Construction of hierarchically porous α-Fe2O3 nanosheets from Fe-PVP hybrid gel for sustainable Fenton-like degradation of tetracycline antibiotics with low H2O2 consumption.

Emerging antibiotic pollutants pose long-term risks to ecosystems and human health, necessitating the development of advanced elimination technologies. In this study, hierarchically porous α-Fe2O3 nanosheets (α-Fe2O3-PNS) were prepared from an iron-polyvinylpyrrolidone (Fe-PVP) hybrid gel, where PVP served multiple functions, including iron immobilization, morphology template, pore formation, and crystallite growth regulation. As an efficient heterogeneous Fenton-like catalyst, α-Fe2O3-PNS achieved 93.6 % degradation of tetracycline (TC, 25 mg/L) within 2 h under mild conditions (25 °C, pH 5) using only 4 mM H2O2. The reaction followed pseudo-first-order kinetics with a high rate constant (0.0606 min-1) and an outstanding normalization factor (8.13). Key operational parameters (i.e., PVP dosage, catalyst loading, H2O2 concentration, initial pH, coexisting anions and natural organic matter) were investigated. The material exhibited good reusability over five consecutive cycles and maintained robust performance in real water matrices. Its superior catalytic activity originated from exposed (113) crystal planes, abundant accessible iron sites, and rapid Fe3+/Fe2+ redox cycling facilitated by the large surface area. Radical quenching tests and electron paramagnetic resonance spectroscopy confirmed that hydroxyl radicals, generated via surface Fe2+-mediated H2O2 activation, are dominant reactive species, driving TC degradation through hydroxylation, oxidative cleavage, and ring-opening reactions. This study provides an energy- and resource-efficient solution for sustainable water remediation, operating effectively under ambient and circumneutral conditions with low H2O2 consumption.