The widespread use of antibiotics in aquatic environments poses significant ecological and public health risks due to their long-term presence, harmful effects, and their role in the evolution of antibiotic resistance. Nickel ferrite (NiFe₂O₄) nanoparticles were synthesized and used as heterogeneous catalysts in a UV-assisted photo-Fenton method to degrade sulfamethoxazole (SFX) and metronidazole (MTZ) from aqueous solutions. XRD, SEM-EDS, and FTIR investigations showed the presence of a crystalline spinel phase having an average crystallite size of 19.91 nm, a porous surface shape, and a homogenous distribution of Ni, Fe, and O. Degradation studies were conducted with antibiotic concentrations ranging from 10-50 ppm under varied Fe²⁺ (0.02-0.04 mM), H 2 O 2 (0.1-0.2 mM), catalyst dosages (0.002-0.006 g/L), and pH (3-5). Under optimal circumstances of pH 3-4, 0.004-0.006 g/L catalyst, and higher oxidant doses, both antibiotics were consistently degraded by more than 90% within 120 minutes. At 10 ppm, SFX and MTZ were degraded by 94.2% and 93.2%, respectively. The degradation followed apparent pseudo-first-order kinetics with observed rate constants (k obs ) of 2.4 × 10⁻² min⁻¹ for SFX and 2.2 × 10⁻² min⁻¹ for MTZ. This behavior is consistent with the Langmuir-Hinshelwood model, which simplifies to pseudo-first-order kinetics at low pollutant concentrations in heterogeneous photocatalytic systems. The calculated Electrical Energy per Order (EE/O) was approximately 4.0 × 10³ kWh/m³/order for SFX and 4.27 × 10³ kWh/m³/order for MTZ under optimized conditions. Mechanistic analysis suggested that hydroxyl radicals (•OH) are the dominant reactive species, generated through Fe²⁺/Fe³⁺ redox cycling and UV-assisted catalytic processes. The NiFe 2 O 4 -supported photo-Fenton system significantly outperformed the traditional and advanced oxidation processes at low catalyst loadings, demonstrating the potential of NiFe 2 O 4 nanoparticles as a sustainable and scalable approach for antibiotic degradation in wastewater.
Islam et al. (Mon,) studied this question.