Degradation of organic pollutants on NiFe2O4/PANI/rGO nanocomposites by peroxymonosulfate activation technology

With the increasing environmental pollution, especially water pollution, it is urgent to develop environmentally friendly, low-consumption, and efficient water treatment technology. Compared with other oxidants (H₂O₂, peroxydisulfate (PDS), etc.), peroxymonosulfate (PMS) can degrade organic pollutants efficiently and at high speed. It is important to design a catalyst suitable for advanced oxidation processes (AOPs). By a simple solvothermal method, metal catalyst NiFe₂O₄ was combined with non-metal materials polyaniline and graphene to activate PMS for rhodamine B degradation. The surface morphology and chemical composition of the catalysts were studied using SEM, EDS, XRD, Raman spectroscopy, and FR-IR. The NiFe₂O₄/PANI/rGO composite catalysts exhibited excellent catalytic activity such that 98.05% rhodamine B could be degraded in the presence of 0.20 g L⁻¹ catalyst and 1.2 mM PMS within 30 min. Combined with the results of X-ray photoelectron spectroscopy characterization of catalysts before and after the catalytic reaction, it is proposed that the possible degradation mechanism is mainly that electrons provided by carbon materials are captured by dissolved oxygen in the system to generate superoxide free radicals, and metal ions react with PMS to generate sulfate free radicals. Some of the generated sulfate radicals will also be converted into hydroxyl radicals, and the organic pollutant molecules will react with the active radicals in the system to achieve the degradation of pollutants.