The key role of free radicals generated from activation of H2O2, S2O82− and ozone over chromium/cerium co-doped magnetite nanoparticles

Abstract A wide range of heterogeneous catalysts has been used for degradation of dyes through various techniques, albeit, little is recognized about the productive activation of hydrogen peroxide (HP), persulfate (PS), and ozone over heterogeneous catalysts and under UV light irradiation. In this research, Cr and Ce were placed within the magnetite structure and the resultant nanoparticles were characterized by XRD, SEM, HRTEM, EDX, BET, VSM, DRS, XPS, and FT-IR analyses. The synthesized magnetic nanoparticles were used in a series of photocatalytic processes for the degradation of methylene blue dye (MBD) as a probe molecule. The Fe2.5Cr0.2Ce0.3O4 sample showed great performance in comparison with the other samples. The highest activity of Fe2.5Cr0.2Ce0.3O4 sample was described based on its ability to effectively actuate HP, PS, and ozone under UV light irradiation. The outcomes of the studied systems: catalyst, UV, and UV-catalyst alone and along with oxidants were well illustrated in contrast to one another. In this regard, the effects of HP and PS concentrations and ozone inlet flow rate were evaluated. The results postulated that the ozone-based systems had eminent efficiency in the degradation of MBD. In each process, the reusability of the Fe2.5Cr0.2Ce0.3O4 sample was studied and the superior stability of the catalyst was inferred. The mineralization efficacy of MBD was appraised by total organic carbon (TOC) and the order of TOC removal capacity was found as UV-catalyst-PS > UV-catalyst-ozone > UV-catalyst-HP. Eventually, GC–MS analysis of the oxidized samples confirmed the formation of 8 intermediates by the UV-catalyst-ozone system.