Efficient oxidation of ibuprofen by nano-plate Bi2Fe4O9 activated peroxymonosulfate

Abstract

Advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) have received extensive attention in the elimination of persistent organic pollutants in recent years. The activation of PMS depends on the selection and preparation of the catalyst. This study prepared nano-plate Bi2Fe4O9 using a one-step hydrothermal method to active PMS for the elimination of ibuprofen (IBP). The influence of hydrothermal reaction parameters on the activity of Bi2Fe4O9 (BFO) toward PMS was investigated to optimize the synthesis conditions. The obtained optimal BFO exhibited higher catalytic activity toward PMS in terms of IBP degradation than its homogeneous counterpart (Fe2+/PMS). IBP (0.025 mM) was completely degraded within 5 min at pH ranging from 5 to 9; the optimal pH level was neutral. Based on EPR measurements and radical quenching tests, both SO4•− and •OH contributed to IBP degradation in BFO/PMS system. Oxygen vacancies (OVs) and Fe(III) are believed as the active sites on BFO surface to activate PMS based on EPR measurements, Raman spectra and DFT calculation. The degradation pathways of IBP include decarboxylation, the oxidation of methylene, hydroxylation and demethylation in BFO/PMS system. Based on the yield of intermediates, decarboxylation was considered as a major degradation pathway.