Kinetic performance of peroxymonosulfate activated by Co/Bi25FeO40: radical and non-radical mechanism

Abstract

Abstract Co/Bi25FeO40 was synthesized by a hydrothermal process and applied as a peroxymonosulfate (PMS) activator for the removal of Acid orange 7 (AO7). The morphology and physicochemical features of Co/Bi25FeO40 were obtained and analyzed via multiple characterizations. Crucial parameters including catalyst dosage, PMS concentration, temperature, pH and AO7 concentration were evaluated thoroughly for the kinetics performance. The results revealed that the efficient PMS activation performance was demonstrated using the synthesized Co/Bi25FeO40. Increasing catalyst dosage, PMS concentration, temperature and pH could promote AO7 removal, while the increase of AO7 concentration led to the inhibited degradation. Structural characterization, use of chemical probes and data of ESR analyses demonstrated that sulfate radicals and singlet oxygen (1O2) were identified as the major reactive oxygen species. Simultaneous pathways through radicals (sulfate radicals) and non-radical (singlet oxygen) were proposed with oxygen vacancy, active oxygen (O*) and the redox pair Bi5+/Bi3+ involved. This study could explore the application field of sillenite bismuth ferrite in non-photochemical application for environmental remediation.