Heterogeneous activation of peroxymonosulfate by different ferromanganese oxides for tetracycline degradation: Structure dependence and catalytic mechanism

Abstract

In this work, ferromanganese oxides (FMOs) synthesized with different Fe and Mn ratio using sol–gel method showed good activity in the activation of peroxymonosulfate (PMS) for tetracycline degradation. The structure and surface characterizations of the FMOs were measured using XRD, BET and XPS. The variation of the catalytic performance of FMOs in the degradation of TC was investigated with varied initial conditions. The FMO-46 structured as FeMnO3 with cubic structure could activate PMS efficiently due to the large surface area and surface Mn(III) sites. While the high catalytic activity of FMO-73 was attributed to the high percentage content of surface Fe(II) and Mn(II). The more vicinities of Fe and Mn exist on the surface of FMOs result in a better catalytic activity towards PMS and degradation of TC. The catalytic mechanism was elucidated by detecting the reactive oxidation species generated using ESR measurement and radical scavengers. It was found that Mn-oxides with Fe-regulated-surface active sites were expected to enhance the catalytic activity in the generation of SO4−. The experimental results demonstrated that SO4− had a higher contribution to degrade tetracycline in PMS/FMO system than OH. This study proves that surface regulated FMOs can efficiently activate PMS to degrade refractory organic pollutants as an environmentally friendly catalyst.