In-situ dispersing ultrafine Fe2O3 nanoparticles in mesoporous silicas for efficient peroxymonosulfate-activated degradation of tetracycline over a broad pH range

Abstract

The supported ultra-small Fe2O3 nanoparticles, as conventional functional materials for versatile applications, are scarcely investigated for their catalytic properties in peroxymonosulfate-activated reactions to deal with the ever-growing environment issues. In this work, highly dispersed ultrafine Fe2O3 nanoparticles are successfully generated in framework of mesoporous silicas (such as Fe/Si-3, with 3.01 wt% of Fe content) through an in-situ approach with iron phthalocyanine as Fe source. The formation of Fe-N or Fe-C bonds exerted remarkable isolation effect on the generation of the nanoparticles. Fe/Si-3 gave superior activity to other Fe catalysts analogs including bulk Fe2O3 in peroxymonosulfate-triggered degradation of tetracycline. Fe/Si-3 has a wide working pH window of 3–11. It can be recycled for 3 times without significant loss of the degradation activity. The radicals of SO4⋅−, ⋅OH, O2⋅− and 1O2 all contributed to the degradation reaction. The factors for high degradation efficiency and broad working pH range of Fe/Si-3, the mechanism for formation of various radicals, as well as the transformation pathway of tetracycline molecules were proposed.