A comparative study of iron-based PAN fibrous catalysts for peroxymonosulfate activation in decomposing organic contaminants

Abstract

A systematic and comparative investigation of a series of iron-based polyacrylonitrile (PAN) fibrous catalysts, synthesized by supporting Fe(III), Cu(II)/Fe(III), iron(II) 2,2′-bipyridine (FePy) and iron(II) phthalocyanine (FePc) onto amidoximated PAN fiber respectively, for peroxymonosulfate (PMS) activation towards the oxidative degradation of organic contaminations was conducted. We found that there are significant differences in the catalytic activity of iron with various chemical environments. Taking the oxidation of reactive red 195 as model reaction, the FePc supported fibrous catalyst achieved the highest catalytic activity, which mainly originated from the enhanced regeneration of Fe(II) from Fe(III) by the electron-rich characteristic of FePc, as well as the rapid PMS adsorption through abundant axial coordinate sites of FePc. In addition, visible light could significantly accelerate the dye degradation by PMS activation over these catalysts, with the catalytic activities shown in order as follows: FePc > FePy > Cu(II)/Fe(III) > Fe(III). ESR and designed experiments revealed that sulfate and hydroxyl radicals were produced during PMS activation over these catalysts, and high-valent iron-oxo species was also involved in the FePc supported PAN fibrous catalytic system. Furthermore, the excellent pH tolerance and recycling capability, as well as the high activity for dye mineralization enabled FePc supported PAN fibrous catalyst to hold great promise for environmental remediation via PMS activation. Our findings provide further insight into the catalytic mechanism of PMS activation over iron-based catalyst and also allow the design of more efficiency iron-mediated PMS-based advanced oxidation process.