Activation of peroxymonosulfate under visible-light illumination for enhanced degradation of acetaminophen by self-assembly iron phosphorus/hexagonal tubular graphite carbon nitride

Abstract

Improving the visible light response by sulfate-based advanced oxidation processes (S-AOPs) is a promising method for the efficient degradation of organic matter in water. Herein, we facilely fabricated the iron phosphorus/hexagonal tubular graphite carbon nitride (FeP/HTCN) composites via two-phase hydrothermal supramolecular self-assembly and thermal-condensation method. FeP/HTCN with the shape of hollow hexagonal tubular loaded iron phosphorus particles was first synthesized. The results suggested that the loading of iron phosphate greatly enhanced its ability to activate peroxymonosulfate (PMS) while also improving the photocatalytic ability of the catalyst due to its smaller bandgap. The combined effect of iron phosphate, HTCN, and visible light (wavelength ≥ 420 nm) assistance facilitated the enhancement of the reaction activity. Electron paramagnetic resonance techniques (EPR) and radial quenching experiments validated that singlet oxygen (¹O<inf>2</inf>) derived from superoxide was the main active species. The degradation pathways of acetaminophen (APAP) were determined and the mechanism of mineralization and decomposition was demonstrated. This work provided a proposal for the application of iron salts represented by iron phosphate in S-AOPs.