Efficient degradation of 4-nitrophenol using VO(TPP) impregnated TiO2 photocatalyst: Insight into kinetics and mechanism

Abstract

AbstractHeterogeneous composites of metalloporphyrins with TiO2 possess exceptional photosensitizing properties, which works efficiently in degradation of organic pollutants. Herein, vanadium porphyrin complex {VO(TPP)} was loaded on TiO2 photocatalyst {VO(TPP)–TiO2} by the wet impregnation method. The as-prepared catalysts were characterized to analyze physicochemical properties and the photocatalytic degradation of 4-nitrophenol (4-NP) was investigated to assess their catalytic efficiency. XRD results revealed that VO(TPP)–TiO2 is dual-phase anatase/rutile with high crystallinity. The UV-DRS study showed that the loading of {VO(TPP)} on TiO2 caused a red-shift in the absorption spectrum and decreased the band-gap as well. The surface area has increased significantly after impregnation as confirmed by BET isotherm. The degradation of 4-NP follows pseudo-first-order kinetics, and the VO(TPP)–TiO2 showed higher degradation (99%) of 4-NP as compared to pure TiO2 (87%). The degradation mechanism of 4-NP and its pathway was also discussed using UV–Vis spectroscopy and electrospray mass spectrometry analysis. Graphical abstract