Organophosphorus pesticides (chlorfenvinphos, phosmet and fenamiphos) photoelectrodegradation by using WO3 nanostructures as photoanode

Abstract

[EN] The photoelectrocatalytic (PEC) degradation of recalcitrant and toxic organophosphorus pesticides, fenamiphos, chlorfenvinphos and phosmet, has been performed by using an innovative WO3 nanostructure as photoanode. The nanostructure has been synthesized by anodization in acidic media in the presence of a very small amount (0.05 M) of H2O2, and its composition as well as its photoelectrochemical properties have been characterized using X-ray Photoelectron Spectroscopy and X-ray diffraction as composition technique and photoelectrochemical impedance spectroscopy as photoelectrochemical analysis. After 24 h of experiment, a degradation of 95% of chlorfenvinphos, 99.9% of phosmet and 100% of fenamiphos has been achieved following pseudo-first order kinetics, indicating the good PEC efficiency of this WO3 nanostructure. Moreover, different intermediates have been identified by means of Ultra-High Performance Liquid Chromatograph coupled to a Time of Flight and Mass Spectrometer (UHPLC-Q-TOF/MS) for each of the pesticides after 24 h of photoelectrocatalytic degradation. With these identified compounds, a degradation route has been proposed for each of the pesticides in which they are decomposed into other smaller and less toxic molecules.