Optimization of degradation kinetics towards O-CP in H3PW12O40/TiO2 photoelectrocatalytic system

Abstract

Kinetics is crucial for photoelectrocatalytic degradation of organic contaminants. A 12-tungstophosphoric acid/titania (H3PW12O40/TiO2) composite film was prepared by the sol-gel-hydrothermal route to investigate the optimal conditions and degradation kinetics of o-chlorophenol (o-CP). The photoelectrocatalytic degradation efficiency of o-CP was 96.6% after 180 min under optimum conditions (impressed voltage: 0.5V, solution pH: 6.3, and initial concentration: 5mg·L-1), and the apparent kinetics constant (K') was a 6.0-fold increase compared to the photocatalytic system. Furthermore, the photoeletrocatalytic reaction rate of o-CP by H3PW12O40/TiO2 and TiO2 film was 0.090 and 0.020 mg·L-1·min-1, respectively, and a higher apparent quantum yield (F = 32.14%) of H3PW12O40/TiO2 composite film was attained compared to TiO2 film (Φ = 10.00%), owing to the fact that more photo-generated carriers were produced and effectively separated. Intermediate products identified during o-CP degradation by liquid chromatography-mass spectrometer (LC-MS) were 2-Chlorohydroquinone (CHQ), catechol (CT), and hydroxyl-hydroquinone (H-HQ). The H3PW12O40/TiO2 photoelectrocatalytic system exhibited outstanding potential for the removal of chlorinated organic contaminants in wastewater.