Chlorophene degradation by combined ultraviolet irradiation and ozonation

Abstract

Ozonation combined with UV irradiation (UV/O₃) is an advanced oxidation technique that is very promising for the destruction of organic compounds in aqueous solution. In this study, chlorophene was chosen as a model substrate to investigate the effects of pH, initial substrate concentration, ozone dose, and UV light intensity in degradation experiments. The pseudo–first-order rate constant for total organic carbon (TOC) removal was 2.4 × 10⁻², 9.8 × 10⁻⁴, and 6.4 × 10⁻² min⁻¹ for O₃, UV, and UV/O₃ treatment, respectively. Clearly, UV-enhanced ozonation leads to a synergetic increase in the overall degradation efficiency. Comparative experiments were performed to investigate the effect of the matrix (distilled water or sewage) on chlorophene removal. The organic compounds in sewage retarded the rate of chlorophene removal by 38%, probably by competitively reacting with the oxidizing agent and screening light. The compound 2-benzoylbenzo-1,4-quinone, benzo-1,4-quinone, hydroquinone and maleic acid were identified as primary intermediates by gas chromatography-mass spectrometry. The concentrations of acetic, formic and oxalic anions were detected by ion chromatography. A possible degradation pathway is proposed on the basis of the reaction products identified.

Keywords:

• Ultraviolet irradiation
• ozonation
• degradation
• chlorophene

Acknowledgments

This work was supported by the National Basic Research Program of China (Grant Nos. 20977086 and 21076196), National Nature Science Foundation of China (Grant Nos. 20977086 and 21076196), and Zhejiang Provincial Natural Science Foundation of China (Grant Nos. Z5080207 and Y5100310).