Photodegradation of pentachlorophenol and its degradation pathways predicted using density functional theory

• Published in: Chemosphere (Oxford) Vol. 61; no. 3; pp. 341 - 346
• Main Authors: Suegara, Junya, Lee, Byung-Dae, Espino, Maria P., Nakai, Satoshi, Hosomi, Masaaki
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.10.2005; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Applied sciences; Biological and medical sciences; Biological and physicochemical phenomena; chemical structure; chlorides; Chlorine balance; dechlorination; Dechlorination pathway; Density functional theory; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Forecasting; Fundamental and applied biological sciences. Psychology; Gaussian; General purification processes; Insecticides - chemistry; mineralization; Models, Chemical; Natural water pollution; organochlorine compounds; Pentachlorophenol; Pentachlorophenol - chemistry; Photochemistry; photolysis; Pollution; Pollution, environment geology; Soil and water pollution; Soil science; ultraviolet radiation; Wastewaters; Water Purification; Water treatment and pollution; Dechlorination pathway; Density functional theory; Gaussian; Pentachlorophenol; Chlorine balance; Reaction intermediate; Agricultural chemical product; Quantum chemistry; Pollution control; Persistent organic pollutant; Dechlorination; Chlorine Organic compounds; Reaction mechanism; Waste water discharge; Organic compounds; Photochemical degradation; Pollution prevention; Endocrine disruptor; Ultraviolet radiation; Density functional method; Phenols; Physicochemical purification; Water pollution; Waste water purification; Degradation product
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2005.02.090

The objectives of the present research were (i) to report the mass balance of chlorine during pentachlorophenol (PCP) photodegradation and (ii) to reveal the photodegradation pathway experimentally with a theoretical proof based on the density functional theory (DFT). The chlorine of PCP was completely mineralized to produce chloride ions after 24 h of UV irradiation. As intermediates, 2,3,5,6-tetrachlorophenol, 2,3,4,6-tetrachlorophenol and 2,5-dichlorophenol were identified. At least 80% of the chlorine balance during PCP photodegradation was accounted by PCP, these intermediates, and chloride ions. A DFT calculation showed differences in the C–Cl bond dissociation energy level and the positions of respective PCP molecular and the PCP intermediates. The dechlorination intermediates predicted using the calculated C–Cl bond dissociation energy were consistent with those experimentally confirmed, indicating the feasibility of this theoretical method in predicting the dechlorination pathway.