Comparison of methods for the photochemical degradation of chlorophenols

Mono/polychlorophenols are currently used for a wide range of domestic, agricultural and industrial purposes. The improper disposal of mono/polychlorophenols in landfills and in low-temperature combustion contributes significantly to environmental contamination. Generally, chlorinated aromatic phenols are toxic to living organisms. For example, pentachlorophenol can affect sensitive organisms, even at low concentrations and lead to alterations in ecosystems. The objective of the present study is to investigate dehalogenation and destruction of halogenated phenols by using photochemical methods. The reactants and products were analyzed by gas chromatography. Dehalogenation was faster for monohalogenated phenols than poly-substituted phenols. Experimental data demonstrate that the reaction rate of dehalogenation in the presence of TiO(2) is 4-chlorophenol > 2,4,-dichlorophenol > 2,4,6-trichlorophenol. To overcome the low solubility of higher chlorinated phenols in aqueous systems, the mixture of water/methanol (60:40) was used; however, the methanolic mixture affects photodegradation rates of the chlorophenols. (C) 2002 Elsevier Science B.V. All rights reserved.