Decomposition of 2-chlorophenol in aqueous solution by UV irradiation with the presence of titanium dioxide

The decomposition of 2-chlorophenol in aqueous solution by UV/TiO2 oxidation process was studied under various solution pH values, light intensities and types of TiO2. The removal of 2-chlorophenol and organic intermediates was found to be more effective for acidic solutions. The decomposition of 2-chlorophenol can be fitted well by a pseudo first-order kinetics. Experimental results indicated that the distribution of non-chlorinated and chlorinated intermediates on the photocatalytic decomposition rate of 2-chlorophenol were highly dependent on solution pH. At the same light intensity, the adequate dosage of TiO2 was found to be less for alkaline solutions than that for acidic solutions. Increasing the light intensity would significantly increase the decomposition rate of 2-chlorophenol at pH 3, but not at pH 11. Both rutile and anatase forms of TiO2 were used in this study. The destruction rate of 2-chlorophenol of unit weight of rutile was less than that of anatase. However, the decomposition rates of 2-chlorophenol of unit surface area for both were almost the same in this research. Thus, the difference of the decomposition rates of 2-chlorophenol might be attributed to the difference of the surface area of various forms of TiO2, not to the difference of the crystal properties. Copyright (C) 1996 Elsevier Science Ltd