Abstract

The influence of surface pH of activated carbon on selectivity of TiO2 during the photooxidation of 4-chlorophenol on UV-irradiation was studied. Chlorine substitution by p-hydroxylation yielding hydroquinone in equilibrium with benzoquinone and o-hydroxylation to 4-chlorocathecol were detected as the main intermediates in the photooxidation of 4CP. Changes in surface pH of carbons from basic to closely neutral induce a remarkably increase in the production of 4-chlorocatechol by a factor of 22 on TiO2-AC in comparison of TiO2 alone. A mechanism of interaction between both solids is proposed to explain changes both in photoactivity and photoselectivity of TiO2. In conclusion, results showed that TiO2-AC can be used as an alternative green photocatalyst in organic synthesis.