Effects of adsorbents used as supports for titanium dioxide loading on photocatalytic degradation of propyzamide

Photodecomposition in aqueous solution of 3,5-dichloro-N-(3-methyl-1-butyn-3-yl)benzamide, whose popular name is propyzamide, was investigated using naked TiO2 and TiO2-loaded adsorbent supports as photocatalysts. The adsorbent supports used were zeolite (mordenite), silica, and activated carbon. The use of adsorbent supports was found to enhance the rate of mineralization of propyzamide and to reduce the concentration of solution-phase intermediates. The experimental results suggest that the adsorbent support concentrates a target substrate of low solution-phase concentration on its surface, providing the substrate-rich environment at the adsorbent/TiO2 interface, This concentration effect results in an enhanced rate of propyzamide mineralization. The intermediates are also retained on the adsorbent support and subsequently decomposed, thereby reducing the concentration of possibly toxic intermediates in the bulk solution.