Adsorption and Photodecomposition of Diphenolic Acid in /spl alpha/- or /spl beta/- Cyclodextrins and TiO/sub 2/ Suspensions

The adsorption and photodecomposition of diphenolic acid (DPA) was investigated in the presence of αor cyclodextrins (CDs) and TiO2 suspensions. The adsorption of DPA on TiO2 surface and inclusion complex of CDs and DPA were critical factor in the photocatalytic reaction. Results showed that, the adsorption isotherms of DPA could be plotted with the Langmuir isotherm model, and the maximum adsorption capacity increased in the order of α-CD/TiO2 TiO2> -CD/ TiO2). The influence factors of -CD concentration, DPA initial concentration on photodegradation of DPA were studied. This paper also simply explored the mechanism of the different degradation effect in the presence of or -CD. With the addition of -cyclodextrin, the enhancement of photodegradation of DPA mainly results from the enhancement of adsorption of DPA on TiO2 surface and the lower bond energy between some atoms in DPA molecule after inclusion interactions with -CD. While with the addition of -CD, the photodecomposition inhibition role of -CD to DPA on TiO2 surface leaded to reducing photodegradation of DPA, because CD and DPA did not form a stable inclusion compounds and decreased the adsorption amount of DPA on the TiO2 surface. Keywords-TiO2 ;diphenolic acid ; cyclodextrin; photodecomposition ; adsorption