Photocatalytic Degradation of Diphenolic Acid in the Presence of Beta-Cyclodextrin under UV Light

This paper investigated the photocatalysis degradation of diphenolic acid (DPA) in the presence of beta-cyclodextrin (beta-CD) under a 30 W UV lamp ( lambda_max=254 nm ). In control experiment, the photodegradation rate of DPA is enhanced 33.5% after 30 min irradiation. The interaction of DPA with beta-CD yielded the formation of inclusion complexes at 1:1 stoichiometric ratio in solution, and beta-CD can form steady host/guest inclusion complex with DPA. The photodegradation of 10-100 mumol/L DPA irradiated UV lamp in aqueous solution was found to follow the pseudo-first-order law. Obviously, the photocatalytic degradation reaction rate constant of DPA in the system containing beta-CD is higher than that without beta-CD, and the first-order rate constant increased by 9.18-fold in the presence of beta-CD. With the addition of beta-cyclodextrin, the enhancement of photodegradation of DPA mainly results from moderate inclusion depth of DPA molecule in the beta-CD cavity. This kind of inclusion structure allows DPA molecule sufficient proximity to secondary hydroxyl groups of the beta-CD cavity, and these hydroxyl groups could be activated and converted to hydroxyl radicals under UV irradiation, which can enhance the photooxidation of DPA. This could be a promising method for Endocrine disrupting compounds in water remediation.