[Influence of cyclodextrins on the photodegradation of bisphenol A induced by Fe(III)]

Cyclodextrins (CDs) can form a host/guest inclusion complex with bisphenol A(BPA). Under a 250 W metal halide lamp (lambda > or = 365 nm), the effects of different cyclodextrins to oxidation of endocrine disrupter BPA in the Fe(III)-hydroxyl complexes system were investigated. In the presence of alpha- cyclodextrin or beta-cyclodextrin (alpha-CD or beta-CD), the photodegradation efficiency of BPA can be enhanced, but gamma-cyclodextrin (gamma-CD) showed inhibitive effect on the photodegradation efficiency. The initial degradation rate of BPA firstly increased with increasing concentration of beta-CD and alpha-CD from 0 to 60 micromol L(-1), and the maximum rate was reached at the beta-CD concentration of 60 micromol L(-1), and then decreased. But the initial degradation rate of BPA decreased with increasing concentration of gamma-CD. Furthermore, the structures of BPA, CDs and BPA/CDs were optimized used the PM3 method in Gaussian98 software package. The results showed that BPA partly entered the cavity of CDs, which formed different super-molecular host-guest complexes, and resulted in the different photodegradation rates of BPA under UV-vis irradiation.