Enhanced TiO2 photocatalytic degradation of bisphenol A by β-cyclodextrin in suspended solutions

Enhancement of β-cyclodextrin (β-CD) on TiO2 photocatalytic degradation of bisphenol A (BPA) was investigated under a 250 W metal halide lamp (λ ≥ 365 nm) in this work. In the system of photocatalytic degradation of BPA, the photodegradation rate of BPA in aqueous solutions containing β-CD and TiO2 was obviously faster than that in aqueous solutions containing only TiO2. After 60 min of irradiation, β-CD could increase the photodegradation efficiency by about 23% for 10 mg l−1 BPA in the UV–vis/TiO2 system, the photodegradation of 2.5–20.0 mg l−1 BPA in aqueous solutions was found to follow pseudo-first-order law, and the adsorption constant and the reaction rate constant of BPA in the system containing β-CD and TiO2 are obviously higher than those in the system containing only TiO2, the influence factors on photodegradation of BPA were studied and described in details, such as β-CD concentration, pH, BPA initial concentration and gas medium. The formation of CO2 as a result of mineralization of BPA was observed during the photodegradation process. After 120 min of irradiation, the mineralization efficiency of BPA reached 100% in the presence of β-CD, whereas mineralization efficiency was only 36.7% in the absence of β-CD. The enhancement of photodegradation of BPA mainly results from the enhancement of adsorption of BPA on TiO2 surface and the lower bond energy between some atoms in BPA molecule after inclusion interactions with β-CD.