Solar light-induced degradation of bisphenol-A with TiO2 immobilized on Ti

The photocatalytic degradation of bisphenol-A (BPA) was investigated over immobilized TiO2/Ti-film catalysts irradiated by artificial solar light. Catalysts were prepared either by a sol–gel method (TIP catalyst) or deposition of Degussa P-25 slurry (P-25 catalyst) and characterized by X-ray diffraction. The effect of TiO2 loading (0.65 and 1.3 mg), initial BPA concentration (150, 300 and 600 ppb) and initial solution pH (3, 6, 8 and 10) on degradation was studied. The latter was assessed following changes in BPA concentration by means of high performance liquid chromatography equipped with a fluorescence detector. It was found that both catalysts, consisting of about 75:25 anatase:rutile, were equally active in degrading BPA (e.g. 85% reduction at 300 ppb BPA concentration, 180 min of reaction, 0.65 mg catalyst loading and inherent pH) and conversion increase with increasing the TiO2 loading; however, the P-25 catalyst was considerably unstable at high loadings suffering about 50% active phase dissolution. Conversion decreased with increasing BPA concentration and it was favored in the pH range 6–8. BPA degradation can be approached by a pseudo-first order rate expression with the apparent kinetic constant taking values between 6 × 10−3 and 2 × 10−2 s−1.