Enhanced photocatalytic degradation of tetrabromobisphenol A by tourmaline-TiO2 composite catalyst

The TiO2 supported on tourmaline composite catalyst was successfully prepared by a sol-gel method and was characterized by scanning electron microscopy, X-ray diffraction and nitrogen adsorption-desorption analysis. The results showed that the addition of tourmaline increased crystallite sizes of TiO2. Furthermore, the photocatalytic activity of the tourmaline-TiO2 composites obtained was evaluated by the degradation of tetrabromobisphenol A (TBBPA). Compared with bare TiO2, the tourmaline-TiO2 composites exhibited the excellent photocatalytic activity for the degradation of TBBPA and this degradation enhanced was correlated with the tourmaline dosages and the optimum photocatalyst is found to be T(20%)-TiO2 catalyst. It implied that the higher dosage of tourmaline facilitated migration of charge carriers and higher photon-to-electron conversion efficiency. The photocatalytic reaction followed pseudo-first-order kinetics and the Langmuir-Hinshelwood model. The photodegradation efficiency of TBBPA enhanced with the increase in pH value. Additionally, metal ions influenced the photocatalytic degradation of TBBPA by T(20%)-TiO2 catalyst, Cu2+ could accelerate TBBPA degradation, whereas inhibited by Mn2+ and Fe3+. Importantly, five intermediate products of TBBPA at m/z 463, 355, 293, 255 and 137 were observed by HPLC-MS/MS. The possible photodegradation pathway of TBBPA by tourmaline-TiO2 composite catalyst was proposed. Generally, the incorporation of mineral with spontaneous permanent poles to TiO2 with photocatalytic activity offers a promising technology to the practical application of TiO2 in contamination control.