Photocatalytic degradation of Br-trihalomethanes by nanosized TiO2/diatomite hybrid photocatalyst

Resumo

Nanosized TiO₂/diatomite catalyst was prepared by sol–gel method at ambient temperature. Diatomite was used as a carrier, tetrabutyl titanate served as a source of titanium. The photocatalytic degradation of Br-THMs was successfully achieved in the presence of TiO₂/diatomite under Xe-light irradiation. It was suggested that Br-THMs were debromized in a stepwise manner. The rate of degradation increases markedly with increasing extent of substitution of Br-THMs by bromine because the C–Br bond is less stable than the C–Cl bond. Furthermore, the degradation of Br-THMs was caused by the action of hydroxyl free radicals, the signals of which were registered by means of electron spin resonance (ESR) spectroscopy.