Preparation of diatomite–TiO₂ composite for photodegradation of bisphenol-A in water

Abstract

To enhance the photodegradation performance of pure titanium dioxide (TiO₂), diatomite was used as a porous carrier to immobilize TiO₂ powders using calcination method. The photodegradation of bisphenol-A (BPA; 4,4′-isopropylidenediphenol), which has been listed as one of endocrine disrupting chemicals, was carried out in a batch suspension reactor using pure TiO₂ powders and diatomite–TiO₂ composites, respectively. Under the controlled conditions, the photocatalytic efficiencies of the BPA degradation by the diatomite–TiO₂ composites can be found to be higher than those by pure TiO₂ powders. This result should be attributable to the accessibility of the BPA molecules to the surface of TiO₂ particle in the modified photocatalysts, showing that the enrichment of the organic solute enhanced the rate of photodegradation on the diatomite–TiO₂ composite. However, the photodegradation efficiency was not dependent on the pore properties of these TiO₂ photocatalysts. The experimental results further indicated that the photodegradation kinetics for the destruction of BPA in water followed the first-order model well. The apparent first-order reaction constants (k _obs), thus obtained from the fittings of the model, were in line with the destruction-removal efficiencies of BPA in all the photocatalytic experiments.