Calcination effects on sol–gel preparation of porous TiO2/zeolite composites for Acid Red 1 degradation

Abstract

A sol–gel synthesizing method was applied to prepare thin porous titanium dioxide layer supported on the zeolite. Hexadecyltrimethylammonium bromide can enhance the porosity of TiO2 layer and the activity. This work aims at the influences of calcination temperature on the characteristics of the TiO2/zeolite composites. The only substance in the supported layer of the TiO2/zeolite composites is anatase TiO2. The crystallite sizes of anatase titanium dioxide in the composites calcined at 350°C, 400°C, 450°C and 500°C are 8.8, 10.0, 11.8 and 12.3 nm, and the bandgap energies are 2.67, 3.08, 3.21 and 3.21 eV for the composites, respectively. The TiO2/zeolite composites are typical mesoporous materials, and the mesopores are formed in the TiO2 layer. The composite sample calcined at 400°C has the largest specific surface area (229.7 m2/g), which is close to that of the zeolite. Many mesopores are formed in the TiO2 layer of the TiO2/zeolite composite. The maximum number of hydroxyl radical is produced on the TiO2/zeolite composite calcined at 400°C, accompanied with the strongest photocatalytic activity. Acid Red 1 dye is almost thoroughly degraded after 90 min of reaction in the presence of the TiO2/zeolite composite.