Low-density TiO2-glass bubble composite for azophloxine degradation

Abstract

The glass bubbles were used to support the TiO2 via a sol–gel route to synthesize the low-density TiO2-GB composite materials. The composites could be suspended in the azophloxine solution under gentle stirring to obtain a high degradation efficiency. The anatase TiO2 crystallite size was <10 nm in the composites calcined below 450 °C. The TiO2-GB composites prepared at 350, 450, 650, and 800 °C had the bandgap energies of 3.17, 3.13, 3.15, and 3.24 eV, respectively. The TiO2-GB composite calcined at 800 °C had the strongest photoluminescence intensity, followed by the samples calcined at 350, 650, and 450 °C. The change in calcination temperature could greatly influence the pore volume, surface area, and pore size in the composites. The reaction rate constants were 1.38 × 10−3, 9.78 × 10−3, and 9.08 × 10−3 min−1, calculated for azophloxine degradation on the TiO2-GB composites prepared at 350, 450, and 650 °C. The TiO2-GB composite calcined at 450 °C could produce the greatest hydroxyl radicals during the photocatalytic reaction, followed by the samples calcined at 650, 350, and 800 °C.