Background: B-TiO2 was supported on the surface of iM16K glass bubbles to achieve a
suitable density for the B-TiO2/iM16K composite hollow spheres. Aeration or stirring in the wastewater
can lead to thorough mixing of photocatalyst and wastewater. Solid-water separation is relatively
easy because the materials can float on the water surface while stopping aeration or stirring.
Methods: The iM16K glass bubbles were used to prepare boron-doped B-TiO2/iM16K composite
hollow spheres through a sol-gel route. The materials were characterized by X-ray diffraction, scanning
electron microscope, Fourier transforms infrared spectroscopy, UV-Visible diffuse reflectance
spectrometry, and N2 adsorption-desorption techniques. The photocatalytic degradation of azophloxine
on the composites was determined.
Results: The bandgap energy of the B-TiO2/iM16K composite was slightly less than 3.0 eV when the
calcination temperature was below 500°C. The sample calcined at 350°C had a BET surface area of
88.6 m2/g, while the value of the sample calcined at 800°C was 1.2 m2/g. The maximum photocatalytic
degradation efficiency was obtained for the sample calcined at 450°C, and nearly all of the
original azophloxine molecules were decomposed after 120 min of irradiation. Photocatalytic degradation
efficiency after 30 min of irradiation was enhanced from 18.8% to 47.9% when the B-TiO2
dosage increased from 100 to 800 mg/L.
Conclusion: Crystallization of anatase TiO2 was temperature-dependent, and the properties of BTiO2/
iM16K composite hollow spheres were affected by the phase composition of the boron-doped
TiO2 layer. The change in calcination temperature can have a significant effect on the photocatalytic
degradation of azophloxine. The production of hydroxyl radical depended on the photocatalytic activity
of the B-TiO2/iM16K composite hollow spheres.