Abstract

Background: Photocatalytic materials can be prepared in the supported form in wastewater treating devices. The quartz sphere can be regarded as a suitable support for photocatalytic material since it is transparent to UV irradiation.

Methods: Gd2Ti2O7 was supported on quartz spheres by a sol-gel method in this work to study the effects of calcination temperature on the properties of the composite 30%Gd2Ti2O7/SiO2. The materials were characterized using scanning electron microscopy, transmission electron microscopy, Xray powder diffraction, FT-IR/Far IR spectroscopy, UV-Vis spectrometry, fluorescence spectrophotometry, and surface area and pore analyses.

Results: Crystallization of pyrochlore structured Gd2Ti2O7 starts at 800oC. The FT-IR absorptions of Gd2Ti2O7 occur in the spectra of the samples calcined over 800oC. Band gap energy of the 30%Gd2Ti2O7/SiO2 decreases from 3.66 eV at 600oC to 3.43 eV at 1000oC. The sample calcined at 800oC has the maximum photocatalytic degradation efficiency of 59.5% after 30 min of irradiation.

Conclusion: The increase of calcination temperature leads to a slight cell expansion of pyrochlore structured Gd2Ti2O7 crystals that forms above 800oC. The increase in calcination temperature leads to constant reducing band gap energy of 30%Gd2Ti2O7/SiO2. The maximum amount of hydroxyl radical is produced in the solution containing 30%Gd2Ti2O7/SiO2 calcined at 800oC, accompanied with the maximum ofloxacin degradation efficiency on that sample.

Keywords: Gd2Ti2O7, Photocatalytic, SiO2, support, ofloxacin, degradation.