Irradiation-catalysed degradation of methyl orange using BaF ₂ –TiO ₂ nanocomposite catalysts prepared by a sol–gel method

Abstract

BaF2–TiO2 nanocomposite material (hereinafter called the composite) was prepared by a sol–gel method. The composite surface area, morphology and structure were characterized by Brunauer–Emmett–Teller method, X-ray diffraction analysis and a scanning electron microscopy. The results showed that BaF2 and TiO2 form a PN-like structure on the surface of the composite. Composites were used to catalyse the degradation of methyl orange by irradiation with ultraviolet light, γ-rays and an electron beam (EB). It was demonstrated that the composite is found to be more efficient than the prepared TiO2 and commercial P25 in the degradation of methyl orange under γ-irradiation. Increasing the composite catalyst concentration within a certain range can effectively improve the decolorization rate of the methyl orange solution. However, when the composite material is used to catalyse the degradation of organic matter in the presence of ultraviolet light or 10 MeV EB irradiation, the catalytic effect is poor or substantially ineffective. In addition, a hybrid mechanism is proposed; BaF2 absorbs γ-rays to generate radioluminescence and further excites TiO2 to generate photo-charges. Due to the heterojunction effect, the resulting photo-charge will produce more active particles. This seems to be a possible mechanism to explain γ-irradiation's catalytic behaviour.

Microwave Synthesis of Visible-Light-Activated g-C3N4/TiO2 Photocatalysts

“…After this time, a transparent solution could be observed ( Figure S3f ). The MO degradation ratio (%) was calculated based on Equation (2): where is the initial absorbance of the MO solution before irradiation, and is the absorbance of the MO solution after a certain exposure time (t) [ 23 , 78 , 86 , 113 , 114 ]. Based on Figure S3a–e , it is possible to calculate the ratio between the maximum value of each absorbance spectrum ( ) at each exposure time and the initial absorbance of the solution ( ), as depicted in Figure 10 a.…”