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Visible light activated photo-catalytic effect and local structure of iron silicate glass prepared by sol-gel method

A relationship between methylene blue (MB) decomposition ability under visible light and local structure of xFe2O3·(100-x)SiO2 glass abbreviated as xFS prepared by sol-gel method was investigated by 57Fe-Mössbauer spectroscopy, X-ray diffractometry (XRD) and ultraviolet-visible light absorption spectroscopy (UV-Vis). Mössbauer spectra of xFS glass with x of 10, 30 and 50 annealed at 1000 °C for 3 h were mainly composed of a paramagnetic doublet due to fayalite (Fe2SiO4), and magnetic sextets due to magnetite (Fe3O4) or hematite (α-Fe2O3). The absorption area (A) of α-Fe2O3 gradually increased from 0.0 to 10.3 and 100 % with the increasing Fe2O3 content (x) of annealed xFS glass. A leaching test performed by 20 mL of MB aqueous solution and 40 mg of annealed 50FS glass showed that MB concentration decreased from 16.2 to 4.7 μmol L-1 after 2 h with the first order rate constant of 1.8 ×10-4 s-1. These results prove that annealed iron silicate glass containing α-Fe2O3 can decompose MB effectively under visible light irradiation.

Iron silicate glass ; Methylene blue ; Photo-catalytic effect ; Sol-gel method

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