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The photo-Fenton properties of iron silicate composite materials were investigated by methylene blue dye degradation. From various iron oxide and iron silicate samples the best performing material, FeSiOx (bulk iron silicate) showed a first-order rate constant of (1.57 ± 0.04) × 10−2 min−1. According to the 57Fe Mossbauer spectra, XRD patterns and TEM images this sample showed the most amount of Fe2+ content in the form of Fe2SiO4 nanoprecipitations.

The relationship between local structure and visible-light photocatalytic ability of tin silicate glass prepared by sol–gel method was investigated. 119Sn Mossbauer spectrum of SnOx SiO2 glass prepared from SnCl2 showed a small peak of SnII component besides the major amount of SnIV. The smallest bandgap energy of 2.5 ± 0.5 eV was estimated from Tauc plot, and the largest first order rate constant (k) of (13.8 ± 0.1) 10-3 min-1 was recorded from the methylene blue degradation test under visible-light irradiation. It is concluded that SnII shows remarkable photocatalytic ability when it is incorporated into silica glass matrix.

A relationship between structure and visible light-activated photocatalytic activity of iron-containing soda lime aluminosilicate (15Na2O⋅15CaO⋅40Fe2O3⋅xAl2O3⋅(30−x)SiO2) glass (xNCFAS) was investigated by means of 57Fe-Mossbauer spectroscopy, X-ray diffractometry (XRD) and UV–visible light absorption spectroscopy (UV–VIS). The 57Fe-Mossbauer spectrum of 11NCFAS glass measured after heat-treatment at 1000 °C for 100 min was composed of a paramagnetic doublet due to FeIII(Td) and two magnetic sextets due to regular hematite (α-Fe2O3) and hematite with larger internal magnetic field. X-ray diffraction patterns of heat-treated xNCFAS samples resulted in decrease of α-Fe2O3 and increase of Ca2Fe22O33 or CaFe2O4 with alumina content. A quick decrease in methylene blue (MB) concentration from 15.6 to 4.7 μmol L−1 was observed in the photocatalytic reaction test with 40 mg of heat-treated 11NCFAS glass under visible light-exposure. The largest first-order rate constant of MB decomposition (k) was estimated to be 9.26 × 10−3 min−1. Tauc’s plot yielded a band gap energy (Eg) of 1.88 eV for heat-treated 11NCFAS glass, which is smaller than previously reported Eg of 2.2 eV for α-Fe2O3. These results prove that addition of Al2O3 into iron-containing soda lime silicate glass is favorable for the preparation of improved visible light-photocatalyst with ‘ubiquitous’ elements.

International journal of molecular sciences 14(5), 9722-9736 (2013). doi:10.18154/RWTH-CONV-085528, Published by Molecular Diversity Preservation International, Basel