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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 main aim of this work was to synthesize calcium phosphate silicate bioceramics by a low energy-consuming sol-gel method applying various phosphorous precursors (triethyl phosphate, phosphoric acid, and ammonium hydrogen phosphate). The investigations concentrated on the influence of phosphorous initial compounds on the bond and crystalline structures and the material quality. The application of the alkoxide and inorganic P-precursors results in considerably different textures. The inorganic PO4-containing precursors lead to sol formations. The sol systems can be characterized by a randomly bonded aggregate structure. Monolith gel systems can only be prepared by using TEP. The alkoxide P-precursor more effectively furthers the connection between the phosphorous and silicon tetrahedra than the inorganic phosphate compounds. Over the P-precursors, the catalyst also affects the structure and properties. In the present work, a special attention was paid to identify the POSi bonds in the FTIR and 31P NMR spectra. The bond systems were investigated by FTIR, 31P and 29Si MAS NMR spectroscopies, the morphology by SEM, WAXS, and XRD measurements, and the water solubility of the ceramic systems also was tested.

A relationship between the local structure and the visible-light activated photocatalytic effect was investigated in the glass and glass ceramics prepared by recycling waste slag, which was discharged from a Tokyo Household Garbage Combustion Plant. For the preparation of a homogeneous sample of waste slag recycled glass, (WSRG), 10 wt% of Na2CO3 and 10–50 wt% of Fe2O3 were added. 57Fe-Mössbauer spectra of WSRG recorded at liquid nitrogen temperature showed three types of magnetic hfs; one due to FeII(O h) with δ of 1.21 mm s−1 and H int of 46.7 T, one due to FeIII(O h) with δ of 0.46 mm s−1 and H int of 44.1 T, and the other due to FeIII(T d) with δ of 0.38 mm s−1 and H int of 47.8 T. They were superimposed on a relaxation spectrum due to superparamagnetic hematite. Methylene blue (MB) degradation test with 40 mg of the heat treated WSRG (50 wt% Fe2O3), under the visible-light irradiation for 6 h showed a marked decrease in the concentration of MB from 20 to 7.7 μmol L−1 with a rate constant (k) of 2.7×10−3 min−1 which was close to the k, 9.26×10−3 min− 1, recently obtained in 15Na2O⋅15CaO⋅40Fe2O3⋅ 11Al2O3⋅19SiO2 glass.

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.

This paper systematically examines the influence of the level of Fe(III) doping on the crystal structure and other properties of Ni(OH)(2). Reference beta-Ni(OH)(2) and Fe-doped Ni(OH)(2) samples were synthesized by hydrothermal precipitation of mixed Ni(II) and Fe(III) nitrate aqueous solutions in a highly alkaline medium. The samples were investigated using X-ray powder diffraction (XRPD), scanning and transmission electron microscopy (FE-SEM and TEM), energy dispersive X-ray spectroscopy (EDS), Mossbauer spectroscopy, magnetic measurements, Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy, thermogravimetric analysis (TGA) and electrochemical measurements. Incorporation of Fe in beta-Ni(OH)(2) by cation substitution was confirmed from the shifts in position of XRPD lines due to the difference in the ionic radius of Fe3+ and Ni-2. The Fe-3-for-Ni2+ substitution in beta-Ni(OH)(2) caused formation of an interstratifled structure with beta-Ni(OH)(2) and alpha-Ni(OH)(2) structural units interconnected within the same structural layers and crystallites. Mossbauer spectra revealed the presence of Fe3+ ions in highly distorted octahedral sites, presumably at the boundary between the alpha-Ni(OH)(2) and beta-Ni(OH)(2) structural units within the same structural layer. Electrochemical measurements showed significant increase in oxygen evolution reaction (OER) catalytic activity of Fe-doped Ni(OH)(2) compared to pure phase. (C) 2018 Elsevier B.V. All rights reserved.

Highly porous alumina systems were aimed to produce by low energy-consuming sol–gel and freeze drying techniques. A 3D molecular gel structure derived by sol–gel method is provided as a precursor for vacuum freeze drying process. The typical inorganic precursor is an aqueous colloid solution such as sol or suspension. The new type of precursor results in a new columnar pore structure. The porous system keeps their high porosity even above 1500 °C in contrast with the reported heat resistance value (

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