A Raman and infrared spectroscopic study of the sulphate mineral aluminite Al2(SO4)(OH)4·7H2O

Abstract

The mineral aluminite has been studied using a number of techniques, including scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDX) and Raman and infrared spectroscopy. Raman spectroscopy identifies multiple sulphate symmetric stretching modes in line with the three sulphate crystallographically different sites. Raman spectroscopy also identifies a low intensity band at 1069 cm(-1) which may be attributed to a carbonate symmetric stretching mode, indicating the presence of thaumasite. The observation of multiple bands in this ν4 spectral region offers evidence for the reduction in symmetry of the sulphate anion from Td to C2v or even lower symmetry. The Raman band at 3588 cm(-1) is assigned to the OH unit stretching vibration and the broad feature at around 3439 cm(-1) to water stretching bands. Water stretching vibrations are observed at 3157, 3294, 3378 and 3439 cm(-1). Vibrational spectroscopy enables an assessment of the molecular structure of aluminite to be made.

Crystal-Chemistry of Sulfates from the Apuan Alps (Tuscany, Italy). VII. Magnanelliite, K3Fe3+2(SO4)4 (OH)(H2O)2, a New Sulfate from the Monte Arsiccio Mine

“…Symmetric bending vibrations ν 2 occur at 372, 435, 474, and 502 cm −1 , whereas bands at 576, 606, and 635 cm −1 can be attributed to ν 4 antisymmetric bending modes. The band at 848 cm −1 can be interpreted as due to librations of H 2 O groups, in agreement with previous authors (e.g., [19,20]). Finally, bands at wavenumbers lower than 300 cm −1 (147, 206, 243, and 286 cm −1 ) can be related to lattice vibrations and Fe-O modes.…”

Long‐term atmospheric corrosion rates of hot dip galvanised steel and zinc‐aluminium‐magnesium coated steel

“…The spectra for Qingdao and Jiangjin are similar for 2 and 6 years exposure but there is a tendency that the carbonate peak due to Zn/Al–CO 3 2‐ has increased after 6 years. However, bands due to sulphate, hydroxyl groups and water molecules are dominating the spectra (Figure ) and these are due to the presence of zinc and aluminium hydroxy sulphates, but the formation of Zn/Al‐SO 4 2‐ LDH is possible as well as Zn/Al‐Cl − LDH and aluminium hydroxyl chlorides in Brest and Qingdao. It could be assumed that sulphate and chlorides are accumulated close to the front/bottom of the localized corrosion attacks, as seen for ZM material containing 2% Al and 2% Mg, while Zn/Al–CO 3 2− phases are formed on the outer parts of the corroded coating.…”

“…It could be assumed that sulphate and chlorides are accumulated close to the front/bottom of the localized corrosion attacks, as seen for ZM material containing 2% Al and 2% Mg, while Zn/Al–CO 3 2− phases are formed on the outer parts of the corroded coating. It could be noted that zinc and alumnium hydroxysulphate and Zn/Al‐SO 4 2− LDH can transform to carbonates in the presence of CO 2 , which will absorb readily in the thin electrolyte film at the cathodic areas in the outer part of the coating. It should be noticed that no corrosion products containing magnesium were observed.…”

Insight into the SO2 poisoning of heterobimetallic FeCu‐SSZ‐13 zeolite in NH3‐SCR reaction

“…The typical Raman bands at 480 and 510 cm −1 are ascribed to the υ s (TOT) mode of a combination of 4MR, 6MR, and 8MR in CHA structure 33,34 . In the spectra of the poisoned catalysts, the intensity of the peak at 480 cm −1 is significantly increased due to the superposition of the symmetric bending vibration peak of ѵ 2 (SO 4 2− ) at 482 cm −1 , and the new peak at 186 cm −1 is ascribed to Al‐O from Al 2 (SO 4 ) 3 35 . It is possible that some TOT bonds in the FeCu‐SSZ‐13 framework are broken due to SO 2 poisoning, suggesting the partially damaged framework of the catalyst, 36,37 which is consistent with the XRD results.…”