SEM, EDS and vibrational spectroscopic study of dawsonite NaAl(CO3)(OH)2

Ray L Frost; Andrés López; Ricardo Scholz; Ney Pinheiro Sampaio; Fernando A N de Oliveira

doi:10.1016/j.saa.2014.09.114

SEM, EDS and vibrational spectroscopic study of dawsonite NaAl(CO3)(OH)2

Spectrochim Acta A Mol Biomol Spectrosc. 2015 Feb 5:136 Pt B:918-23. doi: 10.1016/j.saa.2014.09.114. Epub 2014 Oct 6.

Authors

Ray L Frost¹, Andrés López², Ricardo Scholz³, Ney Pinheiro Sampaio⁴, Fernando A N de Oliveira⁵

Affiliations

¹ School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia. Electronic address: r.frost@qut.edu.au.
² School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
³ Geology Department, School of Mines, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG 35,400-00, Brazil.
⁴ NanoLab, REDEMAT, School of Mines, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG 35,400-00, Brazil.
⁵ Federal Institute of Minas Gerais, Campus Ouro Preto, Ouro Preto, MG 35,400-000, Brazil.

PMID: 25459617
DOI: 10.1016/j.saa.2014.09.114

Abstract

In this work we have studied the mineral dawsonite by using a combination of scanning electron microscopy with EDS and vibrational spectroscopy. Single crystals show an acicular habitus forming aggregates with a rosette shape. The chemical analysis shows a phase composed of C, Al, and Na. Two distinct Raman bands at 1091 and 1068 cm(-1) are assigned to the CO3(2-) ν1 symmetric stretching mode. Multiple bands are observed in both the Raman and infrared spectra in the antisymmetric stretching and bending regions showing that the symmetry of the carbonate anion is reduced and in all probability the carbonate anions are not equivalent in the dawsonite structure. Multiple OH deformation vibrations centred upon 950 cm(-1) in both the Raman and infrared spectra show that the OH units in the dawsonite structure are non-equivalent. Raman bands observed at 3250, 3283 and 3295 cm(-1) are assigned to OH stretching vibrations. The position of these bands indicates strong hydrogen bonding of the OH units in the dawsonite structure. The formation of the mineral dawsonite has the potential to offer a mechanism for the geosequestration of greenhouse gases.

Keywords: Carbonate; Dawsonite; Hydroxyl; Infrared and Raman spectroscopy.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aluminum Hydroxide / chemistry*
Microscopy, Electron, Scanning
Spectrometry, X-Ray Emission
Spectrum Analysis, Raman*
Vibration*

Substances

Aluminum Hydroxide
dihydroxyaluminum sodium carbonate