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Abstract
Bayer hydrotalcites prepared using the seawater neutralisation (SWN) process of Bayer liquors are characterised using X-ray diffraction and thermal analysis techniques. The Bayer hydrotalcites are synthesised at four different temperatures (0, 25, 55, and 75 °C) to determine the effect of synthesis temperature on the thermal stability of the Bayer hydrotalcite structures and the mineralogical phases that form. The interlayer distance increased with increasing synthesis temperature, up to 55 °C, and then decreased by 0.14 Å for Bayer hydrotalcites prepared at 75 °C. The three mineralogical phases identified in this investigation are; (1) Bayer hydrotalcite, (2), calcium carbonate species, and (3) hydromagnesite. The DTG curve can be separated into four decomposition steps; (1) the removal of adsorbed water and free interlayer water in hydrotalcite (30–230 °C), (2) the dehydroxylation of hydrotalcite and the decarbonation of hydrotalcite (250–400 °C), (3) the decarbonation of hydromagnesite (400–550 °C), and (4) the decarbonation of aragonite (550–650 °C).
understanding of the formation of hydrotalcite produced from the seawater neutralisation of Bayer refinery liquors, hydrotalcites were synthesised in the laboratory using aluminate and magnesium solutions. One of the aims of this investigation is to establish
. Palmer SJ , Frost RL . Characterisation of bauxite and seawater neutralised bauxite residue using XRD and vibrational spectroscopic techniques . J Mater Sci . 2009 . doi: 10.1007/s10853-008-3123-y
