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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).
(Na[Al(OH) 4 ]). The pH of solution was decreased to pH 12 using 0.1 M hydrochloric acid (HCl). The pH of Bayer liquor is generally greater than 12, therefore aluminate solutions were prepared in a similar pH range. The aluminate hydrotalcites were
nucleation of gibbsite crystals from synthetic Bayer liquors: effect of alkali metal ions . J Cryst Growth 219 : 451 – 464 10.1016/S0022-0248(00)00734-X . 5. Gonçalves JF
Thermal decomposition of SO42−-intercalated Mg–Al layered double hydroxide
Elimination behavior of sulfur oxides
coordination of anions in Bayer liquors: anion binding in layered double hydroxides . Coord Chem Rev . 253 : 250 – 267 10.1016/j.ccr.2008.01.012 . 4. Auxilio , AR , Andrews , PC , Junk , PC
of alumina by the conventional Bayer process [ 5 – 7 , 9 ]. During the refining process, this clay is attacked and dissolved into the Bayer liquor. The dissolved silica reprecipitates as a sodium aluminum silicate, also known as Bayer desilication
of anions in Bayer liquors: anion binding in layered double hydroxides . Coord Chem Rev 253 : 250 – 267 . 48. Jinesh , CM , Antonyraj , CA , Kannan , S 2010 Allylbenzene
