Papers by Keyword: Bischofite

Abstract: Non-traditional colour solutions used by designers in the design of building exteriors and interiors are driving a rapid increase in demand for locally produced decorative building materials. The modern pigments market offers a wide range of products, but not all of them satisfy consumer requirements, particularly regarding colour range. Inorganic pigments are characterised by high resistance to light and weather conditions, but organic pigments provide the greatest variety and brightness. Due to the significant rise in energy costs, which in turn has increased the price of Portland cement, more attention in Ukraine is being given to the research and application of magnesia-based binders. One of the advantages of these binders is that they require significantly less energy for production compared to lime and Portland cement.

Abstract: Anhydrous magnesium chloride (MgCl2), the dehydration product from bischofite (MgCl2•6H2O) and as industrial raw material for preparation of electrolytic magnesium, is now the most advanced and perfect technological process. For long, the detailed dehydration process was not known due to its dehydration complexity and lack of appropriate experimental conditions. In this paper, quantum chemistry method based on density functional theory (DFT) was used to study the whole dehydration processes. The molecular geometries of MgCl2•6H2O, MgCl2•4H2O, MgCl2 •2H2O, MgCl2•H2O and MgCl2 were all optimized at level of B3LYP/6-31G*, the optimized geometrical parameters and correspondent energies corrected by the second order Møller-Plesset perturbation theory (MP2) were thus obtained. Results show that the energy variations corresponding to the whole dehydration steps from MgCl2•6H2O via intermediates MgCl2•4H2O, MgCl2•2H2O and MgCl2•H2O, to anhydrous product MgCl2 are 35.55, 41.30, 28.55, 31.08kcal/mol, respectively. For steps of 2H2O removal, the energy variation from MgCl2•2H2O to MgCl2 is 59.63kcal/mol, bigger than the steps from MgCl2•6H2O to MgCl2•4H2O (35.55kcal/mol) and from MgCl2•4H2O to MgCl2•2H2O (41.30kcal/mol), which means the last two water molecules are the most difficult to be removed. All these results are significant for mechanism study of bischofite dehydration and are helpful for industrial production of anhydrous magnesium chloride.