Mechanosorption of carbon dioxide by Ca- and Mg-containing silicates and alumosilicates. Sorption of CO2 and structure-related chemical changes
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- Kalinkin, A.M., Kalinkina, E.V. & Zalkind, O.A. Colloid J (2009) 71: 185. doi:10.1134/S1061933X09020069
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The discovery of the unusual ability of Ca- and Mg-containing silicates in certain grinding regimes to absorb carbon dioxide from the environment in amounts comparable to the mass of the ground sample has stimulated interest in the study of mechanochemical effects. The range of objects for studying natural minerals, such as labradorite (CaAl2Si2O8)0.562(NaAlSi3O8)0.438, oligoclase (CaAl2Si2O8)0.148(NaAlSi3O8)0.852, diopside CaMgSi2O6, and akermanite Ca2MgSi2O7, as well as synthetic minerals gehlenite Ca2Al2SiO7 and wollastonite CaSiO3, is expanded to develop the model of deep mechanosorption of CO2 and to derive equations that allow the kinetic analysis of the absorption of carbon dioxide by silicates in the course of mechanochemical activation to be performed. Regularities revealed previously and analogies to the processes that occur upon the dissolution of carbon dioxide in silicate melts, are generalized. Data on the absorption of carbon dioxide by Ca- and Mgcontaining silicates and alumosilicates, depending on the duration of mechanochemical activation in an AGO-2 centrifugal planetary mill in the atmosphere of CO2 at a pressure of 105 Pa, are obtained. Based on the data of X-ray phase analysis and IR spectroscopy, structural chemical changes in minerals and the forms of carbon dioxide in mechanochemically activated samples are discussed. It is shown that the intense penetration of gas molecules in particle bulk and their “dissolution” in structurally disordered silicate matrix in the form of distorted CO32− ions occurs upon mechanosorption.