Изменение физико-химических свойств глин, подверженных давлению

Abstract

Clays represent complex polymineral formations. The properties of clays, including sorption, are largely determined by the structure of their crystal lattice, mineral composition and particle size distribution, as well as by environmental conditions. The mineral composition of clays is represented by the energy on the surface of particles; and the particle size distribution is represented by the active surface area of particles. These two complex parameters mainly determine the sorption activity of clays. To change the sorption activity of clays, the latter are subjected to mechanical treatments, thermal modifications, and chemical activations with the use of chemical agents such as acids, alkalis, salts at various exposure times. Therefore, a study of patterns of changes in the structure and sorption properties of clays subjected to pressure was conducted. Experimental studies have shown that if kaolin is subjected to pressure, defects are formed in the structural pack of kaolinite mineral due to the removal of Al3+, Fe3+/2+, Mg2+, Si4+ ions from it. In this case, pressure has the maximum influence on the removal of Al3+ ions from the pack. As a result of the removal of ions, the formation of the defects deforms the crystal lattice of kaolinite. Data obtained through IR spectroscopy confirm the increase of defectiveness (irregularity) of the structure of kaolinite. It has been revealed that when kaolin is subjected to a pressure of 0–150 MPa, the sorption activity mostly depends on рН of the diffuse layer particle solution ZрН = 73 % and crystallite defectiveness degree ZМк = 24 %. The specific surface area of particles ZSsa = 1 % and kaolinite pack defectiveness Zс = 2 % do not have any significant influence on sorption. If kaolin is subjected to a pressure of 150–800 MPa, kaolin sorption activity mostly depends on kaolinite pack defectiveness Zс = 74 % and crystallite pack defectiveness ZМк = 19 %. The specific surface area of particles ZSsa = 3 % and рН of the diffuse layer particle solution ZрН =4 % do not have any significant influence on sorption.