The Effect of High Pressure on the Kaolinite Structure

Abstract

AbstractIn the course of the study, samples of kaolin (fraction <0.01 mm) were treated with pressure in the range from 0 to 800 MPa. The obtained samples were studied using X-ray fluorescence analysis and FTIR spectroscopy. The study of the chemical composition showed that with increasing pressure, the content of aluminum and the ratio Al2O3/SiO2 decreases, and the content of SiO2 increases. Probably, the destruction of bonds occurs with the removal of aluminum atoms from the octahedral network of kaolinite, which prevails in the composition of the sample.The FTIR spectra were applied to measure various parameters, the most representative of which are the wavenumber and the integral intensity of the corresponding reflection. Thus, a decrease of parameters indicates a reduction of the “strength” of bonds between aluminum and OH-groups in kaolinite treated by pressure. Moreover, more noticeable changes occur in the range up to 150 MPa.The reflection area of the δH-O-H bond is rising at pressures up to 150 MPa, and then slightly decreases. It is possible to assume some ordering of the kaolinite structure to a mark, and then a subsequent increase in the defectiveness at higher pressures. The reason for the increase in defectiveness may be the destruction of hydrogen bonds between adjacent layers of kaolinite, which conforms to the results of previous studies.KeywordsKaolinPressureFTIRSpectroscopy