Study of the features of water film formation on montmorillonite and kaolinite surfaces by infrared spectroscopy

Kaolinite (KGa-1b) and montmorillonite (STx-1b) reference samples were studied by infrared spectroscopy at various water contents. The spectral features reflecting the formation of water layers on the basal surfaces of individual minerals have been studied. Experimental studies were carried out by the Attenuated Total Reflection (ATR) Fourier Transform Infrared (FTIR) spectroscopy. The analysis of the composition of the wet samples was carried out by decomposing the experimental spectra into the spectrum of H$_2$O and minerals in the air-dry condition. The obtained dependences of the participation coefficients of the basic spectra on humidity are compared with the results of measurements in the microwave range and make it possible to investigate the integral features of the formation of a water layer on mineral particles and to predict the plasticity of clays. The anomalous position of the maximum and the half-width of the stretching vibrational modes of water molecules at low water content have been established.