Physicochemical features of natural clays

The physicochemical features of natural clays were studied using X-ray powder diffraction, chemical analysis, thermal analysis, spectral analysis, EPR, and IR spectroscopy. The major clayey components of the natural clayswere kaolinite and smectite. Their content in the samples ranged from 30 to 95%. EPR detected Mn 2 + , Fe 3 + , and V 4 + ions, as well as hole centers Al-O - and Al-O - -Al. The blue color of the natural clays correlates with the occurrence of trace vanadyl VO 2 + complexes. The sorption properties of the clays were studied in relation to Co, Ni, Sr, Cs, Ca, and Mg. Paramagnetic centers (PCs) were found to affect the sorption.