LAYER CHARGE PROPERTIES OF SMECTITES AND VERMICULITES - TETRAHEDRAL VS OCTAHEDRAL

Total layer charge and charge of octahedral sheets of 2:1 soil clays were estimated by combining alkylammonium ion exchange technique and the Hofmann and Klemen effect. The estimation of charge before and after Hofmann and Klemen effect (Li-saturation and heat treatment) gave the total layer and tetrahedral charge, respectively. The difference of total and tetrahedral charge provided the charge contribution of octahedral sheets, assuming that a complete neutralization of octahedral charge was achieved by Li** plus migration during the heat treatment. As much as 50% of the charge was found to be located in the octahedral sheets in soil smectics and soil vermiculites.