Structural formula determination of 2:1 Tunisian clay using XRD investigation

摘要

This work aims at determining the structural formula of a Tunisian 2:1 clay using PXRD analysis. To accomplish this goal, exchangeable site of the material was saturated respectively by Li~+, Cs~+ and Ni~(2+) cation. The octahedral charge rate and the structural iron amount were obtained using Li-saturated sample and based on the Hoffman Klemen method. The Cs exchange process was used to determine the total and the tetrahedral layer charge. The Si, Al, Fe and Mg rates were determined using XRD patterns. All these parameters allowed us to establish the structural formula. A Ni-saturated sample was studied to confirm the structural formula calculated above. All structural parameters were determined using an indirect method based on the comparison between experimental and simulated XRD patterns. Final results showed that the studied sample was characterized by an octahedral charge and the following structural formula: (Si_(4.00)) (Al_(1.10) Fe_(0.50) Mg_(0.40)) O_10 (OH)_2 (M~+_(0.4)); M~+ is a monovalent cation.