AI Article Synopsis
- Clay minerals have a permanent negative charge and, in sodium salt solutions, sodium ions cover their surface.
- In acidic conditions (pH<4-6), sodium ions are replaced by hydrogen ions due to the dissolution of alumina and subsequent aluminum/sodium exchange.
- Two experimental approaches, measuring exchangeable ions and trace metal sorption, were used to study this exchange process, and results were effectively modeled using the Poisson-Boltzmann equation.
Article Abstract
Clay minerals are specified by permanent negative surface charge. In solutions of sodium salts, the surface of clay is covered by exchangeable sodium ions. In an acidic field (pH<4-6), sodium ions are displaced from the surface. This apparent H/Na exchange is conditioned by dissolution of alumina, followed by Al/Na exchange. Two kinds of published experimental data were considered in order to follow Al/Na exchange: the first is direct measurement of exchangeable sodium and aluminum in clay, and the second is exchange sorption of trace metal. Because of the equivalency of ionic exchange, trace metal acts as a probe, indicating the sodium content in clay. These experimental data were successfully modeled with use of the Poisson-Boltzmann equation, with the assumption that all exchange cations are located in the diffuse layer.
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| http://dx.doi.org/10.1016/j.jcis.2009.04.018 | DOI Listing |
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