Ionic-electrostatic model of the wedge pressure and specific surface area of colloidal systemsстатья
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Дата последнего поиска статьи во внешних источниках: 9 октября 2019 г.
Аннотация:A physically substantiated ionic-electrostatic model of the wedge pressure by Deryagin, modifi ed for defi nition of the water retentivity of natural and artifi cial colloidal dispersions with a variable moisture content (soils, grounds, clay minerals, wood, caustobioliths, synthetic polymeric hydrogels), is considered. In this model, the relation between the moisture content and dispersivity (effective specifi c area) of a colloidal system serves as a phase variable. For the fi rst time, with the use of the sorption-equilibrium, moisture-thermodesorption, and equilibrium-centrifugation methods, wedge-pressure isotherms, representing the dependence of the thermodynamic moisture potential (specifi c Gibbs energy) of a material on the mass fraction of moisture in it, were obtained for materials different in genesis and dispersivity, whose thermodynamic moisture potential varies in absolute value within the wide range 0.1–260 kJ/kg, and the wedge pressure of colloid-bonded disperse systems was quantitatively estimated with regard for the variable factors (temperature, composition, liquid-phase concentration) of the aggregative stability of their colloidal complex determining the phenomenon of dynamics of the dispersivity and water retentivity of such systems. A methodology of calculating the effective specifi c area of a material by the slope of its wedge-pressure isotherms, constructed at the logarithmic scale, is proposed as an alternative to the standard Brunauer–Emmett–Teller method. The new method is close to the traditional one in the specifi c area of a material obtained with them, but the method proposed differs favorably from the standard method by the temperature invariance and the possibility of calculating the energy of interphase interactions in the material with the use of the generalized Hamaker constant.