Interlamellar adsorption of organic pollutants on organophilized montmorillonite.

The sorption of nitrobenzene, 2-chlorophenol and 4-chloro-phenol from water on hydrophobic montmorillonite was studied. Excess adsorption isotherms we re obtained by the immersion method. The basal spacings of the clay mineral were determined by X-ray diffraction. Positive adsorption of the organic c omponents is observed in the whole range of compositions (up to x(1,r) = 1) . The results of X-ray diffraction measurements are in good agreement with the excess isotherms: whenever a region of the isotherm indicates an increa se of the organic component, an increase in basal spacing is also observed. By combining these two independent methods, the composition and structure of the interlamellar space could be accurately calculated. The free enthalp y change of adsorption and the adsorption capacity is calculated by analyzi ng the adsorption isotherm on the basis of the Gibbs equation and Everett-S chay method. The results are utilizable for the planning of environmental p rocedures and systems (water purification, soil remediation). Within the organocomplexes of well-ordered structure, basal spacings range from 3.06 to 3.65 nm, depending on the structure of the pollutant and the a dsorbed material.