Adsorption of fatty acids from solutions in organic solvents on the surface of finely dispersed magnetite: 2. heats of oleic, linoleic, and linolenic acid adsorption from carbon tetrachloride and hexane

Differential and integral heats of oleic, linoleic, and linolenic acid adsorption on the surface of finely dispersed magnetite from solutions in carbon tetrachloride and hexane are measured by the calorimetric method. The thermodynamic parameters of the adsorption for the systems under examination are calculated from the obtained experimental data. It is discovered that, at low concentrations, the volume filling of micropores in the particle aggregates of the adsorbent occurs with the formation of ordered adsorbate structures in the pores. At high concentrations, the fatty acids are adsorbed in mesopores and on the outer surface of the adsorbent. It is shown that, at high concentrations, the key contributions to the integral heat of adsorption are made by the endothermic processes of desolvation of adsorbates and the adsorbent surface, as well as by the competitive adsorption of solvent and fatty acid molecules on the active sites of the adsorbent surface.