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Equilibrium adsorption of stilbenoids at metal oxides

Research paper by P. N. Kolotilov, K. E. Polunin, I. A. Polunina, A. V. Larin

Indexed on: 10 Feb '09Published on: 10 Feb '09Published in: Protection of Metals and Physical Chemistry of Surfaces



Abstract

The isotherms of adsorption of trans-hydroxystilbenes (stilbenoids) and hydroxybenzenes (phenols) from n-hexane-ethyl acetate (1: 1) at nanodispersed aerogels of aluminum and titanium oxides were measured under static conditions. The adsorption isotherms can be approximated well by the Freundlich equation for the model of localized adsorption at energetically heterogeneous solids. It was found that the adsorption value of both stilbenoids and phenols is improved with an increase in the number of OH groups in their molecules, being sensitive to the chemistry of the adsorbent surface. trans-Hydroxystilbenes adsorb at TiO2 better than do the corresponding phenols. The opposite pattern was observed for Al2 O3. The adsorption of trans-hydroxystilbenes at TiO2 is irreversible and accompanied by the formation of colored surface compounds.