This paper studies the thermodynamic aspects of the processes of adsorption of phenol from dilute aqueous solutions on different commercial carbons, evaluating how to optimize the removal of this persistent contaminant. Two powdered activated carbons from two different companies were used: Tetrahedron Carbon (Andes Chemistry Lab., Mendoza, Argentina), and Norit (Norit Americas Inc., USA). Both specific surface areas were measured by means of the BET method. The adsorbate was high purity solid phenol (Fluka ® ≥ 99.5%). Experimental isotherms were determined at 293 K, 303 K and 313 K. The Freundlich and Sips theoretical models were used to fit the experimental data. Freundlich isotherm slightly diverges with the experimental results for higher equilibrium concentrations. Thermodynamic parameters were calculated and correlated with the adsorption behaviours. The values of the thermodynamic parameters obtained indicate an exothermic and spontaneous process for both carbons, and mainly for Norit. This is due to the fact that there might be chemically activated regions on the surface of the Norit carbon, which give rise to combined mechanisms of physisorption and chemisorption.

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Physical adsorption of SO 2 on exfoliated graphite is studied using classical adsorption volumetry and Monte Carlo computer simulations. The experimental isotherms have been obtained in a wide temperature range to determine the critical temperature for the completion of several layers. The computer simulations are in good agreement with the experimental data. The adsorption potential is analyzed and the results are employed to interpret the distributions of adsorbed molecules according to the gas-solid energy. The adsorbed phase exhibits a certain degree of order in an incommensurate phase with respect to the graphite surface. From the simulations, the structure of the adsorbed phase is analyzed, and the unit cell edge length is estimated.