Thermodynamics and mechanism of nicotine adsorption onto hydrophobic zeolite type usy from aqueous solution

Abstract

The isothermal adsorption of nicotine from an aqueous solution onto zeolite type USY at temperature range from 298 to 322 K was investigated. It was found that the adsorption isotherms can be described by the Freundlich adsorption isotherm. The density distribution function of adsorption centers has an exponential form and the adsorption isotherms can be fitted by the Freundlich isotherm. The changes of adsorption heat, free energy and entropy with the adsorption degree were determined on the base on the adsorption isotherms. The decrease of adsorption heat with the adsorption degree is explained by the presence of energetic heterogeneity of the adsorption centers on the interface. The increase of entropy with the adsorption degree can be explained with the change of the type of adsorption and with the phase state of adsorbed nicotine which has a structure different than liquid nicotine.