Desorption of β-carotene from bentonite adsorbent under microwave irradiation

Abstract

The desorption behavior of β-carotene from a bentonite adsorbent under microwave irradiation in isopropanol was studied as a function of temperature and different initial loading concentrations. A first-order, two-component, three-parameter model described the desorption kinetics with a coefficient of de-termination R2 > 0.9932, and the β-carotene desorption process under microwave irradiation was con-trolled by both rapid and slow desorption. The activation energies of β-carotene desorption for the rapid and slow desorption processes were 19.61 and 53.04 kJ mol-1, respectively. It was observed that the de-sorption equilibrium data fitted well to both the Freundlich and Langmuir isotherms. The data obtained from the desorption-isotherm model were used to determine the thermodynamic parameters. The positive value of free energy indicates the non-spontaneity of β-carotene desorption. The change in entropy rela-tive to the enthalpy of desorption reveals that the reaction is physical in nature.