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 determination R2 > 0.9932, and the β-carotene desorption process under microwave irradiation was controlled 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 desorption 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 relative to the enthalpy of desorption reveals that the reaction is physical in nature.

Keywords

• β–carotene
• desorption
• bentonite
• microwave irradiation
• kinetics