Equilibrium and Thermodynamic Studies of Stearic Acid Adsorption on Sepiolite

Abstract

This study presents the equilibrium and thermodynamic parameters of the adsorption of stearic acid on sepiolite as a function of temperature. The equilibrium data were applied to linear Langmuir and Freundlich models and the coefficients of determination (r² = 0.849-0.935 for linear Langmuir model and r² = 0.990-0.995 for linear Feundlich model), indicating that the second model was more applicable in the evaluation of equilibrium data at studied conditions. Thermodynamic parameters such as free energy (ΔGº), enthalpy (ΔHº) and entropy of adsorption (ΔSº) were also calculated. These parameters revealed that the adsorption of stearic acid on sepiolite was feasible, spontaneous and exothermic in nature. On the basis of the results, it can be concluded that the sepiolite has a considerable potential for removal of stearic acid from the main sources such as raw and edible soybean, sunflower and olive oils.