Kinetics, Equilibrium and Thermodynamic Studies on Removal of Oleic Acid from Sunflower Oil onto Amberlyst A21

Amberlyst A21 was used for the oleic acid adsorption from sunflower oil (SFO). The impacts of parameters such as contact time, temperature, and mass ratio of adsorbent on oleic acid adsorption were studied. The characterization of Amberlyst A21 before and after adsorption was performed by using Fourier transform infrared spectrometer (FTIR) and scanning electron microscope (SEM). The adsorption reached equilibrium 480 minutes later. The increase in temperature and the amount of adsorbent caused an increase in the amount of adsorbed oleic acid. The adsorption kinetics, isotherms, and thermodynamics were studied. The pseudo-first order kinetics well described the adsorption for all studied temperatures. The Langmuir, Freundlich, and Dubinin−Radushkevich isotherms and thermodynamic analysis were investigated at equilibrium. The suitability of the Langmuir and Freundlich isotherms indicated that the adsorption takes place under monolayer and heterogeneous surfaces. Thermodynamical results showed that adsorption occurs spontaneously and endothermic