Removal of Pigments from Palm Oil Using Activated Ibusa Kaolinite: Equilibrium, Kinetic and Thermodynamic Studies

Abstract

The effectiveness of Ibusa kaolinite as an adsorbent in removing pigments from palm oil has been investigated in this study. Ibusa kaolinite was prepared as an adsorbent by treating it with hydrochloric acid. The surface area of the clay was found to increase with increase in acid dosage up to a maximum and then de-creased while its cation exchange capacity decreased with increase in acid dosage. The activated clay was used as an adsorbent for the removal of pigments from palm oil. The bleaching process was investigated by varying the clay dosage, acid concentration and temperature. The highest removal of pigments was recorded at 7 M HCl concentration, 4 g clay dosage and 100°C temperature, and about 97.4% pigments were removed in 80 minutes. Four isotherm models, three kinetic models, and the intra-particle diffusion model were applied to fit the experimental data. It was found that the equilibrium data were best represented by the Temkin isotherm model. The experimental data fitted well the pseudo-second-order kinetic model. Diffusion studies indicated that in-tra-particle diffusion is not the sole rate-controlling factor. The bleaching pro-cess was found to be spontaneous and endothermic, with increasing random-ness of adsorbed species.