Kinetic and Thermodynamic Studies of Crude Palm Oil Bleaching Using Amansea Clay

Abstract

The effectiveness of the bleaching of crude palm oil was carried out using alkaline-activated Amansea clay. The clay sample was sun-dried, ground, sieved and activated with sodium hydroxide (NaOH) and Potassium hydroxide (KOH). The raw and alkaline-activated clay (AAMC) samples were characterized using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and X-ray fluorescence (XRF) analyses. The dosage, temperature and contact time of the process were varied to observe the efficiency of the bleaching process. The results of the characterization indicated that the raw and activated clays were kaolinite and the clay changed significantly after activation. The bleaching efficiency improved with an increase in temperature and an increase in the mass of the adsorbent. The highest bleaching efficiency of 83.2% was obtained. The pseudo-second-order model best described the adsorption process at 100 oC. The Temkin isotherm model best fitted the experimental data when compared to the other isotherm models because it gave the highest R2 values of >0.9 at all temperatures. The thermodynamics studies carried out from the experimental data indicated that the process was endothermic with an increase in randomness at the solid/liquid interface. The values of the enthalpy and entropy were evaluated as 6.193 KJ/mol and 173.50 J/mol respectively. The adsorption of crude palm oil became spontaneous at 363 and 373 K due to the negative values of Gibb’s free energy obtained at those temperatures. The experimental result indicates that 83.2% bleaching efficiency can be from bleaching crude palm oil with alkaline-activated Amansea clay.