Kinetic and equilibrium studies of bleaching used palm olein oil using alkaline-activated rice husk

Abstract

In this study, the effectiveness of bleaching used palm olein oil was investigated using alkaline-activated rice husk as an adsorbent. The rice husk sample was activated with potassium hydroxide. Characterization of the raw and the alkaline-activated rice husk (AARH) was carried out using Brunauer-Emmett-Teller and scanning electron microscopy. The AARH shows an improvement in the total surface area (127.210m2/g) compared to that of the raw rice husk (59.520m2/g). Scanning electron microscopy micrograph investigation reveals an improvement in the morphological characteristics of the AARH. The examination of the bleached used palm olein oil using Fourier transform infrared spectroscopy reveals the existence of distinctive functional groups. The pseudo-second-order kinetic model, with a coefficient of determination, R2 of 0.9848, provides the best description of the adsorption process at 80 C. The Temkin isotherm model offered the best and most accurate fitting for the adsorption figures, with the highest values of R2 (0.5395, 0.9967, 0.9650, and 0.9990) at temperatures of 60, 70, 80, and 90 C, respectively. This investigation has proven that rice husk can be converted into an effective and efficient alkaline-activated adsorbent for vegetable oil bleaching.