Clay Characterization and Optimisation of Bleaching Parameters for Palm Kernel Oil Using Alkaline Activated Clays

Abstract

The optimum bleaching parameters (clay dose and bleaching time) for palm kernel oil were determined using alkaline activated clay locally sourced in Nigerian. Activation was carried out using NaOH and KOH. The raw and activated clay samples were characterized using XRD and XRF. Bleached oil was analyzed for % colour reduction (%CR) and percentage free fatty acid (FFA) content before and after bleaching. Alkaline activation resulted to total dissolution of Mg2+ and Ca2+ ions in the octahedral sheet. The activation also affected the tetrahedral sheet by reducing the % composition of the silica and alumina ion after the modification. The results showed that alkaline activation had significant effect on mineralogical and chemical composition of the clay samples. The optimum bleaching conditions (clay dosage and bleaching time) of 3%/weight of oil and 30 mins resulted in 33.3% CR and %FFA of 2.2. It was discovered that NaOH activated clay resulted to higher %CR while KOH activated clay shows affinity for reduced %FFA but at higher concentration of 5 M. This research has further established that alkaline activated clays are feasible alternative for acid activated clays in vegetable oil bleaching.