Performance Evaluation of Thermal and Acid-activated Smectite in Bleaching Palm Oil

Abstract

Smectite from Ubulu-uku was activated thermally and chemically to increase its adsorptive performance. The thermally and chemically modified samples were analyzed using X-ray Fluorescence (XRF). Thermal activation involved drying in the sun for 24 hours, milling it to a particle size of 0.212 mm and heating at a temperature range of 150 to 750 0C (150, 300, 450, 600, and 7500C). The chemical activation was carried out by immersing the samples in 100 mL of a hydrochloric acid solution. It was determined what the physicochemical properties were, including acidity, cation exchange capacity, oil retention, and surface area. The samples' adsorptive abilities were then evaluated by bleaching palm oil using them. The X-ray fluorescence results showed that the chemical compositions of the samples were altered by both thermal and acid treatments. There were some disappearances of the stretching bands at 3692, 3525, and 1104 cm-1 assigned to the H-O-H stretching. The surface area was also observed to increase in value with the thermal treatment until the temperature reached 600oC. The physicochemical results indicated that the chemically activated samples have a larger surface area, acidity, and lower cation exchange capacity with a bleaching efficiency of 95.8%. In comparison, the thermally activated samples have a lower surface area, acidity, and high cation exchange capacity with a bleaching efficiency of 89.7%. This study has revealed that the performance of local clay minerals can be enhanced by thermal and acid activation.