Acid-activated montmorillonite from Marapi ash for enhanced crude palm oil bleaching

This study aims to evaluate the characteristics and bleaching performance of montmorillonite (MMT) obtained from volcanic ash at Mount Marapi, West Sumatra, Indonesia, after undergoing purification and acid activation processes. Activation was carried out using sulfuric acid solution, and material characterization was carried out using X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results indicated that acid activation caused octahedral metal ions (Al, Fe and Mg) to leach out, the crystallinity to decrease, the functional groups to change, and the porosity and surface area to increase. Bleaching tests on crude palm oil showed that acid-activated MMT was able to reduce moisture up to 0.13%, free fatty acids up to 0.31%, and β-carotene up to 299.42 ppm. In addition, the oil viscosity decreased from 60.29 to 38.60 cSt, and the refractive index from 1.70 to 1.46, indicating an improvement in the oil’s clarity and physical quality. Thus, the acid-activated MMT from Marapi volcanic ash shows potential as an effective adsorbent in refining palm oil.