Soybean Oil Bleaching by Adsorption onto Bentonite/Iron Oxide Nanocomposites

ABSTRACT

The bleaching process of soybean oil using commercial bentonite and bentonite/iron oxide composites has been studied. X-ray diffraction (XRD), Brunauer- Emmett-Teller (BET) surface area measurement and scanning electron microscopy (SEM) were used to characterise the composites generated. SEM results show that the porosity of bentonite after alkaline ion exchange process can be enhanced by the opening of the bentonite’s flakes. BET shows that the flakes’ structure was more opened, and the porosity was increased from 179.58 m2 g–1 for bentonite to 202 m2 g–1 for 3 min ion exchanged sample. Changes in basal reflection in XRD peak validated the presence of iron oxide particles. The experimental results indicate that composite prepared for 1 min showed the same efficiency in bleaching crude soybean oil with the bentonite. The greatest reduction in bleaching capacity in soybean oil was achieved using the composite prepared for 3 min. The highest transparency, 1.5-fold in red and 1.25-fold in yellow greater than that of neutralised oil, was obtained with the alkaline ion exchange composite prepared for 3 min. Hence, this process gives a good adsorbent with better bleaching properties than commercial bentonite.

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