The efficiency of clays in bleaching degummed palm oil depended on their
unique characteristics. The characteristics of bentonites and
Na-bentonites, including activated forms of both clays, were
investigated in depth to determine their bleaching capacity. The results
showed that Na–bentonite treated with 1.5 M
H2SO4 at a clay:acid ratio of 10:50
(w/v) and refluxing time of 8 h had higher bleaching capacity (78.04%)
than commercial clay (67.09%). X-Ray Diffraction (XRD) patterns of
bentonites and Na-bentonites activations show peaks similar to
montmorillonite. Meanwhile, X-ray Fluorescence Spectrometry (XRF)
indicated a correlation between the SiO2 and
Al2O3 contents of clays and their
bleaching capacity. Interestingly, the high bleaching capacity of
Na–bentonite was correlated with SiO2 and
Al2O3 contents in the range of
72.30–85.20% and 8.96–13.30% by weight, respectively. Moreover, the
specific surface area and total pore volume of this activated clay also
increased. In addition, after bleaching by Na–bentonite treated with
1.5 M H2SO4, the degummed palm oil
appeared to be of good quality, leading to less deterioration and
rancidity. Moreover, the bleached palm oil had lower yellowish colour,
moisture content, and peroxide values than the degummed palm oil.