Physical refining of crude palm oil includes three major stages: degumming, bleaching and deodourisation. Bleaching earth is used for the removal of undesirable components such as phospholipids, colorants and traces of heavy metals contained in crude oil (Sabah et al., 2007). Regeneration of spent bleaching earth can be achieved by heat treatment (Mahramanlioglu et al., 2010), with solvent extraction (Al-Zahrani and Alhamed, 2000), or by a combination of these methods (Wambu et al., 2009). During these treatments, the chemical composition, structure and textural properties of the clay would be altered. Kheoh (1987) studied the reactivation of spent bleaching clay, which involved washing the bleaching clay with an organic solvent to remove oil, fats, coloured compounds and organic impurities, with subsequent solvent removal.
* Malaysian Palm Oil Board (MPOB),
6 Persiaran Institusi, Bandar Baru Bangi,
43000 Kajang, Selangor, Malaysia.