Regeneration of spent bleaching earth using microwave assisted extraction method with hexane as solvent for the bleaching of crude palm oil

Abstract

One of the wastes in palm oil mills is spent bleaching earth (SBE) which is produced from the bleaching process. In landfills, SBE can produce unpleasant odors, pollute the land and can be quickly oxidized and spontaneously auto ignition occurs. SBE consists of residual oil, phospholipids and several minor components resulting from the bleaching process. Microwave-assisted extraction (MAE) has several advantages over conventional extraction methods because its selective heating increases the effectiveness of the extraction process. The effect of different variables such as irradiation power, contact time and solid to solvent ratio was investigated. After extraction, regenerated spent bleaching earth (RSBE) is used in the bleaching of palm oil with activated bleaching earth (ABE) as a comparison. From this study it can be concluded that MAE can be used in the regeneration of SBE with hexane as solvent. The best conditions for each variable were an extraction time of 40 minutes, a solid to liquid ratio of 1: 4 and a microwave power of 450 W. Using RSBE, the highest yield obtained was 18.63%. Thus, RSBE can be reused in the bleaching process. However, to obtain the same quality results as treated using ABE, more RSBE is needed.