Residual oil recovery using bio-ethanol from spent bleaching clay and its characterization

Residual oil from oil palm refining waste, spent bleaching clay (SBC) was recovered through a pilot plant scale up solvent extraction process. To develop a green extraction and sustainable approach for recovery of oil, bio-ethanol was used as a solvent instead of hexane. The SBC was extracted in a round-bottomed jacketed vessel subjected to heat and two different pressures. Two consecutive separation processes was applied in this study, fractional crystallization followed by evaporation. The yields of residual oils extracted slightly under vacuum pressure were higher by 64% than those from the extraction at atmospheric pressure. The residual oil recovered by evaporation exhibited inferior qualities in term of free fatty acid (FFA). In contrast, the oil recovered by fractional crystallization shows superior FFA content to that of crude palm oil (CPO) which was suitable for food applications.