Development of integrated extraction-distillation apparatus for oil recovery from spent bleaching earth (SBE)

The increase of Crude Palm Oil (CPO) consumption in Indonesia has led to higher CPO production, where the refining CPO involves bleaching process to reduce the color of CPO and remove impurities, gums, and free fatty acids using bleaching earth. This process results in the accumulation of Spent Bleaching Earth (SBE) as primary waste which still contains around 20% vegetable oil. According to the Government Regulation No. 22 of 2021, SBE is excluded from the hazardous waste list if its oil content is below 3%. One of the methods to reduce the oil content in SBE is an extraction process using a solvent. In this work, a modified extraction-distillation apparatus was proposed by integrating extraction and solvent recovery into a single apparatus. This apparatus enables the simultaneous extraction of oil from SBE and the separation of recovered oil (R-Oil) and recovered solvent (R-Solvent). The solvents used in this study were technical n-hexane and condensate (C5+), with SBE mass-to-solvent volume ratio of 1:6 and 1:8. The initial oil content in the SBE was 16% based on analytical result. The extraction process was carried out over varying durations of 1, 2, 3, and 4 hours, yielding the highest oil content in R-Oil at 11.81% for n-hexane and 13.38% for condensate as solvents, both at a 1:8 ratio and 4 hours duration. The R-Solvent results from the apparatus over±4 hours distillation were found to be 70-86%, 59-72% for n-hexane and condensate solvents respectively. Subsequent analyses were conducted to identify components in the R-Solvent using Gas Chromatography and Mass Spectroscopy (GC-MS) which revealed no oil content in the R-Solvent for either n-hexane or condensate, and to measure oil content in de-Oiled Bleaching Earth (de-OBE) for the 4-hour extraction period which showed 2.9% and 2.7% for n-hexane, and 2.8% and 1.3% for condensate at ratios of 1:6 and 1:8 respectively, thus categorizing de-OBE as non-hazardous waste.