Comparison of microwave assisted extraction and ultrasound assisted extraction on recovery of residual palm oil from spent bleaching earth

Recovery of oil contained in spent bleaching earth (SBE) will have a good impact on the environment and economy. The process can be carried out using Microwave Assisted Extraction (MAE). This study aimed to determine best operation parameters for residual palm oil recovery using MAE and compare it to Ultrasound Assisted Extraction (UAE). The oil extraction was carried out using hexane as solvent at variable microwave power (100, 180, and 300 W), SBE to solvent ratio (1:4, 1:5, 1:6), and extraction time (50,70 and 80 min). The highest oil yield was achieved at microwave power of 300 W, SBE to solvent ratio of 1:5 and extraction time of 80 min at 20.97%. The main components of the oil produced were C16 (56.65 %wt) and C18.1 (28.35 %wt). The free fatty acid content, moisture, iodine value, deterioration of bleachability index (DOBI) and peroxide value of the resulting oil were 10.91%, 1.52%, 56.71 g I2/100 g, 1.372 and 7.419 meq/kg respectively.