Extraction of peanut oil in a fixed bed column using alternative solvents

Peanut (Arachis hypogaea) is an oil-rich-herbaceous plant widely cultivated in the São Paulo state mainly to renovate the sugarcane soil. Its oil is usually obtained by cold-pressing; however, it can be extracted by solvents. Although all troubles and dangers related to hexane, it still being the main solvent used in the industry. Nowadays, the oil extraction yields using short-chain alcohols as ethanol and isopropanol are being evaluated as alternative solvents. Besides those solvents has low toxicity and are renewable, they can be also used for the biodiesel production. Therefore, the oil extraction using a solvent produced in the ethanol power plant, associated to the biodiesel production using the same solvent, can be interesting for supplying the trucks fleets, contributing for less greenhouse gas emissions. Ethanol and isopropanol were used as solvents to extract the peanut oil in a fixed bed column at 70 °C with extract recirculation during 4 h. Both crude and toasted peanut were used as grounded raw materials, being composed of 46% and 48% oil, and 5.0% and 3.5% water, respectively. Higher oil content in the extract was obtained using isopropanol (34 – 36%) than for ethanol (18 – 26%). The extract retention in the solid was slightly lower for isopropanol than for ethanol, and for toasted peanut than for the crude one. The addition of up 50% isopropanol into ethanol increased the solvent solubility in oil, improving the extraction yield.