Solvent recovery from vegetable oil miscella by novel solvent-resistant nanofiltration membranes

Vegetable oil is commonly extracted from oil seeds using hexane. Separation of oil and solvent (hexane) from this extracted mixture (known as miscella) is usually carried out by solvent evaporation or distillation. Solvent recovery from miscella consumes about 50% of the total energy required for the edible oil production. Solvent evaporation is an energy intensive operation and explosive vapors in the vegetable oil plant also increase a safety problem. These limitations can be significantly overcome by employing nanofiltration membranes for separation of oil and solvent. However, the solvent stable-nanofiltration membranes that were available generally had low solvent flux and/or poor separation characteristics and long-term stability. Hydrocarbon-based and Polydimethylsiloxane-based nanofiltration membranes swell in organic solvents, leading to drastic performance loss. Therefore, there exists a need for solvent-resistant nanofiltration membranes available on a commercial scale with superior solvent flux and oil retention for recovery of solvent from miscella. If successful, this project will provide a highly energy-efficient technology for pre-concentration of vegetable oil miscella. Development of this technology will simultaneously address the issues of safety and hazardous solvent emissions that are encountered in the vegetable oil processing industry.