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The overall goal of this program is to develop solvent resistant nanofiltration membranes with superior performance for pre-concentration of vegetable oil miscella. <P>
Membrane performance will be targeted for a solvent flux of 10-15 liters/m2-hr at a transmembrane pressure of 400 psi and volume concentration ratio (i.e. ratio of feed volume/retentate volume) of greater than or equal to 2.0. <P>
The hidden objective of this program is to develop a technology that is highly energy efficient compared with the conventional distillation. So, the economics of the developed technology will be compared with distillation.
NON-TECHNICAL SUMMARY: 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.
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APPROACH: This program involves development of solvent-resistant nanofiltration membranes and evaluation of these membranes for separation of solvent (hexane) from vegetable oil miscella. Nanofiltration membranes will be evaluated with Vegetable Miscella, prepared from 20% (w/v) commercial refined soybean oil, 5% oleic acid and 75% hexane. Deacidification (i.e removal of oleic acid) of the miscella will be simultaneously studied along with the recovery of hexane. A standard nanofiltration cell in a batch mode of operation at room temperature will be used for these studies. At the end, the membranes will be optimized for higher solvent flux and oil retention. Oil content in the feed, retentate and permeate solutions will be analyzed by gravimetry.