Solvent Recovery from Vegetable Oil Miscella by Novel Solvent-Resistant Nanofiltration Membranes

Soybean is the major source for production of edible oils worldwide and in United States. Pressing of the soybean into flakes followed by the solvent extraction with hexane (solvent) is most widely practiced for extraction of oil. Separation of solvent from oil-solvent mixture for solvent recovery and reuse is usually carried out by solvent evaporation. Evaporation (or distillation) demands considerable amount of energy and associated costs since it involves an energy and capital intensive phase change of the solvent. Solvent used for oil extraction (i.e. hexane) from oil seeds is highly volatile, flammable, and is also explosive; therefore, solvent recovery by distillation is also a physical hazard. Hexane is also categorized by the EPA as hazardous air pollutant and the inevitable loss of hexane vapors into the environment during the solvent recovery by distillation is a severe environmental issue. Based on our experience with chemically resistant membranes, Compact Membrane Systems (CMS) has proposed and demonstrated the feasibility of superior membrane filtration technology for separation of solvent from vegetable oil-solvent mixture. Benefits of developing this superior membrane filtration technology are associated with (i) energy and capital savings by replacing the conventional technologies such as evaporation, (ii) increased process safety, and (iii) reduced solvent emissions into the environment from vegetable oil processing plants. The proposed membrane filtration technology will have a significant impact in many of the industrial processes using distillation/evaporation. For example, solvent recovery by the superior membrane filtration technology will be of great value in processing other oil seeds such as corn, cotton seed and canola. Other applications of the proposed membrane filtration technology include solvent recovery from algae oil extraction process in biofuel production and solvent recovery from solvent-deasphalting process in petroleum refining.