Membrane technology for vegetable oil processing—Current status and future prospects.

Vegetable oil processing has been identified as one of the potential nonaqueous
applications of membrane technology. Membrane-based processing has been
largely attempted on individual steps of the conventional refining process with
reasonable success. With the advent of organic-solvent-nanofiltration, membrane
desolventizing of hexane oil miscella has received greater attention, revitalizing
the prospects of integrated membrane processing. A practical evaluation
of membrane augmented desolventizing revealed that approximately 65% energy
savings towards solvent evaporation could be achieved in an industrial environment.
Further, a pragmatic appraisal advocated that an integrated membrane
process with a focus on pretreatment and desolventizing along with physical
refining would be a desirable approach for fortifying the benefits. The present
review intends to channelize the efforts to overcome the current limitations and
highlights the importance of developing better membranes, process evaluation
under appropriate practical conditions, and developing suitable cleaning protocols
for stable performance. In the case of alternate solvents to hexane, membrane
solvent recoverywould be a favorable approach to overcome the limitation
of associated higher thermal energy requirements. Nevertheless, solvent selection
should be based on a composite evaluation of extraction andmembrane desolventizing,
specific to the type of oil. Finally, a comprehensive process scheme
has been proposed to realize the benefits in extraction-refining plants. In this
direction, a few pilot demonstration plants need to be established and operated
for 1–2 years to understand and overcome the practical difficulties and limitations
of the technology, leading to its industrial adoption.