Effects of Solvent Concentration on Refining (Degumming, Dewaxing, and Deacidification) of Canola Oil Using Membrane Filtration

Miscellas of canola were obtained by mixing its crude oil with hexane solvent at ۸۰:۲۰ and ۷۰:۳۰ ratios. Then, ۱۶.۱ M of phosphoric acid and ۶.۹۲ M of sodium hydroxide were mixed with the resulting micelles at ۰.۳% (w/w for degumming) and ۱۳% (w/w for neutralizing), respectively, before two sequential Membrane Filtrations (MF). The MF unit had a crossflow mode equipped with three independent variables of transmembrane pressures or TMP (at ۲, ۳, and ۴ bar), feed velocity (at ۰.۵ and ۱ m/s), and temperatures (at ۳۰, ۴۰, and ۵۰˚C) were used to determine the efficiencies of two MF processes and find out their optimum conditions. When the crude canola oil was mixed with ۲۰-۳۰% solvent and passed the two stages of MF (for degumming and refining) at TMP=۲ bar, feed velocity=۱ m/s, and temperature = ۵۰˚C, the final polished canola oil had < ۵% soap, < ۵% phosphorus, < ۵% fatty acids, and < ۱۵% wax. Membrane refining, compared to chemical refining, significantly reduced the phosphorus content (۵۰%), free fatty acids (۲۹%), soap (۹۹%), and wax (۷۲%) of refined canola oil. While the permeate flux of canola miscella with ۲۰% solvent increased with rising TMP, feed velocity, and temperature, the ones with ۳۰% solvent did not increase with a similar trend. The highest permeate flux of refined canola oil reached ۰.۰۳ Kg/m۲, s for miscella with ۲۰% solvent when the feed velocity, TMP, and temperature of degumming or neutralization were ۱m/s, ۳-۴bar, and ۳۰-۴۰oC, respectively. The dominant fouling changed from standard to cake blocking when the crude oil was mixed with ۲۰ or ۳۰% solvent, and the TMP of the MF process in each stage of degumming and neutralization was > ۲ bar.

کلیدواژه ها:

Canola oil ، Membrane ، Miscella ، Refining ، Microfiltration ، Polyvinylidene Fluoride