Extraction of free fatty acids from soybean oil using ionic liquids or poly(ethyleneglycol)s

The alternative solvents poly(ethyleneglycol)s (PEGs) with various molar masses and room temperature ionic liquids (RTILs) AMMOENG100 and 1‐butyl‐3‐methylimidazolium dicyanamide (bmimDCA) were studied for the purpose of extraction of linoleic acid from soybean oil. Liquid‐liquid phase equilibrium was measured for binary (PEG + soybean oil), (RTIL + soybean oil) as well as ternary (PEG + soybean oil + linoleic acid), (RTIL + soybean oil + linoleic acid) mixtures, as a function of temperature and composition. The influence on distribution coefficients and separation factor of temperature, initial acid content of the oil and solvent to oil ratio were studied. The effect of molar mass in the case of the PEGs was also examined. The experimental results were modeled using the Peng‐Robinson cubic equation of state coupled with the Mathias‐Klotz‐Prausnitz mixing rule, with good results. © 2010 American Institute of Chemical Engineers AIChE J, 2011