Violaine Athès

In this study, the technology of membrane contactors was assessed for the liquid–liquid extraction of highly valuable oxygenated terpenes from lemon essential oil using mixtures of water and ethanol as solvents (20–66% v/v ethanol). The main expected benefit of using membrane contactors in this application was the elimination of the phase separation step, which can be difficult in these types of systems, which are characterized by a low interfacial tension and the presence of natural surfactants. A commercially available polypropylene hollow fibre contactor (Liqui‐Cel^® 2.5 × 8 with X30 fibres) was used in this study. Stabilizing the interface between the hydro‐alcoholic solvent and lemon essential oil in membrane pores proved difficult (breakthrough pressure below 0.2 bar), even with solvents containing only 20% v/v ethanol. This problem was probably due to defects in the membrane material such as the presence of large pores (up to 4 µm in diameter). Nonetheless, the hydro‐alcoholic extract remained emulsion free throughout extraction, considered to be an improvement since it eliminated the time‐consuming decantation step (process intensification). High mass transfer coefficients up to 1.08 × 10⁻⁶ m/s were obtained for the tracer of oxygenated terpenes and a solvent with 66% v/v ethanol. The membrane never represented more than 25% of the total resistance to mass transfer. We demonstrated the high potential of using membrane contactors for this application, provided that improvements were performed on membrane materials. Copyright © 2011 John Wiley & Sons, Ltd.