Membrane contactors-assisted liquid-liquid extraction of biomolecules from biorefinery liquid streams: A case study on organic acids

The use of membrane contactors (MC) for the recovery of biomolecules in biorefinery processes has become increasingly popular thanks to their desirable properties such as robustness, large surface area, modularity and flexibility, as well as their non-dispersive nature. This review article provides a recent comprehensive and critical look into the recent progress made in the application of MC for the recovery of biomolecules such as aroma compounds (acetophenone, 2-phenylethanol, etc.), butanol, antibiotics, and organic acids from aqueous media and fermentation broths. Although some previous reviews have discussed the design and operation of membrane contactors for applications such as dissolved gases management and CO2 capture, this review focuses on the liquid-liquid extraction of biomolecules from biorefinery liquid streams. It includes a detailed discussion of the technical characteristics of MC and their applications for liquid-liquid extraction of organic molecules from bioconversion and liquid media. A focus is then put on the use of MC for the extraction of organic acids, looking at the effects of operating conditions, extracting phase, and feed phase on the extraction process, as well as proposing back-extraction of organic acids by MC. Some of the challenges and limitations currently associated with these applications are highlighted.