Membrane-based solvent extraction of vanillin in hollow fiber contactors

The goal of this research is to evaluate the potential of using membrane based solvent extraction for the recovery of vanillin obtained by bioconversion of ferulic acid in view of the on-line extraction from the bioconversion broth, thus coupling bioconversion and separation. The partition coefficients of vanillin and ferulic acid in various solvents were measured. Good properties were shown by ethyl and n -butyl acetate: at pH 7 these solvents showed high affinity for vanillin and low affinity for ferulic acid. At high pH, on the contrary, vanillin is more soluble in water than in the solvent, thus making possible the counter-extraction of vanillin from the solvent used in the extraction. Extraction and counter-extraction experiments were performed by hollow fibre modules, the feed flowed either through the lumen or in the shell side. The overall mass transfer coefficients were calculated from the data and compared with theoretical values.

A C D di do dlm E Eff k Kw m R S V W membrane area concentration diffusion coefficient inner diameter outer diameter log mean diameter mS/W, extraction factor efficiency, Eq. (1) mass transfer coefficient overall mass transfer coefficient partition coefficient mVS/Vw solvent flow rate volume feed flow rate The membrane based, dispersion-free, solvent extraction is a suitable technique to recovery vanillin from dilute aqueous solutions. Coupling an MC to the bioreactor for in-situ Greeks o porosity t tortuosity factor Subscripts and superscripts e exit m membrane S organic phase w aqueous phase initial value