Sustainable recovery of pure natural vanillin from fermentation media in a single pervaporation step

Abstract

The recovery of vanillin from aqueous media by organophilic pervaporation is studied and optimised. Vanillin is recovered as a pure solid free of contaminants in a single pervaporation step. Due to the high-boiling point of this compound its transport across the pervaporation membrane is controlled by the desorption step at the downstream surface of the membrane. Under these circumstances, it is concluded that higher fluxes of vanillin may be achieved if the dense top layer of the composite membrane used in this process faces the downstream compartment. This procedure minimises the local drop of the partial pressure of vanillin at the downstream surface of the membrane, avoiding the formation of solid deposits of vanillin at the membrane. A low downstream pressure must be used in order to keep an appropriate driving force for transport. The use of organophilic pervaporation for the direct recovery of natural vanillin from post-fermentation media is demonstrated, at the temperature of fermentation in a solvent-free process, assuring the quantitative recovery of pure vanillin free of other media constituents.