Extraction of Vanillin from Aqueous Matrices by Membrane-Based Supercritical Fluid Extraction: Effect of Operational Conditions on Its Performance

Supercritical fluid extraction, using a hollow fiber membrane contactor (HFMC), is an attractive and feasible process for the food industry due to the controlled contact between the phases and the safety that the membrane processes allow. This research aimed at the extraction of vanillin from an aqueous solution with supercritical carbon dioxide (SCCO2). The highest extraction percentage and permeate flux of the system were established through the evaluation of operational parameters. The extraction was developed using an HFMC under steady-state conditions and by varying the vanillin concentration (70–500 ppm), temperature (35–50 °C) and pressure of the system (75–140 bar), aqueous solution flow rates (0.1–0.5 mL min–1), and SCCO2 flowrates (50–80 mL min–1 in standard conditions).Experimental results showed the feasibility of extracting vanillin in one step, obtaining extraction percentages between 24.51 and 47.97%. Simultaneously, the mass transfer analysis of the HMFC by means of numerical simulation based on the theory of a resistance-in-series model depicted the negative effect of the temperature on the extraction capacity of this system. In an overall analysis and for the changes in the pressure and temperature of the system, it was possible to demonstrate that the phase equilibrium established at the aqueous–SCCO2 interface was determinant in the separation performance of this membrane contactor process.