Biodiesel Purification using an Ion Exchange/Adsorbent Resin with Regeneration through Supercritical Fluids

The glycerol desorption from the ion exchange and adsorbent resin Purolite PD206 was studied using conventional and supercritical fluids techniques. Untreated biodiesel was purified by dry washing using the resin and, after purification, the glycerol desorption was carry out using three diferent solvents: absolute ethanol under atmospheric conditions at different mass flows (10 and 30 g/min), or supercritical CO2, or ethanol-modified supercritical CO2 (35:65 molar ratio of ethanol:CO2). In the supercritical runs the pressure was 14 MPA, temperature was 110 and 130°C, and mass flow rates were 10 and 30 g/min. Results have showed that ethanol is an efficient co-solvent for this resin regeneration. Desorption kinetics showed that it is possible to carry out the resin regeneration in just seven minutes using supercritical fluids, while using absolute ethanol under atmospheric conditions it is necessary around 210 minutes.