Supercritical CO2 permeation through dense commercial polymeric membranes: Permeability measurements and influence of pressure.

Abstract

In the food industry, supercritical CO2 (sc-CO2) is widely used as an extraction solvent, particularly for the extraction of lipids from seeds. After the extraction, the decompression is usually used to recover the products. Afterwards, the recompression for CO2 recycling is highly energy consuming and this handicaps industrial development when medium to low added-value post-extraction products are considered. Recovery of solutes using membrane technology is an interesting alternative for the regeneration of CO2 loaded with oil. The suitable membrane must have a high permeability towards CO2 as reasonable filtration area is needed. In this work, we have studied the CO2 membrane permeability of two different dense polymeric membranes, AG aromatic polyamide reverse osmosis membrane and PuraMem™ silicone nanofiltration membrane. It was considered that the pure sc-CO2 permeation is governed by the solution-diffusion model, which explain the observed permeability changes as a function of CO2 viscosity and fugacity (i.e. pressure) and the polymer properties as chemical composition and structure.Indeed, it was observed that the permeability increased with pressure to reach a maximum value at a permeate pressure of 180 bar (17.3 ± 0.9 kg/(h.m2.bar)), and then decreased in the case of a crosslinked polymer (AG membrane). While, for a slightly crosslinked polymer (PuraMem™ membrane), the permeability was found much higher and it is about 751.6 ± 26.4 kg/(h.m2.bar) at a permeate pressure of 160 bar.