Sorp-Vection-Based Membrane Silicone Oil Purification

"Sorp-vection" is a membrane separation technique that synergistically combines sorption with convective flow mechanisms. Beyond its conceptual discussion, we demonstrate a sorp-vection separation achieved in a gas-liquid system, where permeation of a gas directly drives selective permeation of an organic solute across a dense polymer layer overcoming osmotic limitations of conventional membrane processes. Here, a long-standing challenge in silicone oil production is addressed, in which residual cyclic oligosiloxanes are removed from silicone oil streams through permeation of CO₂ across an optimally crosslinked PDMS selective layer. A lab-scale 1^st generation Sorp-vection system demonstrated, with a separation factor above 15 to remove D4 (octamethylcyclotetrasiloxane) from low-concentration feeds using both lab-grade silicone oil (Sigma-Aldrich) and an industrial-grade feed (DOW-SFD). Good agreement was found with a predictive model based on liquid D4 and high-molecular-weight silicone oil sorption data in crosslinked PDMS. This proof-of-concept study introduces the sorp-vection strategy, expanding it from conventional two-component systems to a three-component configuration in which convective flow is introduced as an independent driving entity. Addressing concentration polarization in next-generation versions of the sorp-vection process is expected to ensure stable long-term performance and to establish sorp-vection as a transformative approach for industrial purification.