Removing CO₂ from Xenon anaesthesia circuits using an amino-acid ionic liquid solution in a membrane contactor

The noble gas xenon possesses many characteristics of an ideal anaesthetic agent. However, its application is limited in daily clinical routine due to its elevated price. The present work proposes the use of a gas-ionic liquid membrane contactor system in anaesthesia closed-circuits, for the removal of carbon dioxide, to allow the recycling of the anaesthetic agents, as a route to enable the widespread use of xenon. In this work, different anaesthetic gas delivery conditions were simulated and explored, considering the use of different anaesthetic gas mixtures. The results obtained, using a cholinium lysinate ionic liquid solution as CO₂ absorbent, expressed high efficiency, especially when xenon was used as the inhalational anaesthetic, leading to an overall CO₂ mass transfer of 1.26 × 10⁻⁵ m.s⁻¹. The ability of the proposed system to recover xenon allows to reduce drastically the cost per operation, which can be a step forward for the routine use of this gas on surgeries. Additionally, this work evaluates the use of thermal and chemical regeneration of the ionic liquid solution. It was found that the thermal regeneration approach was not adequate for the regeneration of the IL. On the other hand, the use of ion-exchange resins proved to be an efficient and simple strategy for IL regeneration, allowing for an easy integration in the proposed system. This study opens a new direction not yet explored that may lead to more efficient IL regeneration processes.