CO₂ removal from anaesthesia circuits using gas-ionic liquid membrane contactors

Nowadays, the reutilization of anaesthetic gases is accomplished by capturing carbon dioxide with soda lime, a solid adsorbent mostly composed by calcium and sodium hydroxide. To overcome the issues regarding the use of soda lime, this work proposes an alternative process to remove carbon dioxide through the use of a membrane contactor combined with a biocompatible ionic liquid (IL), cholinium lysinate, with high absorption capacity (5.9 mol_CO2/kg_IL). The carbon dioxide removal rate and IL solution regeneration, were assessed, varying the feed gas composition, relative humidity and ionic liquid flow rate conditions. Overall mass transfer coefficients and separation factors were determined. From the results obtained, the proposed system is feasible to remove carbon dioxide from anaesthetic gas circuits. Moreover, the system working operation time obtained was 63 h, which in a mass basis comparison with soda lime (current technology), is 3–5 times higher.