Can Deep Eutectic Solvents Sustain Oxygen Dependent Bioprocesses? – Measurements of Oxygen Transfer Rates

The oxygen transfer rate (OTR) of dioxygen to solutions describing the transport of oxygen gas from the gaseous phase into the liquid phase of a reaction system over a given period is an important measure for biotechnological applications. The OTRs have already been described for aqueous systems and also recently for organic and non-conventional media, whereas the OTRs of a novel class of solvents, deep eutectic solvents (DESs), have not been determined yet. In this contribution, we report for the first time on the OTRs of choline chloride:ethylene glycol (ChCl:EG, ‘ethaline’) and ethylammonium chloride:ethylene glycol (EAC:EG, ‘ethethylaline’) while using water as a reference. We applied the dynamic measurement method and found up to 11-fold lower volumetric mass transfer coefficient (kLa) for ethaline and 6-fold lower for ethethylaline when compared to water at 25°C. Furthermore, we investigated the effect temperature (35°C and 45°C) has on the kLa for those solvents.