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

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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 nonconventional media, whereas the OTRs of a novel class of solvents, deep eutectic solvents (DESs), have not been determined yet. In this letter, we report for the first time on the OTRs of diverse DESs such as choline chloride:ethylene glycol (DES1, ChCl:EG), ethylammonium chloride:ethylene glycol (DES2, EAC:EG), choline chloride:glycerol (DES3, ChCl:Gly), lidocaine:oleic acid (DES4, LID:OA), and choline chloride:levulinic acid (DES5, ChCl:LA) while using water as a reference. In addition, we evaluated the effects of different molar ratios of ChCl to Gly (1:2, 1:4, and 1:9) for DES3 and addition of external water (up to 30% (v/v)) to DES1 (ChCl:EG (1:2)) on dynamic viscosity (I), dynamic water activity (aw), and volumetric mass transfer coefficient (kLa). We applied the dynamic method for OTR measurements and found up to 11-fold lower kLa values for DES1 (ChCl:EG (1:2)) and 6-fold lower kLa values for DES2 (EAC:EG (1:1.5)) than in water at 25 °C. With the addition of water at 30% (v/v) to DES1 (ChCl:EG (1:2)), the kLa value increased 3 times at 25 °C. While changing the molar ratio of Gly for DES3 from 1:2 to 1:9, the increase in viscosity was found to be 64%. Furthermore, we investigated the effect temperature (35 and 45 °C) has on the kLa values for those DESs and DES-water mixtures.

TidsskriftACS Sustainable Chemistry & Engineering
Sider (fra-til)8347–8353
Antal sider7
StatusUdgivet - jun. 2021

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