Further Improvements in Lactic Acid Membrane Extraction: Introducing Deep Eutectic Solvents for an Emulsion-free, Non-toxic Direct Extraction

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Description

Introduction: Lactic acid (LA) is a carboxylic acid with extensive applications in industries such as food, cosmetics and pharmaceuticals, driven in particular by the demand for polylactic acid [1,2]. LA is mainly produced by fermentation (over 90% worldwide) and significant research has been done in recent years to find disruptive ways to improve the production process of LA [3,4]. It is reported, that both capturing and purification of LA from fermentation works with the use of liquid-liquid extraction [5]. However, the formation of stable emulsions and the toxicity of solvents are drawbacks of this downstream processing technology. Membrane extraction (ME) prevents from emulsion formation and reduces the impact of solvents to the fermentation broth [5]. Using <green solvents= based on deep eutectic systems, the impact of the solvent can be further reduced and triggers the attraction of liquid-liquid extraction as technology for the direct extraction of carboxylic acids in general and LA in particular.
Experimental/methodology: This work evaluates the performance of LA ME from several LA sources using a preliminary studied solvent based on tri-octylamine and decanol [5], and a green solvent alternative based on a thymol-menthol deep eutectic solvent (DES) [6]. The design of experiments and optimization lead to systematically identified operating conditions (in terms of solvent composition and temperature) that improve the performance of LA membrane extraction. The membrane area required to apply the ME technology for in situ LA ME is calculated from the performance evaluation of the two solvent systems, TOA/decanol and TOA/DES.
Results and discussion: Optimized conditions for LA ME were identified with 10 wt% TOA in the DES (60 mol% thymol and 40 mol% menthol) at an operating temperature of 50 °C. The overall mass transfer was obtained for both solvents and multiple sources of LA as shown in Figure 1. The green solvent showed a lower performance, resulting in a higher membrane area required for its application for in situ LA extraction. As for the ME of LA with TOA/decanol, also the use of TOA/DES as solvent did not result in any formation of emulsion and delivered clear LA containing extracts at any time.
Period10 Sept 2024
Event titleEuromembrane 2024
Event typeConference
LocationPrag, Czech RepublicShow on map