Oral Presentation International Solvent Extraction Conference 2025

Electrochemically Switching between extraction and back extraction of Lactic Acid (121593)

Kim W.J. Zijderveld 1 , Bastian Mei 2 , Guido Mul 1 , Boelo Schuur 1
  1. University of Twente, Enschede, NOT US OR CANADA, Netherlands
  2. Lehrstuhl für Technische Chemie, Ruhr-Uni Bochum, Bochum, Not US or Canada, Netherlands

During the purification of lactic acid, which follows the production by fermentation, an equal amount of gypsum is produced besides the desired lactic acid [1]. Furthermore, regeneration involves back-extraction [2] and during the purification of the lactic acid from the aqueous back-extract phase, the water from that phase is evaporated. To potentially reduce both the amount of gypsum formed and limit the energy needed for water evaporation, reactive extraction may be applied with switchable systems. Such switchable reactive solvent systems are solvents that exhibit good extraction capacity through interaction between the extractant and the solute[3]. When switched to a state which has a much lower affinity for the solute, in this case lactic acid, achieving a higher concentration in the back-extract phase may be realized. In our investigations, we studied redox-responsive solvents that can switch between an oxidized state and a reduced state. In an earlier phase of our studies we found a clear difference in the distribution coefficient when the solvent was applied in oxidized state or when applied in the reduced state, indicating the potential for an electrochemical trigger to enhance the difference in the distribution coefficient between the extraction and back-extraction stages in the process. In the study we present here, we investigated on the electrochemical switching of the solvent, and show the cyclic voltammetry behavior of the solvent and also in presence of lactic acid, which indicates the switching is reversible and that altering the solvent electrochemically to affect the distribution coefficient of lactic acid seems a viable approach. 

  1. [1] A. N. Marchesan, J. Felipe, L. Silva, R. M. Filho, M. Regina, and W. Maciel, “Techno-Economic Analysis of Alternative Designs for Low-pH Lactic Acid Production,” 2021, doi: 10.1021/acssuschemeng.1c03447.
  2. [2] L. M. J. Sprakel and B. Schuur, “Solvent developments for liquid-liquid extraction of carboxylic acids in perspective,” Sep Purif Technol, vol. 211, pp. 935–957, Mar. 2019, doi: 10.1016/J.SEPPUR.2018.10.023.
  3. [3] L. M. J. Sprakel, A. F. M. Holtkamp, R. Bassa, and B. Schuur, “Swing processes for solvent regeneration in liquid-liquid extraction of succinic acid,” Chemical Engineering and Processing - Process Intensification, vol. 143, p. 107600, Sep. 2019, doi: 10.1016/J.CEP.2019.107600.
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