Selective Extraction of Medium-Chain Carboxylic Acids by Electrodialysis and Phase Separation

Paula Andrea Hernandez, Miaomiao Zhou, Igor Vassilev, Stefano Freguia, Yang Zhang, Jürg Keller, Pablo Ledezma, Bernardino Virdis

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Abstract

Carboxylic acids obtained via the microbial electrochemical conversion of waste gases containing carbon dioxide (i.e., microbial electrosynthesis) can be used in lieu of nonrenewable building-block chemicals in the manufacture of a variety of products. When targeting valuable medium-chain carboxylic acids such as caproic acid, electricity-driven fermentations can be limited by the accumulation of fermentation products in the culturing media, often resulting in low volumetric productivities and titers due to direct toxicity or inhibition of the biocatalyst. In this study, we tested the effectiveness of a simple electrodialysis system in upconcentrating carboxylic acids from a model solution mimicking the effluent of a microbial electrochemical system producing short- and medium-chain carboxylic acids. Under batch extraction conditions, the electrodialysis scheme enabled the recovery of 60% (mol mol-1) of the total carboxylic acids present in the model fermentation broth. The particular arrangement of conventional monopolar ion exchange membranes and hydraulic recirculation loops allowed the progressive acidification of the extraction solution, enabling phase separation of caproic acid as an immiscible oil with 76% purity.

Original languageEnglish
Pages (from-to)7841-7850
Number of pages10
JournalACS Omega
Volume6
Issue number11
DOIs
Publication statusPublished - 2021
Publication typeA1 Journal article-refereed

Publication forum classification

  • Publication forum level 1

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

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