Long-Chain Alcohol-Modified Micellar Systems and Their Application in a Continuous Extraction Process

Abstract

The integration of an in situ extraction into biocatalytic processes is often limited by the toxicity of organic solvents. Therefore, it is desirable to use water-based extraction systems (for example, aqueous micellar two-phase systems). They can be used, for instance, for the extraction of valuable products from microalgae cultures. Recently, the nonionic surfactant ROKAnol NL5 was identified as a suitable surfactant for this purpose, since it forms an upper micellar phase, enabling an easy separation of whole-cell biocatalysts. However, its application at temperatures below 45 °C is limited by unstable phase boundaries, whereas the maximal temperature to ensure the vitality of the most microalgae cultures is ∼40 °C. To overcome this problem, the addition of long-chain alcohols to the surfactant–water mixture during extraction is suggested in this work. Using 1-hexanol, a continuous extraction process with the model solute trans-cinnamic acid at 40 °C in a stirred column could be realized. The results of a new suggested water/ROKAnol NL5/1-hexanol system at 40 °C (extraction yield, Y cont = 97.67% ± 0.14%; enrichment factor, log10 T CA = 2.42 ± 0.03; number of theoretical stages, N theo = 4.45 ± 0.16) are comparable to those of the water/ROKAnol NL5 system at 45 °C (Y cont = 99.26% ± 0.24%, log10 T CA = 2.60 ± 0.10, N theo = 5.88 ± 0.67), ensuring, however, no damage of microalgae.

Process design of a continuous biotransformation with in situ product removal by cloud point extraction

“…[ 26–28 ] It is important to consider that all components added to the systems, like salts, organics, or reactants, influence the phase equilibria and change the CPT, shifting the operation window of the extraction significantly. [ 7,29,30 ] Considering all these aspects, in this work APTMS is chosen as a medium for the extraction.…”