| Abstrakt: |
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, Ycont= 97.67% ± 0.14%; enrichment factor, log10TCA= 2.42 ± 0.03; number of theoretical stages, Ntheo= 4.45 ± 0.16) are comparable to those of the water/ROKAnol NL5 system at 45 °C (Ycont= 99.26% ± 0.24%, log10TCA= 2.60 ± 0.10, Ntheo= 5.88 ± 0.67), ensuring, however, no damage of microalgae. |
