|Title:||Development of an in situ extraction process of fatty acids from microalgae cultures||Language:||English||Authors:||Glembin, Philipp||Issue Date:||2018||Examination Date:||13-Jan-2017||Abstract (english):||
In this work micellar extraction was investigated in order to develop an alternative process for the in situ extraction of hydrophobic substances from microalgae cultures. The main requirements for an in situ extraction process such as biocompatibility, phase separation behavior and partitioning of the hydrophobic target substance between micellar- and aqueous phases were studied for a number of surfactants. The cloud point temperatures (CPT) as well as the biocompatibility of the nonionic surfactants with the microalgae C. reinhardtii, C. vulgaris, and S. obliquus was determined as a function of time. It was shown that algae cells are concentrated in the aqueous phase, whereas the hydrophobic compounds (fatty acids) are enriched in the micellar phase. Significant differences in growth and the photosynthetic activity of different algae strains after exposure to surfactants were determined. Thus, besides extraction, surfactants might be applied to control the growth of certain algae enabling the monoalgal culturing in outdoor cultivation of microalgae since the growth of the less surfactant-tolerant microalgae could be suppressed. For the most biocompatible surfactant under study, Triton X-114 with a biocompatibility of 98%, the kinetics of phase separation in the temperature range between 30 and 40°C have been investigated. The fastest phase separation took place at a Triton X-114 concentration of 3%wt at 40°C. The partitioning of representative hydrophobic substances between the both phases was predicted using the model COSMO-RS, the results were compared to experimental data with satisfying agreement (LogPcalc. palmitic acid: 0.82; LogPexp. palmitic acid: 0.75). Based on these results the extraction of valuable compounds from the microalgae Scenedesmus obliquus was realized on a pilot plant and compared to the lab scale experiments. Overall, the results indicate that a continuous micellar extraction with nonionic surfactants offers the opportunity for an in situ extraction of hydrophobic substances directly from the culture medium and is a promising alternative to a classic solvent extraction of dried algal biomass.
|URI:||http://tubdok.tub.tuhh.de/handle/11420/1508||DOI:||10.15480/882.1505||Institute:||Thermische Verfahrenstechnik V-8||Document Type:||Thesis||Thesis Type:||Doctoral Thesis||Advisor:||Smirnova, Irina||Referee:||Kuchta, Kerstin||License:||In Copyright|
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