Mechanisms of transfer through organic solvent nanofiltration membranes: application to the fractionation of lipids and carotenoids from microalgae

Microalgae are characterized by relatively high contents of lipids and carotenoids, along with a wide diversity of these molecules. Their production from microalgae is environmentally friendly and relatively rapid. They can be used for food, cosmetic, dietary supplements and pharmaceutical because they exhibit antioxidant properties, could prevent chronic diseases such as cardiovascular disease, certain type of cancer, and promote eye health and immune function.

Carotenoids gather astaxanthin, fucoxanthine, β-carotene, lutein, zeaxanthin, etc. which are hydrophobic tetraterpenoids. Non-polar lipids of microalgae may include triglycerides, diacylglycerols, monoacylglycerols, fatty acid ethyl esters, free fatty acids, phosphatidylethanolamines, and other non-polar phospholipids. Thus, various structures, chemical compositions, molar mass, etc. of carotenoids and lipids can be found.

Rather than valorizing all the family of lipids and carotenoids as a single extract, it may be better to fractionate and isolate them, thereby increasing their added value. Less toxic “green” solvents compared to conventional organic solvent may be efficient to extract lipids/carotenoids from microalgae. Nevertheless, selectivity i.e. ability to extract preferentially one compound rather than another is often low whereas the purification and polishing requires highly selective yields to reach the targeted properties and concentrations. Moreover, in addition to carotenoids/lipids, others pigments such as chlorophyll are also extracted and have to be removed in view of purification. On the other hand, Organic Solvent-resistant Nanofiltration membranes (OSN) are now emerging for the purification of solutes between 200 and 1000 g.mol^-1, while reducing operating costs and times as well as separating at room temperature and without phase change. Thus, low-molecular-weight thermolabile compounds can be separated by OSN. Fractionation by size and electrostatic attributes can also be possible and allow isolation of carotenoids from complex matrices (presence of various compounds extracted during solvent extraction). Thus, “green” solvent extraction and OSN coupling could enhance the global selectivity and environmental impact since mechanisms of extraction of each process could complement each other.

The objective of the project is to study the transfer/transport mechanisms of carotenoids and non-polar lipids and solvents during environmentally friendly Organic Solvent Nanofiltration in order to improve selectivity and hydraulic performance.

In order to candidate : https://amethis.doctorat.org/amethis-client/prd/consulter

      Filter by thesis supervisor / MASSE Anthony

Location of the thesis: GEPEA laboratory

Supervisors: Anthony MASSE (GEPEA – Associated Professor Full),
                      Murielle RABILLER-BAUDRY (ISCR - Professor)

Skills:

• The candidate must have skills in Chemical Engineering Process
• Experience in mathematical modeling is required.
• Knowledge of analytical chemistry would be appreciated.
• Experience in microalgae cultivation would be appreciated.
• He/she must have a strong interest, both in experimental and theoretical research.
• The candidate will have to demonstrate rigour, autonomy and dynamism.