Ingénierie de la surface des bulles pour la récolte des microalgues par flottation à l'aide d'une approche biophysique

Le résumé fourni par la source

Assisted flotation represents a promising harvesting technique that consists in air dispersed into microbubbles rising through a microalgae suspension. As a result, microalgae cells get attached to bubbles and are carried out and accumulated on the surface, without being damaged. Flotation is thus a relatively rapid operation that needs low space, has moderate operational costs, and that could thus overcome the bottleneck of feasible microalgal biofuel production. To make this technique more efficient for harvesting microalgae, the original proposed strategy relies on functionalizing the bubbles produced during the process with adhesive compounds, allowing bubbles to effectively capture the cells during their ascent. This requires (i) developing methods where microsize is produced bubble and their interaction with individual cells are modulated. Then (ii) determining which molecules are present on the surface of microalgae to identify a molecule that adheres to them. In order to identify which molecule could adhere to microalgae cells, we first analyzed the composition of their wall using a combination of techniques such as liquid chromatography and X-ray photoelectron spectroscopy (XPS). The information obtained from these analyses revealed the presence of chitin-like molecule such as chitosan on the cell surface. Then in a second step we (iii) determine whether the identified molecule effectively allows adherence to cells, for that at the molecular level the interactions between chitosan and the cell wall were measured using atomic force microscopy (AFM). After understanding the molecular basis of these interactions we then (iv) chemically modify this molecule to make it amphiphilic to functionalize the bubble surface. Basically, we added an hydrophobic group to hydrophilic chitosan through N-alkylation by reductive amination. Finally, we evaluate the possibility to functionalize the bubble and modulate its interaction with cells we have in a fourth step v) we evaluate the interaction between the functionalized bubbles and cells, and optimize an efficient functionalized bubble flotation process at microalgae population scale. The results of this project, by proposing a new efficient harvesting technique, will allow to exploit the full potential of microalgae biomass for the production of third generation biofuels and thus to limit the environmental impact of human activity.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.