Thesis defense: Adithya Raveendran Thottathil
This thesis was aimed to explore the development of a lignin-first biomass fractionation strategy that uses green solvents and can be flexible in the choice of feedstock used and the outputs produced. To this end, five locally sourced biomasses were selected (camelina, miscanthus, 3 maize hybrids) to ensure an inter- and intraspecies diversity to create a flexible process that valorizes multiple feedstocks.
Miscanthus was selected as a reference feedstock based on the structural characterization of the cell wall residue and the extractability of the lignins. The reference feedstock was used with green solvents such as lactic acid (LA), 1,3 propanediol (PDO) and tetrahydrofurfuryl alcohol (THFA) to isolate lignins and study. Based on the results and the potential for diversification, LA was chosen as the solvent for indepth study.
Temperature, time and acid catalyst concentrations were identified as key triggers for appreciable biomass fractionation. The potential for esterification of LA into lignin substructures were confirmed based on experiments using model dimers and LA treatment of dioxane-lignin.
The results were used to create an empirical combined severity (CS) factor to relate the process parameters and the output lignin properties, creating a structure-property relationship. The CS factor was validated using new data points. The transferability of this CS factor to another biomass (maize Volney) confirmed that the trend observed in miscanthus could be replicated with maize.
The potential application of the isolated lignins were evaluated using DPPH assay and UV absorbance measurements. The results showed a correlation between the EC50 of the lignins and the phenolic OH content.
Director: Stéphanie Baumberger, "Lignocellulosic Biopolymers: from Cell Wall Assemblies to Synthons for Green Chemistry" APSYNTH team, INRAE, IJPB, Versailles
Co-direction: Betty Cottyn et Florian Pion, "Lignocellulosic Biopolymers: from Cell Wall Assemblies to Synthons for Green Chemistry" APSYNTH team, INRAE, IJPB, Versailles
Jury members
> Nicolas Brosse (Rapporteur) - Université de Lorraine, LERMaB, Vandœuvre lès Nancy
> Maud Villain-Gambier (Rapportrice) - Université de Strasbourg, IPHC, Strasbourg
> Brigitte Rousseau (Examinatrice) - Sorbonne Université, IPCM, Paris
> Carlos Ariel Cardona Alzate (Examinateur) - Universitad National de Colombia, Manizales
> Heman Höfte (Examinateur) - INRAE, IJPB, Versailles
Research developed at the Institute Jean-Pierre Bourgin for Plant Sciences.
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