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Renson_72081400_2022.pdf
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- It is undeniable that human activities have a direct impact on global warming. Indeed, since the industrial period, the concentration of CO$_2$ in the atmosphere has constantly increased. In order to limit global warming, a reduction in CO2 emissions is necessary. To achieve this, new capture and storage techniques have been developed. The most widely used technology is chemical absorption using amine-based solvents such as monoethanolamine (MEA). However, this technique has drawbacks such as a high energy demand to regenerate the solvent or its environmental impact. Therefore, alternative post-combustion CO2 capture technologies are being studied. The use of a gas-liquid membrane contactor is an interesting solution to replace a conventional absorption column. Aqueous carbonate solutions promoted by enzymes are possible substitutes for solvent amines. The aim of this thesis is to fabricate a biocatalytic composite membrane for use in a gas-liquid membrane contactor where absorption is carried out in a carbonate solution. For this purpose, a PVDF membrane support is modified by adding a layer of poly(ionic liquid)s where enzymes are immobilized. Several parameters of this poly(ionic liquid) layer were studied, such as the concentration of ionic liquid monomer or the concentration of cross-linker, in order to determine the optimal composition. Then, the immobilization protocol of the enzymes was also optimized. Once the membrane was designed, it was tested in an absorption set-up to determine its mass transfer coefficient and its reusability. Although the addition of an extra layer on the PVDF membrane is a counter-intuitive method to improve the overall mass transfer coefficient, because it adds extra resistance, an increase in this coefficient has been observed. Indeed, the biocatalytic membrane, thanks to the immobilization of enzyme, improves this coefficient. Moreover, after several absorption cycles, the membrane showed a good reusability, as its overall mass transfer coefficient decreased only slightly.