The development of biocatalytic flat sheet membranes containing ionic liquids for CO2 capture in gas-liquid membrane absorption

Details

Supervisors

Luis Alconero, Patricia

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil en chimie et science des matériaux, à finalité spécialisée

Abstract

The unquestionable link between human activities and global warming due to CO2 emissions has led to the development of novel CO2 capture strategies. Gas-liquid membrane absorption with the use of benign solvents promoted with the enzyme carbonic anhydrase (CA) try to meet this objective. Indeed, they present an encouraging alternative to the actual benchmark technology, gas-liquid absorption with amine-based solutions, whose energy penalty and significant environmental impact are non-negligible drawbacks in the actual context. The goal of this master’s thesis is to study and optimize the absorption performance of composite biocatalytic membranes in a gas-liquid membrane contactor. In this sense, PVDF membranes are modified with a thin poly(ionic liquid)s (PILs) film used to immobilize enzyme carbonic anhydrase by adsorption. However, the combined use of enzymes, PILs, and membranes is still a research topic under development. In this work, it is shown that the synergy between CA, PILs, and membranes can lead to an overall mass transfer coefficient of 12.24 m3/m2/s with the poly([VEIm][Br]) ionic liquid, three times higher than for PVDF. It was found that the optimization of the solvent concentration was important to promote the enzymatic activity. Higher liquid flow rate and gas flow rate using a fresh solvent were all yielding better results as they were beneficial for the mass transfer. In the next part of this work, three new anions (BF4-, NTf2, and acetate) were exchanged with Br– anion. They revealed that tuning the hydrophobicity/hydrophilicity of the immobilization support and membrane contactor material is a key feature for the success of an effective gas-liquid absorption. Naturally, hydrophobicity prevents membrane wetting, but hydrophilicity is favorable for enzyme immobilization. All these results are promising as they were enhancing gas-liquid absorption in membrane contactors. It is anticipated that this work will be the starting point of further studies aiming at developing more eco-friendly and economical alternatives for CO2 capture. As an example, many anions and cations are still available and could lead to better absorption results.