Modification of polymeric hollow fibers by microfluidics for gas separation

Abstract

The majority of the current energy is produced from burning fossil fuels, being it electricity, fuel or gas. Without a doubt these processes result in the emission of carbon dioxide to the atmosphere. CO2 holds a major share in causing dramatic climate changes and its impact can now be seen on the world panorama. Gas streams focused on the separation of CO2 from CH4 is one of the possible remediation technologies, especially important for the gas industry. Membranes can provide an eco-friendly and low energy consumption alternative to traditional separation techniques. Various membranes with different structures have been studied for this purpose and thin film composite (TFC) membranes being especially attractive due to their high performance thanks to their small thicknesses (ca. 50 nm) and possibility of modification with porous nanoparticles (e.g. metal-organic frameworks (MOF)). In general, the structure of these membranes, usually prepared by interfacial polymerization, enables that the chemistry and porosity of both layers are changed separately. In this work, we focused on synthesizing a continues MOF layer on the lumen side of the hollow fibre instead of MOF being dispersed in the polymeric matrix. Gas separation with MOF based thin-film nanocomposite membranes represent a unique opportunity to produce a technology breakthrough able to address the environmental tasks just mentioned. Until now the fabrication of these membranes has been mainly demonstrated with a single hollow fiber (HF) [1,2]. Thus, another goal of this work is the implementation of the microfluidic synthesis methodology at larger scale and to increase the number of HF membranes that can be modified simultaneously of up to 10. Briefly, the synthesis procedure involves using three syringe pumps and pumping of first: metal salt, second: ligand, and third: methanol to the inner side of the polysulfone hollow fiber. The fabricated containing a thin selective MOF layer mini-modules are tested in a gas separation set-up provided of gas chromatograph for the estimation of the membrane performance.