Permeable Membranes PUR/TETA and PUR/TEPA for CO2 Capture Prepared with One-Step Electrospinning Technology

Abstract

A simple one-step technology of wire electrospinning is presented for the manufacturing of air-permeable CO2-capturing membranes, easily transferable to industrial production lines. The design of the chemically-modified polyurethane nanofiber membranes for CO2 capture was based on a combination of molecular modeling and technological experiments using one-step electrospinning (i.e., a modifying agent dissolved directly in a spinning solution). Polyurethane (PUR Larithane), chemically modified by TETA/TEPA amines, was used in the present study for the membrane design. Special attention was paid to two key parameters significant for the design of the functional unit, i.e., the CO2 sorption capacity and air permeability which depended on the amine concentration. The optimal combination of these parameters was found for the PUR/TEPA membrane (5 wt.% of TEPA in spinning solution): the sorption capacity was 13.97 cm3/g with an air permeability of 0.020 m/s. Molecular modeling proved to be a valuable tool that helped to clarify, at the molecular level, the structure of chemically-modified nanofibrous membranes.

Effect of wire and needle spinning on the direct manufacturing PAN/amine nanofibrous membranes for CO2 sorption

“…In this case, the amines on the surface interact strongly as found by molecular modelling in our previous work. 55 The air permeability for wire spinning is many times higher than for needle spinning at the same values of sorption capacity (see Tables 2 and 3). For example, when comparing unmodified samples, an average air permeability value of 19.8 L/m 2 /s was measured for wire spinning, while only 3.17 L/m 2 /s for needle spinning.…”

“…These sticking of amine modified nanofibers has been observed and confirmed by molecular modeling in work. 55 Sticking the fibers together creates bundles and generally leads to higher air permeability of the membranes, as shown by the HRSEM image in Figure 11. This is caused probably due to the fact that, with the same density of fibers in the layer, by sticking the fibers together, larger pores are created between the individual bundles of fibers compared to the dense entanglement of individual fibers, which are not bonded without the presence of amine.…”