A systematic study on the effects of synthesis conditions of polyamide selective layer on the CO₂/N₂ separation of thin film composite polyamide membranes

Abstract

Different top layer fabrication methods (amine‐first, acid‐first, spin coating), organic phase solvents (hexane, heptane, mixed hexane/heptane), acid acceptors (triethylamine, sodium carbonate, sodium hydroxide), and surfactant sodium dodecyl sulfate concentrations (0, 0.05, and 0.1 wt%) were utilized to fabricate thin film composite polyamide membranes for CO2/N2 separation. The results, according to an L9 orthogonal array of Taguchi approach, showed that employing acid‐first method increases both CO2 permeance and CO2/N2 selectivity of the membranes at a feed gas pressure of 3 bars. On the other hand, sodium hydroxide, and triethylamine should be used, as acid acceptors, to maximize CO2 permeance and CO2/N2 selectivity, respectively. Moreover, the use of hexane solvent and 0 wt% surfactant led to maximum permeance, while, hexane solvent and 0.1 wt% surfactant were needed to reach the highest selectivity. The above level setting of synthesis parameters also resulted in the minimum sensitivity of the fabrication process to the noise factors effects. As shown by the analysis of variance, acid acceptor, and organic solvent types were the most influential parameters on CO2 permeance and CO2/N2 selectivity, respectively. The effects of fabrication method and surfactant concentration, as single factors, on permeation/selectivity responses were also investigated.

Polyethylene glycol-grafted graphene oxide nanosheets in tailoring the structure and reverse osmosis performance of thin film composite membrane

“…This partial hydrolysis of acyl chlorides creates free carboxylic acid groups and impedes complete IP reaction between TMC and MPD monomers thus reducing the cross-linking density of the PA layer. Therefore, the degree of cross-linking of the PA layers can be estimated and compared based on the ATR-FTIR spectra, by calculating the ratio of absorption intensities of amide I (at 1660 cm −1 ) to carboxylic acid C=O stretch (at 1710 cm −1 ) groups: the higher the ratio the larger the cross-linking density 34 . The amide I/carboxylic values for the TFC and TFN membranes are listed in Table 2 .…”

Carbon Dioxide Chemically Responsive Switchable Gas Valves with Protonation‐Induced Liquid Gating Self‐Adaptive Systems

“…We chose the nylon membrane as the porous material to build the PLGS due to its high permselectivity and the possibility of individual optimization [19] . The hydrophilic porous membranes were filled with the AO‐D‐OA functional liquids (Figure S5) [20] .…”

Carbon Dioxide Chemically Responsive Switchable Gas Valves with Protonation‐Induced Liquid Gating Self‐Adaptive Systems

“…We chose the nylon membrane as the porous material to build the PLGS due to its high permselectivity and the possibility of individual optimization. [19] The hydrophilic porous membranes were filled with the AO-D-OA func-tional liquids (Figure S5). [20] In order to directly observe the change of the PLGS before and after CO 2 adsorption, we studied the structure and composition of the membrane by using scanning electron microscopy (SEM) and energy spectrum diagrams in Figure 3a, Figure 3b and Figure S6.…”