MOF-Mediated Interfacial Polymerization to Fabricate Polyamide Membranes with a Homogeneous Nanoscale Striped Turing Structure for CO2/CH4 Separation.

Abstract

Control of the surface morphology of polyamide membranes fabricated by interfacial polymerization is of great importance in dictating the separation performance. Herein, polyamide membranes with a specific nanoscale striped Turing structure are generated through facile addition of Zr-based metal-organic framework UiO-66-NH2 in the aqueous triethylenetetramine phase. Interestingly, accompanied by the degradation of UiO-66-NH2 in aqueous solution, an intermediate complex is in situ formed through the strong interaction between the Zr metal center and the amine group from triethylenetetramine, which can lower amine diffusion and induce a local interfacial reaction, contributing to the generation of a homogeneous nanoscale striped Turing structure. The resulting membranes are used for CO2/CH4 gas separation. Compared with the parent polyamide membrane displaying a CO2/CH4 selectivity of 43.1 and a CO2 permeance of 31.5 GPU, the membrane with 0.02 wt % of UiO-66-NH2 introduced into the aqueous phase shows a higher CO2/CH4 selectivity of 58.3, along with a CO2 permeance of 27.1 GPU. Additionally, when 0.1 wt % of UiO-66-NH2 is incorporated into the aqueous phase, the membrane exhibits a combination of a higher CO2/CH4 selectivity and an enhanced CO2 permeance in contrast with the parent polyamide membrane.