Pebax-based membrane filled with photo-responsive Azo@NH2-MIL-53 nanoparticles for efficient SO2/N2 separation

Abstract

The preparation of mixed matrix membranes (MMMs) using metal–organic framework (MOF) as fillers is one of the simple and effective methods to improve the gas permeability and selectivity of membranes, and it has an attractive prospect to achieve controllable gas separation process. Herein, NH2-MIL-53 nanoparticles are synthesized by hydrothermal method and modified by aminoazobenzene (Azo) by decompression loading technology. The multifunctional Azo@NH2-MIL-53 nanoparticles are incorporated into the Pebax matrix to fabricate MMMs for efficient and controllable SO2 separation. Pebax/Azo@NH2-MIL-53–20% membrane exhibits the maximum SO2 permeability of 2570 Barrer with a SO2/N2 selectivity of 717 and the separation process of SO2/N2 has dynamic photo-responsive characteristics under different light conditions, which is attributed to the incorporation of the Azo@NH2-MIL-53. First, the NH2-MIL-53 nanoparticles with high specific surface area of 637 m2.g−1 and pore size of 1.50 nm are introduced into MMMs to construct rich SO2 transport channels, increasing the diffusivity selectivity. Second, the inherent –NH2 groups and introduced -N = N- groups in Azo@NH2-MIL-53 increase the affinity of SO2, enhancing the solubility selectivity. Third, by artificially changing the light conditions to accurately control the conformation of Azo and the pore structure of NH2-MIL-53 is changed, which significantly changes the SO2 adsorption capacity of NH2-MIL-53. Due to light is available in abundance in the form of sunlight, the mixed matrix membrane coupled with photo-responsive MOF can achieve more efficient and energy-saving gas separation process.