Preparation And Gas Separation Properties Of Photoresponsive MOF/COF Mixed Matrix Membranes

With the development of global industrialization,a large amount of SO₂gas is discharged,environmental pollution is becoming more and more serious,and the search for efficient desulfurization technology has become a research hotspot in the current scientific research field.Membrane separation technology has received extensive attention due to its simple process,low energy consumption,and convenient operation.The porous frame material has become a research hotspot in the field of membrane gas separation due to its excellent gas absorption.This study aimed to separate SO₂.The metal organic framework（MOF）and the covalent organic framework（COF）were blended with the Pebax 1657 polymer matrix to prepare a mixed matrix membrane.The molecular dissolution-diffusion mechanism realizes SO₂/N₂gas separation.The main research contents are as follows:Adjust the interface of the polymer membrane,and introduce the porous framework material（MOF-Uio-66-NH₂,COF-TpPa-1）with SO₂affinity groups as a filler into the Pebax polymer matrix to prepare a mixed matrix membrane.The introduction of porous framework materials with high specific surface area and porosity can provide more channels for the mass transfer of SO₂gas in the membrane;secondly,the SO₂affinity groups carried by MOF and COF can enhance the adsorption of SO₂and strengthen the mixed matrix Membrane dissolution-diffusion mechanism.In this study,the SO₂permeability of the mixed matrix membranes Pebax/CE-Azo-Uio-66-20%and Pebax/TpPa-1-5%were increased to 166%and174%,respectively,compared with the pure Pebax membrane,and the SO₂/N₂selectivity The relatively pure Pebax membranes are increased to 135%and 263%respectively,which overcomes the Trade-off effect and realizes the simultaneous enhancement of permeability selectivity.At the same time,in order to make the membrane separation with light responsiveness,an azo group（Azo）is introduced into the mixed matrix membrane.By grafting reaction,4’-nitrobenzo-18-crown 6-ether（4’-nitrobenzo-18-crown 6-ether,CE）is reacted with Uio-66-NH₂to prepare CE-Azo-Uio-66,as a filler,was introduced into the Pebax polymer matrix,and the SO₂permeability and selectivity of the Pebax/CE-Azo-Uio-66-20%membrane were measured to increase to 191%and 179%respectively compared with the pure Pebax membrane.Compared with Pebax/Uio-66-NH₂membrane,it has both light responsiveness and significantly enhanced permeation selectivity;through the blending method,TpPa-1 and p AAB are blended and introduced into Pebax high In the polymer matrix,the film is provided with light responsiveness.Taking Pebax/CE-Azo-Uio-66-20%and Pebax/p AAB@TpPa-1-5%as the photo-responsive research objects,under UV-Vis light conversion conditions,the membrane’s SO₂permeability and SO₂/N₂selection The properties showed regular and reversible changes,indicating that the mixed matrix film with azo groups possesses light response characteristics.