Design And Fabrication Of Mxene-based Supported Ionic Liquid Membrane For CO₂ Capture

Membrane separation technology,which is the most promising new kind of green technology in recent years because of its low energy cost,operability and small footprint,and the pursuit of higher gas permeability and selectivity has become the research hotspot.More and more attention has been paid to the two-dimensional laminar membrane due to its characteristic of regular membrane channels and high permeability,thus the research on the improvement of laminar membrane has beening the tendency current study.In this paper,the laminar membrane prepared by two-dimensional MXene sheets was used as the scaffold.The ionic liquid[BMIM][BF₄]was introduced into the interlayer of membrane which takes the advantage of the unique rigidity of MXene sheets.By adjusting and optimizing the microstructure and chemical environment of the lamellar membrane,an ionic liquid supported liquid membrane?SILM?with excellent performance was perpared.The main research contents and conclusions of this paper are as follows:?1?The MXene laminar membrane was prepared by vacuum filtration,and the ionic liquid[BMIM][BF₄]was introduced into the interlayer of membrane by dropping.On this basis,the MXene laminar membrane and SILM were optimized by adjusting the three methods of variable pressure filtration,shake-assisted deposition and heat treatment,which aimed to find the better match between MXene laminar membrane preparation method and ionic liquid[BMIM][BF4].The MXene laminar membrane with variable pressure filtration,shake-assisted and heat treatment exhibit more regular interlayer channel,which is beneficial to the loading of ionic liquids.By comparing the membrane properties before and after adjusting the preparation method,it is found that the membrane with variable pressure filtration,shake-assisted and heat treatment methods all exhibited higher separation performance than the untreated SILM,respectively.Furthermore,the SILM with three methods shows the best separation performance.The CO₂ permeance of MXene laminar membrane is 11500 GPU and the CO₂/N₂ selectivity is 2.61.The CO₂ permeance of SILM is 570 GPU and the selectivity of CO₂/N₂ reaches 28.5.?2?Based on the membrane preparation conditions obtained in the above part,the MXene was modified with Tiron,and the sulfonic acid group SO3-was introduced to adjust the internal environment of MXene laminar membrane,so as to prepare the ionic liquid supporting liquid membrane modified by Tiron.Tiron can bond closely with titanium oxide on MXene sheets,and the modification of Tiron can be very uniform because of the relatively uniform distribution of functional groups on the surface of MXene.There are two functions of the modification of Tiron:on one hand,Tiron can adjust the d-spacing of laminar membrane,which make it easier for ionic liquids to enter;on the other hand,the surface functional group of Tiron may build an ionization channels in the membrane and thus to enhance the carrying capacity for ionic liquid.Compared with the SILM without Tiron,the CO₂ permeance and CO₂/N₂selectivity of the SILM with 30%wt Tiron reachs 520 GPU and 210,respectively.The enhancement of separation performance of membrane may because of the addition of Tiron lead to a limited interlayer space for ionic liquids,which hindered the close packing of ionic liquids,and further increased the molar volume of ionic liquids,thereby increased the CO₂ dissolved.At the same time,the membrane has excellent long-term operation stability at 5bar at least for 7 days.