Preparation And Gas Separation Performance Of MXene/Pebax Mixed Matrix Membrane

Recent advances in science,technology,and industrialization have resulted in a substantial increase in carbon emissions,posing a significant risk to humans in the form of global climate change.It is,thus,imperative to explore new technologies to promote sustainable development and support the country’s vision of carbon Dafeng and carbon neutrality.Membrane technology for gas separation is regarded as a promising solution for decarbonization due to its eco-friendly nature and easy operation.Unlike commonly used separation technologies such as refinement and extraction,the process does not involve warming or phase change,making it more energy-efficient.Thus,high-performance gas separation membrane technology can play a crucial role in mitigating global warming trends by capturing carbon dioxide.Hybrid membranes with a polymer as a continuous phase coupled with inorganic nanomaterials are highly promising for gas separation.Combining inorganic nanomaterials’ability to screen for gas size and the polymers’easy processibility could significantly enhance the separation film’s selectivity and permeability and overcome the"trade-off"effect,recognizing such membranes as research hot-spot for carbon collection.In particular,2D MXene nanosheets are gaining recognition as attractive inorganic fillers for mixed matrix membranes due to their high surface area,surface hydrophilicity,good compatibility and low diffusion resistance.However,the stability and compatibility of 2D MXene nanosheets with the polymer matrix interface are significant challenges owing to MXenes’susceptibility to oxidation and non-selective cavities and pore blockage,which could seriously affect the membrane’s separation performance.Therefore,current research is focused on developing highly-stable and selective 2D MXene nanosheets incorporated hybrid membranes.The use of 2D MXene nanosheets as inorganic fillers and Pebax 1657 as a polymer matrix was investigated.Several experimental factors were evaluated,including solvent selection,MXene integration,and the dual filling of 0D Mg O and 2D MXene,to optimize MXene/Pebax,NH₂-MXene/Pebax,and Mg O@NH₂-MXene/Pebax filling ratios.The study provides effective methods to improve the mixed matrix membrane interface’s compatibility and enhance gas separation performance through an analysis of the optimal filling and measurement of film properties such as CO₂/N₂ gas permeability,stability,and selectivity.Furthermore,the study provides an in-depth examination of the mixed matrix membrane’s gas separation mechanism.（1）Two different solvent systems,ethanol/water（7:3）and butanol,were employed to prepare the MXene/Pebax mixed matrix membrane through the solvent evaporation system.The study assessed the effects of different solvent systems,MXene filling ratios,and MXene nanoplatelets on membrane and gas separation.The results indicate that the 0.5 wt%MXene-filled mixed matrix membrane has the greatest gas separation performance,with a CO₂ penetration coefficient of 127.72 Barrer and a CO₂/N₂ selectivity of 55,representing a 58.83%and 12.24%increase compared to pure Pebax membrane,respectively.Butanol solvent improved the interface compatibility of the MXene nanotablet and the Pebax polymer matrix and accelerated gel formation at room temperature,thereby effectively fixing the MXene nanoplatelets.Nonetheless,as the MXene filling ratio increases,many stacked nanoscopic flakes form continuous layer channels,impeding the rapid infiltration of CO₂ into the membrane and diminishing its gas separation performance.（2）NH₂-MXene/Pebax mixed matrix film was prepared by modifying the MXene with Silane coupling agent 3-aminopropyltriethoxysilane（APTES）and adding it to Pebax 1657.The optimal NH₂-MXene filling ratio with amino modifiers was determined to be 1.0 wt%,which enhances the interface compatibility of the mixed matrix membrane leading to an increase in CO₂penetration coefficient to 154.12 Barrer and CO₂/N₂ selectivity to 126.33,reflecting a 20.67%and 129.48%improvement compared to the MXene/Pebax-0.5 MMM.The enhanced gas separation performance of the amination-modified hybrid matrix membrane results from the improvement of molecular sieving and promoted transferability within the membrane.（3）Utilizing the synergistic effect of distinct dimension fillers,the Mg O@NH₂-MXene/Pebax dual-filled dosage-type mixed matrix membrane with Pebax polymer is prepared using 0D Mg O and 2D NH₂-MXene as filling agents.The best gas separation performance was obtained when the Mg O to NH₂-MXene ratio was 1:2 at a total content of 1.0 wt%.The mixed matrix membrane showed a 210.68 Barrer CO₂ penetration coefficient,a 36.71%increase compared to NH₂-MXene/Pebax-1.Compared to the MXene/Pebax membrane,the CO₂/N₂ selectivity increased to 77.83 but was not as excellent as the NH₂-MXene film with aminoization modification.The comprehensive analysis of the membrane structure and separation mechanism indicated that Mg O nanoparticles could significantly promote CO₂ transfer within the membrane and enhance the dispersion of short-range interlayer channels of NH₂-MXene nanosheets,thereby enhancing the permeability of the membrane.