Regulation of interlayer channels of graphene oxide nanosheets in ultra-thin Pebax mixed-matrix membranes for CO_(2) capture

For the application of carbon capture by membrane process,it is crucial to develop a highly permeable CO_(2)-selective membrane.In this work,we reported an ultra-thin polyether-block-amide(Pebax)mixedmatrix membranes(MMMs)incorporated by graphene oxide(GO),in which the interlayer channels were regulated to optimize the CO_(2)/N_(2) separation performance.Various membrane preparation conditions were systematically investigated on the influence of the membrane structure and separation performance,including the lateral size of GO nanosheets,GO loading,thermal reduction temperature,and time.The results demonstrated that the precisely regulated interlayer channel of GO nanosheets can rapidly provide CO_(2)-selective transport channels due to the synergetic effects of size sieving and preferential adsorption.The GO/Pebax ultra-thin MMMs exhibited CO_(2)/N_(2) selectivity of 72 and CO_(2) permeance of 400 GPU(1 GPU=106 cm^(3)(STP)·cm^(2)·s^(-1)·cmHg^(-1)),providing a promising candidate for CO_(2) capture.

Screening and design of COF-based mixed-matrix membrane for CH_(4)/N_(2) separation

Membrane separation is a high-efficiency,energy-saving,and environment-friendly separation technology.Covalent organic framework(COF)-based mixed-matrix membranes(MMMs)have broad application prospects in gas separation and are expected to provide new solutions for coal-bed methane purification.Herein,a high-throughput screening method is used to calculate and evaluate COF-based MMMs for CH_(4)/N_(2) separation.General design rules are proposed from thermodynamic and kinetic points of view using the computation-ready,experimental COFs.From our database containing 471,671 generated COFs,5 COF membrane materials were screened with excellent membrane selectivities,which were then used as the filler of MMMs for separation performance evaluation.Among them,BAR-NAP-Benzene_CF_(3) combined with polydimethylsiloxane and styrene-b-butadiene-b-styrene show high CH_(4) permeability of 4.43×10^(-13) mol·m·s^(-1)·Pa^(-1)·m^(-2) and high CH_(4)/N_(2) selectivity of 9.54,respectively.The obtained results may provide reasonable information for the design of COF-based membranes for the efficient separation of CH_(4)/N_(2).

Formulation of Mixed-Matrix Membrane (PSF/Zeolite) for CO<SUB>2</SUB>/N<SUB>2</SUB>Separation: Screening of Polymer Concentration

This research investigates the permeability of CO2 and N2 as well as selectivity of CO2 over N2 of polysulfone (PSF) mixed matrix membranes filled with zeolite 4&Aring particles. The membranes were prepared by solution-casting method and utilized to determine the permeation rates of N2 and CO2. It was characterized by FTIR and the gas separation performance was analysed by Design of Expert (DOE) method. FTIR result revealed the intensity of peak for sulfone S=O vibration at 1322 cm-1;it was related to O=S=O bound of polysulfone in the sample. The single concentration variable has low outcome, however the mixture concentration interaction was effectively to lead better selectivity of CO2 over N2. In terms of interaction between mixture concentrations, interaction between PSF and N-Methyl-2-pyrrolidone (NMP) has considerable effect on the permeability of CO2 with the highest F value of 0.46 membrane. NMP exhibited a high degree of polarity and hydrogen bonding which led to effect of selective skin and permeation rate. The model regression equations were developed as the potential use for screening the permeability of CO2 and N2 based on the deviation effect of polymer concentration.

2D Cd-MOF and its mixed-matrix membranes for luminescence sensing antibiotics in various aqueous systems and visible fingerprint identifying

The abuse of antibiotics has brought great harm to the human living environment and health,so it is extremely significant to develop an efficient and simple method to detect trace antibiotic residues in various wastewaters.Herein,a new two-dimensional(2D)Cd-based metal−organic framework(Cd-MOF,namely LCU-111)and its mixed matrix membranes(MMMs)is sifted as luminescence sensors for efficient monitoring antibiotic nitrofurazone(NFZ)in various aqueous systems and applied as visible fingerprint identifying.The LCU-111 has good selectivity,sensibility,reproducibility and anti-interference for luminescent quenching NFZ with low detection limits(LODs)of 0.4567,0.3649 and 0.8071 ppm in aqueous solution,HEPES biological buffer,and real urban Tuhai River water,respectively.Interestingly,the luminescent test papers and MMMs allow the NFZ sensing easier and more rapid by naked eyes,only with a low LOD of 0.8117 ppm for MMMs sensor.Notably,by combining multiple experiments with density functional theory(DFT)calculations,the photo-induced electron transfer(PET)quenching mechanism is further elucidated.More importantly,potential practical applications of LCU-111 for latent fingerprint visualization provide lifelike evidences for effective identification of individuals,which can be applied in criminal investigation.

Improved dispersion performance and interfacial compatibility of covalent-grafted MOFs in mixed-matrix membranes for gas separation

Mixed-matrix membranes(MMMs)have received much attention due to their processable advantages of polymer and high permeability and/or selectivity of porous metal-organic frameworks(MOFs)fillers.However,the interfacial defects caused by poor interaction between MOFs with polymers and the agglomeration phenomenon caused by uneven dispersion of MOFs are common problems in mixed-matrix membranes.Currently,the priming protocol is one of solutions to the above problems,but it cannot precisely regulate the dispersion of particles and the interfacial compatibility between two phases.Herein,covalent grafting of polyimide 6FDA-Durene onto the surface of UiO-66-NH2 can mitigate the aggregation of fillers inside the polymeric matrices and improve the interfacial interaction between two phases,thus significantly improving the CO_(2)/CH_(4)separation performance on the as-synthesized MMMs.The explored gas transport mechanism indicated that the improved separation was due to the raise of solubility selectivity.Furthermore,the stronger covalent bond between fillers and polyimide than physical interaction of priming protocol also endows the improved anti-plasticization phenomenon for CO_(2)/CH_(4)separation.

Engineering HOF‑Based Mixed‑Matrix Membranes for Efficient CO_(2) Separation

Hydrogen-bonded organic frameworks(HOFs)have emerged as a new class of crystalline porous materials,and their application in membrane technology needs to be explored.Herein,for the first time,we demonstrated the utilization of HOF-based mixed-matrix membrane for CO_(2) separation.HOF-21,a unique metallo-hydrogen-bonded organic framework material,was designed and processed into nanofillers via amine modulator,uniformly dispersing with Pebax polymer.Featured with the mix-bonded framework,HOF-21 possessed moderate pore size of 0.35 nm and displayed excellent stability under humid feed gas.The chemical functions of multiple binding sites and continuous hydrogen-bonded network jointly facilitated the mass transport of CO_(2).The resulting HOF-21 mixed-matrix membrane exhibited a permeability above 750 Barrer,a selectivity of~40 for CO_(2)/CH_(4) and~60 for CO_(2)/N_(2),surpassing the 2008 Robeson upper bound.This work enlarges the family of mixed-matrix membranes and lays the foundation for HOF membrane development.

用于气体分离的含多孔材料的混合基质膜--从金属有机框架到离散分子笼

混合基质膜(MMMs)将多孔材料与聚合物基质相结合,因其互补特性和协同激活已经在气体分离领域引起了相当大的研究兴趣。多孔材料的可塑性和多样性赋予MMMs可延伸的功能和出色的分离性能。为了发挥MMMs的全部潜力,研究人员关注多孔填料与聚合物基质的合理匹配,以实现这些材料之间界面的增强相容性。在本文中,我们重点介绍采用不同策略将金属-有机框架(MOFs)和金属-有机笼(MOCs)与聚合物基质相结合制备MMMs的最新进展。文中进一步讨论未来MMMs发展所面临的机遇和挑战,并旨在通过合理的材料设计和选择推动MMMs的制备。

Enhance gas-separation efficiency of mixed matrix membranes by lamellarly arranged metal-organic polyhedron

Eliminating the nonselective permeation path inside the mixed-matrix membranes(MMMs)is critical for fabrication of gas separation membranes.We demonstrate that by utilizing the phase separation of block copolymers,we are able to introduce metal-organic polyhedrons(MOPs)with precise pore sizes into a polymer matrix and form an ordered layered structure.We also prove that,by arranging MOP cages into a continuous nanosheet-like layer structure,we are able to generate repeated MOP-effective pathways and deplete the MOP-free permeation pathways,thus enhancing the gas-separation efficiency of MMMs.

Pore engineering of ZIF-8 with ionic liquids for membrane-based CO_(2)separation:bearing functional group effect

CO_(2)separation performance of polymer membranes can be significantly enhanced by selecting porous fillers with high CO_(2)affinity.Ionic liquids incorporation has been recognized as an effective strategy for improving the separation ability of pristine porous fillers.However,the influence of the specific functional groups of ILs in IL@MOF composites on separation performance of MMMs still remains unclear.Herein,we designed three microenvironment-tuned IL@ZIF-8 composites in which the three ILs contain different functional groups(-CH3,–SO3H,and–NH2).Molecular simulation results showed that the NH2-IL@ZIF-8 has a commendable CO_(2)adsorption capacity and CO_(2)/CH4 adsorptive selectivity,and the results were well confirmed by the following experimental data.More importantly,the prepared NH2-IL@ZIF-8 based MMMs also exhibit superior CO_(2)separation performance among the three IL@ZIF-8 based MMMs owning to its high CO_(2)affinity.Thus,this work can provide guidance for designing IL@MOF composites for MMMs fabrication towards gas separation,and the research mode combining molecular simulation prediction and experimental verification can afford valuable reference for material development in membrane separation field.