Structural Regulation Of Pervaporation Membranes And Intensification Of Molecular Transport Process

With the increasing consumption of fossil energy and the serious environmental pollution,the production of clean energy and the development of sustainable energy have received widespread attention.In order to intensify the pervaporative desulfurization and pervaporative bioalcohol dehydration,pervaporation membranes have been fabricated by using polymer materials and two-dimensional materials as the membrane matrix.The topological structures and chemical properties of the membranes have been regulated by rational designing the physical structure and chemical composition of fillers or intercalators.The molecular transfer mechanisms were synergistically optimized and the molecular transport properties were intensified,in hope of achieving high separation performance.The details are summarized as follows:Employing the strategy of synergistic optimization of multiple mass transfer mechanisms,using the amine-functionalized titanium-based metal-organic frameworks(NH₂-MIL)as carriers to immobilize silver ions(Ag⁺@NH₂-MIL),and then incorporated into poly(ether-block-amide)(Pebax)matrix to fabricate hybrid membranes for thiophene/n-octane separation.The incorporated silver ions regulated the chemical microenvironment of the membranes and constructed facilitated transport channels for thiophene.The silver ions regulated the effective pore structure of NH₂-MIL and afforded with screening effects.The free volume properties of the membranes were optimized by the interference of Ag⁺@NH₂-MIL on the packing of Pebax segments,which promoted the molecular transport.Integrated optimization of multiple transfer mechanisms synergistically increased the permeation flux and enrichment factor with optimal values of 22.11 kg/(m² h)and 5.92.Employing heterostructure to optimize the continuity of molecular facilitated transfer channels,heterostructured laminates(UGO)were created through in-situ growth of amine-functionalized zirconium-based metal-organic frameworks(Ui O)on graphene oxide(GO)nanosheets,and then used as carriers to immobilize silver ions(Ag⁺@UGO).The as-prepared Ag⁺@UGO were incorporated into Pebax to fabricate hybrid membranes for thiophene/n-octane separation.The structure-directing property of GO nanosheets was used to construct relatively continuous pore channels of Ui O,and the efficient immobilization of silver ions was beneficial for facilitated transport channels for thiophene.The incorporated Ag⁺@UGO regulated the physicochemical properties of the membranes and optimized the characteristics of facilitated transport channels,which synergistically improved the permeation flux and enrichment factor with optimal values of 23.40 kg/(m² h)and 7.12.Employing the synergistic effects of bimetallic sites,bimetallic Ni Co-MOFs nanosheets were synthesized through ultrasound-assisted method,and then incorporated into Pebax to fabricate hybrid membranes for thiophene/n-octane separation.The bimetallic Ni Co-MOFs nanosheets featuring coordinated unsaturated bimetallic sites can promote thiophene transport through reversible chemical interactions.Compared with MOFs featuring coordinated unsaturated single metal sites,the synergistic effects of the bimetallic sites improved the molecular transport properties and made the hybrid membrane with superior separation performance with a permeation flux of 21.73 kg/(m² h)and a enrichment factor of 6.45.Two-dimensional laminated membranes for butanol dehydration process were fabricated using graphene oxide(GO)nanosheets as building blocks and functionalized carbon quantum dots(SNQD)as intercalators.SNQD regulated the interlayer spacing and endowed the membranes with superior permeability.SNQD featuring sulfonate groups can improve the hydrophilicity of the membranes and promote the rapid diffusion of water molecules in the interlayer channels.The stability of the membranes was strengthened through non-covalent interactions between SNQD and GO nanosheets.SNQD with unique physical structure and chemical property synergistically optimized the confined transfer mechanism and solution-diffusion mechanism,which can significantly increase the separation performance with a permeation flux of 8877.8 g/(m² h)and a separation factor of 3763.