Yanhui Wu

Metal‐organic framework (MOF) based mixed‐matrix membranes (MMMs) present significant promise for biofuel recovery. However, they are still plagued by key challenges for practical applications, including poor dispersibility of fillers and insufficient selectivity. Herein, a novel dual‐spatial confinement strategy (D‐SCS) to design ionic liquid (IL)‐loaded graphene oxide (GO)/MOF‐polymer MMMs is proposed. MOFs are first confined onto the surface of GO to promote their ordered dispersion in the polymer matrix. Subsequently, ILs are incorporated into the MOF pores to enhance the intermolecular interactions between MOF and isobutanol. By optimizing the alkyl chain length and content of ILs in the MOF pores, the hydrophobicity and free volume of the filler can be balanced. With the application of D‑SCS strategy, the resulting membrane delivered a high permeation flux of 5049.1 g·m ^{− 2} ·h ^{− 1} and a separation factor of 61.01 at 50°C, which were enhanced by 200.6% and 223.5%, respectively, in comparison with the pristine polyether block amide (PEBA, Pebax 2533) membrane. Moreover, theoretical calculations indicate that isobutanol shows higher adsorption selectivity and faster diffusion in GO/MOF‑808‑BMIM/PEBA membrane than in MOF‑808/PEBA and other MOF‑808‑ILs/PEBA membranes. This work provides a new approach for the construction of high‐performance MMMs for efficient biofuel separation.

The permeability–selectivity trade‐off of membrane is a major challenge limiting the development of pervaporation (PV) technology. Rational design of high‐performance mixed matrix membranes (MMMs) has the potential to break off the trade‐off. Herein, a solvent‐assisted linker exchange‐based strategy is reported to introduce fluoroalkyl into metal–organic framework‐808 (MOF‐808). The pore size of fluorinated MOF‐808 can be adjusted with fluoroalkyl of different chain length (like trifluoromethyl and pentafluoropropyl). Then, the fluorinated MOF‐808/polyether block amide (PEBA) MMMs are prepared for the PV of n‐butanol/water. Compared with pristine PEBA membrane, 20 wt% 3F‐MOF‐808(P)/PEBA MMMs (3F = ‐CF₃ group; P = postmodification method) exhibit 69% increase in permeation flux and 33% increase in separation factor in the PV of 2.5 wt% n‐butanol aqueous solutions at 70 °C. Based on Grand Canonical Monte Carlo and molecular dynamics simulations, fluorinated MOF‐808 shows better butanol affinity (pull effect) and stronger water repulsion ability (push effect). And the “push–pull effect” between fluorinated MOF‐808 with butanol/water is helpful to enhance the PV performance of MMMs. The application of “push–pull effect” provides a new strategy for the rational design of high‐performance MMMs, which is of great significance for the in‐depth research and application of PV technology.

To explore the application of forward osmosis (FO) technology in the organic solvent recovery field, we prepared a new solvent-resistant triple layer thin film composite (TFC) membrane on the PI (polyimide) substrate. The deep eutectic supramolecular polymers (DESPs) interlayer was constructed on the substrate to improve the separation performance and solvent resistance. DESPs interlayer was formed by mixing and heating with cyclodextrin as the hydrogen bond acceptor and L-malic acid as the hydrogen bond donor. The chemical changes, surface property and morphology of the composite membrane with DESPs interlayer were characterized. The separation performance and stability of the triple layer composite membrane in organic solvent FO were studied. For the monascorubrin-ethanol system, the permeation flux of TFC/DESPs5-PI membrane could reach 9.51 LMH while the rejection rate of monascorubrin was 98.4% (1.0 M LiCl/ethanol as draw solution), which was better than the pristine membrane. Therefore, this solvent-resistant triple layer composite FO membrane has good potential for the recovery of organic solvents.

Because of the preferential butanol selectivity of some ionic liquids (ILs), an increasing amount of research has appeared regarding their application in butanol separation. In this research, two ionic liquids, namely, 1-ethyl-3-vinylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([EVIM][Tf₂N], IL1) andN-octyl-pyridinium bis[(trifluoromethyl)sulfonyl]imide ([OMPY][Tf₂N], IL2), were applied to modify a mesoporous molecular sieve MCM-41. The IL-modified MCM-41 samples were characterized by XPS, BET, XRD, SEM and TEM. The ionic liquid-modified MCM-41 was incorporated into the polymer PEBA to prepare mixed matrix membranes to study the influences of the filling of IL-modified MCM-41 and operating conditions on the performance of the mixed matrix membrane for butanol pervaporation. The results indicated that the pervaporation performance of the PEBA membrane was enhanced by the incorporation of IL-modified MCM-41. When the temperature of the feeding liquid was 35°C and the mass fraction of butanol was 2.5 wt%, the 5% MCM-41-IL2-PEBA membrane showed a permeation flux of 421.7 g m⁻²h⁻¹and a separation factor of 25.4. The permeation flux and the separation factor of the membrane increased as the temperature of the feeding liquid increased. The results of the long-period experiment suggested that the 5% MCM-41-IL2-PEBA membrane exhibited high stability within 100 h of operation.

Corner separation contributes greatly to the loss and the passage blockage in a compressor stage. In order to mitigate the corner separation and improve the aerodynamic performance of compressors, a novel passive flow control method, an off-surface micro-blade installed upstream of the separation onset location, was proposed. A numerical investigation has was performed in an annular compressor cascade to assess the control effectiveness of the micro-blade. The results show that the location of the micro-blade affects the control effect significantly. The application of the well-designed micro-blade enhances the diffusion capacity considerably under the inflow incidence from −2° to +10°, accompanied by a slight loss reduction at some particular incidences. Detailed analysis of the predicted flow field was carried out to understand the underlying mechanism. It indicates that a “jet” forms upstream of the separation onset location with the application of the micro-blade. The formation of the jet reduces the thickness of boundary layer on the suction surface and builds a “jet barrier” near the endwall to hinder the accumulation of the low momentum fluid. The influence of the incidence was also investigated. It is concluded that the incidence increase has both positive and negative influences on the control effect of the micro-blade. As a result, the performance of the micro-blade is sensitive to the variation of inlet incidence.