Advanced Membranes最新文献

Pd membranes can play an important role in H₂ separation and purification for the development of sustainable and renewable energies. By supporting on porous substrates, Pd layer thickness can be reduced to several micrometers, thus improving the H₂ permeance by several orders of magnitude. However, the supported thin Pd membranes are concomitant with pinhole formation due to either fabrication (e.g., electroless-plating) or thermal treatment, which exist as a remarkable challenge for its widespread applications. This study presents a novel and facile approach for self-repair of Pd membrane defects by immersing the stainless-steel supported Pd membranes in PdCl₂ solution. Three membranes were deliberately selected with a low selectivity of 152–1687 (400 ​°C, 0.1Mpa), for which disproportionation reactions between Pd²⁺ and Fe/Cr/Ni at the defect sites spontaneously occur leading to the formation of Pd particles at the exact point of defects. This self-repair process can be enhanced when applying a high pressure of 30–50 ​bar in the PdCl₂ solution for 30 ​min, by overcoming the capillary resistance and penetrating through the pinholes. Interestingly, densely distributed hillocks were observed on the membrane surface probably due to reduction of PdCl₂ under following H₂ treatment, thus increasing the H₂ permeance with a higher effective surface area. The H₂/N₂ selectivity can be improved by more than one order of magnitude (in the best case from 1687 to 8768) and a long-term stability test of 300 ​h was achieved for the repaired membranes, corroborating the application potential of this approach.

3D printing of ceramic materials has gained tremendous attention in recent years due to its high efficiency and competitive prices in the fabrication of advanced ceramics with complex geometric structures. The application of 3D printing for the precision construction of ceramic membranes has demonstrated great promise in enhancing their separation efficiency and expanding their usage scenarios. This review provides an overview of 3D-printed ceramic membranes from different materials and technologies. It covers the research progress of 3D printing for both dense and porous ceramic membranes. Moreover, the challenges of 3D printing technology faced by ceramic membranes are discussed, and potential development directions are prospected.

The development of polymer materials and polymer membrane fabrication techniques in recent years greatly elevates the importance and feasibility of organic solvent nanofiltration (OSN) technology, while challenges from different perspectives still hinder the wider applications of polymer based OSN membranes. This article reviews the OSN membrane research specifically from the perspective of polymer membrane materials, starting by recapping the recent progress of polymer based integrally skinned asymmetric (ISA) and thin film composite (TFC) OSN membranes. Comparing to commercially available polyimide ISA membranes and polyamide TFC membranes, multiple categories of emerging polymer materials result in membranes with much improved permselectivity for highly efficient molecular separation. In view of adopting OSN membranes for engineering applications, this review also summarizes some key challenges unique to polymer membranes including material swelling, physical aging and membrane compaction, and recent efforts to overcome them. The future research direction and application prospects of polymer OSN membranes are briefly discussed in the latter part of the article, noting that improved membrane formation control and crosslinking strategies, and the development of emerging polymer membrane materials is at high necessity to break through the application constraints of OSN in terms of permselectivity and performance stability.

Chitosan (CS) membranes have been widely applied in water/ethanol separation via membrane-based pervaporation, but a bottleneck in the practical application always exists due to their severe swelling behavior in aqueous solution and consequently low permeation flux due to the large membrane thickness. Here, thin film composite (TFC) hollow fiber (HF) membrane with an in-situ-crosslinked ultrathin CS selective layer is developed via multiple supramolecular interaction-crosslinking strategy for efficient water/ethanol separation via pervaporation. With Fe³⁺-phytic acid (PhA) complex pre-deposited on the substrate, the subsequently introduced CS selective layer is in-situ crosslinked via multiple supramolecular interactions, including coordination, electrostatic, and hydrogen bonding interactions. By varying the cycle number of Fe³⁺/PhA assembly and the species of employed organophosphorus acid, the anti-swelling properties of the resultant TFC CS membrane is enhanced and the separation performance is maximized. The optimal TFC-CS-Fe₂PhA₂ membrane with two cycles of Fe³⁺/PhA assembly has a selective layer thickness of 60 ​nm and a corresponding ultrahigh flux of 2.87 ​kg/m² h, coupled with a permeate water concentration of 99.5 ​wt% and good long-term stability for the dehydration of 85 ​wt% ethanol aqueous solution at 50 ​°C. The supramolecular interaction-crosslinking presented in this work provides an efficient and promising strategy for the construction of TFC CS membrane with excellent anti-swelling property and superior separation performance.

Understanding the effects of solvents on organic solvent nanofiltration currently depends on results obtained from small datasets, which slows down the industrial implementation of this technology. We present an in-depth study to identify and unify the effects of solvent parameters on solute rejection. For this purpose, we measured the rejection of 407 solutes in 11 common and green solvents using a polyimide membrane in a medium-throughput cross-flow nanofiltration system. Based on the large dataset, we experimentally verify that permeance and electronic effects of the solvent structure (Hildebrand parameters, electrotopological descriptors, and LogP) have strong impact on the average solute rejection. We furthermore identify the most important solvent parameters affecting solute rejection. Our dataset was used to build and test a graph neural network to predict the rejection of solutes. The results were rigorously tested against both internal and literature data, and demonstrated good generalization and robustness. Our model showed 0.124 (86.4% R²) and 0.123 (71.4 R²) root mean squared error for the internal and literature test sets, respectively. Explainable artificial intelligence helps understand and visualize the underlying effects of atoms and functional groups altering the rejection.

Desalination as a vital technology for removing salts from saline water, is widely employed in municipal water supply, wastewater treatment, saltwater desalination, and chemical purification. The membrane-based desalination technology now offers a cost-effective alternative to other techniques for generating freshwater. Electro-desalination takes advantage of numerous membrane or electrode materials for desalination under electric-driven force, and performs long-term stability and effectiveness for desalinating saline water with various salinity and compositions. Among all the electro-desalination procedures, electrodialysis (ED) and membrane capacitive deionization (MCDI) are two primary forms. This review gives the state-of-the-art in electro-desalination, particularly, the significant applications for ED and MCDI procedures were explored and compared in terms of energy efficiency and consumption. Future challenges and possibilities for electro-desalination applications were discussed and foretasted.

Polydopamine (PDA) depositions, inspired by mussel foot adhesive proteins, represent a versatile method for preparing separation membranes. However, PDA-based nanofiltration membranes are limited by the long preparation time and moderate flux. This work modulated PDA deposition processes with a spiro-piperazine (SPIP) molecule containing two secondary amine groups and a quaternary ammonium salt. The SPIP could be covalently inserted into PDA coating structures via Michael addition reaction to accelerate the deposition process of PDA and reduce its aggregation. In addition, the rigid and spiro configuration of SPIP molecules provides higher fractional free volume and leads to looser and more uniform structures in the PDA coating. As such, water permeance of PDA/SPIP membranes is 73 ​L ​m⁻² ​h⁻¹ bar⁻¹, 4.6 times improved compared with PDA control membranes, while the dye rejection (>99% for Congo red) is maintained high. These results demonstrate that SPIP is an effective molecule for the structure and performance engineering of mussel-inspired PDA nanofiltration membranes.

Extra-corporeal membrane oxygenation (ECMO) systems can perform the roles of the human heart and lungs to realize extra-corporeal oxygenation of blood. This system mainly depends on the gas-blood exchange membrane, the quality of which impacts the oxygenation performance. Currently, the most widely used gas-blood exchange membrane is made of poly(4-methyl-1-pentene) (PMP) hollow fibers. However, plasma leakage often occurs during clinical applications, which decreases the oxygenation performance and the service life and may endanger the patient's life in serious cases. In this work, Hyflon AD/PMP hollow fiber composite membranes were prepared by coating Hyflon AD on the surfaces of PMP hollow fibers to form ultra-thin, dense layers. Compared the plasma leakage time of the composite membrane with that of the pristine PMP membrane, the Hyflon AD60 layer showed great improvement in anti-leakage performance. The Hyflon AD60/PMP hollow fiber composite membrane possessed lower platelet adhesion and protein adhesion than that of the PMP membrane, indicating better blood compatibility of the Hyflon AD60 membrane. Cytotoxicity experiments were conducted to further confirm the biosafety of Hyflon AD60 as a blood contact medical membrane material. Gas permeance and oxygenation performance of the Hyflon AD60/PMP hollow fiber composite membrane were tested to ensure gas exchange efficiency during the gas separation process. Therefore, the optimized Hyflon AD60/PMP hollow fiber composite membrane has potential for clinical use.