Advanced Membranes最新文献

Organophilic pervaporation (PV) mixed matrix membranes (MMMs) possess huge potential in organic wastewater treatment with merits of environmentally friendly and high-efficiency. The filler dispersion structure inside MMMs is required to explore in depth to upgrade the PV performance. In this study, an ethoxysilyl functionalized ionic liquid (IL-PTES) modified ZIF-8 nanoparticles (IL-PTES@ZIF-8) were synthesized by one-pot method, and then incorporated into the PDMS matrix to prepare MMMs for PV separation of ethyl acetate (EtOAc) from its diluted aqueous solution. The preferential adsorption performances to EtOAc by IL-PTES, especially for the functions of specific chemical groups in IL-PTES, were researched via molecular dynamicssimulation approach. Furthermore, the IL-PTES covered on ZIF-8 surface could crosslink with PDMS chains, thereby enhancing the interfacial compatibility between ZIF-8 and PDMS. Importantly, the self-aggregated IL-PTES subtly “glued” the nanoparticles together to lead IL-PTES@ZIF-8 a relatively continuous and defect-free distribution state. This condition would lead to a high-efficiency molecular pathway with less polymer phase and much relatively continuous ZIF-8 phase with high selectivity. PV results suggested that the MMMs with 15% IL-PTES@ZIF-8 loading displayed an optimal separation performance with an ultra-high separation factor of 492 (158.7% more than that of pristine PDMS membrane) and normalized EtOAc flux of 4.98 ​kg ​μm ​m⁻²·h⁻¹ (2 times as much as that of pristine PDMS membrane) for separating 1 ​wt% EtOAc aqueous solution at 30 ​°C. These findings offered significant advancement toward developing high-performance MMMs enabled by the synergy of MOFs and ionic liquid.

Ubiquitous membrane fouling is a knotty problem in membrane-based sugar-making process, which limits productivity and sugar quality. Especially during decolorization of sugarcane juice by nanofiltration (NF), fouling mechanism is still obscure and the fouling formation is difficult to control effectively. Herein, based on the analysis of the real fouling layer residue, seven components are served as model solutes and foulants to study their NF separation performance and fouling behavior. We found that the coexistence of polysaccharides and proteins had no synergistic enhancement on membrane fouling, yet attenuated fouling layer because the formation of large complex produced more shear-enhanced back diffusion. Chlorogenic acid (CA), as a phenolic pigment and main pore foulant, aggravates the polysaccharides or proteins fouling owing to its bridging effect between membrane and large foulants, especially polysaccharides with high hydrophilicity. Laccase can catalyze oxidation and self-polymerization of CA, not only reducing its accessibility to block the pores and the bridging effect, but also in-situ forming a hydrophilic coating layer on the membrane surface, which is regarded as an effective pretreatment strategy for fouling control. During the cross-flow filtration of real sugarcane juice, the average permeate flux increases by 67.1% and irreversible fouling decreases by 21.2%, showing great application potential due to its biocompatibility and considerable economic benefits. This work not only elaborately elucidates the fouling mechanism among components in cane juice decolorization by NF, but also proposes an innovative approach to reconstitute fouling layer for improving membrane antifouling performance in practical application.

Polyethersulfone (PES) membranes have been widely used as attractive materials especially in the field of blood purification due to their great oxidative, thermal, and chemical stability, as well as outstanding mechanical properties. However, the intrinsic hydrophobic property seriously limits its application because of the relevant side effects, like biofouling, platelet activation, and coagulation. Given the importance of PES membranes for hemodialysis, various modification methods have been developed to address this challenge; and it is necessary to review the research progress in hemocompatibility enhancement of PES membranes, which is also imperative to provide more insights for the development of future PES-based hemodialyzers and perhaps to open the door to extend their applications for the next generation of blood purification instruments, like the wearable artificial kidney. Herein, we review the concept and principles of hemocompatibility for hemodialysis membranes, different strategies developed to improve the hemocompatibility of PES membranes, and the challenges and future perspectives for improvement in hemocompatibility of PES membranes. Most emphasis has been given to the modification strategies including bulk modification, blending modification, and surface modification and their salient features are highlighted.

Asymmetric composite membranes composed of a porous support layer and compact selective layer have been used in many fields. Nowadays, most studies focus on the material design and structure optimization of the selective layer. However, nano-confined pores in the porous support layer can also be used to construct a composite membrane with unique architecture. The functional polymer and nanoporous particles can be embedded in the pores rather than on the support surface to form a composite membrane, which can solve some significant problems, such as the contradiction between integrity and ultrathin thickness of the selective layer, the interfacial adhesion between selective layer and support layer, and the orientation of the selective layer. The separation performance and the stability of the composite membranes are thus improved. Summarized in this review are the latest studies on the formation of composite membranes using confined space of porous support layer which are defined as a nano-confined composite membrane in this review, with the focus on membrane structure, pore property, and fabrication strategy. The summary and outlook are discussed with a perspective on high-performance composite membranes.

The utilization of hydrogen is regarded as the effective approach to arrive at the global carbon-neutrality target. Hydrogen/methane separation is a necessary unit for the hydrogen production in the petroleum industry. The development of high-performance membranes with high thermal, chemical and mechanical stabilities are an important issue for hydrogen membrane separation. This review provides an overview of current research on the process of membrane preparation and their separation performance toward H₂/CH₄ mixtures for the advanced microporous membranes that own high separation performance and high durability. Typical advanced microporous membranes including zeolite, metal organic framework, carbon-based and polymer-based microporous membranes were summarized for H₂/CH₄ separations. The current challenges and future perspectives towards the industrial application of advanced microporous membranes for H₂/CH₄ separation are outlined.

As an emerging research direction, advanced membranes with responsive two-dimensional (2D) nanochannels are developed to mimic biological functions of cell membranes. Tuning the physical and/or chemical properties of the interfaces of nanochannel walls, the mass transport in the artificial 2D channels can be easily managed, analogous to the proteins in the cell membranes that interact specifically with chemical species and adjust conformation responsively adapting to their environments. Such artificial membranes that could regulate their permeability and/or selectivity correspondingly in response to the environmental signals are of particular importance. This review summarizes the recent developments in the functional membranes with responsive 2D nanochannels including the design strategies, stimuli-responsiveness of the nanochannels and the advanced applications of membranes with responsive 2D nanochannels in water purification, molecular separation, energy harvesting and so on. The functional membranes with responsive 2D nanochannels, which are featured with intrinsic intelligence, show great power for use in global sustainable development.

Thin film composite (TFC) membrane, composed of an ultrathin selective layer and a microporous support layer, has exhibited its great potential for pervaporation applications, because of the high permeability, facile fabrication, and individual optimization of the support and selective layers. In this review paper, we summarize the research progress of TFC membranes in pervaporation applications detailly. Herein, pervaporation fundamentals are briefed, including performance parameters and transport mechanisms involved in liquid-liquid separation and pervaporation desalination. The fabrication methods of support and selective layers, i.e., non-solvent induced phase inversion and electrospunning for the former, as well as interfacial polymerization and layer by layer assembly for the latter are elaborated respectively. Furthermore, the optimization strategies of support and selective layers are also summarized, including material section, filler incorporation, membrane-forming condition, co-solvent assistance, and surface modification. Subsequently, the performance status of TFC membranes is analyzed for various applications, including organic dehydration, organic recovery, and desalination. Finally, the challenges and future perspectives are also presented. We hope that this review can give researchers some guidance for the design and further development of TFC membrane in pervaporation processes.

MOF/polymer interface in mixed-matrix membranes (MMMs) has been considered as a crucial issue for achieving highly efficient gas separation performance. In this research, aluminum fumarate framework (A520) based mixed matrix hydrogel self-supported membranes (A520-MMHMs) were prepared by a facile UV photopolymerization. The hydrophilic A520 incorporated into hydrogel polymer effectively avoided the formation of interfacial defects and improved the compatibility between MOF and hydrogel matrix. As a result, the A520-MMHM possessed enhanced CO₂ permeability (∼432.87 Barrer) and CO₂/CH₄ selectivity (∼51.05) in comparison with pure hydrogel membrane. This performance data is very close to the updated McKeown 2019 upper bound, far exceeding the 2008 Robeson upper bound. Therefore, the design of hydrogel membrane incorporated with water-stable MOF may open up a new way for optimizing self-supported hydrogel membrane performance in gas separation.