Membrane Separation Research Articles

Diffusion-Regulated Interfacial Polymerization of Hierarchically Microporous Polyamide Membranes for Permselective Gas Separations.

Interfacial polymerization has emerged as a robust method for fabricating task-specific polyamide (PA) membranes. However, the limited microporosity of highly cross-linked PA membranes constrains their effectiveness in gas separation applications. Herein, we introduce an ionic liquid (IL)-regulated interfacial polymerization process to fabricate polyamide nanofilms incorporating kinked tetrakis (4-aminophenyl) methane monomers. In situ ultraviolet-visible spectroscopy demonstrates that the diffusion of 1,3,5-benzenetricarbonyl trichloride (TMC) toward the interface increases with the IL/H2O ratio, leading to the formation of a more compact membrane with a higher cross-linking degree. The PA-TAM7/3-60 min membrane exhibits a CO2 permeance of 29.8 GPU and a CO2/CH4 selectivity of 109, exceeding the 2008 Robeson upper bond. Additionally, the highly cross-linked structure imparts the membranes with notable plasticization resistance. Mixed-gas tests (CO2/CH4 = 50/50, v/v) reveal that the PA-TAM7/3-60 min membrane experiences only a 2% reduction in CO2 permeance and a 10% decrease in CO2/CH4 selectivity at a CO2 partial pressure of 300 PSIG, compared to its performance at 30 PSIG. The ease of tuning membrane structure and gas separation performance, along with its excellent plasticization resistance, underscores the potential of these PA membranes for task-specific gas separations.

A superhydrophobic PVDF-based membrane containing Metal-organic framework for efficient Oil-water separation

The discharge of oily wastewater has caused heavy burden to the environment, so it is necessary to solve this problem. Membrane separation, as a simple and efficient separation technology, has attracted widespread attentions in the field of oil–water separation. In this work, a superhydrophobic PVDF-based membrane containing MOFs with small size (ZJU-64-CH3-S) was prepared. ZJU-64-CH3-S with different amounts (200 mg, 400 mg and 600 mg) were added into PVDF to obtain ZJU-64-CH3-S/PVDF membranes, which named as M1, M2 and M3. They displayed ideal hydrophobicity according to the large water contact angle (about 130°). And composite membranes showed good oil adsorption and excellent oil–water separation efficiency. In particularly, the oil flux of M2 reached to 333.33 L/(m2·h) and its oil–water separation efficiency was as high as 99 %. The composite membrane was expected to be used in the field of oil–water separation.

Polyethyleneimine Modified Two-Dimensional GO/MXene Composite Membranes with Enhanced Mg2+/Li+ Separation Performance for Salt Lake Brine.

As global demand for renewable energy and electric vehicles increases, the need for lithium has surged significantly. Extracting lithium from salt lake brine has become a cutting-edge technology in lithium resource production. In this study, two-dimensional (2D) GO/MXene composite membranes were fabricated using pressure-assisted filtration with a polyethyleneimine (PEI) coating, resulting in positively charged PEI-GO/MXene membranes. These innovative membranes, taking advantage of the synergistic effects of interlayer channel sieving and the Donnan effect, demonstrated excellent performance in Mg2+/Li+ separation with a mass ratio of 20 (Mg2+ rejection = 85.3%, Li+ rejection = 16.7%, SLi,Mg = 5.7) in simulated saline lake brine. Testing on actual salt lake brine in Tibet, China, confirmed the composite membrane's potential for effective Mg2+/Li+ separation. In the actual brine test with high concentration, Mg2+/Li+ after membrane separation is 2.2, which indicates that the membrane can significantly reduce the concentration of Mg2+ in the brine. Additionally, the PEI-GO/MXene composite membrane demonstrated strong anti-swelling properties and effective divalent ion rejection. This research presents an innovative approach to advance the development of 2D membranes for the selective removal of Mg2+ and Li+ from salt lake brine.

Polyethylenimine-assisted preparation of Zr-MOF/GO membranes for radionuclide separation

In this study, a zirconium-metal organic framework/graphene oxide (UiO-66-NH2/GO) nanofiltration membrane has been prepared with the assistance of branched polyethyleneimine (PEI). This PEI-assisted method facilitates a more uniform dispersion of UiO-66-NH2 within the GO membrane, thereby enhancing the structural stability of the membrane during membrane separation. The as-prepared membrane has exhibited excellent performance in removing radioactive strontium ions, which is a trending research field in nuclear wastewater treatment. A comprehensive investigation into the separation mechanism of the PEI-UiO-66-NH2/GO membrane has revealed a synergistic effect involving size exclusion and electrostatic repulsion. Furthermore, the PEI-UiO-66-NH2/GO membrane has consistently achieved high strontium rejection across a wide range of strontium concentrations, pH levels, and even in the presence of other interfering ions. More significantly, the membrane has demonstrated remarkably enhanced capacity for selectively separating binary mixtures of cesium and strontium, offering practical relevance. Our results have indicated that the PEI-UiO-66-NH2/GO membrane holds considerable promise for the separation of strontium ions.

Sulfonated polybenzimidazole membrane with graphene oxide additive for 2,3-butanediol/water separation: A molecular simulation

Membrane separation for 2,3-butanediol (2,3-BDO) recovery from fermentation broth is highly valued for sustainable and renewable processes, but it requires efficient membrane materials. This work evaluates the sulfonated polybenzimidazole (sPBI) and its graphene oxide (GO) doped composite membrane for separating 2,3-BDO and water via atomistic simulations. Density functional theory calculations are applied to identify various forms of sPBI structures and quantify their binding interactions with 2,3-BDO and water. Classical molecular dynamic simulations are used to evaluate the structural changes, diffusivity, and selectivity of 2,3-BDO and water in different sPBI models, GO surfaces, and GO-doped sPBI composite models. Our results suggest that sPBI slightly increases the crystallinity of the membrane structures, enhances the adsorption strength for both 2,3-BDO and water, and improves the water/2,3-BDO selectivity by 2–3 times. The GO surfaces display a maximum selectivity at a surface coverage of 0.1–0.15 for both hydroxyl and epoxy surface groups. The addition of GO flakes to sPBI creates new interaction sites for 2,3-BDO and water at the interface of sPBI and GO, and the water/2,3-BDO selectivity of GO-doped sPBI models is further increased up to 3 times. This work illustrates how the integrated addition of sPBI and GO flakes offers a promising approach to selective separation of 2,3-BDO and water, providing theoretical guidance for polybenzimidazole-based membranes in the potential application of 2,3-BDO recovery.

Enhancement of oxygen flux through Nb-doped La0.4Sr0.6FeO3-δ ceramic hollow fiber membranes by Fe exsolution

In recent years, numerous studies have focused on the use of mixed ionic-electronic conducting oxides for coupled oxygen separation and catalytic reactions in membrane reactors. A promising strategy for the efficient fabrication of oxygen separation membranes involves modification of the membrane surface via exsolved metal nanoparticles decoration. Here, we present a detailed characterization of the structural and transport properties of a novel membrane material La0.4Sr0.6Fe0.95Nb0.05O3−δ (LSFNb5). The exsolution of Fe nanoparticles was observed after heating of LSFNb5 in a reducing atmosphere (5 % Н2/Ar) and was confirmed by X-ray diffraction analysis, Mössbauer spectroscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The formation of Fe nanoparticles on the surface of LSFNb5 hollow fiber membrane in the reduction process leads to the enhancement of oxygen fluxes and reduces the apparent activation energy. Kinetic parameters for oxygen transport through LSFNb5 hollow fiber membrane estimated using two different models, are in good agreement with the experimental results. Furthermore, LSFNb5 hollow fiber membrane demonstrates stable performance both before and after surface treatment.

Degradable polyvinyl alcohol/chitosan@carnauba wax superhydrophobic composite membrane for water-in-oil emulsion separation and heavy metal adsorption

At present, many oil-water separation membranes are being developed to purify oily wastewater. However, oily wastewater often contains heavy metal, which are often difficult to dispose during separation. Furthermore, most of the oil-water separation membranes cannot be degraded after scrap, producing pollution to environment. Herein, the polyvinyl alcohol/chitosan@carnauba wax (PCGCW) membrane with heavy metal adsorption and biodegradation performance was acquired by electrospinning and spraying process. The acquired PCGCW membrane had excellent mechanical properties after crosslinking glutaraldehyde (GA). Furthermore, the composite membrane had excellent superhydrophobic property (WCA = 154°) with a rolling angle of 2°, due to the introduction of carnauba wax. Exhilaratingly, for emulsions with surfactant, it had a high separation flux with 19,217 L·m−2·h−1·bar−1 and splendid an oil purity over 99.9 %. Besides, the efficiency of oil purity and separation flux remained stable even after 10 separations. In addition, the PCGCW membrane had the ability to adsorb heavy metals with adsorption capacity of 51–106 mg/g for Cu2+, Fe3+, Co2+ ions. Foremost, the superhydrophobic PCGCW membrane was biodegradable, with degrading 29.76 % within 40 days. The prepared composite membrane had the advantages of low cost, high separation flux, great repeatability, adsorbable heavy metals and degradability, which had a vast application prospect.

Cation-modulated permselectivity regulation of polyelectrolyte nanofiltration membranes for water purification

Polyelectrolyte multilayer (PEM) membranes fabricated by layer-by-layer (LBL) assembly have been widely adopted for nanofiltration (NF) due to their unique merits of highly tunable surface charge and pore size. However, current PEM membranes generally suffer from cumbersome preparation procedures and unsatisfying water permeance and/or solute retention rates, which stymie their practical applications. This study discloses a facile and effective method to deliberately regulate the interactions between polyelectrolytes and their LBL assembly behaviors by using cations with various valences and sizes as the modulators. Compared with the acquiescent background electrolyte NaCl, the PEMs modulated by divalent cations (i.e., Ca2+) exhibit intensified surface electronegativity with dense packing structures, and the resulting PEM membranes thus show high rejections for both inorganic salts (i.e., 94.0 % for Na2SO4) and negatively charged emerging micropollutants (EMPs) (i.e., 94.9 % and 99.9 % for tetracycline hydrochloride and perfluorododecanoic acid, respectively). In contrast, monovalent cations (i.e., Li+) lead to the formation of PEMs with loose structures and strong surface electronegativity, which endow the PEM membranes with a high water permeance of 15.0 LMH/bar and slightly reduced solute rejections. Nevertheless, the retention rates of Na2SO4 and perfluorooctanoic acid still surpass those obtained by the NaCl-modulated PEM membrane. Interestingly, trivalent cations such as Fe3+ and Al3+ are unable to facilitate the formation of an intact PEM. Characterization data and theoretical models imply that cations play a pivotal role in the stacking structure of PEMs through synergistically modulating polyelectrolyte-counterion interactions and the overcompensation and subsequent site diffusion of polyanions. This work demonstrates an effective approach to finely tune the nanostructure and permselectivity of the PEMs, which provides a valuable platform for the rational design of PEM NF membranes for effective separations of salts and EMPs.

Electron beam induced graft polymerized anti oil-fouling biaxial polypropylene membrane with harsh environment tolerance

The intrinsic hydrophobic behavior of biaxial-oriented polypropylene microporous membrane limits its broad application area by leading serious membrane fouling. An environment-friendly, practical, and facile to large-scale prepared surface modification process is designed to enhance the membrane wettability and oil-fouling. By employing electron beam radiation, acrylic acid, and polyvinyl alcohol in the pre-irradiation-induced graft polymerization process, a micro-nano structure was developed and the surface roughness was increased from 66.5 nm to 99.3 nm. Enhancing the grafting ratio further reduces the pore size of the final modified membrane from 54 nm to 25 nm, which is significantly smaller than the size of the emulsified oil droplet. By modifying the morphological and structural characteristics of the grafted membrane, excellent oil-fouling resistance features are attained with UWOCA value 161° and separation efficiency of 99.3 %. Moreover, the theoretical explanations for hydrophilicity and oil-fouling resistance of modified membranes are also developed using DFT calculations and the Hermia model, which shows alignment with experimental data. Consequently, considerable improvements in wettability, thermal and mechanical behavior are obtained by this facial surface modification approach, which could further broaden the modified membrane's applications area in membrane separation technology while lengthening its service life.

Healable, Recyclable, and Upcyclable Gel Membranes for Efficient Carbon Dioxide Separation.

Ionic liquids (ILs) are prized for their selective dissolution of carbon dioxide (CO2), leading to their widespread use in ionogel membranes for gas separation. Despite their advantages, creating sustainable ionogel membranes with high IL contents poses challenges due to limited mechanical strength, leakage risks, and poor recyclability. Herein, we leverage copolymerized and supramolecularly bound ILs to develop ionogel membranes with high mechanical strength, zero leakage, and excellent self-healing and recycling capabilities. These membranes exhibit superior ideal selectivity for gas separation compared to other reported ionogel membranes, achieving a CO2/nitrogen selectivity of 61.7 and a CO2/methane selectivity of 24.6, coupled with an acceptable CO2 permeability of 186.4 Barrer. Additionally, these gas separation ionogel membranes can be upcycled into ionic skins for sensing applications, further enhancing their utility. This research outlines a strategic approach to molecularly engineer ionogel membranes, offering a promising pathway for developing sustainable, high-performance materials for advanced gas separation technologies.

Super-hydrophilic membranes fabricated by synergistic integration of covalent organic framework nanoflowers and hydrophilic layers for efficient oil-water separation

Despite numerous advancements, the development of super-hydrophilic membranes for efficient oil-water separation remains a significant challenge due to issues such as membrane fouling and the trade-off between selectivity and permeability. This study addresses these issues by innovatively integrating covalent organic framework nanoflowers with hydrophilic layers of polydopamine and polyethylene glycol. The research introduces a novel membrane, DP/COF3/PVDF, fabricated through a layer-by-layer self-assembly process and subsequent co-deposition of dopamine and PEG, which combines the nanostructured COF with a hydrophilic coating. Experimental results reveal that the optimized membrane exhibits remarkable hydrophilicity, with a water contact angle of 17.0° and an underwater oil contact angle of 176.9°. Notably, the membrane achieves an impressive pure water flux of 3919.9 L m−2 h−1 bar−1 and a rejection rate exceeding 98.0 % across various oil-water emulsions, significantly outperforming traditional membranes. The membrane exhibits superior antifouling capabilities and stability over ten cycles of use, with negligible flux decline and consistent rejection rates, showcasing robust durability and reusability. This study's findings highlight the potential for developing next-generation super-hydrophilic membranes with improved oil-water separation efficiency and durability.

High-Capacity Zinc Anode Enabled by a Recyclable Biomass Bamboo Membrane Separator.

Aqueous zinc ion batteries have gained attention as viable energy storage systems, yet the occurrence of detrimental side reactions and Zn dendrite formation undermines the efficiency of Zn anodes. Controlling water activity have proven to be an effective strategy in mitigating these challenges. However, strategies such as electrolyte design and electrode protection layer show weakness to varying degrees. Here, a new oxygen-functionalized biomass bamboo membrane separator (denoted as BM) is proposed to restrain the activity of water molecules. This BM separator features a unique, multi-tiered 2D interlayer that facilitates rapid ion diffusion. Additionally, the oxygen functional groups of the BM separator can form hydrogen bonds with water molecules, effectively transforming water molecules from a free state to a bound state. Consequently, the Zn/Zn asymmetric coin cell using BM can work at the ultrahigh rate and capacity of 30 mA cm-2 and 30mAhcm-2 for more than 80h while its counterparts using glass fibercan barely work. Moreover, full cells using BM separator exhibited a capacity retention of 89.7% after 1000 cycles at 10Ag-1. This study reveals the important influence of water-limited activity on Zn anode protection and provides an avenue for the design of novel separator.

Design and fabrication of high-performance ultrafiltration membranes for low-temperature conditions

The influence of cold weather conditions on ultrafiltration (UF) membrane performance is noteworthy. Investigating alterations in UF membrane fouling behavior under low-temperature conditions and developing strategies to enhance their performance holds significant importance for advancing membrane separation technology in cold regions. We initiate an exploration into how low-temperature conditions impact the permeation and separation capabilities of unmodified PES UF membranes, concurrently scrutinizing the associated influencing mechanisms. Employing molecular design, we strategically incorporate hydrophilic carboxyl-functionalized groups into the molecular structure of poly (aryl ether sulfone) materials. This method facilitates the development of a series of PAES-modified UF membranes (LTM-x%), exhibiting exceptional performance in low-temperature conditions, grounded in the principles of the hydration layer theory. In a low-temperature condition (5±1 °C), the BSA solution flux and SA solution flux of the LTM-80 membrane surpass the pristine PES membrane flux by 187.38 % and 171.82 %, respectively. Notably, compared to the solution flux at room temperature (22±1 °C), the LTM-80 membrane shows only a slight decrease in the 5±1 °C temperature (flux decline rates of 18.52 % for BSA solution and 15.12 % for SA solution), in contrast to the pronounced decline observed in the pristine PES membrane (49.24 % for BSA and 47.67 % for SA). This investigation unveils an effective and viable strategy for designing and developing high-performance UF membranes suitable for cold regions.

Enhanced Vanadium Redox Flow Battery Performance with New Amphoteric Ion Exchange Membranes.

Vanadium redox flow batteries (VRFBs) depend on the separator membrane for their efficiency and cycle life. Herein, two amphoteric ion exchange membranes are synthesized, based on sulfonic acid group-grafted poly(p-terphenyl piperidinium), for VRFBs. Using ether-free poly(p-terphenyl piperidine) (PTP) as the polymer matrix, and sodium 2-bromoethanesulphonate (ES) and 1,4-butane sultone (BS) as grafting agents, We achieve quaternization of PTP through an environmentally friendly process without alkaline catalysts. PTP-ES and PTP-BS membranes exhibit low area resistance, high H+ permeability, and significantly reduced vanadium ion permeability, leading to exceptional ion selectivity, which is 3.06×106Smincm-3 and 4.34×106Smincm-3, respectively,three orders of magnitude higher than that of Nafion115 (0.27×104Smincm-3). The VRFB with PTP-BS achieves a self-discharge duration of 190h, compared to 86h for Nafion 115. Additionally, under current densities of 40-160mAcm-2, PTP-BS shows coulombic efficiencies of 98.1-99.1% and energy efficiencies of 92.0-82.1%, outperforming Nafion 115. The VRFB with PTP-BS also demonstrates excellent cycle stability and discharge capacity retention over 300 cycles at 100mAcm-2. Therefore, the amphoteric PTP-BS membrane shows remarkable performance, offering significant potential for VRFB applications.

Preparation of Pebax based ternary mixed matrix membranes for enhancing CO2 transport and separation

As a type of material for membrane separation in carbon capture technology, mixed matrix membranes (MMMs) have the advantages of simple processing and excellent gas separation performance and have great research prospects. However, the affinity between organic matrix and inorganic fillers is usually poor, and microphase separation occurs at the interface. At the same time, as the filler content increases, the filler particles will aggregate, leading to non-selective defects in the homogeneous membrane and reducing the gas separation performance of MMMs. Herein, the strategy of adding a third component was adopted. Small molecule polyethylene glycol dimethyl ether (PEGDME) was introduced into the Pebax/NH2-MIL-101 membrane to prepare a ternary mixed matrix membrane Pebax/PEGDME/NH2-MIL-101. Adding small molecules as the third component optimized the membrane structure by utilizing the interaction between the third component, inorganic fillers, and polymer matrix, effectively improving the physical microenvironment of gas separation. At the same time, NH2-MIL-101 was modified to PEI-MIL-101, further improving the performance of the mixed matrix membrane. The CO2 permeability of the Pebax/PEGDME/NH2-MIL-101 ternary mixed matrix membrane reached 313 Barrer, and the CO2/N2 selectivity reached 47.7. The CO2 permeability coefficient of Pebax/PEGDME/PEI-MIL-101 membrane reached 286 Barrer, and the CO2/N2 selectivity coefficient reached 54.2. This work provides new ideas for optimizing the gas separation performance of mixed matrix membranes.

Investigation of biodegradable surfactant as a corrosion inhibitor to the cold rolled steel in the membrane separation device process

The membrane process is an effective way to realize resource reutilization. Most membrane devices are made of cold-roll steel (CRS), which is easy to corrode when operating in acid conditions. Herein, the biodegradable surfactant dodecyl dimethyl betaine (BS-12) was used as the inhibitor to protect the CRS in the trichloroacetic acid (TCA) solution. The long-term stability membrane tests showed that adding BS-12 will not harm the membrane performance. The weight loss experiments proved that adding BS-12 with trace amount (10 mg·L−1) endowed the CRS with good inhibition efficiency (95.3 %). The electrochemical tests indicated that the mixed inhibitor- BS-12 works by inhibiting the anode and cathode simultaneously, and the polarization resistance increased to 21 times. The SEM, AFM, and CLSM tests proved that adding BS-12 enabled the CRS surface to remain stable. The FTIR and XPS tests proved that BS-12 adsorbed on the CRS surface via physical and chemical adsorption. The theoretical calculations proved the horizontal adsorption of BS-12 on the CRS surface and the existence of the electron transfer within the BS-12 and CRS. The BS-12 showed great potential in the CRS inhibition of the membrane separation and purification processing.

Ionic liquid-triggered charge regulation of polydopamine-based surface for antibacterial nanofiltration

The charged surfaces with desirable performance are of high concern in membrane separation but there exist challenges to tailor them over a task-specific range. Herein, we propose an ionic liquid (IL)-triggered charge regulation strategy for polydopamine (PDA)-based surfaces by tuning the number and position of amino groups of ILs. By strategically manipulating the location of amino groups in either the anion, cation, or both, we realize a complete inversion in the surface charge nature of PDA coatings from highly negative to negative and even highly positive (zeta potential: −25 mV to +25 mV). This charge inversion triggered by IL is attributed to both the number of protonable groups and shielding effect provided by counter ions. Such charge flip enhances Donna effect when the PDA/IL coatings serve as the skin layer of nanofiltration membranes, thereby enabling high rejection to both negative and positive target molecules (i.e., chlorogenic acids at various pH). Despite charge regulation, ILs with dual amino groups cross link the PDA aggregates, largely narrowing the pore size distribution of the skin layer. The IL cross-linked PDA skin layer with uniform pores thus shows a nearly 100 % rejection to the target solutes. Meanwhile, the IL synchronously endow the PDA coatings with tunable charge characteristics, imidazolium functional groups and exceptional superoleophobicity, compensating for the originally inferior antibacterial activity of membranes in a wide pH range.

Alkaline-resistant covalent organic framework membranes for selective hydroxide ion separation

Alkali holds a pivotal role in the chemical industry, however, the substantial discharge of alkaline wastewater causes a severe waste of resources and environmental pollution. Conventional polymer membranes have ether bonded backbones and form randomly assembled nanochannels, suffering from a weak alkali resistance and a low hydroxide ion selectivity. Covalent organic frameworks (COFs), known for their robust framework structure, highly ordered channels, and tunable channel chemistry, have been considered as the competent candidate for alkaline-resistant membranes for selective hydroxide ion separation. Herein, we fabricate a β-ketoenamine COF (TpTAPB) membrane with a high alkaline resistance via the interfacial growth strategy. After post-sulfonation, the negatively charged channels of sulfonated TpTAPB membrane allows OH- with smaller size and lower charges to pass through while repulsing WO42- ions, achieving a selectivity of OH-/WO42- up to ∼ 60 and surpassing commercial and most reported polymeric membranes. This work expands the application scope of COF membranes in selective alkali separation.

Design and multi-objective optimization of hybrid process of membrane separation and electrochemical hydrogen pump for hydrogen production from biogas

A new hybrid process for hydrogen (H2) production that including membrane separation, electrochemical hydrogen pump (EHP) and steam methane reforming (SMR) was proposed. Firstly, the combination of two different membranes (PEO-CA) is applied to upgrade the biogas and capture CO2. Secondly, to avoid the toxic effect of CO on the EHP catalyst and, more importantly, to improve the H2 purity, the reforming reaction module is supplemented with water gas shift after the SMR. Finally, EHP is used to achieve high purity hydrogen. Simultaneously, the heat and power integration are considered to improve system efficiency. Sensitivity analysis, maximal information coefficient method and response surface methodology are applied to establish the correlation between objectives and parameters. Then, the second generation multi-objective non-dominated genetic algorithm (NSGA-II) is utilized to achieve minimum levelized cost of hydrogen (LCoH) and carbon emission per unit of hydrogen (ECO2). The optimized LCoH is 2.72 $/kgH2, and the ECO2 is 3.24 kgCO2e. Multi-stage membrane carbon capture process enhances CH4 conversion in SMR. The application of EHP reduces energy consumption and enhances hydrogen yield compared to PSA. The innovative use of membrane is hybridized with EHP to achieve the system intensification. The new hybrid process has a significant advantage in terms of ECO2 (37.45% reduction), although the price is higher compared to conventional biogas-to-hydrogen processes. Thus the new process is a promising low-carbon hydrogen production process from biogas.

Recent advances in MXene nanomaterials: Fundamentals to applications in environment sector

AbstractMXenes are a new type of 2D transition metal carbon/nitride or carbonitride, which are composed of Mn+1AXn phase material (MAX phase) through single‐layer or thin‐layer nanosheets obtained by exfoliation. Owning to unique two‐dimensional layered structure, large specific surface area, excellent electrical conductivity and mechanical stability, the MXenes have quickly become a research hotspot due to their magnetic and other properties, and have been widely used in many fields such as electrochemical sensors, energy storage, catalysis, and adsorption. This article summarizes and introduces preparation methods of two‐dimensional materials MXenes, and focus on reviewing their application research progress in the electrochemical sensors and environmental field in recent years, including detection of biomarkers and environmental pollutants, adsorption of heavy metals, adsorption of radiation metals, adsorption of organic matter, selective adsorption of carbon dioxide, membrane separation, sensors, electrocatalysis, photocatalysis, electromagnetic absorption and shielding, etc. A summary and review were conducted, and finally the existing problems and future development at this stage were analyzed.