Membrane Separation Research Articles

An adaptive and fast emulsion separation Janus membrane

Inspired by the capillary effect in nature (such as water transport in soils) and droplet-drive performance of Nepenthes, a new driving strategy for emulsion separation membrane based on the synergistic effect of capillary force and progressive wettability-induction force was proposed. It is prepared by a one-step, simple continuous, electrospinning process. By adjusting solutions and spinning parameters, the membrane obtains its capillary structure and progressive oleophilicity in one-step preparation. Attractively, the membrane shows separation efficiency and excellent permeability, with a flux of 384801 L m−2 h−1 bar−1 for the oil-water mixture, and the little water content of less than 18 ppm. And for emulsions, the flux even reaches 50000 L m−2 h−1 bar−1 and the separation efficiency reaches 99.95%. Furthermore, the membrane has excellent mechanical-stability: at 80 kPa transmembrane pressure, it can still effectively prevent water's penetration. Drawing inspiration from nature, the incorporation of capillary force and progressive wettability-induction force into the separation membrane as an additional dual emulsion separation driving force proves to be a highly effective and versatile approach. This method provides a way to solve the general flux-efficiency balance problem of oil-water separation and also provides a new strategy for the preparation of separation membranes for various purposes.

Prenatal Surgery for Open Fetal Spina Bifida in Patients with Obesity: A Review of Current Evidence and Future Directions.

Background: Obesity rates have significantly increased globally, affecting up to 40% of women of childbearing age in the United States. While prenatal repair of open fetal spina bifida has shown improved outcomes, most fetal surgery centers exclude patients with a body mass index (BMI) ≥ 35 kg/m2 based on criteria from the Management of Myelomeningocele Study (MOMS) trial. This exclusion raises concerns about healthcare equity and highlights a significant knowledge gap regarding the safety and efficacy of fetal spina bifida repair in patients with obesity. Objective: To review the current state of knowledge regarding open fetal surgery for fetal spina bifida in patients with obesity, focusing on safety, efficacy, and clinical considerations. Methods: A comprehensive literature search was conducted using the PubMed and EMBASE databases, covering articles from the inception of the databases to April 2024. Studies discussing fetal surgery for neural tube defects and documenting BMI measurements and their impact on surgical outcomes, published in peer-reviewed journals, and available in English were included. Quantitative data were extracted into an Excel sheet, and data synthesis was conducted using the R programming language (version 4.3.3). Results: Three retrospective studies examining outcomes of prenatal open spina bifida repair in a total of 43 patients with a BMI ≥ 35 kg/m2 were identified. These studies did not report significant adverse maternal or fetal outcomes compared to patients with lower BMIs. Our pooled analysis revealed a perinatal mortality rate of 6.1% (95% CI: 1.76-18.92%), with 28.0% (95% CI: 14.0-48.2%) experiencing the premature rupture of membranes and 82.0% (95% CI: 29.2-98.0%) delivering preterm (<37 weeks). Membrane separation was reported in 10.3% of cases (95% CI: 3.3-27.7%), the mean gestational age at birth was 34.3 weeks (95% CI: 32.3-36.3), and the average birth weight was 2651.5 g (95% CI: 2473.7-2829.4). Additionally, 40.1% (95% CI: 23.1-60.0%) required a ventriculoperitoneal shunt. Conclusion: While current evidence suggests that fetal spina bifida repair may be feasible in patients with obesity, significant limitations in the existing body of research were identified. These include small sample sizes, retrospective designs, and a lack of long-term follow-up data. There is an urgent need for large-scale, prospective, multicenter studies to definitively establish the safety and efficacy of fetal spina bifida repair in patients with obesity. Such research is crucial for developing evidence-based guidelines, improving clinical outcomes, and addressing healthcare disparities in this growing patient population with obesity.

Biochar-based adsorption for heavy metal removal in water: a sustainable and cost-effective approach.

The increasing contamination of aquatic bodies by heavy metals poses a significant threat to environment and human health, necessitates innovative, sustainable and cost-effective remediation strategies. Due to their persistence and toxicity, heavy metals like copper (Cu), lead (Pb), mercury (Hg), and cadmium (Cd) pose severe threats, even in trace amounts. Traditional removal methods of these heavy metals, like chemical precipitation, oxidation/reduction, filtration, ion exchange, membrane separation, and adsorption, are costly, inefficient, and have drawbacks. As an efficient and low-cost adsorbent, biochar has the potential for heavy metal remediation from water. Biochar is a versatile carbonaceous material produced through pyrolysis of organic wastes, emerged as a powerful adsorbent for heavy metal removal from contaminated water. The unique property of biochar makes it an effective medium immobilizing and capturing of heavy metals like Pb, Cd, As and Hg. Various factors affect its adsorption potential and capacity. Feedstocks type, composition, activation methods, and production processes including the pyrolysis temperature, temperature rate and residence time significantly impact the efficacy of biochar. Therefore, this review has assessed, compared, and contrasted different forms of biochar along with their production methods, modification techniques and mechanisms for their potential use as an adsorbent for heavy metal removal from the contaminated water. Modified biochar offers an environmentally friendly and cost-effective solution for water purification and remediation of toxic heavy metals from water. This review highlights the biochar potential as a crucial component for future research projects focusing on water treatment technologies, providing avenues for safer and cleaner water resources.

Polyelectrolyte-modified covalent organic framework membranes for multivalent cation removal

Covalent organic framework (COF) has become a promising membrane material in chemical separations. However, the application of COF membranes for ion separation is still challenging, due to the mismatch between the pore size of COFs (1–5 nm) with the diameter of hydrated ions (<1 nm). Herein, a cationic polyelectrolyte surface modification strategy of COF membranes was proposed, by assembling a cationic polyelectrolyte (PEI, PDDA, PAH) layer on the surface of an anionic COF (TpPa-SO3H) membrane via dip coating. The cationic polyelectrolytes on the membrane surface offered abundant positive charges and reduced the surface pore size, leading to the synergistic enhancement of the size sieving and the electrostatic repulsion. Accordingly, effective rejection of multivalent cations was realized with a significantly increased rejection rate of 97.1 % for MgCl2, compared to that of TpPa-SO3H membrane (10.3 %). Furthermore, the polyelectrolyte-modified COF membrane exhibited desirable separation performance for heavy metal ions in water. The rejection rates for heavy metal salts, including CrCl3, CdCl2, CuCl2, PbCl2 and NiCl2, reached 98.5 %, 97.3 %, 97.0 %, 96.2 %, and 96.0 %, respectively, and remained above 95 % during the 7-day long-term operation test.

Covalent Organic Framework Membranes with Regulated Orientation for Monovalent Cation Sieving.

Continuous covalent organic framework (COF) thin membranes have garnered broad concern over the past few years due to their merits of low energy requirements, operational simplicity, ecofriendliness, and high separation efficiency in the application process. This study marks the first instance of fabricating two distinct, self-supporting COF membranes from identical building blocks through solvent modulation. Notably, the precision of the COF membrane's separation capabilities is substantially enhanced by altering the pore alignment from a random to a vertical orientation. Within these confined channels, the membrane with vertically aligned pores and micron-scale stacking thickness demonstrates rapid and selective transportation of Li+ ions over Na+ and K+ ions, achieving Li+/K+ and Li+/Na+ selectivity ratios of 38.7 and 7.2, respectively. This research not only reveals regulated orientation and layer stacking in COF membranes via strategic solvent selection but also offers a potent approach for developing membranes specialized in Li+ ion separation.

Optimization and Modification of Bacterial Cellulose Membrane from Coconut Juice Residues and Its Application in Carbon Dioxide Removal for Biogas Separation

Driven by environmental and economic considerations, this study explores the viability of utilizing coconut juice residues (CJRs), a byproduct from coconut milk production, as a carbon source for bacterial cellulose (BC) synthesis in the form of a versatile bio-membrane. This work investigates the use of optimization modeling as a tool to find the optimal conditions for BC cultivation in consideration of waste minimization and resource sustainability. Optimization efforts focused on three parameters, including pH (4–6), cultivation temperature (20–30 °C), and time (6–10 days) using Design Expert (DE) V.13. The maximum yield of 9.31% (g/g) was achieved when the cultivation took place at the optimal conditions (pH 6, 30 °C, and 8 days). This approach aligns with circular economy principles, contributing to sustainable resource management and environmental impact reduction. The experimental and predicted optimal conditions from DE V.13 were in good agreement, validating the study’s outcomes. The predictive model gave the correlations of the optimal conditions in response to the highest yield and maximum eco-efficiency. The use of prediction modeling resulted in a useful tool for forecasting and obtaining guidelines that can assist other researchers in calculating optimal conditions for a desired yield. Acetylation of the BC resulted in cellulose acetate (CA) membranes. The CA membrane exhibited the potential to separate CO2 from a CH4/CO2 mixed gas with a CO2 selectivity of 1.315 in a membrane separation. The promising gas separation results could be further explored to be utilized in biogas purification applications.

Preparation and Performance of Organically Modified Montmorillonite Composite Separation Membrane

Preparation and Performance of Organically Modified Montmorillonite Composite Separation Membrane

Hydrophilicity modification of polyphenylene sulfide: A comparative study on the introduction of Zr by physical blending and copolymerization

Polyphenylene sulfide (PPS) is widely used in auto components, machinery parts, electrical accessories, and anti-corrosion coatings, but its hydrophobicity restricts its application in biomaterials, medical equipment, battery separators, and oil pollution separation membranes. To improve the hydrophilicity of PPS, zirconium oxynitrate reacted with 3,5-dichlorosalicylic acid (SA) to generate zirconium-carboxylate (ZrSA). ZrSA was then incorporated into the main chain of PPS through copolymerization to yield hydrophilic copolymers (ZrSA-PPS). Meanwhile, SA was copolymerized into the main chain of the PPS to produce SA-PPS. Next, SA-PPS and ZrO2 were physically blended to obtain hydrophilic composites (ZrO2/SA-PPS). The melting point of ZrSA-PPS ranged from 278.19 to 281.16 °C, which was slightly higher than that of ZrO2/SA-PPS (278.39–279.95 °C), but its crystallinity (34.3–41.2 %) was lower than that of ZrO2/SA-PPS (42.2–51.6 %). The maximum decomposition temperatures of ZrSA-PPS and ZrO2/SA-PPS were increased by about 10 °C, indicating that the Zr–O bonds obstruct the thermally induced movements of the molecular chain. The ZrSA-PPS possessed a tensile strength of 40.8–70.5 MPa and a flexural strength of 46.4–103.4 MPa. The tensile and flexural strengths of ZrO2/SA-PPS (14.6–65.1 Mpa and 23.1–100.3 Mpa) were significantly inferior to that of ZrSA-PPS. This revealed that the ZrSA cross-linked structure can prevent crack propagation. The water contact angle of ZrSA-PPS and ZrO2/SA-PPS were ranged from 59.0° to 76.5° and 61.6°–78.5° (Neat-PPS, ∼87.9°), respectively. The agglomeration of ZrO2 resulted in a slightly higher water contact angle for ZrO2/SA-PPS than for ZrSA-PPS. The enhanced hydrophilicity of ZrSA-PPS benefited from the formation of large chain spacing, strong polar groups, and hydrogen bonds. Our study may shed light on the hydrophilic modification of PPS, which should offer a valuable guide and option for PPS in hydrophilic applications.

Interfacial demulsification and antifouling of oil/water separation membrane by dynamically self-releasing hydroxide ions

Advanced membranes are urgently needed in concentration, purification and separation of various industrial emulsions. However, their performance is impeded by issues such as membrane fouling and the inherent trade-off between separation efficiency and permeation flux. In this work, an interfacial demulsification and antifouling membrane was achieved through self-releasing high concentration of hydroxide ions on the membrane surface in a dynamic manner. These hydroxide ions can facilitate the emulsified oil droplets on the membrane surface to demulsify by greatly decreasing their Debye length and suppressing their electric double layer repulsion. In this way, the emulsified oil droplets could aggregate into large ones and rapidly detach from the membrane surface, mitigating the challenges of membrane fouling and trade-off. Thus, the membrane exhibits outstanding antifouling ability, achieving high efficiency (99.79 %) and flux (3046 L m−2 h−1 bar−1) in long-term oil/water emulsion separation. This ionic self-releasing membrane is easy to manage, requires no reagent consumption, and causes no pollution. This work provides a promising solution and valuable insights into membrane separation and emulsion-related systems.

Constructing the positive electrostatic environments by nanosheet in mixed matrix membranes for efficient CO2 separation

Mixed Matrix Membranes (MMMs) have shown advantages in overcoming trade-off effects, but there is still an urgent need to enhance CO2 separation performance in the design of multifunctional fillers. To overcome the trade-off effects in MMMs, a rational design of fillers with selective recognition for CO2 molecules is an effective strategy. A microporous nanosheet Qc-5-Cu was synthesized and incorporated into a Pebax MH 1657 (Pebax) to prepare MMMs for efficiently separating CO2 from CH4. The H atoms of the aromatic rings on the surface of pores in Qc-5-Cu constructed positive electrostatic environments, which significantly improves the CO2/CH4 separation performance of MMMs. On one hand, the constructed positive electrostatic environments in the MMMs attracted the negatively charged O atoms of CO2 molecules through electrostatic attraction, which effectively accelerated CO2 transport. On the other hand, the positive electrostatic environments established a selective barrier for preventing CH4 transport, achieving high CO2/CH4 selectivity in MMMs. Compared to pure Pebax membrane, the Pebax/Qc-5-Cu-0.5 MMM exhibited a remarkable enhancement of 99.52 % in CO2 permeability (934.24 Barrer) and a significant increase of 37.64 % in CO2/CH4 selectivity (25.01). The constructed positive electrostatic environments of nanosheets in MMMs offers a potential prospect for efficient CO2/CH4 separation.

Controllable Design of Polyamide Composite Membrane Separation Layer Structures via Metal-Organic Frameworks: A Review.

Optimizing the structure of the polyamide (PA) layer to improve the separation performance of PA thin-film composite (TFC) membranes has always been a hot topic in the field of membrane preparation. As novel crystalline materials with high porosity, multi-functional groups, and good compatibility with membrane substrate, metal-organic frameworks (MOFs) have been introduced in the past decade for the modification of the PA structure in order to break through the separation trade-off between permeability and selectivity. This review begins by summarizing the recent progress in the control of MOF-based thin-film nanocomposite (TFN) membrane structures. The review also covers different strategies used for preparing TFN membranes. Additionally, it discusses the mechanisms behind how these strategies regulate the structure and properties of PA. Finally, the design of a competent MOF material that is suitable to reach the requirements for the fabrication of TFN membranes is also discussed. The aim of this paper is to provide key insights into the precise control of TFN-PA structures based on MOFs.

The performance of nanofiltration membranes in seawater and desalination brine applications: Saudi Water Authority experience

The process of dual brine concentration employs an NF-RO-MBC configuration as its fundamental setup. Understanding the ion rejection capabilities of NF in seawater is crucial within this framework. Testing of fourteen commercial NF membranes using Jubail seawater revealed variations in ion rejection capabilities. Twelve membranes operated at a consistent feed pressure of 17.7 bar. The results categorized membranes based on their TDS rejection into high (≥ 45 %), medium (25–45 %), and low (< 25 %) rejection membranes. When concentrating the NF-treated SWRO brine, NF membranes can be utilized in the MBC system. Eight commercial NF membranes were evaluated with SWRO brine, where Na and Cl constituted over 96 % of the TDS. The investigation assessed the concentration performance and secured solid quantity in the reject relative to the feed by applying pressures of up to 40 bar for the conventional NF membranes and up to 65 bar for the newly introduced HPNF membranes. Among these membranes, two conventional and two HPNF membranes exhibited promise for concentrating SWRO brine. In addition, the ion rejection performance of five commercial NF membranes on SWRO brine was examined for a potential RO-NF-MBC configuration, suggesting suitable NF membranes for SWRO brine separation. Lastly, the ion rejection performance was studied in a multistage NF system with varying feed compositions at each stage and compared with projected performance. The accumulated NF membrane performance database will be utilized to optimize the overall membrane system configuration for seawater and brine separation and concentration.

BiOCl-PVDF nanofibrous membrane for synergic oil-water separation and degradation of dye

Polymeric membranes have garnered remarkable attention, attributed to the significant breakthrough in the filtration of oily wastewater. However, the major setbacks of pristine polymeric membranes include susceptibility to fouling and chemical instability. Addressing such issues, this work focusses in the modification of polymer membranes using a metal oxyhalide, such as Bismuth oxychloride (BiOCl). This modification not only enhances water purification capabilities but also strengthens the membrane, protecting it from environmental deterioration and extending its lifespan. BiOCl was integrated into an electrospun pristine nanofibrous polymeric membrane using hydrothermal technique. The synthesized membrane matrix displayed superhydrophilicity and underwater superoleophobicity, effectively separating oil-in-water mixtures and emulsions. Moreover, BiOCl was effectively utilized to assess organic pollutant adsorption and degradation through photocatalysis. In addition, the membrane exhibited exceptional recyclability and withstood harsh conditions, contributing to its mechanical stability. The numerous advantages, enhance the effectiveness of BiOCl modified membrane in water pollution remediation.

Efficient tetracycline degradation via flow-through peroxymonosulfate activation by dual heteroatom-doped wood-derived catalytic membrane

The widespread use of antibiotics in the medical industry and in animal husbandry has led to significant environmental pollution. Effective purification of high concentrations of tetracycline (TC) in practical pharmaceutical wastewater remains a substantial challenge. The integration of advanced oxidation with membrane separation technology shows great application potential. In this study, a P and N co-doped balsa wood membrane (PNWM) were fabricated using heteroatomic doped biochar material, aiming to synergize filtration and catalytic oxidation. The catalytic activity of the PNWM/peroxymonosulfate (PMS) system was systematically evaluated. Targeting TC as the pollutant, the PNWM/PMS system achieved a degradation efficiency exceeding 97 % within 30 min and a total organic carbon (TOC) removal efficiency of 63.9 %, surpassing the performance of unmodified wood-based membrane. These excellent results were attributed to the doping of N and P atoms, which increased surface defects and specific area, thereby enhancing the adsorption and degradation of TC by PNWM. The graphite N facilitated electron transfer, while pyridine N served as active sites for PMS activation. Additionally, the low electronegativity of the P formed electronic regions of varying intensities on the PNWM surface, contributing to PMS activation. The membrane process also enhanced mass transfer during the degradation process. Both radical (·OH, SO4·ˉ, O2·ˉ) and non-radical (1O2, electron transfer) pathways cooperated in TC degradation in PNWM/PMS system. Consequently, heteroatom-doped biochar film materials prepared through simple methods provide a promising approach for the effective treatment of refractory organic pollutants in wastewater.

Building high-speed facilitated transport channels in Pebax membranes with montmorillonite for efficient CO2/N2 separation

ABSTRACT Development of high-performance mixed matrix membranes (MMMs) is of great significance for CO2 separation membrane technology, in order to improve the commercial competitiveness and practical applications. Montmorillonite (MMT) was developed as a dopant to fabricate Polyether block amide (Pebax1074)-based MMMs for strengthening the CO2/N2 separation. The morphology, chemical groups, microstructure, and thermal properties of MMMs were characterised by scanning electron microscope, FTIR spectroscopy, X-ray diffraction and thermal analysis, respectively. The effects of MMT contents, permeation pressure and permeation temperature on the gas separation performance of the Pebax/MMT MMMs were investigated. The results show that the uniformly dispersed dopants MMT in the membrane matrix significantly influence the thermal stability and the structural compactness of MMMs. Moreover, the CO2 permeability monotonously increases in spite of the CO2/N2 selectivity first increasing and then decreasing with the MMT content elevating from 0% to 10% in MMMs. The highest CO2/N2 selectivity could reach to 120.3, along with the CO2 permeability of 130.6 Barrer for the MMMs made by MMT content of 6%.

Thermodynamic efficiency of membrane separation of dilute gas: Estimation for CO2 direct air capture application

Gas separation technology is crucial for addressing environmental issues like CO2 capture to mitigate climate change. While membrane separation is often cited for its efficiency, accurate estimations are scarce. We present estimations based on classical thermodynamics for very lean CO2 composition (400 ppm), revealing rich details in simple systems and deriving guiding principles. Our main conclusion emphasizes the critical necessity of a high membrane separation ratio, and we discuss candidates for achieving this goal.

PTFE composite membrane with peroxymonosulfate activation self-cleaning for highly-efficient oil-water emulsion separation and dye degradation

Combining membrane separation with advanced oxidation technology can make the membrane self-cleaning, extending its service life. However, the preparation of composite membranes with excellent catalytic ability, self-cleaning performance, and stability remains a key research direction. In this study, a PTFE composite membrane with peroxymonosulfate activation self-cleaning ability was successfully prepared by in-situ growth of CoOOH and ZIF-67 on the surface of a l-DOPA/PEI modified PTFE membrane. The as-prepared membrane is superhydrophilic and has significant superoleophobic surfaces underwater, the separation efficiency of the as-prepared membrane for multiple oil-water emulsions exceeded 98.4 %. Meanwhile, the effective degradation of several organic dyes under visible light was simulated, with still high degradation efficiency (>99 %) after 10 cycles. Overall, this study puts forward a approach towards self-cleaning membranes based on PTFE material; the resulting composite membrane's high separation efficiency, stability under repeated use conditions as well as its self-cleaning ability position it as an attractive candidate for long-term wastewater purification applications.

Advanced absorption-storage water molecules strategy reinforces antifouling property for stable oil/water emulsions separation

Constructing membranes with extraordinary resistance to oil contamination under high permeation flux is a considerable challenge. Herein, an advanced absorption-storage water molecules strategy is proposed for constructing the robust hydration layers to achieve effective anti-oil fouling and stable oily wastewater purification. Specifically, metal–organic framework (MOF, UiO-66-NH2) nanoparticles with powerful water-absorbing characteristics are preferentially adsorbed to collect water in oil/surfactant/water systems. Combining excellent water retention, the micro-/ nano-networks formed by attapulgite (APT) could store the water molecules captured by MOF. The synergistic effect of the water-absorbing/water-retaining interactions between the MOF and APT created robust hydration layers defense barriers, which enhanced the resistance of membrane to oil contamination. Furthermore, the abundant hydrophilic groups (e.g., –OH, –NH2 and –CONH2) of chitosan (CS) further improved the membrane surface hydrophilic coverage, permeability and hydration ability. As a result, the developed CS/APT@MOF composite membrane exhibited significant anti-oil fouling capability and realized superior purification property towards various oil-in-water emulsions stabilized by surfactants. The CS/APT@MOF composite membrane demonstrated outstanding oil repellency (flux recovery ratio > 99.6 %, total flux decline ratio < 3.8 %) over 10 cycles under large permeability (>660 L m-2h−1 bar−1). Meanwhile, the constructed CS/APT@MOF composite membrane exhibited stable separation cycle capability (10 cycles) and continuous purification performance (60 min) for different oil/water emulsions. Therefore, this advanced strategy based on absorption-storage water molecules to construct robust hydration layers provides a promising insight for the development of superior antifouling and operationally stable oil/water emulsions separation membranes.

Biochar-Bio-Cu composite superhydrophobic membrane for efficient oil-water separation

This manuscript presents the development of a superhydrophobic textile fabric (SF) for effective oil–water (O/W) separation. A biochar was synthesized by pyrolysis of banana leaves. The bio-Cu nanoparticles (bio-Cu NPs) were synthesized from grape seed extract. The biochar and bio-Cu NPs were used to enhance the surface roughness of the textile fabric. The low-cost, eco-friendly stearic acid was used as a low surface energy material. The SF achieves a water sliding angle of 1 degree and apparent contact angle of 159 degrees, indicating its superhydrophobic nature. The absorption capacity toward silicone oil (SO), toluene, and crude oil (CO) is measured at 102.2 g/g, 98.5 g/g, and 91.0 g/g, respectively, with minimal decrease after ten usage cycles. The SF exhibits outstanding O/W separation efficiencies for CO (99.6%), toluene (98.9%), and SO (97.5%) over ten cycles. Mechanical stability assessments reveal superhydrophobicity retention till a length of abrasion equal to 650 mm. Chemical stability investigations demonstrate SF’s resilience across a pH range of 1–13 over 2 h of immersion. Furthermore, the SF shows a good flux rate toward the oils used. These findings establish a promising advancement in environmental remediation and O/W separation.

Tri-functional carbon membrane for one-step uptake of low-concentration hydrogen to high purity

The uptake of hydrogen (H2) from natural gas pipelines (CH4) through membrane separation technology is an efficient avenue of obtaining H2 resources. Carbon membranes have the potential to be an attractive option for energy-efficient gas separations in the next generation of membranes due to their precise molecular discrimination ability and easy scalability. Here, we report a carbon membrane composed of a mesoporous substrate, seed layer and sieving layer, achieving a one-step uptake with 55.3 × 10-9 mol·m−2·s−1 Pa−1 permeance and a separation factor for H2/CH4 of 359.1 by feeding hydrogen (20 vol%). As revealed by the kinetic diffusion experiment, H2 is transported in mesoporous substrate via Knudsen flow, differing from the transition flow taken by CH4, thus H2 diffusion rates exceed CH4 by an order of magnitude, which substantially increased H2 purity from 20 vol% to higher purity as gas mixtures passed through the substrate. Then, the H2 passed through the seed layer and sieving layer, resulting in a final H2 purity of ∼ 99 vol%, a sharp increase from the initial low concentration. This carbon membrane integrates three functions of capture, pre-separation and purification into one material and provides a new solution for the uptake of H2 from CH4.