Carbon Membranes Research Articles

Carbon molecular sieve membranes for water separation in CO2 hydrogenation reactions: Effect of the carbonization temperature

Carbon membranes are a potentially attractive candidate for the in-situ removal of water vapor in CO2 hydrogenation reactions. Their hydrophilicity and pore structure can be tuned by properly adjusting the synthesis procedure. Herein, we assess the effect of the carbonization temperature (450–750 °C) on the performance of supported CMSM in terms of vapor/gas separation, in correlation with changes in their surface functionality and porous structure. FTIR spectra showed that the nature of the functional groups changes with the evolution of the carbonization step, leading to a gradual loss in hydrophilicity (i.e., OH stretching disappears at Tcarb ≥ 600 °C). The extent of water adsorption displays an optimum at Tcarb of 500 °C, with the membrane carbonized at 650 °C being the least hydrophilic. We found that the pore size distribution strongly influences the water permeance. At all Tcarb, adsorption-diffusion (AD) is the dominant transport mechanisms. However, as soon as ultra-micropores appear (Tcarb: 600–700 °C) molecular sieving (MS) contributes to an increase in the water permeance, despites a loss in hydrophilicity. At Tcarb ≥ 750 °C, MS pores disappear, causing a drop in the water permeance. Finally, the permeance of different gases (N2, H2, CO, CO2) is mostly affected by the pore size distribution, with MS being the dominant mechanism over the AD, except for CO2. However, the extent and mechanism of gas permeation drastically change as a function of the water content in the feed, indicating that gas/vapor molecules need to compete to access the pores of the membranes.

Self-Supported Carbon Electrodes with a Carbon Membrane and Co3O4 Nanosheets for High-Performance Enzymeless Glucose Detection and Supercapacitors

Self-Supported Carbon Electrodes with a Carbon Membrane and Co₃O₄ Nanosheets for High-Performance Enzymeless Glucose Detection and Supercapacitors

Facile preparation of conductive carbon-based membranes on dielectric substrates.

Graphene has attracted much research attention due to its outstanding chemical and physical properties, such as its excellent electronic conductivity, making it as a useful carbon material for a variety of application fields of photoelectric functional devices. Herein, a new method for synthesizing conductive carbon membranes on dielectric substrates via a low-temperature thermodynamic driven process is developed. Although the obtained films exhibit low crystallinity, their electrical, wetting, and optical properties are acceptable in practice, which opens up a new avenue for the growth of carbon membranes and may facilitate the applications of transparent electrodes as potential plasma-free surface-enhanced Raman scattering (SERS) substrates.

Carbon electrochemical membrane functionalized with flower cluster-like FeOOH catalyst for organic pollutants decontamination

Decorating active catalysts on the reactive electrochemical membrane (REM) is an effective way to further improve its decontamination performance. In this work, a novel carbon electrochemical membrane (FCM-30) was prepared through coating FeOOH nano catalyst on a low-cost coal-based carbon membrane (CM) through facile and green electrochemical deposition. Structural characterizations demonstrated that the FeOOH catalyst was successfully coated on CM, and it grew into a flower cluster-like morphology with abundant active sites when the deposition time was 30 min. The nano FeOOH flower clusters can obviously boost the hydrophilicity and electrochemical performance of FCM-30, which enhance its permeability and bisphenol A (BPA) removal efficiency during the electrochemical treatment. Effects of applied voltages, flow rates, electrolyte concentrations and water matrixes on BPA removal efficiency were investigated systematically. Under the operation condition of 2.0 V applied voltage and 2.0 mL·min−1 flow rate, FCM-30 can achieve the high removal efficiency of 93.24% and 82.71% for BPA and chemical oxygen demand (COD) (71.01% and 54.89% for CM), respectively, with only a low energy consumption (EC) of 0.41 kWh·kgCOD-1, which can be ascribed to the enhancement on OH yield and direct oxidation ability by the FeOOH catalyst. Moreover, this treatment system also exhibits good reusability and can be adopted on different water background as well as different pollutants.

Polymer Formulation Used in Carbon Membrane Synthesis and Performance Evaluation

Carbon membranes are known for their high performance in the separation of gases, particularly for gases with similar kinetic diameter. For this reason, the investigation of carbon membranes continues to increase their performance by tweaking the formulation and heating strategy. One of the formulation aspects is polymer selection, which plays an important role in determining the success of producing carbon membrane with acceptable performance. This is because each polymer has its own characteristics, which then determines the method to be used to synthesize the carbon membrane. Four types of polymers were identified to produce carbon membranes, which are based on non-modified polymer solutions, modified polymer or polymer solutions, non-commercial organic materials and natural polymers such as natural cellulose. This review discusses the overview performances provided by each material.

Incorporation of aluminosilicate into ZIF-activated carbon membrane for H2/CO2 and CH4/CO2 separation

Incorporation of aluminosilicate into ZIF-activated carbon membrane for H2/CO2 and CH4/CO2 separation

Fibrous cellulose nanoarchitectonics on N-doped Carbon-based Metal-Free catalytic nanofilter for highly efficient advanced oxidation process

N-doped carbon materials have been considered as promising efficient and environment-friendly catalysts for sulfate radical-based advanced oxidation processes (SR-AOPs). Herein, we first report a facile strategy to prepare nanoporous N-doped carbon nanofilters (NCNFs) using cellulose nanofibers (CNFs) and metal–organic framework (MOF) as the superior metal-free catalytic for SR-AOPs. In this work, CNFs are employed as nanoporous templates and binders to fix ZIF-8 for fabricating ZIF-8@CNF membrane, and the as-prepared membrane was converted into NCNFs by a simple pyrolysis process. To evaluate the catalytic degradation performance of the NCNFs, methylene blue (MB) was chosen as a model contaminant. It is found that the NCNFs demonstrate a remarkable efficiency for MB removal by peroxymonosulfate (PMS) activation, and 96 % of MB (10 mg/L) was degraded in 15 min. The catalytic reaction and process including removal and washing are very simple and easy because the nanoporous N-doped carbons are fixed on CNF-derived networks. Furthermore, the reaction parameters including reaction temperature, pH, and catalyst/PMS dosage are also investigated. In addition, a series of radical quenching experiments reveal that non-radical mechanism is responsible for the degradation of MB. Importantly, the NCNFs membrane showed a good reusability by the annealing process and it can serve as a catalytic filter in practical organic dye remediation application. This present work shows that MOF derived metal-free carbon membranes have a promising avenue as catalysts for organic dye degradation and water remediation.

Chitosan derived carbon membranes as protective layers on zinc anodes for aqueous zinc batteries

Chitosan derived carbon membranes as protective layers on zinc anodes for aqueous zinc batteries

Fabrication of fabric-like bacterial cellulose/activated carbon membrane for filtering layer applications of face masks by using textile padding method

PurposeBacterial cellulose (BC) is an ideal alternative filtering material. However, current functionalization approaches for BC have not been fully discovered industrially as well as academically applying textile processing. This study aims to create a sustainable fabric-like membrane made of BC/activated carbon (AC) for applications in filtration using textile padding method, to protect people from respiratory pandemics.Design/methodology/approachFabric-like BC is first mechanically dehydrated then AC is loaded via a textile padding step. The finishing efficacy, properties of fabric-like BC/AC and NaOH pretreatment are analyzed and characterized by scanning electron microscope (SEM), field emission scanning electron microscope (FE SEM), X-ray diffraction (XRD), CIELab color space, color strength (K/S), nitrogen adsorption-desorption isotherm including Brunauer–Emmett–Teller (BET) specific surface area and Barrett–Joyner–Halenda (BJH) pore size and volume.FindingsThis research results in a fabric-like BC/AC with pore diameters of 3.407 ± 0.310 nm, specific surface area of 115.28 m2/g and an efficient scalable padding process, which uses 8 times less amount of chemical and nearly 30 times shorter treating duration than conventional methods.Practical implicationsOur globe is now consuming an alarming amount of non-degradable disposable masks resulting in massive trash buildup as a future environmental problem. Besides, current disposable masks requiring a significant upfront technological investment have posed challenges in human protection from respiratory diseases, especially for countries with limited conditions. By combining a sustainable material (BC) with popular padding method of textile industry, the fabric-like BC/AC will offer sustainable and practical values for both humankind and nature.Originality/valueThis research has offered an effective padding process to functionalize BC, and a unique fabric-like BC/AC membrane for filtration applications.

Covalent organic frameworks for CO2 capture: from laboratory curiosity to industry implementation.

CO2 concentration in the atmosphere has increased by about 40% since the 1960s. Among various technologies available for carbon capture, adsorption and membrane processes have been receiving tremendous attention due to their potential to capture CO2 at low costs. The kernel for such processes is the sorbent and membrane materials, and tremendous progress has been made in designing and fabricating novel porous materials for carbon capture. Covalent organic frameworks (COFs), a class of porous crystalline materials, are promising sorbents for CO2 capture due to their high surface area, low density, controllable pore size and structure, and preferable stabilities. However, the absence of synergistic developments between materials and engineering processes hinders achieving the qualitative leap for net-zero emissions. Considering the lack of a timely review on the combination of state-of-the-art COFs and engineering processes, in this Tutorial Review, we emphasize the developments of COFs for meeting the challenges of carbon capture and disclose the strategies of fabricating COFs for realizing industrial implementation. Moreover, this review presents a detailed and basic description of the engineering processes and industrial status of carbon capture. It highlights the importance of machine learning in integrating simulations of molecular and engineering levels. We aim to stimulate both academia and industry communities for joined efforts in bringing COFs to practical carbon capture.

New insights into phase transition behavior and electrochemistry corrosion of three-dimensional biphenylene.

It is estimated that the annual cost of corrosion in most countries accounts for 3-4% of gross domestic product, far exceeding the losses caused by natural disasters, prompting scientists to continuously search for high-performance anti-corrosion materials. Among these high-performance materials, two-dimensional carbon materials represented by graphene have received widespread attention due to their excellent chemical stability and anti-permeability. However, some studies have found that the poor ability of graphene to bind to the interface and the electrical coupling caused by metallicity make it possible to protect copper from corrosion only for a short period of time. To circumvent these issues, through phase behavior research, interface binding property simulation and corrosion mechanism exploration, we propose a more promising anti-corrosive three-dimensional (3D) biphenylene diamond-like carbon membrane (BP-DLC). The kinetic study results show that due to the Gibbs free energy of biphenylene structures below three layers being lower than 0, few-layer biphenylene can spontaneously generate phase transitions of limited size, forming a biphenylene diamond-like membrane and exhibiting superior mechanical properties and a certain degree of flexibility. Mechanical and electronic performance results further show that there is a strong bonding effect between BP-DLC and the metal surface, which further enhances the bistate heterostructure and prolongs the coating life of BP-DLC materials. Compared with pure graphene and Cu substrates, BP-DLC membranes exhibit stronger corrosion resistance by reducing porosity, increasing charge transfer and hindering the diffusion of corrosion ions to the substrate. This study provides a new strategy for constructing corrosion-resistant materials by designing long-term stable and highly corrosion-resistant diamond-like membranes.

A porous carbon membrane with abundant intrinsic carbon defects as an integrated gas-diffusion electrode for CO2 electroreduction

A highly defective porous carbon membrane (HDPCM) is developed via CO2 thermal etching, which exhibits high efficiency for electrocatalytic CO2-to-CO conversion and can be formulated into an integrated gas-diffusion electrode for direct use in a flow cell.

Computational simulation-driven discovery of novel zeolite-like carbon materials as seawater desalination membranes.

Freshwater is a scarce and vulnerable resource that has never encountered such an extensive focus on a nearly worldwide scale as it does today. Recently, it has been found that desalination powered by two-dimensional (2D) carbon materials as separation membranes has significantly reduced the operational costs and complexity but presents heavy requirements for the structural stability and separation properties of the membrane materials. Here, we combined carbon materials with promising adsorption properties and zeolites characterized by a regular pore structure to obtain a zeolite-like structured carbon membrane Zeo-C and investigated the suitability of the Zeo-C membrane for seawater desalination based on the computational-simulation-driven approach. The results of molecular dynamics (MD) simulations and density functional theory (DFT) calculations revealed that the periodic pore distribution conferred favorable structural stability and mechanical strength to the Zeo-C desalination membrane. The rejection rate of Na+ and Cl- is ensured at 100% under a pressure of 40-70 MPa, and that of Na+ could reach 97.85% even though the pressure increases to 80 MPa, exhibiting superior desalination properties. The porous nature of the zeolite-like structure and the low free energy potential barrier are conducive for reliable adsorption and homogeneous diffusion of salt ions, which facilitates the acquisition of desirable water molecule permeability and salt ion selectivity. In particular, the interlinked delocalized π-network imparts inherent metallicity to Zeo-C for self-cleaning in response to electrical stimulation, thereby extending the lifetime of the desalination membrane. These studies have greatly encouraged theoretical innovations and serve as a guiding reference for desalination materials.

Mini Electrode Based on Chitosan-Activated Carbon Membrane for Detection of Paracetamol in Herbal Medicine

A tube type mini electrode has been made to detect paracetamol levels in herbal medicine, the electrode is made of a glass tube with a diameter of 0.7 cm, a length of 3 cm. As the membrane is a mixture of chitosan, activated carbon from rice husk, and cetyl trimethyl ammonium (CTA)-paracetamol. The internal solution is a standard solution of 0.01 M paracetamol in a solution of phosphoric acid pH 2. The average sensitivity of the paracetamol sensor is (22.60 ± 0.01) mV/decade in a linear concentration range of 10-6 – 5x10-3 M, with an average recovery of (90.6 ± 0.5) %. Paracetamol sensor electrodes can be applied to samples of herbal medicine on the market, with an average error of (9.4 ± 0.1) %.

Carbon nanotube-adsorptive dynamic membrane (CNT-ADM) for water purification

Membrane technology plays an important role in water purification, but there are some significant challenges such as membrane fouling and deep purification efficiency. The work proposes a carbon nanotube-adsorptive dynamic membrane (CNT-ADM), including carbon nanotube (CNT) and membrane module, to solve these problems with low operating cost and high removal efficiency. Above all, on the basis of physical adsorption and membrane separation, a CNT-ADM was prepared by applying “forward filtration” of a CNT solution on an ultrafiltration membrane surface. Then, the effects of preparation time, CNT loading amount, transmembrane pressure (TMP) and shear stress on the morphology and permeability were analyzed to evaluate the preparation performance. Pore blocking models were utilized to explain the influence of CNT loading amount on membrane fouling mechanism. The best optimized condition for CNT-ADM preparation was: agitation speed of 50 rpm, TMP of 1 bar, CNT loading amount of 55 g/m2 and preparation time of 10 min. Furthermore, the optimized CNT-ADM was employed to treat the micro-polluted water. The effects of treatment condition on the micropollutant removal rate and flux were investigated with various shear stresses, TMPs, the amounts of micropollutant and CNT. Compared with the new membrane (below 10 %), CNT-ADM displayed a significant improvement for the micropollutant removal (above 95 % for three cycles), due to the synergy of membrane separation (sustaining CNT layer, separating micropollutant and increasing adsorption time) and adsorption removal (forming CNT layer and adsorbing micropollutant). On the other hand, the adsorption behavior also could effectively reduce the direct contact between membrane and micropollutant, then decreasing membrane fouling. Afterwards, the backwash cleaning was also successfully applied to alter the adsorption saturated CNT and generate the new CNT layer. In final, the implications for CNT-ADM application were discussed. Overall, CNT-ADM exhibits the desirable micropollutant removal and strong anti-fouling capacity, and has a great potential application in the sustainable water purification.

Cellulose-based carbon membranes for gas separations - Unraveling structural parameters and surface chemistry for superior separation performance

Carbon molecular sieve membranes were prepared from the carbonization of a cellulose-based polymeric precursor doped with urea. The addition of urea to the cellulose precursor induces an increase in structural disorder and an increase in pore volume inside the structure of prepared membranes. This unique preparation procedure proved to be an extremely effective method for tuning the pore size of carbon membranes to the desired separations. Urea acts as a pore-forming agent that allows the fabrication of carbon membranes with high porosity. The addition of 2.8 wt% of urea doubled the permeability of the prepared carbon membrane to hydrogen. In addition, a permeability to oxygen of 333 barrer was obtained, without impairing the selectivity. The proposed preparation procedure is compatible with industrial production and scaling, hopefully making carbon membranes a viable solution to produce oxygen-enriched air, recovering of hydrogen from hydrocarbon streams and carbon dioxide removal from natural gas/biogas.

Low-temperature Cu/Zn/SBA-16 integrating carbon membrane reactor for hydrogen production and high CO conversion through water-gas shift reaction

The increasing demand for H2 energy has led to a great amount of research being conducted in a membrane reactor (MR), in which a membrane is applied during the water-gas shift (WGS) reaction. In this study, Cu/Zn/SBA-16 WGS catalysts and carbon molecular sieve (CMS) membranes were integrated into CMS MRs. To improve the CO conversion and H2 yield, C MRs were investigated, and different steam/CO (S/C) ratios were used to evaluate the conversion performance. In this study, a tubular CMS membrane was used as the membrane material for a MR. The as-prepared CMS membrane exhibited excellent selectivity of 185.64 for H2 and CO2 mixed gas, and an ideal H2 permeability of 9.7 × 10−9 mol m−2 s−1 Pa−1 when operated under low temperature/pressure conditions (300 °C/3 bar). The Cu/Zn/SBA-16 catalyst synthesized via coprecipitation was used in the WGS reaction. With a relatively low reaction temperature of 300 °C, 2500 h−1 gas hourly space velocity, and S/C equal to 1.5, the CO conversion efficiency of MR could reach up to 99%, and the recovery of H2 was approximately 76%. However, as the S/C increased to 2, the H2 recovery increased to 99%, whereas the CO conversion decreased to 89% because of the water vapor adsorbed on the active site. The hydrophobic Si/C-modified membrane was further synthesized and showed outstanding performance in CO conversion of over 99% with S/C equal to 2.

Preparation and Characterization of Free-Standing Composite Cellulose-Based Carbon Molecular Sieve Membranes

Carbon membranes with excellent strength and mechanical stability were prepared using a cellulose precursor regenerated from an ionic liquid solution with a low loading of boehmite ceramic nanoparticles, ca. 0.1 wt. %. The precursor films show an asymmetrical structure while, after carbonization, the corresponding carbon molecular sieve membranes (c-CMSM) show a dense structure with a uniform thickness of ca. 22 µm. The c-CMSM exhibited excellent separation performance, well above the Robeson Upper Bound. The permeability of the c-CMSM to hydrogen increased from 300 to 530 barrer and the H2/CH4 permselectivity increased to 473, after adding boehmite nanoparticles. Boehmite nanoparticles act as a microporosity-forming agent without compromising the width of the ultramicropores. The prepared c-CMSM is extremely promising for several applications, namely for hydrogen recovery from methane – H2/CH4 (Robeson index:θ=13.5); biogas upgrading – CO2/CH4 (θ=6.5); CO2 removal from combustion flue gas – CO2/N2 (θ=1.7); and hydrogen recovery from ammonia processes – H2/N2 (θ=4.8).

In-situ growth microcircuits on bacterial membranes to enhance ion capture capability for capacitive deionization

The combination of biotechnology and artificial nanotechnology provide new breakthroughs in the design and manufacture of energy materials. In this work, the porous hollow hyphae carbon membrane with different thicknesses were acquired by biological cultivation approach, along with adsorbed Ni2+ as the in-situ growth points. Then, ultrafine hollow carbon tubes generated on the hyphae surface, forming multi-stage composite membrane (CNTs@MC) with tubules covering large tubes. Subsequently, rich amino functional groups were grafted onto MC (hyphae carbon membrane) surface to further improve its hydrophilicity and capacitance. In addition to the hollow structure, the hyphae carbon surface presents many small holes around 50 nm, which not only provides space for Ni2+ adsorption, but also favors the generation of double-layer capacitance. As secondary structure, ultrafine carbon nanotubes as microcircuits capture more charged ions on hyphae surface, thus offering better capacitance performance. The multistage hollow structure enhances the stability of material during ion adsorption. The grafted amino functional groups and intrinsic heteroatomic defects synergically enhance the wettability and pseudocapacitance of material. In general, large effective specific surface area, abundant surface amino functional groups and intrinsic heteroatomic defects guarantee the high capacitance of material, and also exhibits desirable performance in both solid-state supercapacitors and capacitive deionization applications.

Recycle waste washcloth to design Fe3O4/FeS2/C heterojunction membrane as high-area capacity freestanding anode for sodium-ion batteries

Rechargeable sodium-ion batteries (SIBs) with high-area specific capacity and low cost have attracted increasing attention for large-scale energy storage. In this work, Fe3O4/FeS2 heterojunction encapsulated in carbon membrane (FOSM) was rationally designed as freestanding anode for SIBs by taking the waste washcloth as the carbon supporter following calcined at 650 °C (FOSM-650). The porous carbon fiber skeleton inner could support the outer Fe3O4/FeS2 heterojunction to cast excellent flexibility, providing a bridge for fast electron transfer and relieving volume expansion during the charging/discharging process. Meanwhile, the direct contact of outer Fe3O4/FeS2 particles with electrolyte shortened the diffusion path of Na+, and the Fe3O4/FeS2 heterojunction can also foster fast electron diffusion at the interface. Therefore, as a freestanding anode of SIBs, the FOSM-650 electrode exhibited a specific capacity of 1.25 mAh cm−2 at 0.5 A cm−2 in a half-cell system, 0.5 mAh cm−2 was achieved even at a high current density of 2 A cm−2, and still 0.47 mAh cm−2 was retained after 1000 cycles. Especially, in a FOSM-650//NVP@C full-cell system, the specific capacity was stabilized at 0.58 mAh cm−2 after 10 cycles at a current density of 2 A cm−2, 0.21 mAh cm−2 was still achieved after 1000 cycles. This work not only promotes the development of Fe-based freestanding materials with high area-specific capacity, excellent cycling stability and rate capability, and high energy density for SIBs but also provides an effective and high added-value approach for recycling the waste washcloth for forest protection.