Tubular Carbon Membrane Research Articles

Multi-physics modelling and simulation approach with experimental validation for electrocatalytic filtration process: Part A. Optimization of electrodeposition of metal oxides on carbon membranes

• The model helped in a fast and accurate determination of optimum parameters for uniform electrodeposition results. • The model allowed the control and manipulation of deposition parameters. • RMSE values described good agreement between the model and the experimental studies. • The model gave a generalization of the application to various metal oxides. The integration of metal oxidized catalysts on conductive membrane substrates for electrochemical filtration process is an ingenious way to improve their water treatment performance. However, the determination of the optimum parameters for a uniform distribution of the metal particles over the membrane surface conventionally necessitates multiple experiments and is even more difficult to attain uniformity when coating onto non-flat surface geometries. In this work part A of the study, based on finite element method (FEM) in combination with error control and adaptive meshing using the UMFPACK solver of COMSOL Multi-physics software, we developed a model which through simulations helped in a fast and accurate determination of optimum parameters for uniform electrodeposition results of various metals onto tubular geometry coal-based carbon membrane. Experimental studies were also conducted in order to demonstrate the accuracy of the model and the Pearson's correlation coefficient and the root-mean-square error (RMSE) obtained in this work gave values of [0.88, 0.99] and [0.01, 0.1] respectively, confirming the agreement of the model data with experimental data. The difference in optimum parameters observed for each system studied is another evidence that the model allows the control and manipulation of parameters regardless of the depositing species which marks a significant step forward accurate prediction of electrodeposition of catalysts on carbon membranes for electrocatalytic wastewater treatment.

Electrochemical reduction of nitrate in a catalytic carbon membrane nano-reactor

Nitrate pollution is a critical environmental issue in need of urgent addressing. Electrochemical reduction is an attractive strategy for treating nitrate due to the environmental friendliness. However, it is still a challenge to achieve the simultaneous high activity and selectivity. Here we report the design of a porous tubular carbon membrane as the electrode deposited with catalysts, which provides a large triple-phase boundary area for nitrate removal reactions. The achieved nitrate removal rate is one order of magnitude higher than other literatures with high nitrate conversion and high selectivity of nitrogen. The carbon membrane itself had a limited catalytic property thus Cu-Pd bimetal catalysts were deposited inside the nano-pores to enhance the activity and selectivity. When Na2SO4 electrolyte was applied, the achieved single-pass removal of nitrate was increased from 55.15% (for blank membrane) to 97.12% by adding catalysts inside the membrane. In case of NaOH as the electrolyte, the single-pass nitrate removal efficiency, selectivity to nitrogen formation and nitrate removal rate was 90.66%, 96.40% and 1.47 × 10−3 mmol min−1 cm−2, respectively. Density functional theory studies demonstrate that the loading of bimetal catalysts compared with single metal catalysts enhances the adsorption of *NO3 on membrane surface favorable for N2 formation than NH3 on Cu-Pd surface. The application of catalytic carbon membrane nano-reactors can open new windows for nitrate removal due to the high reactor efficiency.

Carbon-based electroactive ion exchange materials: Ultrahigh removal efficiency and ion selectivity for rapid removal of Cs+ ions

Radioactive cesium (137Cs) ions exhibit high-energy gamma radiation and long half-life. When they enter water body, serious environmental problems and damage to the human body are always generated. Herein, an electroactive composite membrane was facilely prepared by uniformly deposition of nickel hexacyanoferrate (NiHCF) nanoparticles on the surface and inner wall of coal-based tubular carbon membrane (CTCM) for rapid and selective separation of Cs+ from wastewater. This NiHCF incorporated CTCM tube exhibited an extremely high removal rate (over 99.99%) over a long period. Meanwhile, it also demonstrated extreme Cs+ selectivities even in the solutions with high coexisting ion concentrations (e.g., Cs+:Na+ = 1:99, Cs+:K+ = 1:99). The rapid and selective Cs+ uptake/release should be attributed to the better dispersion of NiHCF nanoparticles with high selectivity to Cs+ in the CTCM tube, which reduced the mass transfer distance, increased fluid turbulence and accelerated mass transfer rate. It is expected that such a NiHCF incorporated CTCM tube could be a promising alternative of conventional materials for the separating of radioactive Cs+ ions.

Incorporation of thermally labile additives in polyimide carbon membrane for hydrogen separation

In this study, three thermally labile additives microcrystalline cellulose (MCC), nanocrystalline cellulose (NCC), and polyvinylpyrrolidone (PVP) were introduced to the P84-copolyimide (PI) solution. PI-based carbon tubular membranes were fabricated using dip-coating method, followed by sample characterizations in order to determine their structural morphologies, thermal stability and gas permeation performance. NCC was added as the membrane pore former for the hydrogen gas (H2) separation. While tests involving pure H2 and N2 permeation were carried out at room temperature, carbon membranes were carbonized at a final temperature of 800 °C, with the heating rate of 3 °C/min under the Ar flow. Excellent result of H2/N2 selectivity was obtained with value of 430.06 ± 4.16. Addition of NCC has significantly increased the number of pore channels in the membrane, hence, contributing to high gas permeance and selectivity. NCC has shown potential as a good additive for an enhanced hydrogen separation performance.

WITHDRAWN: Preparation and characterization of polyimide carbon membrane concerning thermally labile additives for hydrogen separation performance

Abstract In this study, thermally labile additives, microcrystalline cellulose (MCC), nanocrystalline cellulose (NCC), and polyvinylpyrrolidone (PVP) were introduced to the P84-copolyimide (PI) solution. The dip-coating method was used to fabricate PI-based carbon tubular membranes, followed by several characterizations in order to determine their structural morphology, thermal stability and gas permeation performance. NCC was added as the membrane pore former for the hydrogen gas (H2) separation. The addition of NCC had significantly increased the pore channels in the membrane, hence, contributing to high gas permeance and selectivity. Tests involving pure H2 and N2 permeation were carried out at room temperature. Carbon membranes that were carbonized at a final temperature of 800 C, with the heating rate of 3 °C/min under the Ar flow had achieved excellent H2/N2 selectivity of 434.68 ± 1.39, hence, proving the potential of NCC as a good additive.

Gas Separation Performance through Carbon Membrane: The Effect of Polymer Composition

A comprehensive requirement in terms of efficient strategies in collecting reasonably high purity of H2 is predicted due to the development of hydrogen (H2)-based economy. The purpose of a H2- selective membrane is to exploit the high diffusivity features of H2 and also to limit the consequence of lower solubility. Owing by its highly permeable and selective characteristics, carbon membranes provide great potential in gas separation industry. Hence, the objective of this study is to examine the effect of carbonization parameter, in particular the composition of polymer on the properties of gas separation. Matrimid 5218 was used as a precursor for the fabrication of carbon tubular membrane to manufacture a carbon membrane with high quality through the process of carbonization. The surface of tubular ceramic tubes was coated with polymer solution via dip-coating technique. The dip-coating method provides an excellent potential in the manufacture of defect-free carbon membrane. The resultant Matrimid 5218-based carbon tubular membranes were characterized in terms of structural morphology using scanning electron microscopy (SEM), chemical structure using Fourier transform infrared (FTIR), thermal stability, and gas permeation properties using pure gas permeation system. The best formulation for Matrimid 5218-based carbon tubular membrane fabrication was shown by the polymer solution containing 15wt% of Matrimid 5218. The highest H2/N2 selectivity of 401.08±2.56 was achieved by carbon membrane carbonized at 800°C with 2°C/min of heating rate.

Uniformity control and ultra‐micropore development of tubular carbon membrane for light gas separation

AbstractTubular carbon molecular sieve (CMS) membranes have been recognized as a potential module for commercial application due to its high mechanical strength and large surface area. However, the carbon layer uniformity was restricted by substrate texture and dope fluidity when the dip‐coating method was used. This study evaluated the influence of various parameters of dip‐coating with an integrated vacuum‐assisted system, including solvent vaporization rates, vertical immersion/withdrawal velocity, vacuum degree, dope composition, coating cycles on the microstructure, and gas separation performance of CMS membranes. Using vacuum assistance and a low‐vaporization solvent minimized the influence of viscosity and gravity on dope fluidity as a result of fast phase inversion. The as‐prepared tubular CMS membranes showed enhanced perm‐selectivity according to a H2/N2 gas selectivity of 8.8, a CO2/N2 gas selectivity of 6.7, a H2 permeability of 464 barrer, and a CO2 permeability of 356 barrer.

Polyimide Based-Carbon Membrane: Effect of Pyrolysis Environment

Tubular carbon membrane was prepared from BTDA-TDI/MDI (P-84) polyimide as a main precursor that blends with nanocrystalline cellulose (NCC) through controlled pyrolysis condition. The effects of the final pyrolysis environment on

Influence of dip-coating times towards oxygen separation performance

Several advantages possessed by carbon membrane such as can be easily processed, high gas separation performance and requires adequate amount of energy compared to the conventional separation process are the reasons it is deemed as the future media of separation. This study utilized PI blends and nanocrystalline cellulose (NCC) to prepare the tubular carbon membrane in order to investigate its fabrication. The effect of dip-coating duration (15, 30, 45, and 60 min) on physicochemical properties O2/N2 separation was determined. Carbonization was done at 800 °C with 3 °C/min rate of heating under argon gas flow (200 mL/min). Tests of pure gas permeation were conducted in order to study the transport mechanism of prepared carbon membrane at ambient temperature and 8 bar of feed pressure. Carbon membrane with O2 permeance of 29.92 ± 1.44 GPU and O2/N2 selectivity of 9.29 ± 2.54 were obtained after 45 min of dip coating.

Tubular carbon membrane for Hydrogen separation: Effect of Pyrolisis condition

Hydrogen (H2)-based economy development is expected to create extensive need for efficient collecting strategies of fairly high purity H2. The aim of a H2-selective membrane is to manipulate H2’s high diffusivity characteristics as well as to restrict the outcome of lower solubility. Carbon membranes offer high potential in gas separation industry due to its highly permeable and selective. Therefore, this study aims to investigate the effect of pyrolisis temperature on the gas separation properties. Matrimid 5218 used as a precursor for carbon tubular membrane preparation to produce high quality of carbon membrane via pyrolisis process. The polymer solution was coated on the surface of tubular ceramic tubes by using dip-coating method. Dip-coating technique offer high potential in fabricating defect free carbon membrane. The polymer tubular membrane was then carbonized under argon atmosphere at 600, 700, and 800, and 900oC with heating rate of 2 oC/min. Matrimid 5218-based carbon tubular membranes were fabricated and characterized in terms of its structural morphology, chemical structure, thermal stability, and gas permeation properties by using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and pure gas permeation system, respectively. The highest H2/N2 selectivity of 401.08±2.56 was obtained for carbon membrane carbonized at 800oC with heating rate of 2oC/min

Effect of Polymer Concentration on Matrimid 5218 based-Carbon Membrane for H2 Separation

Hydrogen (H2)-based economy development is expected to create extensive need for efficient collecting strategies of fairly high purity H2. The aim of a H2-selective membrane is to manipulate H2’s high diffusivity characteristics as well as to restrict the outcome of lower solubility. Carbon membranes offer high potential in gas separation industry due to its highly permeable and selective. Therefore, this study aims to investigate the effect of carbonization parameter, i.e., polymer concentration on the gas separation properties. Matrimid 5218 was used as a precursor for carbon tubular membrane preparation to produce high quality of carbon membrane via carbonization process. The polymer solution was coated on the surface of tubular ceramic tubes using dip-coating method. Matrimid 5218-based carbon tubular membranes were fabricated and characterized in terms of its structural morphology, chemical structure, thermal stability, and gas permeation properties by using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and pure gas permeation system, respectively. The polymer solution containing 15 wt% Matrimid 5218 shows the best formulation for the preparation of Matrimid 5218-based carbon tubular membrane. The highest H2/N2 selectivity of 401.08±2.56 was obtained for carbon membrane carbonized at 800oC with heating rate of 2oC/min.

Effect of Thermal Soak Time Towards Polyimide Based-Carbon Tubular Membrane

Tubular carbon membrane (TCM) was prepared form BTDA-TDI/MDI (P-84) polyimide (PI) has a main precursor that combines with nanocrystalline cellulose (NCC) through controlled carbonization condition. Consideration of the thermal soaking time through the heating process is needed to maintain the proficiency of resultant TCM’s. Thermal soaking time of 30 minutes, 60 minutes, 90 minutes, and 120 minutes was investigated to study the gas properties of the final TCM’s. In the course of TCM’s separation, single gas permeation experiments of CO2 and N2 are performed to investigate the transport mechanism. The PI / NCC TCM’s developed at 120 min of thermal soak time from this study showed the most impressive CO2/N2 performance, selectivity of 66.32±2.18 respectively.

PI/NCC Carbon Membrane: Effect of Heating Rates Towards Oxygen Separation Performance

Separation of oxygen and nitrogen gas was considered by utilizing tubular carbon membrane (TCMs) arranged from polymeric precursors. A coating methodology called dip coating strategy was utilized to manufacture the TCMs utilizing P84 co-polyimide and Nanocrystalline cellulose (NCC) as the primary precursor and added additives individually. Past examination has demonstrated that properties of PI/NCC can be adjusted by changing the carbonization parameter i.e. time, temperature and condition. The statement of PI/NCC on the tubular supported help was utilized to deliver an assortment of TCMs for gas separation by basic carbonization process. In this examination, the heating rates was controlled to watch the impact of TCMs on gas permeation by setting the heat rates at 1, 3, 5, and 7 °C/min. It was demonstrating that the gas separation performance was profoundly influenced by the carbonization heating rates amid the manufacture of PI/NCC-based carbon membrane. Likewise, heat rates at (3 °C/min) demonstrates an enhancement in the membrane selectivity and separation performance.

Oxygen separation through p84 copolyimide/nanocrystalline cellulose carbon membrane: Impact of heating rates

Separation of oxygen and nitrogen gas was studied by using tubular carbon membranes (TCMs) prepared from polymeric precursors. A coating procedure called dip-coating technique was employed to fabricate the TCMs using P84 copolyimide (PI) and nanocrystalline cellulose (NCC) as the main precursor and additive, respectively. Previous study has proved that properties of PI/NCC can be altered by changing the carbonization parameter, i.e. time, temperature, and environment. PI/NCC deposition on the ceramic tubular support was employed to produce diverse TCMs for gas separation via simple carbonization process. In this study, manipulation of heating rate was done to observe the effect of TCMs on gas permeation by setting the heating rate at 1, 3, 5, and 7 °C min–1. It was proved that heating rate during PI/NCC-based carbon membrane fabrication played a significant role in gas ideal selectivity test. In addition, heating rate at (3 °C min–1) showed an improvement in the membrane ideal selectivity but a reduction in the permeability.

RETRACTED: The influence of coating-carbonization cycles toward P84 co-polyimide/nanocrystalline cellulose

This article has been retracted. Please see https://doi.org/10.5802/crchim.43

The performance of CO2/N2 separation on P84/NCC-based tubular carbon membrane under different carbonization conditions

In this study, the influence of carbonization environment on the performance of Tubular Carbon Membrane (TCMs) was explored. P84 co-polyimide/Nanocrystalline cellulose-based TCMs were synthesized by dip-coating technique. The permeation properties of TCMs were determined by employing pure gas of CO2 and N2. Heat treatment processes were carried out under different environment (Argon, Nitrogen, and Helium) with the flow rate of 200 ml/min to boost the membrane’s performance. The carbonization process was performed at a consistent carbonization temperature of 800oC under heating rate of 3oC/min. Carbonization under Argon environment was found to be the best condition for PI/NCC-based TCMs preparation with the permeance of 3.22±3.21and 213.56±2.17 GPU for N2, and CO2 gases, respectively. This membrane exhibited the uppermost CO2/N2 selectivity of 66.32±2.18. TCMs prepared under Ar environment experienced less weight loss while exhibiting highest CO2/N2 selectivity as compared to those prepared under He and N2 environment.

Novel Tubular Carbon Membranes Prepared from Natural Rattans

The novel tubular carbon membranes produced from natural materials are, for the first time, reported. The novelty of this idea is to use natural rattans as precursors for making carbon membranes to address the challenges of cellulose polymers. The rattan precursors were carbonized to present evenly distributed channels inside the tubular carbon membranes. Each channel has an inner diameter of 2 × 10−4 m with a dense-selective inner layer and a porous outer layer. Future work on selection of suitable rattans, proper pre-treatment, carbon structure tailoring can be conducted to open a new research field of carbon membranes/materials.

P84 Co-Polyimide-based Tubular Carbon Membrane: Effect of Pyrolysis Temperature

In this study, the effect of carbonization temperature on the performance of carbon membrane was being investigated. P84 co-polyimide-based tubular carbon membrane were fabricated through the dip-coating technique. The prepared membranes were characterized by using the thermogravimetric analysis and scanning electron microscopy. CO2, N2, and CH4 pure gas were utilized in determination of the carbon membrane’s permeation attributes. In order to enhance the membrane’s performance, carbonization process was performed in Ar environment; with the flow rate of 200 ml/min. The carbonization process was done at various temperature, namely 600 oC, 700 oC, 800 oC and 900 oC in a constant heating rate of 3 oC/min. The increased in the temperature of carbonization leads to the production of small pores size carbon membrane. Carbon membrane prepared at 800 oC showed the highest CO2/CH4 and CO2/N2 selectivity of 63.2±5.2 and 61.3±1.7, respectively.

Effect of heating rates on the microstructure and gas permeation properties of carbon membranes

High performance tubular carbon membrane (TCM’s) for CO2 separation were prepared by controlling the carbonization heating rates in range of 1-7 oC/min carbonized at 800 oC under Argon environment. A single permeation apparatus was used to determine the gas permeation properties of the membrane at room temperature. Fine turning of the carbonization condition was necessary to obtain the desired permeation properties. The preparation of PI/NCC-based TCM at low heating rate caused the gas permeance for the examined gas N2 and CO2 decreased whereas the selectivity of CO2/N2 increased. It was also identified that the gas permeation properties of the resultant TCM and its structure was highly affected by the heating rate. The best carbonization heating rate was found at 3oC/min for the fabrication of TCM derived via polymer blending of PI/NCC for CO2/N2 separation.

CO2 Selective Carbon Tubular Membrane: The Effect of Stabilization Temperature on BTDA-TDI/MDI P84 co-polyimide

Membranes offer remarkable attributes such as possessing small equipment footprints, having high efficiency and are environmentally friendly, with carbon membranes progressively investigated for gas separation applications. In this study, carbon tubular membranes for CO2 separationare prepared via the dip-coating method with P84 co-polyimide as the carbon precursor. The prepared membranes were characterized using Thermogravimetric Analysis (TGA), pore structure analysis Brunauer-Emmett-Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR) and pure gas permeation system. The permeation properties of the carbon membranes are measured and analyzed by using CO2, CH4 and N2 gases. The P84-based carbon tubular membrane stabilized at 300°C and featured excellent permeation properties with permeance range of 2.97±2.18, 3.12±4.32 and 206.09±3.24 GPU for CH4, N2 and CO2 gases, respectively. This membrane exhibited the highest CO2/CH4 and CO2/N2 selectivity of 69.48±1.83 and 65.97±2.87, respectively.