Concentration Of Coating Solution Research Articles

Investigating the Influence of Additive Manufacturing and Ultrasonic Coating Parameters on Biopolymeric Scaffold Performance Using Response Surface Methodology.

Triply periodic minimal surface (TPMS) scaffolds have gained attention in additive manufacturing due to their unique porous structures, which are useful in biomedical applications. Unlike metallic implants that can cause stress shielding, polymeric scaffolds offer a safer alternative. This study is focused on enhancing the compressive strength of additive-manufactured polylactic acid (PLA) scaffolds with a diamond structure. The response surface methodology (RSM)-based experimental design was developed to study the influence of printing parameters. The fused deposition modeling (FDM) process parameters were optimized, achieving a compressive strength of 56.2 MPa. Subsequently, the scaffolds were fabricated at optimized parameters and underwent ultrasonic-assisted polydopamine coating. With the utilization of the RSM approach, the study examined the effects of ultrasonic vibration power, coating solution concentration, and submersion time on compressive strength. The optimal coating conditions led to a maximum compressive strength of 92.77 MPa-a 65.1% improvement over the uncoated scaffold. This enhancement is attributed to the scaffold's porous structure, which enables uniform coating deposition. Energy-dispersive x-ray spectroscopy confirmed the successful polydopamine coating, with 10.64 wt% nitrogen content. These findings demonstrate the potential of ultrasonic-assisted coating in improving the mechanical properties of PLA scaffolds, making them suitable for biomedical applications.

Experimental investigation of ultrasonic assisted coating on three-point bending behavior of 3D printed polymeric bone plates for biomedical applications

3D printed Poly Lactic Acid (PLA) bone plates exhibit limited three-point bending strength, restricting their viability in biomedical applications. The application of polydopamine (PDM) enhances the three-point bending strength by undergoing covalent interactions with PLA molecular structure. However, the heavy nature of PDM particles leads to settling at the container base at higher coating solution concentrations. This study investigates the impact of ultrasonic-assisted coating parameters on the three-point bending strength. Utilizing Response Surface Methodology (RSM) for statistical modeling, the study examines the influence of ultrasonic vibration power (UP), coating solution concentration (CC), and submersion time (TIME). RSM optimization recommended 100 % UP, 6 mg/ml CC, and 150 min TIME, resulting in maximum three-point bending strength of 83.295 MPa. Microscopic images from the comparative analysis revealed non-uniform coating deposition with mean thickness of 6.153 µm under normal coating. In contrast, ultrasonic-assisted coating promoted uniform deposition with mean thickness of 18.05 µm. The results demonstrate that ultrasonic-assisted coating induces PDM particle collision, preventing settling at the container base, and enhances three-point bending strength by 7.27 % to 23.24 % compared to the normal coating condition. This study emphasizes on the potential of ultrasonic-assisted coating to overcome the limitations of direct immersion coating technique.

Response surface methodology and machine learning based tensile strength prediction in ultrasonic assisted coating of poly lactic acid bone plates manufactured using fused deposition modeling

Poly Lactic Acid (PLA) based bone plates fabricated using Fused Deposition Modeling have poor mechanical strength which can be improved by biocompatible polydopamine (PDM) coating. However, PDM particles, being heavy in nature, settle at the container bottom with increase in coating solution concentration at the time of bone plate coating using dip coating technique. Thus, the present work aims to witness the effect of ultrasonic assisted coating parameters on tensile strength of coated bone plates. The coating parameters involving power of ultrasonic vibrations, coating solution concentration and immersion time were varied. The standard Response Surface Methodology (RSM) was applied and experimental trials were performed for obtaining tensile strength of bone plates under varied coating parameters. The objective of the present study was to compare the values of tensile strength predicted using RSM and machine learning (ML) models. Based on the obtained experimental values, gradient boosting regression (GBReg), linear regression (LReg) and random forest regression (RFReg) were trained and tested for predicting tensile strength of bone plates. The accuracy and prediction errors corresponding to RSM and ML based models were compared with respect to R2, Mean Squared Error (MSE), Mean Absolute Error (MAE) and Root Mean Squared Error (RMSE). The findings revealed that GBReg exhibited R2, MSE, RMSE and MAE values as 0.9312, 1.7142, 1.2877 and 1.0861 respectively, while RSM showed R2, MSE, RMSE and MAE values as 0.882, 2.13, 1.4595 and 1.258 respectively. RSM model has shown minimum accuracy with high prediction errors amongst the four models. GBReg has outperformed other ML models in terms of their accuracy and error metrics. The present study therefore suggests the application of GBReg based ML model for predicting tensile strength of PDM coated bone plates in response to its accurate and robust prediction performance.

Optimization of polydopamine coating process for poly lactic acid‐based 3D printed bone plates using machine learning approaches

AbstractThe three‐dimensional (3D) printed poly lactic acid (PLA) bone plates lack mechanical strength, resulting in premature failure. Coating these plates with polydopamine (PDM) forms covalent bonds with the PLA molecular structure, enhancing their mechanical properties. The mechanical strength of the coated bone plates is influenced by infill density, submersion time, shaker speed, and coating solution concentration. However, conducting experiments for each parameter value to achieve maximum biomechanical tensile strength (BTS) and biomechanical flexural strength (BFS) is time‐consuming and costly. Overall, the combination of response surface methodology (RSM) and machine learning (ML) enables determination of the best printing parameters, leading to reduced material waste, personalized bone plates tailored to individual anatomy, improved implant fit, and functionality. Moreover, this approach has the potential to reduce the need for additional surgeries and overall costs. To optimize coating parameters, this study employs RSM and ML techniques, including genetic algorithm (GA), particle swarm optimization (PSO), random search optimization (RSO), and differential evolution (DE). Experimental validation of the optimized process parameters and their corresponding fitness values is carried out using both RSM and ML approaches. The results demonstrate that GA has the closest relationship between experimental and fitness values, followed by DE, RSM, PSO, and RSO.Highlights Direct immersion coating of polydopamine on 3D printed PLA bone plates. Evaluating mechanical strength for bone plates coated at varying parameters. Statistical modeling and optimization of mechanical strength using RSM. Mechanical strength optimization and convergence properties for ML models. Experimental validation of RSM and ML‐based optimization algorithms.

Polydopamine and d-tyrosine-functionalized PTFE membrane for membrane distillation of secondary effluent: Fouling mitigation and mechanism

Secondary effluent from municipal wastewater treatment plants can be used to produce reclaimed water through membrane distillation (MD), providing a potential solution to the current global water crisis. However, membrane fouling over extended periods of operation reduces the separation performance of MD systems and significantly shortens the operational life-span of the membrane. Herein, in order to overcome these limitations, a novel surface-modified PTFE membrane was fabricated by depositing polydopamine and grafting dextro (d)-tyrosine (Tyr/PDA@PTFE). This synergistic coating was designed to reduce surface hydrophobicity of the PTFE membrane and provide anti-adhesive properties for bacteria, while enhancing flux and anti-fouling performance during MD. The Tyr/PDA@PTFE membranes demonstrated enhanced MD performance and the Tyr-300/PDA@PTFE membrane (with d-tyrosine coating solution concentration of 300 μM) exhibited the best MD performance during direct contact membrane distillation (DCMD) of the secondary effluent, with the highest flux (49.1 LMH) compared with the pristine PTFE membrane (34.7 LMH), achieving a flux increase of 41.5%. Long-term DCMD operation showed that the Tyr-300/PDA@PTFE membrane exhibited improved anti-fouling performance compared with the pristine PTFE membrane, with 43.8% flux decay observed after three cycles of use, while the pristine PTFE membrane was unable to complete three cycles of use with an 87.2% decrease in flux observed by middle of the third round. The quality of permeate formed by the Tyr/PDA@PTFE membranes during MD, indicated that they could be operated stably for three cycles of use over a 40 h period, intercepting organic matter in the feed solution. The Tyr-300/PDA@PTFE membrane was especially effective for the removal of low molecular weight and humus-like substances, achieving rejection rates of 89.5% and 86.7%, respectively. Additionally, the Tyr/PDA@PTFE membrane carried the more negative charge and exhibited a high level of resistance to bio-adhesion. This study demonstrates the feasibility of use of this novel Tyr/PDA@PTFE membrane in MD, for the effective treatment of secondary effluent from wastewater treatment plants and the production of reclaimed water.

Predicting biomechanical properties of additively manufactured polydopamine coated poly lactic acid bone plates using deep learning

Fused Filament Fabrication based bone plates lack mechanical strength, resulting in premature failure. Biocompatible Polydopamine (PDM) coating forms covalent bonds with Poly Lactic Acid (PLA), resulting in enhanced mechanical characteristics. Infill density, submersion time, shaker speed, and coating solution concentration, have a significant effect on the mechanical properties of coated bone plates. Monitoring the mechanical strength experimentally for each set of process parameters is a time-consuming and tedious procedure. Before resorting to experimental tests, it is important to model and predict the mechanical strength in order to increase the mechanical strength of bone plates. Predictive modeling using machine learning approaches has proven to be the best alternative to traditional statistical tools. In this study, various machine learning algorithms, including Random Forest, k-Nearest Neighbors, AdaBoost, and Decision Trees, and Long Short-Term Memory (LSTM) method, were utilized to predict tensile and flexural strengths. Error metrics consisting of Mean Square Error (MSE), Root Mean Square Error (RMSE), Correlation Coefficient (R2), Mean Absolute Percentage Error (MAPE) and RRMSE (Root Relative Mean Squared Error) have been utilized to assess the performance of various models. Owing to the prediction findings, the LSTM model beat all ML-based models by demonstrating the best MSE, RMSE, and R2 values for tensile and flexural strength, which were 5.96 MPa, 2.44 MPa, and 0.9169, respectively, and 11.14 MPa, 3.34 MPa, and 0.9242, respectively. Consequently, the results of this study suggest that LSTM is the best model for predicting the tensile and flexural strength of PDM-coated PLA bone plates without doing experiments.

Surface synthesis of a polyethylene glutaraldehyde coating for improving the oil removal from wastewater of microfiltration carbon membranes

Development of hydrophilic microfiltration carbon membrane (MFCM) is essential for improving the separation performance of oil-water emulsion. In this work, a strategy was proposed to modify the microstructure and property of MFCM by surface synthesizing a hydrophilic polyethylene glutaraldehyde (PVG) coating. The thermal stability, functional groups, morphology and porous structure of modified MFCM were characterized by thermogravimetric analyzer, Fourier transform infrared spectroscopy, scanning electron microscope and general weight difference/filtration velocity techniques, respectively. The effects of coating types, coating solution concentration on the structure and separation performance of MFCM for oily wastewater were investigated. The results showed that the surface PVG coating was sufficiently stable to resist the aggressive system of oily wastewater. Both water permeation flux and oil rejection were significantly improved for MFCM after modification. Moreover, the water permeation flux and oil rejection of MFCM respectively decreased and increased as the concentration of coating solution was increased. The maximum oil rejection reached to 94.8% for MFCM modified with a PVG surface layer formed by coating a starting solution of 9%, along with a permeation flux of 691.1 kg/m2 h MPa.

Interrelationships Between Coating Uniformity and Efficiency in Pan Coating Processes.

The relationships between coating uniformity and efficiency were explored for tablet coating processes in pan coaters. The factors affecting the size of the spray zone were modeled using one-dimensional deposition analysis of spray droplets. This model was incorporated into the analytical model developed for coating uniformity by Choi et al. (AAPS PharmSciTech 22(7), 2021) that farther elucidated the effects of tablet shape and bed porosity. The results were compared with literature data on coating efficiency. The variables examined included tablet shape and size, coating time, pan speed, atomizing and pattern air flow rates, bed porosity, spray rate, batch size, coating solution concentration, spray gun-to-bed distance, and pan diameter. It is shown that, except for pan diameter and atomizing air flow rate, variables that improve coating efficiency adversely affected coating uniformity and vice versa. Implications of these relationships are discussed to improve formulation, process, and equipment designs.

Evolution of Surface Morphology of Spin-Coated Poly(methyl methacrylate) Thin Films.

The morphology of sub-micron poly(methyl methacrylate) films coated to glass supports by spin coating from toluene is examined using surface profilometry. Wrinkled surfaces with local quasi-sinusoidal periodicity were seen on the surfaces of films with thicknesses of larger than 75 nm. The surface wrinkles had large aspect ratios with wavelengths in the tens of microns and amplitudes in the tens of nanometers. Wrinkles that formed during spin-coating are attributed to surface perturbations caused by Rayleigh–Bénard–Marangoni convective instabilities. The effects of film thickness, coating solution concentration, and drying rate on the thin film surface morphology are investigated. The results can be used to prepare surfaces with controlled morphology, either smooth or with periodic wrinkles.

A facile route to insulate an Fe-based nanocrystalline alloy powder for magnetic composite cores

We tested a facile surface coating procedure using 3-aminopropyltriethoxysilane (APTES) as a coating reagent to insulate the surface of Vitroperm 800. Both Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) confirmed the presence of iron oxides on the surface of the Vitroperm. The higher oxidation state of Fe3+ (Fe2O3) was preferably formed over the Fe2+ state (Fe3O4) when the organosilane concentration was increased. XPS revealed that a coating solution concentration >5 mM was required to obtain an insulating silicon oxide layer similar to SiO2. The presence of these oxides on the surface of Vitroperm elevated the surface resistivity into the 106 Ω-cm range without having a detrimental impact on the direct current (DC) magnetic flux density or alternating current (AC) permeability. The insulating coating slightly decreased the DC coercivity, which is related to hysteresis loss. However, the increase in surface resistivity should decrease eddy current losses.

Fabrication and Characterization of Composite Membranes for the Concentration of Lithium Containing Solutions Using Forward Osmosis

AbstractIn this study, an energy and highly time efficient, cost effective, and scalable forward osmosis (FO) composite polyvinylidene fluoride (PVDF) membrane is developed to concentrate lithium chloride recovered from naturally occurring geothermal brine resources. Dense thin robust defect‐free Kynar‐PVDF membranes are fabricated on porous PVDF hollow fiber supports. Various membrane fabrication parameters such as membrane thickness, coating solution concentration, cross‐linker concentration, and curing temperature are studied to develop a defect‐free dense membrane. Advanced characterization tools such as FIB‐SEM, Raman, FTIR spectroscopy, and XRD are used to study the surface and cross‐sectional morphology, chemistry of crosslinking, crystallinity and chemical structure of the dense PVDF membrane. FO is utilized to concentrate LiCl in the solution from 36 to 175 g L−1 with an average water transfer rate of 0.450 L m−2 h−1 (LMH) at 85 °C. Furthermore, the membrane showed stable performance for more than 550 h while maintaining the purity of the concentrated lithium chloride solution of >99.99 wt%. The results suggest that the FO‐based technology is an innovative, time and energy efficient approach compared to the conventional technologies for concentration of battery grade LiCl for application in lithium ion batteries and other clean energy technologies.

Shedding light on coatings: Real-time monitoring of coating quality at industrial scale

Optical Coherence Tomography (OCT) is increasingly being used for studies of pharmaceutical film coating. OCT allows fast and non-destructive analysis of the coating thickness and quality via high-resolution cross-sectional images. Information about both the coating thickness and the coating quality can be extracted. Most studies and OCT applications performed to date have been limited to off-line measurements and off-line computations of coating features based on data acquired in-line. This study examines OCT’s applicability to an industrial-scale pan coating process. Automated layer detection, classification and thickness calculation were executed in real time. To evaluate the system’s performance, runs with various tablet size, coating solution concentration and operating parameters were carried out and monitored. Our results indicate that, in addition to correct end-point determination, OCT enables real-time monitoring of the coating processes (thickness, homogeneity and roughness) and can support active process control by supplying information about the coating thickness and quality.

بررسی اثرتعداد لایهها و غلظتهای مختف پوششهای خوراکی کربوکسیمتیلسلولز و کاراگینان بر کارایی فرایند خشک کردن اسمزی سیب زرد لبنانی

در طی فرایند آبگیری اسمز، مواد جامد محلول توسط بافت ماده غذایی جذب شده و اثرات نامطلوبی بر خروج آب، خصوصیات تغذیه‌ای و حسی می‌گذارد. لذا برای بهبود فرایند اسمز از پوشش‌های خوراکی استفاده می‌شود. بهترین شاخص برای ارزیابی یک پوشش، کارایی فرایند (نسبت خروج آب به جذب مواد جامد) است. در این پژوهش از دو پوشش کربوکسی‌متیل‌سلولز و کاراگینان در سه غلظت 5/0، 1 و 5/1 درصد، به‌صورت یک‌لایه و دو لایه، جهت پوشش‌دهی قطعات مکعبی سیب زرد لبنانی و محلول اسمزی ساکارز با غلظت 30، 45 و 60 % استفاده شد. نتایج نشان داد که نمونه یک بار پوشش داده شده با کاراگینان 1% و تیمار شده در ساکارز 60 % و نمونه‌های یک و دو لایه پوشش داده شده با کربوکسی‌متیل‌سلولز 5/0% بیشترین میزان کارایی فرایند را داشته‌اند و به‌عنوان تیمارهای برگزیده به‌دست آمدند. این نمونه‌ها میزان جذب مواد جامد را کاهش داده و تاثیر قابل توجهی بر روی خروج آب نگذاشته‌اند. همچنین نتایج بیان‌گر این موضوع است که با افزایش غلظت محلول اسمزی ساکارز از 30 به 60% میزان حذف آب و جذب مواد جامد افزایش می‌یابد.

Solidification of cinnarizine self-nanoemulsifying drug delivery systems by fluid bed coating: optimization of the process and formulation variables.

Self-nanoemulsifying drug delivery systems (SNEDDS) offer an efficient choice to improve the poor dissolution and erratic bioavailability of poorly-water soluble drugs. However, liquid SNEDDS experience some manufacturing and stability limitations. To overcome these limitations, the current study aims to investigate and optimize the solidification of cinnarizine (CN) liquid SNEDDS onto pellets by fluid bed coating. The study involved optimization of process and formulation variables. The coated self-nanoemulsifying pellets (SNEP) were characterized, their droplet size and dissolution profiles were compared to the corresponding liquid SNEDDS. Higher spray/microclimate air pressure led to minimal agglomeration and minimal spray drying. However, slight increase in inlet air volume above 35 m3/h led to extensive spray drying. The optimized coating formula included oleic acid/Imwitor308/Cremophor El (25/25/50) as liquid SNEDDS, HPMC E3 as coating polymer and Plasacryl™T20 as anti-tacking agent. The optimum concentration of coating solution was 15% and optimum SNEDDS proportion in the coating layer was 40%. The droplet size of reconstituted SNEP was significantly (p < 0.05) higher than liquid SNEDDS, yet the SNEP aqueous dispersion was still within the nano-metric scale. Pure CN showed sharp precipitation upon shifting the media from pH 1.2 to 6.8. In contrast, Both SNEP and liquid SNEDDS maintained >85% CN in solution, even at pH 6.8. Therefore, CN-SNEP seems to be an excellent dosage form that maintains the solubilization benefits of liquid SNEDDS, overcomes their limitations along with the additional benefits of solid dosage form.

FTIR mapping as a simple and powerful approach to study membrane coating and fouling

The purpose of this work is to apply FTIR mapping to the analysis of the coating and fouling behaviour of PVDF membranes coated with two different types of PS-PEGMA copolymers – diblock and random. The coating conditions involve the variation of coating solution concentration and of coating time. We have carried out adsorption experiments with BSA as the foulant, and also filtration experiments. The analysis of the results is mainly performed by image analysis of the mapped surfaces with two approaches: taking the average grey value/peak height of the whole surface for the coating and foulant signals, and by defining coating/fouling levels as an initial approach to analyse heterogeneity. Our results show that there is an heterogeneous distribution of the coating and fouling layers on the membrane surface at a millimetre scale. Moreover, the diblock copolymer has a slightly better anti-adsorption performance than the random one. Coating conditions should be carefully chosen and conclusions regarding the anti-fouling properties of the membranes should be drawn by taking into account both adsorption and filtration tests. All in all, FTIR mapping is a technique that should be taken into account for the study of fouling phenomena.

Influence of polydopamine deposition conditions on hydraulic permeability, sieving coefficients, pore size and pore size distribution for a polysulfone ultrafiltration membrane

Membrane surface modification with polydopamine (PDA) coatings can reduce fouling in oily water filtration due, at least in part, to enhanced surface hydrophilicity. In this study, polysulfone (PSf) UF membranes were coated with PDA. PDA coating conditions (solution concentration and deposition time) were varied, and the effect of coating conditions on membrane molecular weight cutoff (MWCO) and hydraulic permeability was measured. Membrane MWCO decreased and PDA film thickness increased as initial dopamine coating solution concentration or deposition time increased. The MWCO decrease confirmed that PDA restricted the membrane pores. While the PDA coating thickness on membrane surfaces grew progressively with increasing initial dopamine concentration or coating time, coating inside the membrane pores was limited by the finite membrane pore size. A tradeoff between selectivity and hydraulic permeability of unmodified and PDA-modified membranes was noted. This tradeoff is reminiscent of that observed in other separation membranes. Zydney’s hindered solute transport model of flow through porous membranes was used to estimate changes in membrane mean pore size and pore size distribution. Based on the modelling results, membrane mean pore radius increased at low initial dopamine concentrations or short deposition times and decreased at high initial dopamine concentrations or long deposition times with increasing initial dopamine concentration or increasing PDA coating time. The pore size distribution narrowed as the membranes were modified with PDA. The porosity to thickness ratio of PDA-modified membranes remained unchanged or was only slightly higher than that of unmodified membranes.

A Simple and Rapid Method for Preparing Carbon Nanopore Electrode Ensemble (CNEE) by Coating A Commercial Glassy Carbon (GC) Electrode with Chromate

A simple preparation method for carbon nanopore electrode ensemble (CNEE) was reported. The CNEE consists of a number of pinholes which remain after coating a carbon surface with chromate. The transformation from transient to steady-state voltammetric behavior of carbon surface was presented. The effect of electrochemical technique to structure of chromate film was investigated. The optimum deposition time and optimum concentration of chromate solution for coating carbon surface substantially were determined for bulk electrolysis (BE) technique. On the other hand for cyclic voltammetry (CV), the effects of scan rate, number of cycle and coating solution concentration on forming uniform partly-insulating layer have been examined. The CNEE prepared by BE technique showed larger hysteresis which means more resistivity than the one prepared by CV. Under the optimum coating conditions the thinner and more useful CNEE with lower resistivity can be prepared by CV. Keywords: Carbon nanopore electrode ensemble (CNEE); chromate; steady-state current; radial diffusion; microelectrode DOI: 10.17350/HJSE19030000025 Full Text:

Preparation of Chitosan-Alginate/PES Pervaporation Membranes for Bioethanol Dehydration

In the last decade pervaporation membrane has become an antractive dehydration processs for azeotropic ethanol-water mixture. In this paper, chitosan-alginate/polyethersulfone (PES) composite membranes were prepared (by coating method) characterized as pervaporation membranes. The composite membranes were then examined to purify ethanol-water mixture. The characterization included degree of swelling both in water and ethanol, permeability measurement, surface morphology (by SEM) and surface chemistry (by FTIR). The results show that the increase in concentration of coating solution increases the degree of swelling in the water on the one hand, whereas the permeability and the degree of swelling in the ethanol decreases on the other hand. The highest permeability was obtained for the composite membrane prepared from a coating solution concentration of 1% with the ratio of chitosan to alginate was 0,33. The surface chemistry shows that the increase in concentration of chitosan - alginate solution increases the intensity of a specific wave number of C-O and C-N groups. Surface morphology indicates that the PES membrane surface is clearly covered by chitosan - alginate mixture. Performance examination demonstrates that the composite membrane prepared by 3% a coating solution (with the ratio of chitosan to alginate 3) can increase the bioethanol concentration from 95.5% to 99.6%.

Influence of coating conditions on the H2 separation performance from H2/CH4 gas mixtures by the PDMS/PEI composite membrane

In the present study, the composite polyetherimide (PEI) membrane coated with poly dimethyl siloxane (PDMS) was synthesized and optimum conditions of coating were obtained for separation of hydrogen from methane. Three coating techniques “pouring solution inclined by 45°”, “film casting” and “dip-coating” were used. The effect of sequential coating for different methods on permselectivity of the membranes was investigated. In addition, the influences of coating conditions including coating solution concentration, coating and curing temperatures were examined. The results showed that when the concentration of PDMS coating solution was increased; the permeance of H2 was initially declined rapidly and was then gradually leveled off. The optimum concentration of coating solution was 15 wt.%. The examination of the curing and coating temperatures showed no significant effect on H2 permeance and selectivity. In the “dip coating” method, two times coating showed superior permeance and selectivity and in “film casting”, the performance of triple coating was promising. Higher selectivities for the composite membrane prepared by “dip-coating” introduced this method as the best method. The sequential dip-coating with different PDMS concentrations was applied and the selectivity was enhanced significantly from 26 to 96 for pure gases and from 22 to 70 for the binary gas mixture. Finally, the influence of pressure on the separation performance of the fabricated membrane was investigated.

High performance composite hollow fiber membranes for CO2/H2 and CO2/N2 separation

The search for a clean energy source as well as the reduction of CO2 emissions to the atmosphere are important strategies to resolve the current energy shortage and global warming issues. We have demonstrated, for the first time, a Pebax/poly(dimethylsiloxane)/polyacrylonitrile (Pebax/PDMS/PAN) composite hollow fiber membrane not only can be used for flue gas treatment but also for hydrogen purification. The composite membranes display attractive gas separation performance with a CO2 permeance of 481.5 GPU, CO2/H2 and CO2/N2 selectivity of 8.1 and 42.0, respectively. Minimizing the solution intrusion using the PDMS gutter layer is the key to achieving the high gas permeance while the interaction between poly(ethylene oxide) (PEO) and CO2 accounts for the high selectivity. Effects of coating solution concentration and coating time on gas separation performance have been investigated and the results have been optimized. To the best of our knowledge, this is the first polymeric composite hollow fiber membrane for hydrogen purification. The attractive gas separation performance of the newly developed membranes may indicate good potential for industrial applications.