Selection Of Membrane Material Research Articles

Gate-All-Around Nanopore Osmotic Power Generators.

Nanofluidic channels in a membrane represent a promising avenue for harnessing blue energy from salinity gradients, relying on permselectivity as a pivotal characteristic crucial for inducing electricity through diffusive ion transport. Surface charge emerges as a central player in the osmotic energy conversion process, emphasizing the critical significance of a judicious selection of membrane materials to achieve optimal ion permeability and selectivity within specific channel dimensions. Alternatively, here we report a field-effect approach for in situ manipulation of the ion selectivity in a nanopore. Application of voltage to a surround-gate electrode allows precise adjustment of the surface charge density at the pore wall. Leveraging the gating control, we demonstrate permselectivity turnover to enhanced cation selective transport in multipore membranes, resulting in a 6-fold increase in the energy conversion efficiency with a power density of 15 W/m2 under a salinity gradient. These findings not only advance our fundamental understanding of ion transport in nanochannels but also provide a scalable and efficient strategy for nanoporous membrane osmotic power generation.

Analytical Analysis of Flexible Microfluidic Based Pressure Sensor Based on Triple-Channel Design

In designing a flexible microfluidic-based pressure sensor, the microchannel plays an important role in maximizing the sensor's performance. Similarly, the material used for the sensor's membrane is crucial in achieving optimal performance. This study presents an analytical analysis and FEA simulation of the membrane and microchannel of the flexible pressure sensor, aimed at optimizing it design and material selection. Different types of materials, including two commonly used polymers, Polyimide (PI) and Polydimethylsiloxane (PDMS) were evaluated. Moreover, different designs of the microchannel, including single-channel, double-channel, and triple-channel, were analyzed. The applied pressure, width of the microchannel, and length of the microchannel were varied to study the normalized resistance of the microchannel and maximize the performance of the pressure sensor. The results showed that the triple-channel design produced the highest normalized resistance. To achieve maximum performance, it is found that using a membrane with a large area facing the applied pressure was optimal in terms of dimensions. In conclusion, optimizing the microchannel and membrane design and material selection is crucial in improving the overall performance of flexible microfluidic-based pressure sensors.

Experimental Investigation of the Desalination Process for Direct Contact Membrane Distillation Using Plate and Frame Membrane Module

Through experiments, the effect of membrane material selection and operating conditions on permeate fluxes in direct contact membrane distillation (DCMD) desalination was investigated. The experiment used a plate and frame membrane module, and with nine different hydrophobic porous membranes, a comparative analysis of the desalination performance of 3 wt% NaCl solution was performed. The results of this experiment were compared to find out the effect of different materials, pore sizes and membrane thicknesses on the permeate flux under same operating conditions. Further, a three-factor, three-level orthogonal experiment was designed. The effects of hot-side temperature, hot-side inlet flow and cold-side inlet flow on the permeate flux of PTFE membranes with a pore size of 0.22 μm were investigated when the temperature on the cold side was set at 20 °C. The results showed that in the DCMD experiments, both PTFE and PVDF membranes performed well, and that hot-side inlet temperatures and cold-side inlet flow rates had significant effects on the permeate flux.

Fabrication of a novel hollow wood fiber membrane decorated with halloysite and metal-organic frameworks nanoparticles for sustainable water treatment

Membrane separation techniques have been proven to be highly efficient for the treatment of organic wastewater. The selection of membrane material is crucial for achieving high-efficiency water treatment and promoting large-scale application. In this work, a novel membrane (Fiber/HNTs/ZIF-67) was fabricated by combining hollow wood fiber (Fiber), halloysite nanotubes (HNTs), and metal-organic frameworks nanoparticles (ZIF-67) via acrylamide crosslinking. Hollow wood fiber served as main skeleton of the membrane, while HNTs and ZIF-67 nanoparticles acted as filling materials to adjust membrane’s pore structure and enhance the adsorption capacity. Meanwhile, ZIF-67 nanoparticles endow the membrane with peroxymonosulfate activation for the degradation of organic dyestuff. Additionally, the hollow and porous structures of wood fiber and HNTs as well as the porosity generated from the acrylamide crosslinking process facilitate rapid water transmission channels in water treatment. The Fiber/HNTs/ZIF-67 membrane displays high flux of 209 L·(m2·h)−1 with 100% rejection rate for methylene blue solution. Moreover, the designed membrane with catalytic activity of ZIF-67 demonstrates impressive decontaminated and recycling ability. Besides, the composite of wood fiber and inorganic nanomaterials ensure excellent mechanical properties and thermal stability. The fabrication of Fiber/HNTs/ZIF-67 is simple, and it exhibits excellent water treatment capacity. These promising results position it as a practical solution for the treatment of organic wastewater.

Polymer materials for solving actual problems of membrane gas

Membrane gas separation using polymeric membranes is one of rapidly developing energy-conserving technologies. This review describes the scope of membrane gas separation problems and demonstrates the relevance of membrane methods for their solution. The basic concepts and regularities of diffusion gas transfer and principles and characteristics of membrane gas separation are considered. The main physicochemical approaches to the selection of membrane materials considering both the properties of the gas–polymer system and the structure and physical properties of polymers are discussed. The considered issues are combined within a common approach to substantiate the choice of both existing commercial polymers and advanced polymeric materials to address important gas separation problems such as separation of air components; carbon dioxide, hydrogen and helium recovery from natural and industrial gas mixtures; and separation of a nitrogen and methane mixture. The avenues of development of the membrane materials science to solve each of the mentioned problems of membrane gas separation are demonstrated. The review is intended for specialists in the synthesis and physics of polymers for planning the research and assessing the applicability of polymeric materials for various practical gas separation problems and for specialists in the membrane materials science and membrane technology. <br> The bibliography includes 165 references.

Integrated membrane material design and system synthesis

In designing membrane systems, the synergy between membrane materials and the process design is often overlooked. We present a mixed-integer nonlinear programming (MINLP) model for synthesizing membrane systems while simultaneously designing the respective membrane materials for multicomponent gas separation. The approach considers superstructure representations for systems with: (1) same, (2) potentially different, and (3) property-targeting membrane materials. In the first two systems, the selection of membrane material is a decision, while in the final type, membrane permeances are subject to optimization. Physics-based surrogate models are used to describe permeation in crossflow and countercurrent flow permeators. We show that, through a case study of biogas upgrading, our approach obtains high quality solutions. Furthermore, we use the proposed approach while considering permeance-based production cost to find the optimal membrane.

Prediction of organic contaminant rejection by nanofiltration and reverse osmosis membranes using interpretable machine learning models.

Efficiency improvement in contaminant removal by nanofiltration (NF) and reverse osmosis (RO) membranes is a multidimensional process involving membrane material selection and experimental condition optimization. It is unrealistic to explore the contributions of diverse influencing factors to the removal rate by trial-and-error experimentation. However, the advanced machine learning (ML) method is a powerful tool to simulate this complex decision-making process. Here, 4 traditional learning algorithms (MLR, SVM, ANN, kNN) and 4 ensemble learning algorithms (RF, GBDT, XGBoost, LightGBM) were applied to predict the removal efficiency of contaminants. Results reported here demonstrate that ensemble models showed significantly better predictive performance than traditional models. More importantly, this study achieved a compelling tradeoff between accuracy and interpretability for ensemble models with an effective model interpretation approach, which revealed the mutual interaction mechanism between the membrane material, contaminants and experimental conditions in membrane separation. Additionally, feature selection was for the first time achieved based on the aforementioned model interpretation method to determine the most important variable influencing the contaminant removal rate. Ultimately, the four ensemble models retrained by the selected variables achieved distinguished prediction performance (R2adj = 92.4 %-99.5 %). MWCO (membrane molecular weight cut-off), McGowan volume of solute (V) and molecular weight (MW) of the compound were demonstrated to be the most important influencing factors in contaminant removal by the NF and RO processes. Overall, the proposed methods in this study can facilitate versatile complex decision-making processes in the environmental field, particularly in contaminant removal by advanced physicochemical separation processes.

A comprehensive study on the ionomer properties of PFSA membranes with confocal Raman microscopy

The proton exchange membrane is the heart of many electrochemical energy systems, and their performance and longevity depend on a careful selection and processing of membrane materials. In this work, we use confocal Raman microscopy to investigate application-relevant properties of perfluorinated sulfonic acid (PFSA) membranes. Raman spectra of Nafion, Aquivion, and 3M Ionomer at different equivalent weights show differences in the spectral area and position of various Raman bands but reveal a clear trend of band intensities versus equivalent weight. Characteristics of these ionomers such as swelling and water uptake were determined with through-plane imaging. The technique offers advantages over conventional measurements, such as contact-free and non-destructive data acquisition. Calibration curves for the equivalent weight were derived for the different PFSAs with excellent linear fits that allow a quantification of the ionizable group content. The high spatial resolution of confocal Raman microscopy of less than 2 μm enables the local evaluation of all these ionomer properties. Furthermore, Raman imaging was employed to characterize composite membranes, which shows that it can resolve individual phases and features in multi-layered membranes. This study provides a comprehensive summary of confocal Raman microscopy as a powerful tool for the analysis of ionomer and membrane properties.

A Review on Hollow Fiber Membrane Contactors for Carbon Capture: Recent Advances and Future Challenges

Energy need is predicted to increase by 48% in the next 30 years. Global warming resulting from the continuously increasing atmospheric CO2 concentration is becoming a serious and pressing issue that needs to be controlled. CO2 capture and storage/use (CCS/CCU) provide a promising route to mitigate the environmental consequences of CO2 emission from fossil fuel combustion. In recent years, hollow fiber membrane contactors are regarded as an advanced technique with several competitive advantages over conventional technologies such as easy scale-up, independent control of flow rates, more operational flexibility, absence of flooding and foaming as well as high interfacial area per unit volume. However, many factors such as the membrane material selection, proper choice of solvent, and membrane module design are critical to success. In this regard, this paper aims at covering all areas related to hollow fiber membranes, including membrane material, membrane modification, membrane surface modification, shape, solvent characterization, operating parameters and costs, hybrid process, membrane lifetime, and energy consumption as well as commercially available systems. Current progress, future potential, and development of pilot-scale applications of this strategy are also assessed carefully. Furthermore, pore wetting as the main technical challenge in membrane contactor industrial implementation for post- and pre-combustion CO2 capture processes is investigated in detail.

Effect of ionic liquid on formation of copolyimide ultrafiltration membranes with improved rejection of La3+

Ultrafiltration (UF) as a widely used industrial separation method with optimal selection of membrane materials can be applied to extract rare earth metals from dilute solutions formed during the processing of electronic waste by hydrometallurgical methods. In the present work, promising UF copolyimide membranes were prepared using [hmim][TCB] ionic liquid (IL) co-solvent which can be considered as an environmentally friendly alternative to conventional solvents. The membranes were characterized by ATR-FTIR, TGA, SEM and quantum chemical calculations. A significant difference in morphology of these membranes was revealed by SEM of membrane cross-sections; the P84 membrane has finger-like structure of porous substrate in contrast to spongy structure of substrate for the P84/IL membrane due to a higher dynamic viscosity of the casting solution. The transport parameters were determined in ultrafiltration tests with pure water and an aqueous solution of bovine serum albumin. The addition of ionic liquid to the P84 casting solution increases the performance of the membrane. The rejection capacity was evaluated with respect to La3+ in the form of a lanthanum alizarin complex (LAC) in aqueous acetone solution. The P84 membrane prepared using IL showed a high rejection (98.5%) with respect to LAC, as well as a significant productivity.

Utilization of drinking water bottle waste as a sustainable and low-cost membrane material in water purification

The rapid development of membrane technology in various applications requires new membrane materials to achieve good separation performance. Materials in great demand are low in cost, easy to prepare, sustainable, and have good separation performance. In addition, consideration of environmental aspects is also crucial in the selection of membrane materials. On the other hand, plastic bottle waste, which increases every year (381.73 million tons), has the property of forming films or thin layers. Therefore, plastic bottle waste as a low-cost, sustainable, and “green” membrane material has great potential. The membrane from PET plastic bottle waste (PET-B membrane) was prepared using the immersion-precipitation phase inversion technique. Modification of the membrane is done by adding LiCl as an additive. Furthermore, the fabricated membranes were tested for their performance in water purification. The results showed that the PET-B membrane had a porosity of 74.8%. The addition of LiCl can increase the porosity of the PET-B membrane to 81.4%. The addition of LiCl caused an increase in flux to 3 times (65.30 Lm-2h-1bar−1 to 171.1 Lm-2h-1bar−1) and an increase in rejection from 64.46% to 99.45%.

Synchronous Design of Membrane Material and Process for Pre-Combustion Co2 Capture: A Superstructure Method Integrated Membrane Material Selection

Synchronous Design of Membrane Material and Process for Pre-Combustion Co2 Capture: A Superstructure Method Integrated Membrane Material Selection

Influence of different material parameters on nonlinear vibration of the cylindrical skeleton supported prestressed fabric composite membrane

Abstract In order to study the influence of geometric nonlinearity and material parameters on the free vibration behavior of the cylindrical skeleton supported prestressed fabric composite membrane. In this paper, based on von Karman's large deflection theory and D’Alembert's principle, the governing equations of nonlinear viscous damped prestressed free vibration of frame supported anisotropic membrane structures were established. By using Galerkin and KBM perturbation method, the analytical expressions of frequency function, displacement function and mode shape of nonlinear free vibration were obtained. In order to verify the effectiveness and effective range of the method, the fourth order Runge-Kutta method was used for numerical calculation. The calculation examples of membrane material parameters were given. The calculation and analysis of different membrane prestress, different length width ratio, different rise span ratio and different material parameters (elastic modulus ratio, viscous damping and material density) were carried out. The results were compared with the numerical results obtained by Runge-Kutta method to verify the accuracy of the method. The research results of this paper provide a theoretical reference for the selection of membrane materials, the subsequent calculation of wind-induced stability of steel skeleton membrane structure and the design of wind-driven rain resistance.

Revolutionizing Membrane Design Using Machine Learning-Bayesian Optimization.

Polymeric membrane design is a multidimensional process involving selection of membrane materials and optimization of fabrication conditions from an infinite candidate space. It is impossible to explore the entire space by trial-and-error experimentation. Here, we present a membrane design strategy utilizing machine learning-based Bayesian optimization to precisely identify the optimal combinations of unexplored monomers and their fabrication conditions from an infinite space. We developed ML models to accurately predict water permeability and salt rejection from membrane monomer types (represented by the Morgan fingerprint) and fabrication conditions. We applied Bayesian optimization on the built ML model to inversely identify sets of monomer/fabrication condition combinations with the potential to break the upper bound for water/salt selectivity and permeability. We fabricated eight membranes under the identified combinations and found that they exceeded the present upper bound. Our findings demonstrate that ML-based Bayesian optimization represents a paradigm shift for next-generation separation membrane design.

Green hydrogen enrichment with carbon membrane processes: Techno-economic feasibility and sensitivity analysis

• Screening suitable membrane materials for fermentative biohydrogen enrichment. • Optimization of the process operating parameters for hydrogen enrichment at a recovery of 90%. • A two-stage carbon membrane system was found to be techno-economically feasible for biohydrogen purification. • A lower specific cost of $0.06/N m 3 was estimated to achieve the biohydrogen purity of 99.5 vol% compared to PSA. Biohydrogen production from biomass through dark fermentation provides a great potential to achieve a green hydrogen economy for sustainable energy development. However, the purification of fermentative biohydrogen usually contains 30–40 vol% CO 2 at small-scale plants requires advanced separation technologies. Carbon molecular sieving membranes are considered as an alternative solution in this application. This work focuses on the techno-economic feasibility analysis of H 2 -selective carbon membrane systems for biohydrogen enrichment by investigation of process design, optimization of operating parameters, and the selection of membrane materials. High vacuum operation on the permeate is favorable to reduce the specific cost as the membrane-related capital cost is dominating the total cost. While the operation with feed gas compression provides better separation performance, and the minimum specific cost of $ 0.026/Nm 3 at 6 bar was identified to achieve the hydrogen recovery of 90%. A two-stage carbon membrane system is technically feasible to reach the biohydrogen purity of >99.5 vol% with the specific cost of $ 0.06/Nm 3 , which is lower than pressure swing adsorption. The sensitivity analysis indicates that the carbon membrane system is scalable and flexible in responding to the variation of plant capacity with the feed flow ranges from 500 to 2500 Nm 3 /h without significant changes in production cost. Compared to the enhancement of membrane selectivity, improving hydrogen permeance by developing submicrometer asymmetric carbon membranes is urgently needed to increase its competitiveness for biohydrogen purification.

Highly permeable and antioxidative graphene oxide membranes for concentration of hydrogen peroxide aqueous solution

Hydrogen peroxide, as a green oxidant, received broad and increasing applications. Membrane technology affords a promising solution to achieve in-situ production and concentration of hydrogen peroxide. Membrane material selection and structure design remain a grand challenge arising from the strong oxidation property of hydrogen peroxide. Herein, we explored graphene oxide membranes to concentrate hydrogen peroxide for the first time. By manipulating the cross-linking process of thiourea molecules, the interlayer channel size can be tuned in the range of 2.9–3.2 Å, ensuring the distinct molecular sieving between water and hydrogen peroxide. The graphene oxide membranes displayed superior separation performance with separation factor of 22.8 and permeation flux of 18.2 kg m−2 h−1. Compared with conventionally water-permeable membranes, graphene oxide membranes exhibit excellent antioxidative ability and stability in the 168 h operation test.

Efficiency of removal of whey protein from sweet whey using polymeric microfiltration membranes

Our objective was to measure whey protein removal percentage from separated sweet whey using spiral-wound (SW) polymeric microfiltration (MF) membranes using a 3-stage, 3× process at 50°C and to compare the performance of polymeric membranes with ceramic membranes. Pasteurized, separated Cheddar cheese whey (1,080 kg) was microfiltered using a polymeric 0.3-μm polyvinylidene (PVDF) fluoride SW membrane and a 3×, 3-stage MF process. Cheese making and whey processing were replicated 3 times. There was no detectable level of lactoferrin and no intact α- or β-casein detected in the MF permeate from the 0.3-μm SW PVDF membranes used in this study. We found BSA and IgG in both the retentate and permeate. The β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) partitioned between retentate and permeate, but β-LG passage through the membrane was retarded more than α-LA because the ratio of β-LG to α-LA was higher in the MF retentate than either in the sweet whey feed or the MF permeate. About 69% of the crude protein present in the pasteurized separated sweet whey was removed using a 3×, 3-stage, 0.3-μm SW PVDF MF process at 50°C compared with 0.1-μm ceramic graded permeability MF that removed about 85% of crude protein from sweet whey. The polymeric SW membranes used in this study achieve approximately 20%lower yield of whey protein isolate (WPI) and a 50% higher yield of whey protein phospholipid concentrate (WPPC) under the same MF processing conditions as ceramic MF membranes used in the comparison study. Total gross revenue from the sale of WPI plus WPPC produced with polymeric versus ceramic membranes is influenced by both the absolute market price for each product and the ratio of market price of these 2 products. The combination of the market price of WPPC versus WPI and the influence of difference in yield of WPPC and WPI produced with polymeric versus ceramic membranes yielded a price ratio of WPPC versus WPI of 0.556 as the cross over point that determined which membrane type achieves higher total gross revenue return from production of these 2 products from separated sweet whey. A complete economic engineering study comparison of the WPI and WPPC manufacturing costs for polymeric versus ceramic MF membranes is needed to determine the effect of membrane material selection on long-term processing costs, which will affect net revenue and profit when the same quantity of sweet whey is processed under various market price conditions.

Capacitive micromachined ultrasonic transducers: Transmission evaluation with different membrane materials and dimensions

Abstract Capacitive micromachined ultrasonic transducers (CMUTs) are dominant in generating and receiving acoustic signals. CMUT transmission efficiency solely depends upon the membrane material utilized. This work presents the structural examination of receiving and transmitting characteristics of CMUT with divergent membrane materials, namely Silicon (Si), Silicon Nitride ( Si 3 N 4 {\mathrm{Si}_{3}}{\text{N}_{4}} ), Indium Phosphide (InP), Zinc Oxide (ZnO), and Polysilicon (Poly-Si). The analysis includes the membrane deflection, pull-in voltage, output pressure, resonant frequency and capacitance modification with variable DC voltage. It has been found that InP gives the pull-in voltage comparable to Si in the receiving mode and have more transduction efficiency in transmitting mode. Effect of dimensions of CMUT on pull-in voltage and resonant frequency are also discussed. The major contribution lies in the analytical and estimation study of CMUT for appropriate membrane material selection meant for transmission and reception in the field of pressure sensing application.

Microwave synthesis of NaA zeolite membranes on coarse macroporous α-Al2O3 tubes for desalination

Abstract Membrane-based desalination technology is progressing continuously to meet world fresh water supply. However, selection of suitable membrane materials for this technology is still a challenge. Zeolite membranes are one of the promising candidates for molecular separations, but due to low water flux their applications in desalination technology are very limited. In this work, NaA zeolite membranes on coarse macroporous α-Al2O3 tubes synthesized by microwave-assisted heating method were explored for desalination by pervaporation aiming at improving the water flux. Under the optimized synthesis conditions, the fabricated membrane showed the highest water flux of 9.58 kg/(m2·h) with ion rejection (>99.9%) for the separation of 3.5 wt % (0.6 mol/L) NaCl aqueous solution at 348 K. The effect of operating temperature, feed concentration, and different saline solutions on the desalination performance of the membranes were also investigated in detail. The synthesized NaA zeolite membrane delivered excellent separation performance with stable water flux of 8.24 kg/(m2·h), and total ion rejection (>99.9%) within the investigated period of 72 h for simulated seawater desalination, demonstrating the NaA zeolite membranes would be potential candidates for desalination.

Temperature distribution on dielectric membrane structures for sensitive elements of semiconductor gas sensors

The aim of this article is to show a simulation of temperature distribution on dielectric membrane structures with membranes of different dielectric materials in the measuring mode of a semiconductor gas sensor. The simulation results were obtained using the software package Synopsys TCAD. In various moments of the measuring cycle were obtained two-dimensional temperature distributions on membrane structures. Dependencies of temperature versus time for the variety of the coordinates on membranes, temperature versus coordinates at the sensitive layer area’s highest heat value and temperature versus time in the center of the membranes are presented. Recommendations are given for the selection of membrane material for the heat-insulating membrane structure of sensitive elements for semiconductor gas sensors.