Application Of Polymeric Membranes Research Articles

Polyvinyl alcohol membrane incorporated with amine-modified silica nanoparticles and ionic liquid for facilitated transport of CO2

The application of polymeric membranes in post-combustion carbon capture is limited by solution-diffusion. In this work, polyvinyl alcohol (PVA) membranes with facilitated transport of carbon dioxide (CO2) were improved by incorporating the fixed carrier, amine-modified silica nanoparticles (SiO2) and the mobile carrier [bmim][Tf2N] ionic liquid. The BET surface area of diethanolamine (DEA)-modified SiO2 nanoparticles decreased from 150.14 m2/g to 22.68 m2/g, but they improved the surface hydrophilicity of PVA membranes more significantly than the unmodified SiO2 nanoparticles due to the existence of secondary amine groups. Fourier transform infrared spectra confirmed the incorporation of secondary amine and anion of IL that can facilitate CO2 permeation. The thermogravimetric analysis also revealed that the thermal stability of PVA membranes was improved by incorporating inorganic nanoparticles and ionic liquid. The thickness of the dense PVA layer coated on polyethersulfone support increased by incorporating SiO2 and DEA-modified SiO2 nanoparticles, as shown by scanning electron microscope images. The positive effects of SiO2 nanoparticles on the CO2 separation performance of PVA membranes were enhanced by reducing the particle size and increasing particle loading. DEA elevated the enhancement through the Zwitterion mechanism. [bmim][Tf2N] IL also improved the CO2 separation performance of PVA membranes. Hence, the PVA membrane containing 2 wt% of DEA-modified SiO2 nanoparticles (15-20 nm) and 0.4 M of [bmim][Tf2N] IL in ethanol attained a CO2 permeance of 3016 GPU and CO2/N2 selectivity of 62.08.

Applications of Polymeric Membranes with Carbon Nanotubes: A Review.

Nanomaterials have been commonly employed to enhance the performance of polymeric membrane materials that are used in several industrial applications. Carbon nanotubes (CNTs) have gained notable attention over the years for use in membrane technology due to their anti-biofouling properties, salt rejection capability, exceptional electrical conductivity, and mechanical properties. This paper aims to discuss some of the recent applications of CNTs in membrane technology and their effect on a larger scale. The paper reviews successful case studies of incorporation of CNTs in membranes and their impact on water purification, desalination, gas separations, and energy storage, in an effort to provide a better understanding of their capabilities. Regarding the future trends of this technology, this review emphasizes improving the large-scale production processes and addressing environmental and health-related hazards of CNTs during production and usage.

Application of polymeric membranes and membrane processes in energy, environment, and medicine

Application of polymeric membranes and membrane processes in energy, environment, and medicine

Polymeric membranes for biomedical applications

AbstractThe rapid development of nanotechnology paved the way for further expansion of polymer chemistry and the fabrication of advanced polymeric membranes. Such modifications allowed enhancing or adding some unique properties, including mechanical strength, excellent biocompatibility, easily controlled degradability, and biological activity. This chapter discusses various applications of polymeric membranes in three significant areas of biomedicine, including tissue engineering, drug delivery systems, and diagnostics. It is intended to highlight here possible ways of improvement the properties of polymeric membranes, by modifying with other polymers, functional groups, compounds, drugs, bioactive components, and nanomaterials.

Catalytic Ozonation and Membrane Contactors—A Review Concerning Fouling Occurrence and Pollutant Removal

Membrane filtration has been widely used in water and wastewater treatment. However, this process is not very effective for the removal of refractory organic compounds (e.g., of pharmaceutical origin). Coupling membrane filtration with ozonation (or other Advanced Oxidation Methods) can enhance the degradation of these compounds and, subsequently, the incidence of membrane fouling (i.e., the major problem of membrane uses) would be also limited. Ozonation is an efficient oxidative process, although ozone is considered to be a rather selective oxidant agent and sometimes it presents quite low mineralization rates. An improvement of this advanced oxidation process is catalytic ozonation, which can decrease the by-product formation via the acceleration of hydroxyl radicals production. The hydroxyl radicals are unselective oxidative species, presenting high reaction constants with organic compounds. An efficient way to couple membrane filtration with catalytic ozonation is the deposition of an appropriate solid catalyst onto the membrane surface. However, it must be noted that only metal oxides have been used as catalysts in this process, while the membrane material can be of either polymeric or ceramic origin. The relevant studies regarding the application of polymeric membranes are rather scarce, because only a few polymeric materials can be ozone-resistant and the deposition of metal oxides on their surface presents several difficulties (e.g., affinity etc.). The respective literature about catalytic membrane ozonation is quite limited; however, some studies have been performed concerning membrane fouling and the degradation of micropollutants, which will be presented in this review. From the relevant results it seems that this hybrid process can be an efficient technology both for the reduction of fouling occurrence as well as of enhancement of micropollutant removal, when compared to the application of single filtration or ozonation.

Facile preparation of persistently hydrophilic poly(vinylidene fluoride-co-trifluorochloroethylene) membrane based on in-situ substitution reaction

The predominant method to mitigate membrane fouling is based on hydrophilic modification such as additive blending and surface treatment. But the disadvantages such as prone to leaching from membrane, high cost of amphiphilic copolymer, may cause membrane damage and may decrease water flux are stumbling blocks to the further development and application of polymer membranes. Poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) is attracting ncreasing attention due to its good chemical resistance, excellent alkali resistance, high thermal stability and membrane forming properties. Herein, a novel and simple one-step strategy to prepare persistently hydrophilic PVDF-CTFE membrane based on in-situ substitution reaction is reported. In this method, hydrophilic polyhydroxy meglumine is immobilized in PVDF-CTFE membrane via grafting reaction with the low bond energy C–Cl bond of PVDF-CTFE during casting solution preparation. The results show that meglumine is successfully immobilized in membrane surface and matrix, thus obviously improving the membrane hydrophilicity. Moreover, the water flux is increased (up to 185%) and the mechanical strength and pore size are maintained simultaneously. The optimum membrane exhibits excellent fouling resistance (almost 100% flux recovery ratio). The simple one-step method not only improves the hydrophilicity, but also avoids the obvious negative effect normally accompanied by conventional methods on the mechanical strength and permeability.

Application of polymer membranes in downstream processes

AbstractThe purpose of downstream processing in a fermentation technology is the isolation, purification and concentration of the final product. Membrane processes are generally used in these steps. In this paper, the application possibilities of polymer membranes in pressure-driven membrane techniques (microfiltration, ultrafiltration, nanofiltration), pervaporation, dialysis and electrodialysis are presented.

Sustainability considerations in membrane-based technologies for industrial effluents treatment

Treatment of industrial effluents (EFs) from the polluted wastewater sources using membrane technologies is an effective and attractive alternative to overcome the weaknesses of some of the conventional wastewater treatment processes, especially when dealing with EFs loaded with recalcitrant organic pollutants and toxic substances. The application of various polymeric and inorganic membrane based technologies to be used for the treatment of industrial EFs has attracted a considerable attention in the past decades. In this regard, a critical discussion on the sustainability of various aspects of membrane technologies would promote the commercialization of these technologies. In this review, various sustainability criteria in technical, economic, environmental, and social categories have been considered for a critical discussion on the current status and improvement opportunities of membrane technologies for the treatment of industrial EFs. While the application of polymeric membranes has been restricted by some bottlenecks to deal with some industrial effluents, metal oxides fabricated ceramic membranes, and especially those fabricated with nanostructured materials such as nano-zeolites, those made of metal organic frameworks as well as carbon-based fabricated membranes have shown a promising performance in the rejection of recalcitrant organic pollutants. In addition, the combinations of inorganic membrane technologies with other novel methods such as advanced oxidation processes (e.g., using engineered nanomaterials) can be considered among the best options to deal with such highly polluted effluents.

Impact of polymeric membrane breakage on drinking water quality and an online detection method of the breakage

ABSTRACTPolymeric membrane has been widely used for the treatment of drinking water in China, and the total treating capacity has reached up to 3.8 million m3/d. However, the membrane breakage found in the membrane modules in many water treatment plants resulted in an increase in turbidity and bacterial amount in the membrane permeate. In this study, a membrane module running for 3 years in a full-scale application was examined in terms of the breaking positions and the numbers of the broken fibers. It was found that most of the breaking positions were mainly on the outlet side of the module and that the distance from these points to the outlet was about 1/10–2/10 length of the membrane module. The lab-scale tests showed that the increase of the numbers of the breaking fibers in the membrane module (the breaking fibers were from 1 to 4 of 75 fibers) resulted in the increase in turbidity, particle count and the amount of total bacteria and coliform bacteria. Meanwhile, the water quality after the filtration with broken membrane fibers was similar to the quality of the raw water, which indicated that once the membrane fiber breakage occurred in the membrane module, the quality of drinking water after membrane filtration was significantly affected. Furthermore, the breaking position closer to the outlet side of the membrane module exposed much higher microbiological risk than those in the middle or near the bottom side. A pilot scale test was conducted by using a membrane module with 6600 fibers, and the effect of the membrane breakage (1–4 broken fibers) on water quality was also investigated. The results indicated that periodical backwashing caused drastic fluctuation of turbidity, particle count and the bacterial amount in the permeate water, which might be due to the washing force and self-blocking action inside the hollow fibers. Moreover, there is a good quantitative relationship (R2 = 0.945) between particle count and the bacterial amount, which indicated that an online detection of particle count can be used to evaluate the bacterial risk. It was also suggested that the online detection of particle count after backwashing within 100 s would be a quick and precise method to identify any fiber breakage in time. These results are very important for the safety issue in the application of polymeric membrane to water treatment plants.

Porous polymeric membranes with thermal and solvent resistance

Polymeric membranes are highly advantageous over their ceramic counterparts in terms of the simplicity of the manufacturing process, cost and scalability. Their main disadvantages are low stability at temperatures above 200°C, and in organic solvents. We report for the first time porous polymeric membranes manufactured from poly(oxindolebiphenylylene) (POXI), a polymer with thermal stability as high as 500°C in oxidative conditions. The membranes were prepared by solution casting and phase inversion by immersion in water. The asymmetric porous morphology was characterized by scanning electronic microscopy. The pristine membranes are stable in alcohols, acetone, acetonitrile and hexane, as well as in aqueous solutions with pH between 0 and 14. The membrane stability was extended for application in other organic solvents by crosslinking, using various dibromides, and the efficiency of the different crosslinkers was evaluated by thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). POXI crosslinked membranes are stable up to 329°C in oxidative conditions and showed organic solvent resistance in polar aprotic solvents with 99% rejection of Red Direct 80 in DMF at 70°C. With this development, the application of polymeric membranes could be extended to high temperature and harsh environments, fields currently dominated by ceramic membranes.

Molecularly Engineered Polymer-Based Systems in Drug Delivery and Regenerative Medicine.

Polymer-based systems are attractive in drug delivery and regenerative medicine due to the possibility of tailoring their properties and functions to a specific application. The present review provides several examples of molecularly engineered polymer systems, including stimuli responsive polymers and supramolecular polymers. The advent of controlled polymerization techniques has enabled the preparation of polymers with controlled molecular weight and well-defined architecture. By using these techniques coupled to orthogonal chemical modification reactions, polymers can be molecularly engineered to incorporate functional groups able to respond to small changes in the local environment or to a specific biological signal. This review highlights the properties and applications of stimuli-responsive systems and polymer therapeutics, such as polymer-drug conjugates, polymer-protein conjugates, polymersomes, and hyperbranched systems. The applications of polymeric membranes in regenerative medicine are also discussed. The examples presented in this review suggest that the combination of membranes with polymers that are molecularly engineered to respond to specific biological functions could be relevant in the field of regenerative medicine.

Polymeric Gas-Separation Membranes for Petroleum Refining

Polymeric gas-separation membranes were commercialized 30 years ago. The interest on these systems is increasing because of the simplicity of concept and low-energy consumption. In the refinery, gas separation is needed in many processes such as natural gas treatment, carbon dioxide capture, hydrogen purification, and hydrocarbons separations. In these processes, the membranes have proven to be a potential candidate to replace the current conventional methods of amine scrubbing, pressure swing adsorption, and cryogenic distillation. In this paper, applications of polymeric membranes in the refinery are discussed by reviewing current materials and commercialized units. Economical evaluation of these membranes in comparison to traditional processes is also indicated.

Preparing of Heatable, CNT-Functionalized Polymer Membranes for Application in Textile Composites

The electrically induced heating of textile composite materials is already applied in the clothing and outdoor use. However, making thin, flexible and washable heating layers remains a challenge. Based on various polymers thin electrically heatable polymer sheets were developed using multi-walled carbon nanotubes as electrically conductive fillers in silicone, polyurethane as well as polyvinylchloride. To prepare the membranes a knife coating process was applied. The viscosity of the polymer masses, the particle alignment, the percolation as well as the electrically and heating properties of the membranes were investigated.

Morphology Control of Polysulfone Membranes in Filtration Processes: a Critical Review

AbstractPolysulfone (PSU) membranes have been widely applied in microfiltration and ultrafiltration processes due to their excellent properties, such as chemical inertness across the entire pH range, compressive strength, and thermal stability. Despite these advantages, the application of PSU membranes in filtration processes has often been restricted due to their hydrophobic nature, which results in serious membrane fouling and a reduced permeate flux. Moreover, PSU membranes suffer from several disadvantages, including bulky structure, low binding force between fibers, and poor mechanical properties. The key factor in the development and application of polymeric membranes is the control of its polymeric morphology due to the significant influence of membrane morphology on the membrane performance. Effective techniques of controlling PSU membrane morphology are accessed, and the effects of the morphological control on mechanical properties, chemical stability, membrane performance, and membrane fouling are investigated. Findings from various individual studies were analyzed and discussed in order to provide a critical review of this subject. The results emphasized that the membrane pore size and surface porosity mostly governs PSU membrane morphology, which enhances membrane performance and reduces membrane fouling.

Application of Polymeric Membranes in Biohydrogen Purification and Storage

Artificial separation membranes, as selective mass transport barriers allow different gases to permeate at different rates. Many polymers exhibit great differences in the permeation rates and polymers, often in the form of non-porous films, constitute the group of the most important materials for gas separation membranes. Feasibility and efficiency of membrane technology – besides material selection – significantly depend on the separation circumstances such as feed composition, pressures and flows. All these aspects are discussed in this study. Polymeric membranes are very suitable for hydrogen recovery from biohydrogen. They can be employed under similar conditions of biohydrogen formation. Commercial membranes and apparatus can be utilized. Some biohydrogen components – such as nitrogen – can be removed easily, while others – e.g. carbon dioxide, moisture and hydrogen sulfide – likely require multi-stage or cascade processes to be separated. In the recent decade, a range of new polymers, new membrane materials, novel membrane processes were developed and have been proven in the laboratory scale. They brought higher separation efficiency with better economy. Process utilizing polymer foams with closed pores combine membrane based separation and hydrogen absorption capacity. Ionic liquid supported membranes utilize ionic liquids filled in the pores of polymer membranes and take advantage of ionic liquids separation abilities. Integrated solutions seem most feasible for biohydrogen purification and storage. Keywords: Biohydrogen, hydrogen, membrane, separation, storage.

Nanostructured bacterial cellulose-poly(4-styrene sulfonic acid) composite membranes with high storage modulus and protonic conductivity.

The present study reports the development of a new generation of bio-based nanocomposite proton exchange membranes based on bacterial cellulose (BC) and poly(4-styrene sulfonic acid) (PSSA), produced by in situ free radical polymerization of sodium 4-styrenesulfonate using poly(ethylene glycol) diacrylate (PEGDA) as cross-linker, followed by conversion of the ensuing polymer into the acidic form. The BC nanofibrilar network endows the composite membranes with excellent mechanical properties at least up to 140 °C, a temperature where either pure PSSA or Nafion are soft, as shown by dynamic mechanical analysis. The large concentration of sulfonic acid groups in PSSA is responsible for the high ionic exchange capacity of the composite membranes, reaching 2.25 mmol g(-1) for a composite with 83 wt % PSSA/PEGDA. The through-plane protonic conductivity of the best membrane is in excess of 0.1 S cm(-1) at 94 °C and 98% relative humidity (RH), decreasing to 0.042 S cm(-1) at 60% RH. These values are comparable or even higher than those of ionomers such as Nafion or polyelectrolytes such as PSSA. This combination of electric and viscoelastic properties with low cost underlines the potential of these nanocomposites as a bio-based alternative to other polymer membranes for application in fuel cells, redox flow batteries, or other devices requiring functional proton conducting elements, such as sensors and actuators.

Tissue Scaffold Engineering by Micro-Stamping

ABSTRACTA hand operated benchtop stamping press was developed to conduct research on microscale hole fabrication in polymer membranes for applications as scaffolds in tissue engineering. A biocompatible and biodegradable polymer, poly(ε-caprolactone), was selected for micropunching. Membranes between 30 μm and 50 μm thick were fabricated by hot melt extrusion, but could not be stamped with a 200 μm circular punch at room temperature, regardless of die clearance due to excessive strain to fracture. This problem was overcome by cooling the membrane and die sets with liquid nitrogen to take advantage of induced brittle behavior below the polymer’s glass transition temperature. While cooled, 203 μm hole patterns were successfully punched in 33 μm thick poly(ε-caprolactone) membranes with 11% die clearance, achieving 71% porosity.

Cu(L)](NO3)2 (L=4,7‐Bis(3‐aminopropyl)‐1‐thia‐4,7‐diazacyclononane) as a Suitable Ionophore for Construction of Thiocyanate‐Selective Electrodes and Their Use in Determination of Urinary and Salivary Thiocyanate Concentration

AbstractThe construction, performance characteristics, and application of polymeric membrane (PME) and coated graphite (CGE) thiocyanate‐selective electrodes are reported. The electrodes were prepared by incorporating the complex [Cu(L)](NO3)2 (L=4,7‐bis(3‐aminopropyl)‐1‐thia‐4,7‐diazacyclononane) into a plasiticized poly(vinyl chloride) membrane. The influence of membrane composition, pH of test solution, and foreign ions were investigated. The electrodes reveal Nernstian behavior over a wide SCN− ion concentration range (1.0×10−6–1.0×10−1 M for PME and 5.0×10−7–1.0×10−2 M for CGE) and show fast dynamic response times of 15 s and lower. The proposed sensors show high selectivity towards thiocyanate over several common organic and inorganic anions. They were successfully applied to the direct determination of thiocyanate in urine and saliva of smokers and nonsmokers, and as an indicator electrode in titration of Ag+ ions with thiocyanate.

Characterization of track etched membranes by gas permeation

The application of polymeric membrane in combination with the metallic films can be used for the gas purification; in particular, the hydrogen where the molecular size is very small. The affinity of hydrogen to certain metals assists the flow of hydrogen, however, restricts the permeation of other gases. However, the flow rate is very small in the dense membranes. Attempts have been made to etch the nuclear tracks of the polymeric membranes in a very controlled way to achieve the conical etched tracks to meet the vertex. This has been characterized by gas permeation measurements.

Characterization of nuclear tracks by positron annihilation and gas permeation

The application of polymeric membrane in combination with metallic films can be used for gas purification in particular for hydrogen where the molecular size is very small. The affinity of hydrogen to certain metals assists the flow of hydrogen, although it restricts the permeation of other gases. However, the flow rate is very small in dense membranes. Attempts have been made to generate nuclear tracks in polymeric membranes to control the gas flow. These tracks can be characterized by positron lifetime spectroscopy and gas permeation measurements. The long lifetime of ortho-positronium gives the estimate of size of the track-free volume of the order of 0.25 nm . The nuclear tracks can be modified by a chemical etching process. The chemical etching normally takes place from both sides of the membrane. When the etched pits from both sides meet, a rapid increase in gas permeation is observed. The size of the nano opening of the track has been observed for two different gases hydrogen and carbon dioxide, which have a molecular size of 0.2 and 0.4 nm , respectively.