Electrospun Filters Research Articles

Electrospun controlled release anti-quorum sensing filter for biofouling prevention in MCE membranes

The formation of biofilm on the surface of water filtration membranes results in decreased flux through the filter and output of contaminated water despite filtration. The reduction in clean water output due to biofilm diminishes filtration efficiencies and feasibility of filtration in regions where alternatives do not exist. In this work, we sought to lower biofouling concerns through examination of anti-quorum sensing (anti-QS) molecules in P. aeruginosa (PAO1). QS plays a critical initial role in biofilm formation. Therefore, we hypothesized that disruption of this communication mechanism at the filtration surface would result in lower biofilm growth and higher water outputs. An electrospun filter coating was developed to prevent biofilm formation on the surface of filtration membranes. The filter coating was deposited by electrospinning (ES) fibers that contained a polymer blend made up of one hydrophobic (polycaprolactone, PCL) and one hydrophilic (polyethylene glycol, PEG) polymer to provide controlled release of anti-quorum sensing molecules (Urolithin A) to prevent biofilm formation for an extended filtration test. Results showed that a 3:1 PCL to PEG polymer blend coating containing Urolithin A (200 µg/mL) provided significant physical disruption as well as molecular interruption of biofilm formation as compared to the pristine membrane (83.48 % reduction). While fibers exhibited smooth morphologies prior to nanofiltration tests, the fibers became porous after 4 hr tests in areas where PEG had dissolved and released Urolithin A. The controlled release of anti-QS molecules by electrospun fibers provided a significantly improved anti-biofilm methodology, improving biovolume reduction by 26.05 % and increasing flux by 52.78 % as compared to similar technologies reported. In addition to these findings, this work demonstrated Urolithin A disruption of PAO1 motility on agar (65.29 % reduction @ 100 µg/mL) and reduction in biofilm thickness (84.15 % reduction @ 200 µg/mL) by dissolution from electrospun fibers in liquid culture.

Potential use of biodegradable polymers for facemask filter inserts produced using electrospinning methods

AbstractThe elevated use of petroleum‐based polymers to manufacture single‐use disposable face masks is a serious environmental concern that has detrimental effects on the ecosystem. The research on using biodegradable facemasks is promising to reduce the environmental impacts of the single‐use non‐degradable facemask. A reusable cloth‐based facemask with effective filtration could benefit society. Many studies suggest polyvinyl alcohol (PVA), polybutylene adipate terephthalate (PBAT), and polylactic acid (PLA) as viable biopolymers for facemask filter layer fabrication. In this work, an electrospun filter layer inserts with PVA, PBAT, and PLA polymers were produced by depositing electrospun nanofibers on non‐woven cotton layers followed by conventional sealing. The fabricated filter inserts were used in cloth‐based facemasks and were tested for filtration efficiencies and breathability. PVA facemask insert showed the best performance with 66.7% filtration efficiency and breathability of 0.66 m bar, whereas the lowest filtration efficiency was found for PBAT electrospun filter medium. The relation between filter membrane morphology and facemask performance indicates that a smaller diameter and uniform morphology results in better filtration and breathability of the facemask filter inserts.Highlights Petroleum‐based facemasks harm ecosystems. Biodegradable facemasks reduce environmental impact. Electrospun nanofibers of polyvinyl alcohol (PVA), polybutylene adipate terephthalate, and polylactic acid on cotton. PVA insert showed 66.7% filtration and 0.66 m bar breathability. Smaller, uniform fibers enhance filtration and breathability.

Development of electrospun filter with high efficiency to reduce disturbance on gas detection in dusty environments

AbstractIn some harsh environments, certain gases are very important for the safety, such as methane gas from underground coal mines, which may explode causing catastrophic consequences. However, such gas detections are often disturbed by the particles. In this study, aiming at the scenario of underground coal mines, electrospun filters were developed and used as the pre‐filter of electronic nose (PFEN) to mitigate the disturbance on gas detection in dusty environments. Two poly (ε‐caprolactone) (PCL) filters and four poly (ε‐caprolactone)/graphene oxide (PCL/GO) filters have been prepared and compared with two commercial filters. The results shows that all filters did not affect the response of sensors to the detecting gas as compared with that without filters. The PCL/GO filter at GO concentration of 0.03% (PCL/GO‐3) had the best performance. The PCL/GO‐3 filter exhibited high removal efficiency of particulate matter (PM) with 99.27% (PM1), 99.67% (PM2.5), and 99.90% (PM10), low pressure drop of 75 Pa, and highest quality factor of 0.076 as compared with other filters. In addition, the PCL/GO‐3 filter exhibited higher tensile strength than those of other electrospun filters and commercial filters. These results indicate that the electrospun filters can be excellent option to be used as PFEN for mitigating PM deposition for gas detection in dusty environments.

Stabilized Electrospun Polyacrylonitrile Fibers for Advancements in Clean Air Technology

Particulate matter air pollution and volatile organic compounds released into the air from the incomplete combustion of fossil fuels and wildfires creates significant damage to human health and the environment. Advances in air filtration and purification technology are needed to mitigate aerosol hazards. This article details an effort to explore the potential benefits of new materials and methods for the production of nonwoven air filtration media through electrospinning and stabilizing polyacrylonitrile fibers. The investigated production methods include electrospinning fibrous matting onto a stainless steel wire mesh and stabilizing the nonwoven media in a chamber furnace. The media is then tested for air filtration penetration and airflow resistance, and the fiber size distribution is measured using scanning electron microscopy. The experimental results show that the electrospun media approaches the performance criteria for airflow resistance and particle capture efficiency of high-efficiency particulate air (HEPA) filter media. Furthermore, performance estimations for electrospun media of increased thickness and for a decreased filtration velocity show potential to exceed the HEPA media resistance and efficiency criteria. Thus, it is suggested that electrospun and stabilized nonwoven fibrous media are candidates as alternatives to traditionally manufactured HEPA media and may potentially benefit modern air filtration technology and reduce hazards associated with particulate matter. Additionally, the authors recommend future exploration into the carbonization and activation of electrospun filter media for the adsorption and mitigation of volatile organic compounds as a secondary benefit, while maintaining high efficiency and low airflow resistance in the removal of particulate matter from aerosol streams.

The anti SARS-CoV-2 activity of nanofibrous filter materials activated with metal clusters.

Nanofibrous filter materials were prepared by electrospinning a solution of 28wt% poly(vinylidene fluoride) in N,N-dimethylacetamide with and without the addition of 2wt% AgNO3, Cu(NO3)2·2.5H2O or ZnCl2. X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectroscopy, thermogravimetric analysis, contact angle measurement, nitrogen sorption, and mercury intrusion porosimetry methods were used for the characterization of physical structure as well as the chemical composition of the electrospun materials. Particle filtration efficiency and antiviral activity against the SARS-CoV-2 alpha variant were tested in order to estimate the suitability of the prepared electrospun filter materials for application as indoor air filtration systems with virucidal properties. All filter materials prepared with salts demonstrated very high particle filtration efficiency (≥98.0%). The best antiviral activity was demonstrated by a material containing Cu(NO3)2·2.5H2O in the spinning solution, which displayed the decrease in the number of infectious virions by three orders of magnitude after a contact time of 12h. Materials with the addition of AgNO3 and ZnCl2 decreased the number of infectious virions after the same contact time by only ∼8 and ∼11 times, respectively.

High-efficiency retention of ultrafine aerosols by electrospun nanofibers

The versatility of nanofibrous polymeric materials makes them attractive for developing respiratory protective equipment. Ultrafine nanofibers effectively trap the most penetrating aerosols and exhibit consistent performance compared to conventional electret filters. Advanced nanofiber manufacturing technologies such as electrospinning can functionalize filter materials, enhancing them with unique antibacterial, catalytic, sensory, and other properties. Much of the current research in nanofibrous air filtration focuses on using nanofibers for lightweight personal protective equipment such as N95 respirators, but their use for higher levels of respiratory protection required for chemical, biological, radiological, and nuclear (CBRN) protection has not yet been comprehensively explored. In this study, we tested the hypothesis that electrospun filters could provide the particle filtration efficiency and breathing resistance required by the National Institute for Occupational Safety and Health Standard for CBRN air-purifying respirators. Our manufactured nanofibrous filters demonstrated submicron aerosol retention efficiency of > 99.999999%, which is four orders of magnitude better than the requirements of the CBRN standard. They also had a breathing resistance of ~ 26 mmH2O, which is more than twofold lower than the maximum allowable limit. Although the filter material from the gas mask cartridge currently in service with the U.S. military demonstrated a higher quality factor than electrospun filters, the comparative analysis of filter morphology suggested ways of improving nanofibrous filter performance by tuning nanofiber diameter distribution.

Polycaprolactone nanofiber membrane modified with halloysite and ZnO for anti-bacterial and air filtration

Use of breath protective equipment (e.g., air-filtering masks) is essential to protect personal health from the serious threat of air contamination and bacterial infection. As core filter layer materials of face masks, the nanofiber can be imparted with multifunctionality by nanoparticles modification, such as particulate matter (PM) filtration, bacterial inhibition and so on. Herein, the electrospun filter membranes were developed through incorporating the halloysite nanotubes (HNTs) and zinc oxide nanoparticles with the polycaprolactone (PCL) nanofibers. The composite HNTs-ZnO/PCL nanofibers exhibit high antibacterial efficiency of Staphylococcus aureus (S. aureus, 97.9%) and Escherichia coli (E. coli, 95.9%) bacterial strains. The PM particles filtration performance of HNTs-ZnO/PCL membrane can be obviously improved with an enhanced mechanical strength. Thus, the HNTs-ZnO/PCL nanofiber membranes might be a competitive filtering material for antibacterial protective mask filter layer, and the successful fabrication of the HNTs-ZnO/PCL face masks furtherly indicates the great potential in practical application.

Digital Twin Geometry for Fibrous Air Filtration Media

Computational modeling of air filtration is possible by replicating nonwoven nanofibrous meltblown or electrospun filter media with digital representative geometry. This article presents a methodology to create and modify randomly generated fiber geometry intended as a digital twin replica of fibrous filtration media. Digital twin replicas of meltblown and electrospun filter media are created using Python scripting and Ansys SpaceClaim. The effect of fiber stiffness, represented by a fiber relaxation slope, is analyzed in relation to resulting filter solid volume fraction and thickness. Contemporary air filtration media may also be effectively modeled analytically and tested experimentally in order to yield valuable information on critical characteristics, such as overall resistance to airflow and particle capture efficiency. An application of the Single Fiber Efficiency model is incorporated in this work to illustrate the estimation of performance for the generated media with an analytical model. The resulting digital twin fibrous geometry compares well with SEM imagery of fibrous filter materials. This article concludes by suggesting adaptation of the methodology to replicate digital twins of other nonwoven fiber mesh applications for computational modeling, such as fiber reinforced additive manufacturing and composite materials.

Filtration Performance of Ultrathin Electrospun Cellulose Acetate Filters Doped with TiO2 and Activated Charcoal

Air filters are crucial components of a building ventilation system that contribute to improving indoor air quality, but they are typically associated with relatively high pressure drops. The purpose of the study is to evaluate the effect of additives on ultrathin electrospun filters, the pressure drop, and the particle removal efficiency of uniformly charged particles. The fibres were electrospun under optimised conditions that resulted in a fast-fabricating process due to the properties of the cellulose acetate solution. Different ultrathin electrospun fibre filters based on cellulose acetate (CA) were fabricated: a pure CA electrospun fibre filter, two filters based on CA fibres separately doped with activated charcoal (AC) and titanium dioxide (TiO2), respectively, and a composite filter where the two additives, AC and TiO2, were embedded between two CA fibres layers. The ultrathin filters exhibited a low pressure drop of between 63.0 and 63.8 Pa at a face velocity of 0.8 m s−1. The filtration performance of uniformly charged particles showed a removal efficiency above 70% for particle sizes between 0.3 and 0.5 μm for all filters, rising above 90% for larger particles between 1 and 10 μm, which translates to the average sizes of pollens and other allergenic contaminant particles. Due to the positive impact on the fibre morphology caused by the additives, the composite filter showed the highest filtration performance among the produced filters, reaching 82.3% removal efficiency towards smaller particles and a removal of up to 100% for particle sizes between 5 and 10 μm. Furthermore, cellulose acetate itself is not a source of microparticles and is fully biodegradable compared to other polymers commonly used for filters. These ultrathin electrospun filters are expected to be practical in applications for better building environments.

Optimizing the Packing Density and Chemistry of Cellulose Nanofilters for High-Efficiency Particulate Removal

The global spread of COVID-19 as well as the worsening air pollution throughout the world have brought tremendous attention to the development of materials that can efficiently capture particulate matter. We suggest that the high porosity of electrospun filters composed of nanofibers could provide minimal obstruction to air flow, while their high tortuosity and surface area-to-volume ratio present an excellent platform to capture particulates. In this study, the removal of nanoscale particles via in-house fabricated cellulose nanofilters is significantly enhanced by chemically functionalizing the fibers’ surface via the deposition of the bioinspired glue polydopamine (PDA) or the polycation poly(diallyldimethylammonium chloride) (PDADMAC). The effects of filter packing density, layering thickness, and chemistry on their performance, i.e., their filtration efficiency, most penetrating particle size (MPPS), particle fractional penetration percent, and performance in a high relative humidity environment, were investigated. When evaluated in an extremely hazardous environment (PM concentration ∼ 2000 μg m–3), the filtration efficiency, pressure drop, and quality factor for the cellulose nanofilters were measured to be >98.0%, <200 Pa, and ∼0.03 Pa–1, respectively. When we evaluated the performance of a composite hydrophobic/hydrophilic filter in an 80% relative humidity environment, a 99.8% filtration efficiency was achieved. We have demonstrated that the removal of nanoscale particulates can be effectively captured using cellulose-based nanofilters, even in a nonideal high humidity environment. These fundamental investigations into the structure–property-chemistry relationships of in-house electrospun nanofilters on nanoscale particulate removal hold the potential to help drive the future engineering of nanofilters for air purification applications, which is a timely and extremely important concern.

Electrospun Fibers of Polybutylene Succinate/Graphene Oxide Composite for Syringe-Push Protein Absorption Membrane

The adsorption of proteins on membranes has been used for simple, low-cost, and minimal sample handling of large volume, low protein abundance liquid samples. Syringe-push membrane absorption (SPMA) is an innovative way to process bio-fluid samples by combining a medical syringe and protein-absorbable membrane, which makes SPMA a simple, rapid protein and proteomic analysis method. However, the membrane used for SPMA is only limited to commercially available protein-absorbable membrane options. To raise the method’s efficiency, higher protein binding capacity with a lower back pressure membrane is needed. In this research, we fabricated electrospun polybutylene succinate (PBS) membrane and compared it to electrospun polyvinylidene fluoride (PVDF). Rolling electrospinning (RE) and non-rolling electrospinning (NRE) were employed to synthesize polymer fibers, resulting in the different characteristics of mechanical and morphological properties. Adding graphene oxide (GO) composite does not affect their mechanical properties; however, electrospun PBS membrane can be applied as a filter membrane and has a higher pore area than electrospun PVDF membrane. Albumin solution filtration was performed using all the electrospun filter membranes by the SPMA technique to measure the protein capture efficiency and staining of the protein on the membranes, and these membranes were compared to the commercial filter membranes—PVDF, nitrocellulose, and Whatman no. 1. A combination of rolling electrospinning with graphene oxide composite and PBS resulted in two times more captured protein when compared to commercial membrane filtration and more than sixfold protein binding than non-composite polymer. The protein staining results further confirmed the enhancement of the protein binding property, showing more intense stained color in compositing polymer with GO.

A Sustainable Recycling Alternative: Electrospun PET-Membranes for Air Nanofiltration.

Currently, the inappropriate disposal of plastic materials, such as polyethylene terephthalate (PET) wastes, is a major environmental problem since it can cause serious damage to the environment and contribute to the proliferation of pathogenic microorganisms. To reduce this accumulation, PET-type bottles have been recycled, and also explored in other applications such as the development of membranes. Thus, this research aims to develop electrospun microfiber membranes from PET wastes and evaluate their use as an air filter media. The solution concentrations varied from 20 to 12% wt% of PET wastes, which caused a reduction of the average fiber diameter by 60% (from 3.25 µm to 1.27 µm). The electrospun filter membranes showed high mechanical resistance (4 MPa), adequate permeability (4.4 × 10−8 m2), high porosity (96%), and provided a high collection efficiency (about 100%) and low-pressure drop (212 Pa, whose face velocity was 4.8 cm/s) for the removal of viable aerosol nanoparticles. It can include bacteria, fungi, and also viruses, mainly SARS-CoV-2 (about 100 nm). Therefore, the developed electrospun membranes can be applied as indoor air filters, where extremely clean air is needed (e.g., hospitals, clean zones of pharmaceutical and food industry, aircraft, among others).

An explicit correlation between surface functionality, wettability, and leukocyte removal by electrospun filter media

The major motive of this investigation was to derive a correlation between surface functionality, wettability, and leukodepletion efficiency of electrospun filter media. Towards this, different extents of hydrophilicity and various functionalities were introduced to the electrospun poly (ethylene-co-vinyl alcohol) (EVAL) filter media via photografting of 2-hydroxyethyl acrylate (HEA) branches, photografting of N-(3-sulfopropyl)-N-methacroyloxyethyl-N,N- dimethylammonium betaine (SMDB) branches, and integration of glycine. All the filter media were designed to asymmetric filters with fiber sizes varying from 1.7 ± 0.2 μm to 2.4 ± 0.2 μm, pore sizes from 7.8 ± 1.5 μm to 23.3 ± 5.0 μm, water contact angles from 69 ± 10° to 134 ± 3 critical wetting surface tension (CWST) from 61.8 mN/m to > 88 mN/m and their performance was ascertained by carrying out whole blood filtration studies. It was observed that hydrophilic filter media resulted in a decreased adhesion of white blood cells (WBCs) than the unmodified EVAL filter media due the formation of a hydration layer. However, the hydrophilic SMDB grafted EVAL (PSMBD-g- EVAL) showed a high WBC adhesion than expected because of the net negative polarity of the PSMDB branches by which they could grasp the WBC even in presence of hydration layer. The efficacy of WBC adhesion by hydrophobic glycinated EVAL (EVAL-GLY) filter media was nearly as that of unmodified EVAL while the red blood cell (RBC) recovery was less pronounced (67 % lower than unmodified EVAL) due to the pore occlusion. However, there was no significant change in platelet adhesion for all filter media except PHEA-g-EVAL. Hemolysis induced by all the modified filter media was notably lesser than that of unmodified EVAL and was nearly zero. Thus, it is concluded that WBC and platelet adhesion are interdependent under dynamic conditions and it is difficult to achieve a selective adhesion of one in presence of the other.

Design and fabrication of nano-engineered electrospun filter media with cellulose nanocrystal for toluene adsorption from indoor air

The cellulose nanocrystal (CNC)-polyamide 6 (PA-6) composite nanofiber filters were fabricated and examined their structural and mechanical properties and toluene adsorption performances. The effect of polymer concentration (13 wt% and 17 wt%) and CNC ratio (0, 1.0 wt%, 1.5 wt%, and 2.0 wt%) on the characteristics and adsorption abilities of nanofiber filters were investigated. The nanofiber filter including 17 wt% PA-6 and 1.5 wt% CNC has shown the best toluene adsorption efficiency of 50% and improved mechanical properties. As a result, the nanofiber filter having CNC are effective, accessible and cost-saving materials and has been a good candidate as the toluene vapor capture media and it has nearly same removal efficiency like the conventional adsorbents with powder or particle forms. The resultant filters had excellent three-dimensional (3D) fiber structure having micro/nanopores and they can be used in potential applications such as catalyst supports, indoor air filter and respiration masks.

Ultrafine, self-crimp, and electret nano-wool for low-resistance and high-efficiency protective filter media against PM0.3

Frequent outbreaks of emerging infectious diseases (EIDs) make personal protective filter media in high demand. Electrospun nanofibrous materials are proved to be very effective in resisting virus-containing fine particles owing to their small fiber diameters; however, hindered by the intrinsic close-packing character of fine fibers, electrospun filters suffer from a relatively high air resistance, thereby poor breathing comfort. Here, we report a biomimetic and one-step strategy to create ultrafine and curly wool-like nanofibers, named nano-wool, which exhibit fluffy assembly architecture and powerful electret effect. By achieving the online self-crimp and in-situ charging of nanofibers, the curly electret nano-wool shows a small diameter of ~0.6 μm (two orders of magnitude lower than natural wool: ~20 μm) and an ultrahigh porosity of 98.7% simultaneously, together with an ultrahigh surface potential of 13260 V (one order of magnitude higher than previous filters). The structural advantages and powerful electret effect enable nano-wool to show excellent filtration efficacy (>99.995% for PM0.3) and low air resistance (55 Pa). Additionally, nano-wool can be easily scaled up, not only holding great industrial prospect in personal protective respirators, but also paving the way for developing next-generation wool in a cost-efficient and multifunctional form.

Composites Based on Nanoparticle and Pan Electrospun Nanofiber Membranes for Air Filtration and Bacterial Removal.

Often, solid matter is separated from particle-laden flow streams using electrospun filters due to their high specific surface area, good ability to capture aerial particulate matter, and low material costs. Moreover, electrospinning allows incorporating nanoparticles to improve the filter’s air filtration efficiency and bacterial removal. Therefore, a new, improved polyacrylonitrile (PAN) nanofibers membrane that could be used to remove air pollutants and also with antibacterial activity was developed. We engineered three different filters that are characterized by the different particles embedded in the PAN nanofibers: titanium dioxide (TiO2), zinc oxide (ZnO), and silver (Ag). Then, their filtration performance was assessed by quantifying the filtration of sodium chloride (NaCl) aerosol particles of 9 to 300 nm in diameter using a scanning mobility particle sizer. The TiO2_F filter displayed the smallest fiber diameter and the highest filtration efficiency (≈100%). Conversely, the Ag_F filter showed the highest quality factor (≈0.06 Pa−1) because of the lower air pressure drop. The resulting Ag_F nanofibers displayed a very good antibacterial activity using an Escherichia coli suspension (108 CFU/mL). Moreover, the quality factor of these membranes was higher than that of the commercially available nanofiber membrane for air filtration.

Fabrication of bead-on-string polyacrylonitrile nanofibrous air filters with superior filtration efficiency and ultralow pressure drop

The presence of ultrafine particle matter (PM) in air is one of the most hazardous environmental issues because of their severe threat to human health. Design and development of cost-effective and energy-efficient air filters to remove the PM by facile methods are highly demanded. Electrospun nanofibrous membranes have been explored for PM filtrations as they can achieve high removal efficiencies due to their ultrafine nanofibers. However, their enhanced particle removal efficiencies are at the cost of high pressure drops. In this work, porous bead-on-string filters with nanobeads along the nanofiber axis have been successfully fabricated by optimizing the polyacrylonitrile (PAN) concentration of electrospun dopes and ambient humidity condition during the electrospinning process. The combined effects of polymer concentration and humidity condition could achieve an unbalanced status between the repulsive and constrictive forces along the jets from the spinneret in the electrospinning process, which generated a filter with a desirable bead-on-string morphology. The nanobeads are able to reduce the packing density and alleviate the pressure drop through the filter while the ultrafine nanofibers guarantee the PM removal efficiency. Besides, the effects of nanofiber diameter, airflow rate and nanobead density on the filtration efficiency and pressure drop of NaCl solid and Paraffin oil aerosols with an average diameter of 300 nm have been investigated systematically. With the assistance of bead-on-string construction, the pristine PAN filter can easily achieve an excellent efficiency above 99% with a low pressure drop of 27 Pa at an airflow rate of 4.2 cm/s. This work suggests that transformation of electrospun filters from a nanofibrous structure to a bead-on-string morphology via the adjustments of polymer concentration and ambient humidity is sufficient to generate filter mediums with excellent efficiency and low airflow resistance for air filtration applications, which is also facile to be scaled up as no special equipment and costly chemicals are required.

Facile Functionalization via Plasma-Enhanced Chemical Vapor Deposition for the Effective Filtration of Oily Aerosol.

With the growing concern about the health impacts associated with airborne particles, there is a pressing need to design an effective filter device. The objective of this study is to investigate the effect of plasma-based surface modifications on static charges of electrospun filter media and their resulting filtration performance. Polystyrene (PS) electrospun web (ES) had inherent static charges of ~3.7 kV due to its electric field-driven process, displaying effective filtration performance. When oxygen species were created on the surface by the oxygen plasma process, static charges of electret media decreased, deteriorating the filter performance. When the web surface was fluorinated by the plasma-enhanced chemical vapor deposition (PECVD), the filtration efficiency against oily aerosol significantly increased due to the combined effect of decreased wettability and strong static charges (~−3.9 kV). Solid particles on the charged media formed dendrites as particles were attracted to other layers of particles, building up a pressure drop. The PECVD process is suggested as a facile functionalization method for effective filter design, particularly for capturing oily aerosol.

Dependence of the fiber diameter on quality factor of filters fabricated with meta-aramid nanofibers

Bag filters are generally used to remove particulate matter from the dust-laden flue gas exhausted from combustors. Recently, great effort has been expended to improve the performance of bag filters by coating the filter surface with nanofibers. In this study, meta-aramid nanofibers with high thermal durability were produced by an electrospinning process, and the effect of fiber diameter on the filter quality factor was theoretically and experimentally investigated. Electrospun filters with mean fiber sizes of 333 nm and 569 nm were successfully prepared by controlling the electrospinning parameters. The filters had high mechanical and chemical durability, as per the results of thermogravimetric analyzer (TGA), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), and a tensile strength analyses. In addition, the particle collection efficiency and pressure drop of the filters increased as the fiber diameter decreased. The filter quality factor, determined by the relationship between the collection efficiency and the pressure drop, increased slightly with the decrease in fiber diameter, although the experimental results were slightly different from the theoretical results.

Filter‐Through Method of Making Highly Efficient Polymer‐Clay Nanocomposite Membranes

AbstractElectrospun filter with hierarchical pore structure and variable pore diameter is used for the first time in making a flexible, strong, and high gas‐barrier membrane. A versatile, technical, benign processing method for the fabrication of highly filled (&gt;25 wt%) efficient gas‐barrier polymer membrane with perfectly aligned synthetic high‐aspect ratio layered silicate (clay) of variable and considerable thickness (up to 5 µm) is presented. This process combines advantageous features of an electrospun substrate like high porosity, variable pore size (typically &lt;5 µm), thermoplasticity and of an aqueous suspension of a synthetic clay consisting of single 1 nm thick layers with a huge median lateral extension (&gt;10 µm) in a layered structure. By simple and fast filtration, a gas‐barrier self‐assembled layer of variable and appropriate thickness is obtained on a mechanically stable thermoplastic electrospun filter support that subsequently can be laminated adhesively or via hot pressing, even in a multilayer structure, if required. The resulting composite membranes are flexible, strong, transparent, and show enhanced gas‐barrier properties.