Use Of Nanofibrous Membranes Research Articles

Electrospun Nanofibrous Membranes for Air Filtration: A Critical Review

Air filtration is an urgent global need because, in many countries and regions, the high concentration of inhalable suspended particles in the air is causing irreversible damage to human health. The use of nanofibrous membranes can help to reduce airborne particulate matter because of their large surface area, extremely porous structure, and adjustable pore size. However, despite their unique properties, the main drawbacks of nanofibre membranes are their poor mechanical properties. This review focuses on nanofibrous membranes prepared by electrospinning, a versatile technique in which the process parameters allow control of the morphology and dimensional characteristics of the nanofibres. Recent literature on air filtration is reviewed, focusing on the performance of materials such as pure or mixed polymers, organic–inorganic composites, and ‘green’ materials in the form of nanofibrous membranes. Finally, the recently proposed layered structures for nanofibre-based air filters are reviewed, offering the latest and most innovative solutions.

A Thermoplastic Elastomeric Nanofibrous Membrane as CFRP Modifier to Boost Both Delamination and Damping Performance

AbstractIn the present work, thermoplastic elastomeric nanofibers made up of a homogenous blend of nitrile butadiene rubber (NBR) and Ppolycaprolactone (CL), with 80% wt of rubbery component, are used to modify a carbon fiber reinforced polymer (CFRP) laminate with the aim of improving its delamination and damping behavior at the same time. Since the nanofibrous membrane is not chemically cross‐linked, the fibrous morphology is lost during composite curing owing to its melting. Nonetheless, the nanomodified CFRP displays an impressive ability to improve the delamination resistance in mode I and also an enhanced damping capacity at low temperature. The use of nanofibrous membranes allows for modification of specifically selected areas, thus maximizing the toughening and damping behavior where most required, without necessarily affecting the whole bulk of the resin. Both PCL and NBR components contribute to the final performance; however, the very high amount of rubber leads to a membrane difficult to handle whose final performance in CFRP modification is not superior to membranes up to 60% wt NBR that are instead more stable and easier to deal with. Overall, the proposed results are nonetheless very promising, taking into account also that the improved delamination resistance in mode I and enhanced damping are obtained without significantly sacrificing the weight and overall dimension of the obtained composite.

Indoor formaldehyde removal by catalytic oxidation, adsorption and nanofibrous membranes: a review

Indoor pollution of air by formaldehyde poses a serious threat to human health because formaldehyde causes illnesses and discomfort even at low levels, thus calling for abatement techniques. Techniques include absorption, physisorption, chemisorption, biological and botanical filtration, photocatalytic decomposition, membrane separation, plasma and catalytic oxidation. Here we review the principles, performances, advantages and disadvantages of these techniques, with focus on catalytic oxidation, adsorption and the use of nanofibrous membranes. Supported noble metal and metal oxide-based materials are efficient catalysts for oxidation. We present photocatalytic oxidation under UV, visible and solar light using composites. Chemisorption method is reviewed with focus on amino-containing adsorbents, conditions of temperature and relative humidity and surface properties. Nanofibrous membranes display high density of active sites for pollutant interactions and allow formaldehyde removal without leaching out of catalyst nanoparticles or adsorbents.

Dilute solvent welding: A quick and scalable approach for enhancing the mechanical properties and narrowing the pore size distribution of electrospun nanofibrous membrane

Major limitations to the practical use of nanofibrous membranes in water filtration are their weak mechanical properties and wide pore size distribution. This study describes a quick and scalable method to improve the mechanical properties and narrow the pore size distribution of nanofibrous membranes by welding the nanofibers at their junction points. The welding process involves a simple dilute solvent spraying step followed by heating, requiring only a few minutes. The polymer's solvent was diluted with a non-solvent to avoid excessive dissolution of the nanofibers. With that, the degree of welding can be controlled by the volume fraction of solvent, the heating temperature and heating temperature. Dilute solvent welding enhanced the mechanical properties of the nanofibrous membrane while slightly changed the fiber crystallinity and fiber size distribution. Furthermore, the membrane pore size distribution narrowed with welding while high porosity (~80%) was retained. In membrane distillation (MD) experiments, the welded nanofibrous membrane exhibited more robust MD performance than the pristine nanofibrous membrane with only slight decreases of vapor flux. This technique can be applied universally to treat both nanofibrous flat sheet and tubular membranes made from soluble polymers with their corresponding diluted solvents.

Efficient protein immobilization on polyethersolfone electrospun nanofibrous membrane via covalent binding for biosensing applications.

In this paper we introduce novel strategy for antibody immobilization using high surface area electrospun nanofibrous membrane based on ethyl-3-(3-dimethylaminopropyl)-carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling chemistry. To present the high performance of proposed biosensors, anti-staphylococcus enterotoxin B (anti-SEB) was used as a model to demonstrate the utility of our proposed system. Polymer solution of polyethersolfone was used to fabricate fine nanofibrous membrane. Moreover, industrial polyvinylidene fluoride membrane and conventional microtiter plate were also used to compare the efficiency of antibody immobilization. Scanning electron microscopy images were taken to study the morphology of the membranes. The surface activation of nanofibrous membrane was done with the help of O2 plasma. PES nanofibrous membrane with carboxyl functional groups for covalent attachment of antibodies were treated by EDC/NHS coupling agent. The quantity of antibody immobilization was measured by enzyme-linked immuno sorbent assay (ELISA) method. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopy was performed to confirm the covalent immobilization of antibody on membrane. Atomic force microscopy, scanning electron microscopy and invert fluorescence microscopy were used to analyze the antibody distribution pattern on solid surfaces. Results show that oxygen plasma treatment effectively increased the amount of antibody immobilization through EDC/NHS coupling chemistry. It was found that the use of nanofibrous membrane causes the improved detection signal of ELISA based biosensors in comparison to the standard assay carried out in the 96-well microtiter plate. This method has the potential to improve the ELISA-based biosensor and we believe that this technique can be used in various biosensing methods.

Electrospun nanofibrous PVDF–PMMA MF membrane in laboratory and pilot-scale study treating wastewater from Seoul Zoo

Polyvinylidene fluoride (PVDF) blended with polymethyl methacrylate (PMMA) was electrospun into nanofibrous membranes, which had a mean pore size of 0.45μm. The pure water permeability of the prepared membrane was higher compared to previous reports in which conventional cast membranes with equivalent mean pore size and contact angle were characterized for the purposes of domestic and industrial uses. Microscopic diagnoses were also conducted to characterize the physical and morphological natures of the nanofibrous membrane, which revealed that the prepared membrane was much smoother than conventional cast membranes. The increase in resistance to filtration was negligible up to 16days without membrane cleaning for filtration of the secondary effluent; however this was not the case when the membranes were used for bioreactors. Suspended solids in the secondary effluent were completely removed, and a 48% removal of chemical oxygen demand was also achieved. Pilot-scale testing of the electrospun nanofibrous PVDF–PMMA membrane was also conducted on secondary effluent from the Seoul Zoo wastewater treatment plant (12m3d−1). Our results revealed that the nanofibrous membrane has the potential to become a mainstream application in post-treatment of secondary effluent, which could lead us to explore the use of nanofibrous membranes for diverse applications.