Electrospun Polyacrylonitrile Nanofibrous Membranes Research Articles

Electrospun Nanofiber Supported Nano/Mesoscale Covalent Organic Frameworks Boost Iodine Sorption.

Covalent Organic Frameworks (COFs) are benchmark materials for iodine sorption, but their use has largely been confined to crystalline bulk forms. In this state, COFs face diffusion limitations leading to slow sorption kinetics. To address this, a series of [2+3] imine-linked COFs with varying particle sizes and morphologies (mesospheres, nanoflowers, and bulk) is synthesized. Reducing particle size (from 826±48 to 412±22 nm) and adding surface protrusions in COF mesospheres improved iodine adsorption capacity (7.6 to 8.5 g g⁻¹), kinetics (K80%, 0.61 to 0.76 g g⁻¹ h⁻¹), and chemisorption efficiency. Notably, solvothermally synthesized (120°C, 5 d) crystalline bulk COF with accessible porous surfaces exhibited faster kinetics (K80%, 1.13 g g⁻¹ h⁻¹) than nano/mesoCOFs.This implies nano- and mesoCOFs exhibit surface aggregation that passivates their external binding sites and hinders iodine diffusion and mass transfer.To prevent this, morphologically controlled COF particles are immobilized onto electrospun polyacrylonitrile nanofibrous membranes via in situ growth strategy, creating a hierarchical structure that improved iodine diffusion pathways. This modification increased iodine sorption kinetics by 98%-153% and strengthened the charge-transfer process compared to COF powders.

Algae-Enhanced Electrospun Polyacrylonitrile Nanofibrous Membrane for High-Performance Short-Chain PFAS Remediation from Water.

As a short-chain PFAS (per- and polyfluoroalkyl substance), GenX was produced in recent years to replace traditional long-chain PFASs, such as perfluorooctanoic acid (PFOA). However, GenX turns out to be more toxic than people originally thought, posing health risks as a persistent environmental pollutant. In this research, for the first time, we incorporated chlorella, a single-celled green freshwater microalga that grows worldwide, with polyacrylonitrile (PAN) in equal amounts in electrospun nanofibers and studied the capability of the electrospun PAN/Algae bicomponent nanofibrous membrane (ES(PAN/Algae)) to bind and remove GenX from water. The incorporation of algae demonstrated a synergistic effect and significantly improved the GenX removal efficiency of the nanofibrous membrane. The maximum GenX removal capacity reached 0.9 mmol/g at pH 6, which is significantly higher than that of most of the reported GenX adsorbents as well as activated carbon. The GenX removal mechanism was investigated and discussed by using water contact angle, zeta potential, FTIR, and XPS techniques. This research demonstrated the potential to make highly efficient adsorbent/filter materials from common and economic materials to practically remediate short-chain PFASs from various water bodies.

Fluorine-Free Hydrophobic Modification and Waterproof Breathable Properties of Electrospun Polyacrylonitrile Nanofibrous Membranes.

Waterproof breathable functional membranes have broad application prospects in the field of outdoors textiles. The fluorine-containing microporous membranes of the mainstream functional products easily cause harm to the environment, and thus, the fluorine-free environmental nanofibrous membranes are an important development direction for functional membranes. In this subject, the electrospun polyacrylonitrile nanofibrous membranes were first hydrophobically modified by amino functional modified polysiloxane (AMP), followed by in situ cross-linking modified with 4, 4'-methyl diphenylene diisocyanate (MDI). The fluorine-free modification by AMP altered the surface of the membranes from hydrophilic to hydrophobic, and greatly improved the waterproof properties with the hydrostatic pressure reaching to 87.6 kPa. In addition, the formation of bonding points and the in situ preparation of polyuria through the reaction between the isocyanate in MDI and the amino group in AMP, could improve the mechanical properties effectively. When using AMP with the concentration of 1 wt% and MDI with the concentration of 2 wt%, the relatively good comprehensive performance was obtained with good water resistance (93.8 kPa), modest vapor permeability (4.7 kg m-2 d-1) and air permeability (12.7 mm/s). Based on these testing data, the modified nanofibrous membranes had excellent waterproof and breathable properties, which has future potential in outdoor sports apparel.

Highly efficient self-cleaning of heavy polyelectrolyte coated electrospun polyacrylonitrile nanofibrous membrane for separation of oil/water emulsions with intermittent pressure

Electrospun polyacrylonitrile fiber membranes (EPFMs) are coated with multilayer films that assembled by layer-by-layer (LBL) technique through alternating deposition of polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA). To obtain the heavy polyelectrolyte (PE) layer consisting of PAH and PAA, single pH value was replaced with alternative pH during LBL processes stabilizing the PAH/PAA layer without significant desorption. The heavy zwitterionic-like LBL coating of PAH/PAA film on the EPFM surface presents complete oil repellency while wetted in water (i.e., underwater superoleophobicity), so that allows to efficiently remove oil stains on dry EPFM by water. Removal of oil staining from a fibrous surface with high contact area demands to build up extremely strong bonding with water in both pristine and oil-wetted states. The PAH/PAA-coated EPFMs exhibit excellent self-cleaning from fibers even already wetted by oil. Generally, there is a maximum permeation volume during oil/water emulsion separation, because the blocked oil accumulates as a hydrophobic layer to block water passing through. These PAH/PAA-coated EPFMs are resilient to oil accumulation with intermittent pressure during the oil/water separation to remain the high permeation flux (over 30,000 L m−2 h−1 bar−1), still an pressing challenge in this area.

Ultralong Life Organic Sodium Ion Batteries Using a Polyimide/Multiwalled Carbon Nanotubes Nanocomposite and Gel Polymer Electrolyte

Organic cathode materials are of great interest for application in batteries due to their abundant availability and environmental compatibility. An approach to make long chain molecules of these organic materials in order to overcome the problem of dissolution in a liquid electrolyte (LE) and incorporate a highly conducting material to enhance the poor electric conductivity of these materials would be of great research interest. In this work, a novel polyimide (PI)/multiwalled carbon nanotube (MWCNT) nanocomposite is prepared as the cathode material for organic Na-ion batteries (NIBs), via a two-step imidization reaction using perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and diaminopropane (DAP) to form an insoluble PI. The MWCNT in the composite serves as the conductive channel to maximize the utilization of the active material in the electrode. Furthermore, a three-dimensional fiber network is prepared from an electrospun polyacrylonitrile nanofibrous membrane and used as a gel polymer electrol...

An Investigation on bilayer structures of electrospun polyacrylonitrile nanofibrous membrane and cellulose membrane used as filtration media for apple juice clarification

Nanofibrous membrane has a potential to use in filtration technology with electrospinning as one of the techniques used in synthesizing nanofibers. Polyacrylonitrile (PAN) nanofibrous membranes with various fibers diameters were electrospun by varying its precursor solution concentration. The average fibers diameters of the PAN nanofibrous membranes obtained from the precursor solution concentrations of 6, 9, 12, and 14 wt% were 341, 534, 1274, and 2107 nm, respectively. Filtration media for apple juice clarification were bilayer-structured membranes made of PAN nanofibrous membranes on commercial cellulose microfibrous membranes. It has been shown that the reduction of apple juice color or turbidity performed by the cellulose microfibrous membrane was well enhanced by the presence of the PAN nanofibrous membrane in the bilayer-structured membrane. In addition, the apple-juice color and turbidity reductions increased with decreasing the average fibers diameter of the PAN nanofibrous membrane. Furthermore, the PAN nanofibrous membrane also helped the cellulose microfibrous membrane in the bilayer-structured membrane enhance the reductions of total phenols, protein, and glucose of the apple juice.

Design of electrospun polyacrylonitrile nanofiber–coated nonwoven structure for sound absorption

Acoustic felts are commonly used in white goods. Bearing that into mind, this paper aims to enhance sound absorption behavior of such felts, in particular, within the low and medium frequency ranges. In doing so, wool and jute felt samples were coated with electrospun polyacrylonitrile nanofibrous membrane. These nanocoated felts were studied in terms of their sound absorption performance, air permeability, and surface morphology. The results indicated that the air permeability of the felts could be drastically decreased by coating with nanofibers, which was required for better acoustic performance of felt‐like structures. Moreover, the samples having higher amount polyacrylonitrile nanofibers tended to demonstrate better sound absorbency.

Electrospun polyacrylonitrile nanofibrous membranes with varied fiber diameters and different membrane porosities as lithium-ion battery separators

In this study, nine types of polyacrylonitrile (PAN) nanofibrous membranes with varied fiber diameters and different membrane porosities are prepared by electrospinning followed by hot-pressing. Subsequently, these membranes are explored as Li-ion battery (LIB) separators. The impacts of fiber diameter and membrane porosity on electrolyte uptake, Li+ ion transport through the membrane, electrochemical oxidation potential, and membrane performance as LIB separator (during charge/discharge cycling and rate capability tests of a cathodic half-cell) have been investigated. When compared to commercial Celgard PP separator, hot-pressed electrospun PAN nanofibrous membranes exhibit larger electrolyte uptake, higher thermal stability, wider electrochemical potential window, higher Li+ ion permeability, and better electrochemical performance in LiMn2O4/separator/Li half-cell. The results also indicate that the PAN-based membrane/separator with small fiber diameters of 200–300nm and hot-pressed under high pressure of 20MPa surpasses all other membranes/separators and demonstrates the best performance, leading to the highest discharge capacity (89.5mAhg−1 at C/2 rate) and cycle life (with capacity retention ratio being 97.7%) of the half-cell. In summary, this study has revealed that the hot-pressed electrospun PAN nanofibrous membranes (particularly those consisting of thin nanofibers) are promising as high-performance LIB separators.

Thiol-functionalized electrospun polyacrylonitrile nanofibrous membrane for highly efficient removal of mercury ions

Mercury ions pollution has threatened people's health. Conventional nano-adsorbents suffer from the aggregation and later separation, novel adsorbent with high adsorption performance and easy recover properties is highly needed. In this study, thiol-functionalized electrospun polyacrylonitrile (PAN) nanofibrous membrane was obtained and used as easy recovery adsorbent for mercury ions. The morphologies and chemical composition were studied using SEM, TEM, ATR-FTIR, XRD and XPS. The results indicated that mercury adsorption performance was pH sensitive and the optimal pH range for mercury ions adsorption was about 5.5⿿6.0. The adsorption equilibrium reached within 25min, and the adsorption process can be described using the pseudo-second-order model. Isotherm data fitted well to the Langmuir isotherm model. After adsorption of mercury ions, the thiol-functionalized nanofibrous membranes can be regenerated, and the adsorption efficiency maintained up to 90% after three times of usage.

Effect of Nano-Sized Ceramic Fillers on the Performance of Polymer Electrolytes Based on Electrospun Polyacrylonitrile Nanofibrous Membrane for Lithium Ion Batteries

Effect of Nano-Sized Ceramic Fillers on the Performance of Polymer Electrolytes Based on Electrospun Polyacrylonitrile Nanofibrous Membrane for Lithium Ion Batteries

Immobilization of catalases on amidoxime polyacrylonitrile nanofibrous membranes

AbstractAmidoxime polyacrylonitrile (AOPAN) nanofibrous membranes were generated by the reaction between electrospun polyacrylonitrile nanofibrous membranes and hydroxylamine hydrochloride. AOPAN nanofibrous membranes were further modified by Fe(III) chelation for immobilizing catalases with coordination bonds. The surface morphologies of the nanofibrous membranes and immobilized catalases were observed by field emission scanning electron microscopy. Chelation of Fe(III) onto AOPAN nanofibrous membranes was studied by the Langmuir isothermal adsorption model. It was found that the maximum amount of coordinated Fe(III) (qm) was 4.5045 mmol g−1 (dry nanofibrous membranes) and the binding constant (Kl) was 0.0698 L mmol−1. The amounts of immobilized enzymes were determined by the method of Bradford. Kinetic parameters were analyzed for both immobilized and free catalases. The value of Vmax (7122.6 µmol mg−1 min−1) for the immobilized catalases was smaller than that for the free catalases (9203.2 µmol mg−1 min−1), and the Km for the immobilized catalases was larger. The immobilized catalases showed better resistance to pH and temperature change than the free catalases, and the storage stability of immobilized catalases was higher than that of free catalases. As for reusability, the immobilized catalases retained 71% of their activity after eight repeated uses. © 2012 Society of Chemical Industry

Electrospun polyacrylonitrile nanofibrous membranes for chitosanase immobilization and its application in selective production of chitooligosaccharides

Polyacrylonitrile nanofibrous membranes (PANNFM) were prepared by electrospinning from 10wt.% of PAN solution and its surface was modified by amidination reaction. A new chitosan degrading enzyme from Aspergillus sp. was covalently immobilized on PANNFM. Immobilization efficiency of 80% was achieved by activating PANNFM surface for 30min followed by 2h treatment with enzyme solution. The optimum temperature and pH for immobilized enzyme were 50°C and 5.8, respectively. The immobilized chitosanase retained >70% activity after ten repeated batch reaction and could be stored up to 60days at 4°C with minor loss in activity. Chitosan hydrolysis using different substrates were studied using immobilized chitosanase in batch conditions. Continuous selective production of chitooligosaccharides (dimer to hexamer) by changing the temperature was achieved by PANNFM-chitosanase.

Hydrolysis of microalgae cell walls for production of reducing sugar and lipid extraction

In this study, cell walls of microalgae were hydrolyzed for the production of reducing sugar by cellulase, which was immobilized onto an electrospun polyacrylonitrile (PAN) nanofibrous membrane. Since the nitrile groups of the PAN membrane were activated by the amidination reaction and covalent binding to the amino groups of the cellulase, electrospun PAN nanofibrous membranes with a high specific surface area were applied as supports for the immobilization. Under the optimal hydrolysis conditions, the immobilized cellulase performed its hydrolyzing conversion at 62%, and the hydrolysis yield remained at 40% after five times of reuse. Additionally, microalgal lipid extraction efficiency increased to around 56% from 32% dramatically after cell wall hydrolysis. These results demonstrate the efficacy and feasibility of the proposed applications in hydrolysis process followed with lipid extraction.