Polyacrylonitrile Concentration Research Articles

Polyacrylonitrile and polyethersulfone based co-axial electrospun nanofibers for fluoride removal from contaminated stream

Coaxial electrospun polyacrylonitrile (PAN) and polyethersulfone (PES) based nanofibers were prepared and was used for filtration of fluoride from drinking water for the first time. Well defined fiber geometry was obtained at 1 ml/h of core polymer, i.e., PES flow rate, 1.4 ml/h of shell polymer, i.e., PAN flow rate, voltage of 22 kV, while the distance between the needle tip and the collector was 15–17 cm. Increase in bead like structure in fiber strands was observed with higher PAN concentration, while it decreased for lower PES concentration, thereby giving an optimum composition (6 wt% PAN and 10 wt% PES) for uniform fiber morphology. This nanofiber, abbreviated as N2 acted as an ultrafiltration membrane having permeability in the lower range, i.e., 0.5 × 10−11 m/s Pa and its fluoride removal efficacy was 46%. Fibers were also hydrophilic with considerable porous nature. Uptake of fluoride by this N2 nanofibers were evident from binding energy of 685.2 eV during XPS analysis. It is probable that nitrile and sulfone groups present in the core and shell of the nanofibers played an active in fluoride uptake, which was estimated as 110 mg/g at 298 K. Isoelectric point was in alkaline range which promoted negative fluoride ion uptake on positive nanofiber surface. Lead played higher masking effect in the uptake of fluoride in comparison to arsenic as coexisting ion. Dynamic cross flow filtration was also studied with this nanofiber in both synthetic and real life feed solution.

Design of parallel double-chain fibrous electrode using electrospinning technique for vanadium redox flow battery with boosted performance

This article proposes a parallel double-chain fibrous electrode structure with dual fibers of different diameters by electrospinning technique for vanadium redox flow battery to improve the battery performance. The larger diameter fibers contribute to the formation of larger pores, enhancing electrolyte flow and mass transfer. Meanwhile, the smaller diameter fibers provide abundant reaction sites. Different fiber diameters are fabricated by using precursor solutions with different concentration ratios. For a single concentration ratio electrode, as the concentration of PAN (Polyacrylonitrile) solution in syringe A increases, the performance of the battery significantly improves. The best performance is achieved by employing a concentration ratio of 20%:10%, i.e., ECF (Electrospun Carbon Fibers)-20%/10% electrode, at various current densities due to largest pore diameter and enough reaction sites. At current densities of 100 mA cm−2 and 200 mA cm−2, the ECF-20%/10% electrode achieves energy efficiencies of 88% and 80.5%, which are twice the energy efficiency of traditional carbon felt electrodes. Moreover, after 200 cycles, the battery capacity decay of ECF-20%/10% electrode only is 27.5%, which is 20.3% lower than that of the carbon felt electrode after 100 cycles. Dual concentration ratio electrode is also fabricated and found to show lower performance than the best single concentration ratio electrode for the reason that the second fabrication stage decreases the pore sizes.

Facile fabrication of organic superhydrophobic corn silk-derived cellulose acetate nanofiber for the effective sequestration of oil from oil-water mixture.

Oil spills and subsequent cleanup by oil-water separation remain a global concern. For the first time, corn silk-derived cellulose acetate (CSCA) and polyacrylonitrile (PAN) composite nanofiber are reported to create a superhydrophobic oil-water sequestration membrane. CA : PAN solutions with various PAN concentrations were evaluated for viscosity and conductivity. A CSCA nanofiber membrane was fabricated through electrospinning, which was superhydrophobic and oleophilic in water. Scanning electron microscope, energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis/differential scanning calorimetry were used to analyze the membrane's morphological features. CSCA nanofibers formed a highly spherical bead with a maximum contact angle of 156° (>120°) in pure water solutions, demonstrating their superhydrophobicity. This study found that membranes can remove oil from oil-water mixtures and emulsions, as gravity is the only force required for propelling the system. Mineral oil had the highest oil sorption capability (908%), while toluene had the lowest (664%). For mineral oil-water mixtures, the CSCA membrane has the greatest separation flux at a maximum of 442 L/m2/h and the best separation efficiency at up to 99.67%. These findings provide strong support for using an as-prepared CSCA nanofiber membrane as a viable reusable oil sorbent in oil spill cleaning.

Transformation of Specific Dispersion Interactions between Cellulose and Polyacrylonitrile in Solutions into Covalent Interactions in Fibers.

Morphological transformations in emulsions of cellulose and polyacrylonitrile (PAN) ternary copolymers containing acrylonitrile, methyl acrylate, and methylsulfonate comonomers in N-methylmorpholine-N-oxide were studied over the entire range of concentrations depending on temperature and intensity of the deformation action. Based on the morphological and rheological features of the system, the temperature-concentration range of spinnability of mixed solutions was determined, and composite fibers were spun. The fibers are characterized by a heterogeneous fibrillar texture. Studies of the structure of the fibers, carried out using X-ray diffraction analysis, revealed a decrease in cellulose crystallinity with an increase in the content of PAN. The study of the thermal properties of the obtained fibers, carried out using DSC, and chemical transformations in them in a wide temperature range by high-temperature diffuse reflection IR spectroscopy made it possible to reveal a new intense exothermic peak on the thermograms at 360 °C, which according to the IR spectra corresponds to the transformation of intermacromolecular physical interactions of the PAN and cellulose into covalent bonds between polymers. In addition, the ester groups found during the thermal treatment of the PAN part of the composite fibers in the pyrolysis zone can have a key effect on the process of their further carbonization.

Electrospun nanofiber mat of graphene/mesoporous silica composite for wastewater treatment

In this research, we fabricated the electrospun nanofibers based on functionalized porous graphene (FPG), modified SBA-15 (SBA/CuO), Polyvinylpyrrolidone (PVP), and Polyacrylonitrile (PAN). FPG, SBA/CuO, and PAN concentrations, and applied voltage were optimized to fabricate the nanofibers with the best morphology. The average diameter of optimized nanofibers was obtained at 124 ± 41 nm. A series of characterizations, including FE-SEM, EDX, AFM, FT-IR, XRD, TG-DTA, tensile and contact angle measurements were employed to study the structure and morphology of nanofibers. We fabricated a Nano-filter from nanofibers to remove some water pollutants including methylene blue, malachite green, potassium permanganate, copper, lead, and cadmium ions. The filtration performance of the proposed Nano-filter was examined under the optimum conditions (concentration, volume, and pH) for each of the water pollutants (R> 97%). The results of Nano-filter recycling showed that it could be reused up to 5 times with more than 90% efficiency. Experiments have demonstrated that Nano-filter has ideal performance in the removal of dyes and metal ions from factory wastewater. Besides, the static and dynamic adsorption capacities were explored, where methylene blue (112 mg/g) and lead ions (131 mg/g) had higher static states were higher than other dyes and metal ions.

Effect of mesophase pitch/polyacrylonitrile mixture as the core‐layer on the interphase region structure of coaxial polyacrylonitrile/mesophase pitch composite fibers

AbstractCoaxial composite fibers with a cortex of polyacrylonitrile (PAN) and a core layer of mesophase pitch (MP) and PAN have been prepared by the wet spinning method, formed in a mixed solution of N,N‐dimethylformamide and deionized water to optimize the composition of the core‐layer mixture. The XRD curves of the PAN/MP coaxial composite fibers only showed the crystalline and amorphous diffraction peaks of PAN. With increasing MP mass fraction in the mixed PAN/MP solution, the crystallinity of the coaxial composite fiber gradually decreased from 27.95% to 26.21%, because MP intermixed between the PAN macromolecules, weakening the interaction between the PAN molecular chains. In the core layer of the coaxial composite fibers, spherical MP particles were dispersed in the network structure of PAN. Different proportions of PAN/MP mixed solution will result in different core structure. The coaxial composite fiber consisted of a core layer with a low gray value, a transition layer with increasing gray value, and a cortex with a high gray value. From the core layer to the cortex, taking Group C as an example, the C content gradually decreased from 68.64% to 61.23% and the N content gradually increased from 13.68% to 22.19%, which was consistent with the gradual decrease of the MP content and the gradual increase of the PAN content. Gray‐value analysis, micro‐region EDS, and SEM showed that a transition layer structure formed at the junction of the cortex and core layer. The size and amplitude of the transition layer were related to the viscosity of the mixed PAN/MP solution, and high MP content in the mixed PAN/MP solution was conducive to formation of a stable and good interface structure.

Multistep structure evolution during the coagulation of PAN/DMSO solution studied by in-situ FTIR spectroscopy

Coagulation is the first step in the formation of the aggregation structure during the preparation of polyacrylonitrile (PAN) fiber, which has a significant effect on the mechanical properties of PAN precursor and its based carbon fiber. However, due to the rapid coagulation speed of the PAN/DMSO solution in the coagulation bath, research about the complex matter exchange and structural evolution during this process is still a challenging topic. In the present study, the PAN/DMSO solution was set in an environment with constant humidity to slow down the coagulation rate. In situ FTIR measurements combined with two-dimensional correlation analysis were used for the first time to study the detailed evolution of the intermolecular interaction and PAN chain conformation caused by the change of H2O, DMSO, and PAN content during coagulation. The results indicated that with the diffusion of H2O from the atmosphere to PAN/DMSO solution, hydrogen bonds between H2O and DMSO were gradually generated, which led to a chemical environmental change around PAN chains and promoted the dissociation of PAN and DMSO. After that, the parallel-oriented –CN groups promoted the conformation change of the PAN chains.

Electrospinning micro-nanofibers immobilized aerobic denitrifying bacteria for efficient nitrogen removal in wastewater

Electrospinning micro-nanofibers with exceptional physicochemical properties and biocompatibility are becoming popular in the medical field. These features indicate its potential application as microbial immobilized carriers in wastewater treatment. Here, aerobic denitrifying bacteria were immobilized on micro-nanofibers, which were prepared using different concentrations of polyacrylonitrile (PAN) solution (8%, 12% and 15%). The results of diameter distribution, specific surface area and average pore diameter indicated that 15% PAN micro-nanofibers with tighter surface structure were not suitable as microbial carriers. The bacterial load results showed that the cell density (OD600) and total protein of 12% PAN micro-nanofibers were 107.14% and 106.28% higher than those of 8% PAN micro-nanofibers. Subsequently, the 12% PAN micro-nanofibers were selected for aerobic denitrification under the different C/N ratios (1.5–10), and stable performance was obtained. Bacterial community analysis further manifested that the micro-nanofibers effectively immobilized bacteria and enriched bacterial structure under the high C/N ratios. Therefore, the feasibility of micro-nanofibers as microbial carriers was confirmed. This work was of great significance for promoting the application of electrospinning for microbial immobilization in wastewater treatment.

Cerium Oxide Nanoparticles/Polyacrylonitrile Nanofibers as Impervious Barrier against Viral Infections.

Using face masks is one of the protective measures to reduce the transmission rate of coronavirus. Its massive spread necessitates developing safe and effective antiviral masks (filters) applying nanotechnology. Novel electrospun composites were fabricated by incorporating cerium oxide nanoparticles (CeO2 NPs) into polyacrylonitrile (PAN) electrospun nanofibers that can be used in the future in face masks. The effects of the polymer concentration, applied voltage, and feeding rate during the electrospinning were studied. The electrospun nanofibers were characterized using SEM, XRD, FTIR, and tensile strength testing. The cytotoxic effect of the nanofibers was evaluated in the Vero cell line using the MTT colorimetric assay, and the antiviral activity of the proposed nanofibers was evaluated against the human adenovirus type 5 (ADV-5) respiratory virus. The optimum formulation was fabricated with a PAN concentration of 8%, w/v loaded with 0.25%, w/v CeO2 NPs with a feeding rate of 26 KV and an applied voltage of 0.5 mL/h. They showed a particle size of 15.8 ± 1.91 nm and a zeta potential of -14 ± 0.141 mV. SEM imaging demonstrated the nanoscale features of the nanofibers even after incorporating CeO2 NPs. The cellular viability study showed the safety of the PAN nanofibers. Incorporating CeO2 NPs into these fibers further increased their cellular viability. Moreover, the assembled filter could prevent viral entry into the host cells as well as prevent their replication inside the cells via adsorption and virucidal antiviral mechanisms. The developed cerium oxide nanoparticles/polyacrylonitrile nanofibers can be considered a promising antiviral filter that can be used to halt virus spread.

Relation between microscopic structure and macroscopic properties in polyacrylonitrile-based lithium-ion polymer gel electrolytes.

Polymer gel electrolytes (PGE) have seen a renewed interest in their development because they have high ionic conductivities but low electrochemical degradation and flammability. PGEs are formed by mixing a liquid lithium-ion electrolyte with a polymer at a sufficiently large concentration to form a gel. PGEs have been extensively studied, but the direct connection between their microscopic structure and macroscopic properties remains controversial. For example, it is still unknown whether the polymer in the PGE acts as an inert, stabilizing scaffold for the electrolyte or it interacts with the ionic components. Here, a PGE composed of a prototypical lithium-carbonate electrolyte and polyacrylonitrile (PAN) is pursued at both microscopic and macroscopic levels. Specifically, this study focused on describing the microscopic and macroscopic changes in the PGE at different polymer concentrations. The results indicated that the polymer-ion and polymer-polymer interactions are strongly dependent on the concentration of the polymer and the lithium salt. In particular, the polymer interacts with itself at very high PAN concentrations (10% weight) resulting in a viscous gel. However, the conductivity and dynamics of the electrolyte liquid components are significantly less affected by the addition of the polymer. The observations are explained in terms of the PGE structure, which transitions from a polymer solution to a gel, containing a polymer matrix and disperse electrolyte, at low and high PAN concentrations, respectively. The results highlight the critical role that the polymer concentration plays in determining both the macroscopic properties of the system and the molecular structure of the PGE.

Improving the Physical Properties of Nanofibers Prepared by Electrospinning from Polyvinyl Chloride and Polyacrylonitrile at Low Concentrations

In this study, both polyvinyl chloride (PVC) and polyacrylonitrile (PAN) were dissolved in dimethyl formaldehyde (DMF) with 8 wt. % concentrations at 25 : 75, 50 : 50, and 75 : 25 of PVC: PAN blending. For the investigation of the homogeneity and compatibility of mixture polymer solutions, it is examined by rheological properties such as viscosity, shear stress, shear rate, and calculation of the flow behavior index, while the investigation of the stability and high density of nanofibers without beads used field-emission scanning electron microscopy (FE-SEM), Fourier transform near-infrared spectroscopy (FT-NIR), X-ray diffraction (XRD), and differential scanning calorimetry-thermogravimetric analysis (DSC-TGA). The results show that blending of PAN with PVC leads to improving of the electro spun ability of PVC with more stability, and the mean nanofiber diameter was90.873±40.82 nmat 25 : 75 PVC: PAN. Moreover, mechanical properties are ultimate tensile strength and modulus of elasticity decreasing with decreasing the blending ration from pure PVC to 75 : 25 PVC: PAN nanofibers by 71% and 83%, respectively, while the elongation at break increases by 79%, and decomposition temperatures decreased from 451.96 to 345.38°C when changing the PVC content from pure PVC to 25 : 75 PVC: PAN. On the other hand, changing of the nanofiber behavior from hydrophobicity to hydrophilic increased the PAN content in PVC: PAN blends. Furthermore, the low interaction between the chains of polymers and the crystallinity (%) and crystalline size (nm) of blend nanofibers slightly decreased compared to the pure polymers. According to all tests, the 25: 75 PVC: PAN was the best blending ratio, which gave a more stable nanofiber produced at low concentrations and more compatible between the PVC and PAN.

Controlling the physical properties of polyacrylonitrile by strontium hexaferrite nanoparticles

AbstractThe formulation of polymer with embedded magnetic nanoparticles results in promising nanocomposites for smart and analytical applications. Nanocomposites containing polyacrylonitrile (PAN) and different mass contents of strontium hexaferrite (SFO) were prepared using the casting method. The nanocomposite samples were characterized by using different techniques such as field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. Dielectric investigations of SFO/PAN nanocomposites showed that the permittivity and conductivity are considerably enhanced as the content of SFO increased. Optical properties revealed that the absorption and transmittance spectra were significantly affected by adding SFO nanoparticles to the PNA polymer matrix. To investigate the magnetic properties of the nanocomposite samples, the vibrating sample magnetometer was used. The magnetic hysteresis loops illustrated the ferromagnetic nature of SFO/PAN nanocomposites. Different magnetic parameters were given, and they depend on the content of PAN in the nanocomposites.

The effect of polymeric drag reducing agent on pressure drop reduction in circular pipes: Experimental and statistical investigation

The present work deals with investigating the effect of adding Polyacrylonitrile (PAN) as a drag-reducing agent on the water flow’s hydraulic performance within horizontal smooth circular pipes experimentally and statistically. Several experiments were performed under various operating circumstances such as fluid flow rates at the 6,8,10 l/min for preparing turbulent flow regimes, concentrations of 25,100, 300 ppm of PAN, and inner pipe diameters of 1/2,3/4 in, and temperatures of 30, 40, and 50 °C. The maximum percentage of drag reduction (DR%) was 56 at a concentration of 300 ppm, the flow rate of 6 l/min, temperature of 30 °C and the diameter of 3/4 in. Using the Taguchi method, the results were statistically analyzed. The maximum estimated DR% value was 40.187%, and the error between the predicted and experimental values was about 10%. Moreover, the PAN concentration had a contribution of 96.5% in the polymeric solution DR. Finally, there was a new correlation to predict friction coefficient in terms of the Prandtle-Karman relation with the newly set slope as a linear function of polymer concentration. There was an excellent consistency between this correlation and the experimental data.

Tailoring the Morphology and Performance of Polyacrylonitrile Ultrafiltration Membranes for Produced Water Treatment via Solvent Mixture Strategy

AbstractThe separation performance of membranes is highly dependent on their morphology and microstructure. The present study aims to tailor the characteristics of asymmetric polyacrylonitrile (PAN) ultrafiltration membranes by adopting a solvent mixture strategy, combining dimethylformamide (DMF) and N‐methyl‐2‐pyrrolidone (NMP) for produced water treatment. The ternary phase diagram was used for better analysis of the microstructural changes from the thermodynamics point of view. Using a solvent mixture containing more DMF (i.e., 75 %) and increasing the PAN concentration in the dope were effective in improving the solution viscosity and promoting delayed demixing. As a result, finger‐like macrovoids were suppressed to some extent and the internal morphology of the membranes was transformed into a sponge‐like structure, accompanied by a reduction in the overall membrane porosity and mean pore size.

Effect of Polymer Concentration on the Photocatalytic Membrane Performance of PAN/TiO2/CNT Nanofiber for Methylene Blue Removal through Cross-Flow Membrane Reactor

A photocatalytic membrane combining photocatalyst and membrane technology based on polyacrylonitrile (PAN) and TiO2/CNT has been developed. Such combination is to overcome fouling formation on the membrane, thus prolonging the membrane lifetime and enhancing the efficiency on the waste treatment. PAN nanofiber was prepared by electrospinning method. The precursor solution was dissolved PAN and dispersed TiO2/CNT in N,N-Dimethylformamide (DMF). PAN concentration in the precursor solution was varied at 4.5, 5.5, 6.5, 7.5, and 8.5%. The effect of PAN concentration on the fiber morphology and pore size was discussed. The performance of the resulted membrane on methylene blue (MB) removal was also investigated on a cross-flow system. SEM images of the resulted membrane identified that PAN nanofiber was successfully fabricated with random orientation. The PAN 6.5% showed the highest diffraction intensity of the anatase crystalline phase of TiO2. The additions of CNT and TiO2 lead to the formation of a cluster of beads as confirmed by TEM. Increasing the concentration of PAN increased the fiber diameter from 206 to 506 nm, slightly decreased the surface area and pore size, respectively, from 32.739 to 21.077 m2.g−1 and from 6.38 to 4.75 nm. The PAN/TiO2/CNT nanofibers show type IV of the adsorption-desorption N2 isotherms with the H1 hysteresis loops. Membrane PAN/TiO2/CNT at PAN concentration of 6.5% shows the optimum performance on the MB color removal by maintaining the percentage of rejection (%R) at 90% for 240 min and permeability of 750 LMH. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

The structure and property of polyacrylonitrile-based microfiltration membranes for oil-water emulsion separation

The polyacrylonitrile (PAN)-based microfiltration membranes material was prepared used waste polyacrylonitrile fibers as the raw material. The PAN membranes have two different structure, the surface layer is finger pore structure, below layer is cavernous pore structure with the porosity is 85.92%. The PAN membrane shows super strong hydrophilicity (high water permeability) and ultra low adhesion of underwater oil (good oilresistance) under different pH values and different surfactants. The flux of PAN membranes is 1952.63 L•m−2• H−1 • bar−1, the oil retention ability is 99.14% when the film thickness was 100 μm, the PAN concentration was 7%, and the alkali treatment time was 1 h. The PAN membrane is an environmentally friendly material, have good application potential for oil-water emulsion separation and recycling of waste oil. Preparation of separation and filtration materials provides a good way to recycle waste PAN fibers and has potential practical value in oil-water separation field.

Fabrication of polyacrylonitrile-Li1.6Mn1.6O4 composite nanofiber flat-sheet membranes via electrospinning method as effective adsorbents for Li+ recovery from salt-lake brine

In this paper, polyacrylonitrile (PAN) as the binder and Li1.6Mn1.6O4 as the powder were used to prepare the composite nanofiber flat-sheet membrane-type adsorbent (ESNM-H) via the electrospinning method. The influence factor on membrane adsorption capacity for Li+ were investigated, such as the concentration of PAN, precursor content, and membrane thickness. When the content of PAN and Li1.6Mn1.6O4 were 10 wt% and 18 wt%, respectively, the equilibrium adsorption capacity for Li+ on ESNM-H with the thickness of 164 ± 4 μm was 1328 mg/m2, and the actual adsorption capacity of powder H1.6Mn1.6O4 incorporated in the nanofiber membrane remained 92% of the unsupported powder. In the artificial salt-lake brine, the adsorption selectivity of ESNM-H for Li+ was higher to other interfering ions (Na+, Ca2+, K+ and Mg2+). After eight cycles, the adsorption capacity of ESNM-H decreased by 8%. The ESNM-H exhibited the better long-term stability. The ESNM-H packed column was enriched with Li+ from 100 mg/L to 726 mg/L after ten consecutive dynamic adsorption–desorption cycles. The overall results show that the composite nanofiber flat-sheet membrane-type adsorbent fabricated via the electrospinning method has potential applications and recyclability in adsorbing Li+ from salt-lake brine.

Electro-spinning of highly-aligned polyacrylonitrile nano-fibres with continuous spooling

This paper reports on a new configuration for producing highly-aligned electro-spun fibres that can be produced on a static substrate or one where it is hauled off and spooled continuously to enable the production of continuous lengths. The fixture consists of a Vee-shaped polytetrafluorethylene shield at 60° with a 1 cm wide integral rectangular base that is mounted on a copper disk with a 10 cm diameter. Specified concentrations of polyacrylonitrile in dimethyl sulfoxide were electro-spun on to a strip of cellulose paper. In the static setup, approximately 91% of the fibres were deposited to within 3°. When the spooling rig was used, a tape of the cellulose paper was hauled off at 0.07 mm/min, 78% of the fibres were aligned to within 3°. Simulations of the conventional and Vee-shield electro-spinning setups were undertaken and they provided corroboration for the experimental observations with regard to the mechanism responsible for fibre alignment. The feasibility of using this technique to produce 0°/− 45°/+ 45° stacked layers of aligned fibre preform is demonstrated.

Paper Doped with Polyacrylonitrile Fibres Modified with 10,12-Pentacosadiynoic Acid.

This work reports a modification of a fibrous cellulose material (paper) by the addition of polyacrylonitrile (PAN) fibres doped with 10,12–pentacosadiynoic acid (PDA). The fibres are sensitive to ultraviolet (UV) light. When the paper containing PAN–PDA is irradiated with UV light it changes colour to blue as a consequence of interaction of the light with PDA. The colour intensity is related to the absorbed dose, content of PAN–PDA fibres in the paper and the wavelength of UV radiation. The features of the paper are summarised after reflectance spectrophotometry and scanning microscopy analyses. All the properties of the modified paper were tested in accordance with adequate ISO standards. Moreover, a unique method for assessing the unevenness of the paper surface and the quality of printing was proposed by using a Python script (RGBreader) for the analysis of RGB colour channels. The modification applied to the paper can serve as a paper security system. The modified paper can act also as a UV radiation indicator.

Catalytic oxidation of NO at low concentrations by carbon nanofibers near room temperature

Polyacrylonitrile (PAN) nanofibers obtained by electrospinning were used to prepare PAN-based carbon nanofibers (PCNFs) by pre-oxidation, carbonization and high-temperature treatment in NH3. The PCNFs were used for the removal of low concentrations of NO (5×10−5) near room temperature (20 °C) by catalytic oxidation. Results indicated that the PCNFs had high porosity and a large specific surface area, and their diameters could be regulated by changing the PAN concentration. The smaller the diameter of the PCNFs the more micropores were developed, and the larger the specific surface area the better the adsorption and catalytic oxidation performance.