The efficient adsorption of radioactive iodine(^(129)I and^(131)I)as nuclear waste is of great importance.Polymer nanocomposites consist of metal-organic frameworks(MOFs)developing for various pollutions sorption and ...The efficient adsorption of radioactive iodine(^(129)I and^(131)I)as nuclear waste is of great importance.Polymer nanocomposites consist of metal-organic frameworks(MOFs)developing for various pollutions sorption and separation have attracted much attention.This study reports the fabrication of magnetic polyacrylonitrile(PAN)/zeolitic imidazolate frameworks(ZIF-8)nanocomposites,PAN/ZIF-8(x%)/Fe_(3)O_(4),x=30 and 50,as iodine capture adsorbents.The PAN/ZIF-8(x%)/Fe_(3)O_(4)nanocomposite beads were fabricated via the phase inversion method,and their potential for iodine capture and separation in solution and vapor was investigated through UV-vis and weighing methods,respectively.Also,antibacterial activity of the as-prepared beads was assessed against E.coil and S.aureus.The as-fabricated compounds were studied by various techniques such as Fourier-transform infrared,X-ray diffraction,scanning electron microscope,energy-dispersive X-ray spectroscopy mapping,transmission electron microscope,N_(2)adsorption isotherm,and vibrating sample magnetometer.The iodine capture results showed that the efficiency of nanocomposites is remarkably higher than the pure PAN beads.Additionally,the asprepared nanocomposite adsorbents displayed higher capture capacities for iodine vapor(1524-4345mg·g^(-1))than iodine solution(187-295 mg·g^(-1)).The as-obtained magnetic nanocomposites can be successfully separated from polluted media by simple filtration or an external magnet,regenerated through washing with ethanol,and reused.Fast capturing,high sorption capacity,rapid separation,and good reusability make the PAN/ZIF-8(x%)/Fe_(3)O_(4)nanocomposites highly effective adsorbents for the separation of iodine from wastewater.Additionally,PAN/ZIF-8(50%)/Fe_(3)O_(4)bead can be considered as a potential new antibacterial agent for water and wastewater treatment.展开更多
In this study, the effect of combining different molecular domains on single platform has been reported that revealed a proper packing and interpenetration of fullerene spheres with the monomeric species. The fabricat...In this study, the effect of combining different molecular domains on single platform has been reported that revealed a proper packing and interpenetration of fullerene spheres with the monomeric species. The fabricated IPN system exhibits hydrophobic behavior in nature. An interpenetrating polymer network (IPN) of fullerene-based poly (methyl hydro siloxane) (PMHS) and polyacrylonitrile (PAN) was prepared. The synthesized polymer network was characterized using infrared (IR) spectroscopy, differential scanning calorimetric analysis (DSC), and scanning electron microscopic (SEM) technique. The IPN was analyzed by IR spectroscopy, which depicts presence of fullerene at 500 cm<sup>−1</sup> and 1632 cm<sup>−1</sup>, presence of PHMS at 1050 cm<sup>−1</sup>, 1250 cm<sup>−1</sup>, 2225 cm<sup>−1</sup>, and 3000 cm<sup>−1</sup> and presence of PAN at 3077 cm<sup>−1</sup>, 1299 cm<sup>−1</sup>, 1408 cm<sup>−1</sup> and 2083 cm<sup>−1</sup>. Shifting in band positions indicated the interpenetration of the reacting species. DSC endotherm showed crystalline peak (T<sub>c</sub>) at 117˚C, which indicated the crystalline nature of the synthesized IPN. The absence of T<sub>g</sub> peak and clear observable T<sub>c</sub> peak revealed crystalline behavior of polymeric network. The microstructure of the polymer network was observed by SEM technique, which revealed transparent and dual-phase morphology of the IPN surface. The fluorescent emission spectra of polymeric network were recorded on a spectrofluorometer which revealed fluorescent excitation and emission spectra of the IPN. The Emission spectra generated by radiative decay of excitations exhibit a maximal peak at 450 nm, suggesting that the synthesized IPN nanosheets were typically high-intensity blue light emitting materials. The FTIR investigations revealed multiple non-covalent interactions achieved by polymerization with physical anchoring on the polymeric network surfaces. Such interactions can be recognized as the driving force for the fabrication of hydrophobic flexible silicon-based materials with a self-cleansing action.展开更多
Polyacrylonitrile preoxided fibre PANOF is an intermediate in carbon fibre preparation. Thequality of PANOF is closely related to the property and structure of carbon fibre. In this paper, thermal mechanical analysis(...Polyacrylonitrile preoxided fibre PANOF is an intermediate in carbon fibre preparation. Thequality of PANOF is closely related to the property and structure of carbon fibre. In this paper, thermal mechanical analysis(TMA), thermogravimetric analysis(TGA), swell-ing differential scanning calorimetry(SDSC)and X-ray photoelectron spectroscopy(XPS)wereused to study the increase in tenacity of PANOF from the precursor treated with cuprous salt It has been discovered that the cuprous salt reacts strongly with the uncyclized CN of PANOF,resulting in an increase in the tenacity of PANOF by 30%. The results shwo that the cause of thistenacity improvement is the formation of coordinated complex. Cu^+is the central ion, and PANOFthe ligand. It is due to the coordinate bond that the network structure is formed from uncyclizedCN of PANOF. Therefore the tenacity of PANOF is remarkably increased.展开更多
This paper describes the preparation of a membrane of polyacrylonitrile(PAN)and its corresponding membrane coated with polyaniline(PANI)for the adsorption of heavy metal ions.Scanning electron microscopy micrographs r...This paper describes the preparation of a membrane of polyacrylonitrile(PAN)and its corresponding membrane coated with polyaniline(PANI)for the adsorption of heavy metal ions.Scanning electron microscopy micrographs revealed that all the membranes exhibited nanofibrous morphology.The prepared membranes were characterized by Fourier transform infrared spectroscopy(FTIR).The prepared membranes were used as an adsorbent for hazardous heavy metal ions Pb^(2+) and Cr_(2)O^(2-)_(7).The adsorption capacity and the removal efficiency of the membranes were examined as function of the initial adsorbate concentration and pH of the medium.Coated membranes with PANI showed better adsorption performance and their direct current(DC)conductivities were correlated to heavy metal ion concentrations.Adsorption isotherms were also performed,and the adsorption process was tested according to the Langmuir and Freundlich models.The regeneration and reuse of the prepared membranes to re-adsorb heavy metal ions were also investigated.The enhancement in adsorption performance and reusability of PANI-coated membranes in comparison with non-coated ones is fully discussed.The results show that the maximum adsorption capacities of lead and chromate ions on the PANI-coated membranes are 290.12 and 1202.53 mg/g,respectively.展开更多
A cheap and simple sample preparation method, consisting of a dispersive solid-phase method and an adsorbent, activated carbon decorated PAN nanofibers, was employed and used for the extraction of antibiotics(ciproflo...A cheap and simple sample preparation method, consisting of a dispersive solid-phase method and an adsorbent, activated carbon decorated PAN nanofibers, was employed and used for the extraction of antibiotics(ciprofloxacin, danofloxacin, and enrofloxacin) in wastewater. Electrospun PAN nanofibers that were decorated with activated carbon produced from waste tires were used as the solid phase and the antibiotics analyzed by using high-performance liquid chromatography. Parameters such as pH, mass of adsorbent(MA),extraction volume(EV), and extraction time(ET) were optimized owing to their potential effect on the extraction of antibiotics from water. The recovery of all antibiotics was satisfactory, in the range of 90%–99%.The limits of detection and quantification were 0.05, 0.11, 0.20, and 0.53, 1.21, 2.17 mg/L, respectively. The precision was determined from the repeatability and reproducibility and expressed as the intra-day(n=20)and inter-day(n=5) precision. The intra-day and inter-day precision was reported in terms of the percentage relative standard deviation, which was 3% and 4%, respectively. The adsorption capacity of the activated carbon-decorated PAN nanofibers was satisfactory, and the reusability of the adsorbent was impressive when reused ten times. The accuracy of the dispersive solid phase extraction(DSPE) was validated by spike recovery tests; the results proved the reliability and efficiency of adsorbing antibiotics from wastewater. Finally, the proposed method was applied to wastewater samples collected from a wastewater treatment plant, which included influent, secondary, and effluent wastewater.展开更多
A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbo...A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol.The as-treated carbon fibers were then graphitized at 2 400 ℃ for 2 h.The structural changes were characterized by X-ray diffractometry(XRD),Raman spectroscopy,scanning electron microscopy(SEM) and high-resolution transmission electronic microscopy(HRTEM).The results show that much better graphitization can be achieved in the presence of Mo-B,with an interlayer spacing(d002) of 0.335 8 nm and a crystalline size(Lc) of 28 nm.展开更多
Sulfurized polyacrylonitrile(SPAN)as a promising cathode material for lithium sulfur(Li-S)batteries has drawn increasing attention for its improved electrochemical performance in carbonate-based electrolyte.However,th...Sulfurized polyacrylonitrile(SPAN)as a promising cathode material for lithium sulfur(Li-S)batteries has drawn increasing attention for its improved electrochemical performance in carbonate-based electrolyte.However,the relatively poor electronic and ionic conductivities of SPAN limit its high-rate and lowtemperature performances.In this work,a novel one-dimensional nanofiber SPAN(SFPAN)composite is developed as the cathode material for Li-S batteries.Benefitting from its one-dimensional nanostructure,the SFPAN composite cathode provides fast channels for the migration of ions and electronics,thus effectively improving its electrochemical performance at high rates and low temperature.As a result,the SFPAN maintains a high reversible specific capacity^1200 mAh g−1 after 400 cycles at 0.3 A g−1 and can deliver a high capacity of^850 mAh g−1 even at a high current density of 12.5 A g−1.What is more,the SFPAN can achieve a capacity of^800 mAh g−1 at 0℃and^1550 mAh g−1 at 60℃,thus providing a wider temperature range of applications.This work provides new perspectives on the cathode design for high-rate lithium-sulfur batteries.展开更多
High chemical reactivity, large volume changes, and uncontrollable lithium dendrite growth have always been the key problems of lithium metal anodes.Coating has been demonstrated as an effective strategy to protect th...High chemical reactivity, large volume changes, and uncontrollable lithium dendrite growth have always been the key problems of lithium metal anodes.Coating has been demonstrated as an effective strategy to protect the lithium metal.In this work, the effects of polyacrylonitrile(PAN)-based coatings on electrodeposited lithium have been studied.Our results show that a PAN coating layer provides uniform and dendrite-free lithium deposition as well as better cycling performance with carbonate electrolyte.Notably, heat treatment of the PAN coating layer promotes the formation of larger deposit particle size and higher coulombic efficiency(85%).The compact coating layer of heat-treated PAN with a large Young modulus(82.7 GPa) may provide stable protection for the active lithium.Improved homogeneity of morphology and mechanical properties of heat-treated PAN contribute to the larger deposit particles.This work provides new feasibility to optimize the polymer coating through rational modification of polymers.展开更多
The effect of additives CaCl\-2 and CaCl\-2/H\-2O on the properties of polyacrylonitrile(PAN) ultrafiltration(UF) membranes prepared by phase inversion process was studied. The dissolving capacity of the casting solut...The effect of additives CaCl\-2 and CaCl\-2/H\-2O on the properties of polyacrylonitrile(PAN) ultrafiltration(UF) membranes prepared by phase inversion process was studied. The dissolving capacity of the casting solution for CaCl\-2 was enhanced by the addition of H\-2O. The membranes are characterized in terms of the pure water flux and molecular weight cut\|off(MWCO). The addition of CaCl\-2 or CaCl\-2/H\-2O to the casting solution increases the resulting membrane permeability.展开更多
Sulfurized polyacrylonitrile(SPAN)represents a unique class of cathode material for lithium sulfur(Li-S)batteries as it eradicates the polysulfides shuttling issue in carbonate-based electrolyte.However,due to the ess...Sulfurized polyacrylonitrile(SPAN)represents a unique class of cathode material for lithium sulfur(Li-S)batteries as it eradicates the polysulfides shuttling issue in carbonate-based electrolyte.However,due to the essential chemical S-linking and organic nature of SPAN,the active mass percentage and rate capability are two bottleneck issues preventing its ultimate deployment outside of laboratories.In the current work,aiming to endow both the charge conductivity and catalytic activity to SPAN for maximizing the redox kinetics of S conversion,a freestanding nanofibrous SPAN cathode embedding conductive CNTs and atomically dispersed Co centers is fabricated via multivariate electrospinning.While the CNTs enable dramatically enhancing the fiber conductivity and generating mesoscopic porosity for facilitating charge and mass transportation,the cross-linking of SPAN by Co-N_(4) S motifs creates extra charge conduction pathways and further serves as the catalytic active sites for expediting redox S conversion.As a result,an extraordinary Li-SPAN performance is achieved with a high specific capacity up to 1856 mAh g^(-1)@0.2 C,a superb rate capability up to 10 C,and an ultra-long battery life up to 1500 cycles@1 C.Consequently,our study here provides insights into the adoption of coordination chemistry to maximize the sulfur utilization by ensuring a more complete redox conversion from SPAN to Li2 S,and vice versa.展开更多
The effects of the components of solution for membrane casting and preparation conditions on the membrane performances are studied in this paper. Polyacrylonitrile (PAN) was used as polymer and DMAC as solvent. The ul...The effects of the components of solution for membrane casting and preparation conditions on the membrane performances are studied in this paper. Polyacrylonitrile (PAN) was used as polymer and DMAC as solvent. The ultrafiltration (UF) membranes whose cut-off of molecular weight is 150000 and flux of pure water reaches 150-200 ml/(cm2·h) were prepared by selecting proper components of solution for membrane casting and membrane preparation conditions.展开更多
Different polyacrylonitrile （PAN） precursor fibers that displayed various thermal properties were studied by using differential scanning calorimetry （DSC）. Results showed that some commercial PAN precursor fibers ...Different polyacrylonitrile （PAN） precursor fibers that displayed various thermal properties were studied by using differential scanning calorimetry （DSC）. Results showed that some commercial PAN precursor fibers displayed double separated peaks and these fibers were of high quality because of their process stability during their conversion to carbon fibers of high performance. Some fabrication processes, such as spinning, drawing, could not apparently change the DSC features of a PAN precursor fiber. It was concluded that the thermal properties of a PAN precursor fiber was mainly determined from its comonomer content type and compositions.展开更多
A new oxadiazole-functionalized polyacrylonitrile fiber(PANAOF)was successfully fabricated by immobilizing the organic molecule 2-chloromethyl-5-phenyl-1,3,4-oxadiazole on aminated fiber(PANAF).The fibers were charact...A new oxadiazole-functionalized polyacrylonitrile fiber(PANAOF)was successfully fabricated by immobilizing the organic molecule 2-chloromethyl-5-phenyl-1,3,4-oxadiazole on aminated fiber(PANAF).The fibers were characterized completely by Fourier-transform infrared spectroscopy,elemental analysis,X-ray diffraction,and X-ray photoelectron spectroscopy techniques.Compared with PANAF,PANAOF showed a higher adsorption capability for Hg^2+ions in aqueous solutions.The functionalized fiber PANAOF exhibited a highly selective adsorption for Hg^2+when coexisting with other metal ions viz.Pb^2+,Cd^2+,Cu^2+,Zn^2+,Ni^2+,Co^2+,Cr^3+,Ca^2+,and Mg^2+.The PANAOF presented the best adsorption capacity for Hg^2+at pH 5.Moreover,the adsorption experimental data fit well with the pseudo-second-order kinetic model and Langmuir isotherm.Notably,the PANAOF almost retained its original adsorption capacity(112 mg/g)after five cycles,indicating its excellent reusability in practical applications.展开更多
Polyacrylonitriles （PANs） ware synthesized both by atom transfer radical polymerization （ATRP） anti free radical polymerization in ionic liquid 1 - buty - 3 - methylimidazolium chloride （[bmim]Cl）. [bmim]Cl demo...Polyacrylonitriles （PANs） ware synthesized both by atom transfer radical polymerization （ATRP） anti free radical polymerization in ionic liquid 1 - buty - 3 - methylimidazolium chloride （[bmim]Cl）. [bmim]Cl demonstrates to be a preferable solvent for ATRP of acrylonitrile （AN）. The polymerization maintains the usual advantages of ATRP with molecular weight agrees well with theoretical value and low polydispersity （PDI = 1.15）. It is also shown the higher conversion and lower molecular weight dispersion in ionic liquid than in dimethylformamide （DMF）. From FTIR and NMR analysis, it is confirmed that the chemical structures of PANs synthesized in [bmim]Cl were identical with that obtained in DMF. In atom transfer radical polymerization, the methine and cyan carbon atoms in isotactic configuration for PAN produced in [bmim] Cl have a configuration consisting of about 55.5% isotactic diads. It is higher than that obtained in DMF which is 52.2%. So, ionic liquid has effect on the stereostructure of PANs. Further analysis of ^13C NMR spectra indicated that the isotacticity of PAN synthesized by free radical polymerization was lower than that of PAN prepared by ATRP, although both of them were random in stereoregularity. Besides the pentad tacticities of PANs also suggested that the sequence distributions of them all obey Bernoulli statistics.展开更多
The method of preparing the multi-walled carbon nanotubes (MWNTs)-polyacrylonitriIe (PAN) composite fibers is described and the effects of draw ratio on the mechanical properties of CNT/PAN fibers have also been discu...The method of preparing the multi-walled carbon nanotubes (MWNTs)-polyacrylonitriIe (PAN) composite fibers is described and the effects of draw ratio on the mechanical properties of CNT/PAN fibers have also been discussed. The results show that the degrees of MWNTs dispersion in the polymer matrix have much effect on the mechanical properties.展开更多
Dynamic viscoelastic properties of polyacrylonitrile(PAN)/DMSO/H2O solutions with different H2O contents were studied as a function of temperature.These PAN solutions gradually became gel with decreasing temperature.T...Dynamic viscoelastic properties of polyacrylonitrile(PAN)/DMSO/H2O solutions with different H2O contents were studied as a function of temperature.These PAN solutions gradually became gel with decreasing temperature.The sol-gel transition took place at a critical gel temperature,at which the scaling law of G'(ω)～G″(ω)∝ωn held,allowing an accurate determination of the critical gel temperature by means of the frequency independence of the loss tangent.The gel point of PAN solutions increases with increasing H2O content.The scaling exponent n(=0.86) at the gel point is confirmed to be universal for PAN gels,which is independent of temperature,suggesting the similarity of the fractal structure in the critical PAN gels.展开更多
To improve the hydrophilicity of polyacrylonitrile-based membranes, sugar moieties were incorporated into acrylonitrile-based copolymers via the radical copolymerization of α-allyl glucoside(AG) with acrylonitrile(AN...To improve the hydrophilicity of polyacrylonitrile-based membranes, sugar moieties were incorporated into acrylonitrile-based copolymers via the radical copolymerization of α-allyl glucoside(AG) with acrylonitrile(AN) with 2,2′-azobis-iso-butyronitrile(AIBN) as the initiator in dimethyl sulphoxide(DMSO). It was found that the yield increased with the increase of the initiator concentration and reaction time, while it decreased with the increase of the monomer molar ratio of AG to AN. Raising the AG proportion in the monomer mixture resulted in the increase of the AG content in the copolymer. M_v of the copolymers decreased with increasing the AG monomer fraction in feed. The copolymers were fabricated into dense membranes and their surface properties were studied by means of the water contact angle measurement and platelet adhesion tests. It was found that the static water contact angle on the membrane decreased significantly from 70° to 33° with the increase of the AG content. The adhesive number of platelets on the membrane surface also decreased significantly with increasing AG content in the copolymers. These results demonstrate that the hydrophilicity and biocompatibility of the acrylonitrile-based copolymer membranes could be improved efficiently by the copolymerization of acrylonitrile with vinyl carbohydrates.展开更多
Different mass percent polyacrylonitrile （PAN）-polyethylene oxide （PEO） gels were prepared and irradiated by an electron beam （EB） with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were...Different mass percent polyacrylonitrile （PAN）-polyethylene oxide （PEO） gels were prepared and irradiated by an electron beam （EB） with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were analysed by using Fourier transform infrared spectrum, gel fraction and ionic conductivity （IC） measurement. The results show that the gel is crosslinked by EB irradiation, the crosslinking degree rises with the increasing EB irradiation dose （ID） and the mass percents of both PAN and PEO contribute a lot to the crosslinking; in addition, EB irradiation can promote the IC of PAN-PEO gels. There exists an optimum irradiation dose, at which the IC can increase dramatically. The IC changes of the PAN-PEO gels along with ID are divided into three regions： IC rapidly increasing region, IC decreasing region and IC balanced region. The cause of the change can be ascribed to two aspects, gel capturing electron degree and crosslinking degree. By comparing the IC-ID curves of different mass percents of PAN and PEO in gel, we found that PAN plays a more important role for gel IC promotion than PEO, since addition of PAN in gel causes the IC-ID curve sharper, while addition of PEO in gel causes the curve milder.展开更多
Polymeric nanofibers are a promising technology to protect the metal surfaces from corrosion.Through the literature search,the use of polyacrylonitrile nanofibres(PANNFs)as a corrosion inhibitor coating for aluminum a...Polymeric nanofibers are a promising technology to protect the metal surfaces from corrosion.Through the literature search,the use of polyacrylonitrile nanofibres(PANNFs)as a corrosion inhibitor coating for aluminum alloys has not been evaluated.This work includes the development of a new,lightweight,high surface area and efficient coating of PANNFs that produced using electrospinning process to resist the corrosion of aluminum alloys(AA5083)which immersed in 0.6 M NaCl at alkaline medium(pH=12)and acidic medium(pH=1)at a range of temperatures(293–323)K.The PANNFs coating was successfully deposited on AA 5083 specimens,where these samples were considered as a collector electrode in the electrospinning process.The corrosion experiments of the aluminum alloys coated with PANNFs before and after immersion in both corrosive mediums were investigated using cyclic potential polarization(CPP).The results confirmed that the PANNFs coating was able to protect the surface of the aluminum specimens from corrosion,by reducing the corrosion current and increasing the surface polarization resistance,thus reducing the corrosion rate.The protection efficiency was found in the alkaline medium 98.8%while in the acidic medium 83.3%.So,it was in both mediums decreased with the increase in temperature.The shape,distribution and size of the polymeric nanofibers that formed the coating were also examined using field emission scanning electron microscopy(FE-SEM)and the percentages of the structural components of these fibers were detected using the X-ray dispersion spectroscopy(EDS).The surface of aluminum specimens was completely covered by PANNFs.These electrospun nanofibers have worn out and lined up spacing after immersion in the corrosive mediums.The diameters average of PANNFs was found to be about 200 and 150 nm before and after immersion,respectively.展开更多
The Lonversion of polyacrylonitrile(PAN)fibre to carbon fibre consists of an oxidative stabili-zation process in which the PAN fibre is heated between 200-300℃ in air to give a thermally co-herent structure.The struc...The Lonversion of polyacrylonitrile(PAN)fibre to carbon fibre consists of an oxidative stabili-zation process in which the PAN fibre is heated between 200-300℃ in air to give a thermally co-herent structure.The structural changes of PAN fibres during stabilization have been investigatedusing Fourier Transform Infrared Spectroscopy(FTIR)and Differential Scanning Calorimetry(DSC).An attempt has also been made to follow the conversion of the structure using Ramanspectroscopy as a complementary technique.The FTIR spectra of the fibres subjected to variousdegree of heat treatment show a continuous decrease in nitrile absorption and a simultaneous in-crease in intensity of the C=N and/or C=C bands as the stabilization proceeds.A conversion ra-tio(CR)is defined as the intensity of the C=N and/or C=C bands relative to that of the nitrilegroups.The exotherm present in the DSC experiments was observed to weaken progressively dur-ing the stabilization process.It is confirmed that the original PAN structure is dissipating and thenew ladder polymer is being formed.展开更多
基金financial support(SCU.SC1400.29011)from the Shahid Chamran University of Ahvaz。
文摘The efficient adsorption of radioactive iodine(^(129)I and^(131)I)as nuclear waste is of great importance.Polymer nanocomposites consist of metal-organic frameworks(MOFs)developing for various pollutions sorption and separation have attracted much attention.This study reports the fabrication of magnetic polyacrylonitrile(PAN)/zeolitic imidazolate frameworks(ZIF-8)nanocomposites,PAN/ZIF-8(x%)/Fe_(3)O_(4),x=30 and 50,as iodine capture adsorbents.The PAN/ZIF-8(x%)/Fe_(3)O_(4)nanocomposite beads were fabricated via the phase inversion method,and their potential for iodine capture and separation in solution and vapor was investigated through UV-vis and weighing methods,respectively.Also,antibacterial activity of the as-prepared beads was assessed against E.coil and S.aureus.The as-fabricated compounds were studied by various techniques such as Fourier-transform infrared,X-ray diffraction,scanning electron microscope,energy-dispersive X-ray spectroscopy mapping,transmission electron microscope,N_(2)adsorption isotherm,and vibrating sample magnetometer.The iodine capture results showed that the efficiency of nanocomposites is remarkably higher than the pure PAN beads.Additionally,the asprepared nanocomposite adsorbents displayed higher capture capacities for iodine vapor(1524-4345mg·g^(-1))than iodine solution(187-295 mg·g^(-1)).The as-obtained magnetic nanocomposites can be successfully separated from polluted media by simple filtration or an external magnet,regenerated through washing with ethanol,and reused.Fast capturing,high sorption capacity,rapid separation,and good reusability make the PAN/ZIF-8(x%)/Fe_(3)O_(4)nanocomposites highly effective adsorbents for the separation of iodine from wastewater.Additionally,PAN/ZIF-8(50%)/Fe_(3)O_(4)bead can be considered as a potential new antibacterial agent for water and wastewater treatment.
文摘In this study, the effect of combining different molecular domains on single platform has been reported that revealed a proper packing and interpenetration of fullerene spheres with the monomeric species. The fabricated IPN system exhibits hydrophobic behavior in nature. An interpenetrating polymer network (IPN) of fullerene-based poly (methyl hydro siloxane) (PMHS) and polyacrylonitrile (PAN) was prepared. The synthesized polymer network was characterized using infrared (IR) spectroscopy, differential scanning calorimetric analysis (DSC), and scanning electron microscopic (SEM) technique. The IPN was analyzed by IR spectroscopy, which depicts presence of fullerene at 500 cm<sup>−1</sup> and 1632 cm<sup>−1</sup>, presence of PHMS at 1050 cm<sup>−1</sup>, 1250 cm<sup>−1</sup>, 2225 cm<sup>−1</sup>, and 3000 cm<sup>−1</sup> and presence of PAN at 3077 cm<sup>−1</sup>, 1299 cm<sup>−1</sup>, 1408 cm<sup>−1</sup> and 2083 cm<sup>−1</sup>. Shifting in band positions indicated the interpenetration of the reacting species. DSC endotherm showed crystalline peak (T<sub>c</sub>) at 117˚C, which indicated the crystalline nature of the synthesized IPN. The absence of T<sub>g</sub> peak and clear observable T<sub>c</sub> peak revealed crystalline behavior of polymeric network. The microstructure of the polymer network was observed by SEM technique, which revealed transparent and dual-phase morphology of the IPN surface. The fluorescent emission spectra of polymeric network were recorded on a spectrofluorometer which revealed fluorescent excitation and emission spectra of the IPN. The Emission spectra generated by radiative decay of excitations exhibit a maximal peak at 450 nm, suggesting that the synthesized IPN nanosheets were typically high-intensity blue light emitting materials. The FTIR investigations revealed multiple non-covalent interactions achieved by polymerization with physical anchoring on the polymeric network surfaces. Such interactions can be recognized as the driving force for the fabrication of hydrophobic flexible silicon-based materials with a self-cleansing action.
文摘Polyacrylonitrile preoxided fibre PANOF is an intermediate in carbon fibre preparation. Thequality of PANOF is closely related to the property and structure of carbon fibre. In this paper, thermal mechanical analysis(TMA), thermogravimetric analysis(TGA), swell-ing differential scanning calorimetry(SDSC)and X-ray photoelectron spectroscopy(XPS)wereused to study the increase in tenacity of PANOF from the precursor treated with cuprous salt It has been discovered that the cuprous salt reacts strongly with the uncyclized CN of PANOF,resulting in an increase in the tenacity of PANOF by 30%. The results shwo that the cause of thistenacity improvement is the formation of coordinated complex. Cu^+is the central ion, and PANOFthe ligand. It is due to the coordinate bond that the network structure is formed from uncyclizedCN of PANOF. Therefore the tenacity of PANOF is remarkably increased.
文摘This paper describes the preparation of a membrane of polyacrylonitrile(PAN)and its corresponding membrane coated with polyaniline(PANI)for the adsorption of heavy metal ions.Scanning electron microscopy micrographs revealed that all the membranes exhibited nanofibrous morphology.The prepared membranes were characterized by Fourier transform infrared spectroscopy(FTIR).The prepared membranes were used as an adsorbent for hazardous heavy metal ions Pb^(2+) and Cr_(2)O^(2-)_(7).The adsorption capacity and the removal efficiency of the membranes were examined as function of the initial adsorbate concentration and pH of the medium.Coated membranes with PANI showed better adsorption performance and their direct current(DC)conductivities were correlated to heavy metal ion concentrations.Adsorption isotherms were also performed,and the adsorption process was tested according to the Langmuir and Freundlich models.The regeneration and reuse of the prepared membranes to re-adsorb heavy metal ions were also investigated.The enhancement in adsorption performance and reusability of PANI-coated membranes in comparison with non-coated ones is fully discussed.The results show that the maximum adsorption capacities of lead and chromate ions on the PANI-coated membranes are 290.12 and 1202.53 mg/g,respectively.
基金National Research Foundation (NRF, grant no. SFH14073184214) for providing financial support
文摘A cheap and simple sample preparation method, consisting of a dispersive solid-phase method and an adsorbent, activated carbon decorated PAN nanofibers, was employed and used for the extraction of antibiotics(ciprofloxacin, danofloxacin, and enrofloxacin) in wastewater. Electrospun PAN nanofibers that were decorated with activated carbon produced from waste tires were used as the solid phase and the antibiotics analyzed by using high-performance liquid chromatography. Parameters such as pH, mass of adsorbent(MA),extraction volume(EV), and extraction time(ET) were optimized owing to their potential effect on the extraction of antibiotics from water. The recovery of all antibiotics was satisfactory, in the range of 90%–99%.The limits of detection and quantification were 0.05, 0.11, 0.20, and 0.53, 1.21, 2.17 mg/L, respectively. The precision was determined from the repeatability and reproducibility and expressed as the intra-day(n=20)and inter-day(n=5) precision. The intra-day and inter-day precision was reported in terms of the percentage relative standard deviation, which was 3% and 4%, respectively. The adsorption capacity of the activated carbon-decorated PAN nanofibers was satisfactory, and the reusability of the adsorbent was impressive when reused ten times. The accuracy of the dispersive solid phase extraction(DSPE) was validated by spike recovery tests; the results proved the reliability and efficiency of adsorbing antibiotics from wastewater. Finally, the proposed method was applied to wastewater samples collected from a wastewater treatment plant, which included influent, secondary, and effluent wastewater.
基金Project(2006CB600903) supported by the National Basic Research Program of China
文摘A novel carbon fiber pretreatment was proposed.Polyacrylonitrile(PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface,and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly dispersed Mo-B sol.The as-treated carbon fibers were then graphitized at 2 400 ℃ for 2 h.The structural changes were characterized by X-ray diffractometry(XRD),Raman spectroscopy,scanning electron microscopy(SEM) and high-resolution transmission electronic microscopy(HRTEM).The results show that much better graphitization can be achieved in the presence of Mo-B,with an interlayer spacing(d002) of 0.335 8 nm and a crystalline size(Lc) of 28 nm.
基金supported by the National Natural Science Foundation of China(Grant nos.21773077,51632001,and 51532005)the Ministry of Science and Technology“973”program(Grant No.2015CB258400)the National Key R&D Program of China(2018YFB0905400)。
文摘Sulfurized polyacrylonitrile(SPAN)as a promising cathode material for lithium sulfur(Li-S)batteries has drawn increasing attention for its improved electrochemical performance in carbonate-based electrolyte.However,the relatively poor electronic and ionic conductivities of SPAN limit its high-rate and lowtemperature performances.In this work,a novel one-dimensional nanofiber SPAN(SFPAN)composite is developed as the cathode material for Li-S batteries.Benefitting from its one-dimensional nanostructure,the SFPAN composite cathode provides fast channels for the migration of ions and electronics,thus effectively improving its electrochemical performance at high rates and low temperature.As a result,the SFPAN maintains a high reversible specific capacity^1200 mAh g−1 after 400 cycles at 0.3 A g−1 and can deliver a high capacity of^850 mAh g−1 even at a high current density of 12.5 A g−1.What is more,the SFPAN can achieve a capacity of^800 mAh g−1 at 0℃and^1550 mAh g−1 at 60℃,thus providing a wider temperature range of applications.This work provides new perspectives on the cathode design for high-rate lithium-sulfur batteries.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51822211 and 51802342)the State Grid Technology Project,China(Grant No.DG71-17-010)
文摘High chemical reactivity, large volume changes, and uncontrollable lithium dendrite growth have always been the key problems of lithium metal anodes.Coating has been demonstrated as an effective strategy to protect the lithium metal.In this work, the effects of polyacrylonitrile(PAN)-based coatings on electrodeposited lithium have been studied.Our results show that a PAN coating layer provides uniform and dendrite-free lithium deposition as well as better cycling performance with carbonate electrolyte.Notably, heat treatment of the PAN coating layer promotes the formation of larger deposit particle size and higher coulombic efficiency(85%).The compact coating layer of heat-treated PAN with a large Young modulus(82.7 GPa) may provide stable protection for the active lithium.Improved homogeneity of morphology and mechanical properties of heat-treated PAN contribute to the larger deposit particles.This work provides new feasibility to optimize the polymer coating through rational modification of polymers.
文摘The effect of additives CaCl\-2 and CaCl\-2/H\-2O on the properties of polyacrylonitrile(PAN) ultrafiltration(UF) membranes prepared by phase inversion process was studied. The dissolving capacity of the casting solution for CaCl\-2 was enhanced by the addition of H\-2O. The membranes are characterized in terms of the pure water flux and molecular weight cut\|off(MWCO). The addition of CaCl\-2 or CaCl\-2/H\-2O to the casting solution increases the resulting membrane permeability.
基金supported by the National Natural Science Foundation of China(No.21805201)the NSFC-NRF China-Korea International Joint Research Project(No.51911540473)+1 种基金the Postdoctoral Research Foundation of China(No.2018T110544 and No.2017 M611899)the support by Suzhou Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies。
文摘Sulfurized polyacrylonitrile(SPAN)represents a unique class of cathode material for lithium sulfur(Li-S)batteries as it eradicates the polysulfides shuttling issue in carbonate-based electrolyte.However,due to the essential chemical S-linking and organic nature of SPAN,the active mass percentage and rate capability are two bottleneck issues preventing its ultimate deployment outside of laboratories.In the current work,aiming to endow both the charge conductivity and catalytic activity to SPAN for maximizing the redox kinetics of S conversion,a freestanding nanofibrous SPAN cathode embedding conductive CNTs and atomically dispersed Co centers is fabricated via multivariate electrospinning.While the CNTs enable dramatically enhancing the fiber conductivity and generating mesoscopic porosity for facilitating charge and mass transportation,the cross-linking of SPAN by Co-N_(4) S motifs creates extra charge conduction pathways and further serves as the catalytic active sites for expediting redox S conversion.As a result,an extraordinary Li-SPAN performance is achieved with a high specific capacity up to 1856 mAh g^(-1)@0.2 C,a superb rate capability up to 10 C,and an ultra-long battery life up to 1500 cycles@1 C.Consequently,our study here provides insights into the adoption of coordination chemistry to maximize the sulfur utilization by ensuring a more complete redox conversion from SPAN to Li2 S,and vice versa.
文摘The effects of the components of solution for membrane casting and preparation conditions on the membrane performances are studied in this paper. Polyacrylonitrile (PAN) was used as polymer and DMAC as solvent. The ultrafiltration (UF) membranes whose cut-off of molecular weight is 150000 and flux of pure water reaches 150-200 ml/(cm2·h) were prepared by selecting proper components of solution for membrane casting and membrane preparation conditions.
基金supported by the National Natural Science Foundation of China under grant No.59783002by the Natural Science Foundation of Henan under grant Nos.200510465008 and 0523021200.
文摘Different polyacrylonitrile （PAN） precursor fibers that displayed various thermal properties were studied by using differential scanning calorimetry （DSC）. Results showed that some commercial PAN precursor fibers displayed double separated peaks and these fibers were of high quality because of their process stability during their conversion to carbon fibers of high performance. Some fabrication processes, such as spinning, drawing, could not apparently change the DSC features of a PAN precursor fiber. It was concluded that the thermal properties of a PAN precursor fiber was mainly determined from its comonomer content type and compositions.
基金supported by the National Natural Science Foundation of China (Nos.21777111 and 21572156)
文摘A new oxadiazole-functionalized polyacrylonitrile fiber(PANAOF)was successfully fabricated by immobilizing the organic molecule 2-chloromethyl-5-phenyl-1,3,4-oxadiazole on aminated fiber(PANAF).The fibers were characterized completely by Fourier-transform infrared spectroscopy,elemental analysis,X-ray diffraction,and X-ray photoelectron spectroscopy techniques.Compared with PANAF,PANAOF showed a higher adsorption capability for Hg^2+ions in aqueous solutions.The functionalized fiber PANAOF exhibited a highly selective adsorption for Hg^2+when coexisting with other metal ions viz.Pb^2+,Cd^2+,Cu^2+,Zn^2+,Ni^2+,Co^2+,Cr^3+,Ca^2+,and Mg^2+.The PANAOF presented the best adsorption capacity for Hg^2+at pH 5.Moreover,the adsorption experimental data fit well with the pseudo-second-order kinetic model and Langmuir isotherm.Notably,the PANAOF almost retained its original adsorption capacity(112 mg/g)after five cycles,indicating its excellent reusability in practical applications.
基金Science and Technology Commission of Shanghai Municipality fund (No.04JC14011)Shanghai Municipal Education Commission (No. DAWN Project) fund
文摘Polyacrylonitriles （PANs） ware synthesized both by atom transfer radical polymerization （ATRP） anti free radical polymerization in ionic liquid 1 - buty - 3 - methylimidazolium chloride （[bmim]Cl）. [bmim]Cl demonstrates to be a preferable solvent for ATRP of acrylonitrile （AN）. The polymerization maintains the usual advantages of ATRP with molecular weight agrees well with theoretical value and low polydispersity （PDI = 1.15）. It is also shown the higher conversion and lower molecular weight dispersion in ionic liquid than in dimethylformamide （DMF）. From FTIR and NMR analysis, it is confirmed that the chemical structures of PANs synthesized in [bmim]Cl were identical with that obtained in DMF. In atom transfer radical polymerization, the methine and cyan carbon atoms in isotactic configuration for PAN produced in [bmim] Cl have a configuration consisting of about 55.5% isotactic diads. It is higher than that obtained in DMF which is 52.2%. So, ionic liquid has effect on the stereostructure of PANs. Further analysis of ^13C NMR spectra indicated that the isotacticity of PAN synthesized by free radical polymerization was lower than that of PAN prepared by ATRP, although both of them were random in stereoregularity. Besides the pentad tacticities of PANs also suggested that the sequence distributions of them all obey Bernoulli statistics.
文摘The method of preparing the multi-walled carbon nanotubes (MWNTs)-polyacrylonitriIe (PAN) composite fibers is described and the effects of draw ratio on the mechanical properties of CNT/PAN fibers have also been discussed. The results show that the degrees of MWNTs dispersion in the polymer matrix have much effect on the mechanical properties.
基金Project(2006CB606505) supported by the National Basic Research Development Program of ChinaProject(50333050) supported by the National Natural Science Foundation of China+1 种基金Project(07DJ14002) supported by the Shanghai Fundamental Theory ProgramProject(20020255010) supported by the Specialized Research Fund for the Doctoral Program of Higher Education
文摘Dynamic viscoelastic properties of polyacrylonitrile(PAN)/DMSO/H2O solutions with different H2O contents were studied as a function of temperature.These PAN solutions gradually became gel with decreasing temperature.The sol-gel transition took place at a critical gel temperature,at which the scaling law of G'(ω)～G″(ω)∝ωn held,allowing an accurate determination of the critical gel temperature by means of the frequency independence of the loss tangent.The gel point of PAN solutions increases with increasing H2O content.The scaling exponent n(=0.86) at the gel point is confirmed to be universal for PAN gels,which is independent of temperature,suggesting the similarity of the fractal structure in the critical PAN gels.
文摘To improve the hydrophilicity of polyacrylonitrile-based membranes, sugar moieties were incorporated into acrylonitrile-based copolymers via the radical copolymerization of α-allyl glucoside(AG) with acrylonitrile(AN) with 2,2′-azobis-iso-butyronitrile(AIBN) as the initiator in dimethyl sulphoxide(DMSO). It was found that the yield increased with the increase of the initiator concentration and reaction time, while it decreased with the increase of the monomer molar ratio of AG to AN. Raising the AG proportion in the monomer mixture resulted in the increase of the AG content in the copolymer. M_v of the copolymers decreased with increasing the AG monomer fraction in feed. The copolymers were fabricated into dense membranes and their surface properties were studied by means of the water contact angle measurement and platelet adhesion tests. It was found that the static water contact angle on the membrane decreased significantly from 70° to 33° with the increase of the AG content. The adhesive number of platelets on the membrane surface also decreased significantly with increasing AG content in the copolymers. These results demonstrate that the hydrophilicity and biocompatibility of the acrylonitrile-based copolymer membranes could be improved efficiently by the copolymerization of acrylonitrile with vinyl carbohydrates.
基金Project supported by the National Basic Research Program of China (Grant No.2010CB832902)the Key Program of the National Natural Science Foundation of China (Grant No.10835010)the Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences (Grant No.KJCX2-YW-N35)
文摘Different mass percent polyacrylonitrile （PAN）-polyethylene oxide （PEO） gels were prepared and irradiated by an electron beam （EB） with energy of 1.0 MeV to the dose ranging from 13 kGy to 260 kGy. The gels were analysed by using Fourier transform infrared spectrum, gel fraction and ionic conductivity （IC） measurement. The results show that the gel is crosslinked by EB irradiation, the crosslinking degree rises with the increasing EB irradiation dose （ID） and the mass percents of both PAN and PEO contribute a lot to the crosslinking; in addition, EB irradiation can promote the IC of PAN-PEO gels. There exists an optimum irradiation dose, at which the IC can increase dramatically. The IC changes of the PAN-PEO gels along with ID are divided into three regions： IC rapidly increasing region, IC decreasing region and IC balanced region. The cause of the change can be ascribed to two aspects, gel capturing electron degree and crosslinking degree. By comparing the IC-ID curves of different mass percents of PAN and PEO in gel, we found that PAN plays a more important role for gel IC promotion than PEO, since addition of PAN in gel causes the IC-ID curve sharper, while addition of PEO in gel causes the curve milder.
文摘Polymeric nanofibers are a promising technology to protect the metal surfaces from corrosion.Through the literature search,the use of polyacrylonitrile nanofibres(PANNFs)as a corrosion inhibitor coating for aluminum alloys has not been evaluated.This work includes the development of a new,lightweight,high surface area and efficient coating of PANNFs that produced using electrospinning process to resist the corrosion of aluminum alloys(AA5083)which immersed in 0.6 M NaCl at alkaline medium(pH=12)and acidic medium(pH=1)at a range of temperatures(293–323)K.The PANNFs coating was successfully deposited on AA 5083 specimens,where these samples were considered as a collector electrode in the electrospinning process.The corrosion experiments of the aluminum alloys coated with PANNFs before and after immersion in both corrosive mediums were investigated using cyclic potential polarization(CPP).The results confirmed that the PANNFs coating was able to protect the surface of the aluminum specimens from corrosion,by reducing the corrosion current and increasing the surface polarization resistance,thus reducing the corrosion rate.The protection efficiency was found in the alkaline medium 98.8%while in the acidic medium 83.3%.So,it was in both mediums decreased with the increase in temperature.The shape,distribution and size of the polymeric nanofibers that formed the coating were also examined using field emission scanning electron microscopy(FE-SEM)and the percentages of the structural components of these fibers were detected using the X-ray dispersion spectroscopy(EDS).The surface of aluminum specimens was completely covered by PANNFs.These electrospun nanofibers have worn out and lined up spacing after immersion in the corrosive mediums.The diameters average of PANNFs was found to be about 200 and 150 nm before and after immersion,respectively.
文摘The Lonversion of polyacrylonitrile(PAN)fibre to carbon fibre consists of an oxidative stabili-zation process in which the PAN fibre is heated between 200-300℃ in air to give a thermally co-herent structure.The structural changes of PAN fibres during stabilization have been investigatedusing Fourier Transform Infrared Spectroscopy(FTIR)and Differential Scanning Calorimetry(DSC).An attempt has also been made to follow the conversion of the structure using Ramanspectroscopy as a complementary technique.The FTIR spectra of the fibres subjected to variousdegree of heat treatment show a continuous decrease in nitrile absorption and a simultaneous in-crease in intensity of the C=N and/or C=C bands as the stabilization proceeds.A conversion ra-tio(CR)is defined as the intensity of the C=N and/or C=C bands relative to that of the nitrilegroups.The exotherm present in the DSC experiments was observed to weaken progressively dur-ing the stabilization process.It is confirmed that the original PAN structure is dissipating and thenew ladder polymer is being formed.
