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J M D Tascon - One of the best experts on this subject based on the ideXlab platform.
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nomex derived activated carbon fibers as electrode materials in carbon based supercapacitors
Journal of Power Sources, 2006Co-Authors: K W Leitner, S Villarrodil, F Suarezgarcia, A Martinezalonso, A Lerf, Martin Winter, Jurgen Besenhard, J M D TasconAbstract:Abstract Electrochemical characterization has been carried out for electrodes prepared of several activated carbon fiber samples derived from poly (m-phenylene Isophthalamide) (Nomex) in an aqueous solution. Depending on the burn-off due to activation the BET surface area of the carbons was in the order of 1300–2800 m2 g−1, providing an extensive network of micropores. Their capability as active material for supercapacitors was evaluated by using cyclic voltammetry and impedance spectroscopy. Values for the capacitance of 175 F g−1 in sulfuric acid were obtained. Further on, it was observed that the specific capacitance and the performance of the electrode increase significantly with increasing burn-off degree. We believe that this fact can be attributed to the increase of surface area and porosity with increasing burn-off.
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nanoporous carbon fibres by pyrolysis of nomex polyaramid fibres
Journal of Thermal Analysis and Calorimetry, 2005Co-Authors: J M D TasconAbstract:The development of porosity upon pyrolysis of Nomex®[poly (m-phenylene Isophthalamide)] fibres has been investigated up to a temperature of 1173 K through physical adsorption of N 2 (77 K) and CO 2 (273 K). The carbonisation temperatures were chosen on the basis of thermal analysis studies (TG and DTA). The results of porous texture characterisation were compared with characteristic features in the TG and DTA curves. A temperature of 1073 K was chosen as appropriate for pyrolysis regarding activated carbon fibres preparation.
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Combining thermal analysis with other techniques to monitor the decomposition of poly(m-phenylene Isophthalamide)
Journal of Thermal Analysis and Calorimetry, 2002Co-Authors: S. Villar-rodil, J. I. Paredes, A. Martínez-alonso, J M D TasconAbstract:The pyrolysis behaviour of Nomex, poly( m -phenylene Isophthalamide) fibres under argon has been investigated up to a temperature of 1173 K with different methods to get direct information on the progressive changes taking place in the solid material and its carbon fibre residues. The main stages of the pyrolytic degradation of the fibres were determined by thermal analysis (TG and DTA) and their chemical and morphological evolution through the different steps was subsequently followed by Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) measurements, respectively, on samples treated to various temperatures.
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atomic force microscopy and infrared spectroscopy studies of the thermal degradation of nomex aramid fibers
Chemistry of Materials, 2001Co-Authors: S Villarrodil, A Martinezalonso, J. I. Paredes, J M D TasconAbstract:In the present work, the thermal transformations of Nomex [poly(m-phenylene Isophthalamide)] fibers have been investigated up to a temperature of 1173 K. The main stages of the pyrolytic degradation of the fibers were determined by thermal analysis, and their chemical and morphological evolution through the different steps was subsequently followed by Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) measurements, respectively. The degradation starts with the cleaving of hydrogen bonds at approximately 633 K, which leads to a disordering of the polyaramide chains on the nanometer scale. The next decomposition step takes place between 673 and 873 K with the disruption of the amide bonds, the subsequent breaking of the polyaramide chains into smaller units, and their condensation into large polyaromatic compounds. From 873 K onward, the reaction progresses by the dehydrogenation of the polyaromatic structures and their arrangement into graphite-like assemblies, resulting in th...
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effect of some precursor characteristics on the porous texture of activated carbon fibres prepared from nomex aramid fibres
Microporous and Mesoporous Materials, 2000Co-Authors: M Blanco C Lopez, S Villarrodil, A Martinezalonso, J M D TasconAbstract:Abstract The influence of some characteristics of Nomex [poly( m -phenylene Isophthalamide)] fibres on the porous texture of activated carbon fibres (ACFs) prepared from them by pyrolysis and CO 2 activation has been comparatively analysed. The features studied were the degree of crystallinity and the presence of dyeing additives on the precursor. The obtained ACFs were characterised by N 2 (77 K) and CO 2 (273 K) adsorption, and X-ray diffraction. The results show that the texture developed is mainly related to the degree of burn-off (BO) achieved. Crystallinity differences or the presence of carbon black dye in the precursor brought about little differences in porous texture, the main ones appearing at low and high BOs.
Changwei Zhao - One of the best experts on this subject based on the ideXlab platform.
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preparation characterization and performance of poly m phenylene Isophthalamide organically modified montmorillonite nanocomposite membranes in removal of perfluorooctane sulfonate
Journal of Environmental Sciences-china, 2016Co-Authors: Changwei ZhaoAbstract:Nanocomposite membranes containing poly(m-phenylene Isophthalamide) (PMIA) and organically modified montmorillonite (OMMT) were prepared by a combination of solution dispersion and wet-phase inversion methods, and the effects of OMMT addition on the properties and performance of fabricated nanofiltration membranes were investigated. The membranes were characterized by contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis, and zeta potential. The performance of the membranes was elucidated by the removal of perfluorooctane sulfonate (PFOS) at neutral pH. Increasing OMMT concentration improved the thermal stability and hydrophilicity of the membranes. The permeation and rejection of PFOS were significantly improved. The performance of fabricated nanofiltration membranes in removal of PFOS varied depending on the solute and membrane properties as well as solution conditions. Finally, a comparison between fabricated membranes and a commercial NF membrane (ESNA1-K1, Hydecanme) proved that the OMMT addition is a convenient procedure for producing nanocomposite membranes with superior properties and performance.
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preparation characterization and performance of poly m phenylene Isophthalamide organically modified montmorillonite nanocomposite membranes in removal of perfluorooctane sulfonate
Journal of Environmental Sciences-china, 2016Co-Authors: Changwei ZhaoAbstract:Nanocomposite membranes containing poly(m-phenylene Isophthalamide) (PMIA) and organically modified montmorillonite (OMMT) were prepared by a combination of solution dispersion and wet-phase inversion methods, and the effects of OMMT addition on the properties and performance of fabricated nanofiltration membranes were investigated. The membranes were characterized by contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis, and zeta potential. The performance of the membranes was elucidated by the removal of perfluorooctane sulfonate (PFOS) at neutral pH. Increasing OMMT concentration improved the thermal stability and hydrophilicity of the membranes. The permeation and rejection of PFOS were significantly improved. The performance of fabricated nanofiltration membranes in removal of PFOS varied depending on the solute and membrane properties as well as solution conditions. Finally, a comparison between fabricated membranes and a commercial NF membrane (ESNA1-K1, Hydecanme) proved that the OMMT addition is a convenient procedure for producing nanocomposite membranes with superior properties and performance.
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fabrication of asymmetric poly m phenylene Isophthalamide nanofiltration membrane for chromium vi removal
Journal of Environmental Sciences-china, 2010Co-Authors: Changwei Zhao, Songshan Du, Zhaokun Luan, Jun WangAbstract:The feasibility of employing nanofiltration for the removal of chromium(VI) from wastewater was investigated. Poly (m-phenylene Isophthalamide) (PMIA) was used to fabricate asymmetric nanofiltration membrane through the phase-inversion technique. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the obtained membrane, and the both confirmed a much smoother surface which could reduce membrane fouling. The PMIA membrane showed different rejections to electrolytes in a sequence of Na(2)SO(4) > MgSO(4) > NaCl > MgCl(2), which was similar to the sequence of the negatively charged nanofiltration membranes. Separation experiments on chromium(VI) solution were conducted at various operating conditions, such as feed concentration, applied pressure and pH. It is concluded that chromium(VI) could be effectively removed from chromium-containing wastewater by the PMIA nanofiltration membranes while maintaining their pollution resistance under alkaline condition.
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fabrication of asymmetric poly m phenylene Isophthalamide nanofiltration membrane for chromium vi removal
Journal of Environmental Sciences-china, 2010Co-Authors: Changwei Zhao, Songshan Du, Zhaokun LuanAbstract:The feasibility of employing nanofiltration for the removal of chromium(VI) from wastewater was investigated. Poly (m-phenylene Isophthalamide) (PMIA) was used to fabricate asymmetric nanofiltration membrane through the phase-inversion technique. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize the obtained membrane, and the both confirmed a much smoother surface which could reduce membrane fouling. The PMIA membrane showed different rejections to electrolytes in a sequence of Na(2)SO(4) > MgSO(4) > NaCl > MgCl(2), which was similar to the sequence of the negatively charged nanofiltration membranes. Separation experiments on chromium(VI) solution were conducted at various operating conditions, such as feed concentration, applied pressure and pH. It is concluded that chromium(VI) could be effectively removed from chromium-containing wastewater by the PMIA nanofiltration membranes while maintaining their pollution resistance under alkaline condition.
A Martinezalonso - One of the best experts on this subject based on the ideXlab platform.
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nomex derived activated carbon fibers as electrode materials in carbon based supercapacitors
Journal of Power Sources, 2006Co-Authors: K W Leitner, S Villarrodil, F Suarezgarcia, A Martinezalonso, A Lerf, Martin Winter, Jurgen Besenhard, J M D TasconAbstract:Abstract Electrochemical characterization has been carried out for electrodes prepared of several activated carbon fiber samples derived from poly (m-phenylene Isophthalamide) (Nomex) in an aqueous solution. Depending on the burn-off due to activation the BET surface area of the carbons was in the order of 1300–2800 m2 g−1, providing an extensive network of micropores. Their capability as active material for supercapacitors was evaluated by using cyclic voltammetry and impedance spectroscopy. Values for the capacitance of 175 F g−1 in sulfuric acid were obtained. Further on, it was observed that the specific capacitance and the performance of the electrode increase significantly with increasing burn-off degree. We believe that this fact can be attributed to the increase of surface area and porosity with increasing burn-off.
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effect of phosphoric acid on chemical transformations during nomex pyrolysis
Chemistry of Materials, 2004Co-Authors: F Suarezgarcia, S Villarrodil, C Blanco, A Martinezalonso, Juan M.d. TascónAbstract:The thermal degradation of Nomex [poly(m-phenylene Isophthalamide)] impregnated with phosphoric acid has been investigated by the analysis of the corresponding pyrolysis products, which were fractionated into gases, liquids, and char. Gas chromatography (GC) and/or gas chromatography/mass spectrometry (GC/MS) were used to study the volatiles evolved whereas the solid residue was examined by elemental analysis and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). For the sake of comparison, a parallel study of unimpregnated Nomex was carried out in the same conditions. The main product of unimpregnated Nomex degradation in the conditions of this work was found to be m-benzenediamine, which is the result of a heterolytic process. Aromatic nitriles are also produced through homolytic reactions. Most of the products of impregnated Nomex degradation were also detected with its unimpregnated counterpart, except for isophthalic acid, carbon monoxide, and elemental phosphorus. Aromatic nitrile...
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beneficial effects of phosphoric acid as an additive in the preparation of activated carbon fibers from nomex aramid fibers by physical activation
Fuel Processing Technology, 2002Co-Authors: F Suarezgarcia, A Martinezalonso, Juan M.d. TascónAbstract:Activated carbon fibers (ACFs) were prepared by CO 2 activation of chars obtained by pyrolyzing Nomex [poly (m-phenylene Isophthalamide)], either alone or pre-impregnated with phosphoric acid (impregnation ratio of 7 wt.% H 3 PO 4 ). The resulting materials were characterized by elemental analysis, X-ray diffraction, SEM-EDX, thermogravimetry and N 2 (77 K) and CO 2 (273 K) adsorption. Nomex impregnation with phosphoric acid produced an increase in the char yield in pyrolysis (64.1 vs. 53 wt.% without impregnation) and enhanced the reactivity during activation by an almost sevenfold factor. ACFs with BET surface areas as high as 1300 m 2 g -1 at burn-off degrees of the order of 40% are obtained from both nonimpregnated and impregnated Nomex.
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atomic force microscopy and infrared spectroscopy studies of the thermal degradation of nomex aramid fibers
Chemistry of Materials, 2001Co-Authors: S Villarrodil, A Martinezalonso, J. I. Paredes, J M D TasconAbstract:In the present work, the thermal transformations of Nomex [poly(m-phenylene Isophthalamide)] fibers have been investigated up to a temperature of 1173 K. The main stages of the pyrolytic degradation of the fibers were determined by thermal analysis, and their chemical and morphological evolution through the different steps was subsequently followed by Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) measurements, respectively. The degradation starts with the cleaving of hydrogen bonds at approximately 633 K, which leads to a disordering of the polyaramide chains on the nanometer scale. The next decomposition step takes place between 673 and 873 K with the disruption of the amide bonds, the subsequent breaking of the polyaramide chains into smaller units, and their condensation into large polyaromatic compounds. From 873 K onward, the reaction progresses by the dehydrogenation of the polyaromatic structures and their arrangement into graphite-like assemblies, resulting in th...
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effect of some precursor characteristics on the porous texture of activated carbon fibres prepared from nomex aramid fibres
Microporous and Mesoporous Materials, 2000Co-Authors: M Blanco C Lopez, S Villarrodil, A Martinezalonso, J M D TasconAbstract:Abstract The influence of some characteristics of Nomex [poly( m -phenylene Isophthalamide)] fibres on the porous texture of activated carbon fibres (ACFs) prepared from them by pyrolysis and CO 2 activation has been comparatively analysed. The features studied were the degree of crystallinity and the presence of dyeing additives on the precursor. The obtained ACFs were characterised by N 2 (77 K) and CO 2 (273 K) adsorption, and X-ray diffraction. The results show that the texture developed is mainly related to the degree of burn-off (BO) achieved. Crystallinity differences or the presence of carbon black dye in the precursor brought about little differences in porous texture, the main ones appearing at low and high BOs.
S Villarrodil - One of the best experts on this subject based on the ideXlab platform.
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nomex derived activated carbon fibers as electrode materials in carbon based supercapacitors
Journal of Power Sources, 2006Co-Authors: K W Leitner, S Villarrodil, F Suarezgarcia, A Martinezalonso, A Lerf, Martin Winter, Jurgen Besenhard, J M D TasconAbstract:Abstract Electrochemical characterization has been carried out for electrodes prepared of several activated carbon fiber samples derived from poly (m-phenylene Isophthalamide) (Nomex) in an aqueous solution. Depending on the burn-off due to activation the BET surface area of the carbons was in the order of 1300–2800 m2 g−1, providing an extensive network of micropores. Their capability as active material for supercapacitors was evaluated by using cyclic voltammetry and impedance spectroscopy. Values for the capacitance of 175 F g−1 in sulfuric acid were obtained. Further on, it was observed that the specific capacitance and the performance of the electrode increase significantly with increasing burn-off degree. We believe that this fact can be attributed to the increase of surface area and porosity with increasing burn-off.
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effect of phosphoric acid on chemical transformations during nomex pyrolysis
Chemistry of Materials, 2004Co-Authors: F Suarezgarcia, S Villarrodil, C Blanco, A Martinezalonso, Juan M.d. TascónAbstract:The thermal degradation of Nomex [poly(m-phenylene Isophthalamide)] impregnated with phosphoric acid has been investigated by the analysis of the corresponding pyrolysis products, which were fractionated into gases, liquids, and char. Gas chromatography (GC) and/or gas chromatography/mass spectrometry (GC/MS) were used to study the volatiles evolved whereas the solid residue was examined by elemental analysis and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). For the sake of comparison, a parallel study of unimpregnated Nomex was carried out in the same conditions. The main product of unimpregnated Nomex degradation in the conditions of this work was found to be m-benzenediamine, which is the result of a heterolytic process. Aromatic nitriles are also produced through homolytic reactions. Most of the products of impregnated Nomex degradation were also detected with its unimpregnated counterpart, except for isophthalic acid, carbon monoxide, and elemental phosphorus. Aromatic nitrile...
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atomic force microscopy and infrared spectroscopy studies of the thermal degradation of nomex aramid fibers
Chemistry of Materials, 2001Co-Authors: S Villarrodil, A Martinezalonso, J. I. Paredes, J M D TasconAbstract:In the present work, the thermal transformations of Nomex [poly(m-phenylene Isophthalamide)] fibers have been investigated up to a temperature of 1173 K. The main stages of the pyrolytic degradation of the fibers were determined by thermal analysis, and their chemical and morphological evolution through the different steps was subsequently followed by Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) measurements, respectively. The degradation starts with the cleaving of hydrogen bonds at approximately 633 K, which leads to a disordering of the polyaramide chains on the nanometer scale. The next decomposition step takes place between 673 and 873 K with the disruption of the amide bonds, the subsequent breaking of the polyaramide chains into smaller units, and their condensation into large polyaromatic compounds. From 873 K onward, the reaction progresses by the dehydrogenation of the polyaromatic structures and their arrangement into graphite-like assemblies, resulting in th...
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effect of some precursor characteristics on the porous texture of activated carbon fibres prepared from nomex aramid fibres
Microporous and Mesoporous Materials, 2000Co-Authors: M Blanco C Lopez, S Villarrodil, A Martinezalonso, J M D TasconAbstract:Abstract The influence of some characteristics of Nomex [poly( m -phenylene Isophthalamide)] fibres on the porous texture of activated carbon fibres (ACFs) prepared from them by pyrolysis and CO 2 activation has been comparatively analysed. The features studied were the degree of crystallinity and the presence of dyeing additives on the precursor. The obtained ACFs were characterised by N 2 (77 K) and CO 2 (273 K) adsorption, and X-ray diffraction. The results show that the texture developed is mainly related to the degree of burn-off (BO) achieved. Crystallinity differences or the presence of carbon black dye in the precursor brought about little differences in porous texture, the main ones appearing at low and high BOs.
D Mohan - One of the best experts on this subject based on the ideXlab platform.
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permeation characteristics of tailored poly m phenylene Isophthalamide ultrafiltration membranes and probing its efficacy on bovine serum albumin separation
Polymer Testing, 2018Co-Authors: J Pramila, J Beril S Melbiah, Dipak Rana, Nagendra N Gandhi, A Nagendran, D MohanAbstract:Abstract Poly (m-phenylene Isophthalamide) (PMIA) ultrafiltration (UF) membranes has been prepared using lithium chloride (LiCl) and poly (ethylene glycol) of average molecular weight 600 Da (PEG 600) as additives by phase inversion technique. Membranes were characterized by FTIR, TGA, DTG and UTM. Surface characteristics are probed by SEM, AFM and water contact Angle. It was evidenced from SEM analysis that all membranes have macrovoids in its structure and hence possess high water permeability. Accordingly, all membranes were highly hydrophilic in nature which can be predicted from water wettability and work of adhesion measurement using contact angle. Further, membranes were subjected for protein rejection study using bovine serum albumin (BSA) as a model foulant and its fouling ability was analyzed. It has been found that the 10 wt.% PMIA membrane with 2 wt% of PEG 600 and 4 wt.% of LiCl has high water permeability and better reversible and irreversible antifouling capability than any other prepared membranes. Flux recovery ratio (FRR) of 91% was obtained for the 10 wt.% PMIA also confirmed it is one of the promising UF membrane materials.
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poly Isophthalamide based graft copolymer for the modification of cellulose acetate ultrafiltration membranes and a fouling study by afm imaging
Journal of Membrane Science, 2014Co-Authors: A Jayalakshmi, Sahadevan Rajesh, I C Kim, S Senthilkumar, D Mohan, Youngnam KwonAbstract:Abstract Poly(Isophthalamide) based copolymer, poly(Isophthalamide)-graft-methacrylamide (PIPA-g-MAA) has been prepared and used to modify the surface and fouling liable properties of the cellulose acetate (CA) membranes. Grafting facilitated the solubility of PIPA in common aprotic solvents and made it available as a potential membrane material for the modification of CA membrane. Compatibility between CA and PIPA-g-MAA in blend membranes was confirmed by a single glass transition temperature, and improved hydrophilicity of the membranes was illustrated by the lower contact angle values. The thermal and mechanical stability of the CA membrane was also improved by the blending with PIPA-g-MAA. The separation efficiency of various commercial proteins by these CA/PIPA-g-MAA blend membranes was studied and found to have improved significantly. The fouling propensity of the membranes was studied using BSA as a model foulant and the resistance arising during different stages of filtration was evaluated using resistance in series model. From the AFM images it could be observed that protein uniformly covers the blend membrane surfaces and non-uniform protein clusters are formed in the CA membranes due to preferential adsorption at specific sites. The irreversible fouling resistance (Rir) could be greatly reduced by the incorporation of the synthesized PIPA-g-MAA in the CA matrix.
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preparation of poly Isophthalamide graft methacrylamide and its utilization in the modification of cellulose acetate ultrafiltration membranes
Journal of Industrial and Engineering Chemistry, 2014Co-Authors: A Jayalakshmi, Sahadevan Rajesh, S Senthilkumar, H Hari S Sankar, D MohanAbstract:Abstract Methacrylamide was grafted on to poly (Isophthalamide) (PIPA-g-MAA) to improve its solubility and hydrophilicity. Then, PIPA-g-MAA incorporated high performance cellulose acetate ultrafiltration (CA) membranes were prepared by phase inversion technique and physical properties of the membranes were studied by various analytical methods. The efficiency of these membranes in the removal of arsenic from aqueous stream was studied and an effort has been taken to correlate the separation efficiency with morphology. Overall results suggest that membrane hydrophilicity, structure and performance were improved significantly by the addition of PIPA-g-MAA. Thus PIPA-g-MAA can be considered as an effective modification agent for CA membranes.
