Activated Carbon Hollow Fibers Research Articles

Facile fabrication of N/O co-doped activated carbon hollow fibers for hydrogen storage at atmospheric pressure

Facile fabrication of N/O co-doped activated carbon hollow fibers for hydrogen storage at atmospheric pressure

Preparation of N, P self-doped activated carbon hollow fibers derived from liquefied wood

The heteroatom self-doped activated carbon hollow fibers from liquefied wood (ACHFs) were prepared by melt spinning, half-curing, carbonization and activation using steam. The results showed that the ACHFs with N and P doping exhibited high specific surface area (1896.6–2040.8 m2g−1) and total pore volume (1.02–1.058 cm3g−1). It was also found that the mechanisms of P from catalyst and N from curing agent were different in the formation of pore structure of ACHFs. When applied to supercapacitor, the ACHF-N10P16 can deliver a high specific capacitance of 151 F g−1 at current density of 1 A g−1 in 6 M KOH electrolyte. In addition, ACHFs displayed the synergistic advantages of pseudo-capacitance and double-layer capacitance because of N and P doping. As a result, the ACHFs with adjustable heteroatom doping have a broad application prospect in electrochemical energy storage.

In situ hydrothermal synthesis of MnO2 nanowires/wood derived activated carbon hollow fibers composite and its application in supercapacitor

In situ hydrothermal synthesis of MnO2 nanowires/wood derived activated carbon hollow fibers composite and its application in supercapacitor

Preparation and adsorption of CO2 and H2 by activated carbon hollow fibers from rubber wood (Hevea brasiliensis)

A series of activated carbon hollow fibers doped with charcoal powder (WC-ACHFs) were prepared from wood waste with great potential for application in the gas adsorption of CO2 and H2. The hydrogen storage of WC-ACHF-1.0% increased approximately 10.5% more than that of activated carbon hollow fibers (ACHF), and the highest hydrogen uptake reached 4.51 wt% at 77 K and 100 bar. Regarding the CO2 adsorption, the highest adsorption amount reached 7.13 mmol g-1 and the mass content was 31.35 at 273 K, which was 49.8% higher than the sample without doping. In addition, the multiple heteroatoms (N, P) from wood waste liquefaction had a synergistic effect on the gas adsorption properties of WC-ACHFs. These results showed that a facile method was promising for the preparation of wood-derived activated carbon hollow fibers from forestry and agricultural residues in the application of gas adsorption.

Improvement of electrochemical properties of activated carbon hollow fibers from liquefied wood by charcoal power

Abstract A series of activated carbon hollow fibers doped with charcoal powder (WC-ACHFs) were prepared from wood waste by liquefaction, melt spinning and steam activation methods. When evaluated as electrodes, activated carbon hollow fibers doped with charcoal powder exhibited an outstanding gravimetric specific capacitance of 481 F g−1 at 0.5 A g−1 and cyclic stability with 98.8% capacitance retention over 2000 cycles. In addition, the multiple heteroatoms-doping of N and P from wood waste liquefaction have synergistic effect on electrochemical properties of WC-ACHFs, which is due to its combined merits of pseudocapacitance for sufficient charge storage and the good wettability for efficient ion diffusion. These results display that a facile method is promising for the preparation of wood-derived activated carbon hollow fibers from forestry and agricultural residues in the application of electrochemical energy storage.

A facile approach to prepare biomass-derived activated carbon hollow fibers from wood waste as high-performance supercapacitor electrodes

In this paper, several activated carbon hollow fibers (ACHF) with high surface area of ~ 1873 m2 g−1 were prepared from wood waste by liquefaction, half-curing and one-step activation methods. Scanning electron microscopy, Nitrogen gas adsorption–desorption and X-ray photoelectron spectroscopy have been used to characterize the morphology, the structure and the composition of ACHF. Results show added wood charcoal had a noticeable influence on the pore structure and electrochemical performance of ACHF. Electrochemical investigation measurements show that ACHF exhibit an outstanding specific capacitance (295 F g−1 at 0.5 A g−1), excellent rate performance (73.8% capacitance retention at 20 A g−1), high energy density (7.8 W h kg−1) and high capacitance retention of 99.5% over 10,000 charge–discharge cycles. Moreover, the multiple heteroatoms (N, P) from wood liquefaction have a synergistic effect on electrochemical properties of ACHF. These results indicate the present method is promising for the preparation of biomass-derived activated carbon hollow fibers from agricultural and forestry waste in the application of supercapacitors.

Effect of ZnCl2 impregnation concentration on the microstructure and electrical performance of ramie-based activated carbon hollow fiber

Activated carbon hollow fibers (ACHFs) with high surface area were prepared from natural ramie fibers (RFs) by one-step activation under different ZnCl2 impregnation concentrations. The results showed that the morphology and pore structure development of ACHFs depend greatly on ZnCl2 concentration because ZnCl2 not only can swell and dissolve cellulose but also can serve as skeleton of newborn pores. It obtained granular activated carbons (ACs) instead of ACHFs when ZnCl2 concentration was over a suitable range. As supercapacitor electrode, the ACHFs possessed the maximum capacity of 287 F g−1 and showed excellent stability with more than 93 % efficiency after 1000 cycles. Besides, ACHFs showed higher electrochemical performance than granular ACs even if their microstructure was similar, indicating the morphology of material is also important to the electrochemical properties. Therefore, supercapacitors using ramie-based ACHFs as electrodes possess high comprehensive properties to serve for the need of backup energy storage and high pulse power applications.

Preparation of activated carbon hollow fibers from ramie at low temperature for electric double-layer capacitor applications

Activated carbon hollow fibers (ACHFs) with high surface area were prepared from inexpensive, renewable ramie fibers (RFs) by a single-step activation method under lower temperature than that of other reports. The effects of activation conditions on the pore structure and turbostratic structure of ACHFs were investigated systematically. The results show that ACHFs surface area decreased but micropore volume and conductivity increased as the increase of activation temperature and activation time. The electrochemical measurements of supercapacitors fabricated from these ACHFs electrodes reveal that the electrochemical properties improved with the enhancing of activation degree. However, too high activation temperature can make the ion diffusion resistance increase. It suggests that pore structure and conductivity are as important as surface area to decide the electrochemical performances of ACHFs electrode materials. A maximum capacity of 287 F g(-1) at 50 mA g(-1) was obtained for the ACHFs electrode prepared under suitable conditions.

A methodology for the morphological and physicochemical characterisation of asymmetric carbon hollow fiber membranes

Carbon and activated carbon hollow fiber membranes were prepared from an asymmetric co-polyimide precursor through the application of common pyrolytic carbonization procedures followed by carbon dioxide activation. A complete analytical methodology, consisting of a combination of advanced static and dynamic techniques, is proposed as a tool to elucidate the asymmetric pore structure of the developed carbon membranes. More specific, the carbon hollow fiber morphology was investigated by scanning electron microscopy. The mean micropore size of the existing separating layers was defined by surface excess adsorption of the probe molecules H 2, CO 2, N 2 and CH 4. The micropore size distribution was derived by means of the Grand Canonical Monte Carlo simulation method, using the experimental data of either the H 2 77 K or both H 2 and CO 2 adsorption isotherms. In addition, single phase and relative permeability experiments revealed the coexistence of a small population of mesopores on the pore structure of the dense separating layers. Overall, the proposed methodology has been proved sufficient to distinguish the simultaneous occurrence of three separating layers in each of the developed membranes and discriminate between their different pore structures.

Structure and properties of PAN‐based activated carbon hollow fibers: Effect of ammonium dibasic phosphate pretreatment

AbstractPolyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate aqueous solution, then further oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of pretreatment concentration of ammonium dibasic phosphate aqueous solution on the microstructure, specific surface, pore size distribution, and adsorption properties of PAN‐based activated carbon hollow fibers (PAN‐ACHF) were studied in this work. After the activation process, the Brunaner‐Emmett‐Teller (BET) surface area of the PAN‐ACHF and surface area of mesopores in the PAN‐ACHF increases and reaches 513 m2g−1 and 66 m2g−1 respectively when the concentration of ammonium dibasic phosphate aqueous solution is 4% (wt %). The adsorptions to creatinine are much high, reach more than 90% over all the concentration of ammonium dibasic phosphate aqueous solution. The adsorptions to VB12 of PAN‐ACHF reach 86% when the concentration of ammonium dibasic phosphate aqueous solution is 4% (wt %). The dominant pore sizes of mesopores in PAN‐ACHF range from 2 to 5 nm. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Adsorption characteristics of activated carbon hollow fibers

Carbon hollow fibers were prepared with regenerated cellulose or polysulfone hollow fibers by chemical activation using sodium phosphate dibasic followed by the carbonization process. The activation process increases the adsorption properties of fibers which is more prominent for active carbone fibers obtained from the cellulose precursor. Chemical activation with sodium phosphate dibasic produces an active carbon material with both mesopores and micropores.

Effects of oxidation time on the structure and properties of polyacrylonitrile‐based activated carbon hollow fiber

AbstractPolyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate, then further oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of oxidation time of PAN hollow fiber precursor on the microstructure, specific surface, pore size distribution, and adsorption properties of PAN‐based activated carbon hollow fiber (PAN‐ACHF) were studied in this work. Both of specific surface area and adsorption ratio to VB12 reach maximums when PAN hollow fibers are oxidized for 5 h in air. The adsorption ratios for creatinine are all higher than 90% over all oxidation time. After 5 h of oxidation, the number of pores on the surface obviously increases, and the pore size is uniform. After 7 h of oxidation, the number of macropores in PAN‐ACHF increases. The dominant pore sizes of mesopores in PAN‐ACHF range from 2 to 5 nm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Effects of ammonium dibasic phosphate pretreatment time on the structure and properties of PAN‐based activated carbon hollow fibers

AbstractPolyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate aqueous solution, then further oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of pretreatment time of PAN hollow fibers in ammonium dibasic phosphate aqueous solution on the microstructure, specific surface, pore‐size distribution, and adsorption properties of PAN‐based activated carbon hollow fibers (PAN‐ACHF) were studied in this work. After the activation process, the Brunaner–Emmett–Teller (BET) surface area of the PAN‐ACHF and surface area of mesopores in the PAN‐ACHF increases and reaches 513 m2 g−1 and 66 m2 g−1 respectively, when the dipping time of PAN hollow fibers in ammonium dibasic phosphate aqueous solution is 30 min. The adsorptions to creatinine and VB12 of PAN‐ACHF are much high, reach 95% and 86% respectively, when dipping time is 30 min. The dominant pore sizes of mesopores in PAN‐ACHF range from 2 nm to 5 nm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2448–2453, 2006

Effects of activation temperature on the properties and structure of PAN‐based activated carbon hollow fiber

AbstractPolyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate, then further oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of activation temperature of a precursor fiber on the microstructure, specific surface, pore‐size distribution, and adsorption properties of PAN‐based activated carbon hollow fibers (PAN‐ACHF) were studied in this work. After the activation process, the BET surface area of the PAN‐ACHF and surface area of mesopores in the PAN‐ACHF increased very remarkably and reached 1422 m2 g−1 and 1234 m2 g−1, respectively, when activation temperature is 1000°C. The adsorptions to creatinine and VB12 of PAN‐ACHF were much high and reached 99 and 84% respectively. In PAN‐ACHF which went through the activation at 700°C and 800°C, the micropore filling mainly occurred at low relative pressures, multimolecular layer adsorption occurred with the increasing of relative pressure, and the filling and emptying of the mesopores by capillary condensation occurred at high relative pressures. But in PAN‐ACHF which went through the activation at 900°C, a mass of mesopores resulted in the large pore filling by capillary condensation. The dominant pore sizes of mesopores in PAN‐ACHF are from 2 nm to 5 nm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3778–3783, 2006

Effects of activation time on the properties and structure of polyacrylonitrile‐based activated carbon hollow fiber

AbstractPolyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate, then further oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of activation time of a precursor fiber on the microstructure, specific surface area, pore‐size distribution, and adsorption properties of PAN‐based activated carbon hollow fibers (PAN‐ACHF) were studied in this work. The BET surface area of PAN‐ACHF and surface area of mesopores gradually increase with activation time extending, and reach the maximum values, 780 and 180 m2 g−1, respectively, when fibers are activated at 800°C for 100 min. The adsorption ratio to creatinine changes little with activation time extending and all values over all activation time are above 90%. The adsorption ratio to VB12 gradually increases with activation time extending before 60 min, and then becomes relatively constant from 60 to 100 min. The number of pores on the surface of PAN‐ACHF increases with activation time extending. The amount of mesopores in PAN‐ACHF made of fibers activated for different time increases with activation time extending and the dominant pore sizes of mesopores in PAN‐ACHF range from 2 to 5 nm. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2565–2569, 2006

Effects of the oxidation temperature on the structure and properties of polyacrylonitrile‐based activated carbon hollow fiber

AbstractPolyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate, oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of the oxidation temperature of the PAN hollow fiber precursor on the microstructure, specific surface, pore size distribution, and adsorption properties of PAN‐based activated carbon hollow fiber (PAN‐ACHF) were studied. When PAN hollow fibers were oxidized at 270°C, because of drastic oxidation, chain scission occurred, and the number of pores within and on the surface of the resultant PAN‐ACHF increased, but the pores were just in the thinner region of the skin of PAN‐ACHF. The surface area of PAN‐ACHF reached a maximum when the oxidation temperature was 270°C. The adsorption ratios to creatinine were all higher than 90% at all oxidation temperatures, and the adsorption ratio to VB12 reached a maximum (97%) at 230°C. The dominant pore sizes of the mesopores in PAN‐ACHF ranged from 2 to 5 nm. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 203–207, 2005

The effects of carbonization temperature on the properties and structure of PAN‐based activated carbon hollow fiber

AbstractPolyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate and then further oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of carbonization temperature of PAN hollow fiber precursor on the microstructure, specific surface, pore‐size distribution, and adsorption properties of PAN‐based carbon hollow fiber (PAN‐CHF) and PAN‐based activated carbon hollow fibers (PAN‐ACHF) were studied in this work. After the activation process, the surface area of the PAN‐ACHF increased very remarkably, reaching 900 m2 g−1 when carbonization is 1000°C, and the adsorption ratios to creatinine and VB12 of ACHF were much higher than those of CHF, especially to VB12. The different adsorption ratios to two adsorbates including creatinine and VB12 reflect the number of micropores and mesopores in PAN‐ACHF. The dominant pore sizes of mesopores in PAN‐ACHF are from 2 to 5 nm. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2155–2160, 2005

Comparison about the structure and properties of PAN‐based activated carbon hollow fibers pretreated with different compounds containing phosphorus

AbstractPolyacrylonitrile (PAN) hollow fibers were pretreated with five different compounds containing phosphorus, including ammonium dibasic phosphate, ammonium dihydrogen phosphate, triammonium phosphate, phosphoric acid, and metaphosphoric acid, and then further oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of different compounds containing phosphorus as pretreating agents on the properties and structure of the resultant oxidized hollow fibers, carbon hollow fibers, and activated carbon hollow fibers are discussed. Comparing the Brunaner‐Emmett‐Teller (BET) surface area of PAN‐activated carbon hollow fibers (ACHF) pretreated with five different compounds, ammonium dibasic phosphate > triammonium phosphate > ammonium dihydrogen phosphate > phosphoric acid > metaphosphoric acid, and the surface area of mesopores in PAN‐ACHF pretreated with ammonium dibasic phosphate reaches maximum, 174 m2 g−1. The adsorption ratio to mesomolecule adsorbate, VB12, of PAN‐ACHF pretreated with ammonium dibasic phosphate also reaches maximum, 97.7 wt %. Moreover, the dominant pore sizes of PAN‐ACHF range from 2 to 5 nm in diameter. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 294–300, 2005

The effects of carbonization time on the properties and structure of PAN-based activated carbon hollow fiber

Polyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate, then further oxidized in air, carbonized in nitrogen and activated with carbon dioxide. The effects of carbonization time of PAN hollow fiber precursor on the microstructure, specific surface, pore-size distribution and adsorption properties of PAN-based carbon hollow fiber (PAN-CHF) and PAN-based activated carbon hollow fiber (PAN-ACHF) were studied in this work. After the activation process, the surface area of the PAN-ACHF increased very remarkably, reaches 506 m2⋅g− 1, when fibers are carbonized at 900∘C for 70 min and activated at 800∘C for 40 min. The different adsorption ratios to two adsorbates including creatinine and VB12 reflect the number of micropores and mesopores in PAN-ACHF. The dominant pore sizes of mesopores in PAN-ACHF range from 2 to 5 nm

Adsorption properties of polyacrylonitrile-based activated carbon hollow fiber

In this work, polyacrylonitrile (PAN) hollow fibers are pretreated with ammonium dibasic phosphate and then further oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The adsorption properties of the resultant activated carbon hollow fibers (ACHF) prepared in different conditions were studied. The results show that the adsorption properties of ACHF change regularly with preparing conditions of ACHF. The different adsorption ratios to three adsorbates reflect the number of micropores and mesopores in PAN-based ACHF. Pretreatment with phosphate can increase the number of mesopores. Proper oxidation temperature and time can increase the number of micropores and mesopores. When carbonization temperature is more than 900°C and carbonization time ranges from 50 to 90 min, the number of micropores and mesopores, especially mesopores, greatly increases. Compared with other treatments, activation treatment greatly increases the number of micropores and mesopores, and the dominant pore sizes of mesopores in PAN-based ACHF are from 2 to 10 nm. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 602–607, 2004