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1

Preparation and characterization of mesoporous activated carbon from waste tires  

Microsoft Academic Search

Activated carbons were produced from waste tires and their characteristics were investigated. Rubber separated from waste tires was first carbonized at 500°C in N2 atmosphere. Next, the obtained chars were activated with steam at 850°C. As a result, fairly mesoporous activated carbons with mesopore volumes and BET surface areas up to 1.09 cm3\\/g and 737 m2\\/g, respectively, were obtained. To

P Ariyadejwanich; W Tanthapanichakoon; K Nakagawa; S. R Mukai; H Tamon

2003-01-01

2

Hierarchical activated mesoporous phenolic-resin-based carbons for supercapacitors.  

PubMed

A series of hierarchical activated mesoporous carbons (AMCs) were prepared by the activation of highly ordered, body-centered cubic mesoporous phenolic-resin-based carbon with KOH. The effect of the KOH/carbon-weight ratio on the textural properties and capacitive performance of the AMCs was investigated in detail. An AMC prepared with a KOH/carbon-weight ratio of 6:1 possessed the largest specific surface area (1118?m(2) ?g(-1) ), with retention of the ordered mesoporous structure, and exhibited the highest specific capacitance of 260?F?g(-1) at a current density of 0.1?A?g(-1) in 1?M H2 SO4 aqueous electrolyte. This material also showed excellent rate capability (163?F?g(-1) retained at 20?A?g(-1) ) and good long-term electrochemical stability. This superior capacitive performance could be attributed to a large specific surface area and an optimized micro-mesopore structure, which not only increased the effective specific surface area for charge storage but also provided a favorable pathway for efficient ion transport. PMID:25100552

Wang, Zhao; Zhou, Min; Chen, Hao; Jiang, Jingui; Guan, Shiyou

2014-10-01

3

Preparation of activated mesoporous carbons for electrosorption of ions from aqueous solutions  

SciTech Connect

Mesoporous carbon with a narrow pore size distribution centered at about 9 nm, which was prepared by self assembly of block copolymer and phloroglucinol-formaldehyde resin via the soft-template method, was activated by CO{sub 2} and potassium hydroxide (KOH). The effects of activation conditions, such as the temperature, activation time, and mass ratio of KOH/C, on the textural properties of the resulting activated mesoporous carbons were investigated. Activated mesoporous carbons exhibit high BET specific surface areas (up to {approx} 2000 m{sup 2} g{sup -1}) and large pore volumes (up to {approx} 1.6 cm{sup 3} g{sup -1}), but still maintain a highly mesoporous structure. Heat treatment of mesoporous carbons by CO{sub 2} generally requires a moderate to high extent of activation in order to increase its BET surface area by 2-3 times, while KOH activation needs a much smaller degree of activation than the former to reach an identical surface area, ensuring high yields of activated mesoporous carbons. In addition, KOH activation allows a controllable degree of activation by adjusting the mass ratio of KOH/C (2-8), as evidenced by the fact that surface area and pore volume increase with the mass ratio of KOH/C. The electrosorption properties of activated mesoporous carbons were investigated by cyclic voltammetry in 0.1 M NaCl aqueous solutions. Upon activation, the electrosorption capacitance of activated mesoporous carbons was greatly enhanced.

Dai, Sheng [ORNL; Lee, Jeseung [ORNL; Tsouris, Costas [ORNL; DePaoli, David W [ORNL; Wang, Xiqing [ORNL

2010-01-01

4

Preparation and characteristics of agricultural waste activated carbon by physical activation having micro- and mesopores  

Microsoft Academic Search

Micro–mesoporous activated carbons were prepared from various agricultural wastes by physical activation. Agricultural wastes such as macadamia nut-shell, corncob, bagasse bottom ash, sawdust fly ash and rice husk fly ash, were optimized and processed to obtain the highest surface area. The effects of the amount of volatile matter in char, the activating agent, the activating temperature and kind of raw

Amphol Aworn; Paitip Thiravetyan; Woranan Nakbanpote

2008-01-01

5

Nanoconfinement in activated mesoporous carbon of calcium borohydride for improved reversible hydrogen storage  

NASA Astrophysics Data System (ADS)

Mesoporous carbon frameworks were synthesized using the soft-template method. Ca(BH4)2 was incorporated into activated mesoporous carbon by the incipient wetness method. The activation of mesoporous carbon was necessary to optimize the surface area and pore size. Thermal programmed absorption measurements showed that the confinement of this borohydride into carbon nanoscaffolds improved its reversible capacity (relative to the reactive portion) and performance of hydrogen storage compared to unsupported borohydride. Hydrogen release from the supported hydride started at a temperature as low as 100?°C and the dehydrogenation rate was fast compared to the bulk borohydride. In addition, the hydrogen pressure necessary to regenerate the borohydride from the dehydrogenation products was reduced.

Com?nescu, Cezar; Capurso, Giovanni; Maddalena, Amedeo

2012-09-01

6

Preparation of activated carbons with mesopores by use of organometallics  

SciTech Connect

Activated carbons are commercially produced by steam or CO{sub 2} activation of coal, coconut shell and so on. In general the carbons obtained give pores with a broad range of distribution. The objective of this study was to prepare activated carbons from coal by use of various organometallic compounds. The carbons were evaluated for pore size by nitrogen adsorption experiments.

Yamada, Yoshio; Yoshizawa, Noriko; Furuta, Takeshi [National Institute for Resources and Environment, Tsukuba, Ibaraki (Japan)] [and others

1996-12-31

7

Mesoporous carbon materials  

DOEpatents

The invention is directed to a method for fabricating a mesoporous carbon material, the method comprising subjecting a precursor composition to a curing step followed by a carbonization step, the precursor composition comprising: (i) a templating component comprised of a block copolymer, (ii) a phenolic compound or material, (iii) a crosslinkable aldehyde component, and (iv) at least 0.5 M concentration of a strong acid having a pKa of or less than -2, wherein said carbonization step comprises heating the precursor composition at a carbonizing temperature for sufficient time to convert the precursor composition to a mesoporous carbon material. The invention is also directed to a mesoporous carbon material having an improved thermal stability, preferably produced according to the above method.

Dai, Sheng; Wang, Xiqing

2013-08-20

8

Adsorption and structural properties of soft-templated mesoporous carbons obtained by carbonization at different temperatures and KOH activation  

NASA Astrophysics Data System (ADS)

Two series of phenolic resin-based mesoporous carbons were prepared by soft-templating strategy, which involves the formation of thermosetting carbon precursor by polymerization of phloroglucinol and formaldehyde in hydrophilic mesodomains of a thermally decomposable triblock copolymer used as a soft-template. It was shown that the volumes of mesopores and micropores in the resulting carbons can be tuned by varying carbonization temperature of phenolic resins in the range from 400 to 1000 °C followed by the post-synthesis KOH activation at 700 °C. The highly microporous carbons were obtained by KOH activation of phenolic resins pyrolyzed at lower temperature (˜500 °C), while high temperature KOH activation (˜800 °C) afforded microporous carbons with preserved mesoporosity.

Górka, Joanna; Zawislak, Aleksandra; Choma, Jerzy; Jaroniec, Mietek

2010-06-01

9

New route toward building active ruthenium nanoparticles on ordered mesoporous carbons with extremely high stability.  

PubMed

Creating highly active and stable metal catalysts is a persistent goal in the field of heterogeneous catalysis. However, a real catalyst can rarely achieve both of these qualities simultaneously due to limitations in the design of the active site and support. One method to circumvent this problem is to fabricate firmly attached metal species onto the voids of a mesoporous support formed simultaneously. In this study, we developed a new type of ruthenium catalyst that was firmly confined by ordered mesoporous carbons through the fabrication of a cubic Ia3d chitosan-ruthenium-silica mesophase before pyrolysis and silica removal. This facile method generates fine ruthenium nanoparticles (ca. 1.7?nm) that are homogeneously dispersed on a mesoporous carbonaceous framework. This ruthenium catalyst can be recycled 22 times without any loss of reactivity, showing the highest stability of any metal catalysts; this catalyst displays a high activity (23.3?mol(LA)h(-1)g(metal)(-1)) during the catalytic hydrogenation of levulinic acid (LA) when the metal loading is 6.1?wt%. Even at an ultralow loading (0.3?wt%), this catalyst still outperforms the most active known Ru/C catalyst. This work reveals new possibilities for designing and fabricating highly stable and active metal catalysts by creating metal sites and mesoporous supports simultaneously. PMID:24687047

Yang, Ying; Sun, Chengjun; Ren, Yang; Hao, Shijie; Jiang, Daqiang

2014-01-01

10

New route toward building active ruthenium nanoparticles on ordered mesoporous carbons with extremely high stability  

NASA Astrophysics Data System (ADS)

Creating highly active and stable metal catalysts is a persistent goal in the field of heterogeneous catalysis. However, a real catalyst can rarely achieve both of these qualities simultaneously due to limitations in the design of the active site and support. One method to circumvent this problem is to fabricate firmly attached metal species onto the voids of a mesoporous support formed simultaneously. In this study, we developed a new type of ruthenium catalyst that was firmly confined by ordered mesoporous carbons through the fabrication of a cubic Ia3d chitosan-ruthenium-silica mesophase before pyrolysis and silica removal. This facile method generates fine ruthenium nanoparticles (ca. 1.7 nm) that are homogeneously dispersed on a mesoporous carbonaceous framework. This ruthenium catalyst can be recycled 22 times without any loss of reactivity, showing the highest stability of any metal catalysts; this catalyst displays a high activity (23.3 molLAh-1gmetal-1) during the catalytic hydrogenation of levulinic acid (LA) when the metal loading is 6.1 wt%. Even at an ultralow loading (0.3 wt%), this catalyst still outperforms the most active known Ru/C catalyst. This work reveals new possibilities for designing and fabricating highly stable and active metal catalysts by creating metal sites and mesoporous supports simultaneously.

Yang, Ying; Sun, Chengjun; Ren, Yang; Hao, Shijie; Jiang, Daqiang

2014-04-01

11

Sulfur-Functionalized Mesoporous Carbon  

SciTech Connect

A simple, direct synthesis of mesoporous carbons containing heteroaromatic functionality is described. Superior performance of these mesoporous heterocarbons as heavy metal sorbent material is demonstrated. These materials are shown to be stable towards elevated temperatures and extreme pHs.

Shin, Yongsoon; Fryxell, Glen E.; Um, Wooyong; Parker, Kent E.; Mattigod, Shas V.; Skaggs, Richard

2007-10-15

12

N2 and H2 adsorption behavior of KOH-activated ordered mesoporous carbon  

NASA Astrophysics Data System (ADS)

Ordered mesoporous carbon, referred to as CMK-3, was synthesized by replication from SBA-15. Activated CMK-3 with developed pore structures provided a large surface area and higher hydrogen adsorption capacities after KOH activation at 1073-1223 K. To characterize the pore structure of the activated samples, N2 and H2 adsorption were measured at 77 K. The hydrogen adsorption of activated CMK-3 increased to 2.26 wt.% at an activation temperature of 1173 K due to the formation of micropores. Thus, KOH activation was not only one of the most effective methods for developing porosity, but also raised the hydrogen storage capacity of CMK-3.

Lee, Sang Moon; Lee, Soon Chang; Hong, Won G.; Kim, Hae Jin

2012-12-01

13

[Adsorption kinetics and mechanism of lead (II) on polyamine-functionalized mesoporous activated carbon].  

PubMed

Bagasse mesoporous carbon was prepared by microwave assisted H3 PO4 activation. Amido and imido groups were modified with ethanediamine on the channels' surface of mesoporous carbon through nitric oxidation and amide reaction. The influence of Pb(II) concentration, adsorption time on Pb(II) adsorption on the ethanediamine-modified mesoporous carbon (AC-EDA) was investigated. The adsorption kinetics and mechanism were also discussed. The results showed that AC-EDA had a great performance for Pb(II) adsorption, and more than 70% of Pb(II) was adsorbed in 5 minutes. The adsorption amount of Pb(II) on the carbon increased with the increase of solution pH in acidic conditions. It was found that AC-EDA had different binding energies on different adsorption sites for Pb(II) separation. The Pb(II) adsorption process on AC-EDA was controlled by intra-particle diffusion in the first 3 min, and then film diffusion played the important pole on the adsorption. The adsorption amount increased with the increase of temperature, indicating the adsorption was an endothermic reaction. The high adsorption energy (> 11 kJ x mol(-1)) implied that the) adsorption was a chemical adsorption. The XPS of AC-EDA before and after Pb(II) adsorption showed that the polyamine group was involved in the adsorption, and should be a main factor of the high efficient adsorption. PMID:25338399

Li, Kun-Quan; Wang, Yan-Jin; Yang, Mei-Rong; Zhu, Zhi-Qiang; Zheng, Zheng

2014-08-01

14

Aggregation-free gold nanoparticles in ordered mesoporous carbons: toward highly active and stable heterogeneous catalysts.  

PubMed

A coordination-assisted synthetic approach is reported here for the synthesis of highly active and stable gold nanoparticle catalysts in ordered mesoporous carbon materials using triblock copolymer F127 as a structure-directing agent, thiol-containing silane as a coordination agent, HAuCl4 as a gold source, and phenolic resin as a carbon source. Upon carbonization, the gold precursor becomes reduced to form monodispersed Au nanoparticles of ca. 9.0 nm, which are entrapped or confined by the "rigid" mesoporous carbonaceous framework. Nanoparticle aggregation is inhibited even at a high temperature of 600 °C. After removal of the silica component, the materials possess the ordered mesostructure, high surface area (~1800 m(2)/g), large pore volume (~1.19 cm(3)/g), and uniform bimodal mesopore size (<2.0 and 4.0 nm). The monodispersed gold nanoparticles are highly exposed because of the interpenetrated bimodal pores in the carbon framework, which exhibit excellent catalytic performance. A completely selective conversion of benzyl alcohol in water to benzoic acid can be achieved at 90 °C and 1 MPa oxygen. Benzyl alcohol can also be quantitatively converted to benzoic acid at 60 °C even under an atmospheric pressure, showing great advantages in green chemistry. The catalysts are stable, poison resistant, and reusable with little activity loss due to metal leaching. The silane coupling agent played several functions in this approach: (1) coordinating with gold species by the thiol group to benefit formation of monodispersed Au nanoparticles; (2) reacting with phenolic resins by silanol groups to form relatively "rigid" composite framework; (3) pore-forming agent to generate secondary pores in carbon pore walls, which lead to higher surface area, larger pore volumes, and higher accessibility to to the gold nanoparticles. Complete removal of the silica component proves to have little effect on the catalytic performance of entrapped Au nanoparticles. PMID:23865622

Wang, Shuai; Zhao, Qingfei; Wei, Huimin; Wang, Jian-Qiang; Cho, Minhyung; Cho, Hae Sung; Terasaki, Osamu; Wan, Ying

2013-08-14

15

Characterization of mesoporous carbon prepared from date stems by H3PO4 chemical activation  

NASA Astrophysics Data System (ADS)

The present work was focused on the determination of texture, morphology, crystanillity and oxygenated surface groups characteristics of an activated carbon prepared from date stems. Chemical activation of this precursor at different temperatures (450, 550 and 650 °C) was adopted using phosphoric acid as dehydrating agent at (2/1) impregnation ratio. Fourier transform infrared spectroscopy study was carried out to identify surface groups in date stems activated carbons. The microscopic structure was examined by nitrogen adsorption at 77 K. The interlayer spacing (d200 and d100), stack height (Lc), stack width (La) and effective dimension L of the turbostratic crystallites (microcrystallite) in the date stems activated carbons were estimated from X-ray diffraction data (XRD). Results yielded a surface area, SBET, and total pore volume of 682, 1455, 1319 m2/g and 0,343, 1,045 and 0.735 cm3/g, for the carbon prepared at 450, 550 and 650 °C, respectively. Scanning electron microscopy exhibits a highly developed porosity which is in good agreement with the porous texture derived from gas adsorption data and these results confirm that the activated carbon is dominated by network of slit-shaped mesopores morphology and in some cases by varied micropores morphologies.

Hadoun, H.; Sadaoui, Z.; Souami, N.; Sahel, D.; Toumert, I.

2013-09-01

16

Ordered mesoporous porphyrinic carbons with very high electrocatalytic activity for the oxygen reduction reaction.  

PubMed

The high cost of the platinum-based cathode catalysts for the oxygen reduction reaction (ORR) has impeded the widespread application of polymer electrolyte fuel cells. We report on a new family of non-precious metal catalysts based on ordered mesoporous porphyrinic carbons (M-OMPC; M = Fe, Co, or FeCo) with high surface areas and tunable pore structures, which were prepared by nanocasting mesoporous silica templates with metalloporphyrin precursors. The FeCo-OMPC catalyst exhibited an excellent ORR activity in an acidic medium, higher than other non-precious metal catalysts. It showed higher kinetic current at 0.9 V than Pt/C catalysts, as well as superior long-term durability and MeOH-tolerance. Density functional theory calculations in combination with extended X-ray absorption fine structure analysis revealed a weakening of the interaction between oxygen atom and FeCo-OMPC compared to Pt/C. This effect and high surface area of FeCo-OMPC appear responsible for its significantly high ORR activity. PMID:24056308

Cheon, Jae Yeong; Kim, Taeyoung; Choi, Yongman; Jeong, Hu Young; Kim, Min Gyu; Sa, Young Jin; Kim, Jaesik; Lee, Zonghoon; Yang, Tae-Hyun; Kwon, Kyungjung; Terasaki, Osamu; Park, Gu-Gon; Adzic, Radoslav R; Joo, Sang Hoon

2013-01-01

17

Highly Stable and Active Pt-Cu Oxygen Reduction Electrocatalysts Based on Mesoporous Graphitic Carbon Supports  

SciTech Connect

The activity of oxygen reduction catalysts for fuel cells often decreases markedly (30-70%) during potential cycling tests designed to accelerate catalyst degradation. Herein we achieved essentially no loss in electrochemical surface area and catalyst activity during potential cycling from 0.5 to 1.2 V for presynthesized Pt-Cu nanoparticles of controlled composition that were infused into highly graphitic disordered mesoporous carbons (DMC). The high stability is favored by the strong metal-support interactions and low tendency for carbon oxidation, which mitigates the mechanisms of degradation. Electrochemical dealloying transforms the composition from Pt{sub 20}Cu{sub 80} to Pt{sub 85}Cu{sub 15} with a strained Pt-rich shell, which exhibits an enhanced ORR activity of 0.46 A/mg{sub Pt}, >4 fold that of pure Pt catalysts. The high uniformity in particle size and composition both before and after dealloying, as a consequence of the presynthesis/infusion technique, is beneficial for elucidating the mechanism of catalyst activity and, ultimately, for designing more active catalysts.

Dai, Sheng [ORNL; Gupta, Gaurav [University of Texas, Austin; Kumar, Pavan [University of Texas, Austin; Wiggins-camacho, Jaclyn [University of Texas, Austin; Wang, Xiqing [ORNL; Swinnea, Steven [University of Texas, Austin; More, Karren Leslie [ORNL; Stevenson, Keith J [ORNL; Johnston, Keith [University of Texas, Austin

2009-01-01

18

Highly enhanced capacitance of MgO-templated mesoporous carbons in low temperature ionic liquids  

NASA Astrophysics Data System (ADS)

MgO-templated mesoporous carbons with high specific surface areas were employed for the electrode materials of electric double layer capacitors (EDLCs) in low temperature ionic liquids. The mesoporous carbons exhibit strongly enhanced capacitance in ionic liquids at 20 to -40 °C compared to conventional activated carbons. Mesopores in the carbon electrodes provide a smooth pathway for the ions, and minimize the temperature influence on the diffusion resistance of the ions. Thus, this paper confirms that mesoporous carbons work as electrode materials to achieve highly enhanced capacitances below 0 °C in ionic liquids, which leads to wide ranging applications of EDLC devices.

Kado, Yuya; Imoto, Kiyoaki; Soneda, Yasushi; Yoshizawa, Noriko

2014-12-01

19

Biocompatibility of soft-templated mesoporous carbons.  

PubMed

Soft-templated mesoporous carbon is morphologically a non-nano type of carbon. It is a relatively newer variety of biomaterial, which has already demonstrated its successful role in drug delivery applications. To investigate the toxicity and biocompatibility, we introduced three types of mesoporous carbons with varying synthesis conditions and pore textural properties. We compared the Brunauer-Emmett-Teller (BET) surface area and pore width and performed cytotoxicity experiments with HeLa cells, cell viability studies with fibroblast cells and hemocomapatibility studies. Cytotoxicity tests reveal that two of the carbons are not cytotoxic, with cell survival over 90%. The mesoporous carbon with the highest surface area showed slight toxicity (? 70% cell survival) at the highest carbon concentration of 500 ?g/mL. Fibroblast cell viability assays suggested high and constant viability of over 98% after 3 days with no apparent relation with materials property and good visible cell-carbon compatibility. No hemolysis (<1%) was confirmed for all the carbon materials. Protein adsorption experiments with bovine serum albumin (BSA) and fibrinogen revealed a lower protein binding capacity of 0.2-0.6 mg/m(2) and 2-4 mg/m(2) for BSA and fibrinogen, respectively, with lower binding associated with an increase in surface area. The results of this study confirm the biocompatibility of soft-templated mesoporous carbons. PMID:25144129

Gencoglu, Maria F; Spurri, Amanda; Franko, Mitchell; Chen, Jihua; Hensley, Dale K; Heldt, Caryn L; Saha, Dipendu

2014-09-10

20

Adsorption characteristics of arsenic from micro-polluted water by an innovative coal-based mesoporous activated carbon.  

PubMed

An innovative coal-based mesoporous activated carbon (NCPAC) was prepared by re-agglomeration, oxidation and two-step activation using coal-blending as precursor. Adsorption capacities of As(III) and As(V) ions (<0.5mg/L) onto NCPAC as a function of pH, adsorbent dose, initial arsenic concentrations, contact time, and adsorption isotherms at 7°C was investigated. The innovative methods promoted total pore volume (1.087cm(3)/g), mesoporosity (64.31%), iodine numbers (1104mg/g), methylene blue (251.8mg/g) and ash contents (15.26%). The adsorption capacities of NCPAC for As(III) and As(V) were found to be strongly dependent on pH and contact time. The optimal pH value was 6. The equilibrium time was 60min for adsorption of As(III) and As(V) by NCPAC. The Langmuir model fitted the experimental data well for both As(III) (R(2)=0.9980) and As(V) (R(2)=0.9988). Maximum adsorption capacities of As(III) and As(V) (C0=0.50mg/L) by NCPAC were 1.491 and 1.760mg/g, respectively. PMID:24631151

Li, Wei-Guang; Gong, Xu-Jin; Wang, Ke; Zhang, Xin-Ran; Fan, Wen-Biao

2014-08-01

21

Inorganic–organic hybrid materials based on functionalized silica and carbon: A comprehensive understanding toward the structural property and catalytic activity difference over mesoporous silica and carbon supports  

Microsoft Academic Search

Inorganic–organic hybrid materials based on functionalized silica and carbon were synthesized by anchoring molybdovanadophosphoric acid (H5[PMo10V2O40]·32.5H2O) onto amine-functionalized SBA-15, ethane-bridged SBA-15 and mesoporous carbon, respectively. Small angle X-ray diffraction, N2 sorption analysis, HRTEM, SEM, FT-IR, CP-MAS NMR were used to diagnose the mesoporous structure of inorganic–organic hybrid materials. The structural integrity of molybdovanadophosphoric acid has been found to be retained

Ankur Bordoloi; Nevin T. Mathew; F. Lefebvre; S. B. Halligudi

2008-01-01

22

Three-dimensional micro/mesoporous carbon composites with carbon nanotube networks for capacitive deionization  

NASA Astrophysics Data System (ADS)

The three-dimensional micro/mesoporous carbon composites with carbon nanotube networks for capacitive deionization (CDI) were synthesized through an organic-inorganic self-assemble route with the subsequent activation by KOH. The crucial factors for the textural properties of composites were investigated. It was demonstrated that the new micropores emerge on the mesoporous framework of composites with suitable activation conditions, and some generated micropores also interconnect with others, which gives rise to the broaden pore size in the inner carbon channels and finally forms the efficient three-dimensional micro/mesoporous structure. In the meantime, the activation creates abundant defects on carbon nanotube networks, which also increase the surface area and ion diffusion channels. The electrochemical test shows that the activated composites exhibit the improved electrosorption capacitance. Through the inner resistance and energy density analyses, the activated composite electrode shows a slightly higher resistance but almost an approximate energy density as compared with the pristine one. Meanwhile, the activated composites are revealed to be more effective to adsorb ions in an aqueous solution under a lower CDI voltage, making it possible for the energy saving during CDI procedures. The results mentioned above prove that the activated composites are candidate electrode materials for CDI application, for its high surface area, suitable pore size/volume and special interconnected micro/mesoporous structure, superior electrochemical and CDI performances.

Peng, Zheng; Zhang, Dengsong; Yan, Tingting; Zhang, Jianping; Shi, Liyi

2013-10-01

23

Preparation of free-standing high quality mesoporous carbon membranes  

SciTech Connect

Flat-sheet mesoporous carbon membranes with uniform pore size (e.g., 6.4 nm) and controllable thickness were prepared by pyrolysis of polymeric composite films, which were formed by self-assembly of phenolic resin and block copolymer under acidic conditions. Hexamethylenetetramine was selected as a solid cross-linker to control the rheology of polymeric carbon precursors so that the flat-sheet polymeric films could undergo carbonization without deformation, ensuring the preparation of mesoporous carbon membranes on a large scale with high quality. Gas transport properties through these mesoporous carbon membranes are also reported.

Wang, Xiqing [ORNL; Liang, Chengdu [ORNL; Dai, Sheng [ORNL; Mahurin, Shannon Mark [ORNL; Zhu, Qing [ORNL

2010-01-01

24

The oriented growth of tungsten oxide in ordered mesoporous carbon and their electrochemical performance.  

PubMed

Electrocatalysts for hydrogen oxidation and methanol oxidation are the heart of the proton exchange membrane fuel cell. In spite of tremendous efforts, developing low-cost anodic electrocatalysts with high catalytic activity and corrosion resistance is still a great challenge. Here, we report a nanocomposite consisting of oriented WO3 nanorods grown in ordered mesoporous carbon as a high-performance functional catalyst carrier for proton exchange membrane fuel cells. As a result of the catalytic graphitization effect of tungsten compounds, the degree of graphitization and conductivity of mesoporous carbon film were improved even at a low temperature. Furthermore, compared with ordered mesoporous carbon, ordered mesoporous C-WO3 nanocomposites possess favorable hydrophilicity, excellent corrosion resistance and notable electrocatalytic activities. The unusual electrocatalytic activities arise from the ideal physical properties of the carrier and synergetic catalysis between Pt and WO3. PMID:24733640

Wang, Tao; Tang, Jing; Fan, Xiaoli; Zhou, Jianhua; Xue, Hairong; Guo, Hu; He, Jianping

2014-05-21

25

The oriented growth of tungsten oxide in ordered mesoporous carbon and their electrochemical performance  

NASA Astrophysics Data System (ADS)

Electrocatalysts for hydrogen oxidation and methanol oxidation are the heart of the proton exchange membrane fuel cell. In spite of tremendous efforts, developing low-cost anodic electrocatalysts with high catalytic activity and corrosion resistance is still a great challenge. Here, we report a nanocomposite consisting of oriented WO3 nanorods grown in ordered mesoporous carbon as a high-performance functional catalyst carrier for proton exchange membrane fuel cells. As a result of the catalytic graphitization effect of tungsten compounds, the degree of graphitization and conductivity of mesoporous carbon film were improved even at a low temperature. Furthermore, compared with ordered mesoporous carbon, ordered mesoporous C-WO3 nanocomposites possess favorable hydrophilicity, excellent corrosion resistance and notable electrocatalytic activities. The unusual electrocatalytic activities arise from the ideal physical properties of the carrier and synergetic catalysis between Pt and WO3.Electrocatalysts for hydrogen oxidation and methanol oxidation are the heart of the proton exchange membrane fuel cell. In spite of tremendous efforts, developing low-cost anodic electrocatalysts with high catalytic activity and corrosion resistance is still a great challenge. Here, we report a nanocomposite consisting of oriented WO3 nanorods grown in ordered mesoporous carbon as a high-performance functional catalyst carrier for proton exchange membrane fuel cells. As a result of the catalytic graphitization effect of tungsten compounds, the degree of graphitization and conductivity of mesoporous carbon film were improved even at a low temperature. Furthermore, compared with ordered mesoporous carbon, ordered mesoporous C-WO3 nanocomposites possess favorable hydrophilicity, excellent corrosion resistance and notable electrocatalytic activities. The unusual electrocatalytic activities arise from the ideal physical properties of the carrier and synergetic catalysis between Pt and WO3. Electronic supplementary information (ESI) available: Additional structural characterizations and electrochemical measurements. See DOI: 10.1039/c4nr00396a

Wang, Tao; Tang, Jing; Fan, Xiaoli; Zhou, Jianhua; Xue, Hairong; Guo, Hu; He, Jianping

2014-04-01

26

Rapid removal of bisphenol A on highly ordered mesoporous carbon.  

PubMed

Bisphenol A (BPA) is of global concern due to its disruption of endocrine systems and ubiquity in the aquatic environment. It is important, therefore, that efforts are made to remove it from the aqueous phase. A novel adsorbent, mesoporous carbon CMK-3, prepared from hexagonal SBA-15 mesoporous silica was studied for BPA removal from aqueous phase, and compared with conventional powdered activated carbon (PAC). Characterization of CMK-3 by transmission electron microscopy (TEM), X-ray diffraction, and nitrogen adsorption indicated that prepared CMK-3 had an ordered mesoporous structure with a high specific surface area of 920 m2/g and a pore-size of about 4.9 nm. The adsorption of BPA on CMK-3 followed a pseudo second-order kinetic model. The kinetic constant was 0.00049 g/(mg x min), much higher than the adsorption of BPA on PAC. The adsorption isotherm fitted slightly better with the Freundlich model than the Langmuir model, and adsorption capacity decreased as temperature increased from 10 to 40 degrees C. No significant influence of pH on adsorption was observed at pH 3 to 9; however, adsorption capacity decreased dramatically from pH 9 to 13. PMID:21516989

Sui, Qian; Huang, Jun; Liu, Yousong; Chang, Xiaofeng; Ji, Guangbin; Deng, Shubo; Xie, Tao; Yu, Gang

2011-01-01

27

Mesoporous carbon for capacitive deionization of saline water.  

PubMed

Self-assembled mesoporous carbon (MC) materials have been synthesized and tested for application in capacitive deionization (CDI) of saline water. MC was prepared by self-assembly of a triblock copolymer with hydrogen-bonded chains via a phenolic resin, such as resorcinol or phloroglucinol in acidic conditions, followed by carbonization and, in some cases, activation by KOH. Carbon synthesized in this way was ground into powder, from which activated MC sheets were produced. In a variation of this process, after the reaction of triblock copolymer with resorcinol or phloroglucinol, the gel that was formed was used to coat a graphite plate and then carbonized. The coated graphite plate in this case was not activated and was tested to serve as current collector during the CDI process. The performance of these MC materials was compared to that of carbon aerogel for salt concentrations ranging between 1000 ppm and 35,000 ppm. Resorcinol-based MC removed up to 15.2 mg salt per gram of carbon, while carbon aerogel removed 5.8 mg salt per gram of carbon. Phloroglucinol-based MC-coated graphite exhibited the highest ion removal capacity at 21 mg of salt per gram of carbon for 35,000 ppm salt concentration. PMID:22032802

Tsouris, C; Mayes, R; Kiggans, J; Sharma, K; Yiacoumi, S; DePaoli, D; Dai, S

2011-12-01

28

Mesoporous Carbon for Capacitive Deionization of Saline Water  

SciTech Connect

Self-assembled mesoporous carbon (MC) materials have been synthesized and tested for application in capacitive deionization (CDI) of saline water. MC was prepared by self-assembly of a triblock copolymer with hydrogen-bonded chains via a phenolic resin, such as resorcinol or phloroglucinol in acidic conditions, followed by carbonization and, in some cases, activation by KOH. Carbon synthesized in this way was ground into powder, from which activated MC sheets were produced. In a variation of this process, after the reaction of triblock copolymer with resorcinol or phloroglucinol, the gel that was formed was used to coat a graphite plate and then carbonized. The coated graphite plate in this case was not activated and was tested to serve as current collector during the CDI process. The performance of these MC materials was compared to that of carbon aerogel for salt concentrations ranging between 1000 ppm and 35,000 ppm. Resorcinol-based MC removed up to 15.2 mg salt per gram of carbon, while carbon aerogel removed 5.8 mg salt per gram of carbon. Phloroglucinol-based MC-coated graphite exhibited the highest ion removal capacity at 21 mg of salt per gram of carbon for 35,000 ppm salt concentration.

Tsouris, Costas [ORNL; Mayes, Richard T [ORNL; Kiggans, Jim [ORNL; Sharma, Ms. Ketki [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; DePaoli, David W [ORNL; Dai, Sheng [ORNL

2011-01-01

29

Optimization of mesoporous carbon structures for lithiumâsulfur battery applications  

Microsoft Academic Search

Mesoporous carbon (MC) with tunable pore sizes (22nm, 12nm, 7nm, and 3nm) and pore volumes (from 1.3 to 4.8 cc\\/g) containing sulfur inside the pores were systematically studied as mesoporous carbon-sulfur (MCS) composite electrodes for Li-S batteries. Investigation on these MCS composites reveals that the pore structure has no influence on the battery performance at full sulfur loading conditions (the

Xiaolin Li; Yuliang Cao; Wen N. Qi; Laxmikant V. Saraf; Jie Xiao; Zimin Nie; Jaroniec Mietek; Jiguang Zhang; Birgit Schwenzer; Jun Liu

2011-01-01

30

Carbon dioxide capture using polyethylenimine-loaded mesoporous carbons.  

PubMed

A high efficiency sorbent for CO2 capture was developed by loading polyethylenimine (PEI) on mesoporous carbons which possessed well-developed mesoporous structures and large pore volume. The physicochemical properties of the sorbent were characterized by N2 adsorption/desorption, scanning electron microscopy (SEM), thermal gravimetric analysis (TG) and Fourier transform infrared spectroscopy (FT-IR) techniques followed by testing for CO2 capture. Factors that affected the sorption capacity of the sorbent were studied. The sorbent exhibited extraordinary capture capacity with CO2 concentration ranging from 5% to 80%. The optimal PEI loading was determined to be 65 wt.% with a CO2 sorption capacity of 4.82 mmol-CO2/g-sorbent in 15% CO2/N2 at 75 degrees C, owing to low mass-transfer resistance and a high utilization ratio of the amine compound (63%). Moisture had a promoting effect on the sorption separation of CO2. In addition, the developed sorbent could be regenerated easily at 100 degrees C, and it exhibited excellent regenerability and stability. These results indicate that this PEI-loaded mesoporous carbon sorbent should have a good potential for CO2 capture in the future. PMID:23586307

Wang, Jitong; Chen, Huichao; Zhou, Huanhuan; Liu, Xiaojun; Qiao, Wenming; Long, Donghui; Ling, Licheng

2013-01-01

31

Ordered mesoporous carbons obtained by a simple soft template method as sulfur immobilizers for lithium-sulfur cells.  

PubMed

Carbon materials with ordered mesoporous structures were synthesized using soft template methods and then activated by CO2 treatment. Sulfur was incorporated in these carbons via a simple chemical deposition method in aqueous solutions and the resulting composites were tested as electrodes in Li-S cells. The electrochemical results showed that well-ordered mesoporous carbons perform better than those with a random mesopore arrangement (wormhole-like mesoporous structure). The mesopore ordering yields a framework of well-connected empty sites that results in an enhancement of both the charge carrier mobility and the reversibility of the electrochemical reaction. Although the activation with CO2 partially destroys the mesopore arrangement, which adversely affects the electrode performance, it notably increases the surface area and the micropore content which improves the connectivity between the mesopores. The final observation was an irrelevant effect of the activation process at low current densities. However, at higher rates the activated carbon composite delivered higher capacities. The hierarchical pore structure formed by micro- and mesopores should guarantee the required fast mobility of the Li(+). PMID:25019261

Moreno, Noelia; Caballero, Alvaro; Hernán, Lourdes; Morales, Julián; Canales-Vázquez, Jesús

2014-08-28

32

Facile synthesis of carbon-doped mesoporous anatase TiO2 for the enhanced visible-light driven photocatalysis.  

PubMed

Here we report a low-cost and facile synthesis approach for carbon-doped mesoporous anatase TiO2 by using Ti(BuO)4 as a source for both Ti and carbon through xerogel carbonization in a hypoxic atmosphere. The resultant mesoporous C-TiO2 with high crystallinity exhibits excellent photocatalytic activities for degradation of methyl orange (MO) and phenol under visible light irradiation. PMID:25266327

Liu, Juming; Zhang, Qiancheng; Yang, Jucai; Ma, Huiyan; Tade, Moses O; Wang, Shaobin; Liu, Jian

2014-10-16

33

Mesoporous Carbon-based Materials for Alternative Energy Applications  

NASA Astrophysics Data System (ADS)

Increasing concerns for the escalating issues activated by the effect of carbon dioxide emissions on the global climate from extensive use of fossil fuels and the limited amount of fossil resources has led to an in-depth search for alternative energy systems, primarily based on nuclear or renewable energy sources. Recent innovations in the production of more efficient devices for energy harvesting, storage, and conversion are based on the incorporation of nanostructured materials into electrochemical systems. The aforementioned nano-electrochemical energy systems hold particular promise for alternative energy transportation related technologies including fuel cells, hydrogen storage, and electrochemical supercapacitors. In each of these devices, nanostructured materials can be used to increase the surface area where the critical chemical reactions occur within the same volume and mass, thereby increasing the energy density, power density, electrical efficiency, and physical robustness of the system. Durable corrosion resistant carbon support materials for fuel cells have been designed by adding conductive low cost carbon materials with chemically robust ceramic materials. Since a strict control of the pore size is mandatory to optimize properties for improved performance, chemical activation agents have been utilized as porogens to tune surface areas, pore size distributions, and composition of carbon-based mesoporous materials. Through the use of evaporative self-assembly methods, both randomly disordered and surfactant-templated, ordered carbon-silica nanocomposites have been synthesized with controlled surface area, pore volume, and pore size ranging from 50-800 m2/g, 0.025-0.75 cm3/g, and 2-10 nm, respectively. Multi-walled carbon nanotubes (MWNTs) ranging from 0.05-1.0 wt. % were added to the aforementioned carbon-silica nanocomposites, which provided an additional increase in surface area and improved conductivity. Initially, a conductivity value of 0.0667 S/cm was measured for the composite without carbon nanotubes and the conductivity value improved by over an order of magnitude to 1 S/cm with the addition of 0.5 wt.% CNTs. Triggered by dispersion issues, the agglomeration of MWNTs during the drying process prevented each nanotube from being loaded over a maximum interfacial area. In order to improve the dispersion of carbon nanotubes within the carbon-silica network, electrospinning was explored as a method to improve the alignment of the carbon nanotubes. The electrospun fibers produced with the highest concentration of MWNTs at 1.0 wt.% produced the largest surface area and electrical conductivity values of 333.36 m2/g and 2.09 S/cm, respectively. Capacitance measurements were calculated to examine if improved conductivity results in higher capacitance values. The best capacitance performance was 148 F/g from a carbon-based mesoporous composite with 0.5 wt. % MWNTs in an aqueous electrolyte with a 2.0 mV/s scan rate. An 80% increase in capacitance occurs with the addition of 0.5 wt. % MWNTs. This is in the range of capacitance values produced by hierarchically ordered mesoporous-microporous carbons, reported at 180 F/g. Fibrous carbon tubes assembled from hydrofluoric acid etched perylenetetracarboxylic diimide bridged silsesquioxane (PDBS) were capable of hydrogen adsorption on the order of 1.3-2.5 wt. % at 77K. Lastly chemically activated phenol-formaldehyde resins produced microporous carbon with 1500 m3/g surface areas and pore sizes ranging from 0.3-0.5 nm, which has potential for asymmetric super-capacitor electrodes. Judicious control over the composition and pore structure of carbon-based nanocomposites can lead to improved performance of various alternative energy materials.

Cross, Kimberly Michelle

34

Simple synthesis of mesoporous carbon nanofibers with hierarchical nanostructure for ultrahigh lithium storage.  

PubMed

In this study, a simple and reproducible synthesis strategy was developed to fabricate mesoporous carbon nanofibers (MCNFs) by using dual hard templates, a porous anodic aluminum oxide (AAO) membrane, and colloidal silica (Ludox TM-40). By using commercial templates, and removing AAO and the silica simultaneously, the synthesis procedures for MCNFs are greatly simplified without the need for separate preparation or the removal of templates in sequence. With phenol resin as a carbon precursor, the as-prepared MCNFs material reveals not only high surface area and mesoporous volume but also hierarchical nanostructure composed of hollow macrochannels derived from the AAO template, large mesopores (ca. 22 nm) from the removal of silica particles and micropores from the carbonization of phenol resin. Such unique surface and structural characteristics could provide a large quantity of active sites for Li storage and facilitate fast mass transport. Moreover, a one-dimensional (1D) carbon nanofiber (CNF) nanostructure favors fast electron transfer. The as-prepared MCNF anode demonstrates ultrahigh lithium storage capacity particularly at high rates, which is much higher than that reported for the commercial graphite and also significantly higher than other nanostructured carbon materials, such as ordered mesoporous carbon CMK-3 and ordered multimodal porous carbon (OMPC). PMID:24490802

Xing, Yalan; Wang, Yanjie; Zhou, Chungen; Zhang, Shichao; Fang, Baizeng

2014-02-26

35

Reversible replication between ordered mesoporous silica and mesoporous carbon  

E-print Network

.0 g of the CMK-3 was slurried in an aqueous solution containing 2.0 g of Na2SiO3 at room temperature For CMK-3, calcined SBA-15 and sucrose were used as the template and the carbon source, respectively.7

Kim, Ji Man

36

Mesoporous carbons derived from citrates for use in electrochemical capacitors  

Microsoft Academic Search

Two mesoporous carbons were prepared by simple pyrolysis of commercial magnesium or barium citrate and tested as electrode materials for electrochemical double-layer capacitors (EDLCs), denoted MgC and BaC, respectively. The as-prepared carbon materials were characterized by N2 adsorption, scanning electron microscopy and Fourier transform infrared spectrometry. Nitrogen adsorption measurements demonstrated that the porosity of the prepared carbons was related to

Jin ZHOU; Xun YUAN; Wei XING; Wei-jiang SI; Shu-ping ZHUO

2010-01-01

37

Hydrogen Storage on Metal-Doped Ordered Mesoporous Carbons  

E-print Network

Meeting, May 18, 2010 #12;Outline · Research group · Hydrogen storage: background and status · SynthesisHydrogen Storage on Metal-Doped Ordered Mesoporous Carbons Shuguang Deng New Mexico State of pure and metal-doped OMC · Characterization of metal-doped OMC · Hydrogen adsorption equilibrium

Johnson, Eric E.

38

Soft-Template-Synthesized Mesoporous Carbon for Oral Drug Delivery  

SciTech Connect

Template-synthesized mesoporous carbons were successfully used in in vitro investigations of controlled delivery of three model drugs, captopril, furosemide, and ranitidine hydrochloride. Captopril and furosemide exhibited desorption kinetics over 30 40 h, and ranitidine HCl had a complete release time of 5 10 h. As evident from the slow release kinetics, we contend that our mesoporous carbon is an improved drug-delivery medium compared to state-of-the-art porous silica-based substrates. The mesoporous carbons, synthesized from phloroglucinol and lignin, a synthetic and a sustainable precursor, respectively, exhibit BET surface area of 200 400 m2 g-1 and pore volume of 0.2 0.6 cm3 g-1. The phloroglucinol-based carbon has narrower pore widths and higher pore volume than the lignin-derived counterpart and maintains a longer release time. Numerical modeling of the release kinetics data reveals that the diffusivities of all the drugs from lignin-based carbon media are of equivalent magnitude (10-22 to 10-24 m2 s-1). However, a tailored reduction of pore width in the sorbent reduces the diffusivity of smaller drug molecules (captopril) by an order of magnitude. Thus, engineered pore morphology in our synthesized carbon sorbent, along with its potential to tailor the chemistry of its interaction with sorbet, can be exploited for optimal delivery system of a preferred drug within its therapeutic level and below the level of toxicity.

Saha, Dipendu [ORNL] [ORNL; Warren, Kaitlyn E [ORNL] [ORNL; Naskar, Amit K [ORNL] [ORNL

2014-01-01

39

Graphitic mesoporous carbon as a durable fuel cell catalyst support  

SciTech Connect

Highly stable graphitic mesoporous carbons (GMPCs) are synthesized by heat-treating polymer-templated mesoporous carbon (MPC) at 2600 C. The electrochemical durability of GMPC as Pt catalyst support (Pt/GMPC) is compared with that of carbon black (Pt/XC-72). Comparisons are made using potentiostatic and cyclic voltammetric techniques on the respective specimens under conditions simulating the cathode environment of PEMFC (proton exchange membrane fuel cell). The results indicate that the Pt/GMPC is much more stable than Pt/XC-72, with 96% lower corrosion current. The Pt/GMPC also exhibits a greatly reduced loss of catalytic surface area: 14% for Pt/GMPC vs. 39% for Pt/XC-72.

Dai, Sheng [ORNL; Liang, Chengdu [ORNL; Shanahan, Paul [University of California; Xu, Lianbin [University of California; Waje, Mahesh [University of California; Yan, Y.S. [University of California

2008-01-01

40

Preparation and functionalization of mesoporous silica, carbon and silica/carbon nanocomposites  

NASA Astrophysics Data System (ADS)

The synthesis of mesostructured materials including mesoporous silica, carbon and carbon-silica nanocomposites has become one of the leading topics in materials science because the mesostructured materials carry many unique properties such as high surface area, large and controllable pore size and structures, uniform pore size distributions and large pore volumes, which make the mesoporous materials many potential applications, for example catalyst supports, adsorbent for large molecules, hydrogen adsorption media, etc. Template synthesis, a unique approach that utilizes hard (preformed nanostructured inorganic frameworks or nanoparticles) and/or soft templates (liquid crystal phase of amphiphilic molecules) to organize precursor building blocks into large controllable structures, has emerged as the most promising method to fabricate mesostructured materials. Besides the mesostructure control, functionalization of mesoporous materials has also been a focus, because the functionalized organic groups may provide mesoporous materials with improved surface properties. This dissertation addresses the synthesis of mesoporous materials through template techniques including aerosol-assisted self-assembly and evaporation induced self-assembly methods. The functionalized mesoporous silica can be prepared by one-step co-condensation of TEOS and organosiline and co-assembly with amphiphilic molecular template. The mesostructure, pore size and morphology control can be realized by using different templates, synthesis methods and synthesis conditions. The content of hydrophobic molecule in the precursor solution also has dramatic effect on the mesostructures of obtained mesoporous silica particles. Both hard and soft templates are used to synthesize mesoporous carbon and carbon-based nanocomposites with tunable pore size, structures and morphologies. The applications of obtained mesoporous materials, such as catalysis and adsorption are discussed.

Hu, Qingyuan

41

Noncovalently functionalized graphitic mesoporous carbon as a stable support of Pt nanoparticles for oxygen reduction  

SciTech Connect

We report the facile synthesis of an extremely durable electrocatalyst for oxygen reduction with highly graphitized mesoporous carbon (GMPC) as support (Pt/GMPC). GMPC is prepared through graphitizing the self-assembled soft-template mesoporous carbon (MPC) under high temperature. Most of the mesoporous structures and the specific surface area of MPC are retained even after 2800 °C heat-treatment, and the graphitization degree is greatly improved. GMPC is then noncovalently functionalized with poly(diallyldimethylammonium chloride) (PDDA) and then coated with Pt nanoparticles with ethylene glycol reduction method. Pt nanoparticles of ~3.0 nm in diameter are uniformly dispersed on GMPC. Pt/GMPC exhibits a higher activity towards oxygen reduction reaction (ORR) than Pt nanoparticles supported on Vulcan XC-72 carbon (Pt/XC-72). The durability of Pt/GMPC is improved by a factor of ~2 compared with Pt/XC-72. The enhanced activity and durability of Pt/GMPC are attributed to the graphitic structure of GMPC which makes GMPC more resistant to corrosion and the interaction between Pt nanoparticles and GMPC stronger. GMPC is promising as catalyst support. This provides a facile, eco-friendly promising strategy, avoiding the usually used chemical functionalization of carbon support with oxidizing strong acid, to synthesize electrocatalysts with high durability and activity for polymer electrolyte membrane fuel cells. This strategy can be widely applied in synthesizing metal nanoparticles on hydrophobic support materials.

Shao, Yuyan; Zhang, Sheng; Kou, Rong; Wang, Xiqing; Wang, Chong M.; Dai, Sheng; Viswanathan, Vilayanur V.; Liu, Jun; Wang, Yong; Lin, Yuehe

2010-01-01

42

Synthesis of white light emitting mesoporous carbon-silica nanocomposite  

NASA Astrophysics Data System (ADS)

White light emitting mesoporous carbon-silica (MPCS) was synthesized by serially adding triblock copolymer (Pluronic, F127), ethanol (EtOH), tetraethoxysilane (TEOS), hydrochloric acid aqueous (HCl) and phenol-formaldehyde resin (resol) followed by the heat treatments of carbonization and oxidation. The PL intensity of MPCS showed a tendency to be strong with increasing of HCl concentration in >= 0.2 M. The pore size of MPCS that emits white light was 8 ~ 9 nm and the specific surface area was 320 ~ 418 m2 / g.

Sato, Koji; Ishikawa, Yukari; Matsumura, Akihiro; Ishii, Yosuke; Kawasaki, Shinji

2011-05-01

43

Microporosity development in phenolic resin-based mesoporous carbons for enhancing CO2 adsorption at ambient conditions  

NASA Astrophysics Data System (ADS)

Soft-templating method was used to prepare mesoporous carbons. The synthesis in the presence of hydrochloric and citric acids involved resorcinol and formaldehyde as carbon precursors and triblock copolymer Pluronic F127 as a template. The as-synthesized samples underwent carbonization in flowing nitrogen at various temperatures; namely 600 °C, 700 °C and 800 °C. Two routes were used to develop microporosity in the mesoporous carbons studied. The first one involved introduction of tetraethyl orthosilicate to the reaction system. After silica dissolution with NaOH, an increase in microporosity was observed. The second method, chemical activation with KOH at 700 °C, was explored as an alternative approach to create microporosity. It is noteworthy that the TEOS addition not only led to the development of microporosity but also to some improvement of mesoporosity. The post-synthesis KOH activation resulted in more significant increase in the microporosity as compared to the samples obtained by TEOS-assisted synthesis. The mesopore volume was somewhat lower for activated carbons as compared to that in mesoporous carbons. Both methods resulted in micro-mesoporous carbons with good adsorption properties; for instance, in the case of carbons prepared in the presence of TEOS, the best sample exhibited BET surface area of 1463 m2/g and the total pore volume of 1.31 cm3/g. For the KOH activated carbons the best adsorption parameters were as follows: the specific surface area = 1906 m2/g, and the total pore volume = 0.98 cm3/g. Both procedures used for microporosity development afforded carbons with good adsorption properties that can be useful for applications such as CO2 adsorption, air and water purification.

Choma, Jerzy; Jedynak, Katarzyna; Fahrenholz, Weronika; Ludwinowicz, Jowita; Jaroniec, Mietek

2014-01-01

44

Noncovalently functionalized graphitic mesoporous carbon as a stable support of Pt nanoparticles for oxygen reduction  

SciTech Connect

We report a durable electrocatalyst support, highly graphitized mesoporous carbon (GMPC), for oxygen reduction in polymer electrolyte membrane (PEM) fuel cells. GMPC is prepared through graphitizing the self-assembled soft-template mesoporous carbon (MPC) under high temperature. Heat-treatment at 2800 C greatly improves the degree of graphitization while most of the mesoporous structures and the specific surface area of MPC are retained. GMPC is then noncovalently functionalized with poly(diallyldimethylammonium chloride) (PDDA) and loaded with Pt nanoparticles by reducing Pt precursor (H{sub 2}PtCl{sub 6}) in ethylene glycol. Pt nanoparticles of {approx}3.0 nm in diameter are uniformly dispersed on GMPC. Compared to Pt supported on Vulcan XC-72 carbon black (Pt/XC-72), Pt/GMPC exhibits a higher mass activity towards oxygen reduction reaction (ORR) and the mass activity retention (in percentage) is improved by a factor of {approx}2 after 44 h accelerated degradation test under the potential step (1.4-0.85 V) electrochemical stressing condition which focuses on support corrosion. The enhanced activity and durability of Pt/GMPC are attributed to the graphitic structure of GMPC which is more resistant to corrosion. These findings demonstrate that GMPC is a promising oxygen reduction electrocatalyst support for PEM fuel cells. The approach reported in this work provides a facile, eco-friendly promising strategy for synthesizing stable metal nanoparticles on hydrophobic support materials.

Wang, Xiqing [ORNL; Dai, Sheng [ORNL; Engelhard, Mark H [Pacific Northwest National Laboratory (PNNL); Wang, Congmin [ORNL; Liu, Jun [Pacific Northwest National Laboratory (PNNL); YANG, ZHENGUO [Pacific Northwest National Laboratory (PNNL); Lin, Yuehe [ORNL; Shao, Yuyan [Pacific Northwest National Laboratory (PNNL)

2010-01-01

45

Direct Electrochemistry and Electrocatalysis of Hemoglobin at Mesoporous Carbon Modified Electrode  

PubMed Central

The novel highly ordered mesoporous carbon (known as FDU-15), prepared by the organic-organic self-assembly method was been used for first time for the immobilization of hemoglobin (Hb) and its bioelectrochemical properties were studied. The resulting Hb/FDU-15 film provided a favorable microenvironment for Hb to perform direct electron transfers at the electrode. The immobilized Hb also displayed its good electrocatalytic activity for the reduction of hydrogen peroxide. The results demonstrate that mesoporous carbon FDU-15 can improve the Hb loading with retention of its bioactivity and greatly promote the direct electron transfer, which can be attributed to its high specific surface area, uniform ordered porous structure, suitable pore size and biocompatibility. Our present study may provide an alternative way for the construction of nanostructure biofunctional surfaces and pave the way for its application to biosensors. PMID:22205867

Pei, Supeng; Qu, Song; Zhang, Yongming

2010-01-01

46

Sulfonated mesoporous silica-carbon composites and their use as solid acid catalysts  

NASA Astrophysics Data System (ADS)

The synthesis of highly functionalized porous silica-carbon composites made up of sulfonic groups attached to a carbon layer coating the pores of three types of mesostructured silica (i.e. SBA-15, KIT-6 and mesocellular silica) is presented. The synthesis procedure involves the following steps: (a) removal of the surfactant, (b) impregnation of the silica pores with a carbon precursor, (c) carbonization and (d) sulfonation. The resulting silica-carbon composites contain ˜30 wt % of carbonaceous matter with a high density of acidic groups attached to the deposited carbon (i.e.sbnd SO3H, sbnd COOH and sbnd OH). The structural characteristics of the parent silica are retained in the composite materials, which exhibit a high surface area, a large pore volume and a well-ordered porosity made up uniform mesopores. The high density of the sulfonic groups in combination with the mesoporous structure of the composites ensures that a large number of active sites are easily accessible to reactants. These sulfonated silica-carbon composites behave as eco-friendly, active, selective, water tolerant and recyclable solid acids. In this study we demonstrate the usefulness of these composites as solid acid catalysts for the esterification of maleic anhydride, succinic acid and oleic acid with ethanol. These composites exhibit a superior intrinsic catalytic activity to other commercial solid acids such as Amberlyst-15.

Valle-Vigón, Patricia; Sevilla, Marta; Fuertes, Antonio B.

2012-11-01

47

Raspberry derived mesoporous carbon-tubules and fixed-bed adsorption of pharmaceutical drugs  

E-print Network

Raspberry derived mesoporous carbon-tubules and fixed-bed adsorption of pharmaceutical drugs Shashi Department, University of Florida, Gainesville, FL 32611-0290, USA 1. Introduction Pharmaceutical drugs (PD­water partition coefficient Pharmaceutical drugs A B S T R A C T Novel mesoporous carbon-tubules were prepared

Ma, Lena

48

Raspberry derived mesoporous carbon-tubules and fixed-bed adsorption of pharmaceutical drugs  

E-print Network

Raspberry derived mesoporous carbon-tubules and fixed-bed adsorption of pharmaceutical drugs Shashi Department, University of Florida, Gainesville, FL 32611-0290, USA 1. Introduction Pharmaceutical drugs (PD�water partition coefficient Pharmaceutical drugs A B S T R A C T Novel mesoporous carbon-tubules were prepared

Ma, Lena

49

Fabrication and characterization of mesoporous activated carbon from Lemna minor using one-step H3PO4 activation for Pb(II) removal  

NASA Astrophysics Data System (ADS)

A low cost and locally available material, Lemna minor, was used to fabricate activated carbon using H3PO4 activation. After H3PO4 activation, the L. minor activated carbons (LACs) possess high mesoporosity (92.2%) and a surface area of 531.9 m2/g according to Brunauer-Emmett-Teller (BET) analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectrometer (XPS) analyses reveal the presence of rich hydroxyl, carboxyl, amide and phosphate functional groups on the LACs surface, leading to facile Pb(II) binding to the surface through strong chemisorptive bonds or ion-exchange. The kinetic and equilibrium data were well described by pseudo-first-order model and Langmuir isotherm, with the maximum monolayer adsorption capacity (qm) 170.9 mg/g at 25 °C. The intra-particle diffusion mechanism was partially responsible for the adsorption. The adsorption process was spontaneous and endothermic with negative ?G and positive ?H. The Pb(II)-loaded LACs could be easily regenerated using 0.1-M HCl and reused for seven cycles without significant adsorption capacity reduction. The maximum percentage removal rate for Pb(II) (20 mg/L) was found to be 91.8% within 30 min, at optimum conditions of pH 6.0 and 25 °C. These suggested that the low-cost LACs could be used as a potential adsorbent in the treatment of lead-contaminated water.

Huang, Yang; Li, Shunxing; Lin, Haibin; Chen, Jianhua

2014-10-01

50

Bimodal mesoporous carbon synthesized from large organic precursor and amphiphilic tri-block copolymer by self assembly  

SciTech Connect

Owing to several disadvantages of traditional hard template based synthesis, soft-template or self-assembly was adopted to synthesize mesoporous carbon. In this work, we have introduced hexaphenol as a new and large organic precursor for the synthesis of mesoporous carbon by self-assembly with pluronic P123 as structure dictating agent. The resultant mesoporous carbon is bimodal in nature with median pore widths of 29 and 45 and BET surface area of 312 m2/g. Unlike previously synthesized mesoporous carbon, this carbon possesses negligible micropore volume. This mesoporous carbon is very suitable candidate for several applications including membrane separation, chemical sensor or selective sorption of larger molecules.

Saha, Dipendu [ORNL; Contescu, Cristian I [ORNL; Gallego, Nidia C [ORNL

2012-01-01

51

A simple method to ordered mesoporous carbons containing nickel nanoparticles  

SciTech Connect

A series of ordered mesoporous carbons containing magnetic Ni nanoparticles (Ni-OMCs) with a variety of Ni loadings was made by a simple one-pot synthetic procedure through carbonization of phenolic resin-Pluronic block copolymer composites containing various amount of nickel nitrate. Such composite materials were characterized by N{sub 2} sorption, XRD, and STEM. Ni-OMCs exhibited high BET surface area, uniform pore size, and large pore volume without obvious pore blockage with a Ni loading as high as 15 wt%. Ni nanoparticles were crystalline with a face-center-cubic phase and observed mainly in the carbon matrix and on the outer surface as well. The average particle size of Ni nanoparticles was dependent on the preparation (carbonization) temperature and Ni loading; the higher the temperature was used and the more the Ni was incorporated, the larger the Ni nanoparticles were observed. One of the applications of Ni-OMCs was demonstrated as magnetically separable adsorbents.

Dai, Sheng [ORNL; Wang, Xiqing [ORNL

2009-01-01

52

Hybrid MnO(2)-disordered mesoporous carbon nanocomposites: synthesis and characterization as electrochemical pseudocapacitor electrodes  

SciTech Connect

MnO{sub 2}-mesoporous carbon hybrid nanocomposites were synthesized to achieve high values of redox pseudocapacitance at scan rates of 100 mV s{sup -1}. High-resolution transmission electron microscopy (HRTEM) along with energy dispersive X-ray spectroscopy (EDX) demonstrated that {approx}1 nm thick MnO{sub 2} nanodomains, resembling a conformal coating, were uniformly distributed throughout the mesoporous carbon structure. HRTEM and X-ray diffraction (XRD) showed formation of MnO{sub 2} nanocrystals with lattice planes corresponding to birnessite. The electrochemical redox pseudocapacitance of these composite materials in aqueous 1 M Na{sub 2}SO{sub 4} electrolyte containing as little as 2 wt% MnO{sub 2} exhibited a high gravimetric MnO{sub 2} pseudocapacitance (C{sub MnO{sub 2}}) of 560 F g{sub MnO{sub 2}}{sup -1}. Even for 30 wt% MnO{sub 2}, a high C{sub MnO{sub 2}} of 137 F g{sub MnO{sub 2}}{sup -1} was observed at 100 mV s{sup -1}. Sodium ion diffusion coefficients on the order of 10{sup -9} to 10{sup -10} cm{sup 2} s{sup -1} were measured using chronoamperometry. The controlled growth and conformal coating of redox-active MnO{sub 2}-mesoporous carbon composites offer the potential for achieving high power energy storage with low cost materials.

Johnston, Keith [University of Texas, Austin; Stevenson, Keith J [ORNL; Dai, Sheng [ORNL; Patel, Mehul [University of Texas, Austin; Wang, Xiqing [ORNL; Wilson, Brian [University of Texas, Austin; Ferrer, Domingo [University of Texas, Austin

2010-01-01

53

Sulfur- and nitrogen-doped, ferrocene-derived mesoporous carbons with efficient electrochemical reduction of oxygen.  

PubMed

Development of inexpensive and sustainable cathode catalysts that can efficiently catalyze the oxygen reduction reaction (ORR) is of significance in practical application of fuel cells. Herein we report the synthesis of sulfur and nitrogen dual-doped, ordered mesoporous carbon (SN-OMCs), which shows outstanding ORR electrocatalytic properties. The material was synthesized from a surface-templating process of ferrocene within the channel walls of SBA-15 mesoporous silica by carbonization, followed by in situ heteroatomic doping with sulfur- and nitrogen-containing vapors. After etching away the metal and silica template, the resulting material features distinctive bimodal mesoporous carbon frameworks with high nitrogen Brunauer-Emmett-Teller specific surface area (of up to ?1100 m(2)/g) and uniform distribution of sulfur and nitrogen dopants. When employed as a noble-metal-free electrocatalyst for the ORR, such SN-OMC shows a remarkable electrocatalytic activity; improved durability and better resistance toward methanol crossover in oxygen reduction can be observed. More importantly, it performs a low onset voltage and an efficient nearly complete four-electron ORR process very similar to the observations in commercial 20 wt % Pt/C catalyst. In addition, we also found that the textural mesostructure of the catalyst has superseded the chemically bonded dopants to be the key factor in controlling the ORR performance. PMID:24245579

Xu, Jiaoxing; Zhao, Yi; Shen, Cai; Guan, Lunhui

2013-12-11

54

Phosphorylated mesoporous carbon as effective catalyst for the selective fructose dehydration to HMF  

SciTech Connect

Phosphorylated mesoporous carbons (PMCs) have been synthesized using an already reported one pot methodology. These materials have been applied as acidic catalysts in the dehydration of fructose to hydroxymethylfurfural (HMF). PMCs showed better selectivity to HMF compared to sulfonated carbon catalyst (SC) despite lower activity. The concentration of P-O groups correlates to the activity/selectivity of the catalysts; the higher the P-O concentration the higher the activity. However, the higher the P-O content the lower the selectivity to HMF. Indeed a lower concentration of the P-O groups (and even the acidic groups) minimized the degradation of HMF to levulinic acid and the formation of by-products, such as humines. Stability tests showed that these systems deactivate due to the formation of humines, water insoluble by-products derived from the dehydration of fructose, blocking the active site of the catalyst. Increasing the amount of P-O groups, higher amount of humines are formed; therefore carbons containing lower amount of phosphorylated groups, such as P/N-0.25, are less prone to deactivation. Keywords: Phosphorylated mesoporous carbons; fructose dehydration; HMF

Villa, Alberto [Universita di Milano, Italy; Schiavoni, Marco [University of Milan and INFN, Milano, Italy; Fulvio, Pasquale F [ORNL; Mahurin, Shannon Mark [ORNL; Dai, Sheng [ORNL; Mayes, Richard T [ORNL; Veith, Gabriel M [ORNL; Prati, Laura [Universita di Milano, Italy

2013-01-01

55

Adsorption of Pb(II) on mesoporous activated carbons fabricated from water hyacinth using H3PO4 activation: Adsorption capacity, kinetic and isotherm studies  

NASA Astrophysics Data System (ADS)

Activated carbons with high mesoporosity and abundant oxygen-containing functional groups were prepared from water hyacinth using H3PO4 activation (WHAC) to eliminate Pb(II) in water. Characterizations of the WHAC were performed using Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The BET analysis showed that WHAC possesses a high mesoporosity (93.9%) with a BET surface area of 423.6 m2/g. The presence of oxygen-containing functional groups including hydroxyl, carbonyl, carboxyl and phosphate groups renders the WHAC a favorable adsorbent for Pb(II) with the maximum monolayer capacity (qm) 118.8 mg/g. The adsorption behavior follows pseudo-first order kinetic and Langmuir isotherm. The desorption study demonstrated that the WHAC could be readily regenerated using 0.1 M HCl (pH = 1.0). The desorbed WHAC could be reused at least six times without significant adsorption capacity reduction. The adsorption process was spontaneous and endothermic with ?G (-0.27, -1.13, -3.02, -3.62, -5.54, and -9.31 kJ/mol) and ?H (38.72 kJ/mol). Under the optimized conditions, a small amount of the adsorbent (1.0 g/L) could remove as much as 90.1% of Pb(II) (50 mg/L) in 20 min at pH 6.0 and temperature of 298 K. Therefore, the WHAC has a great potential to be an economical and efficient adsorbent in the treatment of lead-contaminated water.

Huang, Yang; Li, Shunxing; Chen, Jianhua; Zhang, Xueliang; Chen, Yiping

2014-02-01

56

Photocatalytic activity of a hierarchically macro/mesoporous titania.  

PubMed

Light-harvesting macroporous channels have been successfully incorporated into a mesoporous TiO(2) framework to increase its photocatalytic activity. This bimodal porous material was characterized by X-ray diffractometry in both low-angle and wide-angle ranges, N(2) adsorption-desorption analysis, scanning and transmission electron microscopy, FT-IR, and diffuse reflectance spectroscopy. Ethylene photodegradation in gas-phase medium was employed as a probe reaction to evaluate the photocatalytic reactivity of the catalysts. The results reveal that sintering temperature significantly affects the structural stability and photocatalytic activity of titania. The catalyst which calcined at 350 degrees C possessed an intact macro/mesoporous structure and showed photocatalytic reactivity about 60% higher than that of commercial P25 titania. When the sample was calcined at 500 degrees C, the macroporous structure was retained but the mesoporous structure was partly destroyed. Further heating at temperatures above 600 degrees C destroyed both macro- and mesoporous structures, accompanied by a loss in photocatalytic activity. The high photocatalytic performance of the intact macro/mesoporous TiO(2) may be explained by the existence of macrochannels that increase photoabsorption efficiency and allow efficient diffusion of gaseous molecules. PMID:15752052

Wang, Xinchen; Yu, Jimmy C; Ho, Chunman; Hou, Yidong; Fu, Xianzhi

2005-03-15

57

Ion-selective electrodes with colloid-imprinted mesoporous carbon as solid contact.  

PubMed

A new type of solid-contact ion-selective electrode (SC-ISE) has been developed that uses colloid-imprinted mesoporous (CIM) carbon with 24 nm diameter, interconnected mesopores as the intermediate layer between a gold electrode and an ionophore-doped ISE membrane. For a demonstration, valinomycin was used as K(+) ionophore, and a good Nernstian response with a slope of 59.5 mV/decade in the range from 10(-5.2) to 10(-1.0) M was observed. The high purity, low content of redox-active surface functional groups and intrinsic hydrophobic characteristics of CIM carbon prepared from mesophase pitch lead to outstanding performance of these sensors, with excellent resistance to the formation of a water layer and no interference caused by light, O2, and CO2. When a redox couple is introduced as an internal reference species, calibration-free SC-ISEs can be made with a standard deviation of E° as low as 0.7 mV. Moreover, the interconnected mesopore structure of ISE membrane-infused CIM carbon facilitates both ion and electron conduction and provides a large interfacial area with good ion-to-electron transduction. Because of the large double layer capacitance of CIM carbon, CIM carbon-based SC-ISEs exhibit excellent potential stability, as shown by chronopotentiometry and continuous potentiometric measurements. The capacitance of these electrodes as determined by chronopotentiometry is 1.0 mF, and the emf drift over 70 h is as low as 1.3 ?V/h, making these electrodes the most stable SC-ISEs reported so far. PMID:24983327

Hu, Jinbo; Zou, Xu U; Stein, Andreas; Bühlmann, Philippe

2014-07-15

58

Enhanced capacitive deionization of graphene/mesoporous carbon composites.  

PubMed

Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are well retained and the composites display improved specific surface area and pore size distribution, as well as pore volume. Well dispersed GE nanosheets are deduced to be beneficial for enhanced electrical conductivity. The electrochemical performance of electrodes in an NaCl aqueous solution was characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrodes perform better on the capacitance values, conductive behaviour, rate performance and cyclic stability. The desalination capacity of the electrodes was evaluated by a batch mode electrosorptive experiment and the amount of adsorbed ions can reach 731 ?g g?¹ for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 ?g g?¹). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area. PMID:22836788

Zhang, Dengsong; Wen, Xiaoru; Shi, Liyi; Yan, Tingting; Zhang, Jianping

2012-09-01

59

Ordered mesoporous carbon electrodes for Li-O2 batteries.  

PubMed

Ordered mesoporous carbon (OMC) with highly ordered pore channels was applied as an oxygen-side electrode for a Li-O2 battery. To evaluate the effect of the pore channel size on battery performance, we employed OMCs possessing two different pore sizes (6 and 17 nm). When cycled at a current density of 200 mA g(-1)carbon, the OMC electrodes reduced polarization in the oxygen evolution reaction by 0.1 V compared to those consisting of conventional super P carbon electrode. X-ray diffraction and transmission electron microscopy of the discharged oxygen electrodes provided evidence for the formation of amorphous Li2O2, a product of the oxygen reduction reaction, inside the OMC pores rather than on the electrode surface as in the case of the super P electrode. The OMC electrodes were also effective at high current densities (500 mA g(-1)carbon and 1000 mA g(-1)carbon). PMID:24236914

Park, Jin-Bum; Lee, Jinwoo; Yoon, Chong Seung; Sun, Yang-Kook

2013-12-26

60

Hollow mesoporous carbon nitride nanosphere/three-dimensional graphene composite as high efficient electrocatalyst for oxygen reduction reaction  

NASA Astrophysics Data System (ADS)

Hollow mesoporous carbon nitride nanosphere (HMCN) is firstly prepared via an etching route using hollow mesoporous silica as a sacrificial template. The as-obtained HMCN is a uniform spherical particle with a diameter of ?300 nm?and possesses a high specific surface area up to 439 m2 g-1. Hollow mesoporous carbon nitride nanosphere/three-dimensional (3D) graphene composite (HMCN-G) is subsequently fabricated via a hydrothermal treatment of HMCN with graphene oxide. As an electrocatalyst for oxygen reduction reaction (ORR), the HMCN-G shows significantly enhanced electrocatalytic activity compared to bulk graphitic carbon nitride (g-C3N4) and HMCN in terms of the electron-transfer number, current density and onset potential. Increased density of catalytically active sites and improved accessibility to electrolyte enabled by the hollow and mesoporous architecture of HMCN, and high conductivity induced from graphene are considered to contribute to the remarkable electrocatalytic performance of the HMCN-G. Furthermore, HMCN-G exhibits superior methanol tolerance to Pt/C catalyst, suggesting that it is a promising metal-free electrocatalyst for polymer electrolyte membrane fuel cell (PEMFC).

Qin, Yong; Li, Juan; Yuan, Jie; Kong, Yong; Tao, Yongxin; Lin, Furong; Li, Shan

2014-12-01

61

Synthesis and characterization of gyroidal mesoporous carbons and carbon monoliths with tunable ultralarge pore size.  

PubMed

Ordered mesoporous carbons with high pore accessibility are of great interest as electrodes in energy conversion and storage applications due to their high electric and thermal conductivity, chemical inertness, and low density. The metal- and halogen-free synthesis of gyroidal bicontinuous mesoporous carbon materials with uniform and tunable pore sizes through bottom-up self-assembly of block copolymers thus poses an interesting challenge. Four double gyroidal mesoporous carbons with pore sizes of 12, 15, 20, and 39 nm were synthesized using poly(isoprene)-block-poly(styrene)-block-poly(ethylene oxide) (ISO) as structure-directing triblock terpolymer and phenol-formaldehyde resols as carbon precursors. The highly ordered materials were thermally stable to at least 1600 °C with pore volumes of up to 1.56 cm(3) g(-1). Treatment at this temperature induced a high degree of sp(2)-hybridization and low microporosity. Increasing the resols/ISO ratio led to hexagonally packed cylinders with lower porosity. A single gyroid carbon network with high porosity of 80 vol % was obtained using a similar synthesis strategy. Furthermore, we present a method to fabricate monolithic materials of the gyroidal carbons with macroscopic shape and thickness control that exhibit an open and structured surface with gyroidal features. The gyroidal materials are ideally suited as electrode materials in fuel cells, batteries, and supercapacitors as their high, three-dimensionally connected porosity is expected to allow for good fuel or electrolyte accessibility and to prevent total pore blockage. PMID:24328285

Werner, Jörg G; Hoheisel, Tobias N; Wiesner, Ulrich

2014-01-28

62

Bicontinuous gyroidal mesoporous carbon matrix for facilitating protein electrochemical and bioelectrocatalytic performances.  

PubMed

A strategy of protein-entrapment in bicontinuous gyroidal mesoporous carbon (BGMC) nanocomposite films is described. Herein, the quasi-reversible electron transfer of redox proteins (such as glucose oxidase and myoglobin) is probed and the associated biocatalytic activity is revealed. The apparent heterogeneous electron transfer rate constant of the immobilized glucose oxidase is up to 9.4 s(-1), much larger than those in carbon nanotubes and some conventional mesoporous carbons. The BGMC based glucose biosensor enables the determination of glucose at a potential of 0.6 V (vs. SCE). Its detection limit is 1.0×10(-5) M (signal-to-noise ratio, S/N=3), the linear response is up to 7.49 mM and the detection sensitivity is 52.5 nA mM(-1) Furthermore, a series of BGMCs with different pore sizes is designed and synthesized using sucrose or phenol formaldehyde resin to study the influences of pore sizes and carbon sources on the immobilization of redox proteins and on the heterogeneous electron transfer. PMID:21238745

You, Chunping; Yan, Xuewu; Kong, Jilie; Zhao, Dongyuan; Liu, Baohong

2011-02-15

63

Synthesis, characterization and magnetic performance of Co-incorporated ordered mesoporous carbons  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer A facile one-pot aqueous self-assembly strategy for the synthesis Co-incorporated ordered mesoporous carbons (Co-OMCs). Black-Right-Pointing-Pointer Co-OMCs exhibit typical ferromagnetic characteristics. Black-Right-Pointing-Pointer Saturation magnetization strength can be easily adjusted by changing the content of cobalt. Black-Right-Pointing-Pointer Carbonization temperatures have significant effects on the structure and magnetic properties of Co-OMCs. -- Abstract: Co-incorporated ordered mesoporous carbon (Co-OMC) with magnetic frameworks has been synthesized via a one-pot self-assembly strategy. The effects of cobalt loading on carbon matrix, adsorption properties and magnetic properties of the resultant mesostructured cobalt/carbon composites were investigated by nitrogen sorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TG) and magnetometer measurements. The results show that the mesoporous composites with a high cobalt content (such as 18.0 wt%) possess an ordered and uniform mesoporous structure (5.3 nm), high surface areas (up to 687 m{sup 2}/g) and high pore volumes (up to 0.54 cm{sup 3}/g). Cobalt nanoparticles of size 4-9 nm are confined inside the mesopores or walls of the mesoporous carbon. These materials exhibit typical ferromagnetic characteristics. The saturation magnetization strength can be easily adjusted by changing the content of cobalt. The carbonization temperatures have significant effects on the structure and magnetic properties of Co-OMC also.

Liu, Zhi, E-mail: zhiliu@lnnu.edu.cn [Institute of Chemistry for Functionalized Materials, Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China)] [Institute of Chemistry for Functionalized Materials, Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China); Song, Yan; Yang, Yuan; Mi, Junhua; Deng, Liping [Institute of Chemistry for Functionalized Materials, Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China)] [Institute of Chemistry for Functionalized Materials, Faculty of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029 (China)

2012-02-15

64

A novel polyaniline\\/mesoporous carbon nano-composite electrode for asymmetric supercapacitor  

Microsoft Academic Search

A novel nano-composite of polyaniline\\/mesoporous carbon (PANI\\/CMK-3) was prepared with mesoporous carbon (CMK-3) serving as the support. Electrochemical asymmetric capacitors have been successfully designed by using PANI\\/CMK-3 composite and CMK-3 as positive and negative electrode, respectively. The results showed that the discharge capacity of the asymmetric capacitor could reach 87.4F\\/g under the current density of 5mA\\/cm2 and cell voltage of

Jian Jun Cai; Ling Bin Kong; Jing Zhang; Yong Chun Luo; Long Kang

2010-01-01

65

Evolution of the complex surface chemistry in mesoporous carbons obtained from polyaramide precursors  

NASA Astrophysics Data System (ADS)

Chemical evolution of micro/mesoporous ordered carbons containing nitrogen, oxygen and phosphorus surface functionalities was investigated by XPS. Nanocasting was selected as synthetic route: SBA-15 mesoporous silica was the solid template, 3-aminobenzoic acid was used as carbon, nitrogen and oxygen precursor, and phosphoric acid was selected to achieve doping with phosphorus. The evolution of the surface chemistry as a function of phosphoric acid concentration and carbonization temperature was studied, and carbons with a wide range of type and number of surface functional groups were identified. Thus, we show an easy way to successfully design ordered carbons exhibiting a specific surface composition by selecting certain experimental conditions.

Sánchez-Sánchez, A.; Suárez-García, F.; Martínez-Alonso, A.; Tascón, J. M. D.

2014-04-01

66

Enhanced capacitive deionization of graphene/mesoporous carbon composites  

NASA Astrophysics Data System (ADS)

Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are well retained and the composites display improved specific surface area and pore size distribution, as well as pore volume. Well dispersed GE nanosheets are deduced to be beneficial for enhanced electrical conductivity. The electrochemical performance of electrodes in an NaCl aqueous solution was characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrodes perform better on the capacitance values, conductive behaviour, rate performance and cyclic stability. The desalination capacity of the electrodes was evaluated by a batch mode electrosorptive experiment and the amount of adsorbed ions can reach 731 ?g g-1 for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 ?g g-1). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area.Capacitive deionization (CDI) with low-energy consumption and no secondary waste is emerging as a novel desalination technology. Graphene/mesoporous carbon (GE/MC) composites have been prepared via a direct triblock-copolymer-templating method and used as CDI electrodes for the first time. The influences of GE content on the textural properties and electrochemical performance were studied. The transmission electron microscopy and nitrogen adsorption-desorption analysis indicate that mesoporous structures are well retained and the composites display improved specific surface area and pore size distribution, as well as pore volume. Well dispersed GE nanosheets are deduced to be beneficial for enhanced electrical conductivity. The electrochemical performance of electrodes in an NaCl aqueous solution was characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements. The composite electrodes perform better on the capacitance values, conductive behaviour, rate performance and cyclic stability. The desalination capacity of the electrodes was evaluated by a batch mode electrosorptive experiment and the amount of adsorbed ions can reach 731 ?g g-1 for the GE/MC composite electrode with a GE content of 5 wt%, which is much higher than that of MC alone (590 ?g g-1). The enhanced CDI performance of the composite electrodes can be attributed to the better conductive behaviour and higher specific surface area. Electronic supplementary information (ESI) available: Experimental details. XRD patterns, TEM image and nitrogen adsorption-desorption isotherms of the samples. Cyclic voltammograms and galvanostatic charge-discharge curves of the GE/MC electrodes. See DOI: 10.1039/c2nr31154b

Zhang, Dengsong; Wen, Xiaoru; Shi, Liyi; Yan, Tingting; Zhang, Jianping

2012-08-01

67

Soybean-derived mesoporous carbon as an effective catalyst support for electrooxidation of methanol  

NASA Astrophysics Data System (ADS)

In this work, a low cost and nitrogen-containing carbon (CS) with mesoporous structure and high surface area is synthesized by carbonizing soybean. It is found that the prepared CS has excellent textural properties such as high specific surface areas and large pore diameters. TEM images show that the Pt nano-sized dendrites are well formed on the surface of CS. Compared to Pt supported on Vulcan carbon XC-72, electrochemical results show that Pt supported on CS possesses a higher electrocatalytic activity and better durability in methanol oxidation reaction, which are mainly attributed to the support effect of CS resulting in the unique morphology of Pt particles and high content of Pt(0). These results indicate that CS has great potential as a high-performance catalyst support for fuel cell electrocatalysis.

Zhou, Tianbao; Wang, Hui; Ji, Shan; Linkov, Vladimir; Wang, Rongfang

2014-02-01

68

Transition metal ion capture using functional mesoporous carbon made with 1,10-phenanthroline?  

PubMed Central

Functional mesoporous carbon has been built using 1,10-phenanthroline as the fundamental building block, resulting in a nanoporous, high surface area sorbent capable of selectively binding transition metal ions. This material had a specific surface area of 870 m2/g, an average pore size of about 30 Å, and contained as much as 8.2 wt% N. Under acidic conditions, where the 1,10-phenanthroline ligand is protonated, this material was found to be an effective anion exchange material for transition metal anions like PdCl42- and H2VO41-. 1,10-Phenanthroline functionalized mesoporous carbon (“Phen-FMC”) was found to have a high affinity for Cu(II), even down to a pH of 1. At pHs above 5, Phen-FMC was found to bind a variety of transition metal cations (e.g. Co(II), Ni(II), Zn(II), etc.) from filtered ground water, river water and seawater. Phen-FMC displayed rapid sorption kinetics with Co(II) in filtered river water, reaching equilibrium in less than an hour, and easily lowering the [Co(II)] to sub-ppb levels. Phen-FMC was found to be more effective for transition metal ion capture than ion-exchange resin or activated carbon. PMID:23762013

Chouyyok, Wilaiwan; Yantasee, Wassana; Shin, Yongsoon; Grudzien, Rafal M.; Fryxell, Glen E.

2012-01-01

69

A mesoporous carbon-supported Pt nanocatalyst for the conversion of lignocellulose to sugar alcohols.  

PubMed

The conversion of lignocellulose is a crucial topic in the renewable and sustainable chemical industry. However, cellulose from lignocellulose is not soluble in polar solvents, and is, therefore, difficult to convert into value-added chemicals. A strategy to overcome this drawback is the use of mesoporous carbon, which enhances the affinity between the cellulose and the catalyst through its abundant functional groups and large uniform pores. Herein, we report on the preparation of a Pt catalyst supported on a type of 3D mesoporous carbon inspired by Echinometra mathae (Pt/CNE) to enhance the interaction between the catalyst and a nonsoluble reactant. In the hydrolytic hydrogenation of cellulose, the abundant oxygen groups of CNE facilitated the access of cellulose to the surface of the catalyst, and the open pore structure permits cello-oligomers to effectively diffuse to the active sites inside the pore. The highly dispersed Pt performed dual roles: hydrolysis by in?situ generating protons from H2 or water as well as effective hydrogenation. The use of the Pt/CNE catalyst resulted in an approximately 80?% yield of hexitol, the best performance reported to date. In direct conversion of hardwood powder, the Pt/CNE shows good performance in the production of sugar alcohols (23?% yield). We expect that the open-structured 3D carbon will be widely applied to the conversion of various lignocellulosic materials. PMID:24227502

Park, Dae Sung; Yun, Danim; Kim, Tae Yong; Baek, Jayeon; Yun, Yang Sik; Yi, Jongheop

2013-12-01

70

Metal-nitrogen doping of mesoporous carbon/graphene nanosheets by self-templating for oxygen reduction electrocatalysts.  

PubMed

We demonstrate a general and efficient self-templating strategy towards transition metal-nitrogen containing mesoporous carbon/graphene nanosheets with a unique two-dimensional (2D) morphology and tunable mesoscale porosity. Owing to the well-defined 2D morphology, nanometer-scale thickness, high specific surface area, and the simultaneous doping of the metal-nitrogen compounds, the as-prepared catalysts exhibits excellent electrocatalytic activity and stability towards the oxygen reduction reaction (ORR) in both alkaline and acidic media. More importantly, such a self-templating approach towards two-dimensional porous carbon hybrids with diverse metal-nitrogen doping opens up new avenues to mesoporous heteroatom-doped carbon materials as electrochemical catalysts for oxygen reduction and hydrogen evolution, with promising applications in fuel cell and battery technologies. PMID:25213723

Li, Shuang; Wu, Dongqing; Liang, Haiwei; Wang, Jinzuan; Zhuang, Xiaodong; Mai, Yiyong; Su, Yuezeng; Feng, Xinliang

2014-11-01

71

Neutron imaging of ion transport in mesoporous carbon materials.  

PubMed

Neutron imaging is presented as a tool for quantifying the diffusion of ions inside porous materials, such as carbon electrodes used in the desalination process via capacitive deionization and in electrochemical energy-storage devices. Monolithic mesoporous carbon electrodes of ?10 nm pore size were synthesized based on a soft-template method. The electrodes were used with an aqueous solution of gadolinium nitrate in an electrochemical flow-through cell designed for neutron imaging studies. Sequences of neutron images were obtained under various conditions of applied potential between the electrodes. The images revealed information on the direction and magnitude of ion transport within the electrodes. From the time-dependent concentration profiles inside the electrodes, the average value of the effective diffusion coefficient for gadolinium ions was estimated to be 2.09 ± 0.17 × 10(-11) m(2) s(-1) at 0 V and 1.42 ± 0.06 × 10(-10) m(2) s(-1) at 1.2 V. The values of the effective diffusion coefficient obtained from neutron imaging experiments can be used to evaluate model predictions of the ion transport rate in capacitive deionization and electrochemical energy-storage devices. PMID:23756558

Sharma, Ketki; Bilheux, Hassina Z; Walker, Lakeisha M H; Voisin, Sophie; Mayes, Richard T; Kiggans, Jim O; Yiacoumi, Sotira; DePaoli, David W; Dai, Sheng; Tsouris, Costas

2013-07-28

72

Adsorption of Carbon Dioxide from Gas Streams via Mesoporous Spherical-Silica Particles  

Microsoft Academic Search

A relatively new mesoporous silica sorbent for environmental protection applications (i.e., mesoporous spherical-silica particles [MSPs]), was modified by N-[3-(trimethoxysilyl)propyl]ethylenediamine (EDA) solution and was tested for its potential in the separation of carbon dioxide (CO2) from flue gas. The CO2 adsorption capacity of MSP and MSP(EDA) increased with temperature from 20 to 60 °C but decreased with temperature from 60 to

Chungsying Lu; Hsunling Bai; Fengsheng Su; Wenfa Chen; Jyh Feng Hwang; Hsiu-Hsia Lee; Walter Nakaema; Wellington Jesus; Maria Jorge; Rauda Mariani; Klara Slezakova; Dionísia Castro; Maria Pereira; Simone Morais; Cristina Delerue-Matos; Maria Alvim-Ferraz; Catherine Barton; Charles Zarzecki; Mark Russell; Marjaleena Aatamila; Pia Verkasalo; Maarit Korhonen; Marja Viluksela; Kari Pasanen; Pekka Tiittanen; Aino Nevalainen; Li Rong; Peter Nielsen; Guoqiang Zhang; Yi-Ming Kuo; Juu-En Chang; Kun-Yu Chang; Chih-C. Chao; Yeu-Juin Tuan; Guo-Ping Chang-Chien; Yongping Li; Guohe Huang; Arhontoula Chatzilazarou; Evangelos Katsoyannos; Olga Gortzi; Stavros Lalas; Yiannis Paraskevopoulos; Euthalia Dourtoglou; John Tsaknis; Tarek Abichou; Jeremy Clark; Sze Tan; Jeffery Chanton; Gary Hater; Roger Green; Doug Goldsmith; Morton Barlaz; Nathan Swan; Gang Sun; Huiqing Guo; Jonathan Peterson; Zhengmin Qian; Hung-Mo Lin; Walter Stewart; Nirav Shah; Linli Kong; Fen Xu; Denjin Zhou; Zhicao Zhu; Qingci He; Shengwen Liang; Weiqing Chen; Judith Chow; John Watson; Douglas Lowenthal; Lung-Wen Chen; Nehzat Motallebi

2010-01-01

73

Utilization of environmentally benign dicyandiamide as a precursor for the synthesis of ordered mesoporous carbon nitride and its application in base-catalyzed reactions.  

PubMed

Assisted by a new dissolution procedure, dicyandiamide (DCDA), an environmentally benign and cheap precursor, has been employed for the synthesis of mesoporous carbon nitride (CN) materials through a nanocasting approach. The synthesized mesoporous materials possessed high specific surface areas (269-715?m(2) ?g(-1) ) with narrow pore-size distributions (about 5?nm) and faithfully replicated the mesostructures of the SBA-15 and FDU-12 templates. Several characterization techniques, including XRD, SAXS, TEM, Raman and FTIR spectroscopy, XPS, and CO2 -TPD, were used to analyze the physicochemical properties of these materials and the results showed that the mesoporous CND materials had graphitic-like structures and consisted of CN heterocycles, as well as amino groups. In a series of Knoevenagel condensation reactions, as exemplified by the reaction of various aldehydes and nitriles, these mesoporous CND materials demonstrated high and stable catalytic activities, owing to an abundance of basic sites. PMID:25204431

Xu, Jie; Chen, Ting; Jiang, Quan; Li, Yong-Xin

2014-11-01

74

Bromate removal from aqueous solutions by ordered mesoporous carbon.  

PubMed

We investigated the feasibility of using ordered mesoporous carbon (OMC) for bromate removal from water. Batch experiments were performed to study the influence of various experimental parameters such as the effect of contact time, adsorbent dosage, initial bromate concentration, temperature, pH and effect of competing anions on bromate removal by OMC. The adsorption kinetics indicates that the uptake rate ofbromate was rapid at the beginning: 85% adsorption was completed in 1 h and equilibrium was achieved within 3 h. The sorption process was well described with pseudo-second-order kinetics. The maximum adsorption capacity of OMC for bromate removal was 17.6 mg g(-1) at 298 K. The adsorption data fit the Freundlich model well. The amount of bromate removed was found to be proportional to the influent bromate concentration. The effects of competing anions and solution pH (3-11) were negligible. These limited data suggest that OMC can be effectively utilized for bromate removal from drinking water. PMID:24645482

Xu, Chunhua; Wang, Xiaohong; Shi, Xiaolei; Lin, Sheng; Zhu, Liujia; Che, Yaming

2014-01-01

75

Facile synthesis of hydrophilic multi-colour and upconversion photoluminescent mesoporous carbon nanoparticles for bioapplications.  

PubMed

Hydrophilic mesoporous carbon nanoparticles (MCNs) have been synthesized via an extremely facile precursor carbonization-in-hot solvent route. The synthesized MCNs show well-defined particle and pore size distribution at around 100 nm and 2.7 nm, respectively, and multicolor and upconversion photoluminescence, which endow the MCNs with multicolor/upconversion bioimaging and drug delivery properties. PMID:25371274

Kong, Qinglu; Zhang, Lingxia; Liu, Jianan; Wu, Meiying; Chen, Yu; Feng, Jingwei; Shi, Jianlin

2014-12-25

76

Fabrication and characterization of carbon nanofiber@mesoporous carbon core-shell composite for the Li-air battery  

NASA Astrophysics Data System (ADS)

In this study, we successfully design and synthesize the mesoporous carbon coated carbon nanofibers (CNF@mesoCs) for the Li-air battery. The composites are fabricated via electrospinning technique and nanocasting strategy. After mesoporous carbon coating process, the composites have retained their original one-dimensional structure as pristine carbon nanofibers. Every nanofiber entangles with each other to form a three-dimensional cross-linked web structure. Because of the mesoporous carbon coating on carbon nanofibers, the surface area increases from 708 m2 g-1 to 2194 m2 g-1. We confirm that the mesoporous carbon coated on carbon nanofibers is well-graphitized by analysis of Raman spectra. The graphitized surface of CNF@mesoCs (4.638 S cm-1) is believed to result in their higher electrical conductivity than that of pristine carbon nanofibers (3.0759 S cm-1). Without employment of any binders and metal foams, the cathode of CNF@mesoCs exhibits high discharge capacity of 4000 mA h g-1, which is much higher than that from pristine carbon nanofibers (2750 mA h g-1). This work demonstrates that the fabricated CNF@mesoCs structures have a great potential to be employed as light-weight and efficient electrode for energy storage and conversion devices.

Song, Myeong Jun; Shin, Moo Whan

2014-11-01

77

Self-Assembly Synthesis and Functionalization of Mesoporous Carbon Materials for Energy-Related Applications  

SciTech Connect

Self-Assembly Synthesis and Functionalization of Mesoporous Carbon Materials for Energy-Related Applications Sheng Dai Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6201 Porous carbon materials are ubiquitous in separation, catalysis, and energy storage/conversion. Well-defined mesoporous carbon materials are essential for a number of the aforementioned applications. Ordered porous carbon materials have previously been synthesized using colloidal crystals and presynthesized mesoporous silicas as hard templates. The mesostructures of these carbon materials are connected via ultrathin carbon filaments and can readily collapse under high-temperature conditions. Furthermore, these hard-template methodologies are extremely difficult to adapt to the fabrication of large-scale ordered nanoporous films or monoliths with controlled pore orientations. More recently, my research group at the Oak Ridge National Laboratory and several others around the world have developed alternative methods for synthesis of highly ordered mesoporous carbons via self-assembly. Unlike the mesoporous carbons synthesized via hard-template methods, these mesoporous carbons are highly stable and can be graphitized at high temperature (>2800?C) without significant loss of mesopores. The surface properties of these materials can be further tailored via surface functionalization. This seminar will provide an overview and perspective of the mesoporous carbon materials derived from soft-template synthesis and surface functionalization and their fascinating applications in catalysis, separation, and energy storage devices. Dr. Sheng Dai got his B.S. and M.S. degrees from Zhejiang University in 1984 and 1986, respectively. He subsequently obtained a PhD degree from the University of Tennessee, Knoxville in 1990. He is currently a Senior Staff Scientist and Group Leader of Nanomaterials Group and Center for Nanophase Materials Science of Oak Ridge National Laboratory and is also affiliated with the University of Tennessee as an adjunct professor. He is a co-author of more than 200 publications. His research interests include porous materials and their functionalization, new ionic liquids for chemical separation and materials synthesis, sol-gel synthesis and molecular imprinting of inorganic materials, and catalysis by nanomaterials especially gold nanocatalysts.

Dai, Sheng [ORNL] [ORNL

2009-01-01

78

Towards Vaporized Molecular Discrimination: A Quartz Crystal Microbalance (QCM) Sensor System Using Cobalt-Containing Mesoporous Graphitic Carbon.  

PubMed

A recent study on nanoporous carbon based materials (J. Am. Chem. Soc.- 2012, 134, 2864) showed that the presence of abundant graphitized sp(2) carbon species in the frameworks led to higher affinity for aromatic hydrocarbons than their aliphatic analogues. Herein, improved understanding of the sensitive and selective detection of aromatic substances by using mesoporous carbon (MPC)-based materials, combined with a quartz crystal microbalance (QCM) sensor system, was obtained. MPCs were synthesized by direct carbonization of mesoporous polymers prepared from resol through a soft templating approach with Pluronic F127. The carbon-based frameworks can be graphitized through the addition of a cobalt source to the precursor solution, according to the catalytic activity of the cobalt nanoparticles formed during the carbonization process. From the Raman data, the degree of the graphitization was clearly increased by increasing the cobalt content and elevating the carbonization temperature. From a QCM study, it was proved that the highly graphitized MPCs exhibited a higher affinity for aromatic hydrocarbons than their aliphatic analogues. By increasing the degree of graphitization in the carbon-based pore walls, the MPCs showed both larger adsorption uptake and faster sensor response towards toxic benzene and toluene vapors. PMID:25213201

Tang, Jing; Torad, Nagy L; Salunkhe, Rahul R; Yoon, Jang-Hee; Al Hossain, Md Shahriar; Dou, Shi Xue; Kim, Jung Ho; Kimura, Tatsuo; Yamauchi, Yusuke

2014-11-01

79

Fabrication of mesoporous and high specific surface area lanthanum carbide–carbon nanotube composites  

Microsoft Academic Search

Mesoporous lanthanum carbide–carbon nanotube composites were produced by means of carbothermal reaction of lanthanum oxide, graphite and multi-walled carbon nanotube mixtures under high vacuum. Residual gas analysis revealed the higher reactivity of lanthanum oxide towards carbon nanotubes compared to graphite. After sintering, the composites revealed a specific surface area increasing with the amount of carbon nanotubes introduced. The meso-porosity of

L. Biasetto; S. Carturan; G. Maggioni; P. Zanonato; P. Di Bernardo; P. Colombo; A. Andrighetto; G. Prete

2009-01-01

80

Hierarchical mesoporous/microporous carbon with graphitized frameworks for high-performance lithium-ion batteries  

NASA Astrophysics Data System (ADS)

A hierarchical meso-/micro-porous graphitized carbon with uniform mesopores and ordered micropores, graphitized frameworks, and extra-high surface area of ˜2200 m2/g, was successfully synthesized through a simple one-step chemical vapor deposition process. The commercial mesoporous zeolite Y was utilized as a meso-/ micro-porous template, and the small-molecule methane was employed as a carbon precursor. The as-prepared hierarchical meso-/micro-porous carbons have homogeneously distributed mesopores as a host for electrolyte, which facilitate Li+ ions transport to the large-area micropores, resulting a high reversible lithium ion storage of 1000 mA h/g and a high columbic efficiency of 65% at the first cycle.

Lv, Yingying; Wu, Zhangxiong; Fang, Yin; Qian, Xufang; Asiri, Abdullah M.; Tu, Bo; Zhao, Dongyuan

2014-11-01

81

A facile method for fabricating TiO2@mesoporous carbon and three-layered nanocomposites  

NASA Astrophysics Data System (ADS)

Herein, we report a new and facile method for fabricating TiO2@mesoporous carbon hybrid materials. Uniform polydopamine (PDA) layers were coated onto the surface of titanate nanotubes (TNTs) and TiO2 nanorods (TNDs) through the spontaneous adhesion and self-polymerization of dopamine during the dipping process. Core-shell mesoporous carbon nanotubes with TiO2 nanorods or nanoparticles encapsulated inside (TiO2@MC) were then obtained by transforming PDA layers into carbonaceous ones through calcination in nitrogen at 800?°C. The thickness of the mesoporous carbon layers is tens of nanometers and can be controlled by adjusting the coated PDA layers through the self-polymerization reaction time. In addition, three-layered nanocomposites of TiO2@MC@MO (MO, metal oxide) can be readily prepared by utilizing PDA layers in TNTs@PDA or TNDs@PDA to adsorb the metal ions, followed by the calcination process.

Liu, Yong; Jin, Haibao; Zhu, Shenmin; Liu, Yunchun; Long, Mingce; Zhou, Yongfeng; Yan, Deyue

2012-08-01

82

Hierarchical nanostructured spherical carbon with hollow core\\/mesoporous shell as a highly efficient counter electrode in CdSe quantum-dot-sensitized solar cells  

Microsoft Academic Search

Hierarchical nanostructured spherical carbon with hollow core\\/mesoporous shell (HCMS) was explored as a counter electrode in CdSe quantum-dot-sensitized solar cells. Compared with conventional Pt electrodes and commercially available activated carbon, the HCMS carbon counter electrode exhibits a much larger fill factor due to the considerably decreased charge transfer resistance at the interface of the counter electrode\\/polysulfide electrolyte. Furthermore, a solar

Sheng-Qiang Fan; Baizeng Fang; Jung Ho Kim; Jeum-Jong Kim; Jong-Sung Yu; Jaejung Ko

2010-01-01

83

Free-standing mesoporous carbon thin films with highly ordered pore architectures for nanodevices.  

PubMed

We report for the first time the synthesis of free-standing mesoporous carbon films with highly ordered pore architecture by a simple coating-etching approach, which have an intact morphology with variable sizes as large as several square centimeters and a controllable thickness of 90 nm to ?3 ?m. The mesoporous carbon films were first synthesized by coating a resol precursors/Pluronic copolymer solution on a preoxidized silicon wafer and forming highly ordered polymeric mesostructures based on organic-organic self-assembly, followed by carbonizing at 600 °C and finally etching of the native oxide layer between the carbon film and the silicon substrate. The mesostructure of this free-standing carbon film is confirmed to be an ordered face-centered orthorhombic Fmmm structure, distorted from the (110) oriented body-centered cubic Im3?m symmetry. The mesoporosity of the carbon films has been evaluated by nitrogen sorption, which shows a high specific BET surface area of 700 m(2)/g and large uniform mesopores of ?4.3 nm. Both mesostructures and pore sizes can be tuned by changing the block copolymer templates or the ratio of resol to template. These free-standing mesoporous carbon films with cracking-free uniform morphology can be transferred or bent on different surfaces, especially with the aid of the soft polymer layer transfer technique, thus allowing for a variety of potential applications in electrochemistry and biomolecule separation. As a proof of concept, an electrochemical supercapacitor device directly made by the mesoporous carbon thin films shows a capacitance of 136 F/g at 0.5 A/g. Moreover, a nanofilter based on the carbon films has shown an excellent size-selective filtration of cytochrome c and bovine serum albumin. PMID:21854032

Feng, Dan; Lv, Yingying; Wu, Zhangxiong; Dou, Yuqian; Han, Lu; Sun, Zhenkun; Xia, Yongyao; Zheng, Gengfeng; Zhao, Dongyuan

2011-09-28

84

Polymeric carbon nitride/mesoporous silica composites as catalyst support for Au and Pt nanoparticles.  

PubMed

Small and homogeneously dispersed Au and Pt nanoparticles (NPs) were prepared on polymeric carbon nitride (CNx )/mesoporous silica (SBA-15) composites, which were synthesized by thermal polycondensation of dicyandiamide-impregnated preformed SBA-15. By changing the condensation temperature, the degree of condensation and the loading of CNx can be controlled to give adjustable particle sizes of the Pt and Au NPs subsequently formed on the composites. In contrast to the pure SBA-15 support, coating of SBA-15 with polymeric CNx resulted in much smaller and better-dispersed metal NPs. Furthermore, under catalytic conditions the CNx coating helps to stabilize the metal NPs. However, metal NPs on CNx /SBA-15 can show very different catalytic behaviors in, for example, the CO oxidation reaction. Whereas the Pt NPs already show full CO conversion at 160?°C, the catalytic activity of Au NPs seems to be inhibited by the CNx support. PMID:24497094

Xiao, Ping; Zhao, Yanxi; Wang, Tao; Zhan, Yingying; Wang, Huihu; Li, Jinlin; Thomas, Arne; Zhu, Junjiang

2014-03-01

85

Properties of a three-dimensionally ordered macro-mesoporous carbon-doped TiO2 composite catalyst  

NASA Astrophysics Data System (ADS)

This study aimed to develop an effective, environmentally benign composite catalyst composed of carbon materials and titanium dioxide (TiO2). Carbon-doped titanium dioxide (C-TiO2) was prepared by coating TiO2 onto macro-mesoporous carbon (MMC). The structure, morphology and surface chemistry states of the C-TiO2 were characterized by XRD, TEM, XPS, UV-vis and FTIR. The photocatalytic activity of C-TiO2 was evaluated based on the decomposition of an aqueous methyl orange solution in visible light. C-TiO2 significantly improved photocatalytic activity. A possible mechanism for the improvement of the photocatalytic activity of C-TiO2 in visible light was proposed. The results of the analysis suggested that MMC played key roles as the support, absorbent, location of photo-generated electron transfer, and carbon-doping source during methyl orange photodegradation.

Sui, Wubin; Zheng, Jingtang; Pittman, Charles U.; Bensalah, Nasr; Wu, Mingbo; Zhao, Yucui

2014-11-01

86

Mesoporous carbon amperometric glucose sensors using inexpensive, commercial methacrylate-based binders.  

PubMed

Two ordered, soft-templated mesoporous carbon powders with cubic and hexagonal framework structure and four different commercial, low cost methacrylate-based polymer binders with widely varying physical properties are investigated as screen printed electrodes for glucose sensors using glucose oxidase and ferricyanide as the mediator. Both the chemistry and concentration of the binder in the electrode formulation can significantly impact the performance. Poly(hydroxybutyl methacrylate) as the binder provides hydrophilicity to enable transport of species in the aqueous phase to the carbon surface, but yet is sufficiently hydrophobic to provide mechanical robustness to the sensor. The current from the mesoporous carbon electrodes can be more than an order of magnitude greater than for a commercial printed carbon electrode (Zensor) with improved sensitivity for model glucose solutions. Even when applying these sensors to rabbit whole blood, the performance of these glucose sensors compares favorably to a standard commercial glucose meter with the lower detection limit of the mesoporous electrode being approximately 20mgdL(-1) despite the lack of a separation membrane to prevent non-specific events; these results suggest that the small pore sizes and high surface areas associated with ordered mesoporous carbons may effectively decrease some non-specific inferences for electrochemical sensing. PMID:22790696

Dai, Mingzhi; Maxwell, Stephanie; Vogt, Bryan D; La Belle, Jeffrey T

2012-08-13

87

A novel mesoporous carbon@silicon-silica nanostructure for high-performance Li-ion battery anodes.  

PubMed

A novel hierarchical nanostructure with graphite-like carbon and small Si nanocrystals, respectively, encapsulated in the mesopores and embedded in the silica framework of mesoporous silica nanoparticles has been facilely constructed and used as an anode for Li-ion batteries, which exhibits high specific storage capacity and extraordinarily high cycling stability. PMID:25264582

He, Qianjun; Xu, Chaohe; Luo, Jianqiang; Wu, Wei; Shi, Jianlin

2014-10-16

88

Effect of diffuse layer and pore shapes in mesoporous carbon supercapacitors  

SciTech Connect

In the spirit of the theoretical evolution from the Helmholtz model to the Gouy Chapman Stern model for electric double-layer capacitors, we explored the effect of a diffuse layer on the capacitance of mesoporous carbon supercapacitors by solving the Poisson Boltzmann (PB) equation in mesopores of diameters from 2 to 20 nm. To evaluate the effect of pore shape, both slit and cylindrical pores were considered. We found that the diffuse layer does not affect the capacitance significantly. For slit pores, the area-normalized capacitance is nearly independent of pore size, which is not experimentally observed for template carbons. In comparison, for cylindrical pores, PB simulations produce a trend of slightly increasing area-normalized capacitance with pore size, similar to that depicted by the electric double-cylinder capacitor model proposed earlier. These results indicate that it is appropriate to approximate the pore shape of mesoporous carbons as being cylindrical and the electric double-cylinder capacitor model should be used for mesoporous carbons as a replacement of the traditional Helmholtz model.

Huang, Jingsong [ORNL; Sumpter, Bobby G [ORNL; Meunier, Vincent [ORNL; Qiao, Rui [ORNL

2010-01-01

89

Electrochemical properties of boron-doped ordered mesoporous carbon as electrocatalyst and Pt catalyst support.  

PubMed

The electrochemical properties of boron-doped ordered mesoporous carbon (BOMC) as an electrode material and Pt catalyst support were investigated. The BOMC was synthesized and its structure was examined by transmission electron microscopy (TEM), scanning electron microscopy, nitrogen adsorption-desorption, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). More defective sites were introduced into OMC by the doping of boron. Six electroactive compounds were employed to investigate their electrochemical responses on BOMC and OMC modified glassy carbon electrodes. The BOMC, with more defective sites, exhibited high activity toward the electroactive compounds. The property of BOMC of supporting platinum nanoparticle catalyst was examined. Pt nanoparticles were loaded onto BOMC and OMC, and this was confirmed by TEM, XPS and thermogravimetric analysis. Pt nanoparticles with an average diameter of 2.62 nm were deposited on BOMC. The doping of boron into OMC facilitates the dispersion of Pt nanoparticles. Pt nanoparticles supported on BOMC (Pt-BOMC) and Pt nanoparticles supported on OMC (Pt-OMC) were electrochemically characterized. The electrocatalytic activity of Pt-BOMC toward methanol oxidation reaction was compared with that of Pt-OMC and commercial Pt-C catalyst. The results show that the electrocatalytic activity of BOMC is significantly higher than that of other used catalysts. PMID:24910045

Nsabimana, Anaclet; Bo, Xiangjie; Zhang, Yufan; Li, Mian; Han, Ce; Guo, Liping

2014-08-15

90

Ordered mesoporous carbon/Nafion as a versatile and selective solid-phase microextraction coating.  

PubMed

In this study, ordered mesoporous carbon (OMC) with large surface area (1019m(2)g(-1)), uniform mesoporous structure (pore size distribution centering at 4.2nm) and large pore volume (1.46cm(3)g(-1)) was synthesized using 2D hexagonally mesoporous silica MSU-H as the hard template and sucrose as the carbon precursor. The as-synthesized OMC was immobilized onto a stainless steel wire using Nafion as a binder to prepare an OMC/Nafion solid-phase microextraction (SPME) coating. The extraction characteristics of the OMC/Nafion coating were extensively investigated using a wide range of analytes including non-polar (light petroleum and benzene homologues) and polar compounds (amines and phenols). The OMC/Nafion coating exhibited much better extraction efficiency towards all selected analytes than that of a multi-walled carbon nanotubes/Nafion coating with similar length and thickness, which is ascribed to its high surface area, well-ordered mesoporous structure and large pore volume. When the OMC/Nafion coating was used to extract a mixture containing various kinds of analytes, it possessed excellent extraction selectivity towards aromatic non-polar compounds. In addition, the feasibility of the OMC/Nafion coating for application in electrochemically enhanced SPME was demonstrated using protonated amines as model analytes. PMID:25249487

Zeng, Jingbin; Zhao, Cuiying; Chen, Jingjing; Subhan, Fazle; Luo, Liwen; Yu, Jianfeng; Cui, Bingwen; Xing, Wei; Chen, Xi; Yan, Zifeng

2014-10-24

91

Ordered mesoporous carbon functionalized with poly-azure B for electrocatalytic application  

Microsoft Academic Search

Ordered mesoporous carbon (OMC) functionalized with poly-azure B (denoted as PAB\\/OMC) composite-modified electrode was fabricated by electropolymerizing azure B (AB) on the surface of glassy carbon electrode (GCE). OMC provides a conductive network for the polymer immobilization. The new nanocomposite film was characterized by cyclic voltammetry (CV) and scanning electron microscopy (SEM). The results indicated that this poly nanocomposite modified

Jue Fang; Bin Qi; Li Yang; Liping Guo

2010-01-01

92

Pyrolytic Synthesis of Carbon Nanotubes from Sucrose on a Mesoporous Silicate  

NASA Technical Reports Server (NTRS)

Multiwall carbon nanotubes were synthesized from sucrose by a pyrolytic technique using mesoporous MCM-41 silicate templates without transition metal catalysts. The Nanotubes were examined in the carbon/silicate composite and after dissolution of the silicate. High resolution transmission electron microscopy study of the multiwall nanotubes showed them to be 15 nm in diameter, 200 nm in length and close-ended. There was variation in crystallinity with some nanotubes showing disordered wall structures.

Abdel-Fattah, Tarek; Siochi, Mia; Crooks, Roy

2005-01-01

93

Numerical Study of Thermal Conductivities of Carbon-Based Mesoporous Composites  

NASA Astrophysics Data System (ADS)

The thermal conductivities of ordered mesoporous carbon CMK-3 filled with Al nanoclusters were studied in this article. CMK-3 is a typical example of carbon rods which are arranged in a relatively regular two-dimensional hexagonal array. The initial structure of CMK-3 was generated from the amorphous carbon and validated by XRD simulation which is coincident with experimental data. The thermal conductivities of carbon rods in CMK-3 and Al nanoclusters with 133 atoms were simulated by an equilibrium molecular dynamics method. Then, the effective thermal conductivity (ETC) of a mesoporous composite, CMK-3 filled with , was obtained via one-dimensional heat conduction analysis. The influences of the substrate porosity, nanocluster filling ratio, and temperature were discussed. As an anisotropic material, ETCs along the and directions are extremely poor, due to the overwhelming effect of the air thermal resistance. However, in the direction, the ETC improves almost linearly as the porosity decreases, and the value is much higher than those of and directions. In the case of a 70 % filling ratio, when the porosity is below 59.7 %, the ETC in the direction exceeds the thermal conductivity of Al nanoclusters and approaches a peak value around the melting temperature of nanoclusters. The results indicate that the carbon-based mesoporous CMK-3 filled with Al nanoclusters might become a promising phase change material.

Feng, Daili; Feng, Yanhui; Zhang, Xinxin

2014-10-01

94

Electrochemical behavior of methyl parathion and its sensitive determination at a glassy carbon electrode modified with ordered mesoporous carbon  

Microsoft Academic Search

Ordered mesoporous carbon (OMC) was synthesized and used to modify the surface of a glassy carbon (GC) electrode. Due to the\\u000a unique properties of OMC, a decrease in the overvoltage of the reduction potential of methyl parathion (MP) (to ca. 219 mV)\\u000a and a 76-fold increase in the peak current are observed (compared with a bare GC electrode). The absorption capacity

Deng Pan; Shumin Ma; Xiangjie Bo; Liping Guo

2011-01-01

95

Mesoporous carbon as a novel drug carrier of fenofibrate for enhancement of the dissolution and oral bioavailability.  

PubMed

The purpose of this study was to develop mesoporous carbon loaded with a poorly watersoluble drug to enhance the drug dissolution and improve the oral bioavailability. Mesoporous carbon was synthesized using Pluronic 127 triblock polymer (F127), TEOS and phenolic resins. Fenofibrate (FFB) was chosen as a model drug and loaded onto mesoporous carbon using three different loading methods involving incipient wetness impregnation, and the solvent and melting methods. The effect of the physical state and the specific surface area were investigated using nitrogen adsorption, transmission electron microscopy (TEM), powder X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was found that the physicochemical properties of the drug as well as the drug loading methods had critical effects on the drug release rate. In vitro drug release studies showed that incorporation of FFB in mesoporous carbon greatly enhanced the dissolution rate in comparison with that of the pure crystalline drug. Moreover, the oral bioavailability of the drug from mesoporous carbon was higher than that of FFB commercial capsules. Furthermore, mesoporous carbon produced no irritation of the mucosa of the gastrointestinal tract as shown by gastric mucosa irritation test. PMID:23688621

Niu, Xia; Wan, Long; Hou, Zhong; Wang, Tianyi; Sun, Changshan; Sun, Jin; Zhao, Peng; Jiang, Tongying; Wang, Siling

2013-08-16

96

Facile synthesis of magnetic mesoporous hollow carbon microspheres for rapid capture of low-concentration peptides.  

PubMed

Mesoporous and hollow carbon microspheres embedded with magnetic nanoparticles (denoted as MHM) were prepared via a facile self-sacrificial method for rapid capture of low-abundant peptides from complex biological samples. The morphology, structure, surface property, and magnetism were well-characterized. The hollow magnetic carbon microspheres have a saturation magnetization value of 130.2 emu g(-1) at room temperature and a Brunauer-Emmett-Teller specific surface area of 48.8 m(2) g(-1) with an average pore size of 9.2 nm for the mesoporous carbon shell. The effectiveness of these MHM affinity microspheres for capture of low-concentration peptides was evaluated by standard peptides, complex protein digests, and real biological samples. These multifunctional hollow carbon microspheres can realize rapid capture and convenient separation of low-concentration peptides. They were validated to have better performance than magnetic mesoporous silica and commercial peptide-enrichment products. In addition, they can be easily recycled and present excellent reusability. Therefore, it is expected that this work may provide a promising tool for high-throughput discovery of peptide biomarkers from biological samples for disease diagnosis and other biomedical applications. PMID:24992375

Cheng, Gong; Zhou, Ming-Da; Zheng, Si-Yang

2014-08-13

97

Photoreactive mesoporous carbon/Bi2WO6 composites: Synthesis and reactivity  

NASA Astrophysics Data System (ADS)

In order to develop highly efficient visible-light induced photocatalysts, Bi2WO6 powders and mesoporous carbon (MC)-modified Bi2WO6 (MC/Bi2WO6) photocatalysts were synthesized via a simple hydrothermal process in this paper. The samples of Bi2WO6 and MC/Bi2WO6 were characterized by X-ray diffraction (XRD), UV-visible spectroscopy, scanning electron microscopy (SEM) and BET surface area analysis, and their photocatalytic activity were evaluated by photocatalytic decoloration of rhodamine B (RhB) aqueous solution under visible light. It was found that the presence of MC could significantly improve the crystallization of Bi2WO6 species and photoabsorption property of Bi2WO6 in the visible region. The results also showed that the BET surface areas of MC/Bi2WO6 composites were larger than that of the pure Bi2WO6 and the photocatalytic activity of the MC/Bi2WO6 is much higher than that of Bi2WO6 with the optimum effect occurring at RMC = 0.10 (the weight ratio of MC to Bi2WO6). Close investigation revealed that the surface area, grain size and charge transfer of the as-prepared MC/Bi2WO6 composites could improve the photocatalytic activities.

Chen, Su-Hua; Yin, Zhen; Luo, Sheng-Lian; Li, Xue-Jun; Yang, Li-Xia; Deng, Fang

2012-10-01

98

Hierarchical nanostructured spherical carbon with hollow core/mesoporous shell as a highly efficient counter electrode in CdSe quantum-dot-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Hierarchical nanostructured spherical carbon with hollow core/mesoporous shell (HCMS) was explored as a counter electrode in CdSe quantum-dot-sensitized solar cells. Compared with conventional Pt electrodes and commercially available activated carbon, the HCMS carbon counter electrode exhibits a much larger fill factor due to the considerably decreased charge transfer resistance at the interface of the counter electrode/polysulfide electrolyte. Furthermore, a solar cell with the HCMS carbon counter electrode presents a high power conversion efficiency of up to 3.90% as well as an incident photon-to-current conversion efficiency peak of 80%.

Fan, Sheng-Qiang; Fang, Baizeng; Kim, Jung Ho; Kim, Jeum-Jong; Yu, Jong-Sung; Ko, Jaejung

2010-02-01

99

Mesoporous carbon-carbon nanotube-sulfur composite microspheres for high-areal-capacity lithium-sulfur battery cathodes.  

PubMed

Lithium-sulfur (Li-S) batteries offer theoretical energy density much higher than that of lithium-ion batteries, but their development faces significant challenges. Mesoporous carbon-sulfur composite microspheres are successfully synthesized by combining emulsion polymerization and the evaporation-induced self-assembly (EISA) process. Such materials not only exhibit high sulfur-specific capacity and excellent retention as Li-S cathodes but also afford much improved tap density, sulfur content, and areal capacity necessary for practical development of high-energy-density Li-S batteries. In addition, when incorporated with carbon nanotubes (CNTs) to form mesoporous carbon-CNT-sulfur composite microspheres, the material demonstrated superb battery performance even at a high current density of 2.8 mA/cm(2), with a reversible capacity over 700 mAh/g after 200 cycles. PMID:24090278

Xu, Terrence; Song, Jiangxuan; Gordin, Mikhail L; Sohn, Hiesang; Yu, Zhaoxin; Chen, Shuru; Wang, Donghai

2013-11-13

100

Fabrication and characterization of a zirconia/multi-walled carbon nanotube mesoporous composite.  

PubMed

A zirconia/multi-walled carbon nanotube (ZrO2/MWCNT) mesoporous composite was fabricated via a simple method using a hydrothermal process with the aid of the cationic surfactant cetyltrimethylammonium bromide (CTAB). Transmission electron microscopy (TEM), N2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques were used to characterize the as-made samples. The cubic ZrO2 nanocrystallites were observed to overlay the surface of MWCNTs, which resulted in the formation of a novel mesoporous-nanotube composite. On the basis of a TEM analysis of the products from controlled experiment, the role of the acid-treated MWCNTs and CTAB was proposed to explain the formation of the mesoporous-nanotube structure. The as-made composite possessed novel properties, such as a high surface area (312 m(2)·g(-1)) and a bimodal mesoporous structure (3.18 nm and 12.4 nm). It was concluded that this composite has important application value due to its one-dimensional hollow structure, excellent electric conductivity and large surface area. PMID:23910298

Wang, Zonghua; Xia, Jianfei; Xia, Yanzhi; Lu, Caiyu; Shi, Guoyu; Zhang, Feifei; Zhu, Fuqiang; Li, Yanhui; Xia, Linhua; Tang, Jie

2013-10-01

101

Two-dimensional mesoporous carbon nanosheets and their derived graphene nanosheets: synthesis and efficient lithium ion storage.  

PubMed

We report a new solution deposition method to synthesize an unprecedented type of two-dimensional ordered mesoporous carbon nanosheets via a controlled low-concentration monomicelle close-packing assembly approach. These obtained carbon nanosheets possess only one layer of ordered mesopores on the surface of a substrate, typically the inner walls of anodic aluminum oxide pore channels, and can be further converted into mesoporous graphene nanosheets by carbonization. The atomically flat graphene layers with mesopores provide high surface area for lithium ion adsorption and intercalation, while the ordered mesopores perpendicular to the graphene layer enable efficient ion transport as well as volume expansion flexibility, thus representing a unique orthogonal architecture for excellent lithium ion storage capacity and cycling performance. Lithium ion battery anodes made of the mesoporous graphene nanosheets have exhibited an excellent reversible capacity of 1040 mAh/g at 100 mA/g, and they can retain at 833 mAh/g even after numerous cycles at varied current densities. Even at a large current density of 5 A/g, the reversible capacity is retained around 255 mAh/g, larger than for most other porous carbon-based anodes previously reported, suggesting a remarkably promising candidate for energy storage. PMID:23282081

Fang, Yin; Lv, Yingying; Che, Renchao; Wu, Haoyu; Zhang, Xuehua; Gu, Dong; Zheng, Gengfeng; Zhao, Dongyuan

2013-01-30

102

Heterogeneous catalytic activity of platinum nanoparticles hosted in mesoporous silica thin films modified with polyelectrolyte brushes.  

PubMed

Platinum nanoparticles of 3 nm diameter were included in mesoporous silica thin films by controlling the mesopore surface charge with a short polymer brush. This metal-polymer-mesopore nanocomposite presents high catalytic activity toward ammonia oxidation at low temperatures with 4.5% weight platinum loading. An anomalous partial selectivity toward nitrous oxide is observed for the first time, which can be traced back to the synergy of the particles and modified surface. This effect opens a path toward the design of nanocomposite catalysts with highly controlled environments, in which the size- and function-controlled cavities can be tuned in order to lower the reaction barriers. PMID:24020748

Rafti, Matías; Brunsen, Annette; Fuertes, M Cecilia; Azzaroni, Omar; Soler-Illia, Galo J A A

2013-09-25

103

Phenol-formaldehyde carbon with ordered/disordered bimodal mesoporous structure as high-performance electrode materials for supercapacitors  

NASA Astrophysics Data System (ADS)

A novel phenol-formaldehyde carbon with ordered/disordered bimodal mesoporous structure is synthesized by the facile evaporation induced self-assembly strategy under a basic aqueous condition with SiO2 particles as template. The prepared bimodal mesoporous carbons (BMCs) are composed of ordered mesoporous and disordered mesoporous with diameter of about 3.5 nm and 7.0 nm, respectively. They can be employed as supercapacitor electrodes in H2SO4 aqueous electrolyte after the simple acid-treatment. BMC exhibits an exceptional specific capacitance of 344 F g-1 at the current density of 0.1 A g-1, although it has a relatively low surface area of 722 m2 g-1. And the BMC electrode displays an excellent cycling stability over 10,000 cycles.

Cai, Tingwei; Zhou, Min; Han, Guangshuai; Guan, Shiyou

2013-11-01

104

Stepwise synthesis, characterization, and electrochemical properties of ordered mesoporous carbons containing well-dispersed Pt nanoparticles using a functionalized template route  

SciTech Connect

A stepwise method is described for the accurately controlled growth of Pt nanoparticles supported on ordered mesoporous carbons (Pt-OMC) by the nanocasting of carbon and metal precursors in the pore channels of mesoporous silicas functionalized with Si-H groups. Results obtained from N{sub 2} adsorption/desorption isotherms and transmission electron microscopy showed well-dispersed Pt nanoparticles (2-3 nm) on Pt-OMC with high surface area (837 m{sup 2} g{sup -1}) and regular pore channels (2.9 nm), which facilitate reactant/product diffusion. X-ray diffraction and X-ray photoelectron spectroscopy indicated that Pt nanoparticles in the Pt-OMC sample were mostly present in the metallic form of a face-centered cubic (fcc) crystalline structure. The Pt-OMC catalyst was found to have superior electrocatalytic properties during oxygen reduction reaction as compared to typical commercial electrocatalysts. - Graphical abstract: A novel procedure has been developed to synthesize ordered carbon mesoporous carbons (OMC) containing well-dispersed and highly electrocatalytic Pt nanoparticles (Pt-OMC) for oxygen reduction reaction. Highlights: > A novel method to incorporate nanosized Pt particles on nanostructure carbons. > Functionalized silica templates were used to control size and distribution of Pt nanoparticles. > Electrochemical measurements of oxygen reduction demonstrated high catalytic activity compared to common commercial catalysts.

Liu, Shou-Heng, E-mail: shliu@kuas.edu.tw [Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan (China); Chen, Shih-Che [Department of Chemical and Materials Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung 80778, Taiwan (China)

2011-09-15

105

Mesoporous Carbon-based Materials for Alternative Energy Applications  

E-print Network

modified Carbon-Silica Composite Aerogels." Nano Letters 2(Carbon nanotubes (CNTs) exhibit superior mechanical, thermal, and electrical properties, attracting great interest as advanced nano-reinforcements in various types of polymer composites (

Cross, Kimberly Michelle

2012-01-01

106

The electrochemical performance of ordered mesoporous carbon/nickel compounds composite material for supercapacitor  

SciTech Connect

A series of high performance ordered mesoporous carbon/nickel compounds composites have been synthesized by a combination of incipient wetness impregnation and hydrothermal method for the first time. X-ray diffraction (XRD), N{sub 2} adsorption/desorption isotherms and transmission electron microscopy (TEM) are used to characterize the composites derived at the hydrothermal temperature of 125, 150, 175, 200, 250, 275 and 300 {sup o}C. The formation of nanosized nickel compounds, fully inside the mesopore system, was confirmed with XRD and TEM. An N{sub 2} adsorption/desorption isotherms measurements still revealed mesoporosity for the host/guest compounds. It is noteworthy that an OMC/nickel nitrate hydroxide hydrate composite (OMCN-150) exhibits more excellent performance. Based on the various hydrothermal temperatures of the composite, the capacitance of an OMCN-150 delivering the best electrochemical performance is about 2.4 (5 mV s{sup -1}) and 1.5 (50 mV s{sup -1}) times of the pristine OMC. The capacitance retention of an OMCN-150 is 96.1%, which indicates that the electrochemical performance of the supercapacitor is improved greatly, and represents novel research and significant advances in the field of electrode composite materials for supercapacitor. -- Graphical abstract: A series of high performance nickel compound/ordered mesoporous carbon composites were synthesized by a combination of incipient wetness impregnation and hydrothermal method for the first time. Display Omitted

Feng, Jicheng; Zhao, Jiachang; Tang, Bohejin; Liu, Ping [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Xu, Jingli, E-mail: jinglixu@sues.edu.c [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China)

2010-12-15

107

PtRu nanoparticles supported on nitrogen-doped polyhedral mesoporous carbons as electrocatalyst for methanol oxidation  

NASA Astrophysics Data System (ADS)

Nitrogen-doped mesoporous carbons (NMPCs) with well-developed polyhedral morphology were prepared by direct carbonization of zeolitic imidazolate framework-8 (ZIF-8) nanopolyhedrons. The fantastic structural characteristics of NMPCs such as ultrahigh BET surface area (1960 m2 g-1), large pore volume (1.16 cm3 g-1), and nitrogen doping make it an excellent catalyst support. PtRu nanoparticles (with a size of approximately 1.9 nm) were homogeneously supported on NMPCs by microwave-assisted reduction in ethylene glycol, and the obtained PtRu/NMPCs catalyst shows a significantly higher electrocatalytic activity and stability for methanol oxidation than the typical commercial PtRu/C (E-TEK) catalyst.

Zhang, Yunsong; Zhu, Rong; Cui, Ying; Zhong, Jindi; Zhang, Xiaohua; Chen, Jinhua

2014-04-01

108

Oxidation and EDX elemental mapping characterization of an ordered mesoporous carbon: Pb(II) and Cd(II) removal  

NASA Astrophysics Data System (ADS)

The adsorption of the metallic ions Cd(II) and Pb(II) onto the surface of the mesoporous activated carbon CMK-3 is presented. The carbon was synthesized from a SBA-15 template by the method of nanocasting and oxidized in an aqueous solution with nitric acid (HNO3). The effect of temperature and oxidation time was studied. The presence of the functional groups, formed during the oxidation, onto the carbon surface was confirmed by FT-IR analysis. The structural and textural properties of activated carbon were obtained by nitrogen adsorption, SEM, EDX and HTEM. The surface area of the CMK-3 is 1170 m2/g, and it contains 96.7% of carbon and 3.3% of oxygen, whereas the oxidized CMK-3-O exhibits a surface area of 944 m2/g and contains 85.2% of carbon and 14.8% of oxygen. The adsorption isotherms follow the Langmuir model and the maximum amount of adsorbed ions was 40.4 mg/g for Cd(II) and 94 mg/g for Pb(II) at pH 5 and 25 °C. The spatial distribution and amount of oxygen and adsorbed metal ions were determined by elemental mapping and line scanning EDX. It was confirmed that the amount of oxygen is directly related with the amount of adsorbed ions.

Moreno-Tovar, R.; Terrés, E.; Rangel-Mendez, J. Rene

2014-06-01

109

Production of activated carbon cloth with controlled structure and porosity from a new precursor  

Microsoft Academic Search

The production of micro and mesoporous activated carbon cloth (ACC) from commercial acrylic textile fibres by physical activation\\u000a with carbon dioxide and the addition of boric acid and sodium hydrogen phosphate as impregnants is reported. The use of sodium\\u000a hydrogen phosphate leads to samples with greater mesopore volume whereas other ACC production conditions studied mainly result\\u000a in microporous materials. This

J. M. Valente Nabais; T. Canário; P. J. M. Carrott; M. M. L. Ribeiro Carrott

2007-01-01

110

Control of ordering and structure in soft templated mesoporous carbon films by use of selective solvent additives.  

PubMed

The structure of ordered mesoporous carbons fabricated using poly(styrene-block-N,N,-dimethyl-n-octadecylamine p-styrenesulfonate) (PS-b-PSS-DMODA) as the template and phenolic resin (resol) as the carbon source can be easily manipulated by inclusion of low concentrations of low volatility selective solvents in the casting solution. Casting from neat methyl ethyl ketone yields a disordered structure even upon thermal annealing. However, addition of both dioctyl phthalate (DOP, PS selective) and dimethyl sulfoxide (DMSO, resol and PSS-DMODA selective) at modest concentrations to this casting solution provides sufficient mobility to produce highly ordered films with cylindrical mesopores. The DOP acts to swell the hydrophobic domain and can more than double the mesopore size, while the DMSO acts to swell the resol phase. Moreover, the surface area of the mesoporous carbons increases significantly as the meosopore size increases. This is a result of the decrease in wall thickness, which can be ascertained by the constant d-spacing of the mesostructure as the pore size increases. This behavior is counter to the typical effect of pore swelling agents that increase the pore size and decrease the surface area. Moreover, with only 4 wt % DOP/DMSO in the solution (20 wt % relative to solids), the scattering profiles exhibit many orders of diffraction, even upon carbonization, which is not typically observed for soft templated films. Variation in the concentration of DOP and DMSO during casting enables facile tuning of the structure of mesoporous carbon films. PMID:23738851

Qiang, Zhe; Xue, Jiachen; Stein, Gila E; Cavicchi, Kevin A; Vogt, Bryan D

2013-07-01

111

Microporous and mesoporous carbide-derived carbons for strain modification of electromechanical actuators.  

PubMed

Low-voltage stimuli-responsive actuators based on carbide-derived carbon (CDC) porous structures were demonstrated. Bending actuators showed a differential electromechanical response defined by the porosity of the CDC used in the electrode layer. Highly porous CDCs prepared from TiC (mainly microporous), B4C (micromesoporous), and Mo2C (mainly mesoporous) precursors were selected to demonstrate the influence of porosity parameters on the electromechanical performance of actuators. CDC-based bending-type actuators showed a porosity-driven displacement response over a frequency range of 200 to 0.005 Hz at an applied excitation voltage of ±2 V. The displacement response of the CDC actuators increased with an increasing number of mesopores in the electrode layer, and the generated strain of the bending actuators was proportional to the total porosity (micropores and mesopores) of the CDC. The modifiable electromechanical response that arises from the precise porosity control attained through tailoring the CDC architecture demonstrates that these actuators hold great promise for smart, low-voltage-driven actuation devices. PMID:24580143

Torop, Janno; Arulepp, Mati; Sugino, Takushi; Asaka, Kinji; Jänes, Alar; Lust, Enn; Aabloo, Alvo

2014-03-18

112

Highly ordered magnetic mesoporous silicas for effective elimination of carbon monoxide  

SciTech Connect

Catalysts based on crystalline nanoparticles of Fe metal supported on mesoporous silica have been developed. The synthetic process involves hydrogen reduction processing for high abundant Fe metal nanoparticles within the mesopores, in which impregnated Fe salt in the inner nanopores of mesoporous silica is thermally treated under hydrogen at 500 Degree-Sign C. Detailed characterization was achieved by XRD, XPS, BET, and HR-TEM techniques. The catalytic efficiency was demonstrated as a function of the used amounts and reaction time. The results show that more than 90% of the carbon monoxide was eliminated at room temperature during a period 80 min with 0.5 g of catalyst. - Graphical abstract: Strategy for the preparation of highly abundant Fe nanoparticle embedded MS catalyst by hydrogen reduction process and HR-TEM images of cross-sectional and top view. Highlights: Black-Right-Pointing-Pointer MS based heterogeneous catalyst with Fe nanoparticles were demonstrated for CO elimination. Black-Right-Pointing-Pointer Highly Fe nanoparticle embedded MS catalyst prepared by hydrogen reduction process. Black-Right-Pointing-Pointer Systematic characterization was achieved by XRD, XPS, BET, and HR-TEM analyses. Black-Right-Pointing-Pointer More than 90% of the CO was eliminated at RT during 80 min with 0.5 g of catalyst.

Lee, Jiho [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of); Department of Chemistry, Inha University, Incheon 402-751 (Korea, Republic of); Ho Chang, Jeong, E-mail: jhchang@kicet.re.kr [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of)

2012-04-15

113

Synthesis and characteristics of continuous mesoporous carbon films by a rapid solvent evaporation method  

NASA Astrophysics Data System (ADS)

Carbon films with a well-developed meso-porosity were synthesized directly by the carbonization of sulfuric-acid-treated P123 triblock copolymer/silica nanocomposite films, which were prepared from dip-coating technique through an association of sol-gel and evaporation-induced self-assembly process, and the residual silica was removed subsequently via HF-etching. P123 was employed as both structuring agent for self-assembly of tetraethyl orthosilicate and carbon precursor. The sulfuric acid solution was used as a catalyst for cross-linking of P123/silica in order to improve the carbon yield for the continuity of carbon films. Investigations by Field emission scanning electron microscopy (FESEM), X-ray diffraction, nitrogen adsorption measurement and transmission electron microscopy (TEM) indicate that the hybrid carbon/silica mesoporous films are preserved perfectly after the carbonization. When the silica is removed by acid treatment, continuous carbon films with an ordered symmetric structure are still kept well. The carbon films obtained are composed of carbon nanotubes with the diameter of around 6 nm, and the lengths of nanotubes affiliating with each other vary from about 100 nm to several micrometers, which were measured by FESEM and TEM.

Wang, Xiaoxian; Li, Tiehu; Ji, Yongbin; Ai, Yanling; Lin, Qilang

2008-12-01

114

Preparation and drug release behavior of temperature-responsive mesoporous carbons  

NASA Astrophysics Data System (ADS)

A temperature-responsive composite based on poly (N-isopropylacrylamide) (PNIPAAm) and ordered mesoporous carbons (OMCs) has been successfully prepared by a simple wetness impregnation technique. The structures and properties of the composite were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), N 2 sorption, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The results showed that the inclusion of PNIPAAm had not greatly changed the basic ordered pore structure of the OMCs. Ibuprofen (IBU) was selected as model drug, and in vitro test of IBU release exhibited a temperature-responsive controlled release delivery.

Wang, Xiufang; Liu, Ping; Tian, Yong

2011-06-01

115

Construction of label-free electrochemical immunosensor on mesoporous carbon nanospheres for breast cancer susceptibility gene.  

PubMed

In this contribution, mesoporous carbon nanospheres (MCN) were used to fabricate a label-free electrochemical immunosensor for breast cancer susceptibility gene (BRCAl). The detection platform was constructed by conjugation of anti-BRCA1 on glassy carbon electrodes which were modified by mesoporous carbon nanospheres-toluidine blue nanocomposite (MCN-TB)/room temperature ionic-liquid (RTIL) composited film. TB was adsorbed onto MCN and acted as a redox probe. The electroactivity of TB was greatly enhanced in the presence of MCN. The good conductivity of MCN and BMIM·BF4 could promote the electron transfer and thus enhance the detection sensitivity. Moreover, the large surface area of MCN and the protein-binding properties of BMIM·BF4 could greatly increase the antibody loading. The specific antibody-antigen immunoreaction on the electrode surface resulted in a decrease of amperometric signal of the electrode. Under optimized conditions, the amperometric signal decreased linearly with BRCAl concentration in the range of 0.01-15 ng mL(-1) with a low detection limit of 3.97 pg mL(-1). The immunosensor exhibits high sensitivity, good selectivity and stability. PMID:23498687

Fan, Haixia; Zhang, Yong; Wu, Dan; Ma, Hongmin; Li, Xiaojing; Li, Yan; Wang, Huan; Li, He; Du, Bin; Wei, Qin

2013-04-01

116

Using mesoporous carbon electrodes for brackish water desalination  

Microsoft Academic Search

Electrosorptive deionisation is an alternative process to remove salt ions from the brackish water. The porous carbon materials are used as electrodes. When charged in low voltage electric fields, they possess a highly charged surface that induces adsorption of salt ions on the surface. This process is reversible, so the adsorbed salt ions can be desorbed and the electrode can

Linda Zou; Lixia Li; Huaihe Song; Gayle Morris

2008-01-01

117

Graphitic Mesoporous Carbon as a Support of Promoted Rh Catalysts for Hydrogenation of Carbon Monoxide to Ethanol  

SciTech Connect

Graphitic mesoporous carbon (GMC), prepared through high-temperature graphitization of soft-templated amorphous mesoporous carbon (AMC), was used as the support for Mn, Li, and Fe triple-promoted Rh catalysts for CO hydrogenation to ethanol. The use of GMC results in C{sub 2}H{sub 5}OH selectivity and formation rate comparable to nonporous SiO{sub 2} support along with a significant inhibition on the formation of undesired CH{sub 4} and light hydrocarbons at the expense of appreciable amounts of CO{sub 2} produced. The better catalytic performance of promoted-Rh/GMC than those supported on other carbon allotropes (AMC and non-porous graphitic carbon black) seems to be associated with the specific graphitic structure and mesoporosity of GMC. The surface modification of GMC by wet oxidation leads to considerable increases in C{sub 2}H{sub 5}OH selectivity and formation rate. The modified GMC as a support shows substantially greater CO{sub 2}-free selectivity for C{sub 2}H{sub 5}OH than the SiO{sub 2}.

Chai, Songhai [ORNL; Howe, Jane Y [ORNL; Wang, Xiqing [ORNL; Kidder, Michelle [ORNL; Schwartz, Viviane [ORNL; Golden, Melissa L [ORNL; Overbury, Steven {Steve} H [ORNL; Dai, Sheng [ORNL; Jiang, Deen [ORNL

2012-01-01

118

Accidental extinction in powder XRD intensity of porous crystals: Mesoporous carbon crystal CMK-5 and layered zeolite-nanosheets  

Microsoft Academic Search

CMK-5 mesoporous carbon crystals with p6mm symmetry and different carbon-wall thicknesses were prepared using furfuryl alcohol. We clearly observed that the XRD intensity of the 10 reflection diminishes at a certain thickness of carbon-wall, i.e., an “accidental extinction” happens in CMK-5. In order to make clear the condition of the “accidental extinction”, XRD intensity is analytically formulated\\/calculated for two-dimensional system

Kristina Lund; Norihiro Muroyama; Osamu Terasaki

2010-01-01

119

Adsorption removal of acid black 1 from aqueous solution using ordered mesoporous carbon  

NASA Astrophysics Data System (ADS)

A novel ordered mesoporous carbon CMK-3 and synthetic CMK-3 containing nitrogen functional groups by ammonia-treated were applied for acid black 1(AB1) dye adsorption. The ammonia-treated(chemical vapor deposition method) before and after CMK-3 were characterized by using a Micrometitics ASAP 2020 surface area analyzer (ASAP 2020), Fourier transform infrared spectrophotometer (FT-IR), X-ray Photoelectron Spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscope (SEM) and equilibrium studies. This result indicates that the prepared CMK-3 and modified CMK-3 were almost uniform, as rope-like domains and their uniform mesopore with diameter centered at 3.2 nm and 3.7 nm. The FIIR analysis depicted that the presence of a variety of new basic functional groups on the modified CMK-3 surface. Several effect variables of pH, dye concentration and temperature were studied. The pseudo second-order model showed the ?tter well to agree with the kinetic data. The experimental data were analyzed by the Langmuir and Freundlich models, with the latter found to closely the isotherm model. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The results show that CMK-3 using ammonia gas modified by thermal treatment system is an effective method to improvement capacity as it shows the highest adsorption capacity of AB1, as compared to the unmodified CMK-3 and the bamboo-based carbon, respectively.

Peng, Xiaoming; Hu, Xijun; Fu, Dafang; Lam, Frank L. Y.

2014-03-01

120

Bactericidal property and biocompatibility of gentamicin-loaded mesoporous carbonated hydroxyapatite microspheres.  

PubMed

Implant-associated infection is a serious problem in orthopaedic surgery. One of the most effective ways is to introduce a controlled antibiotics delivery system into the bone filling materials, achieving sustained release of antibiotics in the local sites of bone defects. In the present work, mesoporous carbonated hydroxyapatite microspheres (MCHMs) loaded with gentamicin have been fabricated according to the following stages: (i) the preparation of the MCHMs by hydrothermal method using calcium carbonate microspheres as sacrificial templates, and (ii) loading gentamicin into the MCHMs. The MCHMs exhibit the 3D hierarchical nanostructures constructed by nanoplates as building blocks with mesopores and macropores, which make them have the higher drug loading efficiency of 70-75% than the conventional hydroxyapatite particles (HAPs) of 20-25%. The gentamicin-loaded MCHMs display the sustained drug release property, and the controlled release of gentamicin can minimize significantly bacterial adhesion and prevent biofilm formation against S. epidermidis. The biocompatibility tests by using human bone marrow stromal cells (hBMSCs) as cell models indicate that the gentamicin-loaded MCHMs have as excellent biocompatibility as the HAPs, and the dose of the released gentamicin from the MCHMs has no toxic effects on the hBMSCs. Hence, the gentamicin-loaded MCHMs can be served as a simple, non-toxic and controlled drug delivery system to treat bone infections. PMID:23910253

Guo, Ya-Jun; Long, Teng; Chen, Wei; Ning, Cong-Qin; Zhu, Zhen-An; Guo, Ya-Ping

2013-10-01

121

Polypyrrole-derived nitrogen and oxygen co-doped mesoporous carbons as efficient metal-free electrocatalyst for hydrazine oxidation.  

PubMed

We demonstrate that polypyrrole-derived nitrogen and oxygen co-doped mesoporous carbons can serve as efficient, metal-free electrocatalysts for hydrazine oxidation reaction, with low overpotential and high current density. The materials' structures and the nature and type of their included dopants, which can be controlled by varying the synthetic conditions, can affect the electrocatalytic properties of the materials. PMID:25123849

Meng, Yuying; Zou, Xiaoxin; Huang, Xiaoxi; Goswami, Anandarup; Liu, Zhongwu; Asefa, Tewodros

2014-10-01

122

Electrochemical control of ion transport through a mesoporous carbon membrane  

SciTech Connect

The transport of fluids through nanometer scale channels typically on the order of 1 -100 nm often exhibit unique properties compared to the bulk fluid. These phenomena occur because the channel dimensions and molecular size become comparable to the range of several important forces including electrostatic and van der Waals forces. Small changes in properties such as the electric double layer or surface charge can significantly affect molecular transport through the channels. Based on these emerging properties, a variety of nanofluidic devices such as nanofluidic transistors, nanofluidic diodes or lab-on-a-chip devices have been developed3-7 with a diverse range of applications including water purification, biomolecular sensing, DNA separation, and rectified ion transport. Nanofluidic devices are typically fabricated using expensive lithography techniques or sacrificial templates. Here we report a carbon-based, three-dimensional nanofluidic transport membrane that enables gated, or on/off, control of the transport of organic molecular species and metal ions using an applied electrical potential. In the absence of an applied potential, both cationic and anionic molecules freely diffuse across the membrane via a concentration gradient. However, when an electrochemical potential is applied, the transport of ions through the membrane is inhibited.

Surwade, Sumedh P [ORNL] [ORNL; Chai, Songhai [ORNL] [ORNL; Choi, Jai-Pil [ORNL] [ORNL; Wang, Xiqing [ORNL] [ORNL; Lee, Jeseung [ORNL] [ORNL; Vlassiouk, Ivan V [ORNL] [ORNL; Mahurin, Shannon Mark [ORNL] [ORNL; Dai, Sheng [ORNL] [ORNL

2014-01-01

123

Tailoring micro-mesoporosity in activated carbon fibers to enhance SO? catalytic oxidation.  

PubMed

Enhanced SO2 adsorption of activated carbon fibers is obtained by tailoring a specific micro-mesoporous structure in the fibers. This architecture is obtained via metal catalytic activation of the fibers with a novel precursor, cobalt naphthenate, which contrary to other precursors, also enhances spinnability and carbon fiber yield. In the SO2 oxidation, it is demonstrated that the combination of micropores and large mesopores is the main factor for an enhanced catalytic activity which is superior to that observed in other similar microporous activated carbon fibers. This provides an alternative way for the development of a new generation of catalytic material. PMID:24910032

Diez, Noel; Alvarez, Patricia; Granda, Marcos; Blanco, Clara; Gryglewicz, Gra?yna; Wróbel-Iwaniec, Iwona; Sliwak, Agata; Machnikowski, Jacek; Menendez, Rosa

2014-08-15

124

Capacitive performance of ordered mesoporous carbons with tunable porous texture in ionic liquid electrolytes  

NASA Astrophysics Data System (ADS)

Ordered mesoporous carbons with tunable pore size and surface chemical properties are prepared by doping boric acid using a hard-templating method. The capacitive performance of these carbons is investigated in two common ionic liquids of EMImBF 4 and EMImTSFI. As demonstrated by the structure analysis, the pore size increases from 3.3 to 5.7 nm and the content of oxygenated groups on the carbon surface increases from 2.0 to 5.2 mol% with the increase of the boron doping from 0 to 50 mol%. In ionic liquid electrolyte, the carbons mainly show typical electric double layer capacitance, and the capacitance retention ratio and ion diffusion in the carbon channels is determined to the surface chemical property. The prepared carbons present visible pseudo-capacitance due to the rapid redox reactions of the oxygenated groups in hydrophilic EMImBF 4, reflecting by the increasing of the specific surface capacitance, while no visible pseudo-capacitive behavior was observed in hydrophobic EMImTSFI.

Zhou, Jin; Xing, Wei; Zhuo, Shuping; Zhao, Yi

2011-11-01

125

Nanocomposite of LiFePO4 and mesoporous carbon prepared by microwave heating for rechargeable lithium batteries  

NASA Astrophysics Data System (ADS)

A nanocomposite of LiFePO4 and mesoporous carbon was synthesized from MgO-templated mesoporous carbon by microwave heating for use as a cathode material in rechargeable Li batteries. Our research group reported a composition method using a porous template in the a previous paper.[1] Despite its low carbon content, the present composite shows better electrochemical performance than our previously reported version. The LiFePO4 nanoparticles were homogeneously dispersed in the template because of the suppressed growth of LiFePO4 crystals in the template pores and small thermal gradient resulting from microwave heating. The three-dimensional conducting carbon network between the LiFePO4 nanoparticles led to excellent cycling stability and rate capability. No decrease in discharge capacity was observed up to 100 cycles, and 85% of the reversible capacity at a Crate of 0.1 was retained at a C-rate of 30.

Roh, Kwang Chul; Lee, Ho Jun; Lee, Jae-Won

2013-11-01

126

Adsorption studies of methylene blue and phenol onto vetiver roots activated carbon prepared by chemical activation  

Microsoft Academic Search

Vetiver roots have been utilized for the preparation of activated carbon (AC) by chemical activation with different impregnation ratios of phosphoric acid, XP (gH3PO4\\/g precursor): 0.5:1; 1:1 and 1.5:1. Textural characterization, determined by nitrogen adsorption at 77K shows that mixed microporous and mesoporous structures activated carbons (ACs) with high surface area (>1000m2\\/g) and high pore volume (up to 1.19cm3\\/g) can

Sandro Altenor; Betty Carene; Evens Emmanuel; Jacques Lambert; Jean-Jacques Ehrhardt; Sarra Gaspard

2009-01-01

127

Synthesis of hierarchical macro-/mesoporous solid-solution photocatalysts by a polymerization-carbonization-oxidation route: the case of Ce(0.49)Zr(0.37)Bi(0.14)O(1.93).  

PubMed

A hierarchical macro-/mesoporous Ce(0.49)Zr(0.37)Bi(0.14)O(1.93) solid-solution network has been synthesized on a large scale by means of a simple and general polymerization-carbonization-oxidation synthetic route. The as-prepared product has been characterized by SEM, XRD, TEM, BET surface area measurement, UV/Vis diffuse-reflectance spectroscopy, energy-dispersive X-ray spectroscopy (EDS), and photoelectrochemistry measurements. The photocatalytic activity of the product has been demonstrated through the photocatalytic degradation of methyl orange. Structural characterization has indicated that the hierarchical macro-/mesoporous solid-solution network not only contains numerous macropores, but also possesses an interior mesoporous structure. The mesopore size and BET surface area of the network have been measured as 2-25 nm and 140.5 m(2) g(-1), respectively. The hierarchical macro-/mesoporous solid-solution network with open and accessible pores was found to be well-preserved after calcination at 800 degrees C, indicating especially high thermal stability. Due to its high specific surface area, the synergistic effect of the coupling of macropores and mesopores, and its high crystallinity, the Ce(0.49)Zr(0.37)Bi(0.14)O(1.93) solid-solution material shows a strong structure-induced enhancement of visible-light harvest and exhibits significantly improved visible-light photocatalytic activity in the photodegradation of methyl orange compared with those of its other forms, such as mesoporous hollow spheres and bulk particles. PMID:20575115

Xi, Guangcheng; Ye, Jinhua

2010-08-01

128

Removal of less biodegradable dissolved organic matters in water by superconducting magnetic separation with magnetic mesoporous carbon  

NASA Astrophysics Data System (ADS)

Less biodegradable dissolved organic matters in water as typified by humic substances are known as precursors of carcinogenic trihalomethanes, and are removed about 60% by current advanced water treatments. However, further increase of the removal ratio is demand. In this study, magnetic mesoporous carbon (MMPC), which can adsorb the substances physically and be efficiently collected by using superconducting high gradient magnetic separation (HGMS), has been synthesized with coconut-shell-based activated carbon and ferric nitrate solution by the gas activation method. The MMPC has the maximum magnetization value of 30.7 emu/g and an adsorption ability of 87% to 10 mg/L humic acid in a short time. The standard MMPC having a magnetization of 6.43 emu/g was able to be separated at magnetic field of 2 T. Used MMPC regained the adsorption ability to 93.1% by N 2 reactivation heat treatment. These results show promise for application of current water treatments by superconducting HGMS, which is suitable for high-speed water treatment without secondary wastes.

Kondo, K.; Jin, T.; Miura, O.

2010-11-01

129

High performance sulfur, nitrogen and carbon doped mesoporous anatase-brookite TiO2 photocatalyst for the removal of microcystin-LR under visible light irradiation.  

PubMed

Carbon, nitrogen and sulfur (C, N and S) doped mesoporous anatase-brookite nano-heterojunction titania photocatalysts have been synthesized through a simple sol-gel method in the presence of triblock copolymer Pluronic P123. XRD and Raman spectra revealed the formation of anatase and brookite mixed phases. XPS spectra indicated the presence of C, N and S dopants. The TEM images demonstrated the formation of almost monodisperse titania nanoparticles with particle sizes of approximately 10nm. N2 isotherm measurements confirmed that both doped and undoped titania anatase-brookite materials have mesoporous structure. The photocatalytic degradation of the cyanotoxin microcystin-LR (MC-LR) has been investigated using these novel nanomaterials under visible light illumination. The photocatalytic efficiency of the mesoporous titania anatase-brookite photocatalyst dramatically increased with the addition of the C, N and S non-metal, achieving complete degradation (?100%) of MC-LR. The results demonstrate the advantages of the synthetic approach and the great potential of the visible light activated C, N, and S doped titania photocatalysts for the treatment of organic micropollutants in contaminated waters under visible light. PMID:25238189

El-Sheikh, Said M; Zhang, Geshan; El-Hosainy, Hamza M; Ismail, Adel A; O'Shea, Kevin E; Falaras, Polycarpos; Kontos, Athanassios G; Dionysiou, Dionysios D

2014-09-15

130

Enhanced performance of lithium sulfur battery with polypyrrole warped mesoporous carbon/sulfur composite  

NASA Astrophysics Data System (ADS)

A sulfur cathode is designed with three-dimensional (3D) cubic mesoporous carbon CMK-8 as the matrix of sulfur, and polypyrrole (PPY) as the wrapping layer. CMK-8 provides perfect 3D conductive network. Furthermore, PPY is coated onto the surface of CMK-8/sulfur (CMK-8/S) composite to inhibit the migration of lithium polysulfide and offer better lithium ion conductive channels. The microstructure and electrochemical performance of the PPY@CMK-8/sulfur (PPY@CMK-8/S) cathode are investigated systematically. The results show that PPY layer with about 50 nm thickness is coated uniformly on the surface of CMK-8/S. The Li-S battery with PPY@CMK-8/S as cathode material presents a discharge capacity of 937.8 mAh g-1 at 20 cycles and is stabilized at about 860 mAh g-1 after 100 cycles at 0.2C.

Ma, Guoqiang; Wen, Zhaoyin; Jin, Jun; Lu, Yan; Rui, Kun; Wu, Xiangwei; Wu, Meifen; Zhang, Jingchao

2014-05-01

131

Adsorption process of methyl orange dye onto mesoporous carbon material-kinetic and thermodynamic studies.  

PubMed

The mesoporous carbon CMK-3 adsorbent was prepared, characterized, and used for the removal of anionic methyl orange dye from aqueous solution. Adsorption experiments were carried out as batch studies at different contact time, pH, initial dye concentration, and salt concentration. The dye adsorption equilibrium was rapidly attained after 60 min of contact time. Removal of dye in acidic solutions was better than in basic solutions. The adsorption of dye increased with increasing initial dye concentration and salt concentration. The equilibrium data were analyzed by the Langmuir and Freundlich models, which revealed that Langmuir model was more suitable to describe the methyl orange adsorption than Freundlich model. Experimental data were analyzed using pseudo-first-order and pseudo-second-order kinetic models. It was found that kinetics followed a pseudo-second-order equation. Thermodynamic study showed that the adsorption was a spontaneous and exothermic process. PMID:21798549

Mohammadi, Nourali; Khani, Hadi; Gupta, Vinod Kumar; Amereh, Ehsanollah; Agarwal, Shilpi

2011-10-15

132

Adsorption kinetics of NO on ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC)  

NASA Astrophysics Data System (ADS)

Ordered mesoporous carbon (OMC) and cerium-containing OMC (Ce-OMC) were prepared using evaporation-induced self-assembly (EISA) method and used to adsorb NO. N2 sorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to confirm their structures. The results showed that the ordered and uniform structures were successfully synthesized and with the introduction of cerium pore properties were not significantly changed. The NO adsorption capacity of OMC was two times larger than that of activated carbon (AC). With the introduction of cerium both the adsorption capacity and the adsorption rate were improved. The effects of residence time and oxygen concentration on NO adsorption were also investigated. Oxygen played an important role in the NO adsorption (especially in the form of chemisorption) and residence time had small influence on the NO adsorption capacity. The NO adsorption kinetics was analyzed using pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion models. The results indicated that the NO adsorption process can be divided into rapid adsorption period, slow adsorption period, and equilibrium adsorption period. The pseudo-second-order model was the most suitable model for NO adsorption on OMC and Ce-OMC. The rate controlling step was the intraparticle diffusion together with the adsorption reaction.

Chen, Jinghuan; Cao, Feifei; Chen, Songze; Ni, Mingjiang; Gao, Xiang; Cen, Kefa

2014-10-01

133

Carbon dioxide adsorption on amine-impregnated mesoporous materials prepared from spent quartz sand.  

PubMed

Mesoporous MCM-41 was synthesized using cetyltrimethyl ammonium bromide (CTAB) as a cationic surfactant and spent quartz sand as the silica source. Modification of the mesoporous structure to create an absorbent was then completed using 3-aminopropyltrimethoxysilane. Amine-Quartz-MCM (The A-Q-MCM) adsorbents were then characterized by N2 adsorption/desorption, elemental analysis (EA), X-ray fluorescence (XRF), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), as well as the carbon dioxide (CO2) adsorption/desorption performance. In this study, spent quartz sand was utilized to synthesize Quartz-MCM (Q-MCM) and the amine functionalized material, A-Q-MCM, which exhibited a higher uptake of CO2 at room temperature compared with the nongrafted material. The results showed that Q-MCM is similar to MCM-41 synthesized using commercial methods. The surface area, pore volume, and pore diameter were found to be as high as 1028 m2/g, 0.907 cm3/g, and 3.04 nm, respectively. Under the condition of CO2 concentration of 5000 ppm, retention time of 50 cc/min, and the dosage of 1 g/cm3, the mean adsorption capacity of CO2 onto A-Q-MCM was about 89 mg/g, and the nitrogen content of A-Q-MCM was 2.74%. The adsorption equilibrium was modeled well using a Freundlich isotherm. Implications: In this study, spent quartz sand was utilized to synthesize Q-MCM. The amine functionalized material exhibited a higher uptake of CO2 at room temperature compared with the nongrafted material. The results showed that Q-MCM is similar to MCM-41 synthesized using commercial methods. The adsorption equilibrium was modeled well using a Freundlich isotherm. PMID:25122956

Su, Yiteng; Peng, Lihong; Shiue, Angus; Hong, Gui-Bing; Qian, Zhang; Chang, Chang-Tang

2014-07-01

134

Reaction mechanism of all-solid-state lithium-sulfur battery with two-dimensional mesoporous carbon electrodes  

NASA Astrophysics Data System (ADS)

The reaction mechanism of all-solid-state lithium-sulfur batteries was studied by small- and wide-angle X-ray scattering. The results revealed that sulfur deposited in the electrode framework has a random distribution on the carbon wall of the highly ordered mesoporous carbon, CMK-3. Heat treatment complicated carbon surfaces with attached sulfur and improved the reversible charge-discharge reaction. Two Li2S phases formed during the discharge reaction; one of them participates in the reversible battery reactions.

Nagao, Miki; Imade, Yuki; Narisawa, Haruto; Watanabe, Ryota; Yokoi, Toshiyuki; Tatsumi, Takashi; Kanno, Ryoji

2013-12-01

135

Preparation and drug release behavior of temperature-responsive mesoporous carbons  

SciTech Connect

A temperature-responsive composite based on poly (N-isopropylacrylamide) (PNIPAAm) and ordered mesoporous carbons (OMCs) has been successfully prepared by a simple wetness impregnation technique. The structures and properties of the composite were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), N{sub 2} sorption, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The results showed that the inclusion of PNIPAAm had not greatly changed the basic ordered pore structure of the OMCs. Ibuprofen (IBU) was selected as model drug, and in vitro test of IBU release exhibited a temperature-responsive controlled release delivery. - Graphical abstract: The bands located at 1650 and 1549 cm{sup -1} could be assigned to C=O stretching and N-H bending vibrations for polymer PNIPAAm (a). The bands at 1388 and 1369 cm{sup -1} were due to isopropyl group, and the band at 1459 cm{sup -1} was related to the bending vibration of C-H (a). For the PNIPAAm/OMCs composite, the characteristic bands of polymer were still observed besides those for carbon materials and the bands at around 1585 cm{sup -1} and a broad band at about 1100 cm{sup -1} were characteristics for the carbon materials(c). In addition, little shifts of C=O and N-H bands compared to the pure PNIPAAm were also observed (b), indicating a weak interaction between the polymer and carbon material. These results could be a proof that the PNIPAAm has been incorporated into the carbon material. Highlights: > A temperature-responsive PNIPAAm/OMCs composite was successfully synthesized by a simple wetness impregnation technique for the first time. > The inclusion of PNIPAAm had not greatly changed the basic ordered pore structure of the OMCs. > In vitro test of IBU release exhibited a temperature-responsive controlled release delivery.

Wang Xiufang [College of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006 (China); Liu Ping [School of Chemistry and Chemical Engineering, Henan Institute of Science and Technology, Xinxiang 453003 (China); Tian Yong, E-mail: fengshoutian@hotmail.com [College of Pharmacy, Guangdong Pharmaceutical University, Guangzhou 510006 (China)

2011-06-15

136

Effects of CO 2 activation on porous structures of coconut shell-based activated carbons  

NASA Astrophysics Data System (ADS)

In this paper, textural characterization of an activated carbon derived from carbonized coconut shell char obtained at carbonization temperature of 600 °C for 2 h by CO 2 activation was investigated. The effects of activation temperature, activation time and flow rate of CO 2 on the BET surface area, total volume, micropore volume and yield of activated carbons prepared were evaluated systematically. The results showed that: (i) enhancing activation temperature was favorable to the formation of pores, widening of pores and an increase in mesopores; (ii) increasing activation time was favorable to the formation of micropores and mesopores, and longer activation time would result in collapsing of pores; (iii) increasing flow rate of CO 2 was favorable to the reactions of all active sites and formation of pores, further increasing flow rate of CO 2 would lead carbon to burn out and was unfavorable to the formation of pores. The degree of surface roughness of activated carbon prepared was measured by the fractal dimension which was calculated by FHH (Frenkel-Halsey-Hill) theory. The fractal dimensions of activated carbons prepared were greater than 2.6, indicating the activated carbon samples prepared had very irregular structures, and agreed well with those of average micropore size.

Guo, Shenghui; Peng, Jinhui; Li, Wei; Yang, Kunbin; Zhang, Libo; Zhang, Shimin; Xia, Hongying

2009-07-01

137

Facile synthesis of yolk-shell magnetic mesoporous carbon microspheres for efficient enrichment of low abundance peptides.  

PubMed

Magnetic mesoporous carbon microspheres with a yolk-shell structure (YSMMCS) have been prepared via a new in situ carbon source strategy. The material was fabricated by two shells coated onto the Fe3O4 particles; the inner dense and thick silica shell could protect the magnetic core from harsh acidic solvents as well as induce the void between the core and the outer shell for the yolk-shell structure, while the outer organosilica shell was used as the template and carbon source for in situ preparation of a carbon shell with mesoporous structure. A C18-alkyl chain was incorporated in situ as the carbon precursor efficiently, avoiding the conventional infiltration step, which was very difficult to manipulate and time-consuming with the possibility of losing the carbon precursor. The resulting yolk-shell magnetic mesoporous carbon microspheres exhibited a high surface area (273.15 m(2) g(-1)), a large pore volume (0.31 cm(3) g(-1)), and a strong magnetic response (a saturation magnetization value of 34.57 emu g(-1)). As a result of the void between the core and the outer shell and the ?-? stacking effect, adsorption capacity reached 191.64 mg g(-1) by using Rhodamine B as a standard analyte, indicating the great potential application of the material as drug carriers. Owing to the inherent hydrophobicity and high surface area, the composite material showed better performance in the enrichment of peptides than a magnetic mesoporous silica material (Fe2O3@nSiO2@mSiO2). According to the LC-MS/MS results, about 51 and 29 nonredundant peptides were identified from tryptic digests of 5 nM BSA. Additionally, taking advantage of the mesoporous structure and strong magnetic response, the material was utilized to selectively extract low abundance endogenous peptides from human serum in the presence of high abundance proteins. Based on the LC-MS/MS results, 962 endogenous peptides were obtained by 2.5 mg YSMMCS relative to 539 endogenous peptides by 5 mg Fe2O3@nSiO2@mSiO2, confirming the outstanding performance of YSMMCS in peptidome analysis. PMID:24061763

Wan, Hao; Qin, Hongqiang; Xiong, Zhichao; Zhang, Weibing; Zou, Hanfa

2013-11-21

138

Mesoporous carbon-containing MoS 2 materials formed from the in situ decomposition of tetraalkylammonium thiomolybdates  

Microsoft Academic Search

Molybdenum disulfide with unique mesoporous structure was synthesized from tetraalkylammonium thiometallate precursors in situ decomposed in a batch reactor in the presence of dibenzothiophene (DBT). The precursors used in this study were tetraalkylammonium thiomolybdates with alkyl groups ranging from propyl to octyl. Molybdenum disulfide thus prepared presents high surface area (from 255 up to 329m2\\/g), high content of carbon (C\\/Mo=2.7–4.0)

Gabriel Alonso; Gilles Berhault; Eric Rivera; Sergio Fuentes; Russell R Chianelli

2003-01-01

139

Facile fabrication of dye-sensitized solar cells utilizing carbon nanotubes grown over 2D hexagonal bimetallic ordered mesoporous materials  

NASA Astrophysics Data System (ADS)

High-surface area and well-ordered mesoporous Fe incorporated SBA-15 (Fe-SBA-15), Fe-Cr incorporated SBA-15 (Fe-Cr-SBA-15) and Cr incorporated SBA-15 (Cr-SBA-15) catalysts are synthesized following a controlled post synthesis grafting process. The activities of all the catalysts are tested systematically and quantitatively towards the production of carbon nanotubes (CNTs) by chemical vapour deposition. In order to obtain CNTs with high quality and quantity, the parameters like temperature, reaction time and gas flow rate are optimized. Under optimum conditions, the Fe-Cr-SBA-15 catalyst is produced with high yield and uniform diameter of CNTs. The transmission electron microscopy result reveals high purity and well-graphitized structure of CNTs. The synthesized CNTs are used as counter electrode material for dye-sensitized solar cells (DSSCs). The CNTs based counter electrode shows good chemical stability, lower charge-transfer resistance and higher electrocatalytic activity towards I3-/I- redox reaction than that of platinum (Pt) counter electrode. The energy conversion efficiency of the CNTs counter electrode based DSSCs reaches 8.86% under irradiation with a simulated solar light intensity of 100 mW cm-2. The results prove that CNTs are one of the suitable candidates for Pt free counter electrode for DSSCs.

Balamurugan, J.; Thangamuthu, R.; Pandurangan, A.; Jayachandran, M.

2013-03-01

140

Ammonia-assisted semicarbonization: a simple method to introduce micropores without damaging a 3D mesoporous carbon nanonetwork structure.  

PubMed

A simple and effective way to introduce micropores into skeleton of carbon aerogel (CA) without damaging its unique 3D mesoporous nanonetwork has been successfully developed by NH3-assisted semicarbonization. During the NH3-assisted semicarbonization process, nitrogen functional groups with high thermo-decomposable ability like pyrrolic/pyridine and pyridinic can be introduced into the semicarbonized aerogel framework by substituting oxygen functional groups with low thermo-decomposable ability like C?O quinone-type groups and then escape from the resultant CA framework during the subsequent carbonization, thus forming abundant micropores inside carbon framework under the circumstance of keeping wonderful stability of mesoporous nanonetwork structure. Compared with the traditional CA without NH3 assistance during semicarbonization, the as-prepared novel CA represents a much higher surface area (1100 vs 620 m(2) g(-1)) and a compatible mesopore structure. Meanwhile, such a NH3 treatment confers many useful nitrogen functional groups on the nanonetwork framework. The novel CA is then used as electrode material of supercapacitors and shows a much higher capacitance and comparable high capacitance retention as compared with the traditional CA. PMID:25035264

Yang, Xiaoqing; Zhang, Guoqing; Zhong, Meiling; Wu, Dingcai; Fu, Ruowen

2014-08-01

141

Activated carbon from biomass  

NASA Astrophysics Data System (ADS)

Activated carbon are unique and versatile adsorbents having extended surface area, micro porous structure, universal adsorption effect, high adsorption capacity and high degree of surface reactivity. Activated carbons are synthesized from variety of materials. Most commonly used on a commercial scale are cellulosic based precursors such as peat, coal, lignite wood and coconut shell. Variation occurs in precursors in terms of structure and carbon content. Coir having very low bulk density and porous structure is found to be one of the valuable raw materials for the production of highly porous activated carbon and other important factor is its high carbon content. Exploration of good low cost and non conventional adsorbent may contribute to the sustainability of the environment and offer promising benefits for the commercial purpose in future. Carbonization of biomass was carried out in a horizontal muffle furnace. Both carbonization and activation were performed in inert nitrogen atmosphere in one step to enhance the surface area and to develop interconnecting porosity. The types of biomass as well as the activation conditions determine the properties and the yield of activated carbon. Activated carbon produced from biomass is cost effective as it is easily available as a waste biomass. Activated carbon produced by combination of chemical and physical activation has higher surface area of 2442 m2/gm compared to that produced by physical activation (1365 m2/gm).

Manocha, S.; Manocha, L. M.; Joshi, Parth; Patel, Bhavesh; Dangi, Gaurav; Verma, Narendra

2013-06-01

142

Facile synthesis of gradient mesoporous carbon monolith based on polymerization-induced phase separation  

NASA Astrophysics Data System (ADS)

In this paper, a gradient mesoporous carbon (GMC) monolith derived from the mixtures of phenolic resin (PF) and ethylene glycol (EG) was prepared by a facile route based on polymerization-induced phase separation under temperature gradient (TG). A graded biphasic structure of PF-rich and EG-rich phases was first formed in preform under a TG, and then the preform was pyrolyzed to obtain the GMC monolith. The TG is mainly induced by the thermal resistance of the preferential phase separation layer at high temperature region. The pore structure of the monolith changes gradually along the TG direction. When the TG varies from 58°C to 29°C, the pore size, apparent porosity and specific surface area of the monolith range respectively from 18 nm to 83 nm, from 32% to 39% and from 140.5 m2/g to 515.3 m2/g. The gradient porous structure of the monolith is inherited from that of the preform, which depends on phase separation under TG in the resin mixtures. The pyrolysis mainly brings about the contraction of the pore size and wall thickness as well as the transformation of polymerized PF into glassy carbon.

Xu, Shunjian; Luo, Yufeng; Zhong, Wei; Xiao, Zonghu; Luo, Yongping; Ou, Hui; Zhao, Xing-Zhong

2014-06-01

143

Comparison on pore development of activated carbon produced from palm shell and coconut shell  

Microsoft Academic Search

A series of experiments were conducted to compare the pore development in palm-shell and coconut-shell-based activated carbons produced under identical experimental conditions. Carbonization and activation processes were carried out at 850 °C using a fluidized bed reactor. Within the range of burn-off studied, at any burn-off, the micropore and mesopore volumes created in palm-shell-based activated carbon were always higher than

Wan Mohd Ashri Wan Daud; Wan Shabuddin Wan Ali

2004-01-01

144

Direct tri-constituent co-assembly of highly ordered mesoporous carbon counter electrode for dye-sensitized solar cells.  

PubMed

Controlling over ordered porosity by self-assembly is challenging in the area of materials science. Materials with highly ordered aperture are favorable candidates in catalysis and energy conversion device. Here we describe a facile process to synthesize highly ordered mesoporous carbon (OMC) by direct tri-constituent co-assembly method, which uses resols as the carbon precursor, tri-block copolymer F127 as the soft template and tetraethoxysilane (TEOS) as the inorganic precursor. The obtained products are characterized by small-angle X-ray diffraction (SAXD), Brunauer-Emmett-Teller (BET) nitrogen sorption-desorption measurement and transmission electron microscope (TEM). The results indicate that the OMC possesses high surface areas of 1209 m(2) g(-1), homogeneous pore size of 4.6 nm and a large pore volume of 1.65 cm(3) g(-1). The advantages of high electrochemical active surface area and favorable accessible porosity of OMC benefit the catalysis of I(3)(-) to I(-). As a result, the OMC counter electrode displays a remarkable property when it was applied in dye-sensitized solar cells (DSSCs). For comparison, carbon black (CB) counter electrode and Pt counter electrode have also been prepared. When these different counter electrodes were applied for dye-sensitized solar cells (DSSCs), the power-conversion efficiency (?) of the DSSCs with CB counter electrode are measured to be 5.10%, whereas the corresponding values is 6.39% for the DSSC with OMC counter electrode, which is comparable to 6.84% of the cell with Pt counter electrode under the same experimental conditions. PMID:23165970

Peng, Tao; Sun, Weiwei; Sun, Xiaohua; Huang, Niu; Liu, Yumin; Bu, Chenghao; Guo, Shishang; Zhao, Xing-Zhong

2013-01-01

145

Direct tri-constituent co-assembly of highly ordered mesoporous carbon counter electrode for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Controlling over ordered porosity by self-assembly is challenging in the area of materials science. Materials with highly ordered aperture are favorable candidates in catalysis and energy conversion device. Here we describe a facile process to synthesize highly ordered mesoporous carbon (OMC) by direct tri-constituent co-assembly method, which uses resols as the carbon precursor, tri-block copolymer F127 as the soft template and tetraethoxysilane (TEOS) as the inorganic precursor. The obtained products are characterized by small-angle X-ray diffraction (SAXD), Brunauer-Emmett-Teller (BET) nitrogen sorption-desorption measurement and transmission electron microscope (TEM). The results indicate that the OMC possesses high surface areas of 1209 m2 g-1, homogeneous pore size of 4.6 nm and a large pore volume of 1.65 cm3 g-1. The advantages of high electrochemical active surface area and favorable accessible porosity of OMC benefit the catalysis of I3- to I-. As a result, the OMC counter electrode displays a remarkable property when it was applied in dye-sensitized solar cells (DSSCs). For comparison, carbon black (CB) counter electrode and Pt counter electrode have also been prepared. When these different counter electrodes were applied for dye-sensitized solar cells (DSSCs), the power-conversion efficiency (?) of the DSSCs with CB counter electrode are measured to be 5.10%, whereas the corresponding values is 6.39% for the DSSC with OMC counter electrode, which is comparable to 6.84% of the cell with Pt counter electrode under the same experimental conditions.

Peng, Tao; Sun, Weiwei; Sun, Xiaohua; Huang, Niu; Liu, Yumin; Bu, Chenghao; Guo, Shishang; Zhao, Xing-Zhong

2012-12-01

146

Synthesis of nitrogen-rich mesoporous carbon nitride with tunable pores, band gaps and nitrogen content from a single aminoguanidine precursor.  

PubMed

Highly ordered mesoporous carbon nitride (CN) with an extremely high nitrogen content and tunable pore diameters was synthesized by using a new precursor with a high nitrogen content, aminoguanidine hydrochloride and mesoporous silica SBA-15 with different pore diameters as hard templates. Surprisingly, the N/C ratio of the prepared mesoporous CN (MCN-4: 1.80) was considerably higher than that of the theoretically predicted C(3)N(4) nanostructures (1.33). This is mainly due to the fact that the CN precursor easily undergoes polymerization at high temperature and affords a highly stable polymer composed of a diamino-s-tetrazine moiety with a six-membered aromatic ring containing six nitrogen atoms that are linked trigonally with the nitrogen atoms. The obtained materials were thoroughly characterized by means of XRD, nitrogen adsorption, high resolution TEM, electron energy loss spectra, high resolution SEM, X-ray photoelectron spectroscopy, FTIR, and C, N, O, and S analysis. The results show that the MCN-4 materials possess a well-ordered mesoporous structure similar to SBA-15 with a high specific surface area and tunable band gap in the range of 2.25-2.49 eV. Interestingly, the pore diameter of the materials can be finely tuned from 3.1-5.8 nm by increasing the pore diameter of the hard-template SBA-15. The reaction temperature plays a critical role for the formation of MCN, and we found that 400 °C is the best condition to obtain MCN-4 with a high nitrogen content. We have further investigated the catalytic application of the MCN-4 materials towards Friedel-Crafts hexanoylation of benzene and compared the results with the mesoporous CN with less nitrogen content (MCN-1) and nonporous CN. Among the materials studied, MCN-4 showed the highest activity, affording a high yield of hexanophenone within a few hours, which is mainly due to the presence of free amine groups on the wall structure of MCN-4. PMID:22389323

Talapaneni, Siddulu N; Mane, Gurudas P; Mano, Ajayan; Anand, Chokkalingam; Dhawale, Dattatray S; Mori, Toshiyuki; Vinu, Ajayan

2012-04-01

147

Mesoporous MgTa2O6 thin films with enhanced photocatalytic activity: On the interplay between crystallinity and mesostructure  

PubMed Central

Summary Ordered mesoporous, crystalline MgTa2O6 thin films with a mesoscopic nanoarchitecture were synthesized by evaporation-induced self-assembly (EISA) in combination with a sol–gel procedure. Utilization of novel templates, namely the block copolymers KLE (poly(ethylene-co-butylene)-b-poly(ethylene oxide)) and PIB6000 (CH3C(CH3)2(CH2C(CH3)2)107CH2C(CH3)2C6H4O(CH2CH2O)100H), was the key to achieving a stable ordered mesoporous structure even upon crystallization of MgTa2O6 within the mesopore walls. The effect of the calcination temperature on the ability of the mesoporous films to assist the photodegradation of rhodamine B in water was studied. As a result, two maxima in the photocatalytic activity were identified in the calcination temperature range of 550–850 °C, peaking at 700 °C and 790 °C, and the origin of this was investigated by using temperature-dependent X-ray scattering. Optimal activity was obtained when the mesoporous film was heated to 790 °C; at this temperature, crystallinity was significantly high, with MgTa2O6 nanocrystals of 1.6 nm in size (averaged over all reflections), and an ordered mesoporous structure was maintained. When considering the turnover frequency of such photocatalysts, the optimized activity of the present nanoarchitectured MgTa2O6 thin film was ca. four times that of analogous anatase TiO2 films with ordered mesopores. Our study demonstrated that high crystallinity and well-developed mesoporosity have to be achieved in order to optimize the physicochemical performance of mesoporous metal-oxide films. PMID:22428103

Wu, Jin-Ming; Djerdj, Igor; von Graberg, Till

2012-01-01

148

Platinum particles supported on mesoporous carbons: fabrication and electrocatalytic performance in methanol-tolerant oxygen-reduction reactions  

NASA Astrophysics Data System (ADS)

In this report, we describe the preparation and electrochemical characterization of a Pt electrocatalyst, which was synthesized from hexachloroplatinic acid, using the incipient wetness impregnation method. This carbon mesoporous materials (Pt-CMMs) electrocatalyst was used for catalyzing the oxidation of methanol and its oxygen-reduction reaction. The electrocatalytic oxidation of methanol was studied using linear-sweep voltammograms (LSV), polarization and chronoamperometric measurements. Phase characterizations and morphological analyses were performed using 3D excitation-emission fluorescent matrix (EEFM) spectroscopy, UV-Vis absorption measurements, and X-ray diffraction (XRD) and environmental scanning electron microscopy (ESEM) techniques; the ESEM system was equipped with an energy-dispersive spectrometer (EDS). The oxidation capacity measured using a LSV might explain the high activity exhibited by the Pt-CMM electrocatalysts in methanol-tolerant oxygen reduction, and the results demonstrated that the potential and current density of the main reaction peak of the Pt-CMMs electrocatalyst changed during the reaction. Moreover, EEFM spectroscopy and XRD were determined to be appropriate and effective methods for characterizing Pt clusters that enhance their intrinsic emission from Pt-CMMs electrocatalysts in electrocatalytic-treatment systems. Furthermore, the ESEM-EDS results showed that fresh Pt nanoparticles were highly dispersed on CMMs and featured a 20 nm diameter and a narrow particle-size distribution.

Dong, Cheng-Di; Chen, Chiu-Wen; Chen, Chih-Feng; Hung, Chang-Mao

2014-08-01

149

Challenges in fabrication of mesoporous carbon films with ordered cylindrical pores via phenolic oligomer self-assembly with triblock copolymers.  

PubMed

Mesoporous phenol formaldehyde (PF) polymer resin and carbon films are prepared by a solution self-assembly of PF oligomers with amphiphilic triblock copolymers. After thermopolymerization of the PF to cross-link the network, the films show an ordered morphology as determined by X-ray diffraction and grazing incidence small-angle X-ray scattering (GISAXS). Our results show that the amphiphilic triblock copolymer template greatly influences the stability of the final porous mesostructures. The pyrolysis of the two-dimensional (2-D) hexagonal films with p6mm symmetry templated by Pluronic F127 yields a disordered porous structure following the template removal. Conversely, films templated by Pluronic P123 can exhibit well-ordered cylindrical pores after the template removal, but the solution composition range to yield ordered cylindrical mesopores is significantly reduced (nearly 70%) for thin films in comparison to bulk powders. We propose two dominant difficulties in fabricating well-ordered cylindrical mesopores in films: first, the stress from contraction during the pyrolysis can lead to a collapse of the mesostructure if the wall thickness is insufficient, and second, the surface wetting behavior in thin films leads to a small compositional range. PMID:20000606

Song, Lingyan; Feng, Dan; Fredin, Nathaniel J; Yager, Kevin G; Jones, Ronald L; Wu, Quanyan; Zhao, Dongyuan; Vogt, Bryan D

2010-01-26

150

Improved electrochemical performance of SnO2-mesoporous carbon hybrid as a negative electrode for lithium ion battery applications.  

PubMed

To utilize the high specific capacity of SnO2 as an anode material in lithium-ion batteries, one has to overcome its poor cycling performance and rate capability, which result from large volume expansion (?300%) of SnO2 during charging-discharging cycles. Hence, to accommodate the volume change during cycling, SnO2 nanoparticles of 6 nm diameter were synthesized specifically only on the outer surface of the mesopores, present within mesoporous carbon (CMK-5) particles, resulting in an effective buffering layer. To that end, the synthesis process first involves the formation of 3.5 nm SnO2 nanoparticles inside the mesopores of mesoporous silica (SBA-15), the latter being used as a template subsequently to obtain SnO2-CMK-5 hybrid particles. SnO2-CMK-5 exhibits superior rate capabilities, e.g. after 30 cycles, a specific discharge capacity of 598 mA h g(-1), at a current density of 178 mA g(-1). Electrochemical impedance spectroscopy reveals that the SnO2-CMK-5 electrode undergoes a significant reduction in solid-electrolyte interfacial and charge transfer resistances, with a simultaneous increase in the diffusion coefficient of lithium ions, all these in comparison to an electrode made of only SnO2 nanoparticles. This enhances the potential of using the SnO2-CMK-5 hybrid as a negative electrode, in terms of improved discharge capacity and cycling stability, compared to other electrodes, such as only SnO2 or only CMK-5. PMID:24576943

Srinivasan, N R; Mitra, Sagar; Bandyopadhyaya, Rajdip

2014-04-14

151

Understanding activated carbons  

SciTech Connect

It would be fair to say that most chemical industry professionals can explain the differences between adsorption and absorption. But when asked which type of activated carbon would be best suited for a particular application, few chemists or chemical engineers would be able to identify what properties to look for. Activated carbon is used in a wide variety of applications such as purification or recovery of chemical products, catalysis or catalyst supports, and various environmental applications such as VPC abatement and wastewater purification. With such broad used in industry, it is critical for engineers and chemists to understand the differences between activated carbons in order to obtain the best performance from their processes.

Boppart, S.; Ingle, L.; Potwora, R.J.; Rester, D.O. [NORIT Americas Inc., Atlanta, GA (United States)

1996-09-01

152

Fabrication of 2D ordered mesoporous carbon nitride and its use as electrochemical sensing platform for H2O2, nitrobenzene, and NADH detection.  

PubMed

Two-dimensional ordered mesoporous carbon nitride (OMCN) has been successfully prepared for the first time using SBA-15 mesoporous silica and melamine as template and precursor respectively, by a nano hard-templating approach. A series of OMCN-x samples with different pyrolysis temperatures have been reported. The formation of these composite materials was verified by detailed characterization (e.g., Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, N2 adsorption, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy). The results showed that the materials were structurally well ordered with two-dimensional porous structure, high surface area and large pore volume. The influence of BET surface area and different amounts of N-bonding configurations formed at different pyrolysis temperatures of OMCN-x for the electrocatalysis towards hydrogen peroxide, nitrobenzene, and nicotinamide adenine dinucleotide were investigated in detail. Results indicated that OMCN treated at 800°C with largest BET surface area and highest amounts of pyrindinic N showed improved electrocatalytic activity for H2O2, nitrobenzene, and NADH in neutral solution. PMID:24144555

Zhang, Yufan; Bo, Xiangjie; Nsabimana, Anaclet; Luhana, Charles; Wang, Guang; Wang, Huan; Li, Mian; Guo, Liping

2014-03-15

153

High pseudocapacitance of MnO2 nanoparticles in graphitic disordered mesoporous carbon at high scan rates  

SciTech Connect

Nanocomposites composed of MnO{sub 2} and graphitic disordered mesoporous carbon (MnO{sub 2}/C) were synthesized for high total specific capacitance and redox pseudocapacitance (C{sub MnO{sub 2}}) at high scan rates up to 200 mV s{sup -1}. High resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy (EDX) demonstrated that MnO{sub 2} nanodomains were highly dispersed throughout the mesoporous carbon structure. According to HRTEM and X-ray diffraction (XRD), the MnO{sub 2} domains are shown to be primarily amorphous and less than 5 nm in size. For these composites in aqueous 1 M Na{sub 2}SO{sub 4} electrolyte, C{sub MnO{sub 2}} reached 500 F/g{sub MnO{sub 2}} at 2 mV s{sup -1} for 8.8 wt% MnO{sub 2}. A capacitance fade of only 20% over a 100-fold change in scan rate was observed for a high loading of 35 wt% MnO{sub 2} with a C{sub MnO{sub 2}} of 310 F/g{sub MnO{sub 2}} at the highest scan rate of 200 mV s{sup -1}. The high electronic conductivity of the graphitic 3D disordered mesoporous carbon support in conjunction with the thin MnO{sub 2} nanodomains facilitate rapid electron and ion transport offering the potential of improved high power density energy storage pseudocapacitors.

Dai, Sheng [ORNL; Patel, Mehul [University of Texas, Austin; Wang, Xiqing [ORNL; Slanac, Daniel A [ORNL; Ferrer, Domingo [University of Texas, Austin; Johnston, Keith [University of Texas, Austin

2012-01-01

154

High psedocapacitance of MnO2 nanoparticles in graphitic disordered mesoporous carbon at high scan rates  

SciTech Connect

Nanocomposites composed of MnO{sub 2} and graphitic disordered mesoporous carbon (MnO{sub 2}/C) were synthesized for high total specific capacitance and redox pseudocapacitance (C{sub MnO{sub 2}}) at high scan rates up to 200 mV s{sup -1}. High resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy (EDX) demonstrated that MnO{sub 2} nanodomains were highly dispersed throughout the mesoporous carbon structure. According to HRTEM and X-ray diffraction (XRD), the MnO{sub 2} domains are shown to be primarily amorphous and less than 5 nm in size. For these composites in aqueous 1 M Na{sub 2}SO{sub 4} electrolyte, C{sub MnO{sub 2}} reached 500 F/g{sub MnO{sub 2}} at 2 mV s{sup -1} for 8.8 wt% MnO{sub 2}. A capacitance fade of only 20% over a 100-fold change in scan rate was observed for a high loading of 35 wt% MnO{sub 2} with a C{sub MnO{sub 2}} of 310 F/g{sub MnO{sub 2}} at the highest scan rate of 200 mV s{sup -1}. The high electronic conductivity of the graphitic 3D disordered mesoporous carbon support in conjunction with the thin MnO{sub 2} nanodomains facilitate rapid electron and ion transport offering the potential of improved high power density energy storage pseudocapacitors.

Dai, Sheng [ORNL; Patel, Mehul [University of Texas, Austin; Wang, Xiqing [ORNL; Slanac, Daniel A [ORNL; Ferrer, Domingo [University of Texas, Austin; Johnston, Keith [University of Texas, Austin; Stevenson, Keith J [ORNL

2012-01-01

155

One-pot hydrothermal synthesis of mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide hybrid material and its enhanced photocatalytic activity.  

PubMed

We successfully synthesized mesoporous Zn(x)Cd(1-x)S/reduced graphene oxide (Z(x)CSG) hybrid materials as photocatalysts using a facile one-pot hydrothermal reaction, in which graphene oxide (GO) was easily reduced (RGO), and simultaneously Zn(x)Cd(1-x)S (Z(x)CS) nanoparticles (NPs) with a mesoporous structure were uniformly dispersed on the RGO sheets. By well tuning the band gap from 3.42 to 2.21 eV by changing the molar ratio of Zn/Cd (or Zn content), Z(x)CSG with an optimal zinc content has been found to have a significant absorption in the visible light (VL) region. In addition, under VL irradiation (? > 420 nm), Z(x)CSG also showed zinc content-dependent photocatalytic efficiencies for the degradation of methylene blue (MB). Our findings are that, among Z(x)CSG, Z(0.4)CSG displayed not only a superior photodegradation efficiency of MB (98%), but also good removal efficiency of total organic carbon (TOC) (67%). Furthermore, Z(0.4)CSG had a high photocatalytic stability, and could be used repeatedly. The enhanced photocatalytic activity for Z(0.4)CSG could be attributed to a synergistic effect between mesoporous Z(x)CS NPs and RGO, including the optimal band gap and the moderate conduction band position for ZxCS (compared to CdS), efficient separation and transfer ability of photogenerated electron/hole pairs in the presence of RGO sheets, and relatively high surface area for both mesoporous Z(x)CS NPs and RGO. PMID:25019939

Wang, Xinwei; Tian, Hongwei; Cui, Xiaoqiang; Zheng, Weitao; Liu, Yichun

2014-09-14

156

Pore size effects on the sorption of supercritical carbon dioxide in mesoporous CPG-10 silica  

SciTech Connect

Excess sorption isotherms of supercritical carbon dioxide in mesoporous CPG-10 silica glasses with nominal pore sizes of 75 (7.5 nm) and 350 (35 nm) were measured gravimetrically at 35 C and 50 C and pressures of 0-200 bar. Formation of broad maxima in the excess sorption was observed at fluid densities below the bulk critical density. Positive values of excess sorption were measured at bulk densities below about 0.65-0.7 g/cm3, whereas zero and negative values were obtained at higher densities, indicating that the interfacial fluid becomes less dense than the corresponding bulk fluid at high fluid densities. A shift of the excess sorption peak position to higher fluid density is found with increasing pore width. The excess sorption of CO2 normalized to the specific surface area is higher for the 35 nm pore size material, suggesting pore confinement effects. Conversely, the pore volume normalized excess sorption is higher for the 7.5 nm pore size material. Assessment of mean pore density reveals regions of constant pore fluid density, located between the excess sorption peak and the adsorption/depletion transition. Both materials exhibit such regions of constant mean pore fluid density as a function of bulk CO2 density at the lower temperature of 35 C, but not at 50 C. The results of this study suggest that the CO2 storage capacity in quartz-rich reservoirs is higher for sites with low temperature and rock textures characterized by narrow pores with high surface to volume ratios.

Rother, Gernot [ORNL; Krukowski, Elizabeth G [ORNL; Wallacher, Dirk [Helmholtz-Zentrum Berlin; Grimm, Nico [Helmholtz-Zentrum Berlin; Bodnar, Robert J [ORNL; Cole, David [Ohio State University

2012-01-01

157

Smaller Pt particles supported on mesoporous bowl-like carbon for highly efficient and stable methanol oxidation and oxygen reduction reaction  

NASA Astrophysics Data System (ADS)

Bowl-like carbons (BLCs) with mesoporous structure are prepared using glucose as carbon source and solid core mesoporous shell silica spheres (SCMSSs) as templates. Pt particles are then loaded on the BLCs as electrocatalyst and used for both methanol oxidation and oxygen reduction reaction (ORR) in acidic media. Physical measurements display that the BLCs are formed due to flowing of melted glucose along the mesoporous shell of the SCMSSs. Moreover, the BLCs with high surface area (1108.3 m2 g-1), large pore volume (2.7 cm3 g-1) and mesoporous structure (9.4 nm in diameter) are beneficial for uniform dispersion and stable loading of smaller noble metal particles, and efficiently improve the mass transfer in catalytic reactions, compared to carbon powders. Cyclic voltammogram measurements show that the mass current densities on Pt/BLC electrocatalyst are 2.6 times (1846 mA mgPt-1) for methanol oxidation and 1.6 times (180.6 mA mgPt-1) for ORR as high as that of commercial Pt/C (TKK). Furthermore, the mesopores give Pt/BLC more electrocatalytic stability due to stronger physical interaction force.

Yan, Zaoxue; Zhang, Mingmei; Xie, Jimin; Wang, Hongen; Wei, Wei

2013-12-01

158

Adsorption of anionic and cationic dyes on ferromagnetic ordered mesoporous carbon from aqueous solution: equilibrium, thermodynamic and kinetics.  

PubMed

Ordered mesoporous carbon (Fe-CMK-3) with iron magnetic nanoparticles was prepared by a casting process via SBA-15 silica as template and anthracene as carbon source, was used as a magnetic adsorbent for the removal of anionic dye Orange II (O II) and cationic dye methylene blue (MB) from aqueous solution. TEM and magnetometer images showed that the iron magnetic nanoparticles were successfully embedded in the interior of the mesoporous carbon. The effect of various process parameters such as temperature (25-45°C), initial concentration (100-500 mg L(-1)) and pH (2-12) were performed. Equilibrium adsorption isotherms and kinetics were also studied. The equilibrium experimental data were analyzed by the Langmuir, Freundlich, Temkin and Redlich-Peterson model. The equilibrium data for two dyes adsorption was fitted to the Langmuir, and the maximum monolayer adsorption capacity for O II and MB dyes were 269 and 316 mg g(-1), respectively. Pseudo-first-order and pseudo-second-order kinetic and intraparticle diffusion model were used to evaluate the adsorption kinetic data. The kinetic data of two dyes could be better described by the pseudo second-order model. Thermodynamic data of the adsorption process were also obtained. It was found that the adsorption process of the two dyes were spontaneous and exothermic. PMID:24973701

Peng, Xiaoming; Huang, Dengpo; Odoom-Wubah, Tareque; Fu, Dafang; Huang, Jiale; Qin, Qingdong

2014-09-15

159

Mesoporous carbon originated from non-permanent porous MOFs for gas storage and CO2/CH4 separation.  

PubMed

Four nanoporous carbons prepared by direct carbonization of non-permanent highly porous MOF [Zn3(BTC)2 · (H2O)3]n without any additional carbon precursors. The carbonization temperature plays an important role in the pore structures of the resultant carbons. The Brunauer-Emmett-Teller (BET) surface areas of four carbon materials vary from 464 to 1671 m(2) g(-1) for different carbonization temperature. All the four carbon materials showed a mesoporous structure centered at ca. 3 nm, high surface area and good physicochemical stability. Hydrogen, methane and carbon dioxide sorption measurements indicated that the C1000 has good gas uptake capabilities. The excess H2 uptake at 77 K and 17.9 bar can reach 32.9 mg g(-1) and the total uptake is high to 45 mg g(-1). Meanwhile, at 95 bar, the total CH4 uptake can reach as high as 208 mg g(-1). Moreover the ideal adsorbed solution theory (IAST) prediction exhibited exceptionally high adsorption selectivity for CO2/CH4 in an equimolar mixture at 298 K and 1 bar (S(ads) = 27) which is significantly higher than that of some porous materials in the similar condition. PMID:25026895

Wang, Wenjing; Yuan, Daqiang

2014-01-01

160

Robust conductive mesoporous carbon?silica composite films with highly ordered and oriented orthorhombic structures from triblock-copolymer template co-assembly  

SciTech Connect

In this work, we describe a facile approach to improve the robustness of conductive mesoporous carbon-based thin films by the addition of silica to the matrix through the triconstituent organic-inorganic-organic co-assembly of resol (carbon precursor) and tetraethylorthosilicate (silica precursor) with triblock-copolymer Pluronic F127. The pyrolysis of the resol-silica-pluronic F127 film yields a porous composite thin film with well-defined mesostructure. X-Ray diffraction (XRD), grazing incidence small angle X-ray scattering (GISAXS), and electron microscopy measurements indicate that the obtained carbon-based thin films have a highly ordered orthorhombic mesostructure (Fmmm) with uniform large pore size ({approx}3 nm). The orthorhombic mesostructure is oriented and the (010) plane is parallel to the silicon wafer substrate. The addition of silica to the matrix impacts the pore size, surface area, porosity, modulus and conductivity. For composite films with approximately 40 wt% silica, the conductivity is decreased by approximately an order of magnitude in comparison to a pure carbon mesoporous film, but the conductivity is comparable to typical printed carbon inks used in electrochemical sensing, {approx}10 S cm{sup -1}. The mechanical properties of these mesoporous silica-carbon hybrid films are similar to the pure carbon analogs with a Young's modulus between 10 GPa and 15 GPa, but the material is significantly more porous. Moreover, the addition of silica to the matrix appears to improve the adhesion of the mesoporous film to a silicon wafer. These mesoporous silica-carbon composite films have appropriate characteristics for use in sensing applications.

Song, Lingyan; Feng, Dan; Campbell, Casey G.; Gu, Dong; Forster, Aaron M.; Yager, Kevin G.; Fredin, Nathaniel; Lee, Hae-Jeong; Jones, Ronald L.; Zhao, Dongyuan; Vogt, Bryan D. (AZU)

2012-07-11

161

Nanocasting of carbon films with interdigitated bimodal three-dimensionally ordered mesopores by template-replica coassembly.  

PubMed

Carbon films with interdigitated bimodal three-dimensionally ordered mesoporosity (ib3DOm) are realized by a scalable nanoreplication process that removes the common need plaguing hard-templating strategies for multistep prefabrication of porous sacrificial templates. Specifically, evaporation-induced convective codeposition of size-tunable (ca. 20-50 nm) silica nanoparticles with a surrogate molecular carbon precursor (glucose), followed by carbonization and template etching, leads to remarkably ordered, crack-free mesoporous carbon films of tunable thickness (ca. 100-1000 nm) and pore size. Association of the molecular carbon precursor with the assembling pore forming particles is found to transition the system among three distinct film morphologies (collapsed, ib3DOm C, disordered), thereby establishing a pseudophase behavior controlled by silica solids content and incipient glucose concentration. Namely, a parametric window wherein ib3DOm C films can be realized is identified, with a diffuse lower phase boundary associated with collapsing carbon films, and a more distinct order-to-disorder transition encountered at higher glucose concentrations. Mechanistic insight suggests that glucose association with the lysine-silica nanoparticle surface modulates the lattice spacing, d, of the periodically ordered mesopores in the coassembled films, with the onset of the order-to-disorder transition occurring at a critical normalized lattice spacing, dc/D ? 1.16. This appears to apply across the phase space associated with D = 50 nm silica particles and to translate among other phase spaces associated with smaller particles (e.g., 30 nm). We briefly demonstrate the robustness of the codeposition process for realizing ib3DOm C films on rough FTO glass substrates and show that, in this form, these materials hold potential as low-cost alternatives to costly platinum electrodes for dye-sensitized solar cells. PMID:25248486

Tian, Zheng; Snyder, Mark A

2014-10-21

162

Amperometric catechol biosensor based on laccase immobilized on nitrogen-doped ordered mesoporous carbon (N-OMC)/PVA matrix  

NASA Astrophysics Data System (ADS)

A functionalized nitrogen-containing ordered mesoporous carbon (N-OMC), which shows good electrical properties, was synthesized by the carbonization of polyaniline inside a SBA-15 mesoporous silica template. Based on this, through entrapping laccase onto the N-OMC/polyvinyl alcohol (PVA) film a facilely fabricated amperometric biosensor was developed. Laccase from Trametes versicolor was assembled on a composite film of a N-OMC/PVA modified Au electrode and the electrochemical behavior was investigated. The results indicated that the N-OMC modified electrode exhibits electrical properties towards catechol. The optimum experimental conditions of a biosensor for the detection of catechol were studied in detail. Under the optimal conditions, the sensitivity of the biosensor was 0.29 A*M-1 with a detection limit of 0.31 ?M and a linear detection range from 0.39 ?M to 8.98 ?M for catechol. The calibration curve followed the Michaelis-Menten kinetics and the apparent Michaelis-Menten \\left( K_{M}^{app} \\right) was 6.28 ?M. This work demonstrated that the N-OMC/PVA composite provides a suitable support for laccase immobilization and the construction of a biosensor.

Guo, Meiqing; Wang, Hefeng; Huang, Di; Han, Zhijun; Li, Qiang; Wang, Xiaojun; Chen, Jing

2014-06-01

163

In Situ intercalating expandable graphite for mesoporous carbon/graphite nanosheet composites as high-performance supercapacitor electrodes.  

PubMed

Mesoporous-carbon-coated graphite nanosheet (GNS@MC) composites have been synthesized by the intercalation of resol prepolymer into the interlayers of expandable graphite (EG) under vacuum-assisted conditions, followed by the exfoliation of EG through in situ polymerization, the growth of resol under hydrothermal conditions, and carbonization under Ar. The GNS@MC composites exhibit enhanced capacitive performance compared to mesoporous carbon (MC), microwaved EG after thermal treatment (T-EG), and the physical mixture of MC and T-EG (MC+T-EG). In particular, the GNS@MC-35-800 composite carbonized at 800 °C, which has a graphite-nanosheet content of 35 % and a Brunauer-Emmett-Teller surface area (S(BET) ) of 432.3 m(2) ?g(-1) , exhibits the highest capacitance of 203 F g(-1) at 1 A g(-1) in 6 M KOH electrolyte. Furthermore, the GNS@MC-35-800 composite exhibits a good cyclic stability with 95 % capacitance retention and a high columbic efficiency of 99 % after 5000 cycles. The energy density of the symmetric supercapacitor GNS@MC-35-800/GNS@MC-35-800 achieved was as high as 11.5 Wh kg(-1) at a high power density of 10 kW kg(-1) . This good performance is attributable to the GNSs in the GNS@MC composite facilitating electron transport owing to its excellent conductivity; moreover, the MC in GNS@MC favors the rapid diffusion of ions by providing low-resistance pathways. The GNS@MC composite may find application in high-performance energy storage and conversion devices. PMID:23081877

Wang, Lei; Mu, Guang; Tian, Chungui; Sun, Li; Zhou, Wei; Tan, Taixing; Fu, Honggang

2012-12-01

164

Influences of urea–glycerol mixtures as mixed mesopore-controlling agents on tailoring physicochemical properties and photocatalytic H{sub 2} production activity of sol–gel-derived mesoporous-assembled TiO{sub 2} nanocrystals  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Mesoporous-assembled TiO{sub 2} nanocrystals were synthesized by modified sol–gel process. ? Urea–glycerol mixtures were applied as mixed mesopore-controlling agents. ? Urea and glycerol contents affected physicochemical properties of synthesized TiO{sub 2}. ? Photocatalytic H{sub 2} production activity also depended on urea and glycerol contents. ? 75 mol% urea and 25 mol% glycerol yielded the most photocatalytically active TiO{sub 2}. -- Abstract: In this work, the mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts were successfully synthesized by a sol–gel process with the aid of urea–glycerol mixtures used as mixed mesopore-controlling agents. The photocatalytic activity of the synthesized mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts was investigated for hydrogen production from the water splitting reaction using methanol as a hole scavenger under UV light irradiation. The synthesized TiO{sub 2} nanocrystal photocatalysts were systematically characterized by TG–DTA, N{sub 2} adsorption–desorption, SEM, high resolution TEM, and XRD analyses. The characterization results showed that the well-controlled contents of urea and glycerol in a urea–glycerol mixture at 75 mol% urea and 25 mol% glycerol resulted in not only the most highly porous network (i.e. the highest specific surface area and total pore volume, and the smallest mean mesopore diameter), but also the smallest crystallite size of the synthesized TiO{sub 2} nanocrystal photocatalyst. The photocatalytic reaction results, hence, revealed a much superior photocatalytic hydrogen production activity of the mesoporous-assembled TiO{sub 2} nanocrystal synthesized with 75 mol% urea and 25 mol% glycerol to the other synthesized TiO{sub 2} nanocrystals, also being much higher than those of the commercially available P-25 TiO{sub 2} and ST-01 TiO{sub 2} powders.

Sreethawong, Thammanoon, E-mail: sreethawongt@imre.a-star.edu.sg [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore)] [Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A-STAR), 3 Research Link, Singapore 117602 (Singapore); Ngamsinlapasathian, Supachai, E-mail: wonone@hotmail.com [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)] [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Yoshikawa, Susumu [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)] [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)

2013-01-15

165

Bottom-up catalytic approach towards nitrogen-enriched mesoporous carbons/sulfur composites for superior Li-S cathodes.  

PubMed

We demonstrate a sustainable and efficient approach to produce high performance sulfur/carbon composite cathodes via a bottom-up catalytic approach. The selective oxidation of H2S by a nitrogen-enriched mesoporous carbon catalyst can produce elemental sulfur as a by-product which in-situ deposit onto the carbon framework. Due to the metal-free catalytic characteristic and high catalytic selectivity, the resulting sulfur/carbon composites have almost no impurities that thus can be used as cathode materials with compromising battery performance. The layer-by-layer sulfur deposition allows atomic sulfur binding strongly with carbon framework, providing efficient immobilization of sulfur. The nitrogen atoms doped on the carbon framework can increase the surface interactions with polysulfides, leading to the improvement in the trapping of polysulfides. Thus, the composites exhibit a reversible capacity of 939 mAh g(-1) after 100 cycles at 0.2 C and an excellent rate capability of 527 mAh g(-1) at 5 C after 70 cycles. PMID:24084754

Sun, Fugen; Wang, Jitong; Chen, Huichao; Qiao, Wenming; Ling, Licheng; Long, Donghui

2013-01-01

166

Bottom-Up Catalytic Approach towards Nitrogen-Enriched Mesoporous Carbons/Sulfur Composites for Superior Li-S Cathodes  

PubMed Central

We demonstrate a sustainable and efficient approach to produce high performance sulfur/carbon composite cathodes via a bottom-up catalytic approach. The selective oxidation of H2S by a nitrogen-enriched mesoporous carbon catalyst can produce elemental sulfur as a by-product which in-situ deposit onto the carbon framework. Due to the metal-free catalytic characteristic and high catalytic selectivity, the resulting sulfur/carbon composites have almost no impurities that thus can be used as cathode materials with compromising battery performance. The layer-by-layer sulfur deposition allows atomic sulfur binding strongly with carbon framework, providing efficient immobilization of sulfur. The nitrogen atoms doped on the carbon framework can increase the surface interactions with polysulfides, leading to the improvement in the trapping of polysulfides. Thus, the composites exhibit a reversible capacity of 939?mAh g?1 after 100 cycles at 0.2?C and an excellent rate capability of 527?mAh g?1 at 5?C after 70 cycles. PMID:24084754

Sun, Fugen; Wang, Jitong; Chen, Huichao; Qiao, Wenming; Ling, Licheng; Long, Donghui

2013-01-01

167

Study on the effect of different acids on the structure and photocatalytic activity of mesoporous titania  

NASA Astrophysics Data System (ADS)

Nanocrystalline mesoporous titania was synthesized via a combined sol-gel process with surfactant-assisted templating method using cetyltrimethyl ammonium bromide (CTAB) as the structure-directing agent. The process was catalyzed by different acid (hydrochloric acid, nitric acid, sulfuric acid, or phosphoric acid). The prepared samples were characterized by XRD, TEM, BET and FT-IR. The photocatalytic activity of the samples was determined by degradation of phenol in aqueous solution. Results showed that different acid had different effect on the structure and crystal phase of the samples. The sample adjusted by phosphoric acid showed highest surface area and photocatalytic activity. The formation mechanism of the samples catalyzed by different acid was also discussed.

Ao, Yanhui; Xu, Jingjing; Fu, Degang

2009-10-01

168

Water vapor adsorption onto activated carbons prepared from cattle manure compost (CMC)  

NASA Astrophysics Data System (ADS)

Activated carbons were prepared from cattle manure compost (CMC) using zinc chloride activation. The structural and surface chemical characteristics of CMC-based activated carbons were determined by N 2 adsorption-desorption and Boehm titration, respectively. The water vapor adsorption properties of the prepared activated carbons with various pore structure and surface nature were examined, and the mechanism of water adsorbed onto activated carbon was also discussed. The results show that the adsorption of water vapor on carbons begins at specific active sites at low relative humidity (RH), followed by micropore filling at medium RH through the formation of pentamer cluster of water molecules in the narrow micropores. The water vapor adsorption capacity of activated carbon is predominantly dependent on its pore volume and surface area. Although capillary condensation is not the mechanism for water adsorption onto activated carbon, water can adsorb on narrow mesopore to some extent.

Qian, Qingrong; Sunohara, Satoshi; Kato, Yuichi; Zaini, Muhammad Abbas Ahmad; Machida, Motoi; Tatsumoto, Hideki

2008-05-01

169

Granular activated carbon installations  

Microsoft Academic Search

This article presents a compilation and summary of design criteria, performance, and cost data from 22 operating municipal and industrial granular activated carbon (GAC) installations that treat water and wastewater or process food and beverage products. Guidance for using this information to estimate costs for GAC treatment of water supplies is provided. In conjunction with previous reports, this article may

Russell L. Culp; Robert M. Clark

1983-01-01

170

GRANULAR ACTIVATED CARBON INSTALLATIONS  

EPA Science Inventory

This paper presents a compilation and summary of design criteria, performance, and cost data from 22 operating municipal and industrial granular activated carbon (GAC) installations that treat water and wastewater or process food and beverage products. Guidance for using this inf...

171

Amino-functionalized mesoporous silica modified glassy carbon electrode for ultra-trace copper(II) determination.  

PubMed

This paper described a facile and direct electrochemical method for the determination of ultra-trace Cu(2+) by employing amino-functionalized mesoporous silica (NH2-MCM-41) as enhanced sensing platform. NH2-MCM-41 was prepared by using a post-grafting process and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fourier transform infrared (FTIR) spectroscopy. NH2-MCM-41 modified glassy carbon (GC) electrode showed higher sensitivity for anodic stripping voltammetric (ASV) detection of Cu(2+) than that of MCM-41 modified one. The high sensitivity was attributed to synergistic effect between MCM-41 and amino-group, in which the high surface area and special mesoporous morphology of MCM-41 can cause strong physical absorption, and amino-groups are able to chelate copper ions. Some important parameters influencing the sensor response were optimized. Under optimum experimental conditions the sensor linearly responded to Cu(2+) concentration in the range from 5 to 1000ngL(-1) with a detection limit of 0.9ngL(-1) (S/N=3). Moreover, the sensor possessed good stability and electrode renewability. In the end, the proposed sensor was applied for determining Cu(2+) in real samples and the accuracy of the results were comparable to those obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) method. PMID:25263113

Dai, Xingxin; Qiu, Fagui; Zhou, Xuan; Long, Yumei; Li, Weifeng; Tu, Yifeng

2014-10-27

172

Synthesis of Co-containing mesoporous carbon foams using a new cobalt-oxo cluster as a precursor  

SciTech Connect

A novel trinuclear cobalt-oxo cluster 2[Co{sub 3}O(Ac){sub 6}(H{sub 2}O){sub 3}]{center_dot}H{sub 2}O (Co-OXO) has been obtained and characterized by X-ray single-crystal diffraction and elemental analysis. The structure of Co-OXO displays 3D supramolecular networks through hydrogen bonds and generates boron nitride (bnn) topology. Co-OXO was further used as a precursor to synthesize Co-containing mesoporous carbon foams (Co-MCFs), which exhibit highly ordered mesostructure with specific surface area of 614 m{sup 2} g{sup -1} and uniform pore size of 2.7 nm. Charge-discharge tests show that the specific discharge capacitance of Co-MCFs is 7% higher than that of the MCFs at the current density of 100 mA g{sup -1}, and 26% higher than that of MCFs at the current density of 3 A g{sup -1}. The electrochemical behaviors of Co-MCFs are obviously improved due to the improved wettability, increased graphitization degree and the pseudo-capacitance through additional faradic reactions arising from cobalt. - Graphical Abstract: A new trinuclear cobalt-oxo cluster, 2[Co{sub 3}O(Ac){sub 6}(H{sub 2}O){sub 3}]{center_dot}H{sub 2}O (1), was obtained and further used as a precursor to synthesize Co-containing mesoporous carbon foams (Co-MCFs) which exhibit improved electrochemical behaviors. Highlights: Black-Right-Pointing-Pointer A new trinuclear cobalt-oxo cluster (1) were obtained. Black-Right-Pointing-Pointer 1 is joined by hydrogen bonds to construct a 3D structure showing bnn topology. Black-Right-Pointing-Pointer 1 was further used to obtain Co-containing mesoporous carbon foams (Co-MCFs). Black-Right-Pointing-Pointer Co-MCFs exhibit highly ordered mesostructure and uniform pore sizes. Black-Right-Pointing-Pointer Electrochemical behaviors of Co-MCFs are obviously improved compared with pure MCFs.

Lv Yaokang [Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Feng Yunlong [Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua, Zhejiang 321004 (China); Gan Lihua, E-mail: ganlh@tongji.edu.cn [Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092 (China); Liu Mingxian; Xu Liang; Liu Cao; Zheng Haowen; Li Jie [Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai 200092 (China)

2012-01-15

173

Activated carbons modified with aluminium–zirconium polycations as adsorbents for ammonia  

Microsoft Academic Search

Microporous\\/mesoporous wood-based activated carbon was modified by impregnation with aluminium–zirconium oxycations and calcined at 300°C, and then used as an adsorbent of ammonia. Water was present either on the carbon or in the gas phase. The initial (before ammonia adsorption) and exhausted materials were characterized using adsorption of nitrogen, potentiometric titration, XRD, FTIR and thermal analysis. Aluminium–zirconium polycations improve ammonia

Camille Petit; Teresa J. Bandosz

2008-01-01

174

In-Situ Observation of Solid Electrolyte Interphase Formation in Ordered Mesoporous Hard Carbon by Small-Angle Neutron Scattering  

SciTech Connect

The aim of this work was to better understand the electrochemical processes occurring during the cycling of a lithium-ion half-cell containing ordered mesoporous hard carbon using time-resolved in situ small-angle neutron scattering (SANS). Utilizing electrolytes containing mixtures of deuterated (2H) and non-deuterated (1H) carbonates, we have addressed the challenging task of monitoring the formation and evolution of the solid-electrolyte interphase (SEI) layer. An evolution occurs in the SEI layer during discharge from a composition dominated by a higher scattering length density (SLD) lithium salt, to a lower SLD lithium salt for the ethylene carbonate/dimethyl carbonate (EC/DMC) mixture employed. By comparing half-cells containing different solvent deuteration levels, we show that it is possible to observe both SEI formation and lithium intercalation occurring concurrently at the low voltage region in which lithium intercalates into the hard carbon. These results demonstrate that SANS can be employed to monitor complicated electrochemical processes occurring in rechargeable batteries, in a manner that simultaneously provides information on the composition and microstructure of the electrode.

Bridges, Craig A [ORNL; Paranthaman, Mariappan Parans [ORNL; Sun, Xiao-Guang [ORNL; Zhao, Jinkui [ORNL; Dai, Sheng [ORNL

2012-01-01

175

Properties of pyrolytic chars and activated carbons derived from pilot-scale pyrolysis of used tires.  

PubMed

Used tires were pyrolyzed in a pilot-scale quasi-inert rotary kiln. Influences of variables, such as time, temperature, and agent flow, on the activation of obtained char were subsequently investigated in a laboratory-scale fixed bed. Mesoporous pores are found to be dominant in the pore structures of raw char. Brunauer-Emmett-Teller (BET) surfaces of activated chars increased linearly with carbon burnoff. The carbon burnoff of tire char achieved by carbon dioxide (CO2) under otherwise identical conditions was on average 75% of that achieved by steam, but their BET surfaces are almost the same. The proper activation greatly improved the aqueous adsorption of raw char, especially for small molecular adsorbates, for example, phenol from 6 to 51 mg/g. With increasing burnoff, phenol adsorption exhibited a first-stage linear increase followed by a rapid drop after 30% burnoff. Similarly, iodine adsorption first increased linearly, but it held as the burnoff exceeded 40%, which implied that the reduction of iodine adsorption due to decreasing micropores was partially made up by increasing mesopores. Both raw chars and activated chars showed appreciable adsorption capacity of methylene-blue comparable with that of commercial carbons. Thus, tire-derived activated carbons can be used as an excellent mesoporous adsorbent for larger molecular species. PMID:16259427

Li, S Q; Yao, Q; Wen, S E; Chi, Y; Yan, J H

2005-09-01

176

Effects of pyrolysis conditions on the porous structure construction of mesoporous charred carbon from used cigarette filters  

NASA Astrophysics Data System (ADS)

One-step pyrolysis was applied to synthesize mesoporous charred carbon from used cigarette filters. Proximate analysis suggested that cigarette filters are decent carbon precursors due to their moderate carbon (around 11 %) and low ash (around 0.1 %) contents. To investigate the effects of pyrolysis parameters on porous surface area, a full factorial design of experiment including heating rate, soaking time and pyrolysis temperature was used with each factor at three levels. The analysis of variance revealed that the temperature and heating rate had the most significant effects on total surface area of the synthesized carbon. Response surface model (RSM) was applied to best fit a surface through the experimental data. It was seen that the quadratic RSM model with a reasonable R 2 value of 63 % was the best developed model. The maximum BET surface area (597 m2/g) was reached at a pyrolysis temperature of 900 °C when the precursor was heated at 5 °C/min and hold at this temperature for 3 h. The produced N2 adsorption-desorption isotherm showed a certain degree of mesoporosity in the charred carbon with an average pore size of 3.32 nm calculated by Barrett-Joyner-Halenda method. Scanning electron microscopy also showed the presence of macroporosity on the charred carbon surface. Fourier transform infrared spectroscopy revealed the presence of acidic surface functional groups such as carboxyl and phenol which were accordingly confirmed by Boehm titration. In addition, Boehm titration showed that the produced carbon's surface was more acidic than basic in nature.

Masoudi Soltani, Salman; Yazdi, Sara Kazemi; Hosseini, Soraya

2013-05-01

177

Study on the synthesis of Ni doped mesoporous TiO 2 and its photocatalytic activity for hydrogen evolution in aqueous methanol solution  

Microsoft Academic Search

Ni doped mesoporous TiO2 photocatalyst was prepared. XRD and EDX results indicated that Ni2+ was incorporated into the framework of the mesoporous TiO2 in a highly dispersed way. The results of photocatalytic hydrogen evolution in aqueous methanol solution under UV–Vis light irradiation showed that activity of hydrogen production strongly depended on the amount of Ni doped. The highest activity was

Dengwei Jing; Yaojun Zhang; Liejin Guo

2005-01-01

178

Properties of Pyrolytic Chars and Activated Carbons Derived from Pilot-Scale Pyrolysis of Used Tires  

Microsoft Academic Search

Used tires were pyrolyzed in a pilot-scale quasi-inert rotary kiln. Influences of variables, such as time, temperature, and agent flow, on the activation of obtained char were subsequently investigated in a laboratory-scale fixed bed. Meso-porous pores are found to be dominant in the pore structures of raw char. Brunauer-Emmett-Teller (BET) surfaces of activated chars increased linearly with carbon burnoff. The

S.-Q. Li; Q. Yao; S.-E. Wen; Y. Chi; J.-H. Yan

2005-01-01

179

Visible-light photocatalytic activity of gold nanoparticles supported on template-synthesized mesoporous titania for the decontamination of the chemical warfare agent Soman  

Microsoft Academic Search

Mesoporous titania containing gold nanoparticles has been found to be an efficient photocatalyst for the visible-light decontamination of Soman. This contrasts with the complete lack of visible-light activity of analogous mesoporous titania sample without containing Au and is attributed to light absorption by the gold nanoparticles surface plasmon band. The possibility that Soman degradation occurs by light-induced heating is unlikely

Mercedes Alvaro; Bogdan Cojocaru; Adel A. Ismail; Nicoleta Petrea; Belen Ferrer; Farid A. Harraz; Vasile I. Parvulescu; Hermenegildo Garcia

2010-01-01

180

Synthesis, characterization, and photocatalytic activity for hydrogen evolution of nanocrystalline mesoporous titania prepared by surfactant-assisted templating sol–gel process  

Microsoft Academic Search

Nanocrystalline mesoporous titania was synthesized via a combined sol–gel process with surfactant-assisted templating method, treated under various calcination conditions, and evaluated for its photocatalytic activity through photocatalytic hydrogen evolution from an aqueous methanol solution. In this synthetic method, applied surfactant template molecules functioned as both mesopore-forming and gelation-assisting agents. The resulting products were methodically characterized by TG-DTA, XRD, N2 adsorption–desorption,

Thammanoon Sreethawong; Yoshikazu Suzuki; Susumu. Yoshikawa

2005-01-01

181

Voltammetric detection of lead (II) and mercury (II) using a carbon paste electrode modified with thiol self-assembled monolayer on mesoporous silica (SAMMS)  

Microsoft Academic Search

The anodic stripping voltammetry at a carbon paste electrode modified with thiol terminated self-assembled monolayer on mesoporous silica (SH-SAMMS) provides a new sensor for simultaneous detection of lead (Pb2+) and mercury (Hg2+) in aqueous solutions. The overall analysis involved a two-step procedure: an accumulation step at open circuit, followed by medium exchange to a pure electrolyte solution for the stripping

Wassana Yantasee; Yuehe Lin; Thomas S. Zemanian; Glen E. Fryxell

2003-01-01

182

Simultaneous detection of cadmium, copper, and lead using a carbon paste electrode modified with carbamoylphosphonic acid self-assembled monolayer on mesoporous silica (SAMMS)  

Microsoft Academic Search

A new sensor was developed for simultaneous detection of cadmium (Cd2+), copper (Cu2+), and lead (Pb2+), based on the voltammetric response at a carbon paste electrode modified with carbamoylphosphonic acid (acetamide phosphonic acid) self-assembled monolayer (SAM) on mesoporous silica (Ac-Phos SAMMS). The adsorptive stripping voltammetry (AdSV) technique involves preconcentration of the metal ions onto Ac-Phos SAMMS under an open circuit,

Wassana Yantasee; Yuehe Lin; Glen E. Fryxell; Brad J. Busche

2004-01-01

183

Direct electrochemistry and electrocatalysis of glucose oxidase immobilized on glassy carbon electrode modified by Nafion and ordered mesoporous silica-SBA-15  

Microsoft Academic Search

In this paper, it was found that glucose oxidase (GOD) has been stably immobilized on glassy carbon electrode modified by ordered mesoporous silica-SBA-15 and Nafion. The sorption behavior of GOD immobilized on SBA-15 matrix was characterized by transmission electron microscopy (TEM), ultraviolet–visible (UV–vis), FTIR, respectively, which demonstrated that SBA-15 can facilitate the electron exchange between the electroactive center of GOD

Kunqi Wang; Hua Yang; Lin Zhu; Jianhui Liao; Tianhong Lu; Wei Xing; Shenyang Xing; Qiang Lv

2009-01-01

184

Fabrication of polyamide thin-film nano-composite (PA-TFN) membrane with hydrophilized ordered mesoporous carbon (H-OMC) for water purifications  

Microsoft Academic Search

To enhance the performance of thin-film composite (TFC) membranes, nano-fillers are often used as additives in the polymerization process. Nano-fillers have to be hydrophilic to be dispersed in the aqueous phase to make thin-film nano-composite membrane (TFN) by interfacial polymerization. In this study, hydrophilized ordered mesoporous carbons (H-OMCs) were explored for TFN preparation. H-OMC was prepared from silica template, and

Eun-Sik Kim; Baolin Deng

2011-01-01

185

Dewatering Peat With Activated Carbon  

NASA Technical Reports Server (NTRS)

Proposed process produces enough gas and carbon to sustain itself. In proposed process peat slurry is dewatered to approximately 40 percent moisture content by mixing slurry with activated carbon and filtering with solid/liquid separation techniques.

Rohatgi, N. K.

1984-01-01

186

Polymer composite electrolytes containing ionically active mesoporous SiO2 particles  

NASA Astrophysics Data System (ADS)

In exploring approaches to enhance ionic conductivity of solid polymer electrolytes, adding inert fillers has proved to be effective. In the present work, by doping ionically active SiO2 particles, which were designed by absorbing and confining liquid plasticizers in the nanosized pores of SBA-15 (a kind of mesoporous SiO2) to the polyethylene oxide (PEO)-LiClO4 matrix, about 10-fold further enhancement in the ionic conductivity was achieved as compared with adding inert SBA-15. The fillers dispersed homogenously in the PEO matrix. The ambient ionic conductivity reaches about 1.5×10-4 S cm-1 for (PEO)8-LiClO4/10 wt % active SBA-15 films. Moreover, other properties such as the ambient lithium transference number, long-term stability of bulk and lithium metal electrode/electrolyte interfacial resistance, and the electrochemical window also showed good results. Application of such electrolytes in lithium batteries was asserted by cell testing with LiCoO2 cathode and lithium metal anode.

Wang, Xiao-Liang; Mei, Ao; Li, Ming; Lin, Yuan-Hua; Nan, Ce-Wen

2007-09-01

187

Improving adsorption and activation of the lipase immobilized in amino-functionalized ordered mesoporous SBA-15  

NASA Astrophysics Data System (ADS)

Ordered mesoporous SBA-15 was prepared by hydrothermal process and was functionalized with(3-aminopropyl) triethoxysilane (APTES) by post-synthesis-grafting method. The materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectrometer (EDS), small-angle X-ray powder diffraction (SAXRD), N 2 adsorption-desorption and Fourier transform infrared spectroscopy (FT-IR). The results indicated that SBA-15 had a 2-dimensional hexagonal p6 mm mesoscopic structure and the mesoscopic structure was remained after the functionalization procedure. The activities of porcine pancreatic lipase (PPL) immobilized in SBA-15 by physical adsorption and in APTES functionalized SBA-15 by chemical adsorption were studied by hydrolysis of triacetin. Chemically adsorbed PPL showed higher loading amount and catalytic activity comparing with physically adsorbed PPL. The stability of immobilized PPL against thermal and pH of reaction medium was significantly improved. Recycling experiments showed that chemically adsorbed PPL exhibited better reusability than physically adsorbed PPL.

Xu, Yun-qiang; Zhou, Guo-wei; Wu, Cui-cui; Li, Tian-duo; Song, Hong-bin

2011-05-01

188

Activated carbon from vetiver roots: gas and liquid adsorption studies.  

PubMed

Large quantities of lignocellulosic residues result from the industrial production of essential oil from vetiver grass (Vetiveria zizanioides) roots. These residues could be used for the production of activated carbon. The yield of char obtained after vetiver roots pyrolysis follows an equation recently developed [A. Ouensanga, L. Largitte, M.A. Arsene, The dependence of char yield on the amounts of components in precursors for pyrolysed tropical fruit stones and seeds, Micropor. Mesopor. Mater. 59 (2003) 85-91]. The N(2) adsorption isotherm follows either the Freundlich law K(F)P(alpha) which is the small alpha equation limit of a Weibull shaped isotherm or the classical BET isotherm. The surface area of the activated carbons are determined using the BET method. The K(F) value is proportional to the BET surface area. The alpha value increases slightly when the burn-off increases and also when there is a clear increase in the micropore distribution width. PMID:17092643

Gaspard, S; Altenor, S; Dawson, E A; Barnes, P A; Ouensanga, A

2007-06-01

189

Simple fabrication of N-doped mesoporous TiO2 nanorods with the enhanced visible light photocatalytic activity  

PubMed Central

N-doped mesoporous TiO2 nanorods were fabricated by a modified and facile sol–gel approach without any templates. Ammonium nitrate was used as a raw source of N dopants, which could produce a lot of gasses such as N2, NO2, and H2O in the process of heating samples. These gasses were proved to be vitally important to form the special mesoporous structure. The samples were characterized by the powder X-ray diffraction, X-ray photoelectron spectrometer, nitrogen adsorption isotherms, scanning electron microscopy, transmission electron microscopy, and UV-visible absorption spectra. The average length and the cross section diameter of the as-prepared samples were ca. 1.5 ?m and ca. 80 nm, respectively. The photocatalytic activity was evaluated by photodegradation of methylene blue (MB) in aqueous solution. The N-doped mesoporous TiO2 nanorods showed an excellent photocatalytic activity, which may be attributed to the enlarged surface area (106.4 m2 g-1) and the narrowed band gap (2.05 eV). Besides, the rod-like photocatalyst was found to be easy to recycle. PMID:24428848

2014-01-01

190

Electrochemical determination of toxic ractopamine at an ordered mesoporous carbon modified electrode.  

PubMed

A sensitive electrochemical sensor was developed to detect toxic ractopamine using ordered mesoporus carbon (OMC) modified glass carbon electrode (OMC/GCE). Cyclic voltammetry was used to investigate the electrochemical behaviours of ractopamine on OMC/GCE. The results indicated that the OMC modified electrode can remarkably enhance electrocatalytic activity towards the oxidation of ractopamine with a great increase of peak current. The oxidation mechanism was studied and the results showed that the oxidation of ractopamine involved two protons and two electrons of its two phenolic hydroxyl groups. The signal for the determination of ractopamine was recorded using differential pulse voltammetry (DPV) and the optimisation for the experimental conditions was also conducted. The results showed that the response of the sensor to concentration of ractopamine displayed a linear correlation over a range from 0.085 ?M to 8.0 ?M with a detection limit of 0.06 ?M, demonstrating favourable sensitivity and selectivity for the detection of ractopamine. Finally, the method was successfully applied for the determination of ractopamine in pork samples with satisfying recoveries in the range of 96.6-104.5% and excellent RSD of less than 5%. PMID:24128523

Yang, Xiao; Feng, Bo; Yang, Peng; Ding, Yonglan; Chen, Yi; Fei, Junjie

2014-02-15

191

Preparation of mesoporous Si-C-O fibers with a narrow mesopore size distribution.  

PubMed

Mesoporous Si-C-O fibers were fabricated by air activation of a kind of carbon-rich SiC-C fibers at 600 degrees C. The SiC-C fibers were prepared from the hybrid precursor of polycarbosilane and pitch through melt-spinning, air curing and pyrolysis in nitrogen. The carbon content of the SiC-C fibers was 54.4 wt%, and decreased to lower than 25 wt% after activation for more than 5 hours. Meanwhile, the surface area increased up to 260 m2/g, with a narrow mesopore size distribution mainly in the range of 2-5 nm. The SiC-phase derived from the polycarbosilane and the C-phase derived from the pitch form a bicontinuous interpenetrating network, which plays an important role for the narrow pore size distribution. PMID:23755678

Li, Chengyong; He, Rongan; Zhang, Shiying; Liu, Jingyu; Yang, Ning

2013-03-01

192

Activation of Snap-Top Capped Mesoporous Silica Nano Containers Using Two Near-Infrared Photons  

PubMed Central

Photoactivation of “snap-top” stoppers over the pore openings of mesoporous silica nanoparticles releases intact cargo molecules from the pores. The on-command release can be stimulated by either one UV photon or two coherent near-IR photons. Two-photon activation is particularly desirable for use in biological systems because it enables good tissue penetration and precise spatial control. Stoppers were assembled by first binding photolabile coumarin-based molecules to the nanoparticle surface. Then, after loading the particles with cargo, bulky ?-cyclodextrin molecules were noncovalently associated with the substituted coumarin molecule, blocking the pores and preventing the cargo from escaping. One-photon excitation at 376 nm or two-photon excitation at 800 nm cleaves the bond holding the coumarin to the nanopore, releasing both the cyclodextrin cap and the cargo. The dynamics of both the cleavage of the cap and the cargo release was monitored using fluorescence spectroscopy. This system traps intact cargo molecules without the necessity of chemical modification, releases them with tissue penetrating near-IR light and have possible applications in photo-stimulated drug delivery. PMID:24015927

Guardado-Alvarez, Tania M.; Devi, Lekshmi Sudha; Russell, Melissa M.; Schwartz, Benjamin J.

2013-01-01

193

Probing mechanisms for enzymatic activity enhancement of organophosphorus hydrolase in functionalized mesoporous silica  

PubMed Central

We have previously reported that organophosphorus hydrolase (OPH) can be spontaneously entrapped in functionalized mesoporous silica (FMS) with HOOC-as the functional groups and the entrapped OPH in HOOC-FMS showed enhanced enzyme specific activity. This work is to study the mechanisms that why OPH entrapped in FMS displayed the enhanced activity in views of OPH-FMS interactions using spectroscopic methods. The circular dichroism (CD) spectra show that, comparing to the secondary structure of OPH free in solution, OPH in HOOC-FMS displayed increased ?-helix/?-strand transition of OPH with increased OPH loading density. The fluorescence emission spectra of Trp residues were used to assess the tertiary structural changes of the enzyme. There was a 42% increase in fluorescence. This is in agreement with the fact that the fluorescence intensity of OPH was increased accompanying with the increased OPH activity when decreasing urea concentrations in solution. The steady-state anisotropy was increased after OPH entrapping in HOOC-FMS comparing to the free OPH in solution, indicating that protein mobility was reduced upon entrapment. The solvent accessibility of Trp residues of OPH was probed by using acrylamide as a collisional quencher. Trp residues of OPH-FMS had less solvent exposure comparing with free OPH in solution due to its electrostatical binding to HOOC-FMS thereby displaying the increased fluorescence intensity. These results suggest the interactions of OPH with HOOC-FMS resulted in the protein immobilization and a favorable conformational change for OPH in the crowded confinement space and accordingly the enhanced activity. PMID:19874798

Chen, Baowei; Lei, Chenghong; Shin, Yongsoon; Liu, Jun

2009-01-01

194

Highly ordered mesoporous carbon nanomatrix as a new approach to improve the oral absorption of the water-insoluble drug, simvastatin.  

PubMed

Three different kinds of highly ordered mesoporous carbon (HMC) matrices with different morphologies (hexagonal, spherical and fibrous), particle sizes (700 nm, 400-900 nm and 1-4 ?m) and pore diameters were compared as drug carriers for a model drug, simvastatin (SIM). The physicochemical properties of the SIM-loaded composites were studied using field emission scanning electron microscopy (FESEM), specific surface area analysis, differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS), HPLC, solubility measurement and dissolution testing. Furthermore, the oral bioavailability of SIM-loaded SHMC (spherical HMC nanomatrix) in beagle dogs was compared with that of the reference formulation (Zocor®). The results obtained showed that SIM molecules are encapsulated in a noncrystalline state due to geometric confinement in the nanopores of HMC. In vitro dissolution testing showed that the dissolution rate of SIM released from monodispersed SHMC was significantly faster compared with that of crystalline SIM and other SIM-loaded composites. In addition, in vivo bioavailability study demonstrated that the relative bioavailability of SIM and SIM ?-hydroxy acid (an active metabolite of SIM) for SIM-loaded SHMC formulation was 138.42% and 163.55%, respectively. In conclusion, monodispersed SHMC appear to be a more promising candidate as a new oral drug delivery vehicle providing a rapid drug release and enhanced oral bioavailability. PMID:23791638

Zhang, Yanzhuo; Wang, Huan; Gao, Cunqiang; Li, Xue; Li, Lusi

2013-08-16

195

Physicochemical and porosity characteristics of thermally regenerated activated carbon polluted with biological activated carbon process.  

PubMed

The characteristics of thermally regenerated activated carbon (AC) polluted with biological activated carbon (BAC) process were investigated. The results showed that the true micropore and sub-micropore volume, pH value, bulk density, and hardness of regenerated AC decreased compared to the virgin AC, but the total pore volume increased. XPS analysis displayed that the ash contents of Al, Si, and Ca in the regenerated AC respectively increased by 3.83%, 2.62% and 1.8%. FTIR spectrum showed that the surface functional groups of virgin and regenerated AC did not change significantly. Pore size distributions indicated that the AC regeneration process resulted in the decrease of micropore and macropore (D>10?m) volume and the increase of mesopore and macropore (0.1?m

Dong, Lihua; Liu, Wenjun; Jiang, Renfu; Wang, Zhansheng

2014-11-01

196

THERMOCHEMICAL STORAGE OF LOW TEMPERATURE HEAT BY ZEOLITES; SAPO'S AND IMPREGNATED ACTIVE CARBON  

Microsoft Academic Search

The adsorption behaviour and storage properties of common and new microporous materials such as low silica X zeolites (LSX), SAPO and with CaCl2 impregnated active carbon were investigated by means of TG\\/DSC, the measurements of adsorption isotherms and using a lab-scaled storages of 1.5 L volume. Tests of common zeolites and mesoporous materials (silica gel) in a lab-scaled storages showed

J. Jänchen; E. Weilerb Ackermannb; H. Stach

197

Liquid-phase adsorption: Characterization and use of activated carbon prepared from diosgenin production residue  

Microsoft Academic Search

The adsorption behavior of activated carbon (AC) prepared from the residue of diosgenin by-product was characterized. The adsorption capacities of AC such as iodine, phenol and methylene blue (MB) are 933.28, 145.38 and 165mg\\/g, respectively. The results of MP analysis and BJH method show AC has developed micropore and mesopore volumes, which are 0.1621 and 0.2623cm3\\/g respectively, with the mean

Caixiang Zhang; Yanxin Wang; Xifeng Yan

2006-01-01

198

Mesoporous carbon nitride based biosensor for highly sensitive and selective analysis of phenol and catechol in compost bioremediation.  

PubMed

Herein, we reported here a promising biosensor by taking advantage of the unique ordered mesoporous carbon nitride material (MCN) to convert the recognition information into a detectable signal with enzyme firstly, which could realize the sensitive, especially, selective detection of catechol and phenol in compost bioremediation samples. The mechanism including the MCN based on electrochemical, biosensor assembly, enzyme immobilization, and enzyme kinetics (elucidating the lower detection limit, different linear range and sensitivity) was discussed in detail. Under optimal conditions, GCE/MCN/Tyr biosensor was evaluated by chronoamperometry measurements and the reduction current of phenol and catechol was proportional to their concentration in the range of 5.00 × 10(-8)-9.50 × 10(-6)M and 5.00 × 10(-8)-1.25 × 10(-5)M with a correlation coefficient of 0.9991 and 0.9881, respectively. The detection limits of catechol and phenol were 10.24 nM and 15.00 nM (S/N=3), respectively. Besides, the data obtained from interference experiments indicated that the biosensor had good specificity. All the results showed that this material is suitable for load enzyme and applied to the biosensor due to the proposed biosensor exhibited improved analytical performances in terms of the detection limit and specificity, provided a powerful tool for rapid, sensitive, especially, selective monitoring of catechol and phenol simultaneously. Moreover, the obtained results may open the way to other MCN-enzyme applications in the environmental field. PMID:24951922

Zhou, Yaoyu; Tang, Lin; Zeng, Guangming; Chen, Jun; Cai, Ye; Zhang, Yi; Yang, Guide; Liu, Yuanyuan; Zhang, Chen; Tang, Wangwang

2014-11-15

199

Characterization of the micropore structure of activated carbons by adsorptions of nitrogen and some hydrocarbons  

SciTech Connect

In the present study the effects of the duration of carbonization and physical activation properties of activated carbon from vegetable materials were investigated. Peanut shells were used to obtain active carbon. These shells were activated chemically with ZnCl{sub 2} and/or CO{sub 2} for different times, and the micropore structures of these active carbons were studied by measuring the adsorption isotherms for nitrogen and some hydrocarbons such as benzene, n-butane, isobutane, 2,2-dimethylbutane, and isooctane. As the physical activation time was increased, the primary micropores, which were measured at 0.01 relative pressure, were reduced, and they were replaced by larger secondary and tertiary micropores which were measured at 0.15--0.01 and 0.30--0.15 relative pressures. The ratios of the mesopore volume to the micropore volume also increased as the duration of physical activation increased.

Guezel, F. [Dicle Univ., Diyarbakir (Turkey). Dept. of Chemistry] [Dicle Univ., Diyarbakir (Turkey). Dept. of Chemistry

1999-02-01

200

CO2-assisted synthesis of mesoporous carbon/C-doped ZnO composites for enhanced photocatalytic performance under visible light.  

PubMed

Visible-light-responsive mesoporous carbon/C-doped ZnO (mC/C-ZnO) composites were fabricated using a facile, fast, one-step process in CO2-expanded ethanol solution. It is a green and sustainable process that does not need tedious pretreatment, surfactants or precipitants. CO2 played triple roles in the synthesis of mC/C-ZnO composites; the first was to provide a simple physical expansion to evenly dope the carbon in the ZnO; the second was to offer some chemical groups such as CO3(2-) and HCO3(-), facilitating the uniform and complete deposition through the coordination of a metallic cation with these anions; and the third was to offer CO3(2-) acting as a template for the formation of mesoporosity in the carbon. When used as a photocatalyst for the photodegradation of RhB and the organic pollutant phenol, the mC/C-ZnO composites with glucose content at 22 wt% (mC/C-ZnO-CE-2) synthesized in CO2-expanded ethanol exhibited better recycling stability and photodegradation rate than the corresponding sample synthesized in pure ethanol. Such improved photocatalytic performance was attributed to the well-mixing of the mesoporous carbon and the small sized C-doped ZnO particles in the mC/C-ZnO-CE-2 composites. The facile and fast synthesis method could be extended to other mesoporous carbon/C-doped metal oxide composites, which are expected to be good photocatalyst candidates, or in other application fields. PMID:25249436

Wang, Fangxiao; Liang, Lin; Shi, Lei; Liu, Mengshuai; Sun, Jianmin

2014-10-14

201

Minimizing activated carbons production cost  

Microsoft Academic Search

A detailed economic evaluation of activated carbons production process from various raw materials is undertaken using the conventional economic indices (ROI, POT, and NPV). The fundamental factors that affect production cost were taken into account. It is concluded that for an attractive investment in activated carbons production one should select the raw material with the highest product yield, adopt a

G. G. Stavropoulos; A. A. Zabaniotou

2009-01-01

202

Preparation of activated carbons from macadamia nut shell and coconut shell by air activation  

SciTech Connect

A novel, three-step process for the production of high-quality activated carbons from macadamia nut shell and coconut shell charcoals is described. In this process the charcoal is (1) heated to a high temperature (carbonized), (2) oxidized in air following a stepwise heating program from low (ca. 450 K) to high (ca. 660 K) temperatures (oxygenated), and (3) heated again in an inert environment to a high temperature (activated). By use of this procedure, activated carbons with surface areas greater than 1,000 m{sub 2}/g are manufactured with an overall yield of 15% (based on the dry shell feed). Removal of carbon mass by the development of mesopores and macropores is largely responsible for increases in the surface area of the carbons above 600 m{sub 2}/g. Thus, the surface area per gram of activated carbon can be represented by an inverse function of the yield for burnoffs between 15 and 60%. These findings are supported by mass-transfer calculations and pore-size distribution measurements. A kinetic model for gasification of carbon by oxygen, which provides for an Eley-Rideal type reaction of a surface oxide with oxygen in air, fits the measured gasification rates reasonably well over the temperature range of 550--660 K.

Tam, M.S.; Antal, M.J. Jr.

1999-11-01

203

A novel carbon fiber based porous carbon monolith  

SciTech Connect

A novel porous carbon material based on carbon fibers has been developed. The material, when activated, develops a significant micro- or mesopore volume dependent upon the carbon fiber type utilized (isotropic pitch or polyacrylonitrile). The materials will find applications in the field of fluid separations or as a catalyst support. Here, the manufacture and characterization of our porous carbon monoliths are described.

Burchell, T.D.; Klett, J.W.; Weaver, C.E.

1995-07-01

204

Ultrahigh porosity in mesoporous MOFs: promises and limitations.  

PubMed

Mesoporous MOFs are currently record holders in terms of the specific surface area with values exceeding 7000 m(2) g(-1), a textural feature unattained by traditional porous solids such as zeolites, carbons and even by graphene. They are promising candidates for high pressure gas storage and also for conversion or separation of larger molecules, whose size exceeds the pore size of zeolites. The rational strategies for synthesis of mesoporous MOF are outlined and the unambiguous consistent assessment of the surface area of such ultrahighly porous materials, as well as present challenges in the exciting research field, of mesoporous MOFs are discussed. The crystallinity, dynamic properties, functional groups, and wide range tunability render these materials as exceptional solids, but for the implementation in functional devices and even in industrial processes several aspects and effective characteristics (such as volumetric storage capacities, recyclability, mechanical and chemical stability, activation) should be addressed. PMID:24722662

Senkovska, Irena; Kaskel, Stefan

2014-07-11

205

Sensitive immunosensor for the label-free determination of tumor marker based on carbon nanotubes/mesoporous silica and graphene modified electrode.  

PubMed

A novel label-free immunoassay strategy for sensitive detection of ?-fetoprotein (AFP) was proposed based on controlled fabrication of single-wall carbon nanotubes (CNTs) inside the channels of mesoporous silica (MPS). The silanol groups on the internal pore walls of MPS were grafted with amino groups, while the silanol groups on the external surface were blocked by trimethylchlorosilane (TMCS). Thus, CNTs and the monoclonal antibodies of AFP (anti-AFP) could be confined inside the mesopores of MPS by the covalent linking of the carboxyl and amino groups. For the preparation of immunosensing electrode, graphene sheets (GS) and anti-AFP/CNTs/TMCS-MPS were coated on the electrode surface based on layer by layer assembly. After dipping the anti-AFP/CNTs/TMCS-MPS/GS/GCE into the sample solution, the immunoconjugates formed after the immunological reaction, which resulted in the increment of spatial blocking and impedance of the immunosensing interface. Thus, the peak current decreased with the increasing concentration of AFP. CNTs inside the mesopores could promote the electron transportation through the pore channel. Meanwhile, modified GS with distinctive conduction capacity could also improve the electrochemical response. Under the optimal experimental conditions, the label-free immunosensor could detect AFP in a linear range from 0.1 to 100 ng mL(-1) with a detection limit of 0.06 ng mL(-1) (3?). PMID:23010015

Lin, Jiehua; Wei, Zhijing; Zhang, Huihui; Shao, Meijia

2013-03-15

206

Controlling morphology, mesoporosity, crystallinity, and photocatalytic activity of ordered mesoporous TiO2 films prepared at low temperature  

NASA Astrophysics Data System (ADS)

Partly ordered mesoporous titania films with anatase crystallites incorporated into the pore walls were prepared at low temperature by spin-coating a microemulsion-based reaction solution. The effect of relative humidity employed during aging of the prepared films was studied using SEM, TEM, and grazing incidence small angle X-ray scattering to evaluate the mesoscopic order, porosity, and crystallinity of the films. The study shows unambiguously that crystal growth occurs mainly during storage of the films and proceeds at room temperature largely depending on relative humidity. Porosity, pore size, mesoscopic order, crystallinity, and photocatalytic activity of the films increased with relative humidity up to an optimum around 75%.

Elgh, Björn; Yuan, Ning; Cho, Hae Sung; Magerl, David; Philipp, Martine; Roth, Stephan V.; Yoon, Kyung Byung; Müller-Buschbaum, Peter; Terasaki, Osamu; Palmqvist, Anders E. C.

2014-11-01

207

Shape Engineerable Single Walled Carbon Nanotube Solid as a Flexible Conducting Mesoporous Material  

Microsoft Academic Search

We present a new form of carbon nanotubes (CNT) material where CNTs are aligned and packed densely in a bulk solid. This single-walled carbon nanotube (SWNT) solid is fabricated from liquid-induced collapse of the sparse as-grown SWNT forest synthesized by super-growth CVD [1], which results in a 20x increase in mass density and a 70x increase in the Vickers hardness

Don N. Futaba; Kenji Hata; Tatsuki Hiraoka; Takeo Yamada; Kohei Mizuno; Yuhei Hayamizu; Tatsunori Namai; Yozo Kakudate; Osamu Tanaike; Hiroaki Hatori; Koji Miyake; Shinya Sasaki; Motoo Yumura; Sumio Iijima

2006-01-01

208

Mesoporous materials and electrochemistry.  

PubMed

Ordered mesoporous materials prepared by the template route have attracted increasing interest from the electrochemists community due to their plenty of unique properties and functionalities that can be effectively exploited in electrochemical devices. This review will cover the whole field of the intersection between electrochemistry and ordered mesoporous materials. The latter are either electronically insulating (silica and some other metal oxides, as well as silica-based organic-inorganic hybrid materials), semi-conducting (metal oxides), or conducting (metals, carbons). The three main intersection areas are: (1) the development/use of electrochemical methods to characterize the properties of mesoporous materials (i.e., charge and mass transfer processes); (2) the generation of mesostructured solids by electro-assisted deposition using appropriate templates; and (3) the application of these novel materials for electrochemical purposes. The most common devices to date are based on a bulk composite or thin film configuration and the resulting electrodes modified with such mesoporous materials have been successfully applied in various fields, including mainly electrochemical sensing and biosensing as well as energy conversion and storage (620 references). PMID:23334166

Walcarius, Alain

2013-05-01

209

Bimodal activated carbons derived from resorcinol-formaldehyde cryogels  

NASA Astrophysics Data System (ADS)

Resorcinol-formaldehyde cryogels prepared at different dilution ratios have been activated with phosphoric acid at 450 °C and compared with their carbonaceous counterparts obtained by pyrolysis at 900 °C. Whereas the latter were, as expected, highly mesoporous carbons, the former cryogels had very different pore textures. Highly diluted cryogels allowed preparation of microporous materials with high surface areas, but activation of initially dense cryogels led to almost non-porous carbons, with much lower surface areas than those obtained by pyrolysis. The optimal acid concentration for activation, corresponding to stoichiometry between molecules of acid and hydroxyl groups, was 2 M l-1, and the acid-cryogel contact time also had an optimal value. Such optimization allowed us to achieve surface areas and micropore volumes among the highest ever obtained by activation with H3PO4, close to 2200 m2 g-1 and 0.7 cm3 g-1, respectively. Activation of diluted cryogels with a lower acid concentration of 1.2 M l-1 led to authentic bimodal activated carbons, having a surface area as high as 1780 m2 g-1 and 0.6 cm3 g-1 of microporous volume easily accessible through a widely developed macroporosity.

Szczurek, Andrzej; Amaral-Labat, Gisele; Fierro, Vanessa; Pizzi, Antonio; Celzard, Alain

2011-06-01

210

Catalysis Today 9395 (2004) 695699 Preparation of stable mesoporous inorganic oxides  

E-print Network

. Keywords: Mesoporous metal oxide; Nano-replication; Mesoporous carbon; Template 1. Introduction It is well and nano-science. There have been several reports concerning the synthesis of mesoporous metal oxidesCatalysis Today 93­95 (2004) 695­699 Preparation of stable mesoporous inorganic oxides via nano

Kim, Ji Man

211

Microcalorimetric Study of Argon, Nitrogen, and Carbon Monoxide Adsorption on Mesoporous Vycor Glass.  

PubMed

The adsorption of argon, nitrogen, and carbon monoxide in porous Vycor glass has been studied by volumetric and microcalorimetric methods and by thermoporometry. Samples with particle sizes ranging from <50 to >200 µm have been selected and treated by sample controlled thermal analysis (SCTA). Subsequent characterization indicates that the particle size has no influence on the pore texture and nature. Thermal treatment, however, modifies the chemical nature of the surface. It would seem that nitrogen and carbon monoxide assume a distinct mean orientation leading to smaller effective cross-sectional areas than those usually accepted. Carbon monoxide clearly distinguishes two different types of adsorption site for samples treated at low temperature. Copyright 1998 Academic Press. PMID:9756665

Torralvo; Grillet; Llewellyn; Rouquerol

1998-10-15

212

Effect of preparation conditions of carbon–silica adsorbents based on mesoporous silica gel Si100 and carbonised glucose on their pore structure  

Microsoft Academic Search

Two series of carbosils were prepared under dynamic (in an open rotary reactor) and static (in a high-pressure autoclave) conditions by pyrolysis of 0.01, 0.03, and 0.05mol of glucose\\/10g of mesoporous silica gel Si-100. Synthesised hybrid adsorbents contained from 5.2 to 21.4wt.% (first series) and 5.6–24.6wt.% (second series) of pyrocarbon, i.e. a high degree of glucose transformation into carbon matter

J Skubiszewska-Zieba; R. Leboda; O. Seledets; V. M. Gun’ko

2003-01-01

213

THERMAL REGENERATION OF ACTIVATED CARBON  

EPA Science Inventory

Ecologically, petrochemical wastes constitute a major hazard since waste materials contain relatively large amounts of non-biodegradable and toxic materials which may be discharged continuously. A three-part experimental study of activated carbon adsorption and thermal regenerati...

214

Silica-templated synthesis of ordered mesoporous tungsten carbide/graphitic carbon composites with nanocrystalline walls and high surface areas via a temperature-programmed carburization route.  

PubMed

Ordered mesostructured tungsten carbide and graphitic carbon composites (WC/C) with nanocrystalline walls are fabricated for the first time by a temperature-programmed carburization approach with phosphotungstic acid (PTA) as a precursor and mesoporous silica materials as hard templates. The mesostructure, crystal phase, and amount of deposited graphitic carbon can be conveniently tuned by controlling the silica template (SBA-15 or KIT-6), carburizing temperature (700-1000 degrees C), the PTA-loading amount, and the carburizing atmosphere (CH(4) or a CH(4)/H(2) mixture). A high level of deposited carbon is favorable for connecting and stabilizing the WC nanocrystallites to achieve high mesostructural regularity, as well as promoting the carburization reaction. Meanwhile, large pore sizes and high mesoporosity of the silica templates can promote WC-phase formation. These novel, ordered, mesoporous WC/C nanocomposites with high surface areas (74-169 m(2) g(-1)), large pore volumes (0.14-0.17 cm(3) g(-1)), narrow pore-size distributions (centered at about 3 nm), and very good oxidation resistance (up to 750 degrees C) have potential applications in fuel-cell catalysts and nanodevices. PMID:19743431

Wu, Zhangxiong; Yang, Yunxia; Gu, Dong; Li, Qiang; Feng, Dan; Chen, Zhenxia; Tu, Bo; Webley, Paul A; Zhao, Dongyuan

2009-12-01

215

Fluorination of "brick and mortar" soft-templated graphitic ordered mesoporous carbons for high  

E-print Network

Li-ion battery cathodes.10 In order to improve the electronic conductivity of so-templated carbons of the cells increases with uorine contents.2­4 Currently available Li/CFx batteries are limited to low rate compared to standard OMCs, making these ideal candidates for supercapacitor and rechargeable Li-ion battery

Geohegan, David B.

216

Mesoporous magnetic carbon nanocomposite fabrics for highly efficient Cr(VI) removal  

E-print Network

of heavy metals from polluted water. 1. Introduction With better awareness of the detrimental effects*a and Suying Wei*ab We have demonstrated that magnetic carbon nanocomposite fabrics prepared by microwave,10 and adsorption11­18 have been employed to remove Cr(VI) from polluted water. However, the maximum permissible

Guo, John Zhanhu

217

Synthesis and characterization of Nano titania particles embedded in mesoporous silica with both high photocatalytic activity and adsorption capability.  

PubMed

TiO(2)-xSiO(2) composites with a high specific surface area (up to 645 m(2)/g), large pore volume, and narrow distribution with average pore sizes ranging from 15 to 20 A have been synthesized by the sol-gel method. The results of characterization by XRD, BET, TEM, FTIR, and DRUV reveal that these TiO(2)-xSiO(2) composites exhibit a core/shell structure of a nano titania/Ti-O-Si species modified titania embedded in mesoporous silica. As compared to pure anatase, the embedding of nano titania particles into the mesoporous silica matrix results in a substantial blue shift of absorption edge from 3.2 to 3.54 eV and higher UV absorption intensity, which are attributed to the formation of the Ti-O-Si species modified titania in the interface between titania and silica. The as-synthesized TiO(2)-xSiO(2) composites exhibit both much higher absorption capability of organic pollutants and better photocatalytic activity for the photooxidation of benzene than pure titania. The better photocatalytic activity of as-synthesized TiO(2)-xSiO(2) composites than pure titania is attributed to their high surface area, higher UV absorption intensity, and easy diffusion of absorbed pollutants on the absorption sites to photogenerated oxidizing radicals on the photoactive sites. PMID:16852519

Li, Yuanzhi; Kim, Sun-Jae

2005-06-30

218

Synthesis and photocatalytic activity of titania monoliths prepared with controlled macro- and mesopore structure.  

PubMed

Herein, we report a one-pot synthesis of crack-free titania monoliths with hierarchical macro-mesoporosity and crystalline anatase walls. Bimodal macroporosity is created through the polymer-induced phase separation of poly(furfuryl alcohol). The cationic polymerization of furfuryl alcohol is performed in situ and subsequently the polymer becomes immiscible with the aqueous phase, which includes titanic acid. Addition of template, Pluronic F127, increases the mesopore volume and diameter of the resulting titania, as the poly(ethylene glycol) block interacts with the titania precursor, leading to assisted assembly of the metal oxide framework. The hydrophobic poly(propylene glycol) micelle core could itself be swollen with monomeric and oligomeric furfuryl alcohol, allowing for mesopores as large as 18 nm. Variations in synthesis parameters affect porosity; for instance furfuryl alcohol content changes the size and texture of the macropores, water content changes the grain size of the titania and Pluronic F127 content changes the size and volume of the mesopore. Morphological manipulation improves the photocatalytic degradation of methylene blue. Light can penetrate several millimeters into the porous monolith, giving these materials possible application in commercial devices. PMID:22775206

Drisko, Glenna L; Zelcer, Andrés; Wang, Xingdong; Caruso, Rachel A; Soler-Illia, Galo J de A A

2012-08-01

219

Self-activated luminescent and mesoporous strontium hydroxyapatite nanorods for drug delivery.  

PubMed

Multifunctional strontium hydroxyapatite (SrHAp) nanorods with luminescent and mesoporous properties have been successfully synthesized by a hydrothermal method. SEM and TEM images indicate that the mesoporous SrHAp samples consist of monodiperse nanorods with lengths of 120-150 nm, diameters of around 20 nm, and the mesopore size of 3-5 nm. The as-obtained SrHAp nanorods show an intense bright blue emission (centered at 432 nm, lifetime 11.6 ns, quantum efficiency: 22%), which might arise from CO(2)(*-) radical impurities in the crystal lattice under long-wavelength UV-light irradiation. Furthermore, the amount of trisodium citrate has an obvious impact on the particle size and the luminescence properties of the products, respectively. The drug storage/release test indicates that the luminescent SrHAp nanorods show a drug loading and controlled release properties for ibuprofen (IBU). Additionally, the emission intensity of SrHAp in the drug carrier system increases with the cumulative released amount of IBU, making the drug release might be easily tracked and monitored by the change of the luminescence intensity. This luminescent material may be potentially applied in the drug delivery and disease therapy fields. PMID:20122726

Zhang, Cuimiao; Li, Chunxia; Huang, Shanshan; Hou, Zhiyao; Cheng, Ziyong; Yang, Piaoping; Peng, Chong; Lin, Jun

2010-04-01

220

Hybrid mesoporous-silica materials functionalized by Pt(II) complexes: correlation between the spatial distribution of the active center, photoluminescence emission, and photocatalytic activity.  

PubMed

[Pt(tpy)Cl]Cl (tpy: terpyridine) was successfully anchored to a series of mesoporous-silica materials that were modified with (3-aminopropyl)triethoxysilane with the aim of developing new inorganic-organic hybrid photocatalysts. Herein, the relationship between the luminescence characteristics and photocatalytic activities of these materials is examined as a function of Pt loading to define the spatial distribution of the Pt complex in the mesoporous channel. At low Pt loading, the Pt complex is located as an isolated species and exhibits strong photoluminescence emission at room temperature owing to metal-to-ligand charge-transfer ((3)MLCT) transitions (at about 530 nm). Energy- and/or electron-transfer from (3)MLCT to O(2) generate potentially active oxygen species, which are capable of promoting the selective photooxidation of styrene derivatives. On the other hand, short Pt···Pt interactions are prominent at high loading and the metal-metal-to-ligand charge-transfer ((3)MMLCT) transition is at about 620 nm. Such Pt complexes, which are situated close to each other, efficiently catalyze H(2)-evolution reactions in aqueous media in the presence of a sacrificial electron donor (EDTA) under visible-light irradiation. This study also investigates the effect of nanoconfinement on anchored guest complexes by considering the differences between the pore dimensions and structures of mesoporous-silica materials. PMID:22865673

Mori, Kohsuke; Watanabe, Kentaro; Terai, Yoshikazu; Fujiwara, Yasufumi; Yamashita, Hiromi

2012-09-01

221

Activated carbon gets revved up  

SciTech Connect

When it comes to adsorption, few products can match the low cost and efficient performance of activated carbon. That`s why the material is so widely used for wastewater treatment. But with processors looking for economical ways to achieve environmental compliance in other operations, the market s taking off in different directions, wit much attention focused on air purification, process water treatment and solvent recovery. It is the opportunity that manufacturers and marketers of activated carbon have been waiting for. All revved up, they are generating new products and regenerating spent carbon, and rounding out their offerings with equipment and technical service. The article discusses new products and applications, increasing regeneration capacity, and competition in the activated carbon industry.

Hairston, D.

1995-11-01

222

A facile one-pot self-assembly approach to incorporate SnOx nanoparticles in ordered mesoporous carbon with soft templating for fuel cells  

NASA Astrophysics Data System (ADS)

Unique SnOx (x = 1,2)/ordered mesoporous carbon nanocomposites (denoted as SnOx/OMC) are firstly synthesized through a ‘one-pot’ synthesis together with the soft template self-assembly approach. The obtained SnOx/OMC nanocomposites with various SnOx contents exhibit uniform pore sizes between 3.9 and 4.2 nm, high specific surface areas between 497 and 595 m2 g-1, and high pore volumes between 0.39 and 0.48 cm3 g-1. With loading of Pt, Pt-SnOx/OMC with relatively low SnOx content exhibits superior electrocatalytic performance, long-term durability, and resistance to CO poisoning for methanol oxidation, as compared to Pt/OMC, PtRu/C and Pt-SnOx/C, which may be attributed not only to the synergetic effect of embedded SnOx, but also to the highly ordered mesostructure with high specific surface areas and large pore volumes affording plenty of surface area for support of Pt nanoparticles. This work supplies an efficient way to synthesize novel ordered mesoporous carbon self-supported metallic oxide as catalyst support and its further potential application to reduce the cost of catalysts in direct methanol fuel cells.

Huang, Yingqiang; Zhai, Zhicheng; Luo, Zhigang; Liu, Yingju; Liang, Zhurong; Fang, Yueping

2014-04-01

223

Solid-solid grinding/templating route to magnetically separable nitrogen-doped mesoporous carbon for the removal of Cu(2+) ions.  

PubMed

N-doped ordered mesoporous carbon materials (NOMC) with 2D hexagonal symmetry structure were synthesized via a facile solid-solid grinding/templating route, in which the ionic liquids (ILs) of 1-cyanoethyl-3-methylimidazolium chloride and SBA-15 were employed as the precursor and hard template, respectively. The as-synthesized NOMC features with a uniform mesoporous size (3.5nm), ropes-like morphology (0.4-1?m in length) and high surface area (803m(2)/g). The quantitative analysis revealed the nitrogen content on the surface of NOMC is 5.5at%. Magnetic iron nanoparticles were successfully embedded into the carbon matrix by introducing iron chloride to the mixture of SBA-15 and ILs during the synthesis process. The NOMC-Fe composite possessed superior adsorption capacity of Cu(2+) ions (23.6mg/g). Kinetic and isothermal analysis demonstrated the strong interactions between Cu(2+) ion and the adsorbent. Furthermore, the composite was magnetically separable from solution under an external magnetic field and thus displayed a superior reusability in the recycling test. PMID:25072134

Chen, Aibing; Yu, Yifeng; Zhang, Yue; Xing, Tingting; Wang, Yanyan; Zhang, Yexin; Zhang, Jian

2014-08-30

224

Activated carbon to the rescue  

SciTech Connect

This article describes the response to pipeline spill of ethylene dichloride (EDC) on the property of an oil company. Activated carbon cleanup proceedure was used. During delivery, changeout, transport, storage, thermal reactivation, and return delivery to the site, the carbon never came into direct contact with operating personnel or the atmosphere. More than 10,000 tones of dredge soil and 50 million gallons of surface water were processed during the emergency response.

Sen, S. [Calgon Carbon Corp., Pittsburgh, PA (United States)

1996-03-01

225

Preparation of Catalytic Nanoparticles in Mesoporous Silica Film for Oriented Growth of Single-Walled Carbon Nanotubes  

E-print Network

acetate and iron acetate. The second one is an incorporation method; mesoporous silica film is prepared unique properties and remarkable potentials as an advanced material. In order to utilize SWNTs widely-coating method at the dipping rate of 2 cm/min. After the coating, the piece was dried in air at 80 o C overnight

Maruyama, Shigeo

226

Enhanced mercuric chloride adsorption onto sulfur-modified activated carbons derived from waste tires.  

PubMed

A number of activated carbons derived from waste tires were further impregnated by gaseous elemental sulfur at temperatures of 400 and 650 degrees C, with a carbon and sulfur mass ratio of 1:3. The capabilities of sulfur diffusing into the micropores of the activated carbons were significantly different between 400 and 650 degrees C, resulting in obvious dissimilarities in the sulfur content of the activated carbons. The sulfur-impregnated activated carbons were examined for the adsorptive capacity of gas-phase mercuric chloride (HgC1) by thermogravimetric analysis (TGA). The analytical precision of TGA was up to 10(-6) g at the inlet HgCl2 concentrations of 100, 300, and 500 microg/m3, for an adsorption time of 3 hr and an adsorption temperature of 150 degrees C, simulating the flue gas emitted from municipal solid waste (MSW) incinerators. Experimental results showed that sulfur modification can slightly reduce the specific surface area of activated carbons. High-surface-area activated carbons after sulfur modification had abundant mesopores and micropores, whereas low-surface-area activated carbons had abundant macropores and mesopores. Sulfur molecules were evenly distributed on the surface of the inner pores after sulfur modification, and the sulfur content of the activated carbons increased from 2-2.5% to 5-11%. After sulfur modification, the adsorptive capacity of HgCl2 for high-surface-area sulfurized activated carbons reached 1.557 mg/g (22 times higher than the virgin activated carbons). The injection of activated carbons was followed by fabric filtration, which is commonly used to remove HgCl2 from MSW incinerators. The residence time of activated carbons collected in the fabric filter is commonly about 1 hr, but the time required to achieve equilibrium is less than 10 min. Consequently, it is worthwhile to compare the adsorption rates of HgCl2 in the time intervals of < 10 and 10-60 min. PMID:22866581

Yuan, Chung-Shin; Wang, Guangzhi; Xue, Sheng-Han; Ie, Iau-Ren; Jen, Yi-Hsiu; Tsai, Hsieh-Hung; Chen, Wei-Jin

2012-07-01

227

Mesoporous ZnCo2O4 nanoflakes with bifunctional electrocatalytic activities toward efficiencies of rechargeable lithium-oxygen batteries in aprotic media  

NASA Astrophysics Data System (ADS)

This study reports the successful synthesis of ternary spinel-based ZnCo2O4 nanoflakes (NFs) with mesoporous architectures via the combination of a urea-assisted hydrothermal reaction with calcination in an air atmosphere. Owing to their favorable mesostructures and desirable bifunctional oxygen reduction and evolution activities, the resulting mesoporous ZnCo2O4 NFs yielded stable cyclability at a cut-off capacity of 500 mA h gcarbon-1 in the case of aprotic Li-O2 batteries.This study reports the successful synthesis of ternary spinel-based ZnCo2O4 nanoflakes (NFs) with mesoporous architectures via the combination of a urea-assisted hydrothermal reaction with calcination in an air atmosphere. Owing to their favorable mesostructures and desirable bifunctional oxygen reduction and evolution activities, the resulting mesoporous ZnCo2O4 NFs yielded stable cyclability at a cut-off capacity of 500 mA h gcarbon-1 in the case of aprotic Li-O2 batteries. Electronic supplementary information (ESI) available: Additional information on set-up of aprotic Li-O2 batteries testing, nitrogen adsorption-desorption analysis, CV measurement, and 1st capacity profiles of ZnCo2O4 NFs and super P-based Li-O2 batteries. See DOI: 10.1039/c3nr04271e

Hung, Tai-Feng; Mohamed, Saad Gomaa; Shen, Chin-Chang; Tsai, Yuan-Quei; Chang, Wen-Sheng; Liu, Ru-Shi

2013-11-01

228

Paracrystalline structure of activated carbons  

NASA Astrophysics Data System (ADS)

Structural studies by means of neutron diffraction of activated carbons, prepared from a polymer of phenol formaldehyde resin by carbonization and activation processes, with variable porosity, are presented. The neutron scattering data were recorded over the range of the scattering vector Q from 2.5 to 500 nm-1. The structure of activated carbons has been described in terms of disordered graphite-like layers with very weak interlayer correlations. The model has been generated by computer simulations and its validity has been tested by comparison of the experimental and calculated intensity functions. Modelling studies have shown that the model containing 3-4 layers each about 2 nm in diameter accounts for the experimental data and that graphite layers are randomly translated and rotated, according to the turbostratic structure. Near-neighbour carbon-carbon distances of about 0.139 nm and 0.154 nm have been determined. The Debye-Waller factor exp (-Q2?2/2) with ? = ?0(r)1/2 suggests a paracrystalline structure within a single layer. The value of the interlayer spacing of 0.36 nm has been found from paracrystalline simulations of the layer arrangement in the c-axis direction. The high quality of the experimental data has enabled determination of the coordination numbers, the interatomic distances and their standard deviations using a curve-fitting procedure over the Q-range from 250 nm to 500 nm, providing structural information about short- and intermediate-range ordering.

Szczygielska, A.; Burian, A.; Dore, J. C.

2001-06-01

229

Enhanced room-temperature hydrogen storage in super-activated carbons: The role of porosity development by activation  

NASA Astrophysics Data System (ADS)

Efficient hydrogen storage with a high density under near-ambient temperature remains a key technical obstacle for a hydrogen economy. Here we demonstrate the enhanced room-temperature hydrogen storage in super-activated carbon materials, which were prepared by carbon dioxide activation of templated porous carbons. These carbon materials possess high specific surface areas of up to 2829 m2/g, large pore volumes of up to 2.34 cm3/g, and hierarchical pore structures consisting of primary micropores with median size in the range of 0.7-1.3 nm and secondary mesopores with the size of 2-4 nm. One of the super-activated carbons exhibits a high hydrogen uptake of 0.95 wt% at 298 K and 80 bar, which is among the highest data reported for the porous carbon materials at room temperature and moderate pressure. The role of porosity development caused by activation in improving the hydrogen storage properties of the carbon materials has been investigated. A close relationship between hydrogen storage capacities and micropore volumes has been found. The microporosity development, especially the rapid increase of narrow pores with the diameters around 1.2 nm, appears to be essential for the enhanced room-temperature hydrogen storage in the super-activated carbons.

Xia, Kaisheng; Hu, Juan; Jiang, Jinhua

2014-10-01

230

Activated carbon gets revved up  

Microsoft Academic Search

When it comes to adsorption, few products can match the low cost and efficient performance of activated carbon. That`s why the material is so widely used for wastewater treatment. But with processors looking for economical ways to achieve environmental compliance in other operations, the market s taking off in different directions, wit much attention focused on air purification, process water

1995-01-01

231

Hydrocarbon recovery with activated carbon  

Microsoft Academic Search

The principle of adsorption has been used extensively to remove water and to recover gasoline from natural gas with gel-type adsorbents in the quick cycle plants. With the gel adsorbents, water will be adsorbed and will actually replace any hydrocarbons being held by the adsorbent. However, with activated carbon, only heavier organic compounds will replace the lighter ones. The recently

Enneking

1968-01-01

232

Hydrothermal synthesis, characterization, photocatalytic activity and dye-sensitized solar cell performance of mesoporous anatase TiO{sub 2} nanopowders  

SciTech Connect

Mesoporous anatase TiO{sub 2} nanopowder was synthesized by hydrothermal method at 130 deg. C for 12 h. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), HRTEM, and Brunauer-Emmett-Teller (BET) surface area. The as-synthesized sample with narrow pore size distribution had average pore diameter about 3-4 nm. The specific BET surface area of the as-synthesized sample was about 193 m{sup 2}/g. Mesoporous anatase TiO{sub 2} nanopowders (prepared by this study) showed higher photocatalytic activity than the nanorods TiO{sub 2}, nanofibers TiO{sub 2} mesoporous TiO{sub 2}, and commercial TiO{sub 2} nanoparticles (P-25, JRC-01, and JRC-03). The solar energy conversion efficiency ({eta}) of the cell using the mesoporous anatase TiO{sub 2} was about 6.30% with the short-circuit current density (Jsc) of 13.28 mA/cm{sup 2}, the open-circuit voltage (Voc) of 0.702 V and the fill factor (ff) of 0.676; while {eta} of the cell using P-25 reached 5.82% with Jsc of 12.74 mA/cm{sup 2}, Voc of 0.704 V and ff of 0.649.

Pavasupree, Sorapong [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Department of Materials and Metallurgical Engineering, Faculty of Engineering, Rajamangala University of Technology Thanyaburi, Klong 6, Pathumthani 12110 (Thailand); Jitputti, Jaturong; Ngamsinlapasathian, Supachai [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan); Yoshikawa, Susumu [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)], E-mail: s-yoshi@iae.kyoto-u.ac.jp

2008-01-08

233

Characterization and photocatalytic activity of mesoporous TiO2 prepared from an ethanol-diethyl ether binary solvent system  

NASA Astrophysics Data System (ADS)

Mesoporous TiO2 nanoparticles were prepared via a sol-gel process using tetra-n-butyl titanate as a titanium source and ethanol-diethyl ether as a binary solvent system at room temperature. The structure of the nanoparticles was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and N2 adsorption-desorption analysis. These mesoporous TiO2 nanoparticles were of anatase form and featured an ordered pore size distribution. The photocatalytic degradation ability of the mesoporous TiO2 nanoparticles was superior to that of commercial TiO2 P-25.

Wang, Wei; Dong, Liang; Wang, Jinpeng; Shi, Xiaomeng; Han, Shiyan

2014-11-01

234

Production and characterization of granular activated carbon from activated sludge  

Microsoft Academic Search

In this study, activated sludge was used as a precursor to prepare activated carbon using sulfuric acid as a chemical activation agent. The effect of preparation conditions on the produced activated carbon characteristics as an adsorbent was investigated. The results indicate that the produced activated carbon has a highly porous structure and a specific surface area of 580 m 2

Z. Al-Qodah; R. Shawabkah

2009-01-01

235

Mesoporous nitrogen-doped carbon-glass ceramic cathodes for solid-state lithium-oxygen batteries.  

PubMed

The composite of nitrogen-doped carbon (N-C) blend with lithium aluminum germanium phosphate (LAGP) was studied as cathode material in a solid-state lithium-oxygen cell. Composite electrodes exhibit high electrochemical activity toward oxygen reduction. Compared to the cell capacity of N-C blend cathode, N-C/LAGP composite cathode exhibits six times higher discharge cell capacity. A significant enhancement in cell capacity is attributed to higher electrocatalytic activity and fast lithium ion conduction ability of LAGP in the cathode. PMID:22148159

Kichambare, Padmakar; Rodrigues, Stanley; Kumar, Jitendra

2012-01-01

236

Magnetic mesoporous materials for removal of environmental wastes  

SciTech Connect

We have synthesized two different magnetic mesoporous materials that can be easily separated from aqueous solutions by applying a magnetic field. Synthesized magnetic mesoporous materials, Mag-SBA-15 (magnetic ordered mesoporous silica) and Mag-OMC (magnetic ordered mesoporous carbon), have a high loading capacity of contaminants due to high surface area of the supports and high magnetic activity due to the embedded iron oxide particles. Application of surface-modified Mag-SBA-15 was investigated for the collection of mercury from water. The mercury adsorption using Mag-SBA-15 was rapid during the initial contact time and reached a steady-state condition, with an uptake of approximately 97% after 7 hours. Application of Mag-OMC for collection of organics from water, using fluorescein as an easily trackable model analyte, was explored. The fluorescein was absorbed into Mag-OMC within minutes and the fluorescent intensity of solution was completely disappeared after an hour. In another application, Mag-SBA-15 was used as a host of tyrosinase, and employed as recyclable catalytic scaffolds for tyrosinase-catalyzed biodegradation of catechol. Tyrosinase aggregates in Mag-SBA-15, prepared in a two step process of tyrosinase adsorption and crosslinking, could be used repeatedly for catechol degradation with no serious loss of enzyme activity. Considering these results of cleaning up water from toxic inorganic, organic and biochemical contaminants, magnetic mesoporous materials have a great potential to be employed for the removal of environmental contaminants and potentially for the application in large-scale wastewater treatment plants.

Kim, Byoung Chan; Lee, Jinwoo; Um, Wooyong; Kim, Jaeyun; Joo, Jin; Lee, Jin Hyung; Kwak, Ja Hun; Kim, Jae Hyun; Lee, Changha; Lee, Hongshin; Addleman, Raymond S.; Hyeon, Taeghwan; Gu, Man Bock; Kim, Jungbae

2011-09-15

237

“ Nafion”-functionalized mesoporous MCM-41 silica shows high activity and selectivity for carboxylic acid esterification and Friedel–Crafts acylation reactions  

Microsoft Academic Search

Hybrid organic–inorganic MCM-41 silicas functionalized with perfluoroalkylsulfonic acid groups analogous to that of Nafion were prepared in a simple single step by a condensation reaction between surface silanol groups of the mesoporous silicas and 1,2,2-trifluoro-2-hydroxy-1-trifluoromethyl-ethane sulfonic acid Beta-sultone. The catalysts showed very high activity for the esterification of long-chain fatty acids with ethanol and high-molecular-weight alcohols with essentially complete selectivity

Mercedes Alvaro; Avelino Corma; Debasish Das; Vicente Fornés; Hermenegildo García

2005-01-01

238

Sol-gel thin-film based mesoporous silica and carbon nanotubes for the determination of dopamine, uric acid and paracetamol in urine.  

PubMed

This work describes the preparation, characterization and application of a hybrid material composed of disordered mesoporous silica (SiO2) modified with multiwalled carbon nanotubes (MWCNTs), obtained by the sol-gel process using HF as the catalyst. This hybrid material was characterized by N2 adsorption-desorption isotherms, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission microscopy (HR-TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). This new hybrid material was used for the construction of a thin film on a glassy carbon electrode. The modified electrode using this material was designated SiO2/MWCNT/GCE. The electrocatalytic properties of the electrode toward dopamine, uric acid and paracetamol oxidation were studied by differential pulse voltammetry. Well-defined and separated oxidation peaks were observed in phosphate buffer solution at pH 7.0, in contrast with the ill-defined peaks observed with unmodified glassy carbon electrodes. The electrode had high sensitivity for the determination of dopamine, uric acid and paracetamol, with the limits of detection obtained using statistical methods, at 0.014, 0.068 and 0.098 µmol L(-1), respectively. The electrode presented some important advantages, including enhanced physical rigidity, surface renewability by polishing and high sensitivity, allowing the simultaneous determination of these three analytes in a human urine sample. PMID:24148467

Canevari, Thiago C; Raymundo-Pereira, Paulo A; Landers, Richard; Benvenutti, Edilson V; Machado, Sérgio A S

2013-11-15

239

Ultrahigh-efficiency photocatalysts based on mesoporous Pt-WO3 nanohybrids.  

PubMed

A reliable nanocasting method has been developed to synthesize mesoporous hybrids of platinum (Pt) nanoparticles decorating tungsten trioxide (WO3). The process began with modification of the SBA-15 template with carbon polymers and Pt nanoparticles accompanied by adsorption of W(6+), which was then converted into m-Pt-WO3 composites by heat treatment and subsequent template removal. The synthetic strategy can be easily extended to prepare other mesoporous nanohybrids with metal oxide loaded precious metal composites. Comprehensive characterizations suggest that the as-developed m-Pt-WO3 nanohybrid exhibits unique properties with mesoporous structure, excellent crystalline structure, and high surface area. When the photocatalytic properties of m-Pt-WO3 nanohybrids were systematically investigated, it was revealed that the m-Pt-WO3 nanohybrids showed great promise for degrading the organic dye under visible light irradiation, which shows an excellent photocatalytic activity that far exceeded those of pure phase mesoporous WO3 and commercial TiO2 (P25), and was 10-fold more active than that of the bulk Pt-WO3 catalyst. The as-developed synthetic route opens up a new avenue for designing mesoporous hybrid materials for various applications benefiting from the unique porous structure, high surface area, and synergistic effects among constituents. PMID:23549423

Wen, Zhenhai; Wu, Wei; Liu, Zhuang; Zhang, Hao; Li, Jinghong; Chen, Junhong

2013-05-14

240

Studies and characterisations of various activated carbons used for carbon\\/carbon supercapacitors  

Microsoft Academic Search

Various activated carbons from the PICA Company have been tested in supercapacitor cells in order to compare their performances. The differences measured in terms of specific capacitance and cell resistance are presented. Porosity measurements made on activated carbon powders and electrode allowed a better understanding of the electrochemical behaviour of these activated carbons. In this way, the PICACTIF SC carbon

J Gamby; P. L Taberna; P Simon; J. F Fauvarque; M Chesneau

2001-01-01

241

Effect of surface phosphorus functionalities of activated carbons containing oxygen and nitrogen on electrochemical capacitance  

PubMed Central

Micro/mesoporous activated carbons containing oxygen and phosphorus heteroatoms were modified by incorporation of nitrogen using melamine and urea precursors. The surface chemistry was analyzed by the means of elemental analysis, XPS, and 31P MAS NMR. The results indicate that upon the incorporation of nitrogen at high temperatures not only new species involving carbon/nitrogen/oxygen are formed but also the phosphorous environment is significantly altered. Both urea and melamine precursors have similar effects on formation of P–N and P–C bonds. These compounds, although present in small but measurable quantities seem to affect the performance of carbons in electrochemical capacitors. With an increase in the heterogeneity of phosphorus containing species and with a decrease in the content pyrophosphates the capacitance increases and the retention ratio of the capacitor is improved. PMID:20354586

Hulicova-Jurcakova, Denisa; Seredych, Mykola; Lu, Gao Qing; Kodiweera, N.K.A.C.; Stallworth, Phillip E.; Greenbaum, Steven; Bandosz, Teresa J.

2009-01-01

242

Analysis of structure and properties of active carbons and their copolymeric precursors  

NASA Astrophysics Data System (ADS)

The relations between chemical structures of BM-DVB copolymers obtained with various monomer molar ratios and their carbonization products were studied. Three porous copolymers 1:4, 1:1, and 4:1 of BM to DVB were the starting materials for preparation of active carbons. Two activation agents were employed: air and phosphoric acid. The carbonization process was performed in the same way in these two cases. To characterize the obtained materials FTIR spectroscopy, thermal and elemental analyses were applied. Porous structure parameters were obtained by means of nitrogen sorption. The results proved that differences in the molar ratio of monomers used in the syntheses of polymeric precursor play a key role for structure and properties of copolymers but have rather small influence on properties of the obtained carbons. Preliminary treatment is more effective during the activation process. The carbons obtained by activation with phosphoric acid are microporous and have well developed porous structures. The air activated carbons are mesoporous with specific surface areas similar to those of polymeric precursors.

Sobiesiak, M.; Gawdzik, B.; Puziy, A. M.; Poddubnaya, O. I.

2010-06-01

243

Sol-gel derived mesoporous cobalt silica catalyst: Synthesis, characterization and its activity in the oxidation of phenol  

NASA Astrophysics Data System (ADS)

Highly mesoporous cobalt silica rice husk catalysts with (5-15 wt.%) Co2+ loading were prepared via a simple sol-gel technique at room temperature. The successful insertion of cobalt ions into silica matrix was evidenced from FT-IR, NMR, XPS and AAS analyses. Preservation of the mesoporosity nature of silica upon incorporating Co2+ was confirmed from the N2-sorption studies. The topography and morphology viewed by TEM analysis differs as the cobalt concentration varies from 5 to 15 wt.%. Parallel pore channels and spherical nanoparticles of 9.44 nm were achieved for cobalt silica catalysts with 10 and 15 wt.% respectively. Cobalt catalysts were active in the liquid-phase oxidation of phenol with H2O2 as an oxygen source. The performances of the catalysts were greatly influenced by various parameters such as reaction temperature, catalyst amount, molar ratio of substrate to oxidant, nature of solvent, metal loading and homogeneous precursor salt. Water served as the best reaction medium for this oxidation system. The regeneration studies confirmed cobalt catalyst could be reused for five cycles without experiencing large loss in the conversion. Both leaching and reusability studies testified that the catalysts were truly heterogeneous.

Andas, Jeyashelly; Adam, Farook; Rahman, Ismail Ab.

2014-10-01

244

Porous carbon nitride nanosheets for enhanced photocatalytic activities.  

PubMed

Porous carbon nitride nanosheets (PCNs) have been prepared for the first time by a simple liquid exfoliation method via probe sonication. These mesoporous nanosheets of around 5 nm in thickness combine several advantages including high surface area, enhanced light absorption and excellent water dispersity. It can be used as a versatile support for co-catalyst loading for photocatalytic dye degradation and water reduction. With 3.8 wt% Co3O4 loaded, PCNs can achieve more efficient photocatalytic degradation of Rhodamine B, compared with non-porous C3N4 nanosheets (CNs), bulk porous C3N4 (PCN) and bulk nonporous C3N4 (CN). With 1.0 wt% Pt loaded, CNs and PCN exhibit 7-8 times enhancement in H2 evolution than CN. Remarkably, PCNs with both porous and nanosheet-like features achieve 26 times higher activity in H2 evolution than CN. These significant improvements in photocatalytic activities can be attributed to the high surface area as well as better electron mobility of the two-dimensional nanostructure. PMID:25362966

Hong, Jindui; Yin, Shengming; Pan, Yunxiang; Han, Jianyu; Zhou, Tianhua; Xu, Rong

2014-12-21

245

Synthesis and photocatalytic activity of co-doped mesoporous TiO{sub 2} on Brij98/CTAB composite surfactant template  

SciTech Connect

Using composite surfactant templates, polyoxyethylene (20) oleyl ether (Brij98) and cetyl trimethyl ammonium bromide (CTAB), as structure-directing agents, N and La co-doped mesoporous TiO{sub 2} complex photocatalysts were synthesized successfully. The micromorphology of co-doped mesoporous TiO{sub 2} samples was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FT-IR), energy-dispersive X-ray spectrometer (EDS) and N{sub 2} adsorption-desorption measurements. The results indicated that the complex photocatalyst prepared with a molar ratio of Brij98:CTAB=1:1 showed a uniform pore size of ca. 7 nm and a high specific surface area (S{sub BET}) of 279.0 m{sup 2} g{sup -1}, and exhibited the highest photocatalytic activity for degradation of papermaking wastewater under ultra-violet light irradiation. The chemical oxygen demand (CODc{sub r}) percent degradation was about 73% in 12 h and chroma percent degradation was 100% in 8 h. - Graphical abstract: CODc{sub r} percent degradation of papermaking wastewater is about 73% after 12 h over the co-doped mesoporous TiO{sub 2} prepared with a molar ratio of Brij98:CTAB=1:1.

Zhang Xiaotong [School of Chemical Engineering, Shandong Institute of Light Industry, and Key Laboratory for Fine Chemicals of Shandong Province, Jinan, 250353 Shandong (China); Zhou Guowei, E-mail: guoweizhou@hotmail.co [School of Chemical Engineering, Shandong Institute of Light Industry, and Key Laboratory for Fine Chemicals of Shandong Province, Jinan, 250353 Shandong (China); Xu Jing; Bai Guangwei; Wang Lei [School of Chemical Engineering, Shandong Institute of Light Industry, and Key Laboratory for Fine Chemicals of Shandong Province, Jinan, 250353 Shandong (China)

2010-06-15

246

Improving the visible light photocatalytic activity of mesoporous TiO2 via the synergetic effects of B doping and Ag loading  

NASA Astrophysics Data System (ADS)

B-doped together with Ag-loaded mesoporous TiO2 (Ag/B-TiO2) was prepared by a two-step hydrothermal method in the presence of boric acid, triblock copolymer surfactant, and silver nitrate, followed by heat treatment. The obtained samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption. It was revealed that all samples consist of highly crystalline anatase with mesoporous structure. For Ag/B-TiO2, B was doped into TiO2 matrix in the form of both interstitial B and substitutional B while Ag was deposited on the surface of B-TiO2 in the form of metallic silver. Compared with the single B-doped or Ag-loaded TiO2 one, mesoporous Ag/B-TiO2 exhibits much higher visible light photocatalytic activity for the degradation of Rhodamine 6G, which can be ascribed to the synergistic effects of B doping and Ag loading by narrowing the band gap of the photocatalyst and preventing the fast recombination of the photogenerated charge carriers, respectively.

Tian, Baozhu; Shao, Zhimang; Ma, Yunfei; Zhang, Jinlong; Chen, Feng

2011-11-01

247

Excellent photocatalytic degradation activities of ordered mesoporous anatase TiO2-SiO2 nanocomposites to various organic contaminants.  

PubMed

Ordered 2-D hexagonal mesoporous TiO(2)-SiO(2) nanocomposites consisted of anatase TiO(2) nanocrystals and amorphous SiO(2) nanoparticles, with large mesochannels and high specific surface areas, have been extensively and detailedly evaluated using various cationic dyes (methylene blue, safranin O, crystal violet, brilliant green, basic fuchsin and rhodamine-6G), anionic dyes (acid fuchsin, orange II, reactive brilliant red X3B and acid red 1) and microcystin-LR. We use mesoporous 80TiO(2)-20SiO(2)-900 for the degradation of cationic dyes and MC-LR, due to the dominant adsorption of SiOH groups and synergistic role of coupled adsorption and photocatalytic oxidation. For anionic dyes, due to the adsorption results predominantly from TiOH groups, our strategy realizes the enhanced photocatalytic oxidation by strong surface acids and larger available specific surface area. Based on this, we prepared 90TiO(2)-10SiO(2)-700 to degrade them. The results show that our samples exhibit excellent degradation activities to all the contaminants, which are much higher than that of P25 photocatalyst. The dyes are not only decolorized promptly but degraded readily as well. It is strongly indicated that our mesoporous nanocomposites are considerably stable and reusable. These results demonstrate that our mesoporous TiO(2)-SiO(2) nanocomposites present extensive and promising application in the fast and highly efficient degradation of various organic pollutants. PMID:22749122

Dong, Weiyang; Sun, Yaojun; Ma, Qingwei; Zhu, Li; Hua, Weiming; Lu, Xinchun; Zhuang, Guoshun; Zhang, Shicheng; Guo, Zhigang; Zhao, Dongyuan

2012-08-30

248

Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction  

NASA Astrophysics Data System (ADS)

A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state 13C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N2 sorption, HR-TEM, and NH3 temperature programmed desorption-thermal conductivity detector (TPD-TCD) analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, ?-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H)-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

Gomes, Ruth; Dutta, Saikat; Bhaumik, Asim

2014-11-01

249

Adsorption of herbicides using activated carbons  

SciTech Connect

This work describes development of a series of novel activated carbon materials and their testing for possible water treatment applications by studying the adsorption of sodium pentachlorphenolate, PCP (a common herbicide/wood preservative). Although the application of activated carbons is an established technology for the treatment of public water supplies, there is a growing need for materials with higher selectivity and adsorptive capacities as well as high abrasion resistance. The materials that will be discussed include extruded wood-derived carbons with novel pore size distributions and high hardness, as well as activated carbon fiber composites. Comparisons will be made with commercial granular water treatment carbons.

Derbyshire, F.; Jagtoyan, M.; Lafferty, C.; Kimber, G. [Univ. of Kentucky, Lexington, KY (United States)

1996-10-01

250

Adsorbed natural gas storage with activated carbons made from Illinois coals and scrap tires  

USGS Publications Warehouse

Activated carbons for natural gas storage were produced from Illinois bituminous coals (IBC-102 and IBC-106) and scrap tires by physical activation with steam or CO2 and by chemical activation with KOH, H3PO4, or ZnCl2. The products were characterized for N2-BET area, micropore volume, bulk density, pore size distribution, and volumetric methane storage capacity (Vm/Vs). Vm/Vs values for Illinois coal-derived carbons ranged from 54 to 83 cm3/cm3, which are 35-55% of a target value of 150 cm3/cm3. Both granular and pelletized carbons made with preoxidized Illinois coal gave higher micropore volumes and larger Vm/Vs values than those made without preoxidation. This confirmed that preoxidation is a desirable step in the production of carbons from caking materials. Pelletization of preoxidized IBC-106 coal, followed by steam activation, resulted in the highest Vm/Vs value. With roughly the same micropore volume, pelletization alone increased Vm/Vs of coal carbon by 10%. Tire-derived carbons had Vm/Vs values ranging from 44 to 53 cm3/cm3, lower than those of coal carbons due to their lower bulk densities. Pelletization of the tire carbons increased bulk density up to 160%. However, this increase was offset by a decrease in micropore volume of the pelletized materials, presumably due to the pellet binder. As a result, Vm/Vs values were about the same for granular and pelletized tire carbons. Compared with coal carbons, tire carbons had a higher percentage of mesopores and macropores.

Sun, J.; Brady, T. A.; Rood, M. J.; Lehmann, C. M.; Rostam-Abadi, M.; Lizzio, A. A.

1997-01-01

251

Diffusion barriers in the kinetics of water vapor adsorption/desorption on activated carbons  

SciTech Connect

The adsorption of water vapor on a highly microporous coconut-shell-derived carbon and a mesoporous wood-derived carbon was studied. These carbons were chosen as they had markedly different porous structures. The adsorption and desorption characteristics of water vapor on the activated carbons were investigated over the relative pressure range p/p{degree} = 0--0.9 for temperatures in the range 285--313 K in a static water vapor system. The adsorption isotherms were analyzed using the Dubinin-Serpinski equation, and this provided an assessment of the polarity of the carbons. The kinetics of water vapor adsorption and desorption were studied with different amounts of preadsorbed water for set changes in pressure relative to the saturated vapor pressure (p/p{degree}). The adsorption kinetics for each relative pressure step were compared and used to calculate the activation energies for the vapor pressure increments. The kinetic results are discussed in relation to their relative position on the equilibrium isotherm and the adsorption mechanism of water vapor on activated carbons.

Harding, A.W.; Foley, N.J.; Thomas, K.M. [Univ. of Newcastle upon Tyne (United Kingdom)] [Univ. of Newcastle upon Tyne (United Kingdom); Norman, P.R.; Francis, D.C. [CBD, Salisbury (United Kingdom)] [CBD, Salisbury (United Kingdom)

1998-07-07

252

One-pot synthesis of nitrogen and sulfur co-doped onion-like mesoporous carbon vesicle as an efficient metal-free catalyst for oxygen reduction reaction in alkaline solution  

NASA Astrophysics Data System (ADS)

Nitrogen and sulfur co-doped onion-like mesoporous carbon vesicle (NS-MCV) with multilayer lamellar structure is synthesized as a metal-free catalyst through a convenient and economical procedure. The synthesized materials are systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectra, nitrogen adsorption-desorption, and X-ray photoelectron spectroscopy (XPS). The characterization results demonstrate that N and S atoms can be successfully doped into the framework of MCV with little impact on the morphology and structure. The NS-MCV manifests a remarkably high electrocatalytic activity as a metal-free electrocatalyst for the oxygen reduction reaction (ORR) with mainly a four-electron transfer pathway. Moreover, in contrast to the commercially available Pt/C catalyst, the NS-MCV shows much better long-term stability and tolerance toward methanol crossover in an alkaline medium. Such excellent performances can be mainly attributed to the synergistic effect arising from the addition of N and S heteroatom, optimized S content and high surface area. The NS-MCV with a simple synthesis method may further exploited as potentially efficient and inexpensive metal-free ORR catalyst materials.

Han, Ce; Bo, Xiangjie; Zhang, Yufan; Li, Mian; Guo, Liping

2014-12-01

253

Self-assembled mesoporous TiO2/carbon nanotube composite with a three-dimensional conducting nanonetwork as a high-rate anode material for lithium-ion battery  

NASA Astrophysics Data System (ADS)

Mesoporous three-dimensional (3D) TiO2/carbon nanotube conductive hybrid nanostructures can be successfully developed using polyethylene oxide (PEO) to modify the surfaces of carbon nanotubes (CNTs). During the synthesis process, PEO acts as not only “bridges” to connect the TiO2 nanoparticles to the CNT surfaces but also as “hosts” to accommodate and stabilize the in situ generated TiO2 particles. As the electrodes for lithium-ion batteries, such mesoporous 3D TiO2/CNT hybrids, demonstrate high Li storage capacity, superior rate performance and excellent long-term cycling stability. They exhibit a reversible specific capacity of 203 mA h g-1 at 100 mA g-1 and a stable capacity retention of 91 mA h g-1 at 8000 mA g-1 (47.6 C) over 100 cycles; they also retain approximately 90% (71 mA h g-1) of their initial discharge capacity after 900 cycles at an extremely high rate of 15,000 mA g-1 (89 C). This facile synthetic strategy to construct mesoporous 3D TiO2/CNT conductive hybrids provides a convenient route that efficiently assembles various inorganic oxide components on the CNTs' surfaces and enables the formation of heterogeneous nanostructures with novel functionalities. In particular, utilizing a conductive 3D CNT network can serve as a promising strategy for developing high-performance electrodes for Li secondary batteries and supercapacitors.

Wang, Jie; Ran, Ran; Tade, Moses O.; Shao, Zongping

2014-05-01

254

Biochar as a precursor of activated carbon  

Microsoft Academic Search

Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium\\u000a hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass\\u000a ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon\\u000a produced by this method has internal surface

R. Azargohar; A. K. Dalai

2006-01-01

255

Biochar As a Precursor of Activated Carbon  

Microsoft Academic Search

Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium\\u000a hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass\\u000a ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon\\u000a produced by this method has internal surface

R. Azargohar; A. K. Dalai

256

Effects of pore structure on the high-performance capacitive deionization using chemically activated carbon nanofibers.  

PubMed

Capacitive deionization (CDI) electrodes were constructed from activated carbon fibers prepared using electrospinning and chemical activation. The CDI efficiencies of these electrodes were studied as a function of their specific surface areas, pore volumes and pore sizes via salt ion adsorption. The specific surface areas increased approximately 90 fold and the pore volume also increased approximately 26 fold with the use of greater amounts of the chemical activation agent. There was a relative increase in the mesopore fraction with higher porosity. A NaCI solution was passed through a prepared CDI system, and the salt removal efficiency of the CDI system was determined by the separation of the Na+ and Cl- ions toward the anode and cathode. The CDI efficiency increased with greater specific surface areas and pore volumes. In addition, the efficiency per unit pore volume increased with a reduction in the micropore fraction, resulting in the suppressed overlapping effect. In conclusion, the obtained improvements in CDI efficiency were mainly attributed to mesopores, but the micropores also played an important role in the high-performance CDI under conditions of high applied potential and high ion concentrations. PMID:24745222

Im, Ji Sun; Kim, Jong Gu; Lee, Young-Seak

2014-03-01

257

Multi-electron redox reaction of an organic radical cathode induced by a mesopore carbon network with nitroxide polymers.  

PubMed

An organic radical based composite cathode comprised of poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA)-Ketjenblack was developed by a simple solvent-less electrode fabrication method. The composite cathode demonstrated a two-electron redox reaction of PTMA that is from an aminoxy anion (n-type) via a radical to an oxoammonium cation (p-type) with the corresponding redox potential at 2.8-3.1 V and 3.5-3.7 V vs. Li/Li(+) when evaluated in lithium half cells. Moreover, the PTMA-Ketjenblack composite electrode exhibits fast electrode reaction kinetics and an enhanced solid electrolyte interface by cyclic voltammetry and electrochemical impedance spectroscopy measurements. These improved electrochemical properties contribute to increased capacity (300 mA h g(-1)), a high rate (50% capacity retention after 100 C rate excursions) and a long cycle life in the cell performance evaluations. Morphological and compositional characterization indicates a unique mesopore network of Ketjenblack with the PTMA matrix, which highly facilitates the interaction between the conductive media and the radical species, resulting in the performance enhancement of the PTMA-Ketjenblack composite cathode. PMID:24202318

Huang, Qian; Choi, Daiwon; Cosimbescu, Lelia; Lemmon, John P

2013-12-28

258

Preparation of diamine modified mesoporous silica on multi-walled carbon nanotubes for the adsorption of heavy metals in aqueous solution  

NASA Astrophysics Data System (ADS)

An effective adsorbent of diamine functionalized mesoporous silica on multi-walled carbon nanotubes (NN-mSiO2@MWCNTs) has been prepared to remove heavy metals in aqueous solution. Structural characterization was conducted by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), N2 adsorption-desorption measurement and X-ray diffraction (XRD), which confirmed the successful grafting of organic moiety on mSiO2@MWCNTs. Metals removal from aqueous solution was examined for Cu(II), Ni(II), Pb(II) and Zn(II). In addition, Cu(II) adsorption process was thoroughly studied from both kinetic and equilibrium points of view. Adsorption kinetics could be well described by pseudo-second-order kinetic equation and exhibited 3-stage intraparticle diffusion mode. Adsorption isotherms fitted well with Langmuir model, exhibiting high adsorption capacity at low concentration. The thermodynamic analysis revealed that the adsorption of Cu(II) onto NN-mSiO2@MWCNTs was endothermic and spontaneous. The prepared adsorbent is expected to be a new material for the removal and recovery of heavy metals from contaminated water.

Yang, Weijie; Ding, Ping; Zhou, Lei; Yu, Jingang; Chen, Xiaoqing; Jiao, Feipeng

2013-10-01

259

Functionalized CMK-3 mesoporous carbon with 2-amino-5-mercapto-1,3,4-thiadiazole for Hg(II) removal from aqueous media.  

PubMed

Ordered mesoporous carbon (CMK-3) was synthesized and functionalized with 2-amino-5-mercapto-1,3,4-thiadiazole groups (AMT-OCMK-3) for Hg(II) removal from aqueous solution. The modified CMK-3 was characterized by X-ray diffraction, N2 adsorption-desorption isotherm, scanning electron microscopy and Fourier transform infrared spectroscopy. The effects of solution pH, contact time, initial Hg(II) concentration and matrix effect were studied. The adsorption data were successfully fitted with the Langmuir model, exhibiting high adsorption capacity of 450.45 mg/g of AMT-OCMK-3. In the solid-phase extraction system a series of experimental parameters such as sample flow rate, sample volume, eluent volume and concentration of the eluent solution have been investigated and established for preconcentration of Hg(II) in aqueous solution. The results showed that the enrichment factor for Hg(II) was 250, the precision (relative standard deviation (RSD), %) for six replicate measurements was 2.05% and the limit of detection for Hg(II) was achieved at 0.17 ?g/L. PMID:25080004

Anbia, Mansoor; Dehghan, Roghaye

2014-07-01

260

Microscopic and mesoscopic structural features of an activated carbon sample, prepared from sorghum via activation by phosphoric acid  

SciTech Connect

Graphical abstract: Display Omitted Highlights: ? Preparation of a new activated carbon sample from sorghum. ? Characterization by adsorption/desorption methods. ? Determination of the structure by synchrotron X-ray diffraction. ? The sample is amorphous and contains distorted graphene fragments. ? A characteristic nanoscale distance is established from the radial distribution function. -- Abstract: An acidic chemical activation procedure has been used for preparing activated carbon with a surface area exceeding 1000 m{sup 2}/g from sorghum. In order to reveal structural features, synchrotron X-ray diffraction measurements have been performed. The structure of the material has been characterized by the total scattering structure factor and the radial distribution function describing short-range arrangement of atoms at distances of the order of a few atomic diameters as well as correlations at a longer scale, of the order of nanometers. The atomic arrangement has been found to be consistent with that of amorphous graphite-like carbon. As far as the mesoscopic structure is concerned, the presence of a characteristic distance is suggested on the basis of the clear nanometer scale oscillations of the radial distribution function, which distance may be assigned as the mesopore size in the material. It is suggested that the approach devized here may later be applied routinely for other activated carbon samples, too, for characterizing atomic and nanoscale order simultaneously.

Temleitner, László [SPring-8, JASRI, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)] [SPring-8, JASRI, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Pusztai, László, E-mail: pusztai.laszlo@wigner.mta.hu [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary)] [Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Rubio-Arroyo, Manuel F.; Aguilar-López, Sergio [Instituto de Quimica, UNAM, Circuito Exterior S/N, Ciudad Universitaria, Coyoacán, México D.F. 04510 (Mexico)] [Instituto de Quimica, UNAM, Circuito Exterior S/N, Ciudad Universitaria, Coyoacán, México D.F. 04510 (Mexico); Klimova, Tatiana [Facultad de Quimica, UNAM, Edif. E, Ciudad Universitaria, Coyoacán, México D.F. 04510 (Mexico)] [Facultad de Quimica, UNAM, Edif. E, Ciudad Universitaria, Coyoacán, México D.F. 04510 (Mexico); Pizio, Orest [Instituto de Quimica, UNAM, Circuito Exterior S/N, Ciudad Universitaria, Coyoacán, México D.F. 04510 (Mexico)] [Instituto de Quimica, UNAM, Circuito Exterior S/N, Ciudad Universitaria, Coyoacán, México D.F. 04510 (Mexico)

2012-12-15

261

ACTIVATED CARBON FROM LIGNITE FOR WATER TREATMENT  

Microsoft Academic Search

High concentrations of humate in surface water result in the formation of excess amounts of chlorinated byproducts during disinfection treatment. These precursors can be removed in water treatment prior to disinfection using powdered activated carbon. In the interest of developing a more cost-effective method for removal of humates in surface water, a comparison of the activities of carbons prepared from

Edwin S. Olson; Daniel J. Stepan

2000-01-01

262

CO oxidation over gold nanocatalyst confined in mesoporous silica  

Microsoft Academic Search

Au nanoparticles embedded within mesoporous silica particles have been prepared and used as catalysts for CO oxidation. The silane APTS (H2N(CH2)3-Si(OMe)3) was used to surface-functionalize mesoporous silica in a direct method. The functionalized mesoporous silica was used to absorb the gold precursor AuCl4? and gold nanoparticles were formed inside the nanochannels after chemical reduction. The catalysts were activated by calcinations,

Yu-Shan Chi; Hong-Ping Lin; Chung-Yuan Mou

2005-01-01

263

Systematical study of depositing nanoparticles and nanowires in mesoporous silica using supercritical carbon dioxide and co-solvents: morphology control, thermodynamics and kinetics of adsorption  

NASA Astrophysics Data System (ADS)

AgNO3 was successfully deposited into mesoporous silica including SBA-15 and KIT-6 using supercritical carbon dioxide as the solvent, ethanol or a mixture of ethanol and ethylene glycol as the co-solvent, followed by calcination after depressurization. A large number of experiments were conducted to find out the most important parameters influencing the metal loading and the morphology of the nanostructure. The morphology was found to vary a lot according to the deposition time, which is interesting, i.e. small nanoparticles, short nanorods, continuous nanowires, and big nanoparticles appeared in succession as the deposition time increased. Besides, the co-solvent was also found to influence significantly the deposition results. The samples prepared using the mixture of ethanol and ethylene glycol as the co-solvent presented the morphology of nanowires, while those prepared using only ethanol as the co-solvent presented a mixed morphology of both nanoparticles and nanowires. The role of ethylene glycol was discussed and a mechanism model demonstrating the formation of Ag nanowires or nanoparticles was proposed. Finally, the adsorption of AgNO3 (adsorbate) from supercritical carbon dioxide and co-solvent (solvent) on the SBA-15 support (adsorbent) was investigated by both experimental and simulating methods. It was found that the adsorption isotherm was well fitted by the Langmuir model, and the kinetic investigation based on a mass differential equation showed that the adsorption reached equilibrium after 10?000 s (about 2.8 h) which was consistent with our experimental result (2.5 h).

Xu, Qin-qin; Wang, Ya-qiong; Wang, Ai-qin; Yin, Jian-zhong; Yu-Liu

2012-07-01

264

Gold stabilized aqueous sols immobilized on mesoporous CeO2-Al2O3 as catalysts for the preferential oxidation of carbon monoxide.  

PubMed

Nanostructured Au/Al(2)O(3)-CeO(2) catalysts with a low content of precious metal (0.9% wt.) were prepared immobilizing two different stabilized Au sols on a high surface area Al(2)O(3)-CeO(2) mixed oxide with a uniform pore size distribution, synthesized by a one-pot methodology. The samples were characterized by elemental analysis, N(2) physisorption, XRPD, TEM and (27)Al-MAS NMR techniques. The catalytic activity of the two samples in the preferential oxidation of CO in excess of H(2) (CO-PROX) was comparatively evaluated in the 35-110 degrees C temperature range. The Au-THPS/AlCe20 sample, prepared immobilizing a sol obtained reducing an aqueous solution of gold tetrachloroaurate salt with bis[tetrakis(hydroxymethyl)phosphonium sulfate], resulted very active and selective at low temperatures and its catalytic activity was correlated with the structural characteristics of the metal particles and of the ordered mesoporous support. PMID:20655539

Storaro, Loretta; Lenarda, Maurizio; Moretti, Elisa; Talon, Aldo; Porta, Francesca; Moltrasio, Bernardo; Canton, Patrizia

2010-10-15

265

Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon  

NASA Astrophysics Data System (ADS)

Carbon-carbon composite of activated carbon and carbon nanofibers have been synthesized by growing Carbon nanofiber (CNF) on Palm shell-based Activated carbon (AC) with Ni catalyst. The composites are in an agglomerated shape due to the entanglement of the defective CNF between the AC particles forming a macroscopic body. The macroscopic size will allow the composite to be used as a stabile catalyst support and liquid adsorbent. The preparation of CNT/AC nanocarbon was initiated by pre-treating the activated carbon with nitric acid, followed by impregnation of 1 wt% loading of nickel (II) nitrate solutions in acetone. The catalyst precursor was calcined and reduced at 300° C for an hour in each step. The catalytic growth of nanocarbon in C2H4/H2 was carried out at temperature of 550° C for 2 hrs with different rotating angle in the fluidization system. SEM and N2 isotherms show the level of agglomeration which is a function of growth density and fluidization of the system. The effect of fluidization by rotating the reactor during growth with different speed give a significant impact on the agglomeration of the final CNF/AC composite and thus the amount of CNFs produced. The macrostructure body produced in this work of CNF/AC composite will have advantages in the adsorbent and catalyst support application, due to the mechanical and chemical properties of the material.

Abdullah, N.; Rinaldi, A.; Muhammad, I. S.; Hamid, S. B. Abd.; Su, D. S.; Schlogl, R.

2009-06-01

266

Making Activated Carbon by Wet Pressurized Pyrolysis  

NASA Technical Reports Server (NTRS)

A wet pressurized pyrolysis (wet carbonization) process has been invented as a means of producing activated carbon from a wide variety of inedible biomass consisting principally of plant wastes. The principal intended use of this activated carbon is room-temperature adsorption of pollutant gases from cooled incinerator exhaust streams. Activated carbon is highly porous and has a large surface area. The surface area depends strongly on the raw material and the production process. Coconut shells and bituminous coal are the primary raw materials that, until now, were converted into activated carbon of commercially acceptable quality by use of traditional production processes that involve activation by use of steam or carbon dioxide. In the wet pressurized pyrolysis process, the plant material is subjected to high pressure and temperature in an aqueous medium in the absence of oxygen for a specified amount of time to break carbon-oxygen bonds in the organic material and modify the structure of the material to obtain large surface area. Plant materials that have been used in demonstrations of the process include inedible parts of wheat, rice, potato, soybean, and tomato plants. The raw plant material is ground and mixed with a specified proportion of water. The mixture is placed in a stirred autoclave, wherein it is pyrolized at a temperature between 450 and 590 F (approximately between 230 and 310 C) and a pressure between 1 and 1.4 kpsi (approximately between 7 and 10 MPa) for a time between 5 minutes and 1 hour. The solid fraction remaining after wet carbonization is dried, then activated at a temperature of 500 F (260 C) in nitrogen gas. The activated carbon thus produced is comparable to commercial activated carbon. It can be used to adsorb oxides of sulfur, oxides of nitrogen, and trace amounts of hydrocarbons, any or all of which can be present in flue gas. Alternatively, the dried solid fraction can be used, even without the activation treatment, to absorb oxides of nitrogen.

Fisher, John W.; Pisharody, Suresh; Wignarajah, K.; Moran, Mark

2006-01-01

267

Activity of Highly Dispersed Co/SBA-15 Catalysts (Low Content) in Carbon Black Oxidation  

NASA Astrophysics Data System (ADS)

Cobalt supported on mesoporous silica SBA-15 (0.75, 1.5 and 3 wt% Co) were used as catalysts for the oxidation of carbon black. Catalysts were characterized by N2 sorption, XRD, TEM and TPR. The catalytic activity in CB oxidation was measured. It has been shown that only small cobalt domains (less than 5 nm) are present on all samples. A homogeneous dispersion was obtained for all catalysts. With increasing cobalt loading, crystalline species start to appear. Using an intermediate contact between the CB and the catalyst, the best activity is that of 0.75Co/SBA-15 catalyst where the oxidation reaches the maximum (Tmax) 68 K before the non-catalyzed reaction. On the same catalyst used in tight contact mode with CB, even if Tmax didn’t decrease for more than additional 12 K but the Ti decreases by 38K and thus starts 83 K before.

Hassan, Nissrine El; Casale, Sandra; Aouad, Samer; Hanein, Theodor; Jabbour, Karam; Chidiac, Elvis; Khoury, Bilal el; Zakhem, Henri El; Nakat, Hanna El

268

Textural and electronic characteristics of mechanochemically activated composites with nanosilica and activated carbon  

NASA Astrophysics Data System (ADS)

Nanosilicas (A-50, A-300, A-500)/activated carbon (AC, SBET = 1520 m2/g) composites were prepared using short-term (5 min) mechanochemical activation (MCA) of powder mixtures in a microbreaker. Smaller silica nanoparticles of A-500 (average diameter dav = 5.5 nm) can more easily penetrate into broad mesopores and macropores of AC microparticles than larger nanoparticles of A-50 (dav = 52.4 nm) or A-300 (dav = 8.1 nm). After MCA of silica/AC, nanopores of non-broken AC nanoparticles remained accessible for adsorbed N2 molecules. According to ultra-soft X-ray emission spectra (USXES), MCA of silica/AC caused formation of chemical bonds Si-O-C; however, Si-C and Si-Si bonds were practically not formed. A decrease in intensity of OK? band in respect to CK? band of silica/AC composites with diminishing sizes of silica nanoparticles is due to both changes in the surface structure of particles and penetration of a greater number of silica nanoparticles into broad pores of AC microparticles and restriction of penetration depth of exciting electron beam into the AC particles.

Gun'ko, V. M.; Zaulychnyy, Ya. V.; Ilkiv, B. I.; Zarko, V. I.; Nychiporuk, Yu. M.; Pakhlov, E. M.; Ptushinskii, Yu. G.; Leboda, R.; Skubiszewska-Zi?ba, J.

2011-11-01

269

MCM-41 mesoporous molecular sieves supported nickel—physico-chemical properties and catalytic activity in hydrogenation of benzene  

Microsoft Academic Search

Siliceous, aluminosilicate and niobosilicate mesoporous molecular sieves of MCM-41 type have been used as matrices for nickel incorporated via the wet impregnation. The N2 adsorption, XRD, H2-TPR and Ni dispersion study were applied for the characterization of the prepared catalysts. The metal–support interaction (MSI) was the highest in Ni\\/NbMCM-41 material as indicated from H2-TPR results, in which the highest dispersion

A Lewandowska; S Monteverdi; M Bettahar; M Ziolek

2002-01-01

270

Structure-dependent catalytic oxidation of H 2S over Na 2CO 3 impregnated carbon aerogels  

Microsoft Academic Search

Na2CO3 impregnated carbon aerogels were developed as high-performance catalysts for low temperature oxidation of H2S. The microporous and mesoporous structures of carbon aerogels were tuned by CO2 activation and the sol–gel conditions, respectively, to investigate their roles in the catalytic performance for H2S oxidation. After desulfurization, micropores were completely blocked and mesopores were partially filled by the oxidation products. The

Qingjun Chen; Jitong Wang; Xiaojun Liu; Zesi Li; Wenming Qiao; Donghui Long; Licheng Ling

2011-01-01

271

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons  

SciTech Connect

This study selected biosolids from a petrochemical wastewater treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl{sub 2}) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl{sub 2}-immersed biosolids pyrolyzed at 500{sup o}C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high. 18 refs., 9 figs., 3 tabs.

Hung-Lung Chiang; Kuo-Hsiung Lin; Chih-Yu Chen; Ching-Guan Choa; Ching-Shyung Hwu; Nina Lai [China Medical University, Taichung (Taiwan). Department of Risk Management

2006-05-15

272

ACTIVATED CARBON FOR PRECIOUS METALS RECOVERY  

Microsoft Academic Search

Guidelines are presented for the selection, handling and regeneration of activated carbon used in gold recovery operations. The guidelines are based on Calgon Carbon Corporation's own investigations and experience gained in working with gold mine operators all over the world. Gold adsorption rate and adsorption capacity are shown to be independent variables thereby requiring testing of both properties when selecting

William D. Faulkner; John E. Urbanic; Robert W. Ruckel

273

Activated carbons and double layer capacitance  

Microsoft Academic Search

The porous structures and electrochemical double layer capacitance of activated carbon microbeads and carbon fibers were investigated using nitrogen gas adsorption and electrochemical constant current cycling (CCC) methods. Porous structural information on pore size distribution (PSD) and surface area were extracted through a gas adsorption analysis program based on density functional theory (DFT). The relation between the porous surface areas

Hang Shi

1996-01-01

274

78 FR 13894 - Certain Activated Carbon From China  

Federal Register 2010, 2011, 2012, 2013

...731-TA-1103 (Review)] Certain Activated Carbon From China Determination On...antidumping duty order on certain activated carbon from China would be likely to...February 2013), entitled Certain Activated Carbon from China: Investigation...

2013-03-01

275

Preparation and application of nanocatalysts via surface functionalization of mesoporous materials  

Microsoft Academic Search

Surface immobilization of active species onto mesoporous materials is gaining importance, especially in the design of functionalized\\u000a mesoporous materials as a nanocatalyst through heterogenization of homogeneous catalytic systems. This article summarizes\\u000a recent work on the synthesis, characterization and catalytic performance of the functionalized mesoporous catalysts performed\\u000a by the present authors. A cationic rhenium(I) complex was encapsulated into mesoporous Al-MCM-41 molecular

Jong-San Chang; Jin-Soo Hwang; Sang-Eon Park

2003-01-01

276

Activated carbons from steam exploded wood  

SciTech Connect

Earlier work has focused on synthesis of activated carbons from hardwood-white oak and yellow poplar. Current studies have been aimed at understanding the role of biopolymer composition and structure on the porosity development in activated carbons. To this end, wood and wood fractions have been produced by steam explosion and extraction methods to provide starting materials with a range of different compositional characteristics. Powdered activated carbons have been synthesized from these precursors by phosphoric acid activation. The pore size distribution of the activated carbons is highly dependent upon the starting material, it varies with steam explosion conditions (ie, severity) as well as with fractionation protocol. Unfractionated steam exploded fibers produce carbons with different pore size distribution than those that have been extracted with water or alkali. The results suggest that there may be good possibilities for producing carbons with controlled porosity through blending appropriate fractions - hence broadening the range of applications for wood carbons. Studies are also under way to examine the ability to form high surface area extrudates from the wood fractions and their blends.

Jagtoyen, M.; Derbyshire, F.; Wright, R.S. [Univ. of Kentucky Center for Applied Energy Research, Lexington, KY (United States)] [and others

1995-12-01

277

A label-free amperometric immunosensor for detection of zearalenone based on trimetallic Au-core/AgPt-shell nanorattles and mesoporous carbon.  

PubMed

A novel label-free amperometric immunosensor is proposed for the ultrasensitive detection of zearalenone (ZEN) based on mesoporous carbon (MC) and trimetallic nanorattles (core/shell particles with movable cores encapsulated in the shells). The nanorattles are composed of special Au-core and imperfect AgPt-shell structure (Au@AgPt). The Au@AgPt nanorattles are loaded onto the MC by physical adsorption. The structure of the Au@AgPt nanorattles was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Energy dispersive X-ray spectroscopy (EDS) confirmed the composition of the synthesized nanorattles. Compared with monometallic and bimetallic nanoparticles (NPs), Au@AgPt nanorattles show a higher electron transfer rate due to the synergistic effect of the Au, Ag and Pt NPs. MC further improves the sensitivity of the immunosensor because of its extraordinarily large specific surface area, suitable pore arrangement and outstanding conductivity. The large specific surface area of MC and MC@Au@AgPt were characterized by the BET method. ZEN antibodies are immobilized onto the nanorattles via Ag-NH2 bonds and Pt-NH2 bonds. Cyclic voltammetry and square wave voltammetry were used to characterize the recognizability of ZEN. Under optimum experimental conditions, the proposed immunosensor exhibited a low detection limit (1.7pgmL(-1)), a wide linear range (from 0.005 to 15ngmL(-1)) as well as good stability, reproducibility and selectivity. The sensor can be used in clinical analysis. PMID:25261897

Liu, Lei; Chao, Yingjun; Cao, Wei; Wang, Yulan; Luo, Chuannan; Pang, Xuehui; Fan, Dawei; Wei, Qin

2014-10-17

278

Gas Adsorption by Activated and Impregnated Carbons.  

National Technical Information Service (NTIS)

HCN/H2O mixed vapor isotherms were measured on BPL activated and ASC whetlerite carbons maintaining an essentially constant relative water pressure and varying the relative HCN pressure. Chemisorption data on ASC whetlerite showed water vapor retention va...

G. B. Freeman, P. J. Reucroft

1977-01-01

279

ACTIVATED CARBON ADSORPTION OF TRACE ORGANIC COMPOUNDS  

EPA Science Inventory

Research was conducted to determine how effectively humic substances and the trace contaminants 2-methylisoborneol (MIB), geosmin, the chlorophenols and polynuclear aromatic hydrocarbons were adsorbed by activated carbon under the competitive adsorption conditions encountered in ...

280

Effects of activated carbon cloth surface on organic adsorption in aqueous solutions. Use of statistical methods to describe mechanisms  

SciTech Connect

The adsorption of polluted water is performed by activated carbon fibers. Three kinds of material are compared: microporous and mesoporous cloths and microporous granular activated carbon. These porous solids are characterized by scanning electron microscopy and atomic force microscopy. BET surface areas and porous volumes are determined. Adsorption of a large number of organic compounds is carried out in water onto activated carbon cloths and granules. Kinetic and equilibrium data are expressed in terms of initial velocities and classical model parameters (Freundlich). These adsorbability parameters are then discussed according to solute molecular structures and activated carbon characteristic. The results obtained show that fluid-solid transfer is directly related to surface and porous structure (pore size distribution and pore connection with the external surface of adsorbents). The adsorption data of several aromatics and aliphatics onto a microporous activated carbon cloth are discussed statistically. A quantitative structure-property relationship method is used. Multiple linear regression and neural networks enable the assessment of correlations between the Freundlich adsorption parameter (log K) and molecular structure defined by molecular connectivity indexes. The neutral network architecture is optimized, and results determined by the two statistical methods are compared: the neural network approach seems to give better results than multiple linear regression to assess this kind of relationship between adsorption and adsorbate molecular structure, even though its predictive ability is low. From a variable analysis, the results are discussed in terms of adsorbate positions at the adsorbent surface and mechanisms of interaction between solutes and an activated carbon surface are proposed.

Brasquet, C.; Le Cloirec, P.

1999-08-31

281

Adsorption of herbicides using activated carbons  

SciTech Connect

This paper describes the results of research in which novel activated carbons have been examined for their efficacy in water treatment and, specifically, for the adsorption of a common herbicide and wood preservative, sodium pentachlorophenolate. To place this work in context, the introduction will discuss first some of the considerations of using activated carbons for water treatment, and then certain aspects of the authors research that has led to this particular topic.

Derbyshire, F.; Jagtoyen, M.; Lafferty, C.; Kimber, G. [Univ. of Kentucky, Lexington, KY (United States)

1996-12-31

282

Biochar as a precursor of activated carbon.  

PubMed

Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon produced by this method has internal surface area at least 50 times than that of the precursor and is highly microporous, which is also confirmed by scanning electron microscopy analysis. Fourier-transform infrared spectroscopy analysis showed development of aromatization in the structure of activated carbon. X-ray diffraction data indicated the formation of small, two-dimensional graphite-like structure at high temperatures. Thermogravimetric study showed that when potassium hydroxide to biochar mass ratio was more than one, the weight loss decreased. PMID:16915686

Azargohar, R; Dalai, A K

2006-01-01

283

Biochar as a precursor of activated carbon.  

PubMed

Biochar was evaluated as a precursor of activated carbon. This product was produced by chemical activation using potassium hydroxide. The effects of operating conditions of activation process, such as temperature, activating agent to biochar mass ratio, and nitrogen flow rate, on the textural and chemical properties of the product were investigated. Activated carbon produced by this method has internal surface area at least 50 times than that of the precursor and is highly microporous, which is also confirmed by scanning electron microscopy analysis. Fourier-transform infrared spectroscopy analysis showed development of aromatization in the structure of activated carbon. X-ray diffraction data indicated the formation of small, two-dimensional graphite-like structure at high temperatures. Thermogravimetric study showed that when potassium hydroxide to biochar mass ratio was more than one, the weight loss decreased. PMID:18563652

Azargohar, R; Dalai, A K

2006-03-01

284

Activated Carbons From Grape Seeds By Chemical Activation With Potassium Carbonate And Potassium Hydroxide  

NASA Astrophysics Data System (ADS)

Activated carbons were produced from grape seed using either potassium carbonate (K2CO3) or potassium hydroxide (KOH). The carbonization experiments were accomplished at 600 and 800 °C. The effects of the experimental conditions (i.e., type of activation reagents, reagent concentrations, and carbonization temperatures) on the yields and the properties of these activated carbons were analyzed under identical conditions. An increase in the temperature at the same concentrations for both K2CO3 and KOH led to a decrease in the yields of the activated carbons. The lowest activated carbon yields were obtained at 800 °C at the highest reagent concentration (100 wt%) for both K2CO3 and KOH. The activated carbon with the highest surface area of 1238 m2g-1 was obtained at 800 °C in K2CO3 concentration of 50 wt% while KOH produced the activated carbon with the highest surface area of 1222 m2g-1 in a concentration of 25wt% at 800 °C. The obtained activated carbons were mainly microporous.

Okman, Irem; Karagöz, Selhan; Tay, Turgay; Erdem, Murat

2014-02-01

285

Nanospace engineering of KOH activated carbon  

NASA Astrophysics Data System (ADS)

This paper demonstrates that nanospace engineering of KOH activated carbon is possible by controlling the degree of carbon consumption and metallic potassium intercalation into the carbon lattice during the activation process. High specific surface areas, porosities, sub-nanometer (<1 nm) and supra-nanometer (1-5 nm) pore volumes are quantitatively controlled by a combination of KOH concentration and activation temperature. The process typically leads to a bimodal pore size distribution, with a large, approximately constant number of sub-nanometer pores and a variable number of supra-nanometer pores. We show how to control the number of supra-nanometer pores in a manner not achieved previously by chemical activation. The chemical mechanism underlying this control is studied by following the evolution of elemental composition, specific surface area, porosity, and pore size distribution during KOH activation and preceding H3PO4 activation. The oxygen, nitrogen, and hydrogen contents decrease during successive activation steps, creating a nanoporous carbon network with a porosity and surface area controllable for various applications, including gas storage. The formation of tunable sub-nanometer and supra-nanometer pores is validated by sub-critical nitrogen adsorption. Surface functional groups of KOH activated carbon are studied by microscopic infrared spectroscopy.

Romanos, J.; Beckner, M.; Rash, T.; Firlej, L.; Kuchta, B.; Yu, P.; Suppes, G.; Wexler, C.; Pfeifer, P.

2012-01-01

286

Carbon activation diagnostic for tertiary neutron measurements  

NASA Astrophysics Data System (ADS)

The yield of tertiary neutrons with energies greater than 20 MeV has been proposed to determine the high ?R of inertial confinement fusion targets. The activation of carbon is a valuable measurement technique because of its high reaction threshold, the availability of high-purity samples, and relatively low cost. The 12C(n,2n)11C reaction has a Q value of 18.7 MeV, well above the 14.1 MeV primary DT neutron energy. The isotope 11C decays with a half-life of 20.3 min and emits a positron, resulting in the production of two back-to-back, 511 keV gamma rays upon annihilation. The positron decay of 11C is nearly identical to the copper decay used in the activation measurements of 14.1 MeV primary DT yields; therefore, the present copper activation gamma-detection system can be used to detect the tertiary-produced carbon activation. Because the tertiary neutron yield is more than six orders of magnitude lower than primary neutron yield, the carbon activation diagnostic requires ultrapure carbon samples, free from any positron-emitting contamination. In recent years we have developed carbon purification, packaging, and handling procedures that minimize the contamination signal to a level low enough to use carbon activation for tertiary neutron measurements in direct-drive implosion experiments with DT cryogenic targets on OMEGA. Experimental results of contamination measurements in carbon samples performed on high-neutron-yield shots on OMEGA in 2001-2002 will be presented. A concept for implementing a carbon activation system on the National Ignition Facility (NIF) will be discussed.

Glebov, V. Yu.; Stoeckl, C.; Sangster, T. C.; Meyerhofer, D. D.; Radha, P. B.; Padalino, S.; Baumgart, L.; Colburn, R.; Fuschino, J.

2003-03-01

287

Bromate removal during transition from new granular activated carbon (GAC) to biological activated carbon (BAC)  

Microsoft Academic Search

Bromate removal by activated carbon after ozonation is a subject of concern, since bromate is commonly found in the ozonation of bromide-containing water. Though new GAC (granular activated carbon) shows the capacity to reduce bromate to bromide, in the long-term use of GAC following ozonation, its bromate removal rate apparently decreases during transition from new GAC to BAC (biological activated

Mari Asami; Takako Aizawa; Takayuki Morioka; Wataru Nishijima; Akihisa Tabata; Yasumoto Magara

1999-01-01

288

Preparation of oil palm empty fruit bunch-based activated carbon for removal of 2,4,6-trichlorophenol: optimization using response surface methodology.  

PubMed

The effects of three preparation variables: CO(2) activation temperature, CO(2) activation time and KOH:char impregnation ratio (IR) on the 2,4,6-trichlorophenol (2,4,6-TCP) uptake and carbon yield of the activated carbon prepared from oil palm empty fruit bunch (EFB) were investigated. Based on the central composite design, two quadratic models were developed to correlate the three preparation variables to the two responses. The activated carbon preparation conditions were optimized using response surface methodology by maximizing both the 2,4,6-TCP uptake and activated carbon yield within the ranges studied. The optimum conditions for preparing activated carbon from EFB for adsorption of 2,4,6-TCP were found as follows: CO(2) activation temperature of 814 degrees C, CO(2) activation time of 1.9h and IR of 2.8, which resulted in 168.89 mg/g of 2,4,6-TCP uptake and 17.96% of activated carbon yield. The experimental results obtained agreed satisfactorily with the model predictions. The activated carbon prepared under optimum conditions was mesoporous with BET surface area of 1141 m(2)/g, total pore volume of 0.6 cm(3)/g and average pore diameter of 2.5 nm. The surface morphology and functional groups of the activated carbon were respectively determined from the scanning electron microscopy and Fourier transform infrared analysis. PMID:18977086

Hameed, B H; Tan, I A W; Ahmad, A L

2009-05-30

289

Microwave-assisted regeneration of activated carbon.  

PubMed

Microwave heating was used in the regeneration of methylene blue-loaded activated carbons produced from fibers (PFAC), empty fruit bunches (EFBAC) and shell (PSAC) of oil palm. The dye-loaded carbons were treated in a modified conventional microwave oven operated at 2450 MHz and irradiation time of 2, 3 and 5 min. The virgin properties of the origin and regenerated activated carbons were characterized by pore structural analysis and nitrogen adsorption isotherm. The surface chemistry was examined by zeta potential measurement and determination of surface acidity/basicity, while the adsorptive property was quantified using methylene blue (MB). Microwave irradiation preserved the pore structure, original active sites and adsorption capacity of the regenerated activated carbons. The carbon yield and the monolayer adsorption capacities for MB were maintained at 68.35-82.84% and 154.65-195.22 mg/g, even after five adsorption-regeneration cycles. The findings revealed the potential of microwave heating for regeneration of spent activated carbons. PMID:22728787

Foo, K Y; Hameed, B H

2012-09-01

290

New mesoporous perovskite ZnTiO 3 and its excellent catalytic activity in liquid phase organic transformations  

Microsoft Academic Search

A new mesoporous perovskite ZnTiO3 material has been synthesized by the evaporation-induced self-assembly (EISA) method using non-ionic surfactant Pluronic P123 as template. After calcination of the dried gel of equimolar concentrations of Zn(II) and Ti(IV) at 673K, a new perovskite mesophase of ZnTiO3 (MZT-11) formed, having highly crystalline cubic ZnTiO3 pore wall. Interestingly, in the absence of P123 but otherwise

Nabanita Pal; Manidipa Paul; Asim Bhaumik

2011-01-01

291

Nanocasted synthesis of mesoporous metal oxides and mixed oxides from mesoporous cubic (Ia3d) vinylsilica.  

PubMed

Mesoporous metal oxides and mixed oxides, such as NiO, CeO2, Cr2O3, Fe203, Mn2O3, NiFe2O4 and Ce(x)Zr(1-x)O2 (x=0.8 and 0.6) have been synthesized by nanocasting from mesoporous cubic (la3d) vinyl-functionalized silica (vinylsilica). Their structural properties were characterized by XRD, TEM, N2-sorption and Raman spectra. Thus-prepared mesoporous materials possess a high BET surface area (110-190 m2g(-1)), high pore volume (0.25-0.40 cm3g(-1)) and relatively ordered structures. The catalytic properties of Cr2O3 were tested in the oxidation of toluene. The mesoporous Cr2O3 exhibits unusually high catalytic activity in the complete oxidation of toluene as compared with commercial Cr2O3. PMID:19198284

Wang, Yangang; Wang, Yanqin; Liu, Xiaohui; Guo, Yun; Guo, Yanglong; Lu, Guanzhong; Schüth, Ferdi

2008-11-01

292

TWO-STAGE GRANULAR ACTIVATED CARBON TREATMENT  

EPA Science Inventory

Two 6.3 l/sec (0.15 mgd), two-stage, packed-bed, downflow granular activated carbon pilot plants were operated continuously for 33 months using unfiltered and unchlorinated activated sludge plant effluent. The main objective of the study was to compare the performance of granular...

293

PYROGENIC ACTIVITY OF CARBON-FILTERED WATERS  

EPA Science Inventory

The endotoxin content and pyrogenic response of granular activated carbon (GAC) filtered waters were studied. GAC-filtered secondary effluent from an activated sludge pilot plant contained free endotoxins in the range 6-250 micrograms/l yielding positive pyrogenic responses in 18...

294

Mesoporous Silica Nanoparticle-Stabilized and Manganese-Modified Rhodium Nanoparticles as Catalysts for Highly Selective Synthesis of Ethanol and Acetaldehyde from Syngas  

SciTech Connect

Well-defined and monodispersed rhodium nanoparticles as small as approximately 2?nm were encapsulated in?situ and stabilized in a mesoporous silica nanoparticle (MSN) framework during the synthesis of the mesoporous material. Although both the activity and selectivity of MSN-encapsulated rhodium nanoparticles in CO hydrogenation could be improved by the addition of manganese oxide as expected, the carbon selectivity for C2 oxygenates (including ethanol and acetaldehyde) was unprecedentedly high at 74.5?% with a very small amount of methanol produced if rhodium nanoparticles were modified by manganese oxide with very close interaction.

Huang, Yulin; Deng, Weihua; Guo, Enruo; Chung, Po-Wen; Chen, Senniang; Trewyn, Brian; Brown, Robert; Lin, Victor

2012-03-30

295

Adsorption studies of methylene blue and phenol onto vetiver roots activated carbon prepared by chemical activation.  

PubMed

Vetiver roots have been utilized for the preparation of activated carbon (AC) by chemical activation with different impregnation ratios of phosphoric acid, X(P) (gH(3)PO(4)/g precursor): 0.5:1; 1:1 and 1.5:1. Textural characterization, determined by nitrogen adsorption at 77K shows that mixed microporous and mesoporous structures activated carbons (ACs) with high surface area (>1000 m(2)/g) and high pore volume (up to 1.19 cm(3)/g) can be obtained. The surface chemical properties of these ACs were investigated by X-ray photoelectron spectroscopy (XPS) and Boehm titration. Their textural and chemical characteristics were compared to those of an AC sample obtained by steam activation of vetiver roots. Classical molecules used for characterizing liquid phase adsorption, phenol and methylene blue (MB), were used. Adsorption kinetics of MB and phenol have been studied using commonly used kinetic models, i.e., the pseudo-first-order model, the pseudo-second-order model, the intraparticle diffusion model and as well the fractal, BWS (Brouers, Weron and Sotolongo) kinetic equation. The correlation coefficients (R(2)) and the normalized standard deviation Deltaq (%) were determined showing globally, that the recently derived fractal kinetic equation could best describe the adsorption kinetics for the adsorbates tested here, indicating a complex adsorption mechanism. The experimental adsorption isotherms of these molecules on the activated carbon were as well analysed using four isotherms: the classical Freundlich, Langmuir, Redlich-Peterson equations, but as well the newly published deformed Weibull Brouers-Sotolongo isotherm. The results obtained from the application of the equations show that the best fits were achieved with the Brouers-Sotolongo equation and with the Redlich-Peterson equation. Influence of surface functional groups towards MB adsorption is as well studied using various ACs prepared from vetiver roots and sugar cane bagasse. Opposite effects governing MB and phenol adsorption mechanism on ACs are demonstrated. The various effects involved in adsorption mechanisms of each molecule are demonstrated. PMID:19118948

Altenor, Sandro; Carene, Betty; Emmanuel, Evens; Lambert, Jacques; Ehrhardt, Jean-Jacques; Gaspard, Sarra

2009-06-15

296

High-temperature-stable and regenerable catalysts: platinum nanoparticles in aligned mesoporous silica wells.  

PubMed

We report the synthesis, structural characterization, thermal stability study, and regeneration of nanostructured catalysts made of 2.9 nm Pt nanoparticles sandwiched between a 180 nm SiO2 core and a mesoporous SiO2 shell. The SiO2 shell consists of 2.5 nm channels that are aligned perpendicular to the surface of the SiO2 core. The nanostructure mimics Pt nanoparticles that sit in mesoporous SiO2 wells (Pt@MSWs). By using synchrotron-based small-angle X-ray scattering, we were able to prove the ordered structure of the aligned mesoporous shell. By using high-temperature cyclohexane dehydrogenation as a model reaction, we found that the Pt@MSWs of different well depths showed stable activity at 500 °C after the induction period. Conversely, a control catalyst, SiO2 -sphere-supported Pt nanoparticles without a mesoporous SiO2 shell (Pt/SiO2 ), was deactivated. We deliberately deactivated the Pt@MSWs catalyst with a 50 nm deep well by using carbon deposition induced by a low H2 /cyclohexane ratio. The deactivated Pt@MSWs catalyst was regenerated by calcination at 500 °C with 20 % O2 balanced with He. After the regeneration treatments, the activity of the Pt@MSWs catalyst was fully restored. Our results suggest that the nanostructured catalysts-Pt nanoparticles confined inside mesoporous SiO2 wells-are stable and regenerable for treatments and reactions that require high temperatures. PMID:24039118

Xiao, Chaoxian; Maligal-Ganesh, Raghu V; Li, Tao; Qi, Zhiyuan; Guo, Zhiyong; Brashler, Kyle T; Goes, Shannon; Li, Xinle; Goh, Tian Wei; Winans, Randall E; Huang, Wenyu

2013-10-01

297

High-Temperature-Stable and Regenerable Catalysts: Platinum Nanoparticles in Aligned Mesoporous Silica Wells  

SciTech Connect

We report the synthesis, structural characterization, thermal stability study, and regeneration of nanostructured catalysts made of 2.9?nm Pt nanoparticles sandwiched between a 180?nm SiO2 core and a mesoporous SiO2 shell. The SiO2 shell consists of 2.5?nm channels that are aligned perpendicular to the surface of the SiO2 core. The nanostructure mimics Pt nanoparticles that sit in mesoporous SiO2 wells (Pt@MSWs). By using synchrotron-based small-angle X-ray scattering, we were able to prove the ordered structure of the aligned mesoporous shell. By using high-temperature cyclohexane dehydrogenation as a model reaction, we found that the Pt@MSWs of different well depths showed stable activity at 500?°C after the induction period. Conversely, a control catalyst, SiO2-sphere-supported Pt nanoparticles without a mesoporous SiO2 shell (Pt/SiO2), was deactivated. We deliberately deactivated the Pt@MSWs catalyst with a 50?nm deep well by using carbon deposition induced by a low H2/cyclohexane ratio. The deactivated Pt@MSWs catalyst was regenerated by calcination at 500?°C with 20?% O2 balanced with He. After the regeneration treatments, the activity of the Pt@MSWs catalyst was fully restored. Our results suggest that the nanostructured catalysts—Pt nanoparticles confined inside mesoporous SiO2 wells—are stable and regenerable for treatments and reactions that require high temperatures.

Xiao, Chaoxian [Ames Laboratory; Maligal-Ganesh, Raghu V. [Ames Laboratory; Li, Tao [Argonne Laboratory; Wi, Zhiyuan [Ames Laboratory; Guo, Zhiyong [Ames Laboratory; Brashler, Kyle T. [Ames Laboratory; Goes, Shannon [Ames Laboratory; Li, Xinle [Ames Laboratory; Goh, Tian Wei [Ames Laboratory; Winans, Randall E. [Argonne Laboratory; Huang, Wenyu [Ames Laboratory

2013-08-22

298

Design and Fabrication of Hierarchically Porous Carbon with a Template-free Method  

NASA Astrophysics Data System (ADS)

Fabrication of hierarchically porous carbon materials (HPCs) with high surface area and pore volume has always been pursued. However, the currently effective template methods and acid/base activation strategies suffer from the drawbacks of either high costs or tedious steps. Herein, HPCs with 3D macro-mesopores and short-range meso-micropores were fabricated via an easy and sustainable two-step method from biomass. Macro-mesopores were constructed by slightly accumulation/aggregation of carbon spheres ranging from 60 nm to 80 nm, providing efficient mass diffusion pathways. Short-range mesopores and micropores with high electrolyte accessibility were developed in these spheres by air activation. The obtained HPCs showed surface area values up to 1306 m2/g and high mesopore volume proportion (63.9%). They demonstrated excellent capacitance and low equivalent series resistance (ESR) as supercapacitor electrode materials, suggesting the efficient diffusion and adsorption of electrolyte ions in the designed hierarchically porous structure.

Gong, Yutong; Wei, Zhongzhe; Wang, Jing; Zhang, Pengfei; Li, Haoran; Wang, Yong

2014-09-01

299

A novel activated carbon for supercapacitors  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer A novel activated carbon was prepared from phenol-melamine-formaldehyde resin. Black-Right-Pointing-Pointer The carbon has large surface area with microporous, and high heteroatom content. Black-Right-Pointing-Pointer Heteroatom-containing functional groups can improve the pseudo-capacitance. Black-Right-Pointing-Pointer Physical and chemical properties lead to the good electrochemical properties. -- Abstract: A novel activated carbon has been prepared by simple carbonization and activation of phenol-melamine-formaldehyde resin which is synthesized by the condensation polymerization method. The morphology, thermal stability, surface area, elemental composition and surface chemical composition of samples have been investigated by scanning electron microscope, thermogravimetry and differential thermal analysis, Brunauer-Emmett-Teller measurement, elemental analysis and X-ray photoelectron spectroscopy, respectively. Electrochemical properties have been studied by cyclic voltammograms, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 6 mol L{sup -1} potassium hydroxide. The activated carbon shows good capacitive behavior and the specific capacitance is up to 210 F g{sup -1}, which indicates that it may be a promising candidate for supercapacitors.

Shen, Haijie [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China)] [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China); Liu, Enhui, E-mail: liuenhui99@sina.com.cn [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China)] [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China); Xiang, Xiaoxia; Huang, Zhengzheng; Tian, Yingying; Wu, Yuhu; Wu, Zhilian; Xie, Hui [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China)] [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China)

2012-03-15

300

Influence of CO{sub 2} activation on hydrogen storage behaviors of platinum-loaded activated carbon nanotubes  

SciTech Connect

In this work, platinum (Pt) metal loaded activated multi-walled carbon nanotubes (MWNTs) were prepared with different structural characteristics for hydrogen storage applications. The process was conducted by a gas phase CO{sub 2} activation method at 1200 {sup o}C as a function of the CO{sub 2} flow time. Pt-loaded activated MWNTs were also formulated to investigate the hydrogen storage characteristics. The microstructures of the Pt-loaded activated MWNTs were characterized by XRD and TEM measurements. The textural properties of the samples were analyzed using N{sub 2} adsorption isotherms at 77 K. The BET, D-R, and BJH equations were used to observe the specific surface areas and the micropore and mesopore structures. The hydrogen storage capacity of the Pt-loaded activated MWNTs was measured at 298 K at a pressure of 100 bar. The hydrogen storage capacity was increased with CO{sub 2} flow time. It was found that the micropore volume of the activated MWNTs plays a key role in the hydrogen storage capacity. -- Graphical abstract: The hydrogen storage capacities of the Pt-loaded activated MWNTs as a function of CO{sub 2} flow time are described. Display Omitted

Lee, Seul-Yi [Department of Chemistry, Inha University, 253, Nam-gu, Incheon 402-751 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.k [Department of Chemistry, Inha University, 253, Nam-gu, Incheon 402-751 (Korea, Republic of)

2010-12-15

301

Reprocessing of used tires into activated carbon and other products  

Microsoft Academic Search

Landfilling used tires which are generated each year in the US is increasingly becoming an unacceptable solution. A better approach, from an environmental and economic standpoint, is to thermally reprocess the tires into valuable products such as activated carbon, other solid carbon forms (carbon black, graphite, and carbon fibers), and liquid fuels. In this study, high surface area activated carbons

Hsisheng Teng; Michael A. Serio; Marek A. Wojtowicz; Rosemary Bassilakis; Peter R. Solomon

1995-01-01

302

Fabrication of activated carbon fibers/carbon aerogels composites by gelation and supercritical drying  

E-print Network

Fabrication of activated carbon fibers/carbon aerogels composites by gelation and supercritical August 2003) Activated carbon fiber/carbon aerogel (ACF/CA) composites were fabricated by gelling. The ACFs can reinforce the related carbon aerogels when they originally have low mass density and are weak

Liu, Jie

303

Modeling the selectivity of activated carbons for efficient separation of hydrogen and carbon dioxide  

E-print Network

the separation of hydrogen and carbon dioxide via adsorption in activated carbons. In the simulations, both hydrogen and carbon dioxide molecules are modeled as Lennard-Jones spheres, and the activated carbons essentially no preference over the two gases and the selectivity of carbon dioxide relative to hydrogen falls

Wu, Jianzhong

304

Activated carbon monoliths for methane storage  

NASA Astrophysics Data System (ADS)

The use of adsorbent storage media for natural gas (methane) vehicles allows for the use of non-cylindrical tanks due to the decreased pressure at which the natural gas is stored. The use of carbon powder as a storage material allows for a high mass of methane stored for mass of sample, but at the cost of the tank volume. Densified carbon monoliths, however, allow for the mass of methane for volume of tank to be optimized. In this work, different activated carbon monoliths have been produced using a polymeric binder, with various synthesis parameters. The methane storage was studied using a home-built, dosing-type instrument. A monolith with optimal parameters has been fabricated. The gravimetric excess adsorption for the optimized monolith was found to be 161 g methane for kg carbon.

Chada, Nagaraju; Romanos, Jimmy; Hilton, Ramsey; Suppes, Galen; Burress, Jacob; Pfeifer, Peter

2012-02-01

305

Synthesis and catalytic applications of combined zeolitic/mesoporous materials  

PubMed Central

Summary In the last decade, research concerning nanoporous siliceous materials has been focused on mesoporous materials with intrinsic zeolitic features. These materials are thought to be superior, because they are able to combine (i) the enhanced diffusion and accessibility for larger molecules and viscous fluids typical of mesoporous materials with (ii) the remarkable stability, catalytic activity and selectivity of zeolites. This review gives an overview of the state of the art concerning combined zeolitic/mesoporous materials. Focus is put on the synthesis and the applications of the combined zeolitic/mesoporous materials. The different synthesis approaches and formation mechanisms leading to these materials are comprehensively discussed and compared. Moreover, Ti-containing nanoporous materials as redox catalysts are discussed to illustrate a potential implementation of combined zeolitic/mesoporous materials. PMID:22259762

Vernimmen, Jarian; Cool, Pegie

2011-01-01

306

Ultrafine single-crystal TiOF2 nanocubes with mesoporous structure, high activity and durability in visible light driven photocatalysis  

NASA Astrophysics Data System (ADS)

Single crystal TiOF2 nanocubes assembled into a mesoporous structure were synthesized by alcoholysis of TiF4 under solvothermal conditions, which displayed spectral response in the visible area owing to the intrinsic narrow energy band gap. Mechanism studies revealed that TiOF2 was formed via consecutive hydrolysis reactions and the H2O produced by condensation between two alcohols played a key role in determining the TiOF2 crystal growth and its transformation to anatase TiO2. The TiOF2 nanocube size could be easily adjusted by changing either alcoholysis time, or solvothermal temperature, or alcohol kind owing to the different H2O production rate and amount. The small-sized TiOF2 nanocubes with large surface area exhibited high activity in photocatalytic degradation of Rhodamine B (RhB) and 4-chlorophenol (4-CP) owing to the enhanced adsorption for reactant molecules and the reduced photoelectron-hole recombination rate. Meanwhile, they also showed strong durability since the mesoporous structure enhanced the stability against either the phase transformation from TiOF2 crystal to anatase TiO2 or the agglomeration of TiOF2 nanocubes.Single crystal TiOF2 nanocubes assembled into a mesoporous structure were synthesized by alcoholysis of TiF4 under solvothermal conditions, which displayed spectral response in the visible area owing to the intrinsic narrow energy band gap. Mechanism studies revealed that TiOF2 was formed via consecutive hydrolysis reactions and the H2O produced by condensation between two alcohols played a key role in determining the TiOF2 crystal growth and its transformation to anatase TiO2. The TiOF2 nanocube size could be easily adjusted by changing either alcoholysis time, or solvothermal temperature, or alcohol kind owing to the different H2O production rate and amount. The small-sized TiOF2 nanocubes with large surface area exhibited high activity in photocatalytic degradation of Rhodamine B (RhB) and 4-chlorophenol (4-CP) owing to the enhanced adsorption for reactant molecules and the reduced photoelectron-hole recombination rate. Meanwhile, they also showed strong durability since the mesoporous structure enhanced the stability against either the phase transformation from TiOF2 crystal to anatase TiO2 or the agglomeration of TiOF2 nanocubes. Electronic supplementary information (ESI) available: Details of the FESEM images, TEM images, N2 adsorption-desorption isotherm, FTIR spectra, TG analysis, XRD patterns, UV-Vis spectra, and model of TiOF2 cubic single crystal cell. See DOI: 10.1039/c3nr04489k

Wang, Jinguo; Cao, Fenglei; Bian, Zhenfeng; Leung, Michael K. H.; Li, Hexing

2013-12-01

307

Characterization and HDS Activity of Mesoporous MoS 2 Catalysts Prepared by in Situ Activation of Tetraalkylammonium Thiomolybdates  

Microsoft Academic Search

Unsupported molybdenum disulfide catalysts with unique morphological pore structure were synthesized from tetraalkylammonium thiometalates precursors by in situ activation during the hydrodesulfurization (HDS) of dibenzothiophene. The precursors used in this study are ammonium thiomolybdate (ATM), tetrapropylammonium thiomolybdate, tetrapentylammonium thiomolybdate, tetrahexylammonium thiomolybdate, tetraheptylammonium thiomolybdate (THepATM), and tetraoctylammonium thiomolybdate. The thermogravimetrical analysis carried out under nitrogen demonstrated that all precursors yield MoS2

G. Alonso; G. Berhault; A. Aguilar; V. Collins; C. Ornelas; S. Fuentes; R. R. Chianelli

2002-01-01

308

Dendrimer Templated Synthesis of One Nanometer Rh and Pt Particles Supported on Mesoporous Silica: Catalytic Activity for Ethylene and Pyrrole Hydrogenation.  

SciTech Connect

Monodisperse rhodium (Rh) and platinum (Pt) nanoparticles as small as {approx}1 nm were synthesized within a fourth generation polyaminoamide (PAMAM) dendrimer, a hyperbranched polymer, in aqueous solution and immobilized by depositing onto a high-surface-area SBA-15 mesoporous support. X-ray photoelectron spectroscopy indicated that the as-synthesized Rh and Pt nanoparticles were mostly oxidized. Catalytic activity of the SBA-15 supported Rh and Pt nanoparticles was studied with ethylene hydrogenation at 273 and 293 K in 10 torr of ethylene and 100 torr of H{sub 2} after reduction (76 torr of H{sub 2} mixed with 690 torr of He) at different temperatures. Catalysts were active without removing the dendrimer capping but reached their highest activity after hydrogen reduction at a moderate temperature (423 K). When treated at a higher temperature (473, 573, and 673 K) in hydrogen, catalytic activity decreased. By using the same treatment that led to maximum ethylene hydrogenation activity, catalytic activity was also evaluated for pyrrole hydrogenation.

Huang, Wenyu; Kuhn, John N.; Tsung, Chia-Kuang; Zhang, Yawen; Habas, Susan E.; Yang, Peidong; Somorjai, Gabor A.

2008-05-09

309

Characterization of Dispersed Heteropoly Acid on Mesoporous Zeolite Using Solid-State P-31 NMR Spin-Lattice Relaxation  

SciTech Connect

Dispersion and quantitative characterization of supported catalysts is a grand challenge in catalytic science. In this paper, heteropoly acid H3PW12O40 (HPA) is dispersed on mesoporous zeolite silicalite-1 derived from hydrothermal synthesis using carbon black nanoparticle templates, and the catalytic activity is studied for 1-butene isomerization. The HPAs supported on conventional zeolite and on mesoporous zeolite exhibit very different activities and thus provide good model systems to investigate the structure dependence of the catalytic properties. The HPA on mesoporous silicalite-1 shows enhanced catalytic activity for 1-butene isomerization, while HPA on conventional silicalite-1 exhibits low activity. To elucidate the structural difference, supported HPA catalysts are characterized using a variety of techniques, including 31P magic angle spinning nuclear magnetic resonance, and are shown to contain a range of species on both mesoporous and conventional zeolites. However, contrary to studies reported in the literature, conventional NMR techniques and chemical shifts alone do not provide sufficient information to distinguish the dispersed and aggregated surface species. The dispersed phase and the nondispersed phase can only be unambiguously and quantitatively characterized using spin-lattice relaxation NMR techniques. The HPA supported on mesoporous zeolite contains a fast relaxation component related to the dispersed catalyst, giving a much higher activity, while the HPA supported on conventional zeolite has essentially only the slow relaxation component with very low activity. The results obtained from this work demonstrate that the combination of spinning sideband fitting and spin-lattice relaxation techniques can provide detailed structural information on not only the Keggin structure for HPA but also the degree of dispersion on the support.

Zhu, Kake; Hu, Jian Z.; She, Xiaoyan; Liu, Jun; Nie, Zimin; Wang, Yong; Peden, Charles HF; Kwak, Ja Hun

2009-09-01

310

USING POWDERED ACTIVATED CARBON: A CRITICAL REVIEW  

EPA Science Inventory

Because the performance of powdered activated carbon (PAC) for uses other than taste and odor control is poorly documented, the purpose of this article is to critically review uses that have been reported (i.e., pesticides and herbicides, synthetic organic chemicals, and trihalom...

311

MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON  

EPA Science Inventory

The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

312

Granular Activated Carbon Filter-Adsorber Systems  

Microsoft Academic Search

The design, operation, and performance of granular activated carbon (GAC) filter-adsorbers were documented and potential problems were identified by means of a survey of operating plants and a review of the literature. It was found that GAC as a total or partial replacement for sand is as effective as conventional filtration media for removing turbidity, provided an appropriate medium size

Sandra L. Graese; Vernon L. Snoeyink; Ramon G. Lee

1987-01-01

313

ENGINEERING BULLETIN: GRANULAR ACTIVATED CARBON TREATMENT  

EPA Science Inventory

Granular activated carbon (GAC) treatment is a physicochemical process that removes a wide variety of contaminants by adsorbing them from liquid and gas streams [1, p. 6-3]. This treatment is most commonly used to separate organic contaminants from water or air; however, it can b...

314

ACTIVATED CARBON TREATMENT OF KRAFT BLEACHING EFFLUENTS  

EPA Science Inventory

The removal of color and organic contaminants by adsorption on activated carbon from the effluent of a kraft pulp bleaching plant was investigated in a pilot plant. The caustic bleach effluent, which contains 80% of the color from pulp bleaching, was decolorized successfully when...

315

Making Activated Carbon for Storing Gas  

NASA Technical Reports Server (NTRS)

Solid disks of microporous activated carbon, produced by a method that enables optimization of pore structure, have been investigated as means of storing gas (especially hydrogen for use as a fuel) at relatively low pressure through adsorption on pore surfaces. For hydrogen and other gases of practical interest, a narrow distribution of pore sizes <2 nm is preferable. The present method is a variant of a previously patented method of cyclic chemisorption and desorption in which a piece of carbon is alternately (1) heated to the lower of two elevated temperatures in air or other oxidizing gas, causing the formation of stable carbon/oxygen surface complexes; then (2) heated to the higher of the two elevated temperatures in flowing helium or other inert gas, causing the desorption of the surface complexes in the form of carbon monoxide. In the present method, pore structure is optimized partly by heating to a temperature of 1,100 C during carbonization. Another aspect of the method exploits the finding that for each gas-storage pressure, gas-storage capacity can be maximized by burning off a specific proportion (typically between 10 and 20 weight percent) of the carbon during the cyclic chemisorption/desorption process.

Wojtowicz, Marek A.; Serio, Michael A.; Suuberg, Eric M.

2005-01-01

316

Adsorption behavior of activated carbon derived from pyrolusite-modified sewage sludge: equilibrium modeling, kinetic and thermodynamic studies.  

PubMed

Activated carbon was developed from sewage sludge using pyrolusite as an additive. It was demonstrated that the removal efficiency of two synthetic dyes (Tracid orange GS and Direct fast turquoise blue GL) by the produced adsorbent was up to 97.6%. The activated carbon with pyrolusite addition had 38.2% higher surface area, 43.8% larger micropore and 54.4% larger mesopore production than ordinary sludge-based activated carbons. Equilibrium adsorption isotherms and kinetics were also investigated based on dyes adsorption tests. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption, and the results fitted well to the Langmuir isotherm. The kinetic data have been analyzed using pseudo-first-order, pseudo-second-order and intraparticle diffusion equation. The experimental data fitted very well with pseudo-second-order kinetic model. Activation energies for the adsorption processes ranged between 8.7 and 19.1 kJ mol 1. Thermodynamic parameters such as standard free energy (deltaG0), standard enthalpy (deltaH0) and standard entropy (deltaS0) were evaluated. The adsorption of these two dyes on the activated carbon was found to be a spontaneous and endothermic process in nature. PMID:22097045

Chen, Yao; Jiang, Wenju; Jiang, Li; Ji, Xiujuan

2011-01-01

317

Targeted thrombolysis by using of magnetic mesoporous silica nanoparticles.  

PubMed

Thrombolytics inevitably led to the risk of hemorrhagic complications due to their non-specific plasminogen activation in treatment of thrombosis. The aim of this study was to determine whether a kind of superparamagnetic mesoporous silica nanoparticle with expanded pore size could achieve effectively targeted thrombolysis. The magnetic mesoporous silica nanoparticles (M-MSNs) with the pore size of 6 nm were prepared by method of the surfactant templating on nano magnetic particles. We investigated the feasibility and efficacy of target thrombolysis with the resultant spheres through fibrin agarose plate assay (FAPA) and a dynamic flow system in vitro. It displayed a 30-fold enhancement of urokinase (UK) loading capacity over the particles without mesoporous layer or the magnetic spheres with mesopores of 3.7 nm. A sustained release behavior was observed due to its larger pore size, higher surface area and narrow mesopore channals contrast to non-mesoporous and small mesopore of 3.7 nm controls. Meanwhile, fibrin agarose plate assay revealed that UK/M-MSNs exhibited a more rapid growth rate of thrombolysis even lasting for 3 days. Additionally, flow model test in vitro suggested this kind of nanoparticle complex enhanced the thrombolysis efficacy by 3.5 fold over the same amount of native UK in 30 min. When compared to non-mesoporous and small mesopore controls, it also represented an extremely higher lysis efficiency (ANOVA, P < 0.01) and a shorter reperfusion time (ANOVA, P < 0.001). Such a magnetic mesoporous silica nanoparticle carrier was expected to be further studied for targeted thrombolytic therapy. PMID:22852472

Wang, Mingqi; Zhang, Jixi; Yuan, Ziming; Yang, Wenzhi; Wu, Qiang; Gu, Hongchen

2012-08-01

318

Preparation and photocatalytic activity of magnetic samarium-doped mesoporous titanium dioxide at the decomposition of methylene blue under visible light  

NASA Astrophysics Data System (ADS)

Preparation of samarium-doped mesoporous titanium dioxide (Sm/MTiO2) coated magnetite (Fe3O4) photocatalysts (Sm/MTiO2/Fe3O4) and their activities under visible light were reported. The catalysts with Sm/MTiO2 shell and a Fe3O4 core were prepared by coating photoactive Sm/MTiO2 onto a magnetic Fe3O4 core through the hydrolysis of tetrabutyltitanate (Ti(OBu)4, TBT) with precursors of Sm(NO3)3 and TBT in the presence of Fe3O4 nanoparticles. The morphological, structural and optical properties of the prepared samples were characterized by BET surface area, transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The effect of Sm ion content on the photocatalytic activity was studied. The photocatalytic activities of obtained photocatalysts under visible light were estimated by measuring the decomposition rate of methylene blue (MB, 50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Sm/MTiO2 was tightly bound to Fe3O4 and could be easily recovered from the medium by a simple magnetic process. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.

Shi, Zhongliang; Lai, Hong; Yao, Shuhua

2012-08-01

319

Single crystalline mesoporous silicon nanowires  

SciTech Connect

Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. These porous nanowires also retain the crystallographic orientation of the wafer from which they are etched. Electron microscopy and diffraction confirm their single-crystallinity and reveal the silicon surrounding the pores is as thin as several nanometers. Confocal fluorescence microscopy showed that the photoluminescence (PL) of these arrays emanate from the nanowires themselves, and their PL spectrum suggests that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices.

Hochbaum, A.I.; Gargas, Daniel; Jeong Hwang, Yun; Yang, Peidong

2009-08-04

320

Templated nanoscale porous carbons.  

PubMed

This manuscript reviews key developments in the important and rapidly expanding area of templated porous carbons. The porosity covered ranges from microporous to mesoporous and macroporous carbons. Two modes of templating, using so-called hard and soft templates, are covered. In particular, for hard templating, zeolite templating generates microporous carbons, mesoporous silicates yield mesoporous carbons, while colloidal particles are replicated to large mesoporous and macroporous carbons. Soft-templating, a more recent phenomenon, mainly generates mesoporous carbons. The full range of pore sizes can therefore now be accessed using hard and soft templates to generate highly ordered nanoscale carbons with well-defined and optimised textural properties. The research area has seen rapid and important developments over the last few years, and this review aims to present the more significant advances. PMID:20648305

Xia, Yongde; Yang, Zhuxian; Mokaya, Robert

2010-05-01

321

Nano Structured Activated Carbon for Hydrogen Storge  

SciTech Connect

Development of a nanostructured synthetic carbons materials that have been synthesized by thermal-decomposition of aromatic rich polyether such as poly(ether ether ketone) (PEEK) is reported. These polymers based nanostructured carbons efficacious for gas adsorption and storage and have Brunauer-Emmett-Teller (BET) surface area of more than 3000 m2/g, and with average pore diameter of < 2nm. Surface-area, pore characteristics, and other critical variables for selecting porous materials of high gas adsorption capacities are presented. Analysis of the fragments evolved under various carbonization temperatures, and the correlation between the activation and carbonization temperatures provides a mechanistic perspective of the pore evolution during activation. Correlations between gas (N2 and H2) adsorption capacity and porous texture of the materials have been established. The materials possess excellent hydrogen storage properties, with hydrogen storage capacity up to 7.4 wt% (gravimetric) and ~ 45 g H2 L-1 (volumetric) at -196oC and 6.0 MPa.

Israel Cabasso; Youxin Yuan

2013-02-27

322

Pilot-scale demonstration of the OSCAR process for high-temperature multipollutant control of coal combustion flue gas, using carbonated fly ash and mesoporous calcium carbonate  

SciTech Connect

A pilot-scale study of the Ohio State Carbonation Ash Reactivation (OSCAR) process was performed to demonstrate the reactivity of two novel calcium-based sorbents toward sulfur and trace heavy metal (arsenic, selenium, and mercury) capture in the furnace sorbent injection (FSI) mode on a 0.365 m{sup 3}/s slipstream of a bituminous coal-fired stoker boiler. The sorbents were synthesized by bubbling CO{sub 2} to precipitate calcium carbonate (a) from the unreacted calcium present in the lime spray dryer ash and (b) from calcium hydroxide slurry that contained a negatively charged dispersant. The heterogeneous reaction between these sorbents and SO{sub 2} gas occurred under entrained flow conditions by injecting fine sorbent powders into the flue gas slipstream. The reacted sorbents were captured either in a hot cyclone (about 650{sup o}C) or in the relatively cooler downstream baghouse (about 230{sup o}C). The baghouse samples indicated about 90% toward sulfation and captured arsenic, selenium and mercury to 800 ppmw, 175 ppmw and 3.6 ppmw, respectively.

Gupta, H.; Thomas, T.J.; Park, A.H.A.; Iyer, M.V.; Gupta, P.; Agnihotri, R.; Jadhav, R.A.; Walker, H.W.; Weavers, L.K.; Butalia, T.; Fan, L.S. [Ohio State University, Columbus, OH (United States)

2007-07-15

323

A dual amplification strategy for ultrasensitive electrochemiluminescence immunoassay based on a Pt nanoparticles dotted graphene-carbon nanotubes composite and carbon dots functionalized mesoporous Pt/Fe.  

PubMed

A facile and sensitive electrochemiluminescence (ECL) immunosensor for the detection of human carcinoembryonic antigen (CEA) was designed. The immunosensor used Pt nanoparticles dotted graphene-carbon nanotubes composites (Pt/Gr-CNTs) as a platform and carbon dots functionalized Pt/Fe nanoparticles (Pt/Fe@CDs) as bionanolabels. The Pt/Gr-CNTs was first synthesized using a facile ultrasonic method to modify the working electrode, which increases the surface area to capture a large amount of primary anti-CEA antibodies as well as improving the electronic transmission rate. The bionanolabels Pt/Fe@CDs prepared through ethanediamine linking, showed good ECL signal amplification performance. The reason is that the Pt/Fe@CDs nanocomposites as signal tags can increase CDs loading per immunoreaction in comparison with single CDs. The approach provided a good linear response range from 0.003 to 600 ng mL(-1) with a low detection limit of 0.8 pg mL(-1). The immunosensor showed good specificity, acceptable stability and reproducibility. Satisfactory results were obtained in the determination of CEA in human serum albumin samples. Hence, the proposed ECL immunosensor could become a promising method for tumor marker detection. PMID:24519411

Deng, Wenping; Liu, Fang; Ge, Shenguang; Yu, Jinghua; Yan, Mei; Song, Xianrang

2014-04-01

324

Gyroidal mesoporous multifunctional nanocomposites via atomic layer deposition  

NASA Astrophysics Data System (ADS)

We demonstrate the preparation of rationally designed, multifunctional, monolithic and periodically ordered mesoporous core-shell nanocomposites with tunable structural characteristics. Three-dimensionally (3D) co-continuous gyroidal mesoporous polymer monoliths are fabricated from a solution-based triblock terpolymer-resol co-assembly and used as the functional templates for the fabrication of free-standing core-shell carbon-titania composites using atomic layer deposition (ALD). The deposition depth into the torturous gyroidal nanonetwork is investigated as a function of ALD conditions and the resulting composites are submitted to different thermal treatments. Results suggest that ALD can homogenously coat mesoporous templates with well defined pore sizes below 50 nm and thicknesses above 10 ?m. Structural tunability like titania shell thickness and pore size control is demonstrated. The ordered nanocomposites exhibit triple functionality; a 3D continuous conductive carbon core that is coated with a crystalline titania shell that in turn is in contact with a 3D continuous mesopore network in a compact monolithic architecture. This materials design is of interest for applications including energy conversion and storage. Gyroidal mesoporous titania monoliths can be obtained through simultaneous titania crystallization and template removal in air.We demonstrate the preparation of rationally designed, multifunctional, monolithic and periodically ordered mesoporous core-shell nanocomposites with tunable structural characteristics. Three-dimensionally (3D) co-continuous gyroidal mesoporous polymer monoliths are fabricated from a solution-based triblock terpolymer-resol co-assembly and used as the functional templates for the fabrication of free-standing core-shell carbon-titania composites using atomic layer deposition (ALD). The deposition depth into the torturous gyroidal nanonetwork is investigated as a function of ALD conditions and the resulting composites are submitted to different thermal treatments. Results suggest that ALD can homogenously coat mesoporous templates with well defined pore sizes below 50 nm and thicknesses above 10 ?m. Structural tunability like titania shell thickness and pore size control is demonstrated. The ordered nanocomposites exhibit triple functionality; a 3D continuous conductive carbon core that is coated with a crystalline titania shell that in turn is in contact with a 3D continuous mesopore network in a compact monolithic architecture. This materials design is of interest for applications including energy conversion and storage. Gyroidal mesoporous titania monoliths can be obtained through simultaneous titania crystallization and template removal in air. Electronic supplementary information (ESI) available: Photographs of flexible templates and the Beneq ALD reactor indicating the different sample positioning. See DOI: 10.1039/c4nr01948b

Werner, Jörg G.; Scherer, Maik R. J.; Steiner, Ullrich; Wiesner, Ulrich

2014-07-01

325

Carbon-deposited TiO2 3D inverse opal photocatalysts: visible-light photocatalytic activity and enhanced activity in a viscous solution.  

PubMed

We for the first time demonstrated carbon-deposited TiO2 inverse opal (C-TiO2 IO) structures as highly efficient visible photocatalysts. The carbon deposition proceeded via high-temperature pyrolysis of phloroglucinol/formaldehyde resol, which had been coated onto the TiO2 IO structures. Carbon deposition formed a carbon layer and doped the TiO2 interface, which synergistically enhanced visible-light absorption. We directly measured the visible-light photocatalytic activity by constructing solar cells comprising the C-TiO2 IO electrode. Photocatalytic degradation of organic dyes in a solution was also evaluated. Photocatalytic dye degradation under visible light was only observed in the presence of the C-TiO2 IO sample and was increased with the content of carbon deposition. The IO structures could be readily decorated with TiO2 nanoparticles to increase the surface area and enhance the photocatalytic activity. Notably, the photocatalytic reaction was found to proceed in a viscous polymeric solution. A comparison of the mesoporous TiO2 structure and the IO TiO2 structure revealed that the latter performed better as the solution viscosity increased. This result was attributed to facile diffusion into the fully connected and low-tortuosity macropore network of the IO structure. PMID:24266769

Lee, Sunbok; Lee, Youngshin; Kim, Dong Ha; Moon, Jun Hyuk

2013-12-11

326

Adsorption of Nonylphenol onto Granular Activated Carbon  

Microsoft Academic Search

The applicability of granular activated carbon (GAC)filtration for the removal of the xeno-estrogenicmicropollutant nonylphenol (NP) is evaluated using batchadsorption data. From the obtained adsorption data, it wasapparent that with contact times of 4 d and 24 hr and GACdosages of 1 and 0.1 g L-1 no saturationof the GAC could be obtained with NP total contaminantloadings up to 10 000

Tom Tanghe; Willy Verstraete

2001-01-01

327

Phenol degradation by microorganisms adsorbed on activated carbon  

Microsoft Academic Search

The phenol degradation by Candida sp. and Pseudomonas sp. immobilized on activated carbon was investigated. Thanks to its great adsorptive surface, activated carbon is suited as supporting material for microorganisms and also provides a high adsorption capacity for phenol.

H. M. Ehrhardt; H. J. Rehm

1985-01-01

328

Purification of Graphite used in Carbon Activation  

NASA Astrophysics Data System (ADS)

Carbon Activation has been developed as a diagnostic to determine the yield of tertiary neutrons. However, copious primary neutrons easily activate positron-emitting contaminants within the disks. To reduce contaminant levels, a thorough purification process has been developed. Detailed packaging and handling procedures are being perfected in order to minimize the gamma signal produced by contaminants. A vacuum oven was used to heat the graphite disks to 1000¢XC @ 200 microns for varying time intervals. The bakeout drove contaminants such as nitrogen, oxygen and hydrocarbons from the disks, which in turn has greatly reduced the number of gamma counts. Careful hermetic packaging procedures have been developed so that the disks do not come in contact with air or other surface contaminants after the bakeout. These techniques have been refined, significantly reducing the contamination signal seen on high-neutron-yield shots on OMEGA. The experimental results of contamination measurements in carbon samples performed in 2001¡V2002 will be presented, as well as the feasibility of implementing a carbon activation system at the National Ignition Facility. Research funded in part by the United States Department of Energy.

Voltz, Katie; Padalino, Stephen; Bamugart, Leigh; Jiang, Hui Ming; Smith, Elizabeth; Colburn, Robyn; Fuschino, Julia

2002-10-01

329

Elastic Pore Structure in Activated Carbon  

NASA Astrophysics Data System (ADS)

Adsorbent materials such as activated carbon and Metal-Organic Frameworks (MOFs) have received significant attention as a potential storage material for hydrogen and natural gas. Typically the adsorbent material is assumed to consist of rigid slit- or cylindrical-shaped pores. Recent work, for MOFs in particular, revealed the importance of the mechanical response of the adsorbent in the presence of an adsorbate. In the absence of an adsorbate the pore structure is defined by the size, shape and inter-molecular interactions of the constituent parts of the solid. Here, we demonstrate the flexibility of pore walls in activated carbon and the effect this has on the pore structure of the bulk samples. The interaction is modeled as a competition between Van der Waals interactions between neighboring walls and a resistance to bending due to the rigidity of graphene. Minimal energy configurations were calculated analytically for a simplified potential and numerically for a more realistic potential. The pore structures are discussed in the context of pore measurements on activated carbon samples.

Connolly, M. J.; Wexler, Carlos

2011-11-01

330

Synthesis of La 3+ doped mesoporous titania with highly crystallized walls  

Microsoft Academic Search

A simple synthetic method to prepare thermally stable La3+ doped mesoporous titania with highly crystallized walls and high photocatalytic activity is reported. The crystalline framework derives from the assembly of nano-anatase particles. La3+ doping is a critical factor to increase the stability and photocatalytic activity of mesoporous titania. The mesoporous materials were characterized by low angle and wide angle X-ray

Shuai Yuan; Qiaorong Sheng; Jinlong Zhang; Feng Chen; Masakazu Anpo; Qinghong Zhang

2005-01-01

331

Silver-containing mesoporous bioactive glass with improved antibacterial properties.  

PubMed

The aim of the present work is the study of the bacteriostatic/bactericidal effect of a silver-containing mesoporous bioactive glass obtained by evaporation-induced self-assembly and successive thermal stabilization. Samples of the manufactured mesophase were characterized by means of transmission electron microscopy and N? adsorption/desorption at 77 K, revealing structural and textural properties similar to SBA-15 mesoporous silica. Glass samples used for bioactivity experiments were put in contact with a standardized, commercially available cell culture medium instead of lab-produced simulated body fluid, and were then characterized by means of X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. All these analyses confirmed the development of a hydroxyl carbonate apatite layer on glass particles. Moreover, the investigated mesostructure showed a very good antibacterial effect against S. aureus strain, with a strong evidence of bactericidal activity already registered at 0.5 mg/mL of glass concentration. A hypothesis about the mechanism by which Ag affects the bacterial viability, based on the intermediate formation of crystalline AgCl, was also taken into account. With respect to what already reported in the literature, these findings claim a deeper insight into the possible use of silver-containing bioactive glasses as multifunctional ceramic coatings for orthopedic devices. PMID:23712538

Gargiulo, Nicola; Cusano, Angela Maria; Causa, Filippo; Caputo, Domenico; Netti, Paolo Antonio

2013-09-01

332

Dual-mesoporous ZSM-5 zeolite with highly b-axis-oriented large mesopore channels for the production of benzoin ethyl ether.  

PubMed

Dual-mesoporous ZSM-5 zeolite with highly b axis oriented large mesopores was synthesized by using nonionic copolymer F127 and cationic surfactant CTAB as co-templates. The product contains two types of mesopores--smaller wormlike ones of 3.3?nm in size and highly oriented larger ones of 30-50?nm in diameter along the b axis--and both of them interpenetrate throughout the zeolite crystals and interconnect with zeolite microporosity. The dual-mesoporous zeolite exhibits excellent catalytic performance in the condensation of benzaldehyde with ethanol and greater than 99?% selectivity for benzoin ethyl ether at room temperature, which can be ascribed to the zeolite lattice structure offering catalytically active sites and the hierarchical and oriented mesoporous structure providing fast access of reactants to these sites in the catalytic reaction. The excellent recyclability and high catalytic stability of the catalyst suggest prospective applications of such unique mesoporous zeolites in the chemical industry. PMID:23775816

Zhou, Xiaoxia; Chen, Hangrong; Zhu, Yan; Song, Yudian; Chen, Yu; Wang, Yongxia; Gong, Yun; Zhang, Guobin; Shu, Zhu; Cui, Xiangzhi; Zhao, Jinjin; Shi, Jianlin

2013-07-22

333

Production of activated carbon from acorns and olive seeds  

Microsoft Academic Search

This study has been designed to produce activated carbon from acorns and olive seeds. The starting materials are low in cost and they are the cause of solid waste pollution problems in Jordan. A chemical procedure is used to produce the required activated carbon. The results indicate that activated carbon produced from acorns compares favorably with that from olive seeds

Walid K Lafi

2001-01-01

334

Studies of activated carbons used in double-layer capacitors  

Microsoft Academic Search

Various kinds of activated carbon materials were investigated by means of nitrogen gas adsorption, AC impedance and constant current discharge techniques. The relation between the intrinsic pore size distribution of activated carbon materials and their electrochemical performance as electrodes of supercapacitor were discussed in detail. Activated carbons with larger pores are found to be more suitable for high power applications.

Deyang Qu; Hang Shi

1998-01-01

335

Hierarchically Structured Sulfur/Carbon Nanocomposite Material for High Energy Lithium Battery  

SciTech Connect

We report herein a hierarchically structured sulfur-carbon (S/C) nanocomposite material as the high surface-area cathode for rechargeable lithium batteries. A porous carbon with a uniform distribution of mesopores of 7.3 nm has been synthesized through a soft-template synthesis method. The potassium hydroxide activation of this mesoporous carbon results in a bimodal porous carbon with added microporosity of less than 2 nm to the existing mesopores without deterioration of the integrity of the original mesoporous carbon. Elemental sulfur has been loaded to the micropores through a solution infiltration method. The resulted S/C composites with various loading level of sulfur have a high surface areas and large internal porosities. These materials have been tested as novel cathodes for Li/S batteries. The results show that the cyclability and the utilization of sulfur in the Li/S batteries have been significantly improved. The large internal porosity and surface area of the micro-mesoporous carbon is essential for retaining sulfur in the cathode and therefore maximizing the capacity and lifespan of the cathode.

Liang, Chengdu [ORNL] [ORNL; Dudney, Nancy J [ORNL] [ORNL; Howe, Jane Y [ORNL] [ORNL

2009-01-01

336

Phosphotungstic acid anchored to amino-functionalized core-shell magnetic mesoporous silica microspheres: a magnetically recoverable nanocomposite with enhanced photocatalytic activity.  

PubMed

H(3)PW(12)O(40) was successfully anchored to the surface of amino-functionalized Fe(3)O(4)@SiO(2)@meso-SiO(2) microspheres by means of chemical bonding to aminosilane groups, aiming to remove unwanted organic compounds from aqueous media. The resultant multifunctional microspheres were thoroughly characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, infrared spectroscopy, inductively coupled plasma, and N(2) adsorption-desorption. The as-prepared microspheres possess unique properties including high magnetization (46.8 emu g(-1)), large BET surface area (135 m(2) g(-1)), and highly open mesopores (~5.0 nm), and H(3)PW(12)O(40) loading is calculated to be ~16.8%; and as a result, the as-prepared microspheres exhibit enhanced performance in degrading dyes under UV irradiation compared with pure H(3)PW(12)O(40). Additionally, the photocatalyst can be easily recycled using an external magnetic field without losing the photocatalytic activity. PMID:23083769

Zhao, Liang; Chi, Yue; Yuan, Qing; Li, Nan; Yan, Wenfu; Li, Xiaotian

2013-01-15

337

Mesoporous aluminum phosphite  

NASA Astrophysics Data System (ADS)

High surface area pure mesoporous aluminum-phosphorus oxide-based derivatives have been synthesized through an S +I - surfactant-assisted cooperative mechanism by means of a one-pot preparative procedure from aqueous solution and starting from aluminum atrane complexes and phosphoric and/or phosphorous acids. A soft chemical extraction procedure allows opening the pore system of the parent as-prepared materials by exchanging the surfactant without mesostructure collapse. The nature of the pore wall can be modulated from mesoporous aluminum phosphate (ALPO) up to total incorporation of phosphite entities (mesoporous aluminum phosphite), which results in a gradual evolution of the acidic properties of the final materials. While phosphate groups in ALPO act as network building blocks (bridging Al atoms), the phosphite entities become basically attached to the pore surface, what gives practically empty channels. The mesoporous nature of the final materials is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N 2 adsorption-desorption isotherms. The materials present regular unimodal pore systems whose order decreases as the phosphite content increases. NMR spectroscopic results confirm the incorporation of oxo-phosphorus entities to the framework of these materials and also provide us useful information concerning the mechanism through which they are formed.

El Haskouri, Jamal; Pérez-Cabero, Mónica; Guillem, Carmen; Latorre, Julio; Beltrán, Aurelio; Beltrán, Daniel; Amorós, Pedro

2009-08-01

338

Breakthrough and future: nanoscale controls of compositions, morphologies, and mesochannel orientations toward advanced mesoporous materials.  

PubMed

Currently, ordered mesoporous materials prepared through the self-assembly of surfactants have attracted growing interests owing to their special properties, including uniform mesopores and a high specific surface area. Here we focus on fine controls of compositions, morphologies, mesochannel orientations which are important factors for design of mesoporous materials with new functionalities. This Review describes our recent progress toward advanced mesoporous materials. Mesoporous materials now include a variety of inorganic-based materials, for example, transition-metal oxides, carbons, inorganic-organic hybrid materials, polymers, and even metals. Mesoporous metals with metallic frameworks can be produced by using surfactant-based synthesis with electrochemical methods. Owing to their metallic frameworks, mesoporous metals with high electroconductivity and high surface areas hold promise for a wide range of potential applications, such as electronic devices, magnetic recording media, and metal catalysts. Fabrication of mesoporous materials with controllable morphologies is also one of the main subjects in this rapidly developing research field. Mesoporous materials in the form of films, spheres, fibers, and tubes have been obtained by various synthetic processes such as evaporation-mediated direct templating (EDIT), spray-dried techniques, and collaboration with hard-templates such as porous anodic alumina and polymer membranes. Furthermore, we have developed several approaches for orientation controls of 1D mesochannels. The macroscopic-scale controls of mesochannels are important for innovative applications such as molecular-scale devices and electrodes with enhanced diffusions of guest species. PMID:20069589

Yamauchi, Yusuke; Suzuki, Norihiro; Radhakrishnan, Logudurai; Wang, Liang

2009-01-01

339

Potential of activated carbon from waste rubber tire for the adsorption of phenolics: effect of pre-treatment conditions.  

PubMed

Rubber tire activated carbon modification (RTACMC) and rubber tire activated carbon (RTAC) were prepared from waste rubber tire by microwave assisted chemical treatment and physical heating respectively. A greater improvement in porosity and total pore volume was achieved in RTACMC as compared to that of RTAC. But both have a predominantly mesoporous structure. Under identical operating conditions, an irradiation time of 10 min, chemical impregnation ratio of 1.50 and a microwave power of 600 W resulted in maximizing the efficiency of RTACMC for p-cresol (250 mg/g) at a contact time of 90 min while RTAC showed a 71.43 mg/g adsorption capacity at 150 min. Phenol, due to its higher solubility was adsorbed to a lesser extent by both adsorbents. Physical nature of interactions, pore diffusion mechanism and exothermicity of the adsorption process was operative in both adsorbents. The outcomes support the feasibility of preparing high quality activated carbon from waste rubber tire by microwave assisted chemical activation. PMID:24407705

Gupta, Vinod Kumar; Nayak, Arunima; Agarwal, Shilpi; Tyagi, Inderjeet

2014-03-01

340

Study of activated carbon modified with sodium carbonate as a possible antacid drug  

Microsoft Academic Search

Activated carbon was modified with different sodium carbonate solutions (0.5 to 3.0 M) to produce a series of possible antacids. The modified carbon was characterized by means of XRD and BET surface area measurements. XRD confirmed the presence of bicarbonate species on the surface of the modified carbons, while the surface areas indicated that microporous of the solids were partially

Carlos F. Linares; Alexia Palencia; Mireya R. Goldwasser; Karina Rodríguez

2006-01-01

341

Mesoporous aluminum phosphite  

SciTech Connect

High surface area pure mesoporous aluminum-phosphorus oxide-based derivatives have been synthesized through an S{sup +}I{sup -} surfactant-assisted cooperative mechanism by means of a one-pot preparative procedure from aqueous solution and starting from aluminum atrane complexes and phosphoric and/or phosphorous acids. A soft chemical extraction procedure allows opening the pore system of the parent as-prepared materials by exchanging the surfactant without mesostructure collapse. The nature of the pore wall can be modulated from mesoporous aluminum phosphate (ALPO) up to total incorporation of phosphite entities (mesoporous aluminum phosphite), which results in a gradual evolution of the acidic properties of the final materials. While phosphate groups in ALPO act as network building blocks (bridging Al atoms), the phosphite entities become basically attached to the pore surface, what gives practically empty channels. The mesoporous nature of the final materials is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N{sub 2} adsorption-desorption isotherms. The materials present regular unimodal pore systems whose order decreases as the phosphite content increases. NMR spectroscopic results confirm the incorporation of oxo-phosphorus entities to the framework of these materials and also provide us useful information concerning the mechanism through which they are formed. - Abstract: TEM image of the mesoporous aluminum phosphite showing the hexagonal disordered pore array that is generated by using surfactant micelles as template. Also a scheme emphasizing the presence of an alumina-rich core and an ALPO-like pore surface is presented.

El Haskouri, Jamal, E-mail: haskouri@uv.e [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain); Perez-Cabero, Monica; Guillem, Carmen; Latorre, Julio; Beltran, Aurelio; Beltran, Daniel [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain); Amoros, Pedro, E-mail: pedro.amoros@uv.e [Institut de Ciencia dels Materials de la Universitat de Valencia (ICMUV), P. O. Box 22085, 46071 Valencia (Spain)

2009-08-15

342

Adsorbed natural gas storage with activated carbon  

SciTech Connect

Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

Sun, Jian; Brady, T.A.; Rood, M.J. [Univ. of Illinois, Urbana, IL (United States)] [and others

1996-12-31

343

Mesoporous silica as a membrane for ultra-thin implantable direct glucose fuel cells.  

PubMed

The design, fabrication and characterization of an inorganic catalyst based direct glucose fuel cell using mesoporous silica coating as a functional membrane is reported. The desired use of mesoporous silica based direct glucose fuel cell is for a blood vessel implantable device. Blood vessel implantable direct glucose fuel cells have access to higher continuous glucose concentrations. However, reduction in the implant thickness is required for application in the venous system as part of a stent. We report development of an implantable device with a platinum thin-film (thickness: 25 nm) deposited on silicon substrate (500 ?m) to serve as the anode, and graphene pressed on a stainless steel mesh (175 ?m) to serve as the cathode. Control experiments involved the use of a surfactant-coated polypropylene membrane (50 ?m) with activated carbon (198 ?m) electrodes. We demonstrate that a mesoporous silica thin film (270 nm) is capable of replacing the conventional polymer based membranes with an improvement in the power generated over conventional direct glucose fuel cells. PMID:21637881

Sharma, Tushar; Hu, Ye; Stoller, Meryl; Feldman, Marc; Ruoff, Rodney S; Ferrari, Mauro; Zhang, Xiaojing

2011-07-21

344

Ni and Rh containing mesoporous amorphous silicate catalysts for dry reforming of methane  

NASA Astrophysics Data System (ADS)

TUD-1 mesoporous silicate materials with incorporated Ni and Rh were prepared by sol-gel one-pot synthesis. The catalytic performance of synthesized materials in dry reforming of methane was compared as well as the stability in time-on-stream experiments. These materials with directly incorporated active metals allowed remarkable increasing of CH4 and CO2 conversions up to 92 % and 95 %, respectively. Ni-TUD-1 catalyst provided very low carbon deposition together with the excellent stability over 50 h. The effect of Rh addition was evaluated.

Parkhomenko, K.; Tyunyaev, A.; Martinez Tejada, L. M.; Dedov, A.; Loktev, A.; Moiseev, I.; Roger, A.-C.

2011-03-01

345

Efficient visible-light photocatalytic activity by band alignment in mesoporous ternary polyoxometalate-Ag2S-CdS semiconductors  

NASA Astrophysics Data System (ADS)

Porous multicomponent semiconductor materials show improved photocatalytic performance due to the large and accessible pore surface area and high charge separation efficiency. Here we report the synthesis of well-ordered porous polyoxometalate (POM)-Ag2S-CdS hybrid mesostructures featuring a controllable composition and high photocatalytic activity via a two-step hard-templating and topotactic ion-exchange chemical process. Ag2S compounds and polyoxometalate cluster anions with different reduction potentials, such as PW12O403-, SiW12O404- and PMo12O403-, were employed as electron acceptors in these ternary heterojunction photocatalysts. Characterization by small-angle X-ray scattering, X-ray diffraction, transmission electron microscopy and N2 physisorption measurements showed hexagonal arrays of POM-Ag2S-CdS hybrid nanorods with large internal BET surface areas and uniform mesopores. The Keggin structure of the incorporated POM clusters was also verified by elemental X-ray spectroscopy microanalysis, infrared and diffuse-reflectance ultraviolet-visible spectroscopy. These new porous materials were implemented as visible-light-driven photocatalysts, displaying exceptional high activity in aerobic oxidation of various para-substituted benzyl alcohols to the corresponding carbonyl compounds. Our experiments show that the spatial separation of photogenerated electrons and holes at CdS through the potential gradient along the CdS-Ag2S-POM interfaces is responsible for the increased photocatalytic activity.Porous multicomponent semiconductor materials show improved photocatalytic performance due to the large and accessible pore surface area and high charge separation efficiency. Here we report the synthesis of well-ordered porous polyoxometalate (POM)-Ag2S-CdS hybrid mesostructures featuring a controllable composition and high photocatalytic activity via a two-step hard-templating and topotactic ion-exchange chemical process. Ag2S compounds and polyoxometalate cluster anions with different reduction potentials, such as PW12O403-, SiW12O404- and PMo12O403-, were employed as electron acceptors in these ternary heterojunction photocatalysts. Characterization by small-angle X-ray scattering, X-ray diffraction, transmission electron microscopy and N2 physisorption measurements showed hexagonal arrays of POM-Ag2S-CdS hybrid nanorods with large internal BET surface areas and uniform mesopores. The Keggin structure of the incorporated POM clusters was also verified by elemental X-ray spectroscopy microanalysis, infrared and diffuse-reflectance ultraviolet-visible spectroscopy. These new porous materials were implemented as visible-light-driven photocatalysts, displaying exceptional high activity in aerobic oxidation of various para-substituted benzyl alcohols to the corresponding carbonyl compounds. Our experiments show that the spatial separation of photogenerated electrons and holes at CdS through the potential gradient along the CdS-Ag2S-POM interfaces is responsible for the increased photocatalytic activity. Electronic supplementary information (ESI) available: EDS spectra of STA/CdS and STA/Ag2S/CdS samples, SAXS patterns and N2 physisorption isotherms of SBA-15 silica, IR spectra of meso-CdS and POM-Ag2S-CdS materials, catalytic data of the as-prepared CdS based mesostructures and TiO2 (Degussa P25) nanoparticles, PL spectra of meso-CdS, Ag2S-CdS, CuS/CdS and STA/Ag2S/CdS samples, N2 physisorption isotherms of b-STA/Ag2S/CdS and STA/CuS/CdS, 1H NMR spectra of 8 oxidation products, and EDS and IR spectra and N2 physisorption isotherms of the reused STA/Ag2S/CdS catalyst. See DOI: 10.1039/c4nr01094a

Kornarakis, I.; Lykakis, I. N.; Vordos, N.; Armatas, G. S.

2014-07-01

346

CHROMIUM REMOVAL BY ACTIVATED CARBON PREPARED FROM COCONUT SHELL  

Microsoft Academic Search

One of the main fields of activated carbons employment is pollution control. The features ofactivated carbons features such as high adsorption capacity and low cost justify their use in the removal of different pollutant agents such as heavy metals. Chromium is one of the main pollutants and the comprehension of its uptake mechanism in the activated carbon is an important

R. M. Schneider

347

ENTRAINED-FLOW ADSORPTION OF MERCURY USING ACTIVATED CARBON  

EPA Science Inventory

Bench-scale experiments were conducted in a flow reactor to simulate entrained-flow capture of elemental mercury (Hg) by activated carbon. Adsorption of Hg by several commercial activated carbons was examined at different carbon-to-mercury (C:Hg) ratios (by weight) (600:1 - 29000...

348

The regeneration of polluted activated carbon by radiation techniques  

NASA Astrophysics Data System (ADS)

In this paper, the regeneration of used activated carbon from monosodium glutamate factory was experimented using radiation and acid-alkali chemical cleaning method. Results showed that the activated carbon saturated with pollutants can be wash away easily by flushing with chemical solution prior irradiation. DSC was used to monitor the change of carbon adsorption

Minghong, Wu; Borong, Bao; Ruimin, Zhou; Jinliang, Zhu; Longxin, Hu

1998-10-01

349

Gyroidal mesoporous multifunctional nanocomposites via atomic layer deposition.  

PubMed

We demonstrate the preparation of rationally designed, multifunctional, monolithic and periodically ordered mesoporous core-shell nanocomposites with tunable structural characteristics. Three-dimensionally (3D) co-continuous gyroidal mesoporous polymer monoliths are fabricated from a solution-based triblock terpolymer-resol co-assembly and used as the functional templates for the fabrication of free-standing core-shell carbon-titania composites using atomic layer deposition (ALD). The deposition depth into the torturous gyroidal nanonetwork is investigated as a function of ALD conditions and the resulting composites are submitted to different thermal treatments. Results suggest that ALD can homogenously coat mesoporous templates with well defined pore sizes below 50 nm and thicknesses above 10 ?m. Structural tunability like titania shell thickness and pore size control is demonstrated. The ordered nanocomposites exhibit triple functionality; a 3D continuous conductive carbon core that is coated with a crystalline titania shell that in turn is in contact with a 3D continuous mesopore network in a compact monolithic architecture. This materials design is of interest for applications including energy conversion and storage. Gyroidal mesoporous titania monoliths can be obtained through simultaneous titania crystallization and template removal in air. PMID:24950610

Werner, Jörg G; Scherer, Maik R J; Steiner, Ullrich; Wiesner, Ulrich

2014-08-01

350

Preparation and characterization of activated carbon foam from phenolic resin.  

PubMed

Activated carbon foam was successfully prepared from phenolic resin synthesized with phenol and formaldehyde under alkali condition. The influence of process variables, such as steam rate, carbonization temperature, carbonization time, activation temperature and activation time on the adsorption capacities of the activated carbon foam was studied. Under the optimum experimental conditions, the activated carbon foam with a specific surface area 727.62 m(2)/g was obtained. Moreover, the iodine value and carbon tetrachloride value of the activated carbon foam was 1050.28 mg/g and 401.37 mg/g, respectively. The pore size of the activated carbon foam was in the range of 3.5-5 nm which was determined through the N2 adsorption test. In addition, the yield of the activated carbon foam was 36.24%. The result of scanning electron microscopy (SEM) showed that the activated carbon foam became honeycomb structure, and its pore wall was thinner and smoother compared to the unactivated carbon foam. PMID:25084407

Zhao, Xuefei; Lai, Shiquan; Liu, Hongzha; Gao, Lijuan

2009-01-01

351

REPEATED REDUCTIVE AND OXIDATIVE TREATMENTS ON GRANULAR ACTIVATED CARBON  

EPA Science Inventory

Fenton oxidation and Fenton oxidation preceded by reduction solutions were applied to granular activated carbon (GAC) to chemically regenerate the adsorbent. No adsorbate was present on the GAC so physicochemical effects from chemically aggressive regeneration of the carbon coul...

352

Activated carbons from steam exploded wood  

SciTech Connect

In a continuing experimental program, we are investigating the conversion of hardwoods, such as white oak (Quercus alba) to activated carbons by chemical activation with phosphoric acid. The aims of the research are to establish the relationships between chemical and morphological change and porosity development, with the long term goal of developing new adsorbents with controlled porosity and surface chemistry, through the selection of the precursor, reagent, and reaction parameters. The research is further directed to enhancing the use of wood materials, some of which are not appropriate feedstocks for conventional industrial applications, and to providing potential solutions to the problem of the economic utilization of wood wastes from primary and secondary wood industries.

Jagtoyen, M.; Derbyshire, F. [Univ. of Kentucky, Lexington, KY (United States); Wright, R.S.; Glasser, W. [Virginia Polytechnical Institute, Blacksburg, VA (United States)

1995-12-31

353

Synthesis of mesoporous nano-TiO 2 doped with Sn by auto-assembly method and photo-catalytic property  

Microsoft Academic Search

A series of mesoporous nano-TiO2 material doped with Sn are synthesized by a homogenous precipitation method aided by microwave heating, using TiCl4 and SnClm4 as raw materials, urea as precipitator, active carbon as templet, and soluble starch as anti- agglomerating reagent. XRD\\u000a results show that the precursor exists in the amorphous phase, and transforms to anatase structure above 400°C. TEM

Meihong Zhang; Shiwen Ding; Zhenxing Wang; Yuzhuo Zhang

2005-01-01

354

Self-templating synthesis of hollow mesoporous silica and their applications in catalysis and drug delivery.  

PubMed

Hollow mesoporous silica materials have been intensively pursued because of their unique properties for various applications. Yolk/shell structured hollow mesoporous silica with functional cores inside their hollow interior can further broaden the applications of hollow mesoporous silica. The self-templating strategy has been developed as one of the most important strategies to effectively fabricate hollow mesoporous silicas and their yolk/shell counterparts. In this feature article, we provide an overview of advances in the self-templating synthesis of hollow mesoporous silica based on the following three strategies: surface-protected etching, structural difference-based selective etching, and cationic surfactant assisted self-templating. We then discuss some important applications of these self-templating strategy-derived hollow mesoporous silicas, such as nanoreactors for confined catalysis and multifunctional platforms for combined therapy. Finally, some perspectives for the future development of this active research field are provided. PMID:23400270

Fang, Xiaoliang; Zhao, Xiaojing; Fang, Weijun; Chen, Cheng; Zheng, Nanfeng

2013-03-21

355

Mesoporous yolk-shell SnS2-TiO2 visible photocatalysts with enhanced activity and durability in Cr(vi) reduction  

NASA Astrophysics Data System (ADS)

A novel mesoporous yolk-shell SnS2-TiO2 visible photocatalyst (ST-is) was synthesized by in situ doping TiO2 with SnO2 through solvothermal alcoholysis, followed by sulfurization under hydrothermal conditions. The ST-is displayed higher activity in photocatalytic reduction of Cr(vi) owing to the strong photosensitizing effect of SnS2 in uniform nanoparticles and the enhanced light harvesting via multiple reflections in yolk-shell chambers. Meanwhile, the strong SnS2-TiO2 interaction could generate more heterojunctions which facilitated photoelectron transfer from SnS2 to TiO2, leading to the enhanced activity by inhibiting photoelectron-hole recombination. Moreover, the ST-is displayed strong durability owing to the strong SnS2-TiO2 interaction and the encapsulation of SnS2 nanoparticles in the yolk-shell chamber, which could inhibit SnS2 leaching. Furthermore, because of the electronegative surface and high surface area, the ST-is could thoroughly purify wastewater by completely adsorbing Cr3+ resulting from Cr(vi) reduction. In addition, the presence of photocatalytic degradation of organic compounds promoted Cr(vi) reduction owing to inhibition of photoelectron-hole recombination by consuming holes.A novel mesoporous yolk-shell SnS2-TiO2 visible photocatalyst (ST-is) was synthesized by in situ doping TiO2 with SnO2 through solvothermal alcoholysis, followed by sulfurization under hydrothermal conditions. The ST-is displayed higher activity in photocatalytic reduction of Cr(vi) owing to the strong photosensitizing effect of SnS2 in uniform nanoparticles and the enhanced light harvesting via multiple reflections in yolk-shell chambers. Meanwhile, the strong SnS2-TiO2 interaction could generate more heterojunctions which facilitated photoelectron transfer from SnS2 to TiO2, leading to the enhanced activity by inhibiting photoelectron-hole recombination. Moreover, the ST-is displayed strong durability owing to the strong SnS2-TiO2 interaction and the encapsulation of SnS2 nanoparticles in the yolk-shell chamber, which could inhibit SnS2 leaching. Furthermore, because of the electronegative surface and high surface area, the ST-is could thoroughly purify wastewater by completely adsorbing Cr3+ resulting from Cr(vi) reduction. In addition, the presence of photocatalytic degradation of organic compounds promoted Cr(vi) reduction owing to inhibition of photoelectron-hole recombination by consuming holes. Electronic supplementary information (ESI) available: Details of the FESEM images, TEM images, N2 adsorption-desorption isotherms, FTIR spectra, XRD patterns, XPS spectra, zeta-potential test, Mott-Schottky plots, and the schematic illustration of the charge separation in SnS2-TiO2 photocatalysts under visible light irradiation. See DOI: 10.1039/c2nr33755j

Wang, Jinguo; Li, Xinru; Li, Xi; Zhu, Jian; Li, Hexing

2013-02-01

356

REACTIONS OF CHLORITE WITH ACTIVATED CARBON AND WITH VANILLIC ACID AND INDAN ADSORBED ON ACTIVATED CARBON  

EPA Science Inventory

The reaction between chlorite (CO2(-1)) and vanillic acid, at pH 6.0 in the presence of granular activated carbon (GAC), yielded several reaction products identifiable by GC/MS; no products were found in the absence of GAC. Indan and ClO2 or ClO2(-1) reacted in aqueous solution a...

357

Core-shell structured silicon nanoparticles@TiO2-x/carbon mesoporous microfiber composite as a safe and high-performance lithium-ion battery anode.  

PubMed

A core-shell structured Si nanoparticles@TiO2-x/C mesoporous microfiber composite has been synthesized by an electrospinning method. The core-shell composite exhibits high reversible capacity, excellent rate capability, and improved cycle performance as an anode material for Li-ion batteries. Furthermore, it shows remarkable suppression of exothermic behavior, which can prevent possible thermal runaway and safety problems of the cells. The improved electrochemical and thermal properties are ascribed to the mechanically, electrically, and thermally robust shell structure of the TiO2-x/C nanocomposite encapsulating the Si nanoparticles, which is suggested as a promising material architecture for a safe and reliable Si-based Li-ion battery of high energy density. PMID:24552160

Jeong, Goojin; Kim, Jae-Geun; Park, Min-Sik; Seo, Minsu; Hwang, Soo Min; Kim, Young-Ugk; Kim, Young-Jun; Kim, Jung Ho; Dou, Shi Xue

2014-03-25

358

DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS  

SciTech Connect

The increasing role of coal as a source of energy in the 21st century will demand environmental and cost-effective strategies for the use of coal combustion by-products (CCBPs), mainly unburned carbon in fly ash. Unburned carbon is nowadays regarded as a waste product and its fate is mainly disposal, due to the present lack of efficient routes for its utilization. However, unburned carbon is a potential precursor for the production of adsorbent carbons, since it has gone through a devolatilization process while in the combustor, and therefore, only requires to be activated. Accordingly, the principal objective of this work was to characterize and utilize the unburned carbon in fly ash for the production of activated carbons. The unburned carbon samples were collected from different combustion systems, including pulverized utility boilers, a utility cyclone, a stoker, and a fluidized bed combustor. LOI (loss-on-ignition), proximate, ultimate, and petrographic analyses were conducted, and the surface areas of the samples were characterized by N2 adsorption isotherms at 77K. The LOIs of the unburned carbon samples varied between 21.79-84.52%. The proximate analyses showed that all the samples had very low moisture contents (0.17 to 3.39 wt %), while the volatile matter contents varied between 0.45 to 24.82 wt%. The elemental analyses show that all the unburned carbon samples consist mainly of carbon with very little hydrogen, nitrogen, sulfur and oxygen In addition, the potential use of unburned carbon as precursor for activated carbon (AC) was investigated. Activated carbons with specific surface area up to 1075m{sup 2}/g were produced from the unburned carbon. The porosity of the resultant activated carbons was related to the properties of the unburned carbon feedstock and the activation conditions used. It was found that not all the unburned carbon samples are equally suited for activation, and furthermore, their potential as activated carbons precursors could be inferred from their physical and chemical properties. The developed porosity of the activated carbon was a function of the oxygen content, porosity and H/C ratio of the parent unburned carbon feedstock. It was observed that extended activation times and high activation temperatures increased the porosity of the produced activated carbon at the expense of the solid yield. The development of activated carbon from unburned carbon in fly ash has been proven to be a success by this study in terms of the higher surface areas of the resultant activated carbons, which are comparable with commercial activated carbons. However, unburned carbon samples obtained from coal-fired power plants as by-product have high ash content, which is unwanted for the production of activated carbons. Therefore, the separation of unburned carbon from the fly ash is expected to be beneficial for the utilization of unburned carbon to produce activated carbons with low ash content.

Harold H. Schobert; M. Mercedes Maroto-Valer; Zhe Lu

2003-09-30

359

Carbon-decorated Li4Ti5O12/rutile TiO2 mesoporous microspheres with nanostructures as high-performance anode materials in lithium-ion batteries  

NASA Astrophysics Data System (ADS)

Li4Ti5O12/rutile TiO2 (LTO-RT) composites with Li/Ti molar ratios of 3:5, 4:5 and 4.5:5 have been successfully synthesized with TiO2 microspheres as a precursor. Furthermore, C-coated LTO-RT mesoporous microspheres with a molar ratio of 4:5 (C/4-5-LTO-RT) have been prepared based on the LTO-RT composite through a hydrothermal method and high temperature calcination. After various characterizations, it is found that carbon plays a pivotal role in retaining the porous nanostructure of the original as-prepared TiO2 precursor in the overall process. Substantially, C/4-5-LTO-RT still shows a high specific surface area of 63.70 m2 g-1 even after high temperature treatment at 800 °C. Since the porous nanostructure offers open and direct channels for the diffusion of Li ions and electrons and carbon decoration also efficiently improves the electrical conductivity, the sample of C/4-5-LTO-RT shows an enhanced electrochemical performance. In addition, the presence of nanosized rutile TiO2 in C/4-5-LTO-RT has an important contribution to the high electrochemical performance, as does the fast lithium ion diffusion along the [001] direction.

Gao, Lin; Liu, Rujun; Hu, Hao; Li, Guojian; Yu, Ying

2014-05-01

360

Adsorption of Carbon Dioxide onto Activated Carbon and Nitrogen-Enriched Activated Carbon: Surface Changes, Equilibrium, and Modeling of Fixed-Bed Adsorption  

Microsoft Academic Search

It has been reported that the CO2 adsorption capacity of the N-enriched activated carbon can increase or decrease. In this study a commercial activated carbon was functionalized with 3-chloropropylamine hydrochloride and its adsorption characteristics in a fixed-bed column were investigated. The N-enriched activated carbon presented lower BET surface area than the original activated carbon suggesting that the nitrogen incorporation partially

Tirzhá L. P. Dantas; Suélen M. Amorim; Francisco Murilo T. Luna; Ivanildo J. Silva Jr; Diana C. S. de Azevedo; Alírio E. Rodrigues; Regina F. P. M. Moreira

2009-01-01

361

Superhydrophobic activated carbon-coated sponges for separation and absorption.  

PubMed

Highly porous activated carbon with a large surface area and pore volume was synthesized by KOH activation using commercially available activated carbon as a precursor. By modification with polydimethylsiloxane (PDMS), highly porous activated carbon showed superhydrophobicity with a water contact angle of 163.6°. The changes in wettability of PDMS- treated highly porous activated carbon were attributed to the deposition of a low-surface-energy silicon coating onto activated carbon (confirmed by X-ray photoelectron spectroscopy), which had microporous characteristics (confirmed by XRD, SEM, and TEM analyses). Using an easy dip-coating method, superhydrophobic activated carbon-coated sponges were also fabricated; those exhibited excellent absorption selectivity for the removal of a wide range of organics and oils from water, and also recyclability, thus showing great potential as efficient absorbents for the large-scale removal of organic contaminants or oil spills from water. PMID:23650204

Sun, Hanxue; Li, An; Zhu, Zhaoqi; Liang, Weidong; Zhao, Xinhong; La, Peiqing; Deng, Weiqiao

2013-06-01

362

Role of activated carbon pellets in carbon dioxide removal  

Microsoft Academic Search

The removal of carbon dioxide from gas\\/air streams is more often becoming necessary in many industries for different purposes. In cryogenic air separation plant, air has to be free from carbon dioxide before its liquefaction otherwise blockage due to freezing of heat exchange equipment would result. Enrichment of methane in biogas to have fuel of higher calorific value can be

S. C Sarkar; A Bose

1997-01-01

363

The preparation of active carbons from coal by chemical and physical activation  

Microsoft Academic Search

A series of activated carbons was prepared from bituminous coal by chemical activation with potassium hydroxide and zinc chloride and also by physical activation with carbon dioxide. The effect of process variables such as carbonization time, temperature, particle size, chemical agents, method of mixing and impregnation ratio in the chemical activation process was studied in order to optimize those preparation

A. Ahmadpour; D. D. Do

1996-01-01

364

Characterization of activated carbons from oil-palm shell by CO2 activation with no holding carbonization temperature.  

PubMed

Activated carbons can be produced from different precursors, including coals of different ranks, and lignocellulosic materials, by physical or chemical activation processes. The objective of this paper is to characterize oil-palm shells, as a biomass byproduct from palm-oil mills which were converted into activated carbons by nitrogen pyrolysis followed by CO2 activation. The effects of no holding peak pyrolysis temperature on the physical characteristics of the activated carbons are studied. The BET surface area of the activated carbon is investigated using N2 adsorption at 77 K with selected temperatures of 500, 600, and 700°C. These pyrolysis conditions for preparing the activated carbons are found to yield higher BET surface area at a pyrolysis temperature of 700°C compared to selected commercial activated carbon. The activated carbons thus result in well-developed porosities and predominantly microporosities. By using this activation method, significant improvement can be obtained in the surface characteristics of the activated carbons. Thus this study shows that the preparation time can be shortened while better results of activated carbon can be produced. PMID:23737721

Herawan, S G; Hadi, M S; Ayob, Md R; Putra, A

2013-01-01

365

CYANIDE REMOVAL FROM REFINERY WASTEWATER USING POWDERED ACTIVATED CARBON  

EPA Science Inventory

The objective of this project was to evaluate the removal of low level cyanide in petroleum refinery wastewater by the addition of powdered activated carbon and cupric chloride to an activated sludge unit. The activated carbon and cupric chloride act as a catalyst in the oxidatio...

366

Colonization of Biological Activated Carbon in Drinking Water Purification  

Microsoft Academic Search

The colonization of columnar activated carbon was developed. Some analysis of several physical–chemical, biochemical and microbiological methods (indicators) used to characterize the BAC biofilm's composition and activity was provided. The filtration column filled with columnar activated carbon was operated incessantly for 72 days in the condition of natural colonization in a dynamic flow and poor nutritional status. The mature biofilm

He Wang; Zhonglin Chen; Jimin Shen; Feifei Xiang; Yu Liu; Xu Zhai; Yue Liu

2010-01-01

367

Adsorption of basic dyes from aqueous solution onto activated carbons  

Microsoft Academic Search

The aim of this research is to compare the adsorption capacity of different types of activated carbons produced by steam activation in small laboratory scale and large industrial scale processes. Equilibrium behaviour of the activated carbons was investigated by performing batch adsorption experiments using bottle-point method. Basic dyes (methylene blue (MB), basic red (BR) and basic yellow (BY)) were used

Emad N. El Qada; Stephen J. Allen; Gavin M. Walker

2008-01-01

368

Competitive Carbon-Sulfur vs Carbon-Carbon Bond Activation of 2-Cyanothiophene with [Ni(dippe)H]2  

E-print Network

Competitive Carbon-Sulfur vs Carbon-Carbon Bond Activation of 2-Cyanothiophene with [Ni(dippe)H]2 Hydrodesulfurization (HDS) is the process by which sulfur is removed from hydrocarbons during the refinement of petroleum. Failure to remove sulfur during this process results in the formation of noxious sulfur oxides

Jones, William D.

369

Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles  

E-print Network

Enhanced Cellular Activation with Single Walled Carbon Nanotube Bundles Presenting Antibody Stimuli the body using single walled carbon nanotube (SWNT) bundles presenting antibody stimuli. Owing to the large of lymphocytes, useful for basic science applications and clinical immunotherapy. Single walled carbon nanotubes

Fahmy, Tarek

370

Activated carbon from pecan shell: process description and economic analysis  

Microsoft Academic Search

Granular activated carbons derived from pecan shells have been shown to adsorb a variety of metal and organic species in various processing wastewaters. Their effectiveness is equivalent to or exceeds comparable commercial carbons in this regard. The objectives of this study were to develop process flow diagrams for the large-scale production of pecan shell-based carbons derived from steam or phosphoric

Chilton Ng; Wayne E Marshall; Ramu M Rao; Rishipal R Bansode; Jacques N Losso

2003-01-01

371

Activated carbon–carbon nanotube composite porous film for supercapacitor applications  

Microsoft Academic Search

Activated carbon\\/carbon nanotube composite electrodes have been assembled and tested in organic electrolyte (NEt4BF4 1.5M in acetonitrile). The performances of such cells have been compared with pure activated carbon-based electrodes. CNTs content of 15wt.% seems to be a good compromise between power and energy, with a cell series resistance of 0.6?cm2 and an active material capacitance as high as 88Fg?1.

Pierre-Louis Taberna; Geoffroy Chevallier; Patrice Simon; Dominique Plée; Thierry Aubert

2006-01-01

372

Sorption of dichlorodiphenyltrichloroethane (DDT) and its metabolites by activated carbon in clean water and sediment slurries.  

PubMed

Polyethylene-water partitioning coefficients (K(PE)) and mass transfer coefficients (k(PE)) for the ortho and para isomers of the organochlorine pesticide dichlorodiphenyltrichloroethane (DDT) and its metabolites dichlorodiphenyldichloroethane (DDD), dichlorodiphenyldichloroethylene (DDE) and, dichlorodiphenylmonochloroethylene (DDMU) were measured. These data were used to derive activated carbon (AC) sorption isotherms in clean water in the sub-nanogram per litre free aqueous concentration range for a virgin and a regenerated AC. The sorption strength of AC for DDT and its metabolites was very high and logarithmic values of the AC-water partitioning coefficients, logK(AC), ranged from 8.47 to 9.26. A numerical mass transfer model was calibrated with this data to interpret previously reported reductions in DDT uptake by semipermeable membrane devices after AC amendment of sediment from Lauritzen Channel, California, USA. The activated carbon-water partitioning coefficient values (K(AC)) measured in clean water systems appear to overestimate the AC sorption capacity in sediment up to a factor 32 for DDT and its metabolites at long contact time with fine-sized AC. Modelling results show decreased attenuation of the AC sorption capacity with increased sediment-AC contact time. We infer that increased resistance in mass transfer of DDTs to sorption sites in the microporous region likely caused by deposits of dissolved organic matter in the macro- and mesopores of AC appears to be the most relevant fouling mechanism. These results suggest that DDTs may diffuse through possible deposits of dissolved organic matter over time, implying that the effects of sediment on the sorption of DDTs by AC may be more kinetic than competitive. PMID:19595428

Hale, Sarah E; Tomaszewski, Jeanne E; Luthy, Richard G; Werner, David

2009-09-01

373

Active carbon filter health condition detection with piezoelectric wafer active sensors  

Microsoft Academic Search

The impregnated active carbon used in air purification systems degrades over time due to exposure to contamination and mechanical effects (packing, settling, flow channeling, etc.). A novel approach is proposed to detect contamination in active carbon filters by combining the electromechanical impedance spectroscopy (EMIS) and electrochemical impedance spectroscopy (ECIS). ECIS is currently being used to evaluate active carbon filtration material;

Jingjing Bao; Victor Giurgiutiu; Glenn O. Rubel; Gregory W. Peterson; Thomas M. Ball

2011-01-01

374

JPL Activated Carbon Treatment System (ACTS) for sewage  

NASA Technical Reports Server (NTRS)

An Activated Carbon Treatment System (ACTS) was developed for sewage treatment and is being applied to a one-million gallon per day sewage treatment pilot plant in Orange County California. Activities reported include pyrolysis and activation of carbon-sewage sludge, and activated carbon treatment of sewage to meet ocean discharge standards. The ACTS Sewage treatment operations include carbon-sewage treatment, primary and secondary clarifiers, gravity (multi-media) filter, filter press dewatering, flash drying of carbon-sewage filter cake, and sludge pyrolysis and activation. Tests were conducted on a laboratory scale, 10,000 gallon per day demonstration plant and pilot test equipment. Preliminary economic studies are favorable to the ACTS process relative to activated sludge treatment for a 175,000,000 gallon per day sewage treatment plant.

1976-01-01

375

Sensitive ECL immunosensor for detection of retinol-binding protein based on double-assisted signal amplification strategy of multiwalled carbon nanotubes and Ru(bpy)3(2+) doped mesoporous silica nanospheres.  

PubMed

A novel electrochemiluminescence (ECL) strategy based on the sandwich-type immunosensor for sensitive detection of retinol-binding protein (RBP) was developed. The primary antibody anti-RBP was immobilized onto multiwalled carbon nanotubes (MWCNTs), which have large surface area and high electrical conductivity. The RBP antigen and Ru-Nafion@SiO2-labeled secondary antibody were then successively conjugated to form sandwich-type immunocomplexes through the specific interaction between antigen and antibody. The ECL signal amplification was significantly improved due to the synergistic effect of MWCNTs and mesoporous silica nanospheres (mSiO2). The developed ECL immunosensor exhibited high sensitivity and specificity for the detection of RBP and responded linearly to the clinically-relevant concentration of RBP from 78 to 5000 ng mL(-1). Moreover, the MWCNT-based ECL immunosensor displayed excellent stability and reproducibility, as well as successfully achieved the detection of RBP in patient urine samples with desirable results. The present work provided a promising technique for the clinical screening of RBP and point-of-care diagnostics. PMID:23876540

Wu, Beina; Hu, Chenyi; Hu, Xiaoqing; Cao, Hongmei; Huang, Chusen; Shen, Hebai; Jia, Nengqin

2013-12-15

376

Synthesis and photocatalytic activity of mesoporous cerium doped TiO{sub 2} as visible light sensitive photocatalyst  

SciTech Connect

Graphical abstract: Cerium doped titania having optimum 5 wt% of cerium can decompose methylene blue and reduce selenium (IV) efficiently under visible light. Highlights: Black-Right-Pointing-Pointer Effect of cerium doping on the surface properties and visible light mediated photocatalytic reaction is studied. Black-Right-Pointing-Pointer Cerium doping increases the anatase phase stability, surface area (up to 137 m{sup 2}/g) and visible light absorption. Black-Right-Pointing-Pointer Importance of Ce{sup 3+}/Ce{sup 4+}, oxygen vacancy, surface area and crystallinity is correlated with improved catalytic activity. Black-Right-Pointing-Pointer Material with 5 wt% Ce is found to be most active photocatalyst for methylene blue decomposition and Se (IV) reduction. -- Abstract: Cerium doped titania materials were synthesized varying the cerium concentration from 0 to 10 wt%. Materials are characterised by XRD, TEM, XPS and N{sub 2} adsorption desorption method. Surface area and visible light absorption substantially increases and crystallite size decreases with the increasing cerium content. Cerium doping stabilizes the anatase phase and surface area even at 600 Degree-Sign C calcination. Photocatalytic activity towards methylene blue decomposition and selenium (IV) reduction is found to increase with the cerium content up to 5 wt% and then decreases. Materials calcined at 600 Degree-Sign C shows better activity than that calcined at 400 Degree-Sign C, even though surface area decreases. Anatase crystallinity mostly decides the photocatalytic activity rather than only surface area. It can be concluded that the optimum visible light absorption and oxygen vacancy with 5% cerium doping enhances the photocatalytic activity. In addition photocatalytic performance is found to depend on the presence of Ce{sup 4+}/Ce{sup 3+} rather than only visible light absorption.

Aman, Noor [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)] [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Satapathy, P.K. [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)] [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India); Mishra, T., E-mail: drtmishra@yahoo.com [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Mahato, M. [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India)] [CSE Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Das, N.N. [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)] [PG Department of Chemistry, North Orissa University, Baripada 757003, Orissa (India)

2012-02-15

377

Supporting Information Unexpected Role of Activated Carbon in Promoting  

E-print Network

-min/L and then air-dried; and (iii) PSC particles were baked at. Activated Carbons, Modifications and Characterization. The suite of activated carbon particles and fibers used in this study included: (i) synthetic Ambersorb 572 particles from Rohm and Haas (Philadelphia, PA

Huang, Ching-Hua

378

Bioindication Potential of Carbonic Anhydrase Activity in Anemones  

E-print Network

Bioindication Potential of Carbonic Anhydrase Activity in Anemones and Corals AUBREY L. GILBERT levels of carbonic anhydrase (CA) were assessed in anemones Condylactis gigantea and Stichodactyla he has been done on CA activity in anemones and corals, two potential candidates for coral reef

Bermingham, Eldredge

379

Metal containing mesoporous silica materials: Synthesis, characterization, and applications  

NASA Astrophysics Data System (ADS)

The work presented here comprises the development of a new route for the incorporation of transition metals (TM = Mn, V, Cr) into the pores of mesoporous silica materials, the characterization, and the applications of the resulting materials. The mesoporous silica material used in this work is of the M41S family, known as MCM-48. The first part of the work is going to be focused on in the incorporation of manganese species. Characterization of the resulting materials will be sub-divided in two major parts: (1) Structural and textural properties and (2) Analysis of the Mn oxidation state, coordination and location in the mesoporous host. The process of incorporation of Mn into the mesoporous materials takes place by using high valence metal precursor anions. Then a mechanism to describe the process of loading the Mn species will be proposed. The method developed makes possible the incorporation of high loadings of transition metals while maintaining the properties of the host material, MCM-48. In the second part of the research the synthesis method developed in the first part is used to incorporate other transition metals such as vanadium and chromium. As in the first part, the nature of the TM species is investigated and their catalytic application in oxidation of styrene is also studied. The materials show good activity towards styrene oxidation with conversions as high as 100%. The catalysts can also be recycled without significant loss of activity. Finally, the last part of the research deals with the incorporation of tin oxide into mesoporous silica. A similar approach to the one used for transition metals was used to load tin in MCM-48, however, discrete tin oxide nanoparticles were formed on the surface of the mesoporous structure rather than inside of the pores. The sensing properties towards reducing gases such as hydrogen of these materials were tested, and the Sn containing mesoporous silica show promising properties for gas sensing applications.

Gomez, Sinue

380

Adsorption and desorption performance of benzene over hierarchically structured carbon–silica aerogel composites  

Microsoft Academic Search

Hierarchically structured carbon–silica aerogel (CSA) composites were synthesized from cheap water glass precursors and granulated activated carbon via a post-synthesis surface modification with trimethylchlorosilane (TMCS) and a low-cost ambient pressure drying procedure. The resultant CSA composites possess micro\\/mesoporous structure and hydrophobic surface. The adsorption and desorption performance of benzene on carbon–silica aerogel composite (CSA-2) under static and dynamic conditions were

Baojuan Dou; Jinjun Li; Yufei Wang; Hailin Wang; Chunyan Ma; Zhengping Hao

2011-01-01

381

Improvement of the visible-light photocatalytic performance of TiO2 by carbon mesostructures.  

PubMed

An improvement in the photodegradation performance for dyes due to interaction between carbon and titania in a self-assembled mesoporous C-TiO(2) composite catalyst, even for the difficult degradation of azo dyes, is reported herein. The dye removal process involves adsorption of the dye from water by the mesoporous carbon-titania, followed by photodegradation on the separated dye-loaded solid. Such adsorption-catalysis cycles can be carried out more than 80 times without discernible loss of photocatalytic activity or the anatase content of the composite. In each run, about 120 mg dye per g catalyst can be degraded. The mesoporous carbon-titania catalyst also exhibits a high capacity for converting methyl orange in aqueous solution under visible light. Characterization by XRD, TEM, and N(2) sorption techniques has revealed that the self-assembled composite catalyst has an ordered mesostructure, uniform mesopores (4.3 nm), a large pore volume (0.30 cm(3) g(-1)), and a high surface area (348 m(2) g(-1)). The pore walls are composed of amorphous carbon and anatase nanoparticles of size 4.2 nm, which are well dispersed and confined. X-ray photoelectron spectroscopy (XPS), surface photovoltage spectroscopy (SPS), and UV/Vis absorption results indicate doping of carbon into the anatase lattice and a change in the bandgap of the semiconductor. The synergistic improvement in the composite catalyst can be attributed to the following features: (1) carbon doping of the anatase lattice modifies its bandgap and enhances its activity under visible light; (2) confinement within carbon pore walls prevents aggregation of tiny anatase nanoparticles, improving their activity and stability; (3) the mesopores provide a confined space for photocatalysis; and (4) the strong adsorption ability of porous carbon for organic substances ensures that large quantities can be processed and inhibits further diffusion of the adsorbed organic substances, thereby enhancing the mineralization on anatase. PMID:23225547

Wei, Wei; Yu, Chao; Zhao, Qingfei; Li, Guisheng; Wan, Ying

2013-01-01

382

Ozone Removal by Filters Containing Activated Carbon: A Pilot Study  

SciTech Connect

This study evaluated the ozone removal performance of moderate-cost particle filters containing activated carbon when installed in a commercial building heating, ventilating, and air conditioning (HVAC) system. Filters containing 300 g of activated carbon per 0.09 m2 of filter face area were installed in two 'experimental' filter banks within an office building located in Sacramento, CA. The ozone removal performance of the filters was assessed through periodic measurements of ozone concentrations in the air upstream and downstream of the filters. Ozone concentrations were also measured upstream and downstream of a 'reference' filter bank containing filters without any activated carbon. The filter banks with prefilters containing activated carbon were removing 60percent to 70percent of the ozone 67 and 81 days after filter installation. In contrast, there was negligible ozone removal by the reference filter bank without activated carbon.

Fisk, William; Spears, Mike; Sullivan, Douglas; Mendell, Mark

2009-09-01

383

Mesoporous materials for antihydrogen production.  

PubMed

Antimatter is barely known by the chemist community and this article has the vocation to explain how antimatter, in particular antihydrogen, can be obtained, as well as to show how mesoporous materials could be used as a further improvement for the production of antimatter at very low temperatures (below 1 K). The first experiments with mesoporous materials highlighted in this review show very promising and exciting results. Mesoporous materials such as mesoporous silicon, mesoporous material films, pellets of MCM-41 and silica aerogel show remarkable features for antihydrogen formation. Yet, the characteristics for the best future mesoporous materials (e.g. pore sizes, pore connectivity, shape, surface chemistry) remain to be clearly identified. For now among the best candidates are pellets of MCM-41 and aerogel with pore sizes between 10 and 30 nm, possessing hydrophobic patches on their surface to avoid ice formation at low temperature. From a fundamental standpoint, antimatter experiments could help to shed light on open issues, such as the apparent asymmetry between matter and antimatter in our universe and the gravitational behaviour of antimatter. To this purpose, basic studies on antimatter are necessary and a convenient production of antimatter is required. It is exactly where mesoporous materials could be very useful. PMID:23250616

Consolati, Giovanni; Ferragut, Rafael; Galarneau, Anne; Di Renzo, Francesco; Quasso, Fiorenza

2013-05-01

384

Thermally stable SiO 2-doped mesoporous anatase TiO 2 with large surface area and excellent photocatalytic activity  

Microsoft Academic Search

A thermally stable SiO2-doped mesoporous TiO2 with high crystallinity was prepared by a templating method. The content of SiO2 dopant was varied from 3% to 20%. The gels were characterized by TG-DTA analysis. And the resultant catalysts were investigated by various physicochemical techniques, such as WAXRD, Raman spectroscopy, N2 adsorption–desorption, TEM, FT-IR, and XPS. The WAXRD, TEM, and Raman measurements

Chenxu He; Baozhu Tian; Jinlong Zhang

2010-01-01

385

Selecting activated carbon for water and wastewater treatability studies  

SciTech Connect

A series of follow-up investigations were performed to produce data for improving the four-indicator carbon selection method that we developed to identify high-potential activated carbons effective for removing specific organic water pollutants. The carbon's pore structure and surface chemistry are dependent on the raw material and the activation process. Coconut carbons have relatively more small pores than large pores; coal and apricot nutshell/walnut shell fruit carbons have the desirable pore structures for removing adsorbates of all sizes. Chemical activation, excessive activation, and/or thermal reactivation enlarge small pores, resulting in reduced phenol number and higher tannic acid number. Activated carbon's phenol, iodine, methylene blue, and tannic acid numbers are convenient indicators of its surface area and pore volume of pore diameters < 10, 10-15, 15-28, and > 28 angstrom, respectively. The phenol number of a carbon is also a good indicator of its surface acidity of oxygen-containing organic functional groups that affect the adsorptive capacity for aromatic and other small polar organics. The tannic acid number is an indicator of carbon's capacity for large, high-molecular-weight natural organic precursors of disinfection by-products in water treatment. The experimental results for removing nitrobenzene, methyl-tert-butyl ether, 4,4-bisphenol, humic acid, and the organic constituents of a biologically treated coking-plant effluent have demonstrated the effectiveness of this capacity-indicator-based method of carbon selection.

Zhang, W.; Chang, Q.G.; Liu, W.D.; Li, B.J.; Jiang, W.X.; Fu, L.J.; Ying, W.C. [East China University of Chemical Technology, Shanghai (China)

2007-10-15

386

Basic dye adsorption on activated carbon  

Microsoft Academic Search

The adsorption of Victoria Blue dye (Basic Blue 26) on carbon has been investigated. Equilibrium data have been found to obey the Langmuir isotherm. The effects of contact time, agitation, initial dye concentration and carbon particle size range were also studied.

Gordon McKay

1979-01-01

387

Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) have shown great promise as high performance materials for adsorbing priority pollutants from water and wastewater. This study compared uptake of two contaminants of interest in drinking water treatment (atrazine and trichloroethylene) by nine different types of carbonaceous adsorbents: three different types of single walled carbon nanotubes (SWNTs), three different sized multi-walled nanotubes (MWNTs), two granular activated carbons (GACs) and a powdered activated carbon (PAC). On a mass basis, the activated carbons exhibited the highest uptake, followed by SWNTs and MWNTs. However, metallic impurities in SWNTs and multiple walls in MWNTs contribute to adsorbent mass but do not contribute commensurate adsorption sites. Therefore, when uptake was normalized by purity (carbon content) and surface area (instead of mass), the isotherms collapsed and much of the CNT data was comparable to the activated carbons, indicating that these two characteristics drive much of the observed differences between activated carbons and CNT materials. For the limited data set here, the Raman D:G ratio as a measure of disordered non-nanotube graphitic components was not a good predictor of adsorption from solution. Uptake of atrazine by MWNTs having a range of lengths and diameters was comparable and their Freundlich isotherms were statistically similar, and we found no impact of solution pH on the adsorption of either atrazine or trichloroethylene in the range of naturally occurring surface water (pH = 5.7-8.3). Experiments were performed using a suite of model aromatic compounds having a range of ?-electron energy to investigate the role of ?-? electron donor-acceptor interactions on organic compound uptake by SWNTs. For the compounds studied, hydrophobic interactions were the dominant mechanism in the uptake by both SWNTs and activated carbon. However, comparing the uptake of naphthalene and phenanthrene by activated carbon and SWNTs, size exclusion effects appear to be more pronounced with activated carbon materials, perhaps due to smaller pore sizes or larger adsorption surface areas in small pores.

Brooks, A. J.; Lim, Hyung-nam; Kilduff, James E.

2012-07-01

388

Clinical and radiographic study of activated carbon workers.  

PubMed Central

Activated carbon is made in Sri Lanka by passing steam through charcoal made from coconut shells. The carbon does not contain free silica. Sixty six men who had worked in a factory making activated carbon for an average of 7.2 years had no more respiratory symptoms than a control group, and none showed radiological evidence of pneumoconiosis. There was no evidence that people exposed to charcoal and pure carbon for up to 11 years are at risk of developing pneumoconiosis. PMID:2763231

Uragoda, C G

1989-01-01

389

Effects of acidic treatment of activated carbons on dye adsorption  

Microsoft Academic Search

The effect of acidic treatments of activated carbons on dye adsorption was investigated. The physico-chemical properties of activated carbons were characterised by N2 adsorption, mass titration, temperature-programmed desorption (TPD), and X-ray photoelectron spectrometry (XPS). It was found that surface chemistry plays an important role in dye adsorption. HNO3 treatment produces more active acidic surface groups such as carboxyl and lactone,

Shaobin Wang; Z. H. Zhu

2007-01-01

390

Preparation and characterization of PVA-I complex doped mesoporous TiO2 by hydrothermal method  

NASA Astrophysics Data System (ADS)

Polyvinyl alcohol [PVA]-iodine complex doped mesoporous TiO2 (PIT) and iodine doped (IT) catalysts were prepared by hydrothermal method, using tetrabutyl titanate as precursor, potassium iodate and iodine as iodine sources. The as-prepared PIT and IT catalysts were characterized by UV-vis, XRD, FESEM, BET, TG/DTA, XPS and photoluminescence (PL) spectroscopy. Production of rad OH radicals on the surface of photocatalyst was detected by the PL technique using terephthalic acid as a probe molecule. The influences of calcinated temperature on the structure and properties of the catalysts were investigated. The photocatalytic activity of catalysts was evaluated through photocatalytic decolorization of methylene blue (MB) aqueous solution. The results showed that PIT samples were anatase mesoporous TiO2 and their iodine content and mesoporous structure were influenced by calcinated temperature. Particle size of PIT samples was smaller than that of IT as a result of the PVA skeleton and regular structure. Because of the complexation of iodine and PVA, thermostability of iodine is improved and the amount of iodine in PIT calcinated at 200 °C (PIT-200) is higher than that of IT calcinated at same temperature. Light absorption range and intensity of PIT-200 has been greatly improved due to the synergy of iodine and carbon. The efficiency of photocatalysis for MB is greatly improved with TiO2 modified by PVA-I complex under simulated sun light irradiation.

Shi, Qian; Jiang, Caiyun; Wang, Yuping; Yang, Weiben; Yang, Chun

2013-05-01

391

Thermodynamic characterization of a regenerated activated carbon surface  

NASA Astrophysics Data System (ADS)

Calorimetric measurements of the immersion enthalpy in different liquids of a set of regenerated activated carbons have been employed to analyze the effect of a regeneration process on the extension of the accessible surface area and the hydrophobic character of the carbons by comparison with the original carbon. The modifications in the hydrophobicity of the activated carbons are quantified by the analysis of the surface free energy of the solids and its dispersion and non-dispersion components. It has been found that regeneration treatment of the original carbon increases its accessible surface area and hydrophobicity. However, the opposite effects take place when regeneration is done on the same carbon previously saturated with p-nitrophenol (PNP) or p-chlorophenol (PClP).

González-Martín, M. L.; González-García, C. M.; González, J. F.; Ramiro, A.; Sabio, E.; Bruque, J. M.; Encinar, J. M.

2002-05-01

392

PRODUCTION OF ACTIVATED CARBON FROM SAWDUST USING FLUIDIZED BED REACTOR  

Microsoft Academic Search

ABSTARCT Activated carbon was produced from sawdust by using steam activation in a high temperature muffle furnace. Fast pyrolysis process was carried out prior in fluidized a bed furnace to produce char before activation process. Experiments were conducted to investigate the influence of various process parameters such as particle size, pyrolysis temperature and activation time on the quality of the

MAN KEE LAM; RIDZUAN ZAKARIA

393

Reprocessing of used tires into activated carbon and other products  

SciTech Connect

Landfilling used tires which are generated each year in the US is increasingly becoming an unacceptable solution. A better approach, from an environmental and economic standpoint, is to thermally reprocess the tires into valuable products such as activated carbon, other solid carbon forms (carbon black, graphite, and carbon fibers), and liquid fuels. In this study, high surface area activated carbons (> 800 m{sup 2}/g solid product) were produced in relatively high yields by pyrolysis of tires at up to 900 C, followed by activation in CO{sub 2} at the same temperature. The surface areas of these materials are comparable with those of commercial activated carbons. The efficiency of the activation process (gain in specific surface area/loss in mass) was greatest (up to 138 m{sup 2}/g original tire) when large pieces of tire material were used ({approximately} 170 mg). Oxygen pretreatment of tires was found to enhance both the yield and the surface area of the carbon product. High-pressure treatment of tires at low temperatures (< 400 C) is an alternative approach if the recovery of carbon black or fuel oils is the primary objective.

Teng, H.; Serio, M.A.; Wojtowicz, M.A.; Bassilakis, R.; Solomon, P.R. [Advanced Fuel Research, Inc., East Hartford, CT (United States)

1995-09-01

394

Effects of activation method on the pore structure of activated carbons from apricot stones  

Microsoft Academic Search

Two series of activated carbons were prepared from apricot stones by using carbonization followed by steam activation and one-step pyrolysis\\/activation in steam. The pore structure of the activated carbons was characterized by CO2 adsorption at 273 K and by N2 adsorption at 77 K. The macro- and mesoporosity were determined by mercury porosimetry. Optical microscopy, scanning electron microscopy (SEM) and

K. Gergova; S. Eser

1996-01-01

395

JV Task 90 - Activated Carbon Production from North Dakota Lignite  

SciTech Connect

The Energy & Environmental Research Center (EERC) has pursued a research program for producing activated carbon from North Dakota lignite that can be competitive with commercial-grade activated carbon. As part of this effort, small-scale production of activated carbon was produced from Fort Union lignite. A conceptual design of a commercial activated carbon production plant was drawn, and a market assessment was performed to determine likely revenue streams for the produced carbon. Activated carbon was produced from lignite coal in both laboratory-scale fixed-bed reactors and in a small pilot-scale rotary kiln. The EERC was successfully able to upgrade the laboratory-scale activated carbon production system to a pilot-scale rotary kiln system. The activated carbon produced from North Dakota lignite was superior to commercial grade DARCO{reg_sign} FGD and Rheinbraun's HOK activated coke product with respect to iodine number. The iodine number of North Dakota lignite-derived activated carbon was between 600 and 800 mg I{sub 2}/g, whereas the iodine number of DARCO FGD was between 500 and 600 mg I{sub 2}/g, and the iodine number of Rheinbraun's HOK activated coke product was around 275 mg I{sub 2}/g. The EERC performed both bench-scale and pilot-scale mercury capture tests using the activated carbon made under various optimization process conditions. For comparison, the mercury capture capability of commercial DARCO FGD was also tested. The lab-scale apparatus is a thin fixed-bed mercury-screening system, which has been used by the EERC for many mercury capture screen tests. The pilot-scale systems included two combustion units, both equipped with an electrostatic precipitator (ESP). Activated carbons were also tested in a slipstream baghouse at a Texas power plant. The results indicated that the activated carbon produced from North Dakota lignite coal is capable of removing mercury from flue gas. The tests showed that activated carbon with the greatest iodine number was superior to commercial DARCO FGD for mercury capture. The results of the activated carbon market assessment indicate an existing market for water treatment and an emerging application for mercury control. That market will involve both existing and new coal-fired plants. It is expected that 20% of the existing coal-fired plants will implement activated carbon injection by 2015, representing about 200,000 tons of annual demand. The potential annual demand by new plants is even greater. In the mercury control market, two characteristics are going to dominate the customer's buying habit-performance and price. As continued demonstration testing of activated carbon injection at the various coal-fired power plants progresses, the importance of fuel type and plant configuration on the type of activated carbon best suited is being identified.

Steven Benson; Charlene Crocker; Rokan Zaman; Mark Musich; Edwin Olson

2008-03-31

396

Activated carbon fibers and engineered forms from renewable resources  

DOEpatents

A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

Baker, Frederick S

2013-02-19

397

Liquid-phase adsorption of organic compounds by granular activated carbon and activated carbon fibers  

SciTech Connect

Liquid-phase adsorption of organic compounds by granular activated carbon (GAC) and activated carbon fibers (ACFs) is investigated. Acetone, isopropyl alcohol (IPA), phenol, and tetrahydrofuran (THF) were employed as the model compounds for the present study. It is observed from the experimental results that adsorption of organic compounds by GAC and ACF is influenced by the BET (Brunauer-Emmett-Teller) surface area of adsorbent and the molecular weight, polarity, and solubility of the adsorbate. The adsorption characteristics of GAC and ACFs were found to differ rather significantly. In terms of the adsorption capacity of organic compounds, the time to reach equilibrium adsorption, and the time for complete desorption, ACFs have been observed to be considerably better than GAC. For the organic compounds tested here, the GAC adsorptions were shown to be represented well by the Langmuir isoth