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Sample records for activated carbon zeolite

  1. Supercritical adsorption testing of porous silicon, activated carbon, and zeolite materials

    NASA Astrophysics Data System (ADS)

    Harvey, Brendan

    The supercritical adsorption of methane gas on porous silicon, activated carbon, and zeolite materials was studied. An apparatus that utilizes the volumetric adsorption measurement technique was designed and constructed to conduct the experiments. Activated carbon materials consisted of Norit RX3 Extra, Zorflex FM30K woven activated carbon cloth, and Zorflex FM10 knitted activated carbon cloth. Zeolite materials consisted of 3A, 4A, 5A, and 13X zeolites. Porous silicon materials consisted of stain etched and electrochemically etched porous films, and stain etched porous powder. All adsorption tests were conducted at room temperature (approximately 298 K) and pressures up to approximately 5 MPa. Overall, the Norit RX3 Extra granulated activated carbon produced the highest excess adsorption and effective storage capacities. Effective storage and delivery capacities of 109 and 90 stpmlml were obtained at a pressure of 3.5 MPa and a temperature of approximately 298 K.

  2. Desorption kinetics of N,N-dimethylformamide vapor from granular activated carbon and hydrophobic zeolite

    SciTech Connect

    Ching-Yuan Chang; Wen-Tien Tsai; Horng-Chia Lee

    1996-07-01

    Such thermodynamic properties as enthalpy, free energy, and entropy of adsorption have been computed for N,N-dimethylformamide (DMF) vapor on two commercial adsorbents: coconut shell Type PCB of activated carbon and Type DAY of hydrophobic zeolite. The computation is based on the Langmuir adsorption isotherms obtained at 293, 303, and 313 K as reported by Tsai et al. The laden adsorbents were regenerated with hot inert nitrogen gas and studied by thermal gravimetric analysis at three different heating rates. The apparent activation energies (E{sub des}) of thermal desorption were determined by using the Friedman method. The zeolite DAY has an adsorption potential higher than that of activated carbon PCB as indicated by the more negative value of the adsorption enthalpy of DMF vapor. The average value of E{sub des} of zeolite DAY is larger than that of activated carbon PCB.

  3. Removal of perfluorinated surfactants by sorption onto granular activated carbon, zeolite and sludge.

    PubMed

    Ochoa-Herrera, Valeria; Sierra-Alvarez, Reyes

    2008-08-01

    Perfluorinated surfactants are emerging pollutants of increasing public health and environmental concern due to recent reports of their world-wide distribution, environmental persistence and bioaccumulation potential. Treatment methods for the removal of anionic perfluorochemical (PFC) surfactants from industrial effluents are needed to minimize the environmental release of these pollutants. Removal of PFC surfactants from aqueous solutions by sorption onto various types of granular activated carbon was investigated. Three anionic PFC surfactants, i.e., perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutane sulfonate (PFBS), were evaluated for the ability to adsorb onto activated carbon. Additionally, the sorptive capacity of zeolites and sludge for PFOS was compared to that of granular activated carbon. Adsorption isotherms were determined at constant ionic strength in a pH 7.2 phosphate buffer at 30 degrees C. Sorption of PFOS onto activated carbon was stronger than PFOA and PFBS, suggesting that the length of the fluorocarbon chain and the nature of the functional group influenced sorption of the anionic surfactants. Among all adsorbents evaluated in this study, activated carbon (Freundlich K(F) values=36.7-60.9) showed the highest affinity for PFOS at low aqueous equilibrium concentrations, followed by the hydrophobic, high-silica zeolite NaY (Si/Al 80, K(F)=31.8), and anaerobic sludge (K(F)=0.95-1.85). Activated carbon also displayed a superior sorptive capacity at high soluble concentrations of the surfactant (up to 80 mg l(-1)). These findings indicate that activated carbon adsorption is a promising treatment technique for the removal of PFOS from dilute aqueous streams. PMID:18511099

  4. Use of activated carbon and natural zeolite as support materials, in an anaerobic fluidised bed reactor, for vinasse treatment.

    PubMed

    Fernández, N; Fdz-Polanco, F; Montalvo, S J; Toledano, D

    2001-01-01

    In Cuba, the alcohol distillation process from cane sugar molasses, produces a final waste (vinasse), with an enormous polluting potential and a high sulfate content. Applying the anaerobic technology, most of the biodegradable organic matter can turn into biogas, rich in methane but with concentrations of sulfide above 1%. The present work develops two experiences with anaerobic fluidized bed reactors (AFBR) using both Cuban raw material, activated carbon and natural zeolite, as support media, with the purpose of obtaining high organic matter removal rates and keeping sulfide and ammonium concentrations in the permissible ranges. The reactors were operated during 120 days, achieving an organic loading rate of 10 kg COD/m3 day, with COD removal above 70%, and a methane production of 2 L/d. The activated carbon and natural zeolite used support materials in anaerobic fluidized bed reactors, and showed good results of distillery waste removal. PMID:11575071

  5. Recovery of N and P from human urine by freezing, struvite precipitation and adsorption to zeolite and active carbon.

    PubMed

    Ganrot, Zsófia; Dave, Göran; Nilsson, Eva

    2007-11-01

    The majority of the nutrients in domestic waste originate from human urine. This study deals with methods for recovery of N and P from urine. Results from a freezing-thawing method (FTM) together with struvite recovery and nitrogen adsorption on zeolite and active carbon (AC) are presented. Various amounts of MgO, zeolite and AC were added to samples of 100ml urine. After 3 days the supernatants were analysed for pH, total-N, total-P and acute toxicity for Daphnia magna. One set of samples was frozen and then thawed and the supernatants collected were tested as before. The FTM method concentrated 60% of the nutrients in 40% of the initial volume and significantly improved the N reduction and D. magna survival. The P recovery was 95-100%, mainly as struvite. No significant effect of AC was found. Zeolite improved the P recovery and in some combinations of MgO also the N recovery. PMID:17321132

  6. Combination of powdered activated carbon and powdered zeolite for enhancing ammonium removal in micro-polluted raw water.

    PubMed

    Liao, Zhen-Liang; Chen, Hao; Zhu, Bai-Rong; Li, Huai-Zheng

    2015-09-01

    Even zeolite is promising in ammonia pollution disposing, its removal efficiency is frequently interfered by organics. As activated carbon has good removal efficiency on organic contaminants, combination of two adsorbents may allow their respective adsorption characteristics into full play. This paper provides a performance assessment of the combination for enhancing ammonium removal in micro-polluted raw water. Gel-filtration chromatography (GFC) was carried out to quantify the molecular weight (MW) range of organic contaminants that powdered activated carbon (PAC) and powdered zeolite (PZ) can remove. The polydispersity difference which also calculated from GFC may indicate the wider organic contaminants removal range of PAC and the relatively centralized removal range of PZ. The jar tests of combination dosing confirm a synergistic effect which promotes ammonium removing. Nevertheless, it also shows an antagonism hindering the due removal performance of the two adsorbents on CODMn, while it is not much evident on UV254. Furthermore, a comparison study with simulated coagulation-sedimentation process was conducted to evaluate the optimum dosing points (spatial and temporal) of PAC and PZ among follows: suction well, pipeline mixer, early and middle phase of flocculation. We suggest to dose both two adsorbents into the early phase of flocculation to maximize the versatile removal efficiency on turbidity, ammonium and organic contaminants. PMID:25929873

  7. Removal of xenobiotics from effluent discharge by adsorption on zeolite and expanded clay: an alternative to activated carbon?

    PubMed

    Tahar, A; Choubert, J M; Miège, C; Esperanza, M; Le Menach, K; Budzinski, H; Wisniewski, C; Coquery, M

    2014-04-01

    Xenobiotics such as pesticides and pharmaceuticals are an increasingly large problem in aquatic environments. A fixed-bed adsorption filter, used as tertiary stage of sewage treatment, could be a solution to decrease xenobiotics concentrations in wastewater treatment plants (WWTPs) effluent. The adsorption efficiency of two mineral adsorbent materials (expanded clay (EC) and zeolite (ZE)), both seen as a possible alternative to activated carbon (AC), was evaluated in batch tests. Experiments involving secondary treated domestic wastewater spiked with a cocktail of ten xenobiotics (eight pharmaceuticals and two pesticides) known to be poorly eliminated in conventional biological process were carried out. Removal efficiencies and partitions coefficients were calculated for two levels of initial xenobiotic concentration, i.e, concentrations lower to 10 μg/L and concentrations ranged from 100 to 1,000 μg/L. While AC was the most efficient adsorbent material, both alternative adsorbent materials showed good adsorption efficiencies for all ten xenobiotics (from 50 to 100 % depending on the xenobiotic/adsorbent material pair). For all the targeted xenobiotics, at lower concentrations, EC presented the best adsorption potential with higher partition coefficients, confirming the results in terms of removal efficiencies. Nevertheless, Zeolite presents virtually the same adsorption potential for both high and low xenobiotics concentrations to be treated. According to this first batch investigation, ZE and EC could be used as alternative absorbent materials to AC in WWTP. PMID:24430496

  8. Comparisons of kinetics, thermodynamics and regeneration of tetramethylammonium hydroxide adsorption in aqueous solution with graphene oxide, zeolite and activated carbon

    NASA Astrophysics Data System (ADS)

    Chang, Shenteng; Lu, Chungsying; Lin, Kun-Yi Andrew

    2015-01-01

    Graphene oxide (GO), sodium Y-type zeolite (NaY) and granular activated carbon (GAC) are selected as adsorbents to study their kinetics, thermodynamics and regeneration of tetramethylammonium hydroxide (TMAH) adsorption from water. The adsorption kinetics follows the pseudo-second-order rate law while the adsorption thermodynamics shows an exothermic reaction with GO and GAC but displays an endothermic reaction with NaY. The adsorbed TMAH can be readily desorbed from the surface of GO and NaY by 0.05 M NaCl solution. A comparative study on the cyclic TMAH adsorption with GO, NaY and GAC is also conducted and the results reveal that GO exhibits the greatest TMAH adsorption capacity as well as superior reversibility of TMAH adsorption over 10 cycles of adsorption and desorption process. These features indicate that GO is a promising and efficient adsorbent for TMAH removal in wastewater treatment.

  9. Application of zeolite-activated carbon macrocomposite for the adsorption of Acid Orange 7: isotherm, kinetic and thermodynamic studies.

    PubMed

    Lim, Chi Kim; Bay, Hui Han; Neoh, Chin Hong; Aris, Azmi; Abdul Majid, Zaiton; Ibrahim, Zaharah

    2013-10-01

    In this study, the adsorption behavior of azo dye Acid Orange 7 (AO7) from aqueous solution onto macrocomposite (MC) was investigated under various experimental conditions. The adsorbent, MC, which consists of a mixture of zeolite and activated carbon, was found to be effective in removing AO7. The MC were characterized by scanning electron microscopy (SEM), energy dispersive X-ray, point of zero charge, and Brunauer-Emmett-Teller surface area analysis. A series of experiments were performed via batch adsorption technique to examine the effect of the process variables, namely, contact time, initial dye concentration, and solution pH. The dye equilibrium adsorption was investigated, and the equilibrium data were fitted to Langmuir, Freundlich, and Tempkin isotherm models. The Langmuir isotherm model fits the equilibrium data better than the Freundlich isotherm model. For the kinetic study, pseudo-first-order, pseudo-second-order, and intraparticle diffusion model were used to fit the experimental data. The adsorption kinetic was found to be well described by the pseudo-second-order model. Thermodynamic analysis indicated that the adsorption process is a spontaneous and endothermic process. The SEM, Fourier transform infrared spectroscopy, ultraviolet-visible spectral and high performance liquid chromatography analysis were carried out before and after the adsorption process. For the phytotoxicity test, treated AO7 was found to be less toxic. Thus, the study indicated that MC has good potential use as an adsorbent for the removal of azo dye from aqueous solution. PMID:23653315

  10. Investigation of the adsorption of water vapor and carbon dioxide by KA zeolite

    SciTech Connect

    Khanitonov, V.P.; Shtein, A.S.

    1984-05-01

    According to the present data, KA zeolite, which can adsorb only water vapor, helium, and hydrogen, has the greatest selectivity in drying. The feasibility of using this zeolite in devices for selective drying of gases used in gas-analysis systems was studied. The results of the experiments were approximated by the thermal equation of the theory of bulk filling of micropores. The limiting value of the adsorption depends on the temperature, and it can be calculated according to the density of the adsorbed phase and the adsorption volume. The critical diameters of the water and carbon dioxide molecules are close to the dimensions of the KA-zeolite pores, something that determines the activated nature of the adsorption of these substances. Experiments on coadsorption of water vapor and carbon dioxide by a fixed bed of KA-zeolite under dynamic conditions showed that the adsorption of these substances has a frontal nature. The time of the protective action of the layer of zeolite during adsorption af water vapor exceeded by more than an order the time of the protective action during adsorption of carbon dioxide. The results showed that this adsorbent can be used for selective drying of gas mixtures containing carbon dioxide in batch-operation devices. Beforehand, the adsorbent should be regenerated with respect to moisture, and then it should be saturated with carbon dioxide by blowing the adsorbent with a gas mixture of the working composition until the equilibrium state is reached.

  11. DFT investigations for the reaction mechanism of dimethyl carbonate synthesis on Pd(II)/β zeolites.

    PubMed

    Shen, Yongli; Meng, Qingsen; Huang, Shouying; Gong, Jinlong; Ma, Xinbin

    2013-08-21

    Density functional theory (DFT) calculations have been used to investigate the oxidative carbonylation of methanol on Pd(II)/β zeolite. Activation energies for all the elementary steps involved in the commonly accepted mechanism, including the formation of dimethyl carbonate, methyl formate and dimethoxymethane, are presented. Upon conducting the calculations, we identify that the Pd(2+) cation bonded with four O atoms of the zeolite framework acts as the active site of the catalyst. Molecularly adsorbed methanol starts to react with oxygen molecules to produce a methanediol intermediate (CH2(OH)2) and O atom. Then, another methanol can react with the O atom to produce the (CH3O)(OH)-Pd(II)/β zeolite species. (CH3O)(OH)-Pd(II)/β zeolite can further react with carbon monoxide or methanol to give monomethyl carbonate or di-methoxide species ((CH3O)2-Pd(II)/β zeolite). Dimethyl carbonate can form via two distinct reaction pathways: (I) methanol reacts with monomethyl carbonate or (II) carbon monoxide inserts into di-methoxide. Our calculation results show the activation energy of reaction (I) is too high to be achieved. The methanediol intermediate is unstable and can decompose to formaldehyde and H2O immediately. Formaldehyde can either react with an O atom or methanol to form formic acid or a CH3OCH2OH intermediate. Both of them can react with methanol to form the secondary products (methyl formate or dimethoxymethane). Upon conducting calculations, we confirmed that the activation energies for the formation of methyl formate and dimethoxymethane are higher than that of dimethyl carbonate. All these conformations were characterized at the same calculation level. PMID:23824280

  12. Lanthanum-catalysed synthesis of microporous 3D graphene-like carbons in a zeolite template

    NASA Astrophysics Data System (ADS)

    Kim, Kyoungsoo; Lee, Taekyoung; Kwon, Yonghyun; Seo, Yongbeom; Song, Jongchan; Park, Jung Ki; Lee, Hyunsoo; Park, Jeong Young; Ihee, Hyotcherl; Cho, Sung June; Ryoo, Ryong

    2016-07-01

    Three-dimensional graphene architectures with periodic nanopores—reminiscent of zeolite frameworks—are of topical interest because of the possibility of combining the characteristics of graphene with a three-dimensional porous structure. Lately, the synthesis of such carbons has been approached by using zeolites as templates and small hydrocarbon molecules that can enter the narrow pore apertures. However, pyrolytic carbonization of the hydrocarbons (a necessary step in generating pure carbon) requires high temperatures and results in non-selective carbon deposition outside the pores. Here, we demonstrate that lanthanum ions embedded in zeolite pores can lower the temperature required for the carbonization of ethylene or acetylene. In this way, a graphene-like carbon structure can be selectively formed inside the zeolite template, without carbon being deposited at the external surfaces. X-ray diffraction data from zeolite single crystals after carbonization indicate that electron densities corresponding to carbon atoms are generated along the walls of the zeolite pores. After the zeolite template is removed, the carbon framework exhibits an electrical conductivity that is two orders of magnitude higher than that of amorphous mesoporous carbon. Lanthanum catalysis allows a carbon framework to form in zeolite pores with diameters of less than 1 nanometre; as such, microporous carbon nanostructures can be reproduced with various topologies corresponding to different zeolite pore sizes and shapes. We demonstrate carbon synthesis for large-pore zeolites (FAU, EMT and beta), a one-dimensional medium-pore zeolite (LTL), and even small-pore zeolites (MFI and LTA). The catalytic effect is a common feature of lanthanum, yttrium and calcium, which are all carbide-forming metal elements. We also show that the synthesis can be readily scaled up, which will be important for practical applications such as the production of lithium-ion batteries and zeolite-like catalyst

  13. Lanthanum-catalysed synthesis of microporous 3D graphene-like carbons in a zeolite template.

    PubMed

    Kim, Kyoungsoo; Lee, Taekyoung; Kwon, Yonghyun; Seo, Yongbeom; Song, Jongchan; Park, Jung Ki; Lee, Hyunsoo; Park, Jeong Young; Ihee, Hyotcherl; Cho, Sung June; Ryoo, Ryong

    2016-07-01

    Three-dimensional graphene architectures with periodic nanopores—reminiscent of zeolite frameworks—are of topical interest because of the possibility of combining the characteristics of graphene with a three-dimensional porous structure. Lately, the synthesis of such carbons has been approached by using zeolites as templates and small hydrocarbon molecules that can enter the narrow pore apertures. However, pyrolytic carbonization of the hydrocarbons (a necessary step in generating pure carbon) requires high temperatures and results in non-selective carbon deposition outside the pores. Here, we demonstrate that lanthanum ions embedded in zeolite pores can lower the temperature required for the carbonization of ethylene or acetylene. In this way, a graphene-like carbon structure can be selectively formed inside the zeolite template, without carbon being deposited at the external surfaces. X-ray diffraction data from zeolite single crystals after carbonization indicate that electron densities corresponding to carbon atoms are generated along the walls of the zeolite pores. After the zeolite template is removed, the carbon framework exhibits an electrical conductivity that is two orders of magnitude higher than that of amorphous mesoporous carbon. Lanthanum catalysis allows a carbon framework to form in zeolite pores with diameters of less than 1 nanometre; as such, microporous carbon nanostructures can be reproduced with various topologies corresponding to different zeolite pore sizes and shapes. We demonstrate carbon synthesis for large-pore zeolites (FAU, EMT and beta), a one-dimensional medium-pore zeolite (LTL), and even small-pore zeolites (MFI and LTA). The catalytic effect is a common feature of lanthanum, yttrium and calcium, which are all carbide-forming metal elements. We also show that the synthesis can be readily scaled up, which will be important for practical applications such as the production of lithium-ion batteries and zeolite-like catalyst

  14. Multi-wall carbon nanotube@zeolite imidazolate framework composite from a nanoscale zinc oxide precursor

    DOE PAGESBeta

    Yue, Yanfeng; Guo, Bingkun; Qiao, Zhenan; Fulvio, Pasquale F.; Chen, Jihua; Binder, Andrew J.; Tian, Chengcheng; Dai, Sheng

    2014-07-24

    Nanocomposite of multi-walled carbon nanotube@zeolite imidazolate frameworks (MWNT@ZIF) was prepared through a nanotube-facilitated growth based on a nanosized ZnO precursor. The electrically conductive nanocomposite displays a capacity of 380 mAh/g at 0.1 °C in Li–sulfur battery, transforming electrically inactive ZIF into the active one for battery applications.

  15. Titanium-based zeolitic imidazolate framework for chemical fixation of carbon dioxide

    EPA Science Inventory

    A titanium-based zeolitic imidazolate framework (Ti-ZIF) with high surface area and porous morphology was synthesized and itsefficacy was demonstrated in the synthesis of cyclic carbonates from epoxides and carbon dioxide.

  16. Catalytic activities of zeolite compounds for decomposing aqueous ozone.

    PubMed

    Kusuda, Ai; Kitayama, Mikito; Ohta, Yoshio

    2013-12-01

    The advanced oxidation process (AOP), chemical oxidation using aqueous ozone in the presence of appropriate catalysts to generate highly reactive oxygen species, offers an attractive option for removing poorly biodegradable pollutants. Using the commercial zeolite powders with various Si/Al ratios and crystal structures, their catalytic activities for decomposing aqueous ozone were evaluated by continuously flowing ozone to water containing the zeolite powders. The hydrophilic zeolites (low Si/Al ratio) with alkali cations in the crystal structures were found to possess high catalytic activity for decomposing aqueous ozone. The hydrophobic zeolite compounds (high Si/Al ratio) were found to absorb ozone very well, but to have no catalytic activity for decomposing aqueous ozone. Their catalytic activities were also evaluated by using the fixed bed column method. When alkali cations were removed by acid rinsing or substituted by alkali-earth cations, the catalytic activities was significantly deteriorated. These results suggest that the metal cations on the crystal surface of the hydrophilic zeolite would play a key role for catalytic activity for decomposing aqueous ozone. PMID:25078817

  17. Characterization and antibacterial activity of silver exchanged regenerated NaY zeolite from surfactant-modified NaY zeolite.

    PubMed

    Salim, Mashitah Mad; Malek, Nik Ahmad Nizam Nik

    2016-02-01

    The antibacterial activity of regenerated NaY zeolite (thermal treatment from cetyltrimethyl ammonium bromide (CTAB)-modified NaY zeolite and pretreatment with Na ions) loaded with silver ions were examined using the broth dilution minimum inhibitory concentration (MIC) method against Escherichia coli (E. coli ATCC 11229) and Staphylococcus aureus (S. aureus ATCC 6538). X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and chemical elemental analyses were used to characterize the regenerated NaY and AgY zeolites. The XRD patterns indicated that the calcination and addition of silver ions on regenerated NaY zeolite did not affect the structure of the regenerated NaY zeolite as the characteristic peaks of the NaY zeolite were retained, and no new peaks were observed. The regenerated AgY zeolite showed good antibacterial activity against both bacteria strains in distilled water, and the antibacterial activity of the samples increased with increasing Ag loaded on the regenerated AgY zeolite; the regenerated AgY zeolite was more effective against E. coli than S. aureus. However, the antibacterial activity of the regenerated AgY was not effective in saline solution for both bacteria. The study showed that CTAB-modified NaY zeolite materials could be regenerated to NaY zeolite using thermal treatment (550°C, 5h) and this material has excellent performance as an antibacterial agent after silver ions loading. PMID:26652350

  18. Synthesis of Na-A and/or Na-X zeolite/porous carbon composites from carbonized rice husk

    NASA Astrophysics Data System (ADS)

    Katsuki, Hiroaki; Komarneni, Sridhar

    2009-07-01

    Na-A and/or Na-X zeolite/porous carbon composites were prepared under hydrothermal conditions by NaOH dissolution of silica first from carbonized rice husk followed by addition of NaAlO 2 and in situ crystallization of zeolites i.e., using a two-step process. When a one-step process was used, both Na-A and Na-X zeolites crystallized on the surface of carbon. Na-A or Na-X zeolite crystals were prepared on the porous carbonized rice husk at 90 °C for 2-6 h by changing the SiO 2/Al 2O 3, H 2O/Na 2O and Na 2O/SiO 2 molar ratios of precursors in the two-step process. The surface area and NH 4+-cation exchange capacity (CEC) of Na-A zeolite/porous carbon were found to be 171 m 2/g and 506 meq/100 g, respectively, while those of Na-X zeolite/porous carbon composites were 676 m 2/g and 317 meq/100 g, respectively. Na-A and Na-X zeolites are well-known microporous and hydrophilic materials while carbonized rice husk was found to be mesoporous (pores of ˜3.9 nm) and hydrophobic. These hybrid microporous-mesoporous and hydrophilic-hydrophobic composites are expected to be useful for decontamination of metal cations as well as organic contaminants simultaneously.

  19. Synthesis of Na-A and/or Na-X zeolite/porous carbon composites from carbonized rice husk

    SciTech Connect

    Katsuki, Hiroaki; Komarneni, Sridhar

    2009-07-15

    Na-A and/or Na-X zeolite/porous carbon composites were prepared under hydrothermal conditions by NaOH dissolution of silica first from carbonized rice husk followed by addition of NaAlO{sub 2} and in situ crystallization of zeolites i.e., using a two-step process. When a one-step process was used, both Na-A and Na-X zeolites crystallized on the surface of carbon. Na-A or Na-X zeolite crystals were prepared on the porous carbonized rice husk at 90 deg. C for 2-6 h by changing the SiO{sub 2}/Al{sub 2}O{sub 3}, H{sub 2}O/Na{sub 2}O and Na{sub 2}O/SiO{sub 2} molar ratios of precursors in the two-step process. The surface area and NH{sub 4}{sup +}-cation exchange capacity (CEC) of Na-A zeolite/porous carbon were found to be 171 m{sup 2}/g and 506 meq/100 g, respectively, while those of Na-X zeolite/porous carbon composites were 676 m{sup 2}/g and 317 meq/100 g, respectively. Na-A and Na-X zeolites are well-known microporous and hydrophilic materials while carbonized rice husk was found to be mesoporous (pores of {approx}3.9 nm) and hydrophobic. These hybrid microporous-mesoporous and hydrophilic-hydrophobic composites are expected to be useful for decontamination of metal cations as well as organic contaminants simultaneously. - Graphical Abstract: Novel Na-X zeolite/porous carbon composite.

  20. Superconducting characteristics of 4-Å carbon nanotube–zeolite composite

    PubMed Central

    Lortz, Rolf; Zhang, Qiucen; Shi, Wu; Ye, Jian Ting; Qiu, Chunyin; Wang, Zhe; He, Hongtao; Sheng, Ping; Qian, Tiezheng; Tang, Zikang; Wang, Ning; Zhang, Xixiang; Wang, Jiannong; Chan, Che Ting

    2009-01-01

    We have fabricated nanocomposites consisting of 4-Å carbon nanotubes embedded in the 0.7-nm pores of aluminophosphate-five (AFI) zeolite that display a superconducting specific heat transition at 15 K. MicroRaman spectra of the samples show strong and spatially uniform radial breathing mode (RBM) signals at 510 cm−1 and 550 cm−1, characteristic of the (4, 2) and (5, 0) nanotubes, respectively. The specific heat transition is suppressed at >2 T, with a temperature dependence characteristic of finite-size effects. Comparison with theory shows the behavior to be consistent with that of a type II BCS superconductor, characterized by a coherence length of 14 ± 2 nm and a magnetic penetration length of 1.5 ± 0.7 μm. Four probe and differential resistance measurements have also indicated a superconducting transition initiating at 15 K, but the magnetoresistance data indicate the superconducting network to be inhomogeneous, with a component being susceptible to magnetic fields below 3 T and other parts capable of withstanding a magnetic field of 5 T or beyond. PMID:19369206

  1. Removal of carbon monoxide. Physical adsorption on natural and synthetic zeolites

    NASA Technical Reports Server (NTRS)

    Alfani, F.; Greco, G., Jr.; Iroio, G.

    1982-01-01

    The utilization of natural zeolite materials in the elimination of polluting gases is investigated. Carbon monoxide pollution is emphasized because its concentration may reach dangerous levels in places such as vehicle tunnels, underground parking lots, etc. The elimination of carbon monoxide is also of interest in some industrial processes relating to the production of pure gases.

  2. Catalase-like activity studies of the manganese(II) adsorbed zeolites

    NASA Astrophysics Data System (ADS)

    Ćiçek, Ekrem; Dede, Bülent

    2013-12-01

    Preparation of manganese(II) adsorbed on zeolite 3A, 4A, 5A. AW-300, ammonium Y zeolite, organophilic, molecular sieve and catalase-like enzyme activity of manganese(II) adsorbed zeolites are reported herein. Firstly zeolites are activated at 873 K for two hours before contact manganese(II) ions. In order to observe amount of adsorption, filtration process applied for the solution. The pure zeolites and manganese(II) adsorbed zeolites were analysed by FT-IR. As a result according to the FT-IR spectra, the incorporation of manganese(II) cation into the zeolite structure causes changes in the spectra. These changes are expected particularly in the pseudolattice bands connected with the presence of alumino and silicooxygen tetrahedral rings in the zeolite structure. Furthermore, the catalytic activities of the Mn(II) adsorbed zeolites for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The Mn(II) adsorbed zeolites display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity.

  3. Effects of carbon-to-zeolite ratio on layered bed H{sub 2} PSA for coke oven gas

    SciTech Connect

    Lee, C.H.; Yang, J.; Ahn, H.

    1999-03-01

    Effects of carbon-to-zeolite ratio on a layered bed H{sub 2} PSA using activated carbon and zeolite 5A were studied experimentally and theoretically. Coke oven gas (56.,4 vol.% H{sub 2}, 26.6 vol.% CH{sub 4}, 8.4 vol.% CO, 5.5 vol. % N{sub 2}, and 3.1 vol.% CO{sub 2}) was used as a feed gas for the seven-step two-bed PSA process incorporating a backfill step. In these experiments, the effects of three operating variables such as adsorption pressure, feed rate and purge rate on the performance of a layered bed PSA were investigated. The layered bed gave better purity than the single-adsorbent bed at the same operating condition, except at low purge rate. Since every component had its own front velocity at each layer, a carbon-to-zeolite ratio affected product purity at a given recovery or throughput. Moreover, for a high-purity H{sub 2} product from coke oven gas, an optimum carbon-to-zeolite ratio had to be determined to control a leading wavefront of N{sub 2}. In layered bed PSA processes, the temperature variations inside the bed reflected a kind of inflection or plateau at which a roll-up phenomenon occurred and showed the dynamics of adsorption well at each step during a cycle. Simulated results of the dynamic model incorporating mass, energy and momentum balances agreed well with the PSA experimental results.

  4. Tip Growth Of Carbon Nanotubes Obtained By Pyrolyzation Of Camphor Oil With Zeolite Embedded With Fe/Ni/Mn Catalyst

    NASA Astrophysics Data System (ADS)

    Azira, A. A.; Zainal, N. F. A.; Nik, S. F.; Rusop, M.

    2009-06-01

    Highly efficient synthesis of carbon nanotubes (CNTs) have been synthesized by thermal decomposition of camphor oil, on a zeolite support impregnated with Fe/Ni/Mn (molar ratio of Fe:Ni:Mn = 1:1:1) catalyst in the temperature range from 550-950° C by the thermal CVD method. Besides the surface fluidization of the catalyst nanoparticles themselves, assistance of the metal oxides embedded in zeolite supports is supposed to be responsible for high activity and selectivity of the Fe/Ni/Mn catalyst over which carbon source (camphor oil) successfully decomposes. The CNT yield was higher at 850° C and can be considered as the optimum deposition temperature. This result demonstrates that zeolite impregnated with the catalyst Fe/Ni/Mn is a suitable support for effective formation of CNTs. The morphological studies support `tip growth mechanism' for the growth of the CNT's in our case. The as-grown CNTs were characterized by FESEM and FTIR spectroscopy.

  5. Catalyst Activity Comparison of Alcohols over Zeolites

    SciTech Connect

    Ramasamy, Karthikeyan K.; Wang, Yong

    2013-01-01

    Alcohol transformation to transportation fuel range hydrocarbon on HZSM-5 (SiO2 / Al2O3 = 30) catalyst was studied at 360oC and 300psig. Product distributions and catalyst life were compared using methanol, ethanol, 1-propanol or 1-butanol as a feed. The catalyst life for 1-propanol and 1-butanol was more than double compared to that for methanol and ethanol. For all the alcohols studied, the product distributions (classified to paraffin, olefin, napthene, aromatic and naphthalene compounds) varied with time on stream (TOS). At 24 hours TOS, liquid product from 1-propanol and 1-butanol transformation primarily contains higher olefin compounds. The alcohol transformation process to higher hydrocarbon involves a complex set of reaction pathways such as dehydration, oligomerization, dehydrocyclization, and hydrogenation. Compared to ethylene generated from methanol and ethanol, oligomerization of propylene and butylene has a lower activation energy and can readily take place on weaker acidic sites. On the other hand, dehydrocyclization of propylene and butylene to form the cyclic compounds requires the sits with stronger acid strength. Combination of the above mentioned reasons are the primary reasons for olefin rich product generated in the later stage of the time on stream and for the extended catalyst life time for 1 propanol and 1 butanol compared to methanol and ethanol conversion over HZSM-5.

  6. Krypton Adsorption on Zeolite-Templated Carbon and Anomalous Surface Thermodynamics.

    PubMed

    Murialdo, Maxwell; Stadie, Nicholas P; Ahn, Channing C; Fultz, Brent

    2015-07-28

    Krypton adsorption was measured at eight temperatures between 253 and 433 K on a zeolite-templated carbon and two commercial carbons. The data were fitted using a generalized Langmuir isotherm model and thermodynamic properties were extracted. Differing from that on commercial carbons, krypton adsorption on the zeolite-templated carbon is accompanied by an increasing isosteric enthalpy of adsorption, rising by up to 1.4 kJ mol(-1) as a function of coverage. This increase is a result of enhanced adsorbate-adsorbate interactions promoted by the ordered, nanostructured surface of the adsorbent. An assessment of the strength and nature of these adsorbate-adsorbate interactions is made by comparing the measured isosteric enthalpies of adsorption (and other thermodynamic quantities) to fundamental metrics of intermolecular interactions of krypton and other common gases. PMID:26136159

  7. Imprinted zeolite modified carbon paste electrode as a potentiometric sensor for uric acid

    NASA Astrophysics Data System (ADS)

    Khasanah, Miratul; Widati, Alfa Akustia; Fitri, Sarita Aulia

    2016-03-01

    Imprinted zeolite modified carbon paste electrode (carbon paste-IZ) has been developed and applied to determine uric acid by potentiometry. The imprinted zeolite (IZ) was synthesized by the mole ratio of uric acid/Si of 0.0306. The modified electrode was manufactured by mass ratio of carbon, IZ and solid paraffin was 40:25:35. The modified electrode had shown the measurement range of 10-5 M to 10-2 M with Nernst factor of 28.6 mV/decade, the detection limit of 5.86 × 10-6 M and the accuracy of 95.3 - 105.0%. Response time of the electrode for uric acid 10-5 M - 10-2 M was 25 - 44 s. The developed electrode showed the high selectivity toward uric acid in the urea matrix. Life time of the carbon paste-IZ electrode was 10 weeks.

  8. Enhanced Activity of Nanocrystalline Beta Zeolite for Acylation of Veratrole with Acetic Anhydride.

    PubMed

    Aisha Mahmood Abdulkareem, Al-Turkustani; Selvin, Rosilda

    2016-04-01

    Friedel-Craft acylation of veratrole using homogeneous acid catalysts such as AlCl3, FeCl3, ZnCl2, and HF etc. produces acetoveratrone, (3',4'-dimethoxyacetophenone), which is the intermediate for synthesis of papavarine alkaloids. The problems associated with these homogeneous catalysts can be overcome by using heterogeneous solid catalysts. Since acetoveratrone is a larger molecule, large pore Beta zeolites with smaller particle sizes are beneficial for the liquid-phase acylation of veratrole, for easy diffusion of reactants and products. The present study aims in the acylation of veratrole with acetic anhydride using nanocrystalline Beta Zeolite catalyst. A systematic investigation of the effects of various reaction parameters was done. The catalysts were characterized for their structural features by using XRD, TEM and DLS analyses. The catalytic activity of nanocrystalline Beta zeolite was compared with commercial Beta zeolite for the acylation and was found that nanocrystalline Beta zeolite possessed superior activity. PMID:27451793

  9. Enhanced photocatalytic activity of supported TiO2 by selective surface modification of zeolite Y

    NASA Astrophysics Data System (ADS)

    Guesh, Kiros; Márquez-Álvarez, Carlos; Chebude, Yonas; Díaz, Isabel

    2016-08-01

    Zeolite Y was treated using ammonium acetate and ammonium fluoride sequentially. As a consequence the aluminum from the surface was selectively removed. Then, loading with TiO2 (20 wt%) led to a final photocatalyst. The samples were characterized by X-ray diffraction (XRD), elemental analysis (ICP-OES), N2 adsorption, diffuse reflectance UV-vis spectroscopy (DRS), photoluminescence spectroscopy (PL), and X-ray photoelectron spectroscopy (XPS). It was found that 50% of the Al atoms were removed from the surface of the zeolite without affecting the framework structure. The TiO2/treated zeolite sample yielded 92% photocatalytic degradation of 10 ppm methyl orange (MO), a model pollutant, while the TiO2/parent zeolite converted only 7.6%. The mass normalized turnover rate (TORm) of the treated zeolite loaded with TiO2 was about 12 times higher than that of the parent zeolite loaded with the same amount of TiO2 precursor. This higher photocatalytic activity of the TiO2 supported on treated zeolite can be attributed to a more efficient interaction of the TiO2 with the zeolite leading to higher adsorption capacity. Reusability of the photocatalysts was assessed by performing three consecutive reaction cycles that showed no significant loss of photocatalytic activity.

  10. Decreased methane formation from the hydrogenation of carbon monoxide using zeolite/cobalt-manganese oxide composite catalysts.

    PubMed

    Johns, M; Landon, P; Alderson, T; Hutchings, G J

    2001-12-01

    A composite catalyst comprising a physical mixture of a zeolite and a cobalt/manganese oxide Fischer-Tropsch catalyst decreases the formation of methane in the hydrogenation of carbon monoxide without significantly affecting conversion. PMID:12240011

  11. Hierarchical Zeolites with Amine-Functionalized Mesoporous Domains for Carbon Dioxide Capture.

    PubMed

    Nguyen, Tien Hoa; Kim, Sungjune; Yoon, Minyoung; Bae, Tae-Hyun

    2016-03-01

    To prepare materials with high CO2 adsorption, a series of hierarchical LTA zeolites possessing various mesopore spaces that are decorated with alkylamines was designed and synthesized. The highest CO2 uptake capacity was achieved when (3-aminopropyl)trimethoxysilane (APTMS) was grafted onto the hierarchical LTA zeolite having the largest mesopores. Owing to the contributions of both alkylamine groups grafted onto the mesopore surfaces and active sites in the LTA zeolites, the amount of CO2 that can be taken up on these materials is much higher than for conventional aminosilicas such SBA-15 and MCM-41. Furthermore, the adsorbent shows good CO2 uptake capacity and recyclability in dynamic flow conditions. PMID:26833434

  12. Upgrading of coal-derived liquids. 1. Catalytic activities of zeolite catalysts and commercial HDS catalysts

    SciTech Connect

    Yoshida, R.; Hara, S.; Yoshida, T.; Yokoyama, S.; Nakata, Y.; Goto, Y.; Maekawa, Y.

    1983-01-01

    The applicability of various zeolite catalysts and commercial hydrodesulfurization (HDS) catalysts to the secondary hydrotreatment of coal-derived liquids was examined in relation to the chemical structure of upgraded liquids. The catalytic activities of zeolite catalysts for HI conversion is lower than are the activities of Ni-Mo, Ni-Co-Mo, Co-Mo and Ni-W catalysts. However, as regards hydrogenation and the removal of nitrogen, zeolite catalysts such as natural clinoptilolite and mordenite have almost the same activity as do Co-Mo and Ni-W catalysts. As to the removal of oxygen, it was proved that zeolite catalysts had a functionality to remove oxygen as CO/sub x/ gas, and HDS catalysts had a high activity for hydrodeoxygenation. 10 references, 3 figures, 4 tables.

  13. Carbon Dioxide Adsorption on a 5A Zeolite Designed for CO2 Removal in Spacecraft Cabins

    NASA Technical Reports Server (NTRS)

    Mulloth, Lila M.; Finn, John E.

    1998-01-01

    Carbon dioxide adsorption data were obtained for a 5A zeolite manufactured by AlliedSignal Inc. (Des Plaines, Illinois). The material is planned for use in the Carbon Dioxide Removal Assembly (CDRA) for U.S. elements of the International Space Station. The family of adsorption isotherms covers a temperature range of O to 250 C, and a pressure range of 0.001 to 800 torr. Coefficients of the Toth equation are fit to the data. Isosteric heats of adsorption are derived from the equilibrium loading data.

  14. Fabrication of zeolite/polymer multilayer composite membranes for carbon dioxide capture: Deposition of zeolite particles on polymer supports.

    PubMed

    Ramasubramanian, Kartik; Severance, Michael A; Dutta, Prabir K; Ho, W S Winston

    2015-08-15

    Membranes, due to their smaller footprint and potentially lower energy consumption than the amine process, offer a promising route for post-combustion CO2 capture. Zeolite Y based inorganic selective layers offer a favorable combination of CO2 permeance and CO2/N2 selectivity, membrane properties crucial to the economics. For economic viability on large scale, we propose to use flexible and scalable polymer supports for inorganic selective layers. The work described in this paper developed a detailed protocol for depositing thin zeolite Y seed layers on polymer supports, the first step in the synthesis of a polycrystalline zeolite Y membrane. We also studied the effects of support surface morphology (pore size and surface porosity) on the quality of deposition and identified favorable supports for the deposition. Two different zeolite Y particles with nominal sizes of 200 nm and 40 nm were investigated. To obtain a complete coverage of zeolite particles on the support surface with minimum defects and in a reproducible manner, a vacuum-assisted dip-coating technique was developed. Images obtained using both digital camera and optical microscope showed the presence of color patterns on the deposited surface which suggested that the coverage was complete. Electron microscopy revealed that the particle packing was dense with some drying cracks. Layer thickness with the larger zeolite Y particles was close to 1 μm while that with the smaller particles was reduced to less than 0.5 μm. In order to reduce drying cracks for layers with smaller zeolite Y particles, thickness was reduced by lowering the dispersion concentration. Transport measurement was used as an additional technique to characterize these layers. PMID:25950846

  15. Binderless thin films of zeolite-templated carbon electrodes useful for electrochemical microcapacitors with ultrahigh rate performance.

    PubMed

    Berenguer-Murcia, Ángel; Ruiz-Rosas, Ramiro R; García-Aguilar, Jaime; Nueangnoraj, Khanin; Nishihara, Hirotomo; Morallón, Emilia; Kyotani, Takashi; Cazorla-Amorós, Diego

    2013-07-01

    Controlled nanozeolite deposits are prepared by electrochemical techniques on a macroporous carbon support and binderless thin film electrodes of zeolite-templated carbon are synthesized using the deposits as templates. The obtained film electrodes exhibit extremely high area capacitance (10-12 mF cm(-2)) and ultrahigh rate capability in a thin film capacitor. PMID:23715380

  16. Curbing the greenhouse effect by carbon dioxide adsorption with zeolite 13X

    SciTech Connect

    Konduru, N.; Lindner, P.; Assaf-Anad, N.M.

    2007-12-15

    The removal of carbon dioxide (CO{sub 2}) from industrial emissions has become essential in the fight against climate change. In this study, we employed Zeolite 13X for the capture and recovery of CO{sub 2} in a flow through system where the adsorbent was subjected to five adsorption-desorption cycles. The influent stream contained 1.5% CO{sub 2} at standard conditions. The adsorbent bed was 1 in. in length and 1 in.3/8 in dia., and was packed with 10 g of the zeolite. Temperature swing adsorption (TSA) was employed as the regeneration method through heating to approximately 135{sup o}C with helium as the purge gas. The adsorbent capacity at 90% saturation was found to decrease from 78 to 60g CO{sub 2}/kg{sub Zeolite13X} after the fifth cycle. The CO{sub 2} capture ratio or the mass of CO{sub 2} adsorbed to the total mass that entered the system decreased from 63% to only 61% after the fifth cycle. The CO{sub 2} recovery efficiency ranged from 82 to 93% during desorption, and the CO{sub 2} relative recovery, i.e., CO{sub 2} desorbed for the nth cycle to CO{sub 2} adsorbed for the first cycle, ranged from 88 to 68%. The service life of the adsorbent was determined to be equal to eleven cycles at a useful capacity of 40g CO{sub 2}/kg{sub Zeolite13X}.

  17. Adsorption and photocatalytic degradation of pharmaceuticals and pesticides by carbon doped-TiO2 coated on zeolites under solar light irradiation.

    PubMed

    An, Ye; de Ridder, David Johannes; Zhao, Chun; Schoutteten, Klaas; Bussche, Julie Vanden; Zheng, Huaili; Chen, Gang; Vanhaecke, Lynn

    2016-01-01

    To evaluate the performance of zeolite-supported carbon-doped TiO(2) composite catalysts toward target pollutants under solar light irradiation, the adsorption and photocatalytic degradation of 18 pharmaceuticals and pesticides with distinguishing features (molecular size and volume, and photolysis) were investigated using mordenite zeolites with SiO(2)/Al(2)O(3) ratios of 18 and 240. Different quantities of carbon-doped TiO(2) were coated on the zeolites, and then the finished composite catalysts were tested in demineralized, surface, and hospital wastewater samples, respectively. The composite photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, and surface area and porosity analyses. Results showed that a dispersed layer of carbon-doped TiO(2) is formed on the zeolite surface; this layer blocks the micropores of zeolites and reduces their surface area. However, these reductions did not significantly affect adsorption onto the zeolites. Our results demonstrated that zeolite-supported carbon-doped TiO(2) systems can effectively degrade 18 pharmaceuticals and pesticides in demineralized water under natural and simulated solar light irradiation. In surface and hospital wastewaters, zeolite-supported carbon-doped TiO(2) systems present excellent anti-interference capability against radical scavengers and competitive organics for pollutants removal, and higher pollutants adsorption on zeolites evidently enhances the removal rate of target pollutants in surface and hospital wastewater samples with a complicated matrix. PMID:27332831

  18. Improved photocatalytic activity of zeolite- and silica-incorporated TiO2 film.

    PubMed

    Tanaka, K; Fukuyoshi, J; Segawa, H; Yoshida, K

    2006-09-21

    Porous TiO2 film was prepared by sol-gel method from TiO2 sol containing polyvinylpyrolidone (PVP). Photocatalytic activity of the film was evaluated by the elimination rate of ethylene. Several adsorbents including zeolite and silica powders were incorporated into the TiO2 film. All the adsorbents enhanced the activity. The optimum adsorbent content was 0.005-0.01 g/ml of the coating sol solution. Silica provided better activity than zeolite. At high humidity and in dry air the activity decreased. PMID:16704899

  19. Enhanced Activity of Nanocrystalline Zeolites for Selective Catalytic Reduction of NOx

    SciTech Connect

    Sarah C. Larson; Vicki H. Grassian

    2006-12-31

    Nanocrystalline zeolites with discrete crystal sizes of less than 100 nm have different properties relative to zeolites with larger crystal sizes. Nanocrystalline zeolites have improved mass transfer properties and very large internal and external surface areas that can be exploited for many different applications. The additional external surface active sites and the improved mass transfer properties of nanocrystalline zeolites offer significant advantages for selective catalytic reduction (SCR) catalysis with ammonia as a reductant in coal-fired power plants relative to current zeolite based SCR catalysts. Nanocrystalline NaY was synthesized with a crystal size of 15-20 nm and was thoroughly characterized using x-ray diffraction, electron paramagnetic resonance spectroscopy, nitrogen adsorption isotherms and Fourier Transform Infrared (FT-IR) spectroscopy. Copper ions were exchanged into nanocrystalline NaY to increase the catalytic activity. The reactions of nitrogen dioxides (NO{sub x}) and ammonia (NH{sub 3}) on nanocrystalline NaY and CuY were investigated using FT-IR spectroscopy. Significant conversion of NO{sub 2} was observed at room temperature in the presence of NH{sub 3} as monitored by FT-IR spectroscopy. Copper-exchanged nanocrystalline NaY was more active for NO{sub 2} reduction with NH{sub 3} relative to nanocrystalline NaY.

  20. Amine-functionalized, silver-exchanged zeolite NaY: Preparation, characterization and antibacterial activity

    NASA Astrophysics Data System (ADS)

    Hanim, Siti Aishah Mohd; Malek, Nik Ahmad Nizam Nik; Ibrahim, Zaharah

    2016-01-01

    Amine-functionalized, silver-exchanged zeolite NaY (ZSA) were prepared with three different concentrations of 3-aminopropyltriethoxysilane (APTES) (0.01, 0.20 and 0.40 M) and four different concentrations of silver ions (25%, 50%, 100% and 200% from zeolite cation exchange capacity (CEC)). The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), surface area analysis, thermogravimetric analysis (TGA) and zeta potential (ZP) analysis. The FTIR results indicated that the zeolite was functionalized by APTES and that the intensity of the peaks corresponding to APTES increased as the concentration of APTES used was increased. The antibacterial activities of the silver-exchanged zeolite NaY (ZS) and ZSA were studied against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538 using the disc diffusion technique (DDT) and minimum inhibitory concentration (MIC). The antibacterial activity of ZSA increased with the increase in APTES on ZS, and E. coli was more susceptible towards the sample compared to S. aureus. The FESEM micrographs of the bacteria after contact with the ZSA suggested different mechanisms of bacterial death for these two bacteria due to exposure to the studied sample. The functionalization of ZS with APTES improved the antibacterial activity of the silver-zeolite, depending on the concentration of silver ions and APTES used during modification.

  1. Reversible emission evolution from Ag activated zeolite Na-A upon dehydration/hydration

    SciTech Connect

    Lin, Hui E-mail: fujii@eedept.kobe-u.ac.jp; Imakita, Kenji; Fujii, Minoru E-mail: fujii@eedept.kobe-u.ac.jp

    2014-11-24

    Reversible emission evolution of thermally treated Ag activated zeolite Na-A upon dehydration/hydration in vacuum/water vapor was observed. The phenomenon was observed even for the sample with low Ag{sup +}-Na{sup +} exchanging (8.3%), indicating that the emission from Ag activated zeolites may not come from Ag clusters while from the surrounding coordinated Ag{sup +} ions or Ag{sup 0} atoms. It was disclosed that the characteristic yellow-green emission at ∼560 ± 15 nm is strongly associated with the coordinating water molecules to the Ag{sup +} ions or Ag{sup 0} atoms, which is clear evidence for that the efficient emission from Ag activated zeolites may not originate from the quantum confinement effect.

  2. Fossilized microorganisms associated with zeolite-carbonate interfaces in sub-seafloor hydrothermal environments.

    PubMed

    Ivarsson, M; Lindblom, S; Broman, C; Holm, N G

    2008-03-01

    In this paper we describe carbon-rich filamentous structures observed in association with the zeolite mineral phillipsite from sub-seafloor samples drilled and collected during the Ocean Drilling Program (ODP) Leg 197 at the Emperor Seamounts. The filamentous structures are approximately 5 microm thick and approximately 100-200 microm in length. They are found attached to phillipsite surfaces in veins and entombed in vein-filling carbonates. The carbon content of the filaments ranges between approximately 10 wt% C and 55 wt% C. They further bind to propidium iodide (PI), which is a dye that binds to damaged cell membranes and remnants of DNA. Carbon-rich globular microstructures, 1-2 microm in diameter, are also found associated with the phillipsite surfaces as well as within wedge-shaped cavities in phillipsite assemblages. The globules have a carbon content that range between approximately 5 wt% C and 55 wt% C and they bind to PI. Ordinary globular iron oxides found throughout the samples differ in that they contain no carbon and do not bind to the dye PI. The carbon-rich globules are mostly concentrated to a film-like structure that is attached to the phillipsite surfaces. This film has a carbon content that ranges between approximately 25 wt% C and 75 wt% C and partially binds to PI. EDS analyses show that the carbon in all structures described are not associated with calcium and therefore not bound in carbonates. The carbon content and the binding to PI may indicate that the filamentous structures could represent fossilized filamentous microorganisms, the globules could represent fossilized microbial cells and the film-like structures could represent a microbially produced biofilm. Our results extend the knowledge of possible habitable niches for a deep biosphere in sub-seafloor environments and suggests, as phillipsite is one of the most common zeolite mineral in volcanic rocks of the oceanic crust, that it could be a common feature in the oceanic crust

  3. Synthesis, characterization and catalytic activity of indium substituted nanocrystalline Mobil Five (MFI) zeolite

    SciTech Connect

    Shah, Kishor Kr.; Nandi, Mithun; Talukdar, Anup K.

    2015-06-15

    Highlights: • In situ modification of the MFI zeolite by incorporation of indium. • The samples were characterized by XRD, FTIR, TGA, UV–vis (DRS), SAA, EDX and SEM. • The incorporation of indium was confirmed by XRD, FT-IR, UV–vis (DRS), EDX and TGA. • Hydroxylation of phenol reaction was studied on the synthesized catalysts. - Abstract: A series of indium doped Mobil Five (MFI) zeolite were synthesized hydrothermally with silicon to aluminium and indium molar ratio of 100 and with aluminium to indium molar ratios of 1:1, 2:1 and 3:1. The MFI zeolite phase was identified by XRD and FT-IR analysis. In XRD analysis the prominent peaks were observed at 2θ values of around 6.5° and 23° with a few additional shoulder peaks in case of all the indium incorporated samples suggesting formation of pure phase of the MFI zeolite. All the samples under the present investigation were found to exhibit high crystallinity (∼92%). The crystallite sizes of the samples were found to vary from about 49 to 55 nm. IR results confirmed the formation of MFI zeolite in all cases showing distinct absorbance bands near 1080, 790, 540, 450 and 990 cm{sup −1}. TG analysis of In-MFI zeolites showed mass losses in three different steps which are attributed to the loss due to adsorbed water molecules and the two types TPA{sup +} cations. Further, the UV–vis (DRS) studies reflected the position of the indium metal in the zeolite framework. Surface area analysis of the synthesized samples was carried out to characterize the synthesized samples The analysis showed that the specific surface area ranged from ∼357 to ∼361 m{sup 2} g{sup −1} and the pore volume of the synthesized samples ranged from 0.177 to 0.182 cm{sup 3} g{sup −1}. The scanning electron microscopy studies showed the structure of the samples to be rectangular and twinned rectangular shaped. The EDX analysis was carried out for confirmation of Si, Al and In in zeolite frame work. The catalytic activities of

  4. HYDROGENATION OF POLYCYCLIC AROMATIC COMPOUNDS USING NI SUPPORT ON H-BETA ZEOLITE IN SUPERCRITICAL CARBON DIOXIDE

    EPA Science Inventory

    The primary rationale for use of supercritical carbon dioxide as a solvent in hydrogenation is the elimination of mass transfer limitations, through enhancement of the solubility of hydrogen at the reaction locus. Hydrogenation of anthracene was performed using NiHB-zeolite catal...

  5. Activated zeolite--suitable carriers for microorganisms in anaerobic digestion processes?

    PubMed

    Weiß, S; Lebuhn, M; Andrade, D; Zankel, A; Cardinale, M; Birner-Gruenberger, R; Somitsch, W; Ueberbacher, B J; Guebitz, G M

    2013-04-01

    Plant cell wall structures represent a barrier in the biodegradation process to produce biogas for combustion and energy production. Consequently, approaches concerning a more efficient de-polymerisation of cellulose and hemicellulose to monomeric sugars are required. Here, we show that natural activated zeolites (i.e. trace metal activated zeolites) represent eminently suitable mineral microhabitats and potential carriers for immobilisation of microorganisms responsible for anaerobic hydrolysis of biopolymers stabilising related bacterial and methanogenic communities. A strategy for comprehensive analysis of immobilised anaerobic populations was developed that includes the visualisation of biofilm formation via scanning electron microscopy and confocal laser scanning microscopy, community and fingerprint analysis as well as enzyme activity and identification analyses. Using SDS polyacrylamide gel electrophoresis, hydrolytical active protein bands were traced by congo red staining. Liquid chromatography/mass spectroscopy revealed cellulolytical endo- and exoglucanase (exocellobiohydrolase) as well as hemicellulolytical xylanase/mannase after proteolytic digestion. Relations to hydrolytic/fermentative zeolite colonisers were obtained by using single-strand conformation polymorphism analysis (SSCP) based on amplification of bacterial and archaeal 16S rRNA fragments. Thereby, dominant colonisers were affiliated to the genera Clostridium, Pseudomonas and Methanoculleus. The specific immobilisation on natural zeolites with functional microbes already colonising naturally during the fermentation offers a strategy to systematically supply the biogas formation process responsive to population dynamics and process requirements. PMID:23435898

  6. Effect of zinc oxide amounts on the properties and antibacterial activities of zeolite/zinc oxide nanocomposite.

    PubMed

    Alswat, Abdullah A; Ahmad, Mansor Bin; Saleh, Tawfik A; Hussein, Mohd Zobir Bin; Ibrahim, Nor Azowa

    2016-11-01

    Nanocomposites of zinc oxide loaded on a zeolite (Zeolite/ZnO NCs) were prepared using co-precipitation method. The ratio effect of ZnO wt.% to the Zeolite on the antibacterial activities was investigated. Various techniques were used for the nanocomposite characterization, including UV-vis, FTIR, XRD, EDX, FESEM and TEM. XRD patterns showed that ZnO peak intensity increased while the intensities of Zeolite peaks decreased. TEM images indicated a good distribution of ZnO-NPs onto the Zeolite framework and the cubic structure of the zeolite was maintained. The average particle size of ZnO-nanoparticles loaded on the surface of the Zeolite was in the range of 1-10nm. Moreover, Zeolite/ZnO NCs showed noticeable antibacterial activities against the tested bacteria; Gram- positive and Gram- negative bacteria, under normal light. The efficiency of the antibacterial increased with increasing the wt.% from 3 to 8 of ZnO NPs, and it reached 87% against Escherichia coli E266. PMID:27524047

  7. A zeolite modified carbon paste electrode as useful sensor for voltammetric determination of acetaminophen.

    PubMed

    Ahmadpour-Mobarakeh, Leila; Nezamzadeh-Ejhieh, Alireza

    2015-04-01

    The voltammetric behavior of a carbon paste electrode modified with Co(II)-exchanged zeolite A (Co(II)-A/ZMCPE) for determination of acetaminophen was studied. The proposed electrode showed a diffusion controlled reaction with the electron transfer rate constant (Ks) of 0.44s(-1) and charge transfer coefficient of 0.73 in the absence of acetaminophen. A linear voltammetric response was obtained in the range of 0.1 to 190μmolL(-1) of acetaminophen [r(2)=0.9979, r=0.9989 (n=10)] with a detection limit of 0.04μmolL(-1). The method was successfully applied to the analysis of acetaminophen in some drugs. PMID:25686976

  8. 1D Superconducting behavior in 4-Angstrom carbon nanotube-zeolite composite

    NASA Astrophysics Data System (ADS)

    Shi, Wu; Wang, Zhe; Xie, Hang; Zhang, Ting; Wang, Ning; Tang, Zikang; Zhang, Xixiang; Lortz, Rolf; Sheng, Ping

    2010-03-01

    We report 4-probe electrical measurements on a sample of 4-Angstrom carbon nanotubes-zeolite composite that exhibit 1D superconducting behavior. The resistance displays a smooth decrease as a function of temperature that is characteristic of the phase slip fluctuation effects, and the differential resistance measured as a function of current shows a quasigap that is characteristic of the fluctuating condensate. Both data sets show very little variation upon the application of a magnetic field, up to 9 Tesla. These behaviors are explainable in terms of the Langer-Ambegaokar-McCumber-Halperin (LAMH) theory of phase slips. We also show and discuss an interesting phenomenon in which a sharp zero current (bias) peak appears in the differential resistance above 3 K.

  9. Zeolite scaffolds for cultures of human breast cancer cells. Part II: Effect of pure and hybrid zeolite membranes on neoplastic and metastatic activity control.

    PubMed

    Tavolaro, Palmira; Martino, Guglielmo; Andò, Sebastiano; Tavolaro, Adalgisa

    2016-11-01

    This work is focused on the response of two invasive phenotypes of human breast cancer cells, MCF-7 and MDA-MB-231, grown on synthesized zeolite scaffolds in order to study the influence of those biomaterials in controlled conditions with and without anti-tumoral drug treatments. Our research was directed to the use of doxorubicin (DOX) and bergapten (5-MOP). The former is broadly considered the most active single agent available for the treatment of breast cancer, the second is a natural psoralen with an apoptotic effect. The results indicate that both drugs inhibit the cell viability of all cell lines grown on all zeolite scaffolds and that all Pure Zeolite Membranes are more responsive with respect to all Mixed Matrix Membranes. Moreover, the results after treatment with DOX at a concentration of 7.4μM for 24h, show that the expression of the matrix metalloproteinases (MMP-2 and MMP-9) is greatly reduced in both cell lines, especially in those adherent on Pure Zeolite Scaffolds. PMID:27524044

  10. Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

    PubMed Central

    Žilková, Naděžda; Kubů, Martin; Mazur, Michal; Bastl, Zdeněk; Čejka, Jiří

    2015-01-01

    Summary Hoveyda–Grubbs type catalysts with cationic tags on NHC ligands were linker-free immobilized on the surface of lamellar zeolitic supports (MCM-22, MCM-56, MCM-36) and on mesoporous molecular sieves SBA-15. The activity of prepared hybrid catalysts was tested in olefin metathesis reactions: the activity in ring-closing metathesis of citronellene and N,N-diallyltrifluoroacetamide decreased in the order of support MCM-22 ≈ MCM-56 > SBA-15 > MCM-36; the hybrid catalyst based on SBA-15 was found the most active in self-metathesis of methyl oleate. All catalysts were reusable and exhibited low Ru leaching (<1% of Ru content). XPS analysis revealed that during immobilization ion exchange between Hoveyda–Grubbs type catalyst and zeolitic support occurred in the case of Cl− counter anion; in contrast, PF6 − counter anion underwent partial decomposition. PMID:26664629

  11. Transition Metal Ions in Zeolites: Coordination and activation of O2

    PubMed Central

    Smeets, Pieter J.; Woertink, Julia S.; Sels, Bert F.; Solomon, Edward I.; Schoonheydt, Robert A.

    2010-01-01

    Zeolites containing transition metal ions (TMI) often show promising activity as heterogeneous catalysts in pollution abatement and selective oxidation reactions. In this paper, two aspects of research on the TMI Cu, Co and Fe in zeolites are discussed: (i) coordination to the lattice and (ii) activated oxygen species. At low loading, TMI preferably occupy exchange sites in six-membered oxygen rings (6MR) where the TMI preferentially coordinate with the oxygen atoms of Al tetrahedra. High TMI loadings result in a variety of TMI species formed at the zeolite surface. Removal of the extra-lattice oxygens during high temperature pretreatments can result in auto-reduction. Oxidation of reduced TMI sites often results in the formation of highly reactive oxygen species. In Cu-ZSM-5, calcination with O2 results in the formation of a species, which was found to be a crucial intermediate in both the direct decomposition of NO and N2O and the selective oxidation of methane into methanol. An activated oxygen species, called α-oxygen, is formed in Fe-ZSM5 and reported to be the active site in the partial oxidation of methane and benzene into methanol and phenol, respectively. However, this reactive α-oxygen can only be formed with N2O, not with O2. O2 activated Co intermediates in Faujasite (FAU) zeolites can selectively oxidize α-pinene and epoxidize styrene. In Co-FAU, CoIII superoxo and peroxo complexes are suggested to be the active cores, whereas in Cu and Fe-ZSM-5 various monomeric and dimeric sites have been proposed, but no consensus has been obtained. Very recently, the active site in Cu-ZSM-5 was identified as a bent [Cu-O-Cu]2+ core (Proc. Natl. Acad. Sci. USA 2009, 106, 18908-18913). Overall, O2 activation depends on the interplay of structural factors such as type of zeolite, size of the channels and cages and chemical factors such as Si/Al ratio and the nature, charge and distribution of the charge balancing cations. The presence of several different TMI sites

  12. Activity diagrams for clinoptilolite: Susceptibility of this zeolite to further diagenetic reactions

    SciTech Connect

    Bowers, T.S.; Burns, R.G.

    1990-05-01

    Clinoptilolite is the predominant zeolite in diagenetically altered volcanic rocks at Yucca Mountain, Nevada, having formed by posteruptive reactions of ground water with vitric tuffs in the pyroclastic deposits. Compositional variations of clinoptilolites in the fractured and zeolitized tuffs not presently in contact with ground water and the vulnerability of zeolites to burial diagenesis raise questions about the long-term stability of clinoptilolite. Equilibrium activity diagrams were calculated for clinoptilolite solid solutions in the seven-component system Ca-Na-K-Mg-Fe-Al-Si plus H{sub 2}O, employing available thermodynamic data for related minerals, aqueous species, and water. Stability fields are portrayed graphically, assuming the presence of potassium feldspar, saponite, and hematite, and using ranges of activities for SiO{sub 2} and Al{sup 3+} defined by the saturation limits for several silica polymorphs, gibbsite, kaolinite, and pyrophyllite. The clinoptilolite stability field broadens with increasing atomic substitution of Ca for Na, and K for Ca, reaches a maximum for intermediate activities of dissolved Al, and decreases with increasing temperature. The thermodynamic calculations show that ground water of the sodium-bicarbonate type is approximately in equilibrium at 25C with calcite and several zeolites, including heulandite and calcic clinoptilolite. Mg-rich clinoptilolites are stabilized in ground water depleted in Ca{sup 2+}. The activity diagrams indicate that prolonged diagenetic reactions with ground water depleted in Al, enriched in Na or Ca, and heated by the thermal envelope surrounding buried nuclear waste may eliminate sorptive calcic clinoptilolites in fractured tuffs and underlying basal vitrophyre.

  13. Activated carbon from biomass

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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).

  14. Synthesis, characterization and catalytic activity of a novel mesoporous ZSM-5 zeolite

    SciTech Connect

    Ma, Yuanyuan; Hu, Jing; Jia, Lihua; Li, Zhifang; Kan, Qiubin; Wu, Shujie

    2013-05-15

    Highlights: ► Mesoporous ZSM-5 zeolites. ► The strong acidic intensity. ► High activity for the alkylation of phenol and tert-butyl alcohol. ► Remarkable hydrothermal stability. - Abstract: A novel mesoporous ZSM-5 zeolite was hydrothermally synthesized using glucose as a template. Characterizations by XRD, TEM and nitrogen isotherms indicated that ZSM-5 possessed worm-like mesoporous. {sup 27}Al-MAS-NMR and NH{sub 3}-TPD showed that the mesoporous ZSM-5 preserved tetrahedral coordination aluminum and stronger acidity than conventional mesoporous material. As-prepared mesoporous ZSM-5 was successfully used in alkylation reaction of phenol with tert-butanol and exhibited significantly high phenol conversion and 2,4-DTBP selectivity. In addition, the hydrothermal stability was also studied by boiling in water for 7 days and displayed good results.

  15. Sn-Beta zeolites with borate salts catalyse the epimerization of carbohydrates via an intramolecular carbon shift

    PubMed Central

    Gunther, William R.; Wang, Yuran; Ji, Yuewei; Michaelis, Vladimir K.; Hunt, Sean T.; Griffin, Robert G.; Román-Leshkov, Yuriy

    2012-01-01

    Carbohydrate epimerization is an essential technology for the widespread production of rare sugars. In contrast to other enzymes, most epimerases are only active on sugars substituted with phosphate or nucleotide groups, thus drastically restricting their use. Here we show that Sn-Beta zeolite in the presence of sodium tetraborate catalyses the selective epimerization of aldoses in aqueous media. Specifically, a 5 wt% aldose (for example, glucose, xylose or arabinose) solution with a 4:1 aldose:sodium tetraborate molar ratio reacted with catalytic amounts of Sn-Beta yields near-equilibrium epimerization product distributions. The reaction proceeds by way of a 1,2 carbon shift wherein the bond between C-2 and C-3 is cleaved and a new bond between C-1 and C-3 is formed, with C-1 moving to the C-2 position with an inverted configuration. This work provides a general method of performing carbohydrate epimerizations that surmounts the main disadvantages of current enzymatic and inorganic processes. PMID:23047667

  16. Potential and actual uses of zeolites in crop protection.

    PubMed

    De Smedt, Caroline; Someus, Edward; Spanoghe, Pieter

    2015-10-01

    In this review, it is demonstrated that zeolites have a potential to be used as crop protection agents. Similarly to kaolin, zeolites can be applied as particle films against pests and diseases. Their honeycomb framework, together with their carbon dioxide sorption capacity and their heat stress reduction capacity, makes them suitable as a leaf coating product. Furthermore, their water sorption capacity and their smaller particle sizes make them effective against fungal diseases and insect pests. Finally, these properties also ensure that zeolites can act as carriers of different active substances, which makes it possible to use zeolites for slow-release applications. Based on the literature, a general overview is provided of the different basic properties of zeolites as promising products in crop protection. PMID:25727795

  17. ZSM-5 zeolite nanosheets with improved catalytic activity synthesized using a new class of structure-directing agents.

    PubMed

    Kore, Rajkumar; Srivastava, Rajendra; Satpati, Biswarup

    2014-09-01

    A new series of multiquaternary ammonium structure-directing agents, based on 1,4-diazabicyclo[2.2.2]octane, was prepared. ZSM-5 zeolites with nanosheet morphology (10 nm crystal thickness) were synthesized under hydrothermal conditions using multiquaternary ammonium surfactants as the zeolite structure-generating agents. Both wide-angle and small-angle diffraction patterns were obtained using only a suitable structure-directing agent under a specific zeolite synthesis composition. A mechanism of zeolite formation is proposed based on the results obtained from various physicochemical characterizations. ZSM-5 materials were investigated in catalytic reactions requiring medium to strong acidity, which are important for the synthesis of a wide range of industrially important fine and specialty chemicals. The catalytic activity of ZSM-5 materials was compared with that of the conventional ZSM-5 and amorphous mesoporous aluminosilicate Al-MCM-41. The synthesis strategy of the present investigation using the new series of structure-directing agents could be extended for the synthesis of other related zeolites or other porous materials in the future. Zeolite with a structural feature as small as the size of a unit cell (5-10 nm) with hierarchically ordered porous structure would be very promising for catalysis. PMID:25056112

  18. Osmium(0) nanoclusters stabilized by zeolite framework; highly active catalyst in the aerobic oxidation of alcohols under mild conditions.

    PubMed

    Zahmakiran, Mehmet; Akbayrak, Serdar; Kodaira, Tetsuya; Ozkar, Saim

    2010-08-28

    Osmium(0) nanoclusters stabilized by zeolite-Y framework were reproducibly prepared by a simple two step procedure involving the incorporation of osmium(III) cations into the zeolite matrix by ion-exchange, followed by their reduction within the cavities of zeolite with sodium borohydride in aqueous solution all at room temperature. The composition and morphology of osmium(0) nanoclusters stabilized by zeolite framework, as well as the integrity and crystallinity of the host material were investigated by using ICP-OES, XRD, XPS, SEM, TEM, HRTEM, TEM/EDX, mid-IR, far-IR spectroscopies, and N(2)-adsorption/desorption technique. The results of the multiprong analysis reveal the formation of osmium(0) nanoclusters within the cavities of zeolite-Y without causing alteration in the framework lattice, formation of mesopores, or loss in the crystallinity of the host material. More importantly, far-IR studies showed that after the reduction of Os(3+) cations by sodium borohydride the Na(+) cations reoccupy their authentic cation sites restoring the integrity of zeolite-Y. The catalytic activity of osmium(0) nanoclusters stabilized by zeolite framework was tested in the aerobic oxidation of activated, unactivated and heteroatom containing alcohols to carbonyl compounds and was found to provide high activity and selectivity even under mild conditions (80 degrees C and 1 atm O(2) or air). Moreover, they were found to be stable enough to be isolated and bottled as solid material, which can be reused as active catalyst under the identical conditions of the first run. PMID:20614055

  19. Large surface area ordered porous carbons via nanocasting zeolite 10X and high performance for hydrogen storage application.

    PubMed

    Cai, Jinjun; Li, Liangjun; Lv, Xiaoxia; Yang, Chunpeng; Zhao, Xuebo

    2014-01-01

    We report the preparation of ordered porous carbons for the first time via nanocasting zeolite 10X with an aim to evaluate their potential application for hydrogen storage. The synthesized carbons exhibit large Brunauer-Emmett-Teller surface areas in the 1300-3331 m(2)/g range and pore volumes up to 1.94 cm(3)/g with a pore size centered at 1.2 nm. The effects of different synthesis processes with pyrolysis temperature varied in the 600-800 °C range on the surface areas, and pore structures of carbons were explored. During the carbonization process, carbons derived from the liquid-gas two-step routes at around 700 °C are nongraphitic and retain the particle morphology of 10X zeolite, whereas the higher pyrolysis temperature results in some graphitic domains and hollow-shell morphologies. In contrast, carbons derived from the direct acetylene infiltration process have some incident nanoribbon or nanofiber morphologies. A considerable hydrogen storage capacity of 6.1 wt % at 77 K and 20 bar was attained for the carbon with the surface area up to 3331 m(2)/g, one of the top-ranked capacities ever observed for large surface area adsorbents, demonstrating their potential uses for compacting gaseous fuels of hydrogen. The hydrogen capacity is comparable to those of previously reported values on other kinds of carbon-based materials and highly dependent on the surface area and micropore volume of carbons related to the optimum pore size, therefore providing guidance for the further search of nanoporous materials for hydrogen storage. PMID:24344972

  20. Activated carbon material

    DOEpatents

    Evans, A. Gary

    1978-01-01

    Activated carbon particles for use as iodine trapping material are impregnated with a mixture of selected iodine and potassium compounds to improve the iodine retention properties of the carbon. The I/K ratio is maintained at less than about 1 and the pH is maintained at above about 8.0. The iodine retention of activated carbon previously treated with or coimpregnated with triethylenediamine can also be improved by this technique. Suitable flame retardants can be added to raise the ignition temperature of the carbon to acceptable standards.

  1. Tin-containing zeolites are highly active catalysts for the isomerization of glucose in water

    SciTech Connect

    Moliner, Manuel; Roman-Leshkov, Yuriy; Davis, Mark E.

    2010-04-06

    The isomerization of glucose into fructose is a large-scale reaction for the production of high-fructose corn syrup (HFCS; reaction performed by enzyme catalysts) and recently is being considered as an intermediate step in the possible route of biomass to fuels and chemicals. Here, it is shown that a large-pore zeolite that contains tin (Sn-Beta) is able to isomerize glucose to fructose in aqueous media with high activity and selectivity. Specifically, a 10% (wt/wt) glucose solution containing a catalytic amount of Sn-Beta (1:50 Sn:glucose molar ratio) gives product yields of approximately 46% (wt/wt) glucose, 31% (wt/wt) fructose, and 9% (wt/wt) mannose after 30 min and 12 min of reaction at 383 K and 413 K, respectively. This reactivity is achieved also when a 45 wt% glucose solution is used. The properties of the large-pore zeolite greatly influence the reaction behavior because the reaction does not proceed with a medium-pore zeolite, and the isomerization activity is considerably lower when the metal centers are incorporated in ordered mesoporous silica (MCM-41). The Sn-Beta catalyst can be used for multiple cycles, and the reaction stops when the solid is removed, clearly indicating that the catalysis is occurring heterogeneously. Most importantly, the Sn-Beta catalyst is able to perform the isomerization reaction in highly acidic, aqueous environments with equivalent activity and product distribution as in media without added acid. This enables Sn-Beta to couple isomerizations with other acid-catalyzed reactions, including hydrolysis/isomerization or isomerization/dehydration reaction sequences [starch to fructose and glucose to 5-hydroxymethylfurfural (HMF) demonstrated here].

  2. Spectroscopic and XRD characterisation of zeolite catalysts active for the oxidative methylation of benzene with methane

    NASA Astrophysics Data System (ADS)

    Adebajo, Moses O.; Long, Mervyn A.; Frost, Ray L.

    2004-03-01

    The benzene methylation with methane over zeolite catalysts was previously shown in our laboratory to require the presence of oxygen. Thus, a two-step mechanism involving the intermediate formation of methanol by partial oxidation of methane followed by the methylation of benzene with methanol in the second step, was postulated. This paper now reports the results of the characterisation of the zeolite catalysts used for the oxidative benzene methylation reaction in order to provide some information about their composition, structure, properties and their behaviour before and after the reaction. The catalysts were characterised by X-ray diffraction (XRD), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray fluorescence (XRF), FT-IR and solid state NMR. XRD results indicate that the crystalline structures of all the ZSM-5 and H-beta catalysts remained unchanged after batch reaction of benzene with methane over the catalysts in agreement with the observation that the catalysts recovered from the reactor could be reused without loss of activity. Elemental analyses and FT-IR data show that as the level of metal ion exchange increases, the Brönsted acid concentration decreases but this metal ion exchange does not totally remove Brönsted acidity. FT-IR results further show that only a small amount of acid sites is actually necessary for a catalyst to be active since used catalysts containing highly reduced Brönsted acidity are found to be reusable without any loss of their activity. 29Si and 27Al magic angle spinning (MAS) NMR together with FT-IR spectra also show that all the active zeolites catalysts contain some extra-framework octahedral aluminium in addition to the normal tetrahedral framework aluminium. The presence of this extra-lattice aluminium does not, however, have any adverse effect on the crystallinity of the catalysts both before and after oxidative benzene methylation reaction. There appears also to be no significant dealumination

  3. Carbon-13 NMR spectroscopy study of L-zeolite- and silica-supported platinum catalysts

    SciTech Connect

    Sharma, S.B.; Laska, T.E.; Balaraman, P.; Root, T.W.; Dumesic, J.A.

    1994-12-01

    NMR studies of CO adsorbed on small Pt particles show evidence of changes in the metallic nature of these particles with size. Large particles on silica or the exterior of zeolite crystallites have conduction-band electrons that cause a Knight shift for adsorbed CO. Small particles in zeolite cavities are diamagnetic clusters, and yield spectra for linear and bridging carbonyls similar to those of transition-metal cluster compounds. {sup 13}C NMR of CO offers a simple probe of metal dispersion and particle size for these Pt catalysts and other noble metal systems. 29 refs., 7 figs., 2 tabs.

  4. CuO nanoparticles incorporated in hierarchical MFI zeolite as highly active electrocatalyst for non-enzymatic glucose sensing.

    PubMed

    Dong, Junping; Tian, Taolei; Ren, Linxiao; Zhang, Yuan; Xu, Jiaqiang; Cheng, Xiaowei

    2015-01-01

    A hierarchical MFI zeolite, with typical micro/meso bimodal pore structures, was prepared by desilication method. CuO nanoparticles (NPs) were incorporated into the hierarchical MFI zeolite by impregnation method. CuO/hierarchical zeolite composites were characterized by X-ray diffraction, transmission electron microscopy and nitrogen sorption. It is shown that the CuO nanoparticles are mostly dispersed in the mesopores with remaining of the crystallinity and morphology of the host zeolite. CuO nanoparticles located in hierarchical zeolite exhibit the excellent electrocatalytic performances to oxidation of glucose in alkaline media. The electrocatalytic activity enhances with increasing the loading content of CuO from 5% to 15%. The composites were fabricated for nonenzyme glucose sensing. Under the optimal conditions, the sensor shows a wide linear range from 5×10(-7) to 1.84×10(-2) M with a low detection limit of 3.7×10(-7) M. The sensor also exhibits good repeatability, long-term stability as well as high selectivity against interfering species. PMID:25499226

  5. Antimicrobial Activity of Silver Ions Released from Zeolites Immobilized on Cellulose Nanofiber Mats.

    PubMed

    Rieger, Katrina A; Cho, Hong Je; Yeung, Hiu Fai; Fan, Wei; Schiffman, Jessica D

    2016-02-10

    In this study, we exploit the high silver ion exchange capability of Linde Type A (LTA) zeolites and present, for the first time, electrospun nanofiber mats decorated with in-house synthesized silver (Ag(+)) ion exchanged zeolites that function as molecular delivery vehicles. LTA-Large zeolites with a particle size of 6.0 μm were grown on the surface of the cellulose nanofiber mats, whereas LTA-Small zeolites (0.2 μm) and three-dimensionally ordered mesoporous-imprinted (LTA-Meso) zeolites (0.5 μm) were attached to the surface of the cellulose nanofiber mats postsynthesis. After the three zeolite/nanofiber mat assemblies were ion-exchanged with Ag(+) ions, their ion release profiles and ability to inactivate Escherichia coli (E. coli) K12 were evaluated as a function of time. LTA-Large zeolites immobilized on the nanofiber mats displayed more than an 11 times greater E. coli K12 inactivation than the Ag-LTA-Large zeolites that were not immobilized on the nanofiber mats. This study demonstrates that by decorating nanometer to micrometer scale Ag(+) ion-exchanged zeolites on the surface of high porosity, hydrophilic cellulose nanofiber mats, we can achieve a tunable release of Ag(+) ions that inactivate bacteria faster and are more practical to use in applications over powder zeolites. PMID:26788882

  6. Adsorption of carbon monoxide on ZSM-5 zeolites. Infrared spectroscopic study and quantum-chemical calculations

    SciTech Connect

    Kustov, L.M.; Kazansky, V.B.; Beran, S.; Kubelkova, L.; Jiru, P.

    1987-09-24

    Low temperature adsorption of CO was studied on H-ZSM-5 zeolites modified by dehydroxylation, ionic exchange with Al/sup 3 +/, and impregnation with Al/sub 2/O/sub 3/ and on Na-ZSM-5 and CaH-ZSM-5 zeolites. It was found that interaction of CO with framework OH groups results in the formation of a hydrogen-bonded CO complex whose OH bond frequency is decreased by 310-320 cm/sup -1/ compared with that of free hydroxyls. For the less acidic framework hydroxyls in large cavities of H/sub 70/Na/sub 30/-Y zeolite the observed shift is 275 cm/sup -1/. With ZSM-5 zeolites, at least six types of electron-accepting sites are observed originating from nonframework Al species (band of CO in the interaction complex: 2132, 2222, 2202, 2195, and 2198 cm/sup -1/) and the Al/sub 2/O/sub 3/ microcrystalline phase (CO band at 2153 cm/sup -1/). The CO bond orders calculated by the CNDO/2 method for the CO interaction complexes with models of surface sites increase in the following order: > O-CO < > OH-CO approx. ..-->.. Al-CO approx. = Na-CO < alumina-CO approx. = Ca-CO < ..-->.. Si-CO < Al(cationic)-CO. A correlation between the calculated bond orders of CO and the observed vibrational frequencies of CO-forming interaction complexes is drawn.

  7. Treatment of swine wastewater using chemically modified zeolite and bioflocculant from activated sludge.

    PubMed

    Guo, Junyuan; Yang, Chunping; Zeng, Guangming

    2013-09-01

    Sterilization, alkaline-thermal and acid-thermal treatments were applied to activated sludge and the pre-treated sludge was used as raw material for Rhodococcus R3 to produce polymeric substances. After 60 h of fermentation, bioflocculant of 2.7 and 4.2 g L(-1) were produced in sterilized and alkaline-thermal treated sludge as compared to that of 0.9 g L(-1) in acid-thermal treated sludge. Response surface methodology (RSM) was employed to optimize the treatment process of swine wastewater using the composite of bioflocculant and zeolite modified by calcining with MgO. The optimal flocculating conditions were bioflocculant of 24 mg L(-1), modified zeolite of 12 g L(-1), CaCl2 of 16 mg L(-1), pH of 8.3 and contact time of 55 min, and the corresponding removal rates of COD, ammonium and turbidity were 87.9%, 86.9%, and 94.8%. The use of the composite by RSM provides a feasible way to improve the pollutant removal efficiencies and recycle high-level of ammonium from wastewater. PMID:23810950

  8. The active site of low-temperature methane hydroxylation in iron-containing zeolites.

    PubMed

    Snyder, Benjamin E R; Vanelderen, Pieter; Bols, Max L; Hallaert, Simon D; Böttger, Lars H; Ungur, Liviu; Pierloot, Kristine; Schoonheydt, Robert A; Sels, Bert F; Solomon, Edward I

    2016-08-18

    An efficient catalytic process for converting methane into methanol could have far-reaching economic implications. Iron-containing zeolites (microporous aluminosilicate minerals) are noteworthy in this regard, having an outstanding ability to hydroxylate methane rapidly at room temperature to form methanol. Reactivity occurs at an extra-lattice active site called α-Fe(ii), which is activated by nitrous oxide to form the reactive intermediate α-O; however, despite nearly three decades of research, the nature of the active site and the factors determining its exceptional reactivity are unclear. The main difficulty is that the reactive species-α-Fe(ii) and α-O-are challenging to probe spectroscopically: data from bulk techniques such as X-ray absorption spectroscopy and magnetic susceptibility are complicated by contributions from inactive 'spectator' iron. Here we show that a site-selective spectroscopic method regularly used in bioinorganic chemistry can overcome this problem. Magnetic circular dichroism reveals α-Fe(ii) to be a mononuclear, high-spin, square planar Fe(ii) site, while the reactive intermediate, α-O, is a mononuclear, high-spin Fe(iv)=O species, whose exceptional reactivity derives from a constrained coordination geometry enforced by the zeolite lattice. These findings illustrate the value of our approach to exploring active sites in heterogeneous systems. The results also suggest that using matrix constraints to activate metal sites for function-producing what is known in the context of metalloenzymes as an 'entatic' state-might be a useful way to tune the activity of heterogeneous catalysts. PMID:27535535

  9. Decolorization/Deodorization of Zein via Activated Carbons and Molecular Sieves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of commercial activated carbons generated from different media and selective microporous zeolites with different pore sizes were used in a batch system to sequester the low molecular weight odor and color contaminants in commercial zein products. Because the adsorbents can also adsorb prot...

  10. Highly selective uptake of carbon dioxide on the zeolite |Na10.2KCs0.8|-LTA- a possible sorbent for biogas upgrading.

    PubMed

    Cheung, Ocean; Wardecki, Dariusz; Bacsik, Zoltán; Vasiliev, Petr; McCusker, Lynne B; Hedin, Niklas

    2016-06-28

    The|Na10.2KCs0.8|8[Al12Si12O48]8(Fm3[combining macron]c)-LTA zeolite adsorbs CO2-over-CH4 with a high selectivity (over 1500). The uptake of carbon dioxide is also high (3.31 mmol g(-1), 293 K, 101 kPa). This form of zeolite A is a very promising adsorbent for applications such as biogas upgrading, where keeping the adsorption of methane to a minimum is crucial. PMID:27251457

  11. Is [FeO](2+) the active center also in iron containing zeolites? A density functional theory study of methane hydroxylation catalysis by Fe-ZSM-5 zeolite.

    PubMed

    Rosa, Angela; Ricciardi, Giampaolo; Jan Baerends, Evert

    2010-04-19

    Arguments are put forward that the active alpha-oxygen site in the Fe-ZSM-5 catalyst consists of the FeO(2+) moiety. It is demonstrated that this zeolite site for FeO(2+) indeed obeys the design principles for high reactivity of the FeO(2+) moiety proposed earlier: a ligand environment consisting of weak equatorial donors (rather oxygen based than nitrogen based) and very weak or absent trans axial donor. The alpha-oxygen site would then owe its high reactivity to the same electronic structure features that lends FeO(2+) its high activity in biological systems, as well as in the classical Fenton chemistry. PMID:20302356

  12. Synthesis, Structure, and Carbon Dioxide Capture Properties of Zeolitic Imidazolate Frameworks

    SciTech Connect

    Phan, Anh; Doonan, Christian J.; Uribe-Romo, Fernando J.; Knobler, Carolyn B.; O’Keeffe, Michael; Yaghi, Omar M.

    2010-01-19

    Zeolites are one of humanity’s most important synthetic products. These aluminosilicate-based materials represent a large segment of the global economy. Indeed, the value of zeolites used in petroleum refining as catalysts and in detergents as water softeners is estimated at $350 billion per year. A major current goal in zeolite chemistry is to create a structure in which metal ions and functionalizable organic units make up an integral part of the framework. Such a structure, by virtue of the flexibility with which metal ions and organic moieties can be varied, is viewed as a key to further improving zeolite properties and accessing new applications. Recently, it was recognized that the Si-O-Si preferred angle in zeolites (145°) is coincident with that of the bridging angle in the M-Im-M fragment (where M is Zn or Co and Im is imidazolate), and therefore it should be possible to make new zeolitic imidazolate frameworks (ZIFs) with topologies based on those of tetrahedral zeolites. This idea was successful and proved to be quite fruitful; within the last 5 years over 90 new ZIF structures have been reported. The recent application of high-throughput synthesis and characterization of ZIFs has expanded this structure space significantly: it is now possible to make ZIFs with topologies previously unknown in zeolites, in addition to mimicking known structures. In this Account, we describe the general preparation of crystalline ZIFs, discussing the methods that have been developed to create and analyze the variety of materials afforded. We include a comprehensive list of all known ZIFs, including structure, topology, and pore metrics. We also examine how complexity might be introduced into new structures, highlighting how link-link interactions might be exploited to effect particular cage sizes, create polarity variations between pores, or adjust framework robustness, for example. The chemical and thermal stability of ZIFs permit many applications, such as the

  13. Modelling active sites for the Beckmann rearrangement reaction in boron-containing zeolites and their interaction with probe molecules.

    PubMed

    Lezcano-González, Inés; Vidal-Moya, Alejandro; Boronat, Mercedes; Blasco, Teresa; Corma, Avelino

    2010-06-28

    Theoretical calculations and in situ solid state NMR spectroscopy have been combined to get insight on the nature of the active sites for the Beckmann rearrangement reaction in borosilicate zeolites. The interaction of a B site in zeolite Beta with a series of probe molecules (ammonia, pyridine, acetone and water) has been modelled and the (15)N and (11)B NMR isotropic chemical shift of the resulting complexes calculated and compared with experimental in situ NMR results. This approach has allowed validation of the methodology to model the adsorption on a zeolite boron site of molecules of varying basicity which are either protonated or non-protonated. The limitation is that theoretical calculations overestimate the effect of molecular adsorption through hydrogen bonds on the calculated isotropic (11)B NMR chemical shift.Theoretical and experimental results on the adsorption of acetophenone and cyclohexanone oximes on zeolite B-Beta indicate that Brønsted acid sites protonate the oximes, changing the boron coordination from trigonal to tetrahedral. Comparison of theoretical and experimental (15)N NMR chemical shifts of the adsorbed amides (acetanilide and epsilon-caprolactam) indicates that they are non-protonated, and the (11)B NMR spectra show that, as expected, boron remains in trigonal coordination with an isotropic delta(11)B(exp) which differs from the calculated value delta(11)B(calc). PMID:20454729

  14. Novel Synthesis Method of Micronized Ti-Zeolite Na-A and Cytotoxic Activity of Its Silver Exchanged Form

    PubMed Central

    Youssef, H. F.; Hegazy, W. H.; Abo-almaged, H. H.; El-Bassyouni, G. T.

    2015-01-01

    The core-shell method is used as a novel synthetic process of micronized Ti-Zeolite Na-A which involves calcination at 700°C of coated Egyptian Kaolin with titanium tetrachloride in acidic medium as the first step. The produced Ti-coated metakaolinite is subjected to microwave irradiation at low temperature of 80°C for 2 h. The prepared micronized Ti-containing Zeolites-A (Ti-Z-A) is characterized by FTIR, XRF, XRD, SEM, and EDS elemental analysis. Ag-exchanged form of Ti-Z-Ag is also prepared and characterized. The Wt% of silver exchanged onto the Ti-Zeolite structure was determined by atomic absorption spectra. The in vitro cytotoxic activity of Ti-Z-Ag against human hepatocellular carcinoma cell line (HePG2), colon cell line carcinoma (HCT116), lung carcinoma cell line (A549), and human Caucasian breast adenocarcinoma (MCF7) is reported. The results were promising and revealed that the exchanged Ag form of micronized Ti-Zeolite-A can be used as novel antitumor drug. PMID:25705142

  15. Novel synthesis method of micronized ti-zeolite na-a and cytotoxic activity of its silver exchanged form.

    PubMed

    Youssef, H F; Hegazy, W H; Abo-Almaged, H H; El-Bassyouni, G T

    2015-01-01

    The core-shell method is used as a novel synthetic process of micronized Ti-Zeolite Na-A which involves calcination at 700°C of coated Egyptian Kaolin with titanium tetrachloride in acidic medium as the first step. The produced Ti-coated metakaolinite is subjected to microwave irradiation at low temperature of 80°C for 2 h. The prepared micronized Ti-containing Zeolites-A (Ti-Z-A) is characterized by FTIR, XRF, XRD, SEM, and EDS elemental analysis. Ag-exchanged form of Ti-Z-Ag is also prepared and characterized. The Wt% of silver exchanged onto the Ti-Zeolite structure was determined by atomic absorption spectra. The in vitro cytotoxic activity of Ti-Z-Ag against human hepatocellular carcinoma cell line (HePG2), colon cell line carcinoma (HCT116), lung carcinoma cell line (A549), and human Caucasian breast adenocarcinoma (MCF7) is reported. The results were promising and revealed that the exchanged Ag form of micronized Ti-Zeolite-A can be used as novel antitumor drug. PMID:25705142

  16. Increased thermal conductivity monolithic zeolite structures

    DOEpatents

    Klett, James; Klett, Lynn; Kaufman, Jonathan

    2008-11-25

    A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

  17. Synthesis and electrochemical capacitive properties of nitrogen-doped porous carbon micropolyhedra by direct carbonization of zeolitic imidazolate framework-11

    SciTech Connect

    Hao, Fei; Li, Li; Zhang, Xiaohua Chen, Jinhua

    2015-06-15

    Highlights: • Nitrogen-doped porous carbon micropolyhedra (N-PCMPs) were prepared from ZIF-11. • The activated N-PCMPs with fused KOH (N-PCMPs-A) have high specific surface area. • N-PCMPs-A exhibits high specific capacitance. • N-PCMPs-A reveals good cycling performance even at a high current density. - Abstract: Nitrogen-doped porous carbon micropolyhedra (N-PCMPs) were successfully prepared by direct carbonization of ZIF-11 polyhedra and further activated with fused KOH to obtain N-PCMPs-A. The morphology and microstructure of samples were examined by scanning electron microscopy, X-ray diffraction, and micropore and chemisorption analyzer. Electrochemical properties were characterized by cyclic voltammetry and galvanostatic charge/discharge method in 1.0 M H{sub 2}SO{sub 4} aqueous solution on a standard three-electrode system. Results show that, compared with N-PCMPs, N-PCMPs-A has higher specific surface area (2188 m{sup 2} g{sup −1}) and exhibits improved electrochemical capacitive properties (307 F g{sup −1} at 1.0 A g{sup −1}). The mass specific capacitance of N-PCMPs-A is also higher than that of most MOF-derived carbons, some carbide-derived carbons and carbon aerogel-derived carbons. In addition, the capacitance of the N-PCMPs-A retains 90% after 4000 cycles even at a high current density of 10 A g{sup −1}. These imply that N-PCMPs-A is the promising materials for the construction of a high-performance supercapacitor.

  18. Activated-Carbon Sorbent With Integral Heat-Transfer Device

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.; Yavrouian, Andre

    1996-01-01

    Prototype adsorption device used, for example, in adsorption heat pump, to store natural gas to power automobile, or to separate components of fluid mixtures. Device includes activated carbon held together by binder and molded into finned heat-transfer device providing rapid heating or cooling to enable rapid adsorption or desorption of fluids. Concepts of design and fabrication of device equally valid for such other highly thermally conductive devices as copper-finned tubes, and for such other high-surface-area sorbents as zeolites or silicates.

  19. Zeolitic imidazole framework templated synthesis of nanoporous carbon as a novel fiber coating for solid-phase microextraction.

    PubMed

    Zhang, Shuaihua; Yang, Qian; Li, Zhi; Wang, Wenchang; Wang, Chun; Wang, Zhi

    2016-02-01

    A new solid-phase microextraction (SPME) fiber coating material, a zeolitic imidazole framework-67 (ZIF-67) templated nanoporous carbon, Co-NPC, was fabricated by one-step direct carbonization of ZIF-67 without using any other carbon precursors. The prepared Co-NPC was then coated onto a functionalized stainless steel wire by a simple physical coating method to prepare SPME fibers. By coupling the Co-NPC coated fiber based SPME with gas chromatography/micro-electron capture detection (GC/μECD), the developed method exhibited low limits of detection (0.07-0.45 ng g(-1)) and a wide linearity (0.30-50 ng g(-1)) for the determination of five organochlorine pesticides (OCPs) in vegetable samples. The method was applied to the analysis of cabbage, cucumber and celery cabbage samples, and the recoveries of the analytes were in the range of 87.9-103.9% with the relative standard deviations (RSDs) ranging from 5.1% to 10.4% (n = 5). Single fiber repeatability and fiber-to-fiber reproducibility values expressed as RSDs were in the range of 4.9-9.6% and 5.8-11.0%, respectively. The method was simple, convenient and feasible for the determination of OCPs in real samples. PMID:26699844

  20. Enhancing the antibacterial activity of the gold standard intracanal medicament with incorporation of silver zeolite: An in vitro study

    PubMed Central

    Ghatole, Kiran; Gowdra, Ramesh Halebathi Giriyappa; Azher, Samer; Sabharwal, Sumit; Singh, Veerandar T.; Sundararajan, Bharath Vardhana

    2016-01-01

    Background: Enterococcus faecalis is a persistent organism that plays a major role in the etiology of persistent periradicular lesions after root canal treatment has been associated with different forms of periradicular disease including primary endodontic infections and persistent infections. The present study compares the antibacterial activities of calcium hydroxide, calcium hydroxide mixed with silver zeolite, and calcium hydroxide mixed with 2% chlorhexidine against E. faecalis using direct contact test. Materials and Methods: The test materials of the in vitro experimental study were grouped as group 1—calcium hydroxide mixed with sterile water, group 2—2% silver zeolite added in calcium hydroxide mixed with sterile water, and group 3—calcium hydroxide mixed with 2% chlorhexidine. The bottom of microtiter plate were coated with freshly mixed tested material and a 10 μL of bacterial suspension was placed. After 1 h of incubation at 37°C, brain–heart infusion (BHI) broth (245 μL) was added and mixed for 2 min. These were designated as “subgroup 1” wells. A volume of 15 μL of broth then transferred from subgroup 1 wells to an adjacent set of four wells containing fresh BHI medium (215 μL); these wells were designated as “subgroup 2”’ wells. The optical density was measured by a spectrophotometer after the first day, third day, and seventh day. One-way analysis of variance (ANOVA) and Tukey tests were performed for the analysis. Results: Calcium hydroxide mixed with silver zeolite showed maximum antibacterial activity. Conclusion: Silver zeolite can be added in calcium hydroxide to enhance the latter's antibacterial activity against E. faecalis. PMID:27011937

  1. In-situ NMR studies of isobutane activation and exchange in zeolite beta.

    PubMed

    Truitt, Matthew J; White, Jeffery L

    2009-04-01

    (1)H solid-state NMR techniques have been used to simultaneously detect the reactivity of both catalyst and alkane reactant protons in an in-situ experimental design. Specifically, the activation of isobutane C-H bonds by the solid acid zeolite H-Beta is directly observed while the reaction is in progress, and the rate of proton transfer between the solid catalyst surface and gaseous isobutane is quantitatively measured using isotopic (1)H/(2)H exchange methods. Arrhenius analysis of isothermal kinetic runs revealed an apparent activation barrier of 70kJ/mole for the exchange process between isobutane and the 12-membered ring H-Beta, which exceeds our previously determined value of 57kJ/mole for isobutane in the 10-membered ring H-ZSM-5 (JACS 2006, v. 128, p. 1848). Estimation of true activation energies using heat of adsorption data from the literature combined with the experimentally measured apparent E(a) suggests that the true activation barrier differs by only 6-7kJ/mole in the two catalysts. We discuss the possibility that subtle shape selectivity, or inverse shape selectivity, and lattice solvation differences between the two catalysts account for the enhanced solvation of the isobutane transition state in HZSM-5 compared to the larger channel H-Beta. In all experiments, the isobutane reagent was treated to eliminate any unsaturated impurities that might serve as initiators for carbenium-ion mechanisms, and the active catalyst was free of any organic contaminants that might serve as a source of unsaturated initiators. PMID:19185469

  2. Antimicrobial Activity of Glass lonomer Cement Incorporated with Chlorhexidine-Loaded Zeolite Nanoparticles.

    PubMed

    Kim, Hyun-Jin; Son, Jun Sik; Kim, Kyo-Han; Kwon, Tae-Yub

    2016-02-01

    A functional dental restorative system with antimicrobial properties was developed using zeolite (ZE) nanoparticles (NPs) as a drug delivery carrier. ZE NPs loaded with chlorhexidine (CHX) were prepared using the ionic immobilization method. The resulting CHX-loaded ZE NPs were then incorporated into commercial dental glass ionomer cement (GIC). The average size of the CHX-loaded ZE NPs was about 100 to 200 nm, and the NPs were dispersed homogeneously in the GIC. The in vitro release profile of encapsulated GIC containing CHX showed an early release burst of approximately 30% of the total CHX by day 7, whereas GIC containing CHX-loaded ZE NPs showed a sustained release of CHX without the early release burst in a 4-week immersion study. The agar diffusion test results showed that the GIC incorporated with CHX-loaded ZE NPs showed a larger growth inhibition zone of Streptococcus mutans than GIC alone, indicating that this innovative delivery platform potently imparted antimicrobial activity to the GIC. Moreover, these findings suggest that a range of antimicrobial drugs that inhibit the growth of oral bacteria can be incorporated efficiently into dental GIC using CHX-loaded ZE NPs. PMID:27433603

  3. Dewatering Peat With Activated Carbon

    NASA Technical Reports Server (NTRS)

    Rohatgi, N. K.

    1984-01-01

    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.

  4. A new method for As(V) removal from waters by precipitation of mimetite Pb5(AsO4)3Cl on Pb-activated zeolite

    NASA Astrophysics Data System (ADS)

    Manecki, Maciej; Buszkiewicz, Urszula

    2016-04-01

    A new method for removal of arsenate AsO43‑ ions from aqueous solutions is proposed. The principle of the method stems from precipitation of very insoluble crystalline lead arsenate apatite (mimetite Pb5(AsO4)3Cl) induced by bringing in contact Pb-activated zeolite and As-contaminated water in the presence of Cl‑. Zeolite is activated by sorption of Pb2+ followed by washing with water to remove the excess of Pb and to desorbe weakly adsorbed ions. Lead adsorbed on zeolite is bound strong enough to prevent desorption by water but weak enough to undergo desorption induced by heterogeneous precipitation of mimetite nanocrystals on the surface of zeolite. The experiment consisted of two steps. In the first step, aliquots of 0.5 g of natural clinoptilolite zeolite (from Zeocem a.s., Bystré, Slovak Republic) were reacted with 40 mL of solutions containing 20, 100, 500, and 2000 mg Pb/L (pH =4.5; reaction for 30 minutes followed by centrifugation). The amount of Pb sorbed was calculated from the drop of Pb concentration in solution. Centrifuged zeolite was washed three times by mixing with 10 mL of DDI water, followed by centrifugation. No Pb was detected in the water after second washing. Wet pulp resulting from this stage was exposed to solutions containing 70 mg/L Cl‑ and various concentrations of AsO43‑ (2 and 100 mg As/L; pH=4). Complete removal of As was observed for 2 mg As/L solutions mixed with zeolite-20 and zeolite-100. The precipitation of mimetite Pb5(AsO4)3Cl in the form of hexagonal crystals ca. 0.25 μm in size was observed using SEM/EDS. This work is partially funded by AGH research grant no 11.11.140.319.

  5. Mixed-Metal Zeolitic Imidazolate Frameworks and their Selective Capture of Wet Carbon Dioxide over Methane.

    PubMed

    Nguyen, Nhung T T; Lo, Tien N H; Kim, Jaheon; Nguyen, Huong T D; Le, Toan B; Cordova, Kyle E; Furukawa, Hiroyasu

    2016-06-20

    A presynthesized, square planar copper imidazole complex, [Cu(imidazole)4](NO3)2, was utilized as a precursor in the synthesis of a new series of zeolitic imidazolate frameworks, termed ZIF-202, -203, and -204. The structures of all three members were solved by single-crystal X-ray diffraction analysis, which revealed ZIF-203 and -204 having successfully integrated square planar units within the backbones of their respective frameworks. As a result of this unit, the structures of both ZIF-203 and -204 were found to adopt unprecedented three-dimensional nets, namely, ntn and thl, respectively. One member of this series, ZIF-204, was demonstrated to be highly porous, exhibit exceptional stability in water, and selectively capture CO2 over CH4 under both dry and wet conditions without any loss in performance over three cycles. Remarkably, the regeneration of ZIF-204 was performed under the mild conditions of flowing a pure N2 gas through the material at ambient temperature. PMID:27248714

  6. Near infrared emission from molecule-like silver clusters confined in zeolite A assisted by thermal activation

    SciTech Connect

    Lin, Hui Imakita, Kenji; Rong Gui, Sa Chu; Fujii, Minoru

    2014-07-07

    Strong and broad near infrared (NIR) emission peaked at ~855 nm upon optimal excitation at 342 nm has been observed from molecule-like silver clusters (MLSCs) confined in zeolite A assisted by thermal activation. To the best of our knowledge, this is the first observation of NIR emission peaked at longer than 800 nm from MLSCs confined in solid matrices. The decay time of the NIR emission is over 10 μs, which indicates that it is a spin-forbidden transition. The ~855 nm NIR emission shows strong dependence on the silver loading concentration and the thermal activation temperature.

  7. Zeolite vitrification demonstration program: characterization of radioactive vitrified zeolite materials

    SciTech Connect

    Barner, J O; Daniel, J L; Marshall, R K

    1984-01-01

    The leach behavior of radioactive vitrified zeolite material was studied as part of the Three Mile Island (TMI) Zeolite Vitrification Program conducted by Pacific Northwest Laboratory (PNL). Experimental procedures, test results, and discussions of the results are presented. The leach behavior of material from three canisters of vitrified zeolite is discussed in terms of the normalized weight loss of the glass-formers and the normalized activity loss of the fission products cesium and strontium. The leach behavior of the radioactive vitrified zeolite material is also compared to the leach behavior of MCC 76-68 reference glass. The effects of changes in the surface microstructure of the vitrified zeolite that occurred during leaching are also presented. 3 references, 23 figures, 10 tables.

  8. Carbon-14 tracer study of the conversion of labeled n-propylcyclopentane during n-octane aromatization with a Pt-zeolite L catalyst

    SciTech Connect

    Chenshi Huang; Sparks, D.E.; Dabbagh, H.A.; Davis, B.H. )

    1992-03-01

    n-Propylene cyclopentane or n-propylcyclopentane labeled in the ring with {sup 14}C was converted together with n-octane using a Pt-KL zeolite catalyst operating at 482 C and ca. 14 bar. The products indicate that hydrogenolysis to produce isooctanes, not ring expansion to produce aromatics, is the major reaction pathway for the alkyl cyclopentane compound. Dilution of the {sup 14}C activity in n-propylcyclopentane during the conversion shows that C{sub 5} as well as C{sub 6} cyclization occurs during the conversion of n-octane. The current data were obtained with a catalyst that has a Pt crystal size range that is similar to those reported earlier. Furthermore, the conversion data for n-octane and n-propylcyclopentane using the Pt-KL zeolite catalyst are very similar to data obtained with catalysts based on other nonacidic supports where the Pt crystals cannot be located in a zeolite type channel. Thus, for n-octane conversion, it appears that the Pt in L zeolite catalysts has selectivities that are similar to Pt on other nonacidic supports.

  9. Activity of Ga, In and Cu modified MFI zeolites for amine reactions

    SciTech Connect

    Kanazirev, V.; Price, G.L.

    1994-08-01

    High densities of Ga, In and Cu cations (Me/Al=1) in MFI zeolites have been obtained via thermal treatment of mechanical mixtures of metal oxides with H-MFI resulting in solid state ion-exchange. Ga and In require an H{sub 2} reducing agent during thermal treatment while Cu requires only an absence of O{sub 2} and undergoes autoreduction during thermal treatment. Using both thermal analysis with MS detection and catalytic testing in a gradientless batch recirculating reactor, the modified catalysts have been shown to be highly reactive towards amines. The desorption features of 1-propanamine with cation containing MFI generally differ from those of pure HMFI zeolite. Propanenitrile, C{sub 2}-C{sub 6} alkenes and aromatics appear in the decomposition products. Catalytic experiments have revealed that Ga, In, and Cu zeolitic cations promote dehydrogenation and condensation reactions of propanamine to different extents. Such behavior probably results from Lewis acid interactions of the zeolite cation with the amine.

  10. Photocatalytic activity of undoped and Ag-doped TiO{sub 2}-supported zeolite for humic acid degradation and mineralization

    SciTech Connect

    Lazau, C.; Ratiu, C.; Orha, C.; Pode, R.; Manea, F.

    2011-11-15

    Highlights: {yields} Hybrid materials based on natural zeolite and TiO{sub 2} obtained by solid-state reaction. {yields} XRD proved the presence of anatase form of undoped and Ag-doped TiO{sub 2} onto zeolite. {yields} FT-IR spectra evidenced the presence on TiO{sub 2} bounded at the zeolite network. {yields} Ag-doped TiO{sub 2} onto zeolitic matrix exhibited an enhanced photocatalytic activity. -- Abstract: The hybrid materials based on natural zeolite and undoped and Ag-doped TiO{sub 2}, i.e., Z-Na-TiO{sub 2} and Z-Na-TiO{sub 2}-Ag, were successfully synthesized by solid-state reaction in microwave-assisted hydrothermal conditions. Undoped TiO{sub 2} and Ag-doped TiO{sub 2} nanocrystals were previously synthesized by sol-gel method. The surface characterization of undoped TiO{sub 2}/Ag-doped TiO{sub 2} and natural zeolite hybrid materials has been investigated by X-ray diffraction, DRUV-VIS spectroscopy, FT-IR spectroscopy, BET analysis, SEM microscopy and EDX analysis. The results indicated that anatase TiO{sub 2} is the dominant crystalline type as spherical form onto zeolitic matrix. The presence of Ag into Z-Na-TiO{sub 2}-Ag was confirmed by EDX analysis. The DRUV-VIS spectra showed that Z-Na-TiO{sub 2}-Ag exhibited absorption within the range of 400-500 nm in comparison with Z-Na-TiO{sub 2} catalyst. The enhanced photocatalytic activity of Z-Na-TiO{sub 2}-Ag catalyst is proved through the degradation and mineralization of humic acid under ultraviolet and visible irradiation.

  11. Fabrication of TiO2/MoS2@zeolite photocatalyst and its photocatalytic activity for degradation of methyl orange under visible light

    NASA Astrophysics Data System (ADS)

    Zhang, Weiping; Xiao, Xinyan; Zheng, Lili; Wan, Caixia

    2015-12-01

    TiO2/MoS2@zeolite composite photocatalysts with visible-light activity were fabricated via a simple ultrasonic-hydrothermal synthesis method, using TiCl4 as Ti source, MoS2 as a direct sensitizer, glycerol water solution with certain dispersion agent as hydrolytic agent, and zeolite as carrier. The structure, morphology, composition, optical properties, and specific surface area of the as-prepared photocatalysts were characterized by using XRD, FTIR, SEM-EDS, TEM, XPS, UV-vis, PL and BET analyzer, respectively. And the photocatalytic degradation of methyl orange (MO) in aqueous suspension has been employed to evaluate the photocatalytic activity and degradation kinetics of as-prepared photocatalysts with xenon lamp as irradiation source. The results indicate that: (1) TiO2/MoS2@zeolite composite photocatalysts exhibit enhanced photocatalytic activities for methyl orange (MO) degradation compared to Degussa P25; (2) photocatalytic degradation of MO obeys Langmuir-Hinshelwood kinetic model (pseudo-first order reaction), and its degradation rate constant (kapp) (2.304 h-1) is higher than that of Degussa P25 (0.768 h-1); (3) the heterostructure consisted of zeolite, MoS2 and TiO2 nanostructure could provide synergistic effect for degradation of MO due to the efficient electron transfer process and better absorption property of TiO2/MoS2@zeolite composite photocatalyst.

  12. Cooperativity between Al Sites Promotes Hydrogen Transfer and Carbon-Carbon Bond Formation upon Dimethyl Ether Activation on Alumina.

    PubMed

    Comas-Vives, Aleix; Valla, Maxence; Copéret, Christophe; Sautet, Philippe

    2015-09-23

    The methanol-to-olefin (MTO) process allows the conversion of methanol/dimethyl ether into olefins on acidic zeolites via the so-called hydrocarbon pool mechanism. However, the site and mechanism of formation of the first carbon-carbon bond are still a matter of debate. Here, we show that the Lewis acidic Al sites on the 110 facet of γ-Al2O3 can readily activate dimethyl ether to yield CH4, alkenes, and surface formate species according to spectroscopic studies combined with a computational approach. The carbon-carbon forming step as well as the formation of methane and surface formate involves a transient oxonium ion intermediate, generated by a hydrogen transfer between surface methoxy species and coordinated methanol on adjacent Al sites. These results indicate that extra framework Al centers in acidic zeolites, which are associated with alumina, can play a key role in the formation of the first carbon-carbon bond, the initiation step of the industrial MTO process. PMID:27162986

  13. Separating proteins with activated carbon.

    PubMed

    Stone, Matthew T; Kozlov, Mikhail

    2014-07-15

    Activated carbon is applied to separate proteins based on differences in their size and effective charge. Three guidelines are suggested for the efficient separation of proteins with activated carbon. (1) Activated carbon can be used to efficiently remove smaller proteinaceous impurities from larger proteins. (2) Smaller proteinaceous impurities are most efficiently removed at a solution pH close to the impurity's isoelectric point, where they have a minimal effective charge. (3) The most efficient recovery of a small protein from activated carbon occurs at a solution pH further away from the protein's isoelectric point, where it is strongly charged. Studies measuring the binding capacities of individual polymers and proteins were used to develop these three guidelines, and they were then applied to the separation of several different protein mixtures. The ability of activated carbon to separate proteins was demonstrated to be broadly applicable with three different types of activated carbon by both static treatment and by flowing through a packed column of activated carbon. PMID:24898563

  14. Characterization of activated states of ruthenium-containing zeolite NaHY

    SciTech Connect

    Sheu, Shie-Ping; Karge, H.G.; Schloegl, R.

    1997-06-01

    As has been proven earlier, ruthenium-containing NaHY zeolites are able to catalyze the decomposition of ammonia at temperatures from 300 to 450{degrees}C. In such catalysts, ruthenium cations are still present, even after heat treatment in high vacuum at 400{degrees}C; they can be detected using ammonia and/or pyridine as probes for Fourier transform IR spectroscopy. They reside both in supercages and in sodalite cages. Various intermediates of the decomposition of the Ru(NH{sub 3}){sub 6}NaY complex on heat treatment in high vacuum were identified via in situ IR spectroscopy; in particular, evidence for the formation of complexes with nitrosyl ligands was obtained. It was shown that partially decomposed (deammoniated) Ru(NH{sub 3}){sub 6}NaY complexes can be recovered to some extent by readsorption of ammonia. Ruthenium-containing species were localized either in the supercages or in the small cavities as shown by IR spectroscopy employing ammonia and pyridine as probes. The acidic properties of variously treated Ru(NH{sub 3}){sub 6}NaY zeolites were characterized via temperature-programmed desorption (TPD) of ammonia, which was monitored by mass spectrometry. A strong interaction between ruthenium-containing species and the zeolite framework, leading to a lack of overtone and combination modes in the near infrared, is confirmed. Investigations of Ru(NH{sub 3}){sub 6}NaY samples by X-ray photoelectron spectroscopy under the same conditions as applied for IR and TPD studies revealed that, at variance with the results usually obtained after heat treatment of Ru(NH{sub 3}){sub 6}NaY in high vacuum, no significant formation of ruthenium metal species through autoreduction occurred. Rather, a particular form of a cation-exchanged Ru, Na-Y zeolite was obtained. 24 refs., 18 figs., 2 tabs.

  15. Surface Engineered Zeolite: An Active Interface for Rapid Adsorption and Degradation of Toxic Contaminants in Water.

    PubMed

    Shaw, Ruchi; Sharma, Richa; Tiwari, Sangeeta; Tiwari, Sandeep Kumar

    2016-05-18

    Zeolite has been surface modified to form novel multifunctional materials having capability for simultaneous and facile removal of heavy metals [Pb(II)], organic pollutants [methylene blue dye], and microorganisms [E. Coli, S. Aureus, and Pseudomonas] from contaminated water. The unique concept involves formation of core-shell particles with a functional core of zeolite and a porous shell of ZnO nanoflakes which not only imparts photocatalytic and antibacterial properties but also renders the surface negatively charged, thereby facilitating rapid adsorption of Pb(II) and MB. The uniform formation of ZnO nanoflakes (shell) on the zeolite (core) surface has been confirmed by XRD, DRS, FE-SEM, and TEM studies. Metal ion adsorption studies under varying conditions of time and concentration indicate that the material follows the Langmuir isotherm model and pseudo-second-order kinetics with good correlation to the experimental data. The rapid and high adsorption capacity of the material for both Pb (II) and MB has been established while factors responsible for enhanced adsorption have been discussed. The antibacterial studies against Gram negative bacteria (E. Coli and Pseudomonas) and Gram positive bacteria (S. Aureus) showed good zone inhibition characteristics. The material can be regenerated and reused besides having ease of separation using simple techniques. Being multifunctional, efficient, nontoxic, energy neutral, and recyclable with no effluent generation, the material is an efficient and sustainable alternative for water purification. PMID:27093055

  16. Post-synthetic preparation of Sn-, Ti- and Zr-beta: a facile route to water tolerant, highly active Lewis acidic zeolites.

    PubMed

    Wolf, Patrick; Hammond, Ceri; Conrad, Sabrina; Hermans, Ive

    2014-03-21

    A two-step procedure for the post-synthetic preparation of Lewis acidic Sn-, Zr- and Ti-zeolite β is reported. Dealumination of a commercially available Al-β zeolite leads to the formation of highly siliceous material containing silanol nests, which can be filled in a second step via the solid-state ion-exchange or impregnation of an appropriate metal precursor. Spectroscopic studies indicate that each metal is subsequently coordinated within the zeolite framework, and that little or no bulk oxides are formed--despite the high metal loadings. The synthesised catalysts demonstrate excellent activity for the isomerisation of glyceraldehyde to dihydroxyacetone, a key model reaction for the upgrading of bio-renewable feedstocks, and the epoxidation of bulky olefins. PMID:24407516

  17. Performance of Spent Mushroom Farming Waste (SMFW) Activated Carbon for Ni (II) Removal

    NASA Astrophysics Data System (ADS)

    Desa, N. S. Md; Ghani, Z. Ab; Talib, S. Abdul; Tay, C. C.

    2016-07-01

    The feasibility of a low cost agricultural waste of spent mushroom farming waste (SMFW) activated carbon for Ni(II) removal was investigated. The batch adsorption experiments of adsorbent dosage, pH, contact time, metal concentration, and temperature were determined. The samples were shaken at 125 rpm, filtered and analyzed using ICP-OES. The fifty percent of Ni(II) removal was obtained at 0.63 g of adsorbent dosage, pH 5-6 (unadjusted), 60 min contact time, 50 mg/L Ni(II) concentration and 25 °C temperature. The evaluated SMFW activated carbon showed the highest performance on Ni(II) removal compared to commercial Amberlite IRC86 resin and zeolite NK3. The result indicated that SMFW activated carbon is a high potential cation exchange adsorbent and suitable for adsorption process for metal removal. The obtained results contribute toward application of developed SMFW activated carbon in industrial pilot study.

  18. Synthesis and testing of nanosized zeolite Y

    NASA Astrophysics Data System (ADS)

    Karami, Davood

    kept constant. The extent to which the nanosized zeolite Y was formed depended on the types and amount of the organic templates as well as the ageing duration. The activity testing of four FCC catalysts prepared by using CREY (Calcined Rare Earth ion-exchanged) zeolites with different particle sizes was carried out in a fluidized bench-scale batch riser simulator reactor. The starting zeolites NaY of different particle sizes were subjected to two cycles of ion exchange treatment. The particle size of the supported zeolites was varied between 150 and 1800 nm. The preparation of FCC catalysts was conducted by mixing the CREY zeolite with silica-alumina matrix and silica sol binder. Each catalyst contained 25% zeolite. The results of catalytic cracking demonstrated the significant effect of size reduction of the starting zeolite Y on catalytic performance of FCC catalyst. Keywords. Zeolite NaY, Faujasite, Nanosized particles, Nanozeolite, Nanotechnology, Synthesis, Crystallization, Seeding, Ageing, Precipitated silica, Sylopol silica, Fumed silica, Silica sol, Soluble silicates, Alumina, SAR or SiO2/Al2O3 Ratios, Sodium hydroxide, Sodium aluminate, Organic templates, TMAOH, Surfactant (CTAB), Ammonium Sulfate, BET surface area, BJH Pore Size Distribution, Zetasizer Particle Size Distribution, Powder XRD, 27Al Solid-State NMR, Catalytic Impregnation, CREY Zeolite, Silica-Alumina Matrix, Ion Exchange, FCC Catalyst, Catalytic cracking, Riser SimulatorRTM, Steaming, Zeolite HY, Utrastable Zeolite Y (USY)

  19. Brønsted activity of two-dimensional zeolites compared to bulk materials.

    PubMed

    Sauer, Joachim

    2016-07-01

    Different reactivity parameters yield different results for the relative acidity of zeolitic Brønsted sites in thin films and in bulk materials. Whereas the adsorption energies of ammonia and pyridine are about the same, the energy of deprotonation is much lower for two-dimensional systems than for three-dimensional systems. It is shown that this is due to the smaller effective dielectric constant of two-dimensional systems, which leads to much lower deprotonation energies, but also to much lower interaction energies between the protonated molecule and the negatively charged surface site. In the total adsorption energies, both effects nearly compensate each other. PMID:27063151

  20. Carbon dioxide (C{sup 16}O{sub 2} and C{sup 18}O{sub 2}) adsorption in zeolite Y materials: effect of cation, adsorbed water and particle size

    SciTech Connect

    Pragati Galhotra; Juan G. Navea; Sarah C. Larsen; Vicki H. Grassian

    2009-07-01

    In this study, CO{sub 2} adsorption in the presence and absence of co-adsorbed H{sub 2}O was investigated in zeolite Y. Several different zeolite Y materials were investigated including commercial NaY, commercial NaY ion-exchanged with Ba{sup 2+} and nanocrystalline NaY; herein referred to as NaY, BaY and nano-NaY. Following heating of these zeolites to 573 K and cooling to room temperature, CO{sub 2} was adsorbed as a function of pressure. FTIR spectra show that a majority of CO{sub 2} adsorbs in the pores of these three zeolites (NaY, BaY and nano-NaY) in a linear complex with the exchangeable cation, as indicated by the intense absorption band near 2350 cm{sup -1}, assigned to the 3 asymmetric stretch of adsorbed CO{sub 2}. Most interestingly is the formation of carbonate and bicarbonate on the external surface of nano-NaY zeolites as indicated by the presence of several broad absorption bands in the 1200-1800 cm{sup -1} region, suggesting unique sites for CO{sub 2} adsorption on the surface of the nanomaterial. For the other two zeolite materials investigated, bicarbonate formation is only evident in BaY zeolite in the presence of co-adsorbed water. Adsorption of {sup 18}O-labeled carbon dioxide and theoretical quantum chemical calculations confirm these assignments and conclusions. 28 refs., 9 figs., 3 tabs.

  1. Mechanistic investigations on dimethyl carbonate formation by oxidative carbonylation of methanol over a CuY zeolite: an operando SSITKA/DRIFTS/MS study.

    PubMed

    Engeldinger, Jana; Richter, Manfred; Bentrup, Ursula

    2012-02-21

    The simultaneous combination of steady state isotopic transient kinetic analysis (SSITKA) with diffuse reflectance Fourier transform spectroscopy (DRIFTS) and mass spectrometric (MS) analysis was applied to study the oxidative carbonylation of methanol (MeOH) to dimethyl carbonate (DMC) on a CuY zeolite catalyst prepared by incipient-wetness impregnation of commercial zeolite NH(4)-Y. The interaction of the catalyst with different reactants and reactant mixtures (O(2), CO, CO/O(2), MeOH/O(2), MeOH/CO, and MeOH/CO/O(2)) was studied in detail using (16)O(2)/(18)O(2) as well as (12)CO/(13)CO containing gas mixtures. DMC is produced via a monodentate monomethyl carbonate (MMC) species as intermediate which is formed by the concerted action of adsorbed methoxide and CO with gas phase MeOH. Adsorbed bidentate MMC species were found to be inactive. Lattice oxygen supplied by CuO(x) species is involved in the formation of MMC. Gas phase oxygen is needed to re-oxidize the catalyst but favours also the oxidation of CO to CO(2) and unselective oxidation reactions of MeOH to methyl formate, dimethoxymethane, and CO(2). The appropriate choice of reaction temperature and of the oxygen content in the reactant gas mixture was found to be indispensable for reaching high DMC selectivities. PMID:22090021

  2. Impact of zeolite aging in hot liquid water on activity for acid-catalyzed dehydration of alcohols

    SciTech Connect

    Vjunov, Aleksei; Derewinski, Miroslaw A.; Fulton, John L.; Camaioni, Donald M.; Lercher, Johannes A.

    2015-08-19

    The catalytic performance of zeolite in aqueous medium depends on a multitude of factors, such as the concentration and distribution of active sites and framework integrity. Al K–edge extended X–ray absorption fine structure and 27Al MAS NMR spectroscopies in combination with DFT calculations are used to determine the distribution of tetrahedral Al sites both qualitatively and quantitatively for both parent and 48 h 160 ºC water treated HBEA catalysts. There is no evidence of Al coordination modification after aging in water. The distribution and concentration of Al T–sites, active centers for the dehydration of cyclohexanol, do not markedly impact the catalytic performance in water, because the Brønsted acidic protons are present in the form of hydrated hydronium ions and thus have very similar acid properties. The results suggest that all Brønsted acid sites are equally active in aqueous medium. The decrease of zeolite catalytic performance after water treatment is attributed to the reduced concentration of Brønsted acid sites. Increasing the stability of pore walls and decreasing the rate of Si–O–Si group hydrolysis may result in improved apparent zeolite catalytic performance in aqueous medium. Authors thank B. W. Arey (PNNL) for HIM measurements, T. Huthwelker for support during Al XAFS measurements at the Swiss Light Source (PSI, Switzerland), J. Z. Hu and S. D. Burton (PNNL) for support during NMR experiments. This work was supported by the U. S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. MD acknowledges support by the Materials Synthesis and Simulation Across Scales (MS3 Initiative) conducted under Laboratory Directed Research & Development Program at PNNL. HIM imaging and NMR experiments were performed at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE Office of Science, Office of Biological

  3. Activated carbon to the rescue

    SciTech Connect

    Sen, S.

    1996-03-01

    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.

  4. Activated Carbon Composites for Air Separation

    SciTech Connect

    Contescu, Cristian I; Baker, Frederick S; Tsouris, Costas; McFarlane, Joanna

    2008-03-01

    In continuation of the development of composite materials for air separation based on molecular sieving properties and magnetic fields effects, several molecular sieve materials were tested in a flow system, and the effects of temperature, flow conditions, and magnetic fields were investigated. New carbon materials adsorbents, with and without pre-loaded super-paramagnetic nanoparticles of Fe3O4 were synthesized; all materials were packed in chromatographic type columns which were placed between the poles of a high intensity, water-cooled, magnet (1.5 Tesla). In order to verify the existence of magnetodesorption effect, separation tests were conducted by injecting controlled volumes of air in a flow of inert gas, while the magnetic field was switched on and off. Gas composition downstream the column was analyzed by gas chromatography and by mass spectrometry. Under the conditions employed, the tests confirmed that N2 - O2 separation occurred at various degrees, depending on material's intrinsic properties, temperature and flow rate. The effect of magnetic fields, reported previously for static conditions, was not confirmed in the flow system. The best separation was obtained for zeolite 13X at sub-ambient temperatures. Future directions for the project include evaluation of a combined system, comprising carbon and zeolite molecular sieves, and testing the effect of stronger magnetic fields produced by cryogenic magnets.

  5. Quantifying defects in zeolites and zeolite membranes

    NASA Astrophysics Data System (ADS)

    Hammond, Karl Daniel

    Zeolites are crystalline aluminosilicates that are frequently used as catalysts to transform chemical feedstocks into more useful materials in a size- or shape-selective fashion; they are one of the earliest forms of nanotechnology. Zeolites can also be used, especially in the form of zeolite membranes (layers of zeolite on a support), to separate mixtures based on the size of the molecules. Recent advances have also created the possibility of using zeolites as alkaline catalysts, in addition to their traditional applications as acid catalysts and catalytic supports. Transport and catalysis in zeolites are greatly affected by physical and chemical defects. Such defects can be undesirable (in the case of zeolite membranes), or desirable (in the case of nitrogen-doped alkaline zeolites). Studying zeolites at the relevant length scales requires indirect experimental methods such as vapor adsorption or atomic-scale modeling such as electronic structure calculations. This dissertation explores both experimental and theoretical characterization of zeolites and zeolite membranes. Physical defects, important in membrane permeation, are studied using physical adsorption experiments and models of membrane transport. The results indicate that zeolite membranes can be modeled as a zeolite powder on top of a support---a "supported powder," so to speak---for the purposes of adsorption. Mesoporosity that might be expected based on permeation and confocal microscopy measurements is not observed. Chemical defects---substitutions of nitrogen for oxygen---are studied using quantum mechanical models that predict spectroscopic properties. These models provide a method for simulating the 29Si NMR spectra of nitrogendefected zeolites. They also demonstrate that nitrogen substitutes into the zeolite framework (not just on the surface) under the proper reaction conditions. The results of these studies will be valuable to experimentalists and theorists alike in our efforts to understand the

  6. Intensification of ammonia removal from waste water in biologically active zeolitic ion exchange columns.

    PubMed

    Almutairi, Azel; Weatherley, Laurence R

    2015-09-01

    The use of nitrification filters for the removal of ammonium ion from waste-water is an established technology deployed extensively in municipal water treatment, in industrial water treatment and in applications such as fish farming. The process involves the development of immobilized bacterial films on a solid packing support, which is designed to provide a suitable host for the film, and allow supply of oxygen to promote aerobic action. Removal of ammonia and nitrite is increasingly necessary to meet drinking water and discharge standards being applied in the US, Europe and other places. Ion-exchange techniques are also effective for removal of ammonia (as the ammonium ion) from waste water and have the advantage of fast start-up times compared to biological filtration which in some cases may take several weeks to be fully operational. Here we explore the performance of ion exchange columns in which nitrifying bacteria are cultivated, with the goal of a "combined" process involving simultaneous ion-exchange and nitrification, intensified by in-situ aeration with a novel membrane module. There were three experimental goals. Firstly, ion exchange zeolites were characterized and prepared for comparative column breakthrough studies for ammonia removal. Secondly effective in-situ aeration for promotion of nitrifying bacterial growth was studied using a number of different membranes including polyethersulfone (PES), polypropylene (PP), nylon, and polytetra-fluoroethylene (PTFE). Thirdly the breakthrough performance of ion exchange columns filled with zeolite in the presence of aeration and in the presence of nitrifying bacteria was determined to establish the influence of biomass, and aeration upon breakthrough during ammonium ion uptake. The methodology adopted included screening of two types of the naturally occuring zeolite clinoptilolite for effective ammonia removal in continuous ion-exchange columns. Next, the performance of fixed beds of clinoptilolite in the

  7. Effect of the nature of a structure-forming additive on the physicochemical properties of zeolites and the activity of Zn-containing catalysts based on them in ethane aromatization

    NASA Astrophysics Data System (ADS)

    Vosmerikova, L. N.; Barbashin, Ya. E.; Vosmerikov, A. V.

    2014-03-01

    The effect the nature of the structure-forming additive has on the physicochemical properties of synthesized zeolites and the activity of Zn-containing catalysts prepared on their basis in converting ethane into aromatic hydrocarbons is studied. It is shown that the structure-forming additive plays an important role in the hydrothermal synthesis of zeolites. It is found that the highest activity and stability in ethane aromatization is exhibited by a catalyst based on a zeolite synthesized using hexamethylenediamine as a template.

  8. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na[sub 2]O added as NAOH instead of Na[sub 2]CO[sub 3] to avoid severe foaming due to CO[sub 2] evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  9. Reclaiming silver from silver zeolite

    SciTech Connect

    Reimann, G.A.

    1991-10-01

    Silver zeolite is used to capture radioiodines from air cleaning systems in some nuclear facilities at the Idaho National Engineering Laboratory. It may become radioactively contaminated and/or poisoned by hydrocarbon vapors, which diminishes its capacity for iodine. Silver zeolite contains up to 38 wt% silver. A pyrometallurgical process was developed to reclaim the silver before disposing of the unserviceable zeolite as a radioactive waste. A flux was formulated to convert the refractory aluminosilicate zeolite structure into a low-melting fluid slag, with Na{sub 2}O added as NAOH instead of Na{sub 2}CO{sub 3} to avoid severe foaming due to CO{sub 2} evolution. A propane-fired furnace was built to smelt 45 kg charges at 1300C in a carbon-bonded silicon carbide crucible. A total of 218 kg (7000 tr oz) of silver was reclaimed from 1050 kg of unserviceable zeolite. Silver recoveries of 97% were achieved, and the radioisotopes were fixed as stable silicates in a vitreous slag that was disposed of as a low level waste. Recovered silver was refined using oxygen and cast into 100 tr oz bars assaying 99.8+% silver and showing no radioactive contamination.

  10. Control of carbon monoxide (CO) from automobile exhaust by a dealuminated zeolite supported regenerative MnCo2O4 catalyst.

    PubMed

    Arun, P S; Ranjith, B P; Shibli, S M A

    2013-03-19

    We synthesized MnCo(2)O(4) catalyst with very high porosity on the surface of dealuminated zeolite molecular sieves (DAZMS) for CO oxidation under actual automobile conditions. The MnCo(2)O(4) catalyst was selected on the basis of preliminary DFT study using the software ADF BAND. The MnCo(2)O(4) catalyst had comparatively higher CO adsorption energy and very low oxygen vacancy formation energy. The synthesized MnCo(2)O(4)/DAZMS catalyst was characterized by XRD, XRF, BET, SEM, and Confocal Microscopy. The Confocal microscopic analysis revealed that porosity of the dealuminated zeolite surface was significantly enhanced after the catalyst loading process. The completely precious metal free and DAZMS-supported catalyst exhibited excellent CO oxidation ability with renewed activity for seven months under actual automobile conditions with reference to normal and cold start conditions. The synthesized MnCo(2)O(4)/DAZMS not only exhibited surprisingly high catalytic activity for CO oxidation at a temperature resembling a cold start period but was also sufficiently stable/active under actual automobile conditions and ambient conditions containing large amounts of CO,H(2)O,CO(2), and NO(x) at 155-715 °C. These significant results revealed the flexible use of the present catalyst system for a wide variety of automobiles from a small gasoline-fuelled vehicle to a large diesel-fuelled vehicle that may produce high CO-content exhaust. PMID:23406461

  11. Cracking process with catalyst of combined zeolites

    SciTech Connect

    Gladrow, E. M.; Winter, W. E.

    1981-09-01

    A hydrocarbon cracking catalyst comprises an ultrastable y-type crystalline zeolite, a small pore crystalline zeolite such as mordenite, an inorganic oxide matrix and, optionally, a porous inert component. The cracking catalyst has a high activity and selectivity for the production of high octane naphtha fractions from higher boiling point hydrocarbonaceous oils. Catalytic cracking processes utilizing the catalyst are also provided.

  12. [Life support of the Mars exploration crew. Control of a zeolite system for carbon dioxide removal from space cabin air within a closed air regeneration cycle].

    PubMed

    Chekov, Iu F

    2009-01-01

    The author describes a zeolite system for carbon dioxide removal integrated into a closed air regeneration cycle aboard spacecraft. The continuous operation of a double-adsorbent regeneration system with pCO2-dependable productivity is maintained through programmable setting of adsorption (desorption) semicycle time. The optimal system regulation curve is presented within the space of statistical performance family obtained in quasi-steady operating modes with controlled parameters of the recurrent adsorption-desorption cycle. The automatically changing system productivity ensures continuous intake of concentrated CO2. Control of the adsorption-desorption process is based on calculation of the differential adsorption (desorption) heat from gradient of adsorbent and test inert substance temperatures. The adaptive algorithm of digital control is implemented through the standard spacecraft interface with the board computer system and programmable microprocessor-based controllers. PMID:19621802

  13. Photoconductivity of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    Kuriyama, K.; Dresselhaus, M. S.

    1990-08-01

    The photoconductivity is measured on a high-surface-area disordered carbon material, namely activated carbon fibers, to investigate their electronic properties. Measurements of decay time, recombination kinetics and temperature dependence of the photoconductivity generally reflect the electronic properties of a material. The material studied in this paper is a highly disordered carbon derived from a phenolic precursor, having a huge specific surface area of 1000--2000m{sup 2}/g. Our preliminary thermopower measurements suggest that this carbon material is a p-type semiconductor with an amorphous-like microstructure. The intrinsic electrical conductivity, on the order of 20S/cm at room temperature, increases with increasing temperature in the range 30--290K. In contrast with the intrinsic conductivity, the photoconductivity in vacuum decreases with increasing temperature. The recombination kinetics changes from a monomolecular process at room temperature to a biomolecular process at low temperatures. The observed decay time of the photoconductivity is {approx equal}0.3sec. The magnitude of the photoconductive signal was reduced by a factor of ten when the sample was exposed to air. The intrinsic carrier density and the activation energy for conduction are estimated to be {approx equal}10{sup 21}/cm{sup 3} and {approx equal}20meV, respectively. The majority of the induced photocarriers and of the intrinsic carriers are trapped, resulting in the long decay time of the photoconductivity and the positive temperature dependence of the conductivity.

  14. Improved zeolitic isocracking catalysts

    SciTech Connect

    Dahlberg, A.J.; Habib, M.M.; Moore, R.O.; Law, D.V.; Convery, L.J.

    1995-09-01

    Chevron Research Company introduced the first low pressure, low temperature catalytic hydrocracking process--ISOCRACKING--in 1959. Within the last four years, Chevron has developed and commercialized three new zeolitic ISOCRACKING catalysts. ICR 209 is Chevron`s latest noble metal ISOCRACKING catalyst. It offers improved liquid yield stability, longer life, and superior polynuclear aromatics control compared to its predecessor. ICR 209`s high hydrogenation activity generates the highest yields of superior quality jet fuel of any zeolitic ISOCRACKING catalyst. The second new ISOCRACKING catalyst, ICR 208, is a base metal catalyst which combines high liquid selectivity and high light naphtha octane in hydrocrackers operating for maximum naphtha production. ICR 210 is another new base metal catalyst which offers higher liquid yields and longer life than ICR 208 by virtue of a higher hydrogenation-to-acidity ratio. Both ICR 208 and ICR 210 have been formulated to provide higher liquid yield throughout the cycle and longer cycle length than conventional base metal/zeolite catalysts. This paper will discuss the pilot plant and commercial performances of these new ISOCRACKING catalysts.

  15. A comprehensive study on photocatalytic activity of supported Ni/Pb sulfide and oxide systems onto natural zeolite nanoparticles.

    PubMed

    Babaahamdi-Milani, Majid; Nezamzadeh-Ejhieh, Alireza

    2016-11-15

    The Ni(II)-Pb(II) exchanged clinoptilolite nanoparticles (NCP) were transformed to corresponding oxides and sulfides via calcination and sulfiding processes, respectively. The obtained catalysts were characterized by XRD, FT-IR, TEM and DRS and used in photodegradation of p-nitrophenol (4-NP) aqueous solution under Hg-lamp irradiation. Results showed considerable increase in activity of the coupled semiconductors with respect to monocomponent one. In NiO-PbO-NCP system, conduction band (CB) of NiO is enough negative for easily migration of photogenerated electrons to CB-PbO level, while such phenomena take place from more negative CB-PbS level to CB-NiS level in NiS-PbS-NCP. These phenomena significantly prevented from electron-hole recombination which increased photocatalytic activity of the coupled semiconductors. Best photodegradation activities obtained by NiO1.3%-PbO14.7%-NCP and NiS2.1%-PbS10.0%-NCP, confirming semiconductors' mass-ratio dependence of the photocatalytic process. The supported coupled semiconductors showed blue shifts in band gap energies with respect to the bulk semiconductors which confirm formation of semiconductors nanoparticles inside the zeolite framework. The highest degradation percentage of 4-NP was obtained at: 0.5gL(-1) photocatalysts, 15mgL(-1) 4-NP at pH 7.5. PMID:27427895

  16. Spectroscopic investigations of humic-like acids formed via polycondensation reactions between glycine, catechol and glucose in the presence of natural zeolites

    NASA Astrophysics Data System (ADS)

    Fukuchi, Shigeki; Miura, Akitaka; Okabe, Ryo; Fukushima, Masami; Sasaki, Masahide; Sato, Tsutomu

    2010-10-01

    Polycondensation reactions between low-molecular-weight compounds, such as amino acids, sugars and phenols, are crucially important processes in the formation of humic substances, and clay minerals have the ability to catalyze these reactions. In the present study, catechol (CT), glycine (Gly) and glucose (Gl) were used as representative phenols, amino acids and sugars, respectively, and the effects of the catalytic activities of natural zeolites on polycondensation reactions between these compounds were investigated. The extent of polycondensation was evaluated by measuring the specific absorbance at 600 nm ( E600) as an index of the degree of darkening. After a 3-week incubation period, the E600 values for solutions that contained zeolite samples were 4-10 times greater than those measured in the absence of zeolite, suggesting that the zeolite had, in fact, catalyzed the polycondensation reaction. The humic-like acids (HLAs) produced in the reactions were isolated, and their elemental composition and molecular weights determined. When formed in the presence of a zeolite, the nitrogen contents and molecular weights for the HLAs were significantly higher, compared to the HLA sample formed in the absence of zeolite. In addition, solid-state CP-MAS 13C NMR spectra and carboxylic group analyses of the HLA samples indicated that the concentration of carbonyl carbon species for quinones and ketones produced in the presence of zeolite were higher than the corresponding values for samples produced in the absence of a zeolite. Carbonyl carbons in quinones and ketones indicate the nucleophilic characteristics of the samples. Therefore, a nitrogen atom in Gly, which serves as nucleophile, is incorporated into quinones and ketones in CT and Gl. The differences in the catalytic activities of the zeolite samples can be attributed to differences in their transition metal content (Fe, Mn and Ti), which function as Lewis acids.

  17. Activated, coal-based carbon foam

    DOEpatents

    Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

    2004-12-21

    An ablation resistant, monolithic, activated, carbon foam produced by the activation of a coal-based carbon foam through the action of carbon dioxide, ozone or some similar oxidative agent that pits and/or partially oxidizes the carbon foam skeleton, thereby significantly increasing its overall surface area and concurrently increasing its filtering ability. Such activated carbon foams are suitable for application in virtually all areas where particulate or gel form activated carbon materials have been used. Such an activated carbon foam can be fabricated, i.e. sawed, machined and otherwise shaped to fit virtually any required filtering location by simple insertion and without the need for handling the "dirty" and friable particulate activated carbon foam materials of the prior art.

  18. Activated, coal-based carbon foam

    SciTech Connect

    Rogers, Darren Kenneth; Plucinski, Janusz Wladyslaw

    2009-06-09

    An ablation resistant, monolithic, activated, carbon foam produced by the activation of a coal-based carbon foam through the action of carbon dioxide, ozone or some similar oxidative agent that pits and/or partially oxidizes the carbon foam skeleton, thereby significantly increasing its overall surface area and concurrently increasing its filtering ability. Such activated carbon foams are suitable for application in virtually all areas where particulate or gel form activated carbon materials have been used. Such an activated carbon foam can be fabricated, i.e. sawed, machined and otherwise shaped to fit virtually any required filtering location by simple insertion and without the need for handling the "dirty" and friable particulate activated carbon foam materials of the prior art.

  19. Design of activated carbon/activated carbon asymmetric capacitors

    NASA Astrophysics Data System (ADS)

    Piñeiro-Prado, Isabel; Salinas-Torres, David; Ruiz Rosas, Ramiro; Morallon, Emilia; Cazorla-Amoros, Diego

    2016-03-01

    Supercapacitors are energy storage devices that offer a high power density and a low energy density in comparison with batteries. Their limited energy density can be overcome by using asymmetric configuration in mass electrodes, where each electrode works within their maximum available potential window, rendering the maximum voltage output of the system. Such asymmetric capacitors must be optimized through careful electrochemical characterization of the electrodes for accurate determination of the capacitance and the potential stability limits. The results of the characterization are then used for optimizing mass ratio of the electrodes from the balance of stored charge. The reliability of the design largely depends on the approach taken for the electrochemical characterization. Therefore, the performance could be lower than expected and even the system could break down, if a well thought out procedure is not followed. In this work, a procedure for the development of asymmetric supercapacitors based on activated carbons is detailed. Three activated carbon materials with different textural properties and surface chemistry have been systematically characterized in neutral aqueous electrolyte. The asymmetric configuration of the masses of both electrodes in the supercapacitor has allowed to cover a higher potential window, resulting in an increase of the energy density of the three devices studied when compared with the symmetric systems, and an improved cycle life.

  20. Mercury binding on activated carbon

    SciTech Connect

    Bihter Padak; Michael Brunetti; Amanda Lewis; Jennifer Wilcox

    2006-11-15

    Density functional theory has been employed for the modeling of activated carbon (AC) using a fused-benzene ring cluster approach. Oxygen functional groups have been investigated for their promotion of effective elemental mercury binding on AC surface sites. Lactone and carbonyl functional groups yield the highest mercury binding energies. Further, the addition of halogen atoms has been considered to the modeled surface, and has been found to increase the AC's mercury adsorption capacity. The mercury binding energies increase with the addition of the following halogen atoms, F {gt} Cl {gt} Br {gt} I, with the fluorine addition being the most promising halogen for increasing mercury adsorption.

  1. ZEOLITES: EFFECTIVE WATER PURIFIERS

    EPA Science Inventory

    Zeolites are known for their adsorption, ion exchange and catalytic properties. Various natural zeolites are used as odor and moisture adsorbents and water softeners. Due to their acidic nature, synthetic zeolites are commonly employed as solid acid catalysts in petrochemical ind...

  2. Silver-Zeolite Combined to Polyphenol-Rich Extracts of Ascophyllum nodosum: Potential Active Role in Prevention of Periodontal Diseases

    PubMed Central

    Tamanai-Shacoori, Zohreh; Chandad, Fatiha; Rébillard, Amélie; Cillard, Josiane; Bonnaure-Mallet, Martine

    2014-01-01

    The purpose of this study was to evaluate various biological effects of silver-zeolite and a polyphenol-rich extract of A. nodosum (ASCOP) to prevent and/or treat biofilm-related oral diseases. Porphyromonas gingivalis and Streptococcus gordonii contribute to the biofilm formation associated with chronic periodontitis. In this study, we evaluated in vitro antibacterial and anti-biofilm effects of silver-zeolite (Ag-zeolite) combined to ASCOP on P. gingivalis and S. gordonii growth and biofilm formation capacity. We also studied the anti-inflammatory and antioxidant capacities of ASCOP in cell culture models. While Ag-zeolite combined with ASCOP was ineffective against the growth of S. gordonii, it showed a strong bactericidal effect on P. gingivalis growth. Ag-zeolite combined with ASCOP was able to completely inhibit S. gordonii monospecies biofilm formation as well as to reduce the formation of a bi-species S. gordonii/P. gingivalis biofilm. ASCOP alone was ineffective towards the growth and/or biofilm formation of S. gordonii and P. gingivalis while it significantly reduced the secretion of inflammatory cytokines (TNFα and IL-6) by LPS-stimulated human like-macrophages. It also exhibited antioxidant properties and decreased LPS induced lipid peroxidation in gingival epithelial cells. These findings support promising use of these products in future preventive or therapeutic strategies against periodontal diseases. PMID:25272151

  3. Correlation of the changes in the framework and active Cu sites for typical Cu/CHA zeolites (SSZ-13 and SAPO-34) during hydrothermal aging.

    PubMed

    Su, Wenkang; Li, Zhenguo; Peng, Yue; Li, Junhua

    2015-11-21

    The relative framework stability of Cu/CHA zeolites (SAPO-34 and SSZ-13) was studied during hydrothermal aging at 800 °C, and the fundamental mechanism for the framework change was investigated. Additionally, the relationship between the variation in the framework and active SCR reaction sites was established. SAPO-34 showed stronger stability during hydrothermal aging than SSZ-13. The results showed that dealumination occurred in the SSZ-13 zeolite, leading to the loss of crystallinity and a severe decrease of the Brönsted acid sites. Simultaneously, the detached Al(OH)3 species deactivated the Cu species by the transformation of isolated Cu(2+) ions to CuAlOx species. While the vacancy in the SAPO-34 framework caused by desilication could be healed with the migration of extra-framework Al and P atoms to the defects. And the Cu species showed a certain degree of aggregation with the improved redox ability of the aged Cu/SAPO-34 zeolite and the acidic properties were well maintained. PMID:26462874

  4. Methods of using structures including catalytic materials disposed within porous zeolite materials to synthesize hydrocarbons

    DOEpatents

    Rollins, Harry W.; Petkovic, Lucia M.; Ginosar, Daniel M.

    2011-02-01

    Catalytic structures include a catalytic material disposed within a zeolite material. The catalytic material may be capable of catalyzing a formation of methanol from carbon monoxide and/or carbon dioxide, and the zeolite material may be capable of catalyzing a formation of hydrocarbon molecules from methanol. The catalytic material may include copper and zinc oxide. The zeolite material may include a first plurality of pores substantially defined by a crystal structure of the zeolite material and a second plurality of pores dispersed throughout the zeolite material. Systems for synthesizing hydrocarbon molecules also include catalytic structures. Methods for synthesizing hydrocarbon molecules include contacting hydrogen and at least one of carbon monoxide and carbon dioxide with such catalytic structures. Catalytic structures are fabricated by forming a zeolite material at least partially around a template structure, removing the template structure, and introducing a catalytic material into the zeolite material.

  5. Zeolite catalysis: technology

    SciTech Connect

    Heinemann, H.

    1980-07-01

    Zeolites have been used as catalysts in industry since the early nineteen sixties. The great majority of commercial applications employ one of three zeolite types: zeolite Y; Mordenite; ZSM-5. By far the largest use of zeolites is in catalytic cracking, and to a lesser extent in hydrocracking. This paper reviews the rapid development of zeolite catalysis and its application in industries such as: the production of gasoline by catalytic cracking of petroleum; isomerization of C/sub 5/ and C/sub 6/ paraffin hydrocarbons; alkylation of aromatics with olefins; xylene isomerization; and conversion of methanol to gasoline.

  6. Low Absorption Vitreous Carbon Reactors for Operando XAS: A Case Study on Cu/Zeolites for Selective Catalytic Reduction of NOx by NH3

    SciTech Connect

    Kispersky, Vincent F.; Kropf, A. Jeremy; Ribeiro, Fabio H.; Miller, Jeffrey T.

    2012-01-01

    We describe the use of vitreous carbon as an improved reactor material for an operando X-ray absorption spectroscopy (XAS) plug-flow reactor. These tubes significantly broaden the operating range for operando experiments. Using selective catalytic reduction (SCR) of NOx by NH₃ on Cu/Zeolites (SSZ-13, SAPO-34 and ZSM-5) as an example reaction, we illustrate the high-quality XAS data achievable with these reactors. The operando experiments showed that in Standard SCR conditions of 300 ppm NO, 300 ppm NH₃, 5% O₂, 5% H₂O, 5% CO₂ and balance He at 200 °C, the Cu was a mixture of Cu(I) and Cu(II) oxidation states. XANES and EXAFS fitting found the percent of Cu(I) to be 15%, 45% and 65% for SSZ-13, SAPO-34 and ZSM-5, respectively. For Standard SCR, the catalytic rates per mole of Cu for Cu/SSZ-13 and Cu/SAPO-34 were about one third of the rate per mole of Cu on Cu/ZSM-5. Based on the apparent lack of correlation of rate with the presence of Cu(I), we propose that the reaction occurs via a redox cycle of Cu(I) and Cu(II). Cu(I) was not found in in situSCR experiments on Cu/Zeolites under the same conditions, demonstrating a possible pitfall of in situ measurements. A Cu/SiO₂ catalyst, reduced in H₂ at 300 °C, was also used to demonstrate the reactor's operando capabilities using a bending magnet beamline. Analysis of the EXAFS data showed the Cu/SiO₂ catalyst to be in a partially reduced Cu metal–Cu(I) state. In addition to improvements in data quality, the reactors are superior in temperature, stability, strength and ease of use compared to previously proposed borosilicate glass, polyimide tubing, beryllium and capillary reactors. The solid carbon tubes are non-porous, machinable, can be operated at high pressure (tested at 25 bar), are inert, have high material purity and high X-ray transmittance.

  7. Discovery of optimal zeolites for challenging separations and chemical conversions through predictive materials modeling

    NASA Astrophysics Data System (ADS)

    Siepmann, J. Ilja; Bai, Peng; Tsapatsis, Michael; Knight, Chris; Deem, Michael W.

    2015-03-01

    Zeolites play numerous important roles in modern petroleum refineries and have the potential to advance the production of fuels and chemical feedstocks from renewable resources. The performance of a zeolite as separation medium and catalyst depends on its framework structure and the type or location of active sites. To date, 213 framework types have been synthesized and >330000 thermodynamically accessible zeolite structures have been predicted. Hence, identification of optimal zeolites for a given application from the large pool of candidate structures is attractive for accelerating the pace of materials discovery. Here we identify, through a large-scale, multi-step computational screening process, promising zeolite structures for two energy-related applications: the purification of ethanol beyond the ethanol/water azeotropic concentration in a single separation step from fermentation broths and the hydroisomerization of alkanes with 18-30 carbon atoms encountered in petroleum refining. These results demonstrate that predictive modeling and data-driven science can now be applied to solve some of the most challenging separation problems involving highly non-ideal mixtures and highly articulated compounds. Financial support from the Department of Energy Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Award DE-FG02-12ER16362 is gratefully acknowledged.

  8. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyan, M.; Lafferty, C.; Kimber, G.

    1996-10-01

    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.

  9. Preparation of zeolite supported TiO2, ZnO and ZrO2 and the study on their catalytic activity in NOx reduction and 1-pentanol dehydration

    NASA Astrophysics Data System (ADS)

    Fatimah, Is

    2016-03-01

    Preparation of zeolite supported TiO2, ZnO and ZrO2 and their catalytic activity was studied. Activated natural zeolite from Indonesia was utilized for the preparation and catalytic activity test on NOx reduction by NH3 and also 1-pentanol dehydration were examined. Physicochemical characterization of materials was studied by x-ray diffraction (XRD) measurement, scanning electron microscope, solid acidity determination and also gas sorption analysis. The results confirmed that the preparation gives some improvements on physicochemical characters suitable for catalysis mechanism in those reactions. Solid acidity and specific surface area contributed significantly to the activity.

  10. Thermodynamic modeling of natural zeolite stability

    SciTech Connect

    Chipera, S.J.; Bish, D.L.

    1997-06-01

    Zeolites occur in a variety of geologic environments and are used in numerous agricultural, commercial, and environmental applications. It is desirable to understand their stability both to predict future stability and to evaluate the geochemical conditions resulting in their formation. The use of estimated thermodynamic data for measured zeolite compositions allows thermodynamic modeling of stability relationships among zeolites in different geologic environments (diagenetic, saline and alkaline lakes, acid rock hydrothermal, basic rock, deep sea sediments). This modeling shows that the relative cation abundances in both the aqueous and solid phases, the aqueous silica activity, and temperature are important factors in determining the stable zeolite species. Siliceous zeolites (e.g., clinoptilolite, mordenite, erionite) present in saline and alkaline lakes or diagenetic deposits formed at elevated silica activities. Aluminous zeolites (e.g., natrolite, mesolite/scolecite, thomsonite) formed in basic rocks in association with reduced silica activities. Likewise, phillipsite formation is favored by reduced aqueous silica activities. The presence of erionite, chabazite, and phillipsite are indicative of environments with elevated potassium concentrations. Elevated temperature, calcic water conditions, and reduced silica activity help to enhance the laumontite and wairakite stability fields. Analcime stability increases with increased temperature and aqueous Na concentration, and/or with decreased silica activity.

  11. SORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBONS

    EPA Science Inventory

    The mechanisms and rate of elemental mercury (HgO) capture by activated carbons have been studied using a bench-scale apparatus. Three types of activated carbons, two of which are thermally activated (PC-100 and FGD) and one with elemental sulfur (S) impregnated in it (HGR), were...

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

    NASA Astrophysics Data System (ADS)

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

    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 was found to be an interesting active material for supercapacitors, with a specific capacitance as high as 125 F/g.

  13. Carbon dioxide adsorption on micro-mesoporous composite materials of ZSM-12/MCM-48 type: The role of the contents of zeolite and functionalized amine

    SciTech Connect

    Santos, S.C.G.

    2015-10-15

    Highlights: • Synthesis of the micro-mesoporous composite materials of ZSM-12/MCM-48 type. • Application of these adsorbents in the carbon dioxide adsorption. • Effects of the contents of zeolite and amino group in the material surface on the CO{sub 2} capture efficiency. - Abstract: In this study ZSM-12/MCM-48 adsorbents have been synthesized at three ZSM-12 content, and also were functionalizated with amine groups by grafting. All the adsorbents synthesized were evaluated for CO{sub 2} capture. The X-ray diffraction analysis of the ZSM-12/MCM-48 composite showed the main characteristic peaks of ZSM-12 and MCM-48, and after the functionalization, the structure of MCM-48 on the composite impregnated was affected due amine presence. For the composites without amine, the ZSM-12 content was the factor determining in the adsorption capacity of CO{sub 2} and for the composites with amine the amount of amine was that influenced in the adsorption capacity.

  14. Hydrogen Selective Exfoliated Zeolite Membranes

    SciTech Connect

    Tsapatsis, Michael; Daoutidis, Prodromos; Elyassi, Bahman; Lima, Fernando; Iyer, Aparna; Agrawal, Kumar; Sabnis, Sanket

    2015-04-06

    The objective of this project was to develop and evaluate an innovative membrane technology at process conditions that would be representative of Integrated Gasification Combined Cycle (IGCC) advanced power generation with pre-combustion capture of carbon dioxide (CO2). This research focused on hydrogen (H2)-selective zeolite membranes that could be utilized to separate conditioned syngas into H2-rich and CO2-rich components. Both experiments and process design and optimization calculations were performed to evaluate the concept of ultra-thin membranes made from zeolites nanosheets. In this work, efforts in the laboratory were made to tackle two fundamental challenges in application of zeolite membranes in harsh industrial environments, namely, membrane thickness and membrane stability. Conventional zeolite membranes have thicknesses in the micron range, limiting their performance. In this research, we developed a method for fabrication of ultimately thin zeolite membranes based on zeolite nanosheets. A range of layered zeolites (MWW, RWR, NSI structure types) suitable for hydrogen separation was successfully exfoliated to their constituent nanosheets. Further, membranes were made from one of these zeolites, MWW, to demonstrate the potential of this group of materials. Moreover, long-term steam stability of these zeolites (up to 6 months) was investigated in high concentrations of steam (35 mol% and 95 mole%), high pressure (10 barg), and high temperatures (350 °C and 600 °C) relevant to conditions of water-gas-shift and steam methane reforming reactions. It was found that certain nanosheets are stable, and that stability depends on the concentration of structural defects. Additionally, models that represent a water-gas-shift (WGS) membrane reactor equipped with the zeolite membrane were developed for systems studies. These studies had the aim of analyzing the effect of the membrane reactor integration into IGCC plants

  15. Preparation of zeolite NaA for CO2 capture from nickel laterite residue

    NASA Astrophysics Data System (ADS)

    Du, Tao; Liu, Li-ying; Xiao, Penny; Che, Shuai; Wang, He-ming

    2014-08-01

    Zeolite NaA was successfully prepared from nickel laterite residue for the first time via a fusion-hydrothermal procedure. The structure and morphology of the as-synthesized zeolite NaA were characterized with a range of experimental techniques, such as X-ray diffraction, scanning electronic microscopy, and infrared spectroscopy. It was revealed that the structures of the produced zeolites were dependent on the molar ratios of the reactants and hydrothermal reaction conditions, so the synthesis conditions were optimized to obtain pure zeolite NaA. Adsorption of nitrogen and carbon dioxide on the prepared zeolite NaA was also measured and analyzed. The results showed that zeolite NaA could be prepared with reasonable purity, it had physicochemical properties comparable with zeolite NaA made from other methods, and it had excellent gas adsorption properties, thus demonstrating that zeolite NaA could be prepared from nickel laterite residue.

  16. Preparation of activated carbon by chemical activation under vacuum.

    PubMed

    Juan, Yang; Ke-Qiang, Qiu

    2009-05-01

    Activated carbons especially used for gaseous adsorption were prepared from Chinesefir sawdust by zinc chloride activation under vacuum condition. The micropore structure, adsorption properties, and surface morphology of activated carbons obtained under atmosphere and vacuum were investigated. The prepared activated carbons were characterized by SEM, FTIR, and nitrogen adsorption. It was found that the structure of the starting material is kept after activation. The activated carbon prepared under vacuum exhibited higher values of the BET surface area (up to 1079 m2 g(-1)) and total pore volume (up to 0.5665 cm3 g(-1)) than those of the activated carbon obtained under atmosphere. This was attributed to the effect of vacuum condition that reduces oxygen in the system and limits the secondary reaction of the organic vapor. The prepared activated carbon has well-developed microstructure and high microporosity. According to the data obtained, Chinese fir sawdust is a suitable precursor for activated carbon preparation. The obtained activated carbon could be used as a low-cost adsorbent with favorable surface properties. Compared with the traditional chemical activation, vacuum condition demands less energy consumption, simultaneity, and biomass-oil is collected in the procedure more conveniently. FTIR analysis showed that heat treatment would result in the aromatization of the carbon structure. PMID:19534162

  17. Conversion of Ethanol to Hydrocarbons on Hierarchical HZSM-5 Zeolites

    SciTech Connect

    Ramasamy, Karthikeyan K.; Zhang, He; Sun, Junming; Wang, Yong

    2014-02-22

    This study reports synthesis, characterization, and catalytic activity of the nano-size hierarchical HZSM-5 zeolite with high mesoporosity produced via a solvent evaporation procedure. Further, this study compares hierarchical zeolites with conventional HZSM-5 zeolite with similar Si/Al ratios for the ethanol-to-hydrocarbon conversion process. The catalytic performance of the hierarchical and conventional zeolites was evaluated using a fixed-bed reactor at 360 °C, 300 psig, and a weight hourly space velocity of 7.9 h-1. For the low Si/Al ratio zeolite (~40), the catalytic life-time for the hierarchical HZSM-5 was approximately 2 times greater than the conventional HZSM-5 despite its coking amount deposited 1.6 times higher than conventional HZSM-5. For the high Si/Al ratio zeolite (~140), the catalytic life-time for the hierarchical zeolite was approximately 5 times greater than the conventional zeolite and the amount of coking deposited was 2.1 times higher. Correlation was observed between catalyst life time, porosity, and the crystal size of the zeolite. The nano-size hierarchical HZSM-5 zeolites containing mesoporosity demonstrated improved catalyst life-time compared to the conventional catalyst due to faster removal of products, shorter diffusion path length, and the migration of the coke deposits to the external surface from the pore structure.

  18. Zeolite Nanoparticles for Selective Sorption of Plasma Proteins

    NASA Astrophysics Data System (ADS)

    Rahimi, M.; Ng, E.-P.; Bakhtiari, K.; Vinciguerra, M.; Ahmad, H. Ali; Awala, H.; Mintova, S.; Daghighi, M.; Bakhshandeh Rostami, F.; de Vries, M.; Motazacker, M. M.; Peppelenbosch, M. P.; Mahmoudi, M.; Rezaee, F.

    2015-11-01

    The affinity of zeolite nanoparticles (diameter of 8-12 nm) possessing high surface area and high pore volume towards human plasma proteins has been investigated. The protein composition (corona) of zeolite nanoparticles has been shown to be more dependent on the plasma protein concentrations and the type of zeolites than zeolite nanoparticles concentration. The number of proteins present in the corona of zeolite nanoparticles at 100% plasma (in vivo state) is less than with 10% plasma exposure. This could be due to a competition between the proteins to occupy the corona of the zeolite nanoparticles. Moreover, a high selective adsorption for apolipoprotein C-III (APOC-III) and fibrinogen on the zeolite nanoparticles at high plasma concentration (100%) was observed. While the zeolite nanoparticles exposed to low plasma concentration (10%) exhibited a high selective adsorption for immunoglobulin gamma (i.e. IGHG1, IGHG2 and IGHG4) proteins. The zeolite nanoparticles can potentially be used for selectively capture of APOC-III in order to reduce the activation of lipoprotein lipase inhibition during hypertriglyceridemia treatment. The zeolite nanoparticles can be adapted to hemophilic patients (hemophilia A (F-VIII deficient) and hemophilia B (F-IX deficient)) with a risk of bleeding, and thus might be potentially used in combination with the existing therapy.

  19. Zeolite Nanoparticles for Selective Sorption of Plasma Proteins

    PubMed Central

    Rahimi, M.; Ng, E.-P.; Bakhtiari, K.; Vinciguerra, M.; Ahmad, H. Ali; Awala, H.; Mintova, S.; Daghighi, M.; Bakhshandeh Rostami, F.; de Vries, M.; Motazacker, M. M.; Peppelenbosch, M. P.; Mahmoudi, M.; Rezaee, F.

    2015-01-01

    The affinity of zeolite nanoparticles (diameter of 8–12 nm) possessing high surface area and high pore volume towards human plasma proteins has been investigated. The protein composition (corona) of zeolite nanoparticles has been shown to be more dependent on the plasma protein concentrations and the type of zeolites than zeolite nanoparticles concentration. The number of proteins present in the corona of zeolite nanoparticles at 100% plasma (in vivo state) is less than with 10% plasma exposure. This could be due to a competition between the proteins to occupy the corona of the zeolite nanoparticles. Moreover, a high selective adsorption for apolipoprotein C-III (APOC-III) and fibrinogen on the zeolite nanoparticles at high plasma concentration (100%) was observed. While the zeolite nanoparticles exposed to low plasma concentration (10%) exhibited a high selective adsorption for immunoglobulin gamma (i.e. IGHG1, IGHG2 and IGHG4) proteins. The zeolite nanoparticles can potentially be used for selectively capture of APOC-III in order to reduce the activation of lipoprotein lipase inhibition during hypertriglyceridemia treatment. The zeolite nanoparticles can be adapted to hemophilic patients (hemophilia A (F-VIII deficient) and hemophilia B (F-IX deficient)) with a risk of bleeding, and thus might be potentially used in combination with the existing therapy. PMID:26616161

  20. Zeolite Nanoparticles for Selective Sorption of Plasma Proteins.

    PubMed

    Rahimi, M; Ng, E-P; Bakhtiari, K; Vinciguerra, M; Ali Ahmad, H; Awala, H; Mintova, S; Daghighi, M; Bakhshandeh Rostami, F; de Vries, M; Motazacker, M M; Peppelenbosch, M P; Mahmoudi, M; Rezaee, F

    2015-01-01

    The affinity of zeolite nanoparticles (diameter of 8-12 nm) possessing high surface area and high pore volume towards human plasma proteins has been investigated. The protein composition (corona) of zeolite nanoparticles has been shown to be more dependent on the plasma protein concentrations and the type of zeolites than zeolite nanoparticles concentration. The number of proteins present in the corona of zeolite nanoparticles at 100% plasma (in vivo state) is less than with 10% plasma exposure. This could be due to a competition between the proteins to occupy the corona of the zeolite nanoparticles. Moreover, a high selective adsorption for apolipoprotein C-III (APOC-III) and fibrinogen on the zeolite nanoparticles at high plasma concentration (100%) was observed. While the zeolite nanoparticles exposed to low plasma concentration (10%) exhibited a high selective adsorption for immunoglobulin gamma (i.e. IGHG1, IGHG2 and IGHG4) proteins. The zeolite nanoparticles can potentially be used for selectively capture of APOC-III in order to reduce the activation of lipoprotein lipase inhibition during hypertriglyceridemia treatment. The zeolite nanoparticles can be adapted to hemophilic patients (hemophilia A (F-VIII deficient) and hemophilia B (F-IX deficient)) with a risk of bleeding, and thus might be potentially used in combination with the existing therapy. PMID:26616161

  1. Beryllosilicate frameworks and zeolites.

    PubMed

    Armstrong, Jennifer A; Weller, Mark T

    2010-11-10

    Using inspiration derived from studying naturally occurring minerals, a series of framework beryllosilicates have been synthesized under hydrothermal conditions. These include two new zeolite topologies, a unique layered beryllosilicate, and beryllosilicate analogues of numerous aluminosilicate zeolites. Materials with the structure of the rare zeolite mineral nabesite have been synthesized for the first time, including both sodium and potassium derivatives. The structural chemistry of these beryllosilicates frameworks is discussed with reference to the networks of linked tetrahedra, which include the first instance of pentagonal, two-dimensional Cairo-tiling of silicate tetrahedra in one of the new zeolite topologies, their porosity, and their thermal stability. PMID:20949941

  2. Alkane Activation Initiated by Hydride Transfer: Co-conversion of Propane and Methanol over H-ZSM-5 Zeolite.

    PubMed

    Yu, Si-Min; Wu, Jian-Feng; Liu, Chong; Liu, Wei; Bai, Shi; Huang, Jun; Wang, Wei

    2015-06-15

    Co-conversion of alkane with another reactant over zeolite catalysts has emerged as a new approach to the long-standing challenge of alkane transformation. With the aid of solid-state NMR spectroscopy and GC-MS analysis, it was found that the co-conversion of propane and methanol can be readily initiated by hydride transfer at temperatures of ≥449 K over the acidic zeolite H-ZSM-5. The formation of (13)C-labeled methane and singly (13)C-labeled n-butanes in selective labeling experiments provided the first evidence for the initial hydride transfer from propane to surface methoxy intermediates. The results not only provide new insight into carbocation chemistry of solid acids, but also shed light on the low-temperature transformation of alkanes for industrial applications. PMID:25959356

  3. Correlations for Adsorption of Oxygenates onto Zeolites from Aqueous Solutions

    SciTech Connect

    Mallon, Elizabeth E.; Babineau, Ian J.; Kranz, Joshua I.; Guefrachi, Yasmine; Siepmann, J. Ilja; Bhan, Aditya; Tsapatsis, Michael

    2011-10-06

    Henry’s constants (K{sub ads}) for adsorption of C₃ polyfunctional molecules onto zeolites from aqueous solutions at 278 K were obtained and compared with the octanol–water partition coefficients, K{sub ow}, which were calculated using the prevalent ClogP group contribution method. K{sub ads} increases linearly with K{sub ow} for these adsorbates on H–ZSM-5 (MFI), FAU, BEA, and ITQ-1 (MWW). K{sub ads} values for C₂–C₆ diol adsorption at 278 K are also linearly correlated with K{sub ow} regardless of interactions in the bulk phase as measured by the solution activity coefficient. Exceptions to the correlation established between K{sub ads} and K{sub ow} are the adsorption of 1,2,ω-triols with carbon number greater than three on H–ZSM-5 and adsorption of all oxygenates studied on FER, which we postulate to be due to the effect of changing adsorption configuration with adsorbate/zeolite structure which cannot be captured by K{sub ow} alone. These results enable the prediction of separation selectivities of biomass-derived compounds on zeolite adsorbents.

  4. Adsorption of Methyl Tertiary Butyl Ether on Granular Zeolites: Batch and Column Studies

    PubMed Central

    Abu-Lail, Laila; Bergendahl, John A.; Thompson, Robert W.

    2010-01-01

    Methyl tertiary butyl ether (MTBE) has been shown to be readily removed from water with powdered zeolites, but the passage of water through fixed beds of very small powdered zeolites produces high friction losses not encountered in flow through larger sized granular materials. In this study, equilibrium and kinetic adsorption of MTBE onto granular zeolites, a coconut shell granular activated carbon (CS-1240), and a commercial carbon adsorbent (CCA) sample was evaluated. In addition, the effect of natural organic matter (NOM) on MTBE adsorption was evaluated. Batch adsorption experiments determined that ZSM-5 was the most effective granular zeolite for MTBE adsorption. Further equilibrium and kinetic experiments verified that granular ZSM-5 is superior to CS-1240 and CCA in removing MTBE from water. No competitive-adsorption effects between NOM and MTBE were observed for adsorption to granular ZSM-5 or CS-1240, however there was competition between NOM and MTBE for adsorption onto the CCA granules. Fixed-bed adsorption experiments for longer run times were performed using granular ZSM-5. The bed depth service time model (BDST) was used to analyze the breakthrough data. PMID:20153106

  5. Effect of silicate modulus and metakaolin incorporation on the carbonation of alkali silicate-activated slags

    SciTech Connect

    Bernal, Susan A.; Mejia de Gutierrez, Ruby; Provis, John L.; Rose, Volker

    2010-06-15

    Accelerated carbonation is induced in pastes and mortars produced from alkali silicate-activated granulated blast furnace slag (GBFS)-metakaolin (MK) blends, by exposure to CO{sub 2}-rich gas atmospheres. Uncarbonated specimens show compressive strengths of up to 63 MPa after 28 days of curing when GBFS is used as the sole binder, and this decreases by 40-50% upon complete carbonation. The final strength of carbonated samples is largely independent of the extent of metakaolin incorporation up to 20%. Increasing the metakaolin content of the binder leads to a reduction in mechanical strength, more rapid carbonation, and an increase in capillary sorptivity. A higher susceptibility to carbonation is identified when activation is carried out with a lower solution modulus (SiO{sub 2}/Na{sub 2}O ratio) in metakaolin-free samples, but this trend is reversed when metakaolin is added due to the formation of secondary aluminosilicate phases. High-energy synchrotron X-ray diffractometry of uncarbonated paste samples shows that the main reaction products in alkali-activated GBFS/MK blends are C-S-H gels, and aluminosilicates with a zeolitic (gismondine) structure. The main crystalline carbonation products are calcite in all samples and trona only in samples containing no metakaolin, with carbonation taking place in the C-S-H gels of all samples, and involving the free Na{sup +} present in the pore solution of the metakaolin-free samples. Samples containing metakaolin do not appear to have the same availability of Na{sup +} for carbonation, indicating that this is more effectively bound in the presence of a secondary aluminosilicate gel phase. It is clear that claims of exceptional carbonation resistance in alkali-activated binders are not universally true, but by developing a fuller mechanistic understanding of this process, it will certainly be possible to improve performance in this area.

  6. Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon

    SciTech Connect

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

    2009-06-01

    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 deg. C for an hour in each step. The catalytic growth of nanocarbon in C{sub 2}H{sub 4}/H{sub 2} was carried out at temperature of 550 deg. C for 2 hrs with different rotating angle in the fluidization system. SEM and N{sub 2} 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.

  7. Making Activated Carbon by Wet Pressurized Pyrolysis

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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

  8. Synthesis strategies in the search for hierarchical zeolites.

    PubMed

    Serrano, D P; Escola, J M; Pizarro, P

    2013-05-01

    Great interest has arisen in the past years in the development of hierarchical zeolites, having at least two levels of porosities. Hierarchical zeolites show an enhanced accessibility, leading to improved catalytic activity in reactions suffering from steric and/or diffusional limitations. Moreover, the secondary porosity offers an ideal space for the deposition of additional active phases and for functionalization with organic moieties. However, the secondary surface represents a discontinuity of the crystalline framework, with a low connectivity and a high concentration of silanols. Consequently, hierarchical zeolites exhibit a less "zeolitic behaviour" than conventional ones in terms of acidity, hydrophobic/hydrophilic character, confinement effects, shape-selectivity and hydrothermal stability. Nevertheless, this secondary surface is far from being amorphous, which provides hierarchical zeolites with a set of novel features. A wide variety of innovative strategies have been developed for generating a secondary porosity in zeolites. In the present review, the different synthetic routes leading to hierarchical zeolites have been classified into five categories: removal of framework atoms, surfactant-assisted procedures, hard-templating, zeolitization of preformed solids and organosilane-based methods. Significant advances have been achieved recently in several of these alternatives. These include desilication, due to its versatility, dual templating with polyquaternary ammonium surfactants and framework reorganization by treatment with surfactant-containing basic solutions. In the last two cases, the materials so prepared show both mesoscopic ordering and zeolitic lattice planes. Likewise, interesting results have been obtained with the incorporation of different types of organosilanes into the zeolite crystallization gels, taking advantage of their high affinity for silicate and aluminosilicate species. Crystallization of organofunctionalized species favours the

  9. The Transport Properties of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  10. The transport properties of activated carbon fibers

    SciTech Connect

    di Vittorio, S.L. . Dept. of Materials Science and Engineering); Dresselhaus, M.S. . Dept. of Electrical Engineering and Computer Science Massachusetts Inst. of Tech., Cambridge, MA . Dept. of Physics); Endo, M. . Dept. of Electrical Engineering); Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons. 19 refs., 4 figs.

  11. ACTIVATED CARBON FROM LIGNITE FOR WATER TREATMENT

    SciTech Connect

    Edwin S. Olson; Daniel J. Stepan

    2000-07-01

    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 North Dakota lignites with those of commercial carbons was conducted. Previous studies indicated that a commercial carbon prepared from Texas lignite (Darco HDB) was superior to those prepared from bituminous coals for water treatment. That the high alkali content of North Dakota lignites would result in favorable adsorptive properties for the very large humate molecules was hypothesized, owing to the formation of larger pores during activation. Since no standard humate test has been previously developed, initial adsorption testing was performed using smaller dye molecules with various types of ionic character. With the cationic dye, methylene blue, a carbon prepared from a high-sodium lignite (HSKRC) adsorbed more dye than the Darco HDB. The carbon from the low-sodium lignite was much inferior. With another cationic dye, malachite green, the Darco HDB was slightly better. With anionic dyes, methyl red and azocarmine-B, the results for the HSKRC and Darco HDB were comparable. A humate test was developed using Aldrich humic acid. The HSKRC and the Darco HDB gave equally high adsorption capacities for the humate (138 mg/g), consistent with the similarities observed in earlier tests. A carbon prepared from a high-sodium lignite from a different mine showed an outstanding improvement (201 mg/g). The carbons prepared from the low-sodium lignites from both mines showed poor adsorption capacities for humate. Adsorption isotherms were performed for the set of activated carbons in the humate system. These exhibited a complex behavior interpreted as resulting from two types

  12. Hollow Alveolus-Like Nanovesicle Assembly with Metal-Encapsulated Hollow Zeolite Nanocrystals.

    PubMed

    Dai, Chengyi; Zhang, Anfeng; Liu, Min; Gu, Lin; Guo, Xinwen; Song, Chunshan

    2016-08-23

    Inspired by the vesicular structure of alveolus which has a porous nanovesicle structure facilitating the transport of oxygen and carbon dioxide, we designed a hollow nanovesicle assembly with metal-encapsulated hollow zeolite that would enhance diffusion of reactants/products and inhibit sintering and leaching of active metals. This zeolitic nanovesicle has been successfully synthesized by a strategy which involves a one-pot hydrothermal synthesis of hollow assembly of metal-containing solid zeolite crystals without a structural template and a selective desilication-recrystallization accompanied by leaching-hydrolysis to convert the metal-containing solid crystals into metal-encapsulated hollow crystals. We demonstrate the strategy in synthesizing a hollow nanovesicle assembly of Fe2O3-encapsulated hollow crystals of ZSM-5 zeolite. This material possesses a microporous (0.4-0.6 nm) wall of hollow crystals and a mesoporous (5-17 nm) shell of nanovesicle with macropores (about 350 nm) in the core. This hierarchical structure enables excellent Fe2O3 dispersion (3-4 nm) and resistance to sintering even at 800 °C; facilitates the transport of reactant/products; and exhibits superior activity and resistance to leaching in phenol degradation. Hollow nanovesicle assembly of Fe-Pt bimetal-encapsulated hollow ZSM-5 crystals was also prepared. PMID:27429013

  13. Polymerized nanotube structures new zeolites?

    NASA Astrophysics Data System (ADS)

    Chernozatonskii, Leonid A.

    1998-11-01

    Polymers of single-wall carbon nanotubes - possible new zeolites - are modeled by molecular mechanics (MM2 calculation method). The polymerization at issue occurs by bonding of 6 sp 3 atomic pairs in each nanotube unit cell with similar atomic pairs located on 6 neighboring tubes like 2+2 cycloaddition in a rhombic two-dimensional C 60 polymer. It is shown these bonding in armchair ( n, n) SWNT ropes ( n=6, 8, 10, 12) changes positive radial curvature of tube segments to a negative one.

  14. Spectroscopic investigations of the photochemical properties of I. Spiropyran on y zeolite for photochromic applications II. Rhenium(I) bipyridyl tricarbonyl on mesoporous ZSM-5 zeolite and silica for photocatalytic reduction of carbon dioxide

    NASA Astrophysics Data System (ADS)

    Dubois, Kevin

    Immobilization of photoactive molecules on porous and nano-sized solid supports provides unique interactions which affect photophysical properties. In situ diffuse reflectance FTIR and UV-vis spectroscopies were primarily used to investigate the properties of surface functionalized materials. Spectroscopic characterization of photochromic spiropyran molecules physically adsorbed on Y zeolite revealed the importance of surface water in controlling kinetics and reversibility of photoswitching by stabilizing the merocyanine isomer. Re(bpy)(CO)3C1 was both physically adsorbed on a mesoporous ZSM-5 zeolite and covalently bound via the bipyridyl ligand on fumed silica to generate photocatalytic CO2 reduction materials. Upon light irradiation of the solids in the presence of CO2, in situ FTIR spectroscopy shows the formation of Re(bpy)(C0)3(COOH) and Re(bpy)(C0)3(CH0), respectively. FTIR photoexperiments using isotopic 13CO2 and EPR characterization of one electron reduced Re(bpy)(CO)3C1•- after photoirradiation support findings that successful CO2 photoreduction was achieved at the gas-surface interface.

  15. Adsorption of herbicides using activated carbons

    SciTech Connect

    Derbyshire, F.; Jagtoyen, M.; Lafferty, C.; Kimber, G.

    1996-12-31

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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.

  17. Hydrocarbon cracking with mixture of zeolites y and zsm-5

    SciTech Connect

    Gladrow, E.M.; Winter, W.E.

    1981-09-15

    A hydrocarbon cracking catalyst comprises an ultrastable y-type crystalline zeolite, a small pore crystalline zsm-type zeolite, an inorganic oxide matrix and, optionally, a porous inert component. The cracking catalyst has a high activity and selectivity for the production of high octane naphtha fractions from higher boiling point hydrocarbonaceous oils. Catalytic cracking processes utilizing the catalyst are also provided.

  18. Aluminum coordination and active sites on aluminas, Y zeolites and pillared silicates. Progress report, January 31, 1992--January 31, 1993

    SciTech Connect

    Fripiat, J.J.

    1992-12-31

    Effort was continued to characterize the nature of the Al species responsible for Lewis acidity in zeolites and in aluminas by NMR. While numerous techniques have been successful for scaling the acid strength of Broensted sites, the situation is not satisfactory for the Lewis acid sites. Initial rate of dehydrochlorination of 1,1,1-trichloroethane is sensitive to strength of Lewis acid sites. N-Butene isomerization has been extended to the new aluminas obtained from nano-sized precursors. O-Xylene isomerization was carried out in a recirculation reactor on H-mordenite samples containing Lewis or Broensted acid sites; effects of H{sub 2} and NO were also investigated. Cracking of methylcyclohexane and 3-methylpentane was investigated by EPR on H-mordenite. Sepiolite, a Mg silicate with zeolitic channels, had Al substituted for Si; the negative charge is balanced by, say, VO{sup 2+}. Transformation of ethanol into butadiene on this dual-function catalyst appears to result from a Prins reaction between acetaldeyde formed on the redox sites and ethylene resulting from dehydration of ethanol on Lewis sites.

  19. Organic solvent regeneration of granular activated carbon

    NASA Astrophysics Data System (ADS)

    Cross, W. H.; Suidan, M. T.; Roller, M. A.; Kim, B. R.; Gould, J. P.

    1982-09-01

    The use of activated carbon for the treatment of industrial waste-streams was shown to be an effective treatment. The high costs associated with the replacement or thermal regeneration of the carbon have prohibited the economic feasibility of this process. The in situ solvent regeneration of activated carbon by means of organic solvent extraction was suggested as an economically alternative to thermal regeneration. The important aspects of the solvent regeneration process include: the physical and chemical characteristics of the adsorbent, the pore size distribution and energy of adsorption associated with the activated carbon; the degree of solubility of the adsorbate in the organic solvent; the miscibility of the organic solvent in water; and the temperature at which the generation is performed.

  20. Microwave-assisted regeneration of activated carbon.

    PubMed

    Foo, K Y; Hameed, B H

    2012-09-01

    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

  1. Antimicrobial Activity of Carbon-Based Nanoparticles

    PubMed Central

    Maleki Dizaj, Solmaz; Mennati, Afsaneh; Jafari, Samira; Khezri, Khadejeh; Adibkia, Khosro

    2015-01-01

    Due to the vast and inappropriate use of the antibiotics, microorganisms have begun to develop resistance to the commonly used antimicrobial agents. So therefore, development of the new and effective antimicrobial agents seems to be necessary. According to some recent reports, carbon-based nanomaterials such as fullerenes, carbon nanotubes (CNTs) (especially single-walled carbon nanotubes (SWCNTs)) and graphene oxide (GO) nanoparticles show potent antimicrobial properties. In present review, we have briefly summarized the antimicrobial activity of carbon-based nanoparticles together with their mechanism of action. Reviewed literature show that the size of carbon nanoparticles plays an important role in the inactivation of the microorganisms. As major mechanism, direct contact of microorganisms with carbon nanostructures seriously affects their cellular membrane integrity, metabolic processes and morphology. The antimicrobial activity of carbon-based nanostructures may interestingly be investigated in the near future owing to their high surface/volume ratio, large inner volume and other unique chemical and physical properties. In addition, application of functionalized carbon nanomaterials as carriers for the ordinary antibiotics possibly will decrease the associated resistance, enhance their bioavailability and provide their targeted delivery. PMID:25789215

  2. Activated coconut shell charcoal carbon using chemical-physical activation

    NASA Astrophysics Data System (ADS)

    Budi, Esmar; Umiatin, Nasbey, Hadi; Bintoro, Ridho Akbar; Wulandari, Futri; Erlina

    2016-02-01

    The use of activated carbon from natural material such as coconut shell charcoal as metal absorbance of the wastewater is a new trend. The activation of coconut shell charcoal carbon by using chemical-physical activation has been investigated. Coconut shell was pyrolized in kiln at temperature about 75 - 150 °C for about 6 hours in producing charcoal. The charcoal as the sample was shieved into milimeter sized granule particle and chemically activated by immersing in various concentration of HCl, H3PO4, KOH and NaOH solutions. The samples then was physically activated using horizontal furnace at 400°C for 1 hours in argon gas environment with flow rate of 200 kg/m3. The surface morphology and carbon content of activated carbon were characterized by using SEM/EDS. The result shows that the pores of activated carbon are openned wider as the chemical activator concentration is increased due to an excessive chemical attack. However, the pores tend to be closed as further increasing in chemical activator concentration due to carbon collapsing.

  3. Zeolites: Exploring Molecular Channels

    SciTech Connect

    Arslan, Ilke; Derewinski, Mirek

    2015-05-22

    Synthetic zeolites contain microscopic channels, sort of like a sponge. They have many uses, such as helping laundry detergent lather, absorbing liquid in kitty litter, and as catalysts to produce fuel. Of the hundreds of types of zeolites, only about 15 are used for catalysis. PNNL catalysis scientists Ilke Arslan and Mirek Derewinksi are studying these zeolites to understand what make them special. By exploring the mystery of these microscopic channels, their fundamental findings will help design better catalysts for applications such as biofuel production.

  4. Diagram of Zeolite Crystals

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Center for Advanced Microgravity Materials Processing (CAMMP) in Cambridge, MA, a NASA-sponsored Commercial Space Center, is working to improve zeolite materials for storing hydrogen fuel. CAMMP is also applying zeolites to detergents, optical cables, gas and vapor detection for environmental monitoring and control, and chemical production techniques that significantly reduce by-products that are hazardous to the environment. Depicted here is one of the many here complex geometric shapes which make them highly absorbent. Zeolite experiments have also been conducted aboard the International Space Station

  5. Cooperativity between Al Sites Promotes Hydrogen Transfer and Carbon–Carbon Bond Formation upon Dimethyl Ether Activation on Alumina

    PubMed Central

    2015-01-01

    The methanol-to-olefin (MTO) process allows the conversion of methanol/dimethyl ether into olefins on acidic zeolites via the so-called hydrocarbon pool mechanism. However, the site and mechanism of formation of the first carbon–carbon bond are still a matter of debate. Here, we show that the Lewis acidic Al sites on the 110 facet of γ-Al2O3 can readily activate dimethyl ether to yield CH4, alkenes, and surface formate species according to spectroscopic studies combined with a computational approach. The carbon–carbon forming step as well as the formation of methane and surface formate involves a transient oxonium ion intermediate, generated by a hydrogen transfer between surface methoxy species and coordinated methanol on adjacent Al sites. These results indicate that extra framework Al centers in acidic zeolites, which are associated with alumina, can play a key role in the formation of the first carbon–carbon bond, the initiation step of the industrial MTO process. PMID:27162986

  6. ZEOLITE CHARACTERIZATION TESTING

    SciTech Connect

    Jacobs, W; Herbert Nigg, H

    2007-09-13

    The Savannah River Site isolates tritium from its process streams for eventual recycling. This is done by catalyzing the formation of tritiated water (from process streams) and then sorbing that water on a 3A zeolite (molsieve) bed. The tritium is recovered by regenerating the saturated bed into a Mg-based water cracking unit. The process described has been in use for about 15 years. Recently chloride stress corrosion cracking (SCC) was noted in the system piping. This has resulted in the need to replace the corroded piping and associated molecular sieve beds. The source of chlorine has been debated and one possible source is the zeolite itself. Since new materials are being purchased for recently fabricated beds, a more comprehensive analysis protocol for characterizing zeolite has been developed. Tests on archived samples indicate the potential for mobile chloride species to be generated in the zeolite beds.

  7. Composite zeolite membranes

    DOEpatents

    Nenoff, Tina M.; Thoma, Steven G.; Ashley, Carol S.; Reed, Scott T.

    2002-01-01

    A new class of composite zeolite membranes and synthesis techniques therefor has been invented. These membranes are essentially defect-free, and exhibit large levels of transmembrane flux and of chemical and isotopic selectivity.

  8. Microcystin-LR Adsorption by Activated Carbon.

    PubMed

    Pendleton, Phillip; Schumann, Russell; Wong, Shiaw Hui

    2001-08-01

    We use a selection of wood-based and coconut-based activated carbons to investigate the factors controlling the removal of the hepatotoxin microcystin-LR (m-LR) from aqueous solutions. The wood carbons contain both micropores and mesopores. The coconut carbons contain micropores only. Confirming previously published observations, we also find that the wood-based carbons adsorb more microcystin than the coconut-based carbons. From a combination of a judicious modification of a wood-based carbon's surface chemistry and of the solution chemistry, we demonstrate that both surface and solution chemistry play minor roles in the adsorption process, with the adsorbent surface chemistry exhibiting less influence than the solution chemistry. Conformational changes at low solution pH probably contribute to the observed increase in adsorption by both classes of adsorbent. At the solution pH of 2.5, the coconut-based carbons exhibit a 400% increased affinity for m-LR compared with 100% increases for the wood-based carbons. In an analysis of the thermodynamics of adsorption, using multiple temperature adsorption chromatography methods, we indicate that m-LR adsorption is an entropy-driven process for each of the carbons, except the most hydrophilic and mesoporous carbon, B1. In this case, exothermic enthalpy contributions to adsorption also exist. From our overall observations, since m-LR contains molecular dimensions in the secondary micropore width range, we demonstrate that it is important to consider both the secondary micropore and the mesopore volumes for the adsorption of m-LR from aqueous solutions. Copyright 2001 Academic Press. PMID:11446779

  9. A novel activated carbon for supercapacitors

    SciTech Connect

    Shen, Haijie; Liu, Enhui; Xiang, Xiaoxia; Huang, Zhengzheng; Tian, Yingying; Wu, Yuhu; Wu, Zhilian; Xie, Hui

    2012-03-15

    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.

  10. Synthesis and catalytic applications of combined zeolitic/mesoporous materials

    PubMed Central

    Vernimmen, Jarian; Cool, Pegie

    2011-01-01

    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

  11. Activated carbon monoliths for methane storage

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    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.

  12. DFT investigations of the reaction mechanism of diethyl carbonate synthesis catalyzed by Cu(I)/β or Pd(II)/β zeolites

    NASA Astrophysics Data System (ADS)

    Shen, Yongli; Wang, Shengping; Huang, Shouying; Li, Zhong; Ma, Xinbin

    2014-07-01

    Density functional theory (DFT) calculations are used to investigate the oxidative carbonylation of ethanol occurring on Cu(I)/β or Pd(II)/β. The thermochemistry and activation energy for all elementary steps involved in the formation of diethyl carbonate are presented. Upon calculation, we identify that the mechanisms for the formation of surface O atom are varying on different catalysts. Ethanol can react with the surface O atom to produce (C2H5O)(OH)-M/β (M = Cu+, Pd2+) species. And this intermediate can further react with carbon monoxide or ethanol to give monoethyl carbonate or di-ethoxied species ((C2H5O)2-M/β). Diethyl carbonate can form via two distinct reaction pathways: (I) ethanol reacts with monoethyl carbonate or (II) carbon monoxide inserts into di-ethoxide species. Upon calculation, we confirmed that both reaction pathways for the formation of DEC are accessible on Cu(I)/β catalyst, whereas only Path II is achievable on Pd(II)/β catalyst.

  13. Mechanochemical approach for selective deactivation of external surface acidity of ZSM-5 zeolite catalyst.

    PubMed

    Inagaki, Satoshi; Sato, Koki; Hayashi, Shunsuke; Tatami, Junichi; Kubota, Yoshihiro; Wakihara, Toru

    2015-03-01

    The acid sites associated with the external surface of zeolite particles are responsible for undesirable consecutive reactions, such as isomerization, alkylation, and oligomerization, resulting in a lower selectivity to a target product; therefore, the selective modification (deactivation) of the external surface of zeolite particles has been an important issue in zeolite science. Here, a new method for surface deactivation of zeolite catalyst was tested via a mechanochemical approach using powder composer. Postsynthetic mechanochemical treatment of ZSM-5 zeolite causes a selective deactivation of catalytically active sites existing only on the external surface, as a potentially useful catalyst for highly selective production of p-xylene. PMID:25654542

  14. Preparation of functionalized zeolitic frameworks

    DOEpatents

    Yaghi, Omar M.; Hayashi, Hideki; Banerjee, Rahul; Park, Kyo Sung; Wang, Bo; Cote, Adrien P.

    2014-08-19

    The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

  15. Preparation of functionalized zeolitic frameworks

    DOEpatents

    Yaghi, Omar M; Hayashi, Hideki; Banerjee, Rahul; Park, Kyo Sung; Wang, Bo; Cote, Adrien P

    2012-11-20

    The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

  16. Preparation of functionalized zeolitic frameworks

    DOEpatents

    Yaghi, Omar M; Furukawa, Hiroyasu; Wang, Bo

    2013-07-09

    The disclosure provides zeolitic frameworks for gas separation, gas storage, catalysis and sensors. More particularly the disclosure provides zeolitic frameworks (ZIFs). The ZIF of the disclosure comprises any number of transition metals or a homogenous transition metal composition.

  17. Copper cation removal in an electrokinetic cell containing zeolite.

    PubMed

    Elsayed-Ali, Omar H; Abdel-Fattah, Tarek; Elsayed-Ali, Hani E

    2011-01-30

    Zeolites are used in environmental remediation of soil or water to immobilize or remove toxic materials by cation exchange. An experiment was conducted to test the use a low electric field to direct the toxic cations towards the zeolite. An electrokinetic cell was constructed using carbon electrodes. Synthetic Linde Type A (LTA) zeolite was placed in the cell. Copper(II) chloride dissolved in water was used as a contaminant. The Cu(2+) concentration was measured for ten hours with and without an applied electric field. The removal of the Cu(2+) ions was accelerated by the applied field in the first two hours. For longer time, the electric field did not improve the removal rate of the Cu(2+) ions. The presence of zeolite and applied electric field complicates the chemistry near the cathode and causes precipitation of Cu(2+) ions as copper oxide on the surface of the zeolite. With increased electric field the zeolite farther away from the cathode had little cation exchange due to the higher drift velocity of the Cu(2+) ions. The results also show that, in the LTA Zeolite A pellets, the cation exchange of Cu is limited to a shell of several tens of micrometers. PMID:21109348

  18. Rapid synthesis of beta zeolites

    SciTech Connect

    Fan, Wei; Chang, Chun -Chih; Dornath, Paul; Wang, Zhuopeng

    2015-08-18

    The invention provides methods for rapidly synthesizing heteroatom containing zeolites including Sn-Beta, Si-Beta, Ti-Beta, Zr-Beta and Fe-Beta. The methods for synthesizing heteroatom zeolites include using well-crystalline zeolite crystals as seeds and using a fluoride-free, caustic medium in a seeded dry-gel conversion method. The Beta zeolite catalysts made by the methods of the invention catalyze both isomerization and dehydration reactions.

  19. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: the influence of zeolite chemical surface characteristics.

    PubMed

    Alejandro, Serguei; Valdés, Héctor; Manéro, Marie-Hélène; Zaror, Claudio A

    2014-06-15

    In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity. PMID:24794812

  20. Comparing gas separation performance between all known zeolites and their zeolitic imidazolate framework counterparts.

    PubMed

    Gómez-Álvarez, Paula; Hamad, Said; Haranczyk, Maciej; Ruiz-Salvador, A Rabdel; Calero, Sofia

    2016-01-01

    To find optimal porous materials for adsorption-based separations is a challenging task due to the extremely large number of possible pore topologies and compositions. New porous material classes such as Metal Organic Frameworks (MOFs) are emerging, and hope to replace traditionally used materials such as zeolites. Computational screening offers relatively fast searching for candidate structures as well as side-by-side comparisons between material families. This work is pioneering at examining the families comprised by the experimentally known zeolites and their respective Zeolitic Imidazolate Framework (ZIF) counterparts in the context of a number of environmental and industrial separations involving carbon dioxide, nitrogen, methane, oxygen, and argon. Additionally, unlike related published work, here all the targeted structures have been previously relaxed through energy minimization. On the first level of characterization, we considered a detailed pore characterization, identifying 24 zeolites as promising candidates for gas separation based on adsorbate sizes. The second level involved interatomic potential-based calculations to assess the adsorption performance of the materials. We found no correlation in the values of heat of adsorption between zeolites and ZIFs sharing the same topology. A number of structures were identified as potential experimental targets for CO2/N2, and CO2/CH4 affinity-based separations. PMID:26600432

  1. Preparation of activated carbons with mesopores by use of organometallics

    SciTech Connect

    Yamada, Yoshio; Yoshizawa, Noriko; Furuta, Takeshi

    1996-12-31

    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.

  2. 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...

  3. EPA'S RESEARCH PROGRAM IN GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Research into Granular Activated Carbon (GAC) for use in drinking water treatment has a long history in the Drinking Water Research Division and its predecessor organizations. tudies were conducted by the U.S. Public Health Service in the late fifties and early sixties to examine...

  4. 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...

  5. 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...

  6. Making Activated Carbon for Storing Gas

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

  7. The biomass derived activated carbon for supercapacitor

    NASA Astrophysics Data System (ADS)

    Senthilkumar, S. T.; Selvan, R. Kalai; Melo, J. S.

    2013-06-01

    In this work, the activated carbon was prepared from biowaste of Eichhornia crassipes by chemical activation method using KOH as the activating agent at various carbonization temperatures (600 °C, 700 °C and 800 °C). The disordered nature, morphology and surface functional groups of ACs were examined by XRD, SEM and FT-IR. The electrochemical properties of AC electrodes were studied in 1M H2SO4 in the potential range of -0.2 to 0.8 V using cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) techniques in a three electrode system. Subsequently, the fabricated supercapacitor using AC electrode delivered the higher specific capacitance and energy density of 509 F/g at current density of 1 mA/cm2 and 17 Wh/kg at power density of 0.416 W/g.

  8. Supercapacitor Electrodes from Activated Carbon Monoliths and Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Dolah, B. N. M.; Othman, M. A. R.; Deraman, M.; Basri, N. H.; Farma, R.; Talib, I. A.; Ishak, M. M.

    2013-04-01

    Binderless monoliths of supercapacitor electrodes were prepared by the carbonization (N2) and activation (CO2) of green monoliths (GMs). GMs were made from mixtures of self-adhesive carbon grains (SACG) of fibers from oil palm empty fruit bunches and a combination of 5 & 6% KOH and 0, 5 & 6% carbon nanotubes (CNTs) by weight. The electrodes from GMs containing CNTs were found to have lower specific BET surface area (SBET). The electrochemical behavior of the supercapacitor fabricated using the prepared electrodes were investigated by electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD). In general an addition of CNTs into the GMs reduces the equivalent series resistance (ESR) value of the cells. A cell fabricated using electrodes from GM with 5% CNT and 5% KOH was found to have the largest reduction of ESR value than that from the others GMs containing CNT. The cell has steeper Warburg's slope than that from its respective non-CNT GM, which reflect the smaller resistance for electrolyte ions to move into pores of electrodes despite these electrodes having largest reduction in specific BET surface area. The cell also has the smallest reduction of specific capacitance (Csp) and maintains the specific power range despite a reduction in the specific energy range due to the CNT addition.

  9. Hydrogen Adsorption in Zeolite Studied with Sievert and Thermogravimetric Methods

    NASA Astrophysics Data System (ADS)

    Lesnicenoks, P.; Sivars, A.; Grinberga, L.; Kleperis, J.

    2012-08-01

    Natural clinoptilolite (mixture from clinoptilolite, quartz and muscovite) is activated with palladium and tested for hydrogen adsorption capability at temperatures RT - 200°C. Thermogravimetric and volumetric methods showed that zeolite activated with palladium (1.25%wt) shows markedly high hydrogen adsorption capacity - up to 3 wt%. Lower amount of adsorbed hydrogen (~1.5 wt%) was found for raw zeolite and activated with higher amount of palladium sample. Hypothesis is proposed that the heating of zeolite in argon atmosphere forms and activates the pore structure in zeolite material, where hydrogen encapsulation (trapping) is believed to occur when cooling down to room temperature. An effect of catalyst (Pd) on hydrogen sorption capability is explained by spillover phenomena were less-porous fractions of natural clinoptilolite sample (quartz and muscovite) are involved.

  10. Application of artificial neural networks in prediction of diclofenac sodium release from drug-modified zeolites physical mixtures and antiedematous activity assessment.

    PubMed

    Krajišnik, Danina; Stepanović-Petrović, Radica; Tomić, Maja; Micov, Ana; Ibrić, Svetlana; Milić, Jela

    2014-04-01

    In this study, utilization of artificial neural network (ANN) models [static-multilayer perceptron (MLP) and generalized regression neural networks and dynamic-gamma one-layer network and recurrent one-layer network] for prediction of diclofenac sodium (DS) release from drug-cationic surfactant-modified zeolites physical mixtures comprising different surfactant/drug molar ratio (0.2-2.5) was performed. The inputs for ANNs trainings were surfactant/drug molar ratios, that is, drug loadings in the drug-modified zeolite mixtures, whereas the outputs were percents of drug release in predetermined time points during drug release test (8 h). The obtained results revealed that MLP showed the highest correlation between experimental and predicted drug release. The safety of both natural and cationic surfactant-modified zeolite as a potential excipient was confirmed in an acute toxicity testing during 72 h. DS (1.5, 5, 10, mg/kg, p.o.) as well as DS-modified zeolites mixtures produced a significant dose-dependent reduction of the rat paw edema induced by proinflammatory agent carrageenan. DS antiedematous effect was intensified and prolonged significantly by modified zeolite. These results could suggest the potential improvement in the treatment of inflammation by DS-modified zeolite mixtures. PMID:24496922

  11. Carbon nanomaterials: Biologically active fullerene derivatives.

    PubMed

    Bogdanović, Gordana; Djordjević, Aleksandar

    2016-01-01

    Since their discovery, fullerenes, carbon nanotubes, and graphene attract significant attention of researches in various scientific fields including biomedicine. Nano-scale size and a possibility for diverse surface modifications allow carbon nanoallotropes to become an indispensable nanostructured material in nanotechnologies, including nanomedicine. Manipulation of surface chemistry has created diverse populations of water-soluble derivatives of fullerenes, which exhibit different behaviors. Both non-derivatized and derivatized fullerenes show various biological activities. Cellular processes that underline their toxicity are oxidative, genotoxic, and cytotoxic responses.The antioxidant/cytoprotective properties of fullerenes and derivatives have been considered in the prevention of organ oxidative damage and treatment. The same unique physiochemical properties of nanomaterials may also be associated with potential health hazards. Non-biodegradability and toxicity of carbon nanoparticles still remain a great concern in the area of biomedical application. In this review, we report on basic physical and chemical properties of carbon nano-clusters--fullerenes, nanotubes, and grapheme--their specificities, activities, and potential application in biological systems. Special emphasis is given to our most important results obtained in vitro and in vivo using polyhydroxylated fullerene derivative C₆₀(OH)₂₄. PMID:27483572

  12. Enhanced capacitive properties of commercial activated carbon by re-activation in molten carbonates

    NASA Astrophysics Data System (ADS)

    Lu, Beihu; Xiao, Zuoan; Zhu, Hua; Xiao, Wei; Wu, Wenlong; Wang, Dihua

    2015-12-01

    Simple, affordable and green methods to improve capacitive properties of commercial activated carbon (AC) are intriguing since ACs possess a predominant role in the commercial supercapacitor market. Herein, we report a green reactivation of commercial ACs by soaking ACs in molten Na2CO3-K2CO3 (equal in mass ratios) at 850 °C combining the merits of both physical and chemical activation strategies. The mechanism of molten carbonate treatment and structure-capacitive activity correlations of the ACs are rationalized. Characterizations show that the molten carbonate treatment increases the electrical conductivity of AC without compromising its porosity and wettability of electrolytes. Electrochemical tests show the treated AC exhibited higher specific capacitance, enhanced high-rate capability and excellent cycle performance, promising its practical application in supercapacitors. The present study confirms that the molten carbonate reactivation is a green and effective method to enhance capacitive properties of ACs.

  13. Kinetics of adsorption with granular, powdered, and fibrous activated carbon

    SciTech Connect

    Shmidt, J.L.; Pimenov, A.V.; Lieberman, A.I.; Cheh, H.Y.

    1997-08-01

    The properties of three different types of activated carbon, fibrous, powdered, and granular, were investigated theoretically and experimentally. The adsorption rate of the activated carbon fiber was found to be two orders of magnitude higher than that of the granular activated carbon, and one order of magnitude higher than that of the powdered activated carbon. Diffusion coefficients of methylene blue in the fibrous, powdered, and granular activated carbons were determined experimentally. A new method for estimating the meso- and macropore surface areas in these carbons was proposed.

  14. Adsorption of chlorophenols on granular activated carbon

    SciTech Connect

    Yang, M.

    1993-12-31

    Studies were undertaken of the adsorption of chlorinated phenols from aqueous solution on granular activated carbon (Filtrasorb-400, 30 x 40 mesh). Single-component equilibrium adsorption data on the eight compounds in two concentration ranges at pH 7.0 fit the Langmuir equation better than the Freundlich equation. The adsorptive capacities at pH 7.0 increase from pentachlorophenol to trichlorophenols and are fairly constant from trichlorophenols to monochlorophenols. The adsorption process was found to be exothermic for pentachlorophenol and 2,4,6-trichlorophenol, and endothermic for 2,4-dichlorophenol and 4-chlorophenol. Equilibrium measurements were also conducted for 2,4,5-trichlorophenol, 2,4-dichlorophenol, and 4-chlorophenol over a wide pH range. A surface complexation model was proposed to describe the effect of pH on adsorption equilibria of chlorophenols on activated carbon. The simulations of the model are in excellent agreement with the experimental data. Batch kinetics studies were conducted of the adsorption of chlorinated phenols on granular activated carbon. The results show that the surface reaction model best describes both the short-term and long-term kinetics, while the external film diffusion model describes the short-term kinetics data very well and the linear-driving-force approximation improved its performance for the long-term kinetics. Multicomponent adsorption equilibria of chlorophenols on granular activated carbon was investigated in the micromolar equilibrium concentration range. The Langmuir competitive and Ideal Adsorbed Solution (IAS) models were tested for their performance on the three binary systems of pentachlorophenol/2,4,6-trichlorophenol, 2,4,6-trichlorophenol/2,4-dichlorophenol, and 2,4-dichlorophenol/4-chlorophenol, and the tertiary system of 2,4,6-trichlorophenol/2,4-dichlorophenol/4-chlorophenol, and found to fail to predict the two-component adsorption equilibria of the former two binary systems and the tertiary system.

  15. Aqueous mercury adsorption by activated carbons.

    PubMed

    Hadi, Pejman; To, Ming-Ho; Hui, Chi-Wai; Lin, Carol Sze Ki; McKay, Gordon

    2015-04-15

    Due to serious public health threats resulting from mercury pollution and its rapid distribution in our food chain through the contamination of water bodies, stringent regulations have been enacted on mercury-laden wastewater discharge. Activated carbons have been widely used in the removal of mercuric ions from aqueous effluents. The surface and textural characteristics of activated carbons are the two decisive factors in their efficiency in mercury removal from wastewater. Herein, the structural properties and binding affinity of mercuric ions from effluents have been presented. Also, specific attention has been directed to the effect of sulfur-containing functional moieties on enhancing the mercury adsorption. It has been demonstrated that surface area, pore size, pore size distribution and surface functional groups should collectively be taken into consideration in designing the optimal mercury removal process. Moreover, the mercury adsorption mechanism has been addressed using equilibrium adsorption isotherm, thermodynamic and kinetic studies. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using carbon activation processes with lower energy input, while achieving similar or even higher efficiencies. PMID:25644627

  16. APPRAISAL OF POWDERED ACTIVATED CARBON PROCESSES FOR MUNICIPAL WASTEWATER TREATMENT

    EPA Science Inventory

    Powdered activated carbon has been the subject of several developmental efforts directed towards producing improved methods for treating municipal wastewaters. Granular activated carbon has proven itself as an effective means of reducing dissolved organic contaminant levels, but ...

  17. Distribution of metal and adsorbed guest species in zeolites

    SciTech Connect

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes {sup 129}Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of {sup 129}Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, {sup 129}Xe NMR is insensitive to fine structural details at room temperature.

  18. Reactions of aqueous glucose solution over solid-acid Y-zeolite catalyst at 110-160 C

    SciTech Connect

    Lourvanij, K.; Rorrer, G.L. )

    1993-01-01

    Reactions of glucose with solid-acid Y-zeolite catalyst were studied to see if this heterogeneous system could produce oxygenated hydrocarbons by shape-selective, acid-catalyzed processes at fairly low temperatures. Experimentally, aqueous solutions of glucose (12 wt %) were reacted with HY-zeolite powder in a well-mixed batch reactor at temperatures ranging from 110 to 160 C and catalyst concentrations ranging from 2 to 20 g/150 ml. Unreacted glucose and oxygenated hydrocarbon products were measured by HPLC as a function of reaction time (0-24 h) and process conditions. Glucose conversions of 100% were obtained at 160 C after an 8-h reaction time. The apparent activation energy based on glucose conversion was 23.25 [plus minus] 0.40 kcal/mol. Several acid-catalyzed reactions were identified, including isomerization of glucose to fructose, partial dehydration of glucose to 5-(hydroxymethyl)furfural (HMF), rehydration and cleavage of HMF to formic acid and 4-oxo-pentanoic acid, and carbonization . Polymers of HMF and seven minor additional products in the lower molecular weight organic acids/aldehydes/ketones elution range were also isolated by HPLC. High yields of organic acids relative to HMF and lowered selectivity of HMF in the bulk phase relative to the homogeneous acid-catalyzed reaction suggests the possibility of molecular sieving reactions within the Y-zeolite in addition to reactions on the outer surface of the Y-zeolite particle.

  19. Factors affecting the behavior of unburned carbon upon steam activation

    NASA Astrophysics Data System (ADS)

    Lu, Zhe

    The main objective of this study is to investigate the factors that could affect the behavior of unburned carbon samples upon steam activation. Through this work, the relationships among the factors that could influence the carbon-steam reaction with the surface area of the produced activated carbon were explored. Statistical analysis was used to relate the chemical and physical properties of the unburned carbon to the surface area of the activated carbon. Six unburned carbons were selected as feedstocks for activated carbon, and marked as UCA through UCF. The unburned carbons were activated using steam at 850°C for 90 minutes, and the surface areas of their activated counterparts were measured using N2 adsorption isotherms at 77K. The activated carbons produced from different unburned carbon precursors presented different surface areas at similar carbon burn-off levels. Moreover, in different carbon burn-off regions, the sequences for surface area of activated carbons from different unburned carbon samples were different. The factors that may affect the carbon-steam gasification reactions, including the concentration of carbon active sites, the crystallite size of the carbon, the intrinsic porous structure of carbon, and the inorganic impurities, were investigated. All unburned carbons investigated in this study were similar in that they showed the very broad (002) and (10 ) carbon peaks, which are characteristic of highly disordered carbonaceous materials. In this study, the unburned carbon samples contained about 17--48% of inorganic impurities. Compared to coals, the unburned carbon samples contain a larger amount of inorganic impurities as a result of the burn-off, or at lease part, of the carbon during the combustion process. These inorganic particles were divided into two groups in terms of the way they are associated with carbon particles: free single particles, and particles combined with carbon particles. As indicated from the present work, unburned

  20. Biodegradation of spilled diesel fuel in agricultural soil: effect of humates, zeolite, and bioaugmentation.

    PubMed

    Kuráň, Pavel; Trögl, Josef; Nováková, Jana; Pilařová, Věra; Dáňová, Petra; Pavlorková, Jana; Kozler, Josef; Novák, František; Popelka, Jan

    2014-01-01

    Possible enhancement of biodegradation of petroleum hydrocarbons in agricultural soil after tank truck accident (~5000 mg/kg dry soil initial concentration) by bioaugmentation of diesel degrading Pseudomonas fluorescens strain and addition of abiotic additives (humates, zeolite) was studied in a 9-month pot experiment. The biodegradation process was followed by means of analytical parameters (hydrocarbon index expressed as content of C10-C40 aliphatic hydrocarbons, ratio pristane/C17, and total organic carbon content) and characterization of soil microbial community (content of phospholipid fatty acids (PLFA) as an indicator of living microbial biomass, respiration, and dehydrogenase activity). The concentration of petroleum hydrocarbons (C10-C40) was successfully reduced by ~60% in all 15 experiment variants. The bioaugmentation resulted in faster hydrocarbon elimination. On the contrary, the addition of humates and zeolite caused only a negligible increase in the degradation rate. These factors, however, affected significantly the amount of PLFA. The humates caused significantly faster increase of the total PLFA suggesting improvement of the soil microenvironment. Zeolite caused significantly slower increase of the total PLFA; nevertheless it aided in homogenization of the soil. Comparison of microbial activities and total PLFA revealed that only a small fraction of autochthonous microbes took part in the biodegradation which confirms that bioaugmentation was the most important treatment. PMID:24672346

  1. Biodegradation of Spilled Diesel Fuel in Agricultural Soil: Effect of Humates, Zeolite, and Bioaugmentation

    PubMed Central

    Kuráň, Pavel; Nováková, Jana; Pilařová, Věra; Dáňová, Petra; Pavlorková, Jana; Kozler, Josef; Novák, František

    2014-01-01

    Possible enhancement of biodegradation of petroleum hydrocarbons in agricultural soil after tank truck accident (~5000 mg/kg dry soil initial concentration) by bioaugmentation of diesel degrading Pseudomonas fluorescens strain and addition of abiotic additives (humates, zeolite) was studied in a 9-month pot experiment. The biodegradation process was followed by means of analytical parameters (hydrocarbon index expressed as content of C10–C40 aliphatic hydrocarbons, ratio pristane/C17, and total organic carbon content) and characterization of soil microbial community (content of phospholipid fatty acids (PLFA) as an indicator of living microbial biomass, respiration, and dehydrogenase activity). The concentration of petroleum hydrocarbons (C10–C40) was successfully reduced by ~60% in all 15 experiment variants. The bioaugmentation resulted in faster hydrocarbon elimination. On the contrary, the addition of humates and zeolite caused only a negligible increase in the degradation rate. These factors, however, affected significantly the amount of PLFA. The humates caused significantly faster increase of the total PLFA suggesting improvement of the soil microenvironment. Zeolite caused significantly slower increase of the total PLFA; nevertheless it aided in homogenization of the soil. Comparison of microbial activities and total PLFA revealed that only a small fraction of autochthonous microbes took part in the biodegradation which confirms that bioaugmentation was the most important treatment. PMID:24672346

  2. REACTION OF ACTIVATED CARBON WITH AQUEOUS CHLORINE AND CHLORINE DIOXIDE

    EPA Science Inventory

    The objective of this research was to determine whether aqueous chlorine and chlorine dioxide react with activated carbon, or with compounds adsorbed on activated carbon, to produce compounds that would not form in the absence of activated carbon. The experimental conditions were...

  3. Less-costly activated carbon for sewage treatment

    NASA Technical Reports Server (NTRS)

    Ingham, J. D.; Kalvinskas, J. J.; Mueller, W. A.

    1977-01-01

    Lignite-aided sewage treatment is based on absorption of dissolved pollutants by activated carbon. Settling sludge is removed and dried into cakes that are pyrolyzed with lignites to yield activated carbon. Lignite is less expensive than activated carbon previously used to supplement pyrolysis yield.

  4. Effect of zinc-bearing zeolite clinoptilolite on growth performance, nutrient retention, digestive enzyme activities, and intestinal function of broiler chickens.

    PubMed

    Tang, Zhigang; Wen, Chao; Li, Ping; Wang, Tian; Zhou, Yanmin

    2014-04-01

    This study was conducted to investigate the effect of zinc-bearing zeolite clinoptilolite (Zn-ZCP) on performance, growth performance, nutrient retention, digestive enzyme activities, and intestinal function in broiler chickens. A total of 180 1-day-old Arbor Acres chickens were randomly divided into three groups with six replicates of ten birds for a 21-day feeding period. Birds were fed a basal corn-soybean meal diet (29.1 mg of Zn per kilogram of diet) without supplemental zinc (control) or the same diet supplemented with 80 mg/kg zinc from ZnSO4 or Zn-ZCP. Zn-ZCP and ZnSO4 treatments had lower feed: gain ratio than that of control group (P < 0.05). Addition of Zn-ZCP increased (P < 0.05) the apparent retention of organic matter and ether extract during 14-17 days, and increased (P < 0.05) pancreatic lipase activity at 14 and 21 days as well as amylase activity at 21 days. Addition of Zn-ZCP increased the villus heights and villus height to crypt depth ratio at the duodenal (P < 0.05) and jejunal (P < 0.05) of broilers at 14 days. Broilers fed the diet supplemented with 80 mg/kg Zn from Zn-ZCP had higher villus heights and villus height to crypt depth ratio of duodenum (P < 0.05) and jejunum (P < 0.05) than those fed with control diet on day 21. Zn-ZCP treatment increased (P < 0.05) IgG and sIgA concentrations in jejunum at 21 days. The results indicated that Zn-ZCP supplementation which might have modified the release of Zn further down in the intestinal tract with the controlled-release characteristic, modulated digestive enzyme activities and intestinal structure and function, increased nutrient retention, and improved feed efficiency. PMID:24515449

  5. Hierarchically structured activated carbon for ultracapacitors

    NASA Astrophysics Data System (ADS)

    Kim, Mok-Hwa; Kim, Kwang-Bum; Park, Sun-Min; Roh, Kwang Chul

    2016-02-01

    To resolve the pore-associated bottleneck problem observed in the electrode materials used for ultracapacitors, which inhibits the transport of the electrolyte ions, we designed hierarchically structured activated carbon (HAC) by synthesizing a mesoporous silica template/carbon composite and chemically activating it to simultaneously remove the silica template and increase the pore volume. The resulting HAC had a well-designed, unique porous structure, which allowed for large interfaces for efficient electric double-layer formation. Given the unique characteristics of the HAC, we believe that the developed synthesis strategy provides important insights into the design and fabrication of hierarchical carbon nanostructures. The HAC, which had a specific surface area of 1,957 m2 g-1, exhibited an extremely high specific capacitance of 157 F g-1 (95 F cc-1), as well as a high rate capability. This indicated that it had superior energy storage capability and was thus suitable for use in advanced ultracapacitors.

  6. Hierarchically structured activated carbon for ultracapacitors

    PubMed Central

    Kim, Mok-Hwa; Kim, Kwang-Bum; Park, Sun-Min; Roh, Kwang Chul

    2016-01-01

    To resolve the pore-associated bottleneck problem observed in the electrode materials used for ultracapacitors, which inhibits the transport of the electrolyte ions, we designed hierarchically structured activated carbon (HAC) by synthesizing a mesoporous silica template/carbon composite and chemically activating it to simultaneously remove the silica template and increase the pore volume. The resulting HAC had a well-designed, unique porous structure, which allowed for large interfaces for efficient electric double-layer formation. Given the unique characteristics of the HAC, we believe that the developed synthesis strategy provides important insights into the design and fabrication of hierarchical carbon nanostructures. The HAC, which had a specific surface area of 1,957 m2 g−1, exhibited an extremely high specific capacitance of 157 F g−1 (95 F cc−1), as well as a high rate capability. This indicated that it had superior energy storage capability and was thus suitable for use in advanced ultracapacitors. PMID:26878820

  7. Chemical interactions in multimetal/zeolite catalysts

    SciTech Connect

    Sachtler, W.M.H.

    1992-02-07

    Mechanistic explanations have been found for the migration of atoms and ions through the zeolite channels leading to specific distribution of ions and the metal clusters. In this report, we summarize the state of understanding attained on a number of topics in the area of mono- and multimetal/zeolite systems, to which our recent research has made significant contributions. The following topics are discussed: (1) Formation of isolated metal atoms in sodalite cages; (2) differences of metal/zeolite systems prepared by ion reduction in channels or via isolated atoms; (3) rejuvenation of Pd/NaY and Pd/HY catalysts by oxidative redispersion of the metal; (4) formation of mono- or bimetal particles in zeolites by programmed reductive decomposition of volatile metal complexes; (5) cation-cation interaction as a cause of enhanced reducibility; (6) formation of palladium carbonyl clusters in supercages; (7) enhanced catalytic activity of metal particle-proton complexes for hydrocarbon conversion reactions; (8) stereoselectivity of catalytic reactions due to geometric constraints of particles in cages.

  8. Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

    NASA Astrophysics Data System (ADS)

    Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

    2014-12-01

    Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

  9. Theoretical study of carbon dioxide activation by metals (Co, Cu, Ni) supported on activated carbon.

    PubMed

    Ha, Nguyen Ngoc; Ha, Nguyen Thi Thu; Van Khu, Le; Cam, Le Minh

    2015-12-01

    The activation of carbon dioxide (CO2) by catalytic systems comprising a transition metal (Co, Cu,Ni) on an activated carbon (AC) support was investigated using a combination of different theoretical calculation methods: Monte Carlo simulation, DFT and DFT-D, molecular dynamics (MD), and a climbing image nudged elastic band (CI-NEB) method. The results obtained indicate that CO2 is easily adsorbed by AC or MAC (M: Cu, Co, Ni). The results also showed that the process of adsorbing CO2 does not involve a transition state, and that NiAC and CoAC are the most effective of the MAC catalysts at adsorbing CO2. Adsorption on NiAC led to the strongest activation of the C-O bond, while adsorption on CuAC led to the weakest activation. Graphical Abstract Models of CO2 activation on: a)- activated carbon; b)- metal supported activated carbon (M-AC), where M: Co, Cu, Ni. PMID:26637187

  10. Vibration damping with active carbon fiber structures

    NASA Astrophysics Data System (ADS)

    Neugebauer, Reimund; Kunze, Holger; Riedel, Mathias; Roscher, Hans-Jürgen

    2007-04-01

    This paper presents a mechatronic strategy for active reduction of vibrations on machine tool struts or car shafts. The active structure is built from a carbon fiber composite with embedded piezofiber actuators that are composed of piezopatches based on the Macro Fiber Composite (MFC) technology, licensed by NASA and produced by Smart Material GmbH in Dresden, Germany. The structure of these actuators allows separate or selectively combined bending and torsion, meaning that both bending and torsion vibrations can be actively absorbed. Initial simulation work was done with a finite element model (ANSYS). This paper describes how state space models are generated out of a structure based on the finite element model and how controller codes are integrated into finite element models for transient analysis and the model-based control design. Finally, it showcases initial experimental findings and provides an outlook for damping multi-mode resonances with a parallel combination of resonant controllers.

  11. Design and characterization of chitosan/zeolite composite films--Effect of zeolite type and zeolite dose on the film properties.

    PubMed

    Barbosa, Gustavo P; Debone, Henrique S; Severino, Patrícia; Souto, Eliana B; da Silva, Classius F

    2016-03-01

    Chitosan films can be used as wound dressings for the treatment of chronic wounds and severe burns. The antimicrobial properties of these films may be enhanced by the addition of silver. Despite the antimicrobial activity of silver, several studies have reported the cytotoxicity as a factor limiting its biomedical applications. This problem may, however, be circumvented by the provision of sustained release of silver. Silver zeolites can be used as drug delivery platforms to extend the release of silver. The objective of this study was to evaluate the addition of clinoptilolite and A-type zeolites in chitosan films. Sodium zeolites were initially subjected to ion-exchange in a batch reactor. Films were prepared by casting technique using a 2% w/w chitosan solution and two zeolite doses (0.1 or 0.2% w/w). Films were characterized by thermal analysis, color analysis, scanning electron microscopy, X-ray diffraction, and water vapor permeation. The results showed that films present potential for application as dressing. The water vapor permeability is one of the main properties in wound dressings, the best results were obtained for A-type zeolite/chitosan films, which presented a brief reduction of this property in relation to zeolite-free chitosan film. On the other hand, the films containing clinoptilolite showed lower water vapor permeation, which may be also explained by the best distribution of the particles into the polymer which also promoted greater thermal resistance. PMID:26706528

  12. Zeolite exposure and associated pneumoconiosis

    SciTech Connect

    Casey, K.R.; Shigeoka, J.W.; Rom, W.N.; Moatamed, F.

    1985-06-01

    Naturally occurring zeolite minerals are aluminum silicates widespread in the earth's crust. Several of these minerals have fibrous forms and have been implicated as a possible cause of benign and malignant diseases of the lung and pleura in Turkey. This report describes a patient, living in an area of Nevada rich in zeolites, who presented with idiopathic pleural thickening and pulmonary fibrosis associated with extensive pulmonary deposition of zeolites.

  13. Disilane-modified mordenite zeolites

    SciTech Connect

    Yan, Y.; Vansant, E.F. )

    1990-03-22

    The effective pore size of H-mordenite zeolite can be decreased by implantation of disilyl compounds. Chemisorption of disilane at high temperature results in denser packing of the implanted entities on the external surface. This in turn enhances the pore narrowing effect. After hydrolysis-dehydration, the external surface of the disilanated zeolite can be reactivated by partial rehydration; thus a successive modification of the zeolite surface is possible.

  14. Adsorbed natural gas storage with activated carbon

    SciTech Connect

    Sun, Jian; Brady, T.A.; Rood, M.J.

    1996-12-31

    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.

  15. Charcoal and activated carbon at elevated pressure

    SciTech Connect

    Antal, M.J. Jr.; Dai, Xiangfeng; Norberg, N.

    1995-12-01

    High quality charcoal has been produced with very high yields of 50% to 60% from macadamia nut and kukui nut shells and of 44% to 47% from Eucalyptus and Leucaena wood in a bench scale unit at elevated pressure on a 2 to 3 hour cycle, compared to commercial practice of 25% to 30% yield on a 7 to 12 day operating cycle. Neither air pollution nor tar is produced by the process. The effects of feedstock pretreatments with metal additives on charcoal yield are evaluated in this paper. Also, the influences of steam and air partial pressure and total pressure on yields of activated carbon from high yield charcoal are presented.

  16. Catalytic desulfurization of organic sulfur compounds over zeolite catalysts

    SciTech Connect

    Sugioka, M.; Aomura, K.

    1980-03-01

    Various kinds of zeolites, such as Na-zeolites, MeY and HY, showed catalytic activity for the dehydrosulfurization of ethanethiol. The catalytic activity of MeY in the dehydrosulfurization of ethanethiol at 400/sup 0/C was changed by the kind of metal ions in the zeolites and a volcano shape order was observed between the catalytic activity and the electronegativity, Xi, of the metal ions. The order of the catalytic activity was NaX>NaY>NaA. The changes in the activity of HY in ethanethiol dehydrosulfurization and cumene dealkylation by calcination agreed with the decrease in the Bronsted acidity determined by Ward but was independent of Lewis acidity. Me/sup 0/Y, such as Co/sup 0/Y, Ni/sup 0/Y, Cu/sup 0/Y and Ag/sup 0/Y, showed higher catalytic activity than a commercial hydrodesulfurization catalyst and the order of the activity was Ni/sup 0/Y>Co/sup 0/Y>Cu/sup 0/Y>Ag/sup 0/Y. Reduced and presulfided Me/sup 0/Y zeolites showed selective hydrodesulfurization activity for thiophene. The remarkable promoting effect of NiO and MoO/sub 3/ upon the catalytic activity of Me/sup 0/Y was not observed in the hydrodesulfurization of thiophene. Zeolite catalysts have a possibility of use as effective hydrodesulfurization catalysts for petroleum if further improvement in catalyst deactivation of Me/sup 0/Y zeolite is accomplished. The investigation of the hydrodesulfurization of thiophene over Me/sup 0/Y zeolites would become a good model to clarify the mechanism of the hydrodesulfurization of petroleum.

  17. Bactericidal activity and silver release of porous ceramic candle filter prepared by sintering silica with silver nanoparticles/zeolite for water disinfection

    NASA Astrophysics Data System (ADS)

    Trinh Nguyen, Thuy Ai; Phu Dang, Van; Duy Nguyen, Ngoc; Le, Anh Quoc; Thanh Nguyen, Duc; Hien Nguyen, Quoc

    2014-09-01

    Porous ceramic candle filters (PCCF) were prepared by sintering silica from rice husk with silver nanoparticles (AgNPs)/zeolite A at about 1050 °C to create bactericidal PCCF/AgNPs for water disinfection. The silver content in PCCF/AgNPs was of 300-350 mg kg-1 determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and the average pore size of PCCF/AgNPs was of 50-70 Å measured by Brunauer-Emmett-Teller (BET) method. The bactericidal activity and silver release of PCCF/AgNPs have been investigated by flow test with water flow rate of 5 L h-1 and initial inoculation of E. coli in inlet water of 106 CFU/100 mL. The volume of filtrated water was collected up to 500 L. Results showed that the contamination of E. coli in filtrated water was <1 CFU/100 mL and the content of silver released from PCCF/AgNPs into filtrated water was <1 μg L-1, it is low, far under the WHO guideline of 100 μg L-1 at maximum for drinking water. Based on the content of silver in PCCF/AgNPs and in filtrated water, it was estimated that one PCCF/AgNPs could be used to filtrate of ˜100 m3 water. Thus, as-prepared PCCF/AgNPs releases low content of silver into water and shows effectively bactericidal activity that is promising to apply as point-of-use water treatment technology for drinking water disinfection.

  18. Production of activated carbon from TCR char

    NASA Astrophysics Data System (ADS)

    Stenzel, Fabian; Heberlein, Markus; Klinner, Tobias; Hornung, Andreas

    2016-04-01

    The utilization of char for adsorptive purposes is known since the 18th century. At that time the char was made of wood or bones and used for decoloration of fluids. In the 20th century the production of activated carbon in an industrial scale was started. The today's raw materials for activated carbon production are hard coal, peat, wood or coconut shells. All these materials entail costs especially the latter. Thus, the utilization of carbon rich residues (biomass) is an interesting economic opportunity because it is available for no costs or even can create income. The char is produced by thermo-catalytic reforming (TCR®). This process is a combination of an intermediate pyrolysis and subsequently a reforming step. During the pyrolysis step the material is decomposed in a vapor and a solid carbon enriched phase. In the second step the vapor and the solid phase get in an intensive contact and the quality of both materials is improved via the reforming process. Subsequently, the condensables are precipitated from the vapor phase and a permanent gas as well as oil is obtained. Both are suitable for heat and power production which is a clear advantage of the TCR® process. The obtained biochar from the TCR® process has special properties. This material has a very low hydrogen and oxygen content. Its stability is comparable to hard coal or anthracite. Therefore it consists almost only of carbon and ash. The latter depends from input material. Furthermore the surface structure and area can be influenced during the reforming step. Depending from temperature and residence time the number of micro pores and the surface area can be increased. Preliminary investigations with methylene blue solution have shown that a TCR® char made of digestate from anaerobic digestion has adsorptive properties. The decoloration of the solution was achieved. A further influencing factor of the adsorption performance is the particle size. Based on the results of the preliminary tests a

  19. Influence of NaA Zeolite Crystal Expansion/Contraction on Zeolite Membrane Separations

    SciTech Connect

    Sorenson, Stephanie G; Payzant, E Andrew; Gibbons, Will T; Soydas, Belma; Kita, Hidetoshi; Noble, Richard D; Falconer, John L.

    2011-01-01

    In-situ powder XRD measurements showed that the NaA zeolite unit cell contracts and expands upon adsorption, and these changes in zeolite crystal size correlate with permeation changes through NaA zeolite membranes. These membranes had high pervaporation selectivities, even though gas permeation was mainly through defects, as indicated by Knudsen selectivities for gases. At 300 K and a thermodynamic activity of 0.03, water contracted the NaA crystals by 0.22 vol%, and this contraction increased the helium flux through two NaA membranes by approximately 80%. Crystal contraction also increased the fluxes of i-butane during vapor permeation and i-propanol (IPA) during pervaporation (~ 0.03 wt% water). At activities above 0.07, water expanded NaA crystals and correspondingly decreased the membrane fluxes of helium, i-butane, and IPA. Similarly, methanol contracted NaA crystals by 0.05 vol% at an activity of 0.02, and this contraction slightly increased the helium and i-butane fluxes through a NaA membrane. Above an activity of 0.06, methanol expanded the crystals, and the fluxes of helium and i-butane through a NaA membrane decreased. The adsorbate-induced changes explain some pervaporation behavior reported by others, and they indicate that crystal expansion and contraction may increase or decrease zeolite NaA membrane selectivity by changing the defect sizes.

  20. The stability of copper oxo species in zeolite frameworks

    DOE PAGESBeta

    Vilella, Laia; Studt, Felix

    2016-03-07

    Cu-exchanged zeolites are promising heterogeneous catalysts, as they provide a confined environment to carry out highly selective reactions. Furthermore, the knowledge of how the zeolite framework and the location of Al atoms therein affect the adsorption of copper species is still not well understood. In this work, DFT was used to investigate the adsorption of potential Cu oxo active species suggested in the literature [Cu(η2-O2), Cu(µ-O)Cu, and Cu2O2] into zeolites with different pore sizes and shapes (AFI, CHA, TON, MOR, and MFI). The calculations revealed that both monomeric and dimeric Cu oxo species bind strongly to the O atoms ofmore » the lattice. For the monometallic species similar adsorption energies are obtained with the different zeolite frameworks, whereas an optimum Al–Al distance is required for the dimeric species.« less

  1. The regeneration of polluted activated carbon by radiation techniques

    NASA Astrophysics Data System (ADS)

    Minghong, Wu; Borong, Bao; Ruimin, Zhou; Jinliang, Zhu; Longxin, Hu

    1998-10-01

    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

  2. Preparation of binderless activated carbon monolith from pre-carbonization rubber wood sawdust by controlling of carbonization and activation condition

    NASA Astrophysics Data System (ADS)

    Taer, E.; Deraman, M.; Taslim, R.; Iwantono

    2013-09-01

    Binderless activated carbon monolith (ACM) was prepared from pre-carbonized rubber wood sawdust (RWSD). The effect of the carbonization temperature (400, 500, 600, 700, 800 dan 900 °C) on porosity characteristic of the ACM have been studied. The optimum carbonization temperature for obtaining ACM with high surface area of 600 °C with CO2 activation at 800 °C for one hour. At this condition, the surface area as high as 733 m2 g-1 could be successfully obtained. By improved the activation temperature at 900 °C for 2.5 h, it was found that the surface area of 860 m2 g-1. For this condition, the ACM exhibit the specific capacitance of 90 F g-1. In addition the termogravimertic (TG)-differential termografimertic (DTG) and field emission scanning electron microscope (FESEM) measurement were also performed on the ACMs and the result has been studied. Finally, it was conclude that the high surface area of ACM from RWSD could be produced by proper selections of carbonization and activation condition.

  3. Plant diversity increases soil microbial activity and soil carbon storage.

    PubMed

    Lange, Markus; Eisenhauer, Nico; Sierra, Carlos A; Bessler, Holger; Engels, Christoph; Griffiths, Robert I; Mellado-Vázquez, Perla G; Malik, Ashish A; Roy, Jacques; Scheu, Stefan; Steinbeiss, Sibylle; Thomson, Bruce C; Trumbore, Susan E; Gleixner, Gerd

    2015-01-01

    Plant diversity strongly influences ecosystem functions and services, such as soil carbon storage. However, the mechanisms underlying the positive plant diversity effects on soil carbon storage are poorly understood. We explored this relationship using long-term data from a grassland biodiversity experiment (The Jena Experiment) and radiocarbon ((14)C) modelling. Here we show that higher plant diversity increases rhizosphere carbon inputs into the microbial community resulting in both increased microbial activity and carbon storage. Increases in soil carbon were related to the enhanced accumulation of recently fixed carbon in high-diversity plots, while plant diversity had less pronounced effects on the decomposition rate of existing carbon. The present study shows that elevated carbon storage at high plant diversity is a direct function of the soil microbial community, indicating that the increase in carbon storage is mainly limited by the integration of new carbon into soil and less by the decomposition of existing soil carbon. PMID:25848862

  4. Lithium modified zeolite synthesis for conversion of biodiesel-derived glycerol to polyglycerol

    SciTech Connect

    Ayoub, Muhammad; Abdullah, Ahmad Zuhairi; Inayat, Abrar

    2014-10-24

    Basic zeolite has received significant attention in the catalysis community. These zeolites modified with alkaline are the potential replacement for existing zeolite catalysts due to its unique features with added advantages. The present paper covers the preparation of lithium modified zeolite Y (Li-ZeY) and its activity for solvent free conversion of biodiesel-derived glycerol to polyglycerol via etherification process. The modified zeolite was well characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Nitrogen Adsorption. The SEM images showed that there was no change in morphology of modified zeolite structure after lithium modification. XRD patterns showed that the structure of zeolite was sustained after lithium modification. The surface properties of parent and modified zeolite was also observed N{sub 2} adsortion-desorption technique and found some changes in surface area and pore size. In addition, the basic strength of prepared materials was measured by Hammet indicators and found that basic strength of Li-ZeY was highly improved. This modified zeolite was found highly thermal stable and active heterogamous basic catalyst for conversion of solvent free glycerol to polyglycerol. This reaction was conducted at different temperatures and 260 °C was found most active temperature for this process for reaction time from 6 to 12 h over this basic catalyst in the absence of solvent.

  5. Lithium modified zeolite synthesis for conversion of biodiesel-derived glycerol to polyglycerol

    NASA Astrophysics Data System (ADS)

    Ayoub, Muhammad; Abdullah, Ahmad Zuhairi; Inayat, Abrar

    2014-10-01

    Basic zeolite has received significant attention in the catalysis community. These zeolites modified with alkaline are the potential replacement for existing zeolite catalysts due to its unique features with added advantages. The present paper covers the preparation of lithium modified zeolite Y (Li-ZeY) and its activity for solvent free conversion of biodiesel-derived glycerol to polyglycerol via etherification process. The modified zeolite was well characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Nitrogen Adsorption. The SEM images showed that there was no change in morphology of modified zeolite structure after lithium modification. XRD patterns showed that the structure of zeolite was sustained after lithium modification. The surface properties of parent and modified zeolite was also observed N2 adsortion-desorption technique and found some changes in surface area and pore size. In addition, the basic strength of prepared materials was measured by Hammet indicators and found that basic strength of Li-ZeY was highly improved. This modified zeolite was found highly thermal stable and active heterogamous basic catalyst for conversion of solvent free glycerol to polyglycerol. This reaction was conducted at different temperatures and 260 °C was found most active temperature for this process for reaction time from 6 to 12 h over this basic catalyst in the absence of solvent.

  6. 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...

  7. DISINFECTION OF BACTERIA ATTACHED TO GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    Heterotrophic plate count bacteria, coliform organisms, and pathogenic microorganisms attached to granular activated carbon (GAC) particles were examined for their susceptibility to chlorine disinfection. When these bacteria were grown on carbon particles and then disinfected wit...

  8. Potential and challenges of zeolite chemistry in the catalytic conversion of biomass.

    PubMed

    Ennaert, Thijs; Van Aelst, Joost; Dijkmans, Jan; De Clercq, Rik; Schutyser, Wouter; Dusselier, Michiel; Verboekend, Danny; Sels, Bert F

    2016-02-01

    Increasing demand for sustainable chemicals and fuels has pushed academia and industry to search for alternative feedstocks replacing crude oil in traditional refineries. As a result, an immense academic attention has focused on the valorisation of biomass (components) and derived intermediates to generate valuable platform chemicals and fuels. Zeolite catalysis plays a distinct role in many of these biomass conversion routes. This contribution emphasizes the progress and potential in zeolite catalysed biomass conversions and relates these to concepts established in existing petrochemical processes. The application of zeolites, equipped with a variety of active sites, in Brønsted acid, Lewis acid, or multifunctional catalysed reactions is discussed and generalised to provide a comprehensive overview. In addition, the feedstock shift from crude oil to biomass involves new challenges in developing fields, like mesoporosity and pore interconnectivity of zeolites and stability of zeolites in liquid phase. Finally, the future challenges and perspectives of zeolites in the processing of biomass conversion are discussed. PMID:26691750

  9. XAFS Study on TiO2 Photocatalyst Loaded on Zeolite Synthesized from Steel Slag

    SciTech Connect

    Kuwahara, Yasutaka; Ohmichi, Tetsutaro; Mori, Kosuke; Katayama, Iwao; Yamashita, Hiromi

    2007-02-02

    The convenient route for the synthesis of Y-zeolites by utilizing steel slag as a material source was developed. Through hydrothermal treatment, well-crystallized Y-zeolite was obtained. We also synthesized TiO2-loaded Y-zeolites by an impregnation method. The structure of titanium oxide species highly dispersed on the zeolite, which couldn't be detected by XRD patterns, was investigated by XAFS analysis. Photocatalytic activity for decomposition of 2-propanol in liquid phase was found to be enhanced by the hydrophobic surface property of zeolite. It has been demonstrated that the zeolite synthesized from steel slag would be applicable as a promising support of TiO2 photocatalyst.

  10. 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...

  11. Simultaneous realization of high catalytic activity and stability for catalytic cracking of n-heptane on highly exposed (010) crystal planes of nanosheet ZSM-5 zeolite.

    PubMed

    Xiao, Xia; Zhang, Yaoyuan; Jiang, Guiyuan; Liu, Jia; Han, Shanlei; Zhao, Zhen; Wang, Ruipu; Li, Cong; Xu, Chunming; Duan, Aijun; Wang, Yajun; Liu, Jian; Wei, Yuechang

    2016-08-01

    Nanosheet ZSM-5 zeolite with highly exposed (010) crystal planes demonstrates high reactivity and good anti-coking stability for the catalytic cracking of n-heptane, which is attributed to the synergy of high external surface area and acid sites, fully accessible channel intersection acid sites, and hierarchical porosity caused by the unique morphology. PMID:27458616

  12. Preparation and gas separation properties of zeolite T membrane.

    PubMed

    Cui, Ying; Kita, Hidetoshi; Okamoto, Ken-ichi

    2003-09-01

    Zeolite T membranes were synthesized on tubular porous mullite tubes by hydrothermal synthesis. The membranes selectively permeated carbon dioxide from CO2/CH4 and CO2/N2 mixtures with high separation performances, which were due to combined effects of molecular sieving and competitive adsorption. PMID:13678177

  13. DEVELOPMENT OF ACTIVATED CARBONS FROM COAL COMBUSTION BY-PRODUCTS

    SciTech Connect

    Harold H. Schobert; M. Mercedes Maroto-Valer; Zhe Lu

    2003-09-30

    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

  14. Thermal behavior of natural zeolites

    SciTech Connect

    Bish, D.L.

    1993-09-01

    Thermal behavior of natural zeolites impacts their application and identification and varies significantly from zeolite to zeolite. Zeolites evolve H{sub 2}0 upon heating, but recent data show that distinct ``types`` of water (e.g., loosely bound or tightly bound zeolitic water) do not exist. Rather water is bound primarily to extra-framework cations with a continuum of energies, giving rise to pseudocontinuous loss of water accompanied by a dynamic interaction between remaining H{sub 2}0 molecules and extra-framework cations. These interactions in the channels of zeolites give rise to dehydration dependent on the extra-framework cation, in addition to temperature and water vapor pressure. The dehydration reaction and the extra-framework cation also affect the thermal expansion/contraction. Most zeolites undergo dehydration-induced contractions that may be anisotropic, although minor thermal expansion can be seen with some zeolites. Such contractions can be partially or completely irreversible if they involve modifications of the tetrahedral framework and/or if rehydration is sluggish. Thermally induced structural modifications are also driven initially by dehydration and the concomitant contraction and migration of extra-framework cations. Contraction is accommodated by rotations of structural units and tetrahedral cation-oxygen linkages may break. Thermal reactions that involve breaking of tetrahedral cation-oxygen bonds markedly irreversible and may be kinetically limited, producing large differences between short- and long-term heating.

  15. Characterization of lead sorption by the natural and Fe(III)-modified zeolite

    NASA Astrophysics Data System (ADS)

    Kragović, Milan; Daković, Aleksandra; Marković, Marija; Krstić, Jugoslav; Gatta, G. Diego; Rotiroti, Nicola

    2013-10-01

    The influence of contact time, temperature and particle size on lead sorption by the natural and Fe(III)-modified zeolites was investigated. Characterization of the natural and Fe(III)-modified zeolite before and after lead sorption was performed by determination of textural properties, by scanning electron microscopy and X-ray spectroscopy in energy-dispersive mode (SEM-EDS), transmission electron microscopy (TEM) and X-ray powder diffraction (XRPD) analysis. Lead sorption kinetics at 303-333 K, best represented by the pseudo-second order model and activation energy (13.5 and 8.5 kJ/mol for the natural and Fe(III)-modified zeolite respectively) confirmed an activated chemical sorption. Desorption experiments indicated that lead was irreversibly sorbed on both zeolites. XRPD, TEM and SEM results showed that modification of the natural zeolite with Fe(III) ions did not change its crystal structure and iron is mainly located at the zeolite surface, likely in form of amorphous iron oxy-hydroxides. Specific surface area significantly increases after modification of the natural zeolite with Fe(III) ions (from 30.2 for the natural to 52.5 m2/g for Fe(III)-modified zeolite). Characterization of both lead saturated sorbents suggested that besides ion exchange, lead is both chemisorbed and precipitated at their surfaces, and presence of amorphous iron in Fe(III)-modified zeolite favors sorption of lead.

  16. Metal-carbon nanocomposites based on activated IR pyrolized polyacrylonitrile

    NASA Astrophysics Data System (ADS)

    Efimov, Mikhail N.; Zhilyaeva, Natalya A.; Vasilyev, Andrey A.; Muratov, Dmitriy G.; Zemtsov, Lev M.; Karpacheva, Galina P.

    2016-05-01

    In this paper we report about new approach to preparation of metal-carbon nanocomposites based on activated carbon. Polyacrylonitrile is suggested as a precursor for Co, Pd and Ru nanoparticles carbon support which is prepared under IR pyrolysis conditions of a precursor. The first part of the paper is devoted to study activated carbon structural characteristics dependence on activation conditions. In the second part the effect of type of metal introduced in precursor on metal-carbon nanocomposite structural characteristics is shown. Prepared AC and nanocomposite samples are characterized by BET, TEM, SEM and X-ray diffraction.

  17. First Principles Simulations of Hydrocarbon Conversion Processes in Functionalized Zeolitic Materials

    NASA Astrophysics Data System (ADS)

    Mazar, Mark Nickolaus

    is responsible for the largest activation energy of the catalytic cycle. This assessment is similar to the findings of alkane metathesis studies on alumina/silica supports and indicates that the entire AM cycle can be performed in zeolites by isolated single-atom transition metal hydrides. Performed over acid form zeolites, MTH is used in the conversion of methanol into a broad range of hydrocarbons, including alkenes, alkanes, and aromatics. For reasons that are not yet rigorously quantified, product selectivities vary dramatically based on the choice of catalyst and reaction conditions. The methylation of species containing double bonds (i.e., co-catalysts) is central to the overall process. Distinct structure-function relationships were found with respect to the elementary steps in the methylation and beta-scission of olefins. In Chapter 4, the role of zeolite topology in the step-wise methylation of ethene by surface methoxides is investigated. Elementary steps are studied across multiple frameworks (i.e., BEA, CHA, FER, MFI, and MOR) constituting a wide variety of confinement environments. The reaction of surface methoxides with ethene is found to require a transition state containing a primary carbocation. The barrier height is found to decrease nearly monotonically with respect to the degree of dispersion interactions stabilizing the primary carbocationic species in the transition state. In addition, quantification of the ``local'' dispersion energy indicates that confinement effects can not be simply correlated to pore size. The beta-scission of olefins plays an important role in the product selectivities of many important chemical processes, including MTH. In Chapter 5, beta-scission modes involving C6 and C8 isomers are investigated at a single, isolated Bronsted acid site within H-ZSM-5. We find that the relative enthalpic barriers of beta-scission elementary steps can be rationalized by the substitution order of the two different carbocationic carbon

  18. Merging allylic carbon-hydrogen and selective carbon-carbon bond activation

    NASA Astrophysics Data System (ADS)

    Masarwa, Ahmad; Didier, Dorian; Zabrodski, Tamar; Schinkel, Marvin; Ackermann, Lutz; Marek, Ilan

    2014-01-01

    Since the nineteenth century, many synthetic organic chemists have focused on developing new strategies to regio-, diastereo- and enantioselectively build carbon-carbon and carbon-heteroatom bonds in a predictable and efficient manner. Ideal syntheses should use the least number of synthetic steps, with few or no functional group transformations and by-products, and maximum atom efficiency. One potentially attractive method for the synthesis of molecular skeletons that are difficult to prepare would be through the selective activation of C-H and C-C bonds, instead of the conventional construction of new C-C bonds. Here we present an approach that exploits the multifold reactivity of easily accessible substrates with a single organometallic species to furnish complex molecular scaffolds through the merging of otherwise difficult transformations: allylic C-H and selective C-C bond activations. The resulting bifunctional nucleophilic species, all of which have an all-carbon quaternary stereogenic centre, can then be selectively derivatized by the addition of two different electrophiles to obtain more complex molecular architecture from these easily available starting materials.

  19. Activated Carbon Composites for Air Separation

    SciTech Connect

    Baker, Frederick S; Contescu, Cristian I; Tsouris, Costas; Burchell, Timothy D

    2011-09-01

    Coal-derived synthesis gas is a potential major source of hydrogen for fuel cells. Oxygen-blown coal gasification is an efficient approach to achieving the goal of producing hydrogen from coal, but a cost-effective means of enriching O2 concentration in air is required. A key objective of this project is to assess the utility of a system that exploits porous carbon materials and electrical swing adsorption to produce an O2-enriched air stream for coal gasification. As a complement to O2 and N2 adsorption measurements, CO2 was used as a more sensitive probe molecule for the characterization of molecular sieving effects. To further enhance the potential of activated carbon composite materials for air separation, work was implemented on incorporating a novel twist into the system; namely the addition of a magnetic field to influence O2 adsorption, which is accompanied by a transition between the paramagnetic and diamagnetic states. The preliminary findings in this respect are discussed.

  20. Synthesis and characterization of nanocrystalline and mesoporous zeolites

    NASA Astrophysics Data System (ADS)

    Petushkov, Anton

    2011-12-01

    Mesoporous aggregates of nanocrystalline zeolites with MFI and BEA frameworks have been synthesized using a one-pot and single structure directing agent. The effect of different reaction conditions, such as temperature, time, pH and water content, on the particle size, surface area and mesopore volume has been studied. Nanocrystalline and mesoporous ZSM-5, beta and Y zeolites were modified with different transition metals and the resulting single- and double metal containing catalyst materials were characterized. Nanocrystalline Silicalite-1 zeolite samples with varying particle size were functionalized with different organosilane groups and the cytotoxic activity of the zeolite nanocrystals was studied as a function of particle size, concentration, organic functional group type, as well as the type of cell line. Framework stability of nanocrystalline NaY zeolite was tested under different pH conditions. The synthesized zeolites used in this work were characterized using a variety of physico-chemical methods, including powder X-ray diffraction, Solid State NMR, nitrogen sorption, electron microscopy, Inductively Coupled Plasma -- Optical Emission Spectroscopy and X-ray Photoelectron Spectroscopy.

  1. Characterization of Chemical Properties, Unit Cell Parameters and Particle Size Distribution of Three Zeolite Reference Materials: RM 8850 - Zeolite Y, RM 8851 - Zeolite A and RM 8852 - Ammonium ZSM-5 Zeolite

    SciTech Connect

    Turner,S.; Sieber, J.; Vetter, T.; Zeisler, R.; Marlow, A.; Moreno-Ramirez, M.; Davis, M.; Kennedy, G.; Borghard, W.; et al

    2008-01-01

    Zeolites have important industrial applications including use as catalysts, molecular sieves and ion exchange materials. In this study, three zeolite materials have been characterized by the National Institute of Standards and Technology (NIST) as reference materials (RMs): zeolite Y (RM 8850), zeolite A (RM 8851) and ZSM-5 zeolite (RM 8852). They have been characterized by a variety of chemical and physical measurement methods: X-ray fluorescence (XRF), gravimetry, instrumental neutron activation analysis (INAA), nuclear magnetic resonance (NMR), calorimetry, synchrotron X-ray diffraction, neutron diffraction, laser light extinction, laser light scattering, electric sensing zone, X-ray sedimentation, scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM) and optical microscopy. The chemical homogeneity of the materials has been characterized. Reference values are given for the major components (major elements, loss on ignition [LOI] and loss on fusion [LOF]), trace elements and Si/Al and Na/Al ratios. Information values are given for enthalpies of formation, unit cell parameters, particle size distributions, refractive indices and variation of mass with variation in relative humidity (RH). Comparisons are made to literature unit cell parameters. The RMs are expected to provide a basis for intercomparison studies of these zeolite materials.

  2. Dealumination of zeolite {beta} via dicarboxylic acid treatment

    SciTech Connect

    Apelian, M.R.; Fung, A.S.; Kennedy, G.J.; Degnan, T.F.

    1996-10-10

    It is demonstrated that zeolite {beta} and zeolite {beta} containing catalysts can be dealuminated to very low acidity levels using a novel oxalic acid treatment without reducing zeolite integrity. The effect of the oxalic acid treatment has been studied over a wide range of treatment conditions for both silica-bound and unbound zeolite {beta} catalysts. Greater than 90% dealumination is observed with a concomitant reduction in n-hexane-cracking activity as measured by the alpha ({alpha}) test. Removal of framework aluminum occurs via a two-step hyrolysis/chelation mechanism, with the oxalic acid acting both as an acid and as a chelating agent. Framework aluminum removal is accompanied by the formation of internal silanol groups. Water soluble aluminum oxalates are present in the extracted solutions. Silanol groups are annealed with extended oxalic acid treatment. Oxalic acid treatment results in a unique contraction of the zeolite {beta} lattice structure not observed for mineral acid treated or steamed zeolite {beta} catalysts. 15 refs., 11 figs., 5 tabs.

  3. Adamantanes from petroleum, with zeolites

    SciTech Connect

    Rollmann, L.D.; Green, L.A.; Bradway, R.A.

    1995-12-31

    Experiments with zeolite Beta and zeolite {Upsilon} demonstrate that adamantane and methyl adamantanes can be isolated very effectively from modern refinery streams by mild hydrocracking over Pt- and Pd-containing large pore zeolites. Yield depends importantly on individual refinery crude source and process configuration. Heavy crudes and refineries with conventional hydrocracking and FCC feed hydrotreater facilities are particularly desirable, and an ideal feed for adamantane isolation in such a situation is the 150{degrees}-250{degrees}C fraction of the hydrocracker (HDC) recycle stream. When Pt- or Pd-containing zeolite Beta was used with such a stream, temperatures of some 250{degrees}C and pressures below 3.5 mPa (500 psig) sufficed to remove selectively well over 90% of the non-adamantane hydrocarbon, with little conversion of adamantanes. High selectivity for adamantanes is attributed in large part to size-selective exclusion of these molecules from the pores of zeolite Beta.

  4. Highly porous activated carbons prepared from carbon rich Mongolian anthracite by direct NaOH activation

    NASA Astrophysics Data System (ADS)

    Byamba-Ochir, Narandalai; Shim, Wang Geun; Balathanigaimani, M. S.; Moon, Hee

    2016-08-01

    Highly porous activated carbons (ACs) were prepared from Mongolian raw anthracite (MRA) using sodium hydroxide as an activation agent by varying the mass ratio (powdered MRA/NaOH) as well as the mixing method of chemical agent and powdered MRA. The specific BET surface area and total pore volume of the prepared MRA-based activated carbons (MACs) are in the range of 816-2063 m2/g and of 0.55-1.61 cm3/g, respectively. The pore size distribution of MACs show that most of the pores are in the range from large micropores to small mesopores and their distribution can be controlled by the mass ratio and mixing method of the activating agent. As expected from the intrinsic property of the MRA, the highly graphitic surface morphology of prepared carbons was confirmed from Raman spectra and transmission electron microscopy (TEM) studies. Furthermore the FTIR and XPS results reveal that the preparation of MACs with hydrophobic in nature is highly possible by controlling the mixing conditions of activating agent and powdered MRA. Based on all the results, it is suggested that the prepared MACs could be used for many specific applications, requiring high surface area, optimal pore size distribution, proper surface hydrophobicity as well as strong physical strength.

  5. Discovery of optimal zeolites for challenging separations and chemical transformations using predictive materials modeling

    NASA Astrophysics Data System (ADS)

    Bai, Peng; Jeon, Mi Young; Ren, Limin; Knight, Chris; Deem, Michael W.; Tsapatsis, Michael; Siepmann, J. Ilja

    2015-01-01

    Zeolites play numerous important roles in modern petroleum refineries and have the potential to advance the production of fuels and chemical feedstocks from renewable resources. The performance of a zeolite as separation medium and catalyst depends on its framework structure. To date, 213 framework types have been synthesized and >330,000 thermodynamically accessible zeolite structures have been predicted. Hence, identification of optimal zeolites for a given application from the large pool of candidate structures is attractive for accelerating the pace of materials discovery. Here we identify, through a large-scale, multi-step computational screening process, promising zeolite structures for two energy-related applications: the purification of ethanol from fermentation broths and the hydroisomerization of alkanes with 18-30 carbon atoms encountered in petroleum refining. These results demonstrate that predictive modelling and data-driven science can now be applied to solve some of the most challenging separation problems involving highly non-ideal mixtures and highly articulated compounds.

  6. Characterization of Activated Carbons from Oil-Palm Shell by CO2 Activation with No Holding Carbonization Temperature

    PubMed Central

    Herawan, S. G.; Hadi, M. S.; Ayob, Md. R.; Putra, A.

    2013-01-01

    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

  7. Recovery of oxygenated ignitable liquids by zeolites, Part I: Novel extraction methodology in fire debris analysis.

    PubMed

    St Pierre, Kathryne A; Desiderio, Vincent J; Hall, Adam B

    2014-07-01

    The recovery of low molecular weight oxygenates in fire debris samples is severely compromised by the use of heated passive headspace concentration with an activated charcoal strip, as outlined in ASTM E-1412. The term "oxygenate" is defined herein as a small, polar, organic molecule, such as acetone, methanol, ethanol, or isopropanol, which can be employed as an ignitable liquid and referred to in the ASTM classification scheme as the "oxygenated solvents" class. Although a well accepted technique, the higher affinity of activated carbon strips for heavy molecular weight products over low molecular weight products and hydrocarbons over oxygenated products, it does not allow for efficient recovery of oxygenates such as low molecular weight alcohols and acetone. The objective of this study was to develop and evaluate a novel method for the enhanced recovery of oxygenates from fire debris samples. By optimizing conditions of the heated passive headspace technique, the utilization of zeolites allowed for the successful collection and concentration of oxygenates. The results demonstrated that zeolites increased the recovery of oxygenates by at least 1.5-fold compared to the activated carbon strip and may complement the currently used extraction technique. PMID:24780556

  8. Chemical Interactions in Multimetal/Zeolite Catalysts

    SciTech Connect

    Sachtler, Wolfgang M. H.

    2004-04-16

    This two-year project has led to a significant improvement in the fundamental understanding of the catalytic action of zeolite-supported redox catalysts. It turned out to be essential that we could combine four strategies for the preparation of catalysts containing transition metal (TM) ions in zeolite cavities: (1) ion exchange from aqueous solution; (2) chemical vapor deposition (CVD) of a volatile halide onto a zeolite in its acidic form; (3) solid state ion exchange; and (4) hydrothermal synthesis of a zeolite having TM ions in its lattice, followed by a treatment transporting these ions to ''guest positions''. Technique (2) enables us to position more TM ions into cavities than permitted by the conventional technique (1).viz one positive charge per Al centered tetrahedron in the zeolite lattice. The additional charge is compensated by ligands to the TM ions, for instance in oxo-ions such as (GaO){sup +} or dinuclear [Cu-O-Cu]{sup 2+}. While technique (3) is preferred over CVD where volatile halides are not available, technique (4) leads to rather isolated ''ex lattice'' oxo-ions. Such oxo-ions tend to be mono-nuclear, in contrast to technique (2) which preferentially creates dinuclear oxo-ions of the same TM element. A favorable element for the present research was that the PI is also actively engaged in a project on the reduction of nitrogen oxides, sponsored by EMSI program of the National Science Foundation and the US Department of Energy, Office of Science. This combination created a unique opportunity to test and analyze catalysts for the one step oxidation of benzene to phenol and compare them with catalysts for the reduction of nitrogen oxides, using hydrocarbons as the reductant. In both projects catalysts have been used which contain Fe ions or oxo-ions in the cavities the zeolite MFI, often called ZSM-5. With Fe as the TM-element and MFI as the host zeolite we found that catalysts with high Fe content, prepared by technique (2) were optimal for the

  9. Liquid-phase alkylation of benzene with light olefins catalyzed by {beta} zeolites

    SciTech Connect

    Bellussi, G.; Pazzuconi, G.; Perego, C.

    1995-11-01

    The catalytic performance of zeolite {beta} in the liquid-phase alkylation of benzene is compared with that of other solid catalysts. Zeolite {beta} is more active and more selective than zeolite Y in the alkylation with propylene and ethylene to cumene and ethylbenzene (EB). In the alkylation with propylene the overall selectivity of {beta} is higher than that of the traditional {open_quotes}solid phosphoric acid.{close_quotes} The catalytic activity is affected by the composition and the particle size of zeolite {beta} samples. Decreasing the framework Al content, by direct synthesis or by partial substitution of Al for B, produces a decrease in both conversion and selectivity in cumene and EB synthesis. A hypothesis to explain this behavior is given. The catalytic activity of zeolite {beta} is limited by intraparticle diffusion, as evidenced by the decreased activity corresponding to the particle size increase. 22 refs., 7 figs., 10 tabs.

  10. Oxygen and hydrogen isotope geochemistry of zeolites

    NASA Technical Reports Server (NTRS)

    Karlsson, Haraldur R.; Clayton, Robert N.

    1990-01-01

    Oxygen and hydrogen isotope ratios for natural samples of the zeolites analcime, chabazite, clinoptilolite, laumontite, mordenite, and natrolite have been obtained. The zeolite samples were classified into sedimentary, hydrothermal, and igneous groups. The ratios for each species of zeolite are reported. The results are used to discuss the origin of channel water, the role of zeolites in water-rock interaction, and the possibility that a calibrated zeolite could be used as a low-temperature geothermometer.

  11. Activated carbons from North Dakota lignite and leonardite

    SciTech Connect

    Young, B.C.; Olson, E.S.; Knudson, C.L.; Timpe, R.C.

    1995-12-31

    The EERC is undertaking a research and development program on carbon development, part of which is directed towards investigating the key parameters in the preparation of activated carbons from low-rank coals indigenous to North Dakota. Carbons have been prepared and characterized for potential sorption applications in flue gas and waste liquid streams. Lignite, owing to its wide occurrence and variability in properties, has received significant attention as a precursor of active carbon manufacture. Mineral matter content and its alkaline nature are two highly variable properties that can have important consequences on the production of suitable activated carbons. Other factors affecting the production include carbonizing conditions, the activation agents, activation temperature, and activation time. However, as previously noted, the relationship between the above factors and the sorption activity is particularly complex. Part of the difficulty is that sorption activity encompasses at least three parameters, namely, surface area, pore distribution, and surface acidity/basicity. The presence of mineral matter in the coal can affect not only carbonization but also the activation and subsequent sorption and desorption processes. This paper presents results of an investigation of demineralization, carbonization temperature, activation temperature, and activation time for one lignite and leonardite from North Dakota.

  12. Phenol adsorption by activated carbon produced from spent coffee grounds.

    PubMed

    Castro, Cínthia S; Abreu, Anelise L; Silva, Carmen L T; Guerreiro, Mário C

    2011-01-01

    The present work highlights the preparation of activated carbons (ACs) using spent coffee grounds, an agricultural residue, as carbon precursor and two different activating agents: water vapor (ACW) and K(2)CO(3) (ACK). These ACs presented the microporous nature and high surface area (620-950 m(2) g(-1)). The carbons, as well as a commercial activated carbon (CAC) used as reference, were evaluated as phenol adsorbent showing high adsorption capacity (≈150 mg g(-1)). The investigation of the pH solution in the phenol adsorption was also performed. The different activating agents led to AC with distinct morphological properties, surface area and chemical composition, although similar phenol adsorption capacity was verified for both prepared carbons. The production of activated carbons from spent coffee grounds resulted in promising adsorbents for phenol removal while giving a noble destination to the residue. PMID:22105129

  13. Phonolite-hosted zeolite deposits in the Kaiserstuhl Volcanic Complex, Germany

    NASA Astrophysics Data System (ADS)

    Weisenberger, Tobias; Spürgin, Simon

    2014-05-01

    intrusions and through time. Zeolites formed during sub-solidus hydrothermal alteration under alkaline conditions and completely replace feldspathoid minerals in the matrix of the rock. A sequence of Ca-Na dominated zeolite species (gonnardite, thomsonite, mesolite) is followed by pure sodium endmember species (analcime, natrolite). These sequence reflects an increase in log[aNa+)/(aH+)] of the precipitating fluid. In contrast to the Fohberg phonolitc the Endhale phonolite contains analcime in addition to natrolite as pure Na zeolite species. The appearance of analcime is caused by higher silica activity during fluid rock interaction, which favors the formation of analcime over natrolite. The Fohberg phonolite is cut by fractures, which are totally or partially sealed with secondary minerals. Secondary minerals contain zeolites, followed by calcite and a variety of other silicates, carbonates, and sulphates as younger generations. Stable isotope analyses of late fracture calcite indicate the late circulation of meteoric fluids and mobilization of organic matter from surrounding sedimentary units.

  14. Synthesis of fluorescent carbon nanoparticles directly from active carbon via a one-step ultrasonic treatment

    SciTech Connect

    Li, Haitao; He, Xiaodie; Liu, Yang; Yu, Hang; Kang, Zhenhui; Lee, Shuit-Tong

    2011-01-15

    Water-soluble fluorescent carbon nanoparticles were synthesized directly from active carbon by a one-step hydrogen peroxide-assisted ultrasonic treatment. The carbon nanoparticles were characterized by transmission electron microscopy, optical fluorescent microscopy, fluorescent spectroscopy, Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometer. The results showed that the surface of carbon nanoparticles was rich of hydroxyl groups resulting in high hydrophilicity. The carbon nanoparticles could emit bright and colorful photoluminescence covering the entire visible-to-near infrared spectral range. Furthermore, these carbon nanoparticles also had excellent up-conversion fluorescent properties.

  15. [Effects of different fertilizer application on soil active organic carbon].

    PubMed

    Zhang, Rui; Zhang, Gui-Long; Ji, Yan-Yan; Li, Gang; Chang, Hong; Yang, Dian-Lin

    2013-01-01

    The variation characteristics of the content and components of soil active organic carbon under different fertilizer application were investigated in samples of calcareous fluvo-aquic soil from a field experiment growing winter wheat and summer maize in rotation in the North China Plain. The results showed that RF (recommended fertilization), CF (conventional fertilization) and NPK (mineral fertilizer alone) significantly increased the content of soil dissolved organic carbon and easily oxidized organic carbon by 24.92-38.63 mg x kg(-1) and 0.94-0.58 mg x kg(-1) respectively compared to CK (unfertilized control). The soil dissolved organic carbon content under OM (organic manure) increased greater than those under NPK and single fertilization, soil easily oxidized organic carbon content under OM and NPK increased greater than that under single chemical fertilization. OM and NPK showed no significant role in promoting the soil microbial biomass carbon, but combined application of OM and NPK significantly increased the soil microbial biomass carbon content by 36.06% and 20.69%, respectively. Soil easily oxidized organic carbon, dissolved organic carbon and microbial biomass carbon accounted for 8.41% - 14.83%, 0.47% - 0.70% and 0.89% - 1.20% of the total organic carbon (TOC), respectively. According to the results, the fertilizer application significantly increased the proportion of soil dissolved organic carbon and easily oxidized organic carbon, but there was no significant difference in the increasing extent of dissolved organic carbon. The RF and CF increased the proportion of soil easily oxidized organic carbon greater than OM or NPK, and significantly increased the proportion of microbial biomass carbon. OM or RF had no significant effect on the proportion of microbial biomass carbon. Therefore, in the field experiment, appropriate application of organic manure and chemical fertilizers played an important role for the increase of soil active organic carbon

  16. Properties and applications of zeolites.

    PubMed

    Rhodes, Christopher J

    2010-01-01

    Zeolites are aluminosilicate solids bearing a negatively charged honeycomb framework of micropores into which molecules may be adsorbed for environmental decontamination, and to catalyse chemical reactions. They are central to green-chemistry since the necessity for organic solvents is minimised. Proton-exchanged (H) zeolites are extensively employed in the petrochemical industry for cracking crude oil fractions into fuels and chemical feedstocks for other industrial processes. Due to their ability to perform cation-exchange, in which the cations that are originally present to counterbalance the framework negative charge may be exchanged out of the zeolite by cations present in aqueous solution, zeolites are useful as industrial water-softeners, in the removal of radioactive Cs+ and Sr2+ cations from liquid nuclear waste and in the removal of toxic heavy metal cations from groundwaters and run-off waters. Surfactant-modified zeolites (SMZ) find particular application in the co-removal of both toxic anions and organic pollutants. Toxic anions such as arsenite, arsenate, chromate, cyanide and radioactive iodide can also be removed by adsorption into zeolites that have been previously loaded with co-precipitating metal cations such as Ag+ and Pb2+ which form practically insoluble complexes that are contained within the zeolite matrix. PMID:21047018

  17. Interaction forces between waterborne bacteria and activated carbon particles.

    PubMed

    Busscher, Henk J; Dijkstra, Rene J B; Langworthy, Don E; Collias, Dimitris I; Bjorkquist, David W; Mitchell, Michael D; Van der Mei, Henny C

    2008-06-01

    Activated carbons remove waterborne bacteria from potable water systems through attractive Lifshitz-van der Waals forces despite electrostatic repulsion between negatively charged cells and carbon surfaces. In this paper we quantify the interaction forces between bacteria with negatively and positively charged, mesoporous wood-based carbons, as well as with a microporous coconut carbon. To this end, we glued carbon particles to the cantilever of an atomic force microscope and measured the interaction forces upon approach and retraction of thus made tips. Waterborne Raoultella terrigena and Escherichia coli adhered weakly (1-2 nN) to different activated carbon particles, and the main difference between the activated carbons was the percentage of curves with attractive sites revealed upon traversing of a carbon particle through the bacterial EPS layer. The percentage of curves showing adhesion forces upon retraction varied between 21% and 69%, and was highest for R. terrigena with positively charged carbon (66%) and a coconut carbon (69%). Macroscopic bacterial removal by the mesoporous carbon particles increased with increasing percentages of attractive sites revealed upon traversing a carbon particle through the outer bacterial surface layer. PMID:18405910

  18. Preparation, Processing, and Characterization of Oriented Polycrystalline Zeolite and Aluminophosphate Membranes

    NASA Astrophysics Data System (ADS)

    Stoeger, Jared Andrew

    Since the advent of zeolite membranes, speculation on their industrial applicability has been closely monitored, although widespread commercialization has been hampered by limitations in fabrication and post-synthesis processing. Economical, energy-efficient technology breakthroughs require an evaluation of a range of material candidates which show robustness and reliability. Straightforward manufacturing techniques should be devised to generate thousands of square meters of membrane area; however, this demands control of structural characteristics on the scale of nanometers. As described in this dissertation, the path forward will be forged by exploiting the intrinsic crystalline properties of zeolites or aluminophosphates for the next advancement in membrane technology. A facile method is described for the preparation of silicalite-1 (MFI zeolite type) membranes using the secondary growth technique on symmetric porous stainless steel tubes. Activation through rapid thermal processing (RTP), a lamp-based heat-treatment process used as a critical fabrication step in silicon integrated circuit manufacturing, is proven to reduce the density of non-zeolitic transport pathways which are detrimental to high-resolution molecular sieving. RTP-treated membranes are shown to have enhanced performance in the binary separation of vapor-phase isomers (p-/o-xylene), gas-phase isomers (n-/i-butane), and alcohol/water when compared to membranes activated at a much slower heating rate but otherwise similarly-prepared. The performance is discussed in the context of the market potential for industrially-attractive separations: the recovery of p-xylene from an isomeric mixture or alcohol biofuels from aqueous post-fermentation streams. Hydrothermal growth techniques for the preparation and characterization of continuous aluminophosphate (AFI zeolite type) membranes with a preferential crystallographic alignment on porous alpha-Al2O3 disc supports are demonstrated. A mechanism is

  19. Zeolite Membrane Reactor for Water Gas Shift Reaction for Hydrogen Production

    SciTech Connect

    Lin, Jerry Y.S.

    2013-01-29

    Gasification of biomass or heavy feedstock to produce hydrogen fuel gas using current technology is costly and energy-intensive. The technology includes water gas shift reaction in two or more reactor stages with inter-cooling to maximize conversion for a given catalyst volume. This project is focused on developing a membrane reactor for efficient conversion of water gas shift reaction to produce a hydrogen stream as a fuel and a carbon dioxide stream suitable for sequestration. The project was focused on synthesizing stable, hydrogen perm-selective MFI zeolite membranes for high temperature hydrogen separation; fabricating tubular MFI zeolite membrane reactor and stable water gas shift catalyst for membrane reactor applications, and identifying experimental conditions for water gas shift reaction in the zeolite membrane reactor that will produce a high purity hydrogen stream. The project has improved understanding of zeolite membrane synthesis, high temperature gas diffusion and separation mechanisms for zeolite membranes, synthesis and properties of sulfur resistant catalysts, fabrication and structure optimization of membrane supports, and fundamentals of coupling reaction with separation in zeolite membrane reactor for water gas shift reaction. Through the fundamental study, the research teams have developed MFI zeolite membranes with good perm-selectivity for hydrogen over carbon dioxide, carbon monoxide and water vapor, and high stability for operation in syngas mixture containing 500 part per million hydrogen sulfide at high temperatures around 500°C. The research teams also developed a sulfur resistant catalyst for water gas shift reaction. Modeling and experimental studies on the zeolite membrane reactor for water gas shift reaction have demonstrated the effective use of the zeolite membrane reactor for production of high purity hydrogen stream.

  20. JPL Activated Carbon Treatment System (ACTS) for sewage

    NASA Technical Reports Server (NTRS)

    1976-01-01

    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.

  1. Removal of radionuclides using zeolites

    SciTech Connect

    Reddy, R.G.; Cai, Z.

    1996-10-01

    Adsorption of uranium(VI) from aqueous solutions on natural zeolites, i.e., chabazite, clinoptilolite, erionite and mordenite, was investigated. The influence of time and pH of the solution were studied. The results showed that uranium(VI) species are strongly adsorbed on the zeolites between pH 6 to 9. The amount of uranium adsorption is strongly dependent on pH and, to some extent, on the type of zeolites. For pH {ge} 6 and at 25 C, more than 92% of uranium from solution was removed in 10 minutes. Adsorption mechanism of uranium is discussed.

  2. Synthesis of mesoporous zeolite single crystals with cheap porogens

    SciTech Connect

    Tao Haixiang; Li Changlin; Ren Jiawen; Wang Yanqin; Lu Guanzhong

    2011-07-15

    Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals have been successfully synthesized by adding soluble starch or sodium carboxymethyl cellulose (CMC) to a conventional zeolite synthesis system. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption analysis, {sup 27}Al magic angle spinning nuclear magnetic resonance ({sup 27}Al MAS NMR), temperature-programmed desorption of ammonia (NH{sub 3}-TPD) and ultraviolet-visible spectroscopy (UV-vis). The SEM images clearly show that all zeolite crystals possess the similar morphology with particle size of about 300 nm, the TEM images reveal that irregular intracrystal pores are randomly distributed in the whole crystal. {sup 27}Al MAS NMR spectra indicate that nearly all of the Al atoms are in tetrahedral co-ordination in ZSM-5, UV-vis spectra confirm that nearly all of titanium atoms are incorporated into the framework of TS-1. The catalytic activity of meso-ZSM-5 in acetalization of cyclohexanone and meso-TS-1 in hydroxylation of phenol was also studied. The synthesis method reported in this paper is cost-effective and environmental friendly, can be easily expended to prepare other hierarchical structured zeolites. - Graphical abstract: Mesoporous zeolite single crystals were synthesized by using cheap porogens as template. Highlights: > Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals were synthesized. > Soluble starch or sodium carboxymethyl cellulose (CMC) was used as porogens. > The mesoporous zeolites had connected mesopores although closed pores existed. > Higher catalytic activities were obtained.

  3. Activated Carbon Modified with Copper for Adsorption of Propanethiol

    PubMed Central

    Moreno-Piraján, Juan Carlos; Tirano, Joaquín; Salamanca, Brisa; Giraldo, Liliana

    2010-01-01

    Activated carbons were characterized texturally and chemically before and after treatment, using surface area determination in the BET model, Boehm titration, TPR, DRX and immersion calorimetry. The adsorption capacity and the kinetics of sulphur compound removal were determined by gas chromatography. It was established that the propanethiol retention capacity is dependent on the number of oxygenated groups generated on the activated carbon surface and that activated carbon modified with CuO at 0.25 M shows the highest retention of propanethiol. Additionally is proposed a mechanism of decomposition of propenothiol with carbon-copper system. PMID:20479992

  4. Catalytic conversion of alcohols having at least three carbon atoms to hydrocarbon blendstock

    DOEpatents

    Narula, Chaitanya K.; Davison, Brian H.

    2015-11-13

    A method for producing a hydrocarbon blendstock, the method comprising contacting at least one saturated acyclic alcohol having at least three and up to ten carbon atoms with a metal-loaded zeolite catalyst at a temperature of at least 100°C and up to 550°C, wherein the metal is a positively-charged metal ion, and the metal-loaded zeolite catalyst is catalytically active for converting the alcohol to the hydrocarbon blendstock, wherein the method directly produces a hydrocarbon blendstock having less than 1 vol % ethylene and at least 35 vol % of hydrocarbon compounds containing at least eight carbon atoms.

  5. Relation between chemisorption and catalytic transformation of R{sub 2}S compounds on faujasite-type zeolites

    SciTech Connect

    Ziolek, M.; Decyk, P.

    1999-08-31

    The adsorption and transformation of sulfur organic compounds on faujasite-type zeolites are considered using ethanethiol and diethyl sulfide molecules as examples. Alkali-metal-exchanged and -protonated forms of the zeolites presenting various nature and various strength of the active centers were applied. The difference in thiol and sulfide chemisorption on MNaY zeolites (M = Li, K, Rb, Cs) relies on the formation of the hydrogen bond between ethanethiol and the basic sites of zeolites together with the coordination bond which occurs for both thiol and sulfide. That implicates the high activity of MNaY zeolites in the decomposition of ethanethiol. Protonated forms of zeolites are highly active in the transformation of diethyl sulfide to ethene and ethanethiol thanks to the formation of hydrogen bonding species followed by the protonation of the sulfide molecule.

  6. Acoustical Evaluation of Carbonized and Activated Cotton Nonwovens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The process of manufacturing a carbonized and activated nonwoven made by cotton fiber was investigated in this paper. The study was focused on the acoustic application and nonwoven composites with cotton nonwoven as a base layer and glass fiber nonwoven, cotton nonwoven, and carbonized and activated...

  7. Preparation of nitrogen-enriched activated carbons from brown coal

    SciTech Connect

    Robert Pietrzak; Helena Wachowska; Piotr Nowicki

    2006-05-15

    Nitrogen-enriched activated carbons were prepared from a Polish brown coal. Nitrogen was introduced from urea at 350{sup o}C in an oxidizing atmosphere both to carbonizates obtained at 500-700{sup o}C and to activated carbons prepared from them. The activation was performed at 800{sup o}C with KOH in argon. It has been observed that the carbonization temperature determines the amount of nitrogen that is incorporated (DC5U, 8.4 wt % N{sup daf}; DC6U, 6.3 wt % N{sup daf}; and DC7U, 5.4 wt % N{sup daf}). X-ray photoelectron spectroscopy (XPS) measurements have shown that nitrogen introduced both at the stage of carbonizates and at the stage of activated carbons occurs mainly as -6, -5, and imine, amine and amide groups. On the other hand, the activation of carbons enriched with nitrogen results in the formation of pyridonic nitrogen and N-Q. The introduction of nitrogen at the activated carbon stage leads to a slight decrease in surface area. It has been proven that the most effective way of preparing microporous activated carbons enriched with nitrogen to a considerable extent and having high surface area ({approximately} 3000 m{sup 2}/g) is the following: carbonization - activation - reaction with urea. 40 refs., 1 fig., 6 tabs.

  8. Conversion of biomass to ethanol: Isomerization of xylose over HY zeolite

    SciTech Connect

    Lee, C.Y.; Wen, J.; Thomas, S.

    1995-12-31

    Xylose, a pentose indigestible to most yeasts, was converted to ethanol by a two-step isomerization and fermentation. HY zeolite was used to catalyze the isomerization of xylose, and the xylulose produced was directly used as the carbon source in ethanol fermentation. Zeolite catalysts offer pH compatibility with yeast fermentation and the ability to carry out isomerization at higher temperature where equilibrium xylulose concentration is higher. Initial rate studies indicate that xylose consumption follows pseudo-first-order kinetics, with a specific rate constant of 6.2 x 10{sup -4} L/solution/g zeolite/h.

  9. A Magnesium-Activated Carbon Hybrid Capacitor

    SciTech Connect

    Yoo, HD; Shterenberg, I; Gofer, Y; Doe, RE; Fischer, CC; Ceder, G; Aurbach, D

    2013-12-11

    Prototype cells of hybrid capacitor were developed, comprising activated carbon (AC) cloth and magnesium (Mg) foil as the positive and negative electrodes, respectively. The electrolyte solution included ether solvent (TBF) and a magnesium organo-halo-aluminate complex 0.25 M Mg2Cl3+-Ph2AlCl2-. In this solution Mg can be deposited/dissolved reversibly for thousands of cycles with high reversibility (100% cycling efficiency). The main barrier for integrating porous AC electrodes with this electrolyte solution was the saturation of the pores with the large ions in the AC prior to reaching the potential limit. This is due to the existence of bulky Mg and Al based ionic complexes consisting Cl, alkyl or aryl (R), and THF ligands. This problem was resolved by adding 0.5 M of lithium chloride (LiCl), thus introducing smaller ionic species to the solution. This Mg hybrid capacitor system demonstrated a stable cycle performance for many thousands of cycles with a specific capacitance of 90 Fg(-1) for the AC positive electrodes along a potential range of 2.4 V. (C) 2014 The Electrochemical Society. All rights reserved.

  10. Mesostructured zeolites: bridging the gap between zeolites and MCM-41.

    PubMed

    Prasomsri, Teerawit; Jiao, Wenqian; Weng, Steve Z; Garcia Martinez, Javier

    2015-05-28

    Surfactant-templating is one of the most versatile and useful techniques to implement mesoporous systems into solid materials. Various strategies based on various interactions between surfactants and solid precursors have been explored to produce new structures. Zeolites are invaluable as size- and shape-selective solid acid catalysts. Nevertheless, their micropores impose limitations on the mass transport of bulky feed and/or product molecules. Many studies have attempted to address this by utilizing surfactant-assisting technology to alleviate the diffusion constraints. However, most efforts have failed due to micro/mesopore phase separation. Recently, a new technique combining the uses of cationic surfactants and mild basic solutions was introduced to synthesise mesostructured zeolites. These materials sustain the unique characteristics of zeolites (i.e., strong acidity, crystallinity, microporosity, and hydrothermal stability), including tunable mesopore sizes and degrees of mesoporosity. The mesostructured zeolites are now commercially available through Rive Technology, and show superior performance in VGO cracking. This feature article provides an overview of recent explorations in the introduction of mesoporosity into zeolites using surfactant-templating techniques. Various porous materials, preparation methods, physical and catalytic properties of mesostructured zeolites will be discussed. PMID:25866848

  11. Ozone Removal by Filters Containing Activated Carbon: A Pilot Study

    SciTech Connect

    Fisk, William; Spears, Mike; Sullivan, Douglas; Mendell, Mark

    2009-09-01

    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.

  12. Active Marine Subsurface Bacterial Population Composition in Low Organic Carbon Environments from IODP Expedition 320

    NASA Astrophysics Data System (ADS)

    Shepard, A.; Reese, B. K.; Mills, H. J.; IODP Expedition 320 Shipboard Science Party

    2011-12-01

    The marine subsurface environment contains abundant and active microorganisms. These microbial populations are considered integral players in the marine subsurface biogeochemical system with significance in global geochemical cycles and reservoirs. However, variations in microbial community structure, activity and function associated with the wide-ranging sedimentary and geochemical environments found globally have not been fully resolved. Integrated Ocean Drilling Program Expedition 320 recovered sediments from site U1332. Two sampling depths were selected for analysis that spanned differing lithological units in the sediment core. Sediments were composed of mostly clay with zeolite minerals at 8 meters below sea floor (mbsf). At 27 mbsf, sediments were composed of alternating clayey radiolarian ooze and nannofossil ooze. The concentration of SO42- had little variability throughout the core and the concentration of Fe2+ remained close to, or below, detection limits (0.4 μM). Total organic carbon content ranged from a low of 0.03 wt% to a high of 0.07 wt% between 6 and 30 mbsf providing an opportunity to evaluate marine subsurface microbial communities under extreme electron donor limiting conditions. The metabolically active fraction of the bacterial population was isolated by the extraction and amplification of 16S ribosomal RNA. Pyrosequencing of 16S rRNA transcripts and subsequent bioinformatic analyses provided a robust data set (15,931 total classified sequences) to characterize the community at a high resolution. As observed in other subsurface environments, the overall diversity of active bacterial populations decreased with depth. The population shifted from a diverse but evenly distributed community at approximately 8 mbsf to a Firmicutes dominated population at 27 mbsf (80% of sequences). A total of 95% of the sequences at 27 mbsf were grouped into three genera: Lactobacillus (phylum Firmicutes) at 80% of the total sequences, Marinobacter (phylum

  13. [Effect of Nano Zeolite on Chemical Fractions of Cd in Soil and Its Uptake by Cabbage].

    PubMed

    Xiong, Shi-juan; Xu, Wei-hong; Xie, Wen-wen; Chen, Rong; Chen, Yong-qin; Chi, Sun-lin; Chen, Xu- gen; Zhang, Jin-zhong; Xiong, Zhi-ting; Wang, Zheng-yin; Xie, De-ti

    2015-12-01

    Incubation experiments were carried out to investigate the influence of different nano zeolite (NZ) and ordinary zeolite (OZ) levels(0, 5, 10 and 20 g · kg⁻¹) on the change trends in fraction distribution coefficient (FDC) of Cd when exposed to different Cadmium (Cd) levels (1, 5, 10 and 15 mg · kg⁻¹), and pot experiments were carried out to investigate their influence on soil Cd fraction and Cd uptake by cabbage. The results in incubation experiments showed that the application of nano zeolite as well as ordinary zeolite effectively decreased the FDC of exchangeable Cd and increased the FDC of Fe-Mn oxide fraction. The FDC of soil Cd from 0 d to 28 d was deceased at first, then increased and tended to be stable, and finally increased. At the end of incubation, the FDC of soil exchangeable Cd decreased from 72.0%-88.0% to 30.0%-66.4%. Exchangeable fraction Cd was the most dominant Cd fraction in soil during the whole incubation. The results in pot experiment indicated that the application of nano zeolite and ordinary zeolite decreased the concentration and FDC of soil exchangeable Cd, and concurrently the concentration and FDC of Cd in carbonate, Fe-Mn oxide, organic matter and residual fraction were increased. The lowest EX-Cd was observed in the treatment with high dose of nano zeolite (20 g · kg⁻¹). The FDC of exchangeable Cd showed significant negative relationship with the soil pH (P < 0.05), and was concurrently extremely positively correlated with Cd concentration in shoot and root of cabbage (P < 0.01). Soil pH increased by 1.8%-45.5% and 6.1%-54.3% in the presence of zeolite when exposed to 5 mg · kg⁻¹ 1 and Cd, respectively; FDC of exchangeable Cd decreased by 16.3%-47.7% and 16.2%-46.7%; Cd concentration in each tissues of cabbage decreased by 1.0%-75.0% and 3.8%-53.2%, respectively. Moreover, the reduction effect of nano zeolite on soil and plant Cd was better than that of ordinary zeolite. The growth of cabbage was stimulated by low and

  14. Selecting activated carbon for water and wastewater treatability studies

    SciTech Connect

    Zhang, W.; Chang, Q.G.; Liu, W.D.; Li, B.J.; Jiang, W.X.; Fu, L.J.; Ying, W.C.

    2007-10-15

    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.

  15. Effect of the formation of secondary pores in zeolite ZSM-5 on the properties of molybdenum-zeolite catalysts for methane aromatization

    NASA Astrophysics Data System (ADS)

    Kucherov, A. V.

    2014-03-01

    A study is performed of 4% Mo/ZSM-5 (30) catalysts for methane aromatization prepared by solid-phase synthesis with mechanical mixing of a zeolite with MoO3 followed by calcination at 550°C. Zeolite etched with sodium hydroxide solutions and dealuminated with aluminum nitrate solutions is used as a support. Catalytic studies of the catalysts are conducted. The effect of treating the initial zeolite on the properties of catalysts in methane aromatization is determined. The effect subsequently treating a zeolite support has on the acid sites of a catalyst is confirmed by means of temperature-programmed reduction and the temperature-programmed desorption of NH3. The formation of molybdenum ions in the +5 oxidation state during catalysis and the presence of graphitized carbon deposits on a spent catalyst's surface are confirmed by EPR and temperature-programmed oxidation.

  16. Copper-containing zeolite catalysts

    DOEpatents

    Price, Geoffrey L.; Kanazirev, Vladislav

    1996-01-01

    A catalyst useful in the conversion of nitrogen oxides or in the synthesis of nitriles or imines from amines, formed by preparing an intimate mechanical mixture of a copper (II)-containing species, such as CuO or CuCl.sub.2, or elemental copper, with a zeolite having a pore mouth comprising 10 oxygen atoms, such as ZSM-5, converting the elemental copper or copper (II) to copper (I), and driving the copper (I) into the zeolite.

  17. Copper-containing zeolite catalysts

    DOEpatents

    Price, G.L.; Kanazirev, V.

    1996-12-10

    A catalyst useful in the conversion of nitrogen oxides or in the synthesis of nitriles or imines from amines, is formed by preparing an intimate mechanical mixture of a copper (II)-containing species, such as CuO or CuCl{sub 2}, or elemental copper, with a zeolite having a pore mouth comprising 10 oxygen atoms, such as ZSM-5, converting the elemental copper or copper (II) to copper (I), and driving the copper (I) into the zeolite.

  18. Preparation and characterization of activated carbon produced from pomegranate seeds by ZnCl 2 activation

    NASA Astrophysics Data System (ADS)

    Uçar, Suat; Erdem, Murat; Tay, Turgay; Karagöz, Selhan

    2009-08-01

    In this study, pomegranate seeds, a by-product of fruit juice industry, were used as precursor for the preparation of activated carbon by chemical activation with ZnCl 2. The influence of process variables such as the carbonization temperature and the impregnation ratio on textural and chemical-surface properties of the activated carbons was studied. When using the 2.0 impregnation ratio at the carbonization temperature of 600 °C, the specific surface area of the resultant carbon is as high as 978.8 m 2 g -1. The results showed that the surface area and total pore volume of the activated carbons at the lowest impregnation ratio and the carbonization temperature were achieved as high as 709.4 m 2 g -1 and 0.329 cm 3 g -1. The surface area was strongly influenced by the impregnation ratio of activation reagent and the subsequent carbonization temperature.

  19. DIRECT DECOMPOSITION OF METHANE TO HYDROGEN ON METAL LOADED ZEOLITE CATALYST

    SciTech Connect

    Lucia M. Petkovic; Daniel M. Ginosar; Kyle C. Burch; Harry W. Rollins

    2005-08-01

    The manufacture of hydrogen from natural gas is essential for the production of ultra clean transportation fuels. Not only is hydrogen necessary to upgrade low quality crude oils to high-quality, low sulfur ultra clean transportation fuels, hydrogen could eventually replace gasoline and diesel as the ultra clean transportation fuel of the future. Currently, refinery hydrogen is produced through the steam reforming of natural gas. Although efficient, the process is responsible for a significant portion of refinery CO2 emissions. This project is examining the direct catalytic decomposition of methane as an alternative to steam reforming. The energy required to produce one mole of hydrogen is slightly lower and the process does not require water-gas-shift or pressure-swing adsorption units. The decomposition process does not produce CO2 emissions and the product is not contaminated with CO -- a poison for PEM fuel cells. In this work we examined the direct catalytic decomposition of methane over a metal modified zeolite catalyst and the recovery of catalyst activity by calcination. A favorable production of hydrogen was obtained, when compared with previously reported nickel-zeolite supported catalysts. Reaction temperature had a strong influence on catalyst activity and on the type of carbon deposits. The catalyst utilized at 873 and 973 K could be regenerated without any significant loss of activity, however the catalyst utilized at 1073 K showed some loss of activity after regeneration.

  20. Studies relevant to the catalytic activation of carbon monoxide

    SciTech Connect

    Ford, P.C.

    1992-06-04

    Research activity during the 1991--1992 funding period has been concerned with the following topics relevant to carbon monoxide activation. (1) Exploratory studies of water gas shift catalysts heterogenized on polystyrene based polymers. (2) Mechanistic investigation of the nucleophilic activation of CO in metal carbonyl clusters. (3) Application of fast reaction techniques to prepare and to investigate reactive organometallic intermediates relevant to the activation of hydrocarbons toward carbonylation and to the formation of carbon-carbon bonds via the migratory insertion of CO into metal alkyl bonds.

  1. Novel modified zeolites for energy-efficient hydrocarbon separations.

    SciTech Connect

    Arruebo, Manuel; Dong, Junhang; Anderson, Thomas (Burns and McDonnell, Kansas City, MO); Gu, Xuehong; Gray, Gary (Goodyear Chemical Company, Akron, OH); Bennett, Ron (Goodyear Chemical Company, Akron, OH); Nenoff, Tina Maria; Kartin, Mutlu; Johnson, Kaylynn (Goodyear Chemical Company, Akron, OH); Falconer, John; Noble, Richard

    2006-11-01

    We present synthesis, characterization and testing results of our applied research project, which focuses on the effects of surface and skeletal modification of zeolites for significant enhancements in current hydrocarbon (HC) separations. Zeolites are commonly used by the chemical and petroleum industries as catalysts and ion-exchangers. They have high potential for separations owing to their unique pore structures and adsorption properties and their thermal, mechanical and chemical properties. Because of zeolites separation properties, low cost, and robustness in industrial process, they are natural choice for use as industrial adsorbents. This is a multidisciplinary effort to research, design, develop, engineer, and test new and improved materials for the separation of branched vs. linear organic molecules found in commercially important HC streams via adsorption based separations. The focus of this project was the surface and framework modification of the commercially available zeolites, while tuning the adsorption properties and the selectivities of the bulk and membrane separations. In particular, we are interested with our partners at Goodyear Chemical, on how to apply the modified zeolites to feedstock isoprene purification. For the characterization and the property measurements of the new and improved materials powder X-ray diffraction (PXRD), Residual Gas Analyzer-Mass Spectroscopy (RGA-MS), Electron Microscopy (SEM/EDAX), temperature programmed desorption (TPD) and surface area techniques were utilized. In-situ carbonization of MFI zeolite membranes allowed for the maximum separation of isoprene from n-pentane, with a 4.1% enrichment of the binary stream with n-pentane. In four component streams, a modified MFI membrane had high selectivities for n-pentane and 1-3-pentadiene over isoprene but virtually no separation for the 2-methyl-2-butene/isoprene pair.

  2. Impact of Sulfur Oxides on Mercury Capture by Activated Carbon

    SciTech Connect

    Presto, A.A.; Granite, E.J.

    2007-09-15

    Recent field tests of mercury removal with activated carbon injection (ACI) have revealed that mercury capture is limited in flue gases containing high concentrations of sulfur oxides (SOx). In order to gain a more complete understanding of the impact of SOx on ACI, mercury capture was tested under varying conditions of SO2 and SO3 concentrations using a packed bed reactor and simulated flue gas (SFG). The final mercury content of the activated carbons is independent of the SO2 concentration in the SFG, but the presence of SO3 inhibits mercury capture even at the lowest concentration tested (20 ppm). The mercury removal capacity decreases as the sulfur content of the used activated carbons increases from 1 to 10%. In one extreme case, an activated carbon with 10% sulfur, prepared by H2SO4 impregnation, shows almost no mercury capacity. The results suggest that mercury and sulfur oxides are in competition for the same binding sites on the carbon surface.

  3. Cellulosic carbon fibers with branching carbon nanotubes for enhanced electrochemical activities for bioprocessing applications.

    PubMed

    Zhao, Xueyan; Lu, Xin; Tze, William Tai Yin; Kim, Jungbae; Wang, Ping

    2013-09-25

    Renewable biobased carbon fibers are promising materials for large-scale electrochemical applications including chemical processing, energy storage, and biofuel cells. Their performance is, however, often limited by low activity. Herein we report that branching carbon nanotubes can enhance the activity of carbonized cellulosic fibers, such that the oxidation potential of NAD(H) was reduced to 0.55 V from 0.9 V when applied for bioprocessing. Coordinating with enzyme catalysts, such hierarchical carbon materials effectively facilitated the biotransformation of glycerol, with the total turnover number of NAD(H) over 3500 within 5 h of reaction. PMID:24020801

  4. Hydrogen adsorption on functionalized nanoporous activated carbons.

    PubMed

    Zhao, X B; Xiao, B; Fletcher, A J; Thomas, K M

    2005-05-12

    There is considerable interest in hydrogen adsorption on carbon nanotubes and porous carbons as a method of storage for transport and related energy applications. This investigation has involved a systematic investigation of the role of functional groups and porous structure characteristics in determining the hydrogen adsorption characteristics of porous carbons. Suites of carbons were prepared with a wide range of nitrogen and oxygen contents and types of functional groups to investigate their effect on hydrogen adsorption. The porous structures of the carbons were characterized by nitrogen (77 K) and carbon dioxide (273 K) adsorption methods. Hydrogen adsorption isotherms were studied at 77 K and pressure up to 100 kPa. All the isotherms were Type I in the IUPAC classification scheme. Hydrogen isobars indicated that the adsorption of hydrogen is very temperature dependent with little or no hydrogen adsorption above 195 K. The isosteric enthalpies of adsorption at zero surface coverage were obtained using a virial equation, while the values at various surface coverages were obtained from the van't Hoff isochore. The values were in the range 3.9-5.2 kJ mol(-1) for the carbons studied. The thermodynamics of the adsorption process are discussed in relation to temperature limitations for hydrogen storage applications. The maximum amounts of hydrogen adsorbed correlated with the micropore volume obtained from extrapolation of the Dubinin-Radushkevich equation for carbon dioxide adsorption. Functional groups have a small detrimental effect on hydrogen adsorption, and this is related to decreased adsorbate-adsorbent and increased adsorbate-adsorbate interactions. PMID:16852056

  5. Role of nitrogen in pore development in activated carbon prepared by potassium carbonate activation of lignin

    NASA Astrophysics Data System (ADS)

    Tsubouchi, Naoto; Nishio, Megumi; Mochizuki, Yuuki

    2016-05-01

    The present work focuses on the role of nitrogen in the development of pores in activated carbon produced from lignin by K2CO3 activation, employing a fixed bed reactor under a high-purity He stream at temperatures of 500-900 °C. The specific surface area and pore volume obtained by activation of lignin alone are 230 m2/g and 0.13 cm3/g at 800 °C, and 540 m2/g and 0.31 cm3/g at 900 °C, respectively. Activation of a mixture of lignin and urea provides a significant increase in the surface area and volume, respectively reaching 3300-3400 m2/g and 2.0-2.3 cm3/g after holding at 800-900 °C for 1 h. Heating a lignin/urea/K2CO3 mixture leads to a significant decrease in the yield of released N-containing gases compared to the results for urea alone and a lignin/urea mixture, and most of the nitrogen in the urea is retained in the solid phase. X-ray photoelectron spectroscopy and X-ray diffraction analyses clearly show that part of the remaining nitrogen is present in heterocyclic structures (for example, pyridinic and pyrrolic nitrogen), and the rest is contained as KOCN at ≤600 °C and as KCN at ≥700 °C, such that the latter two compounds can be almost completely removed by water washing. The fate of nitrogen during heating of lignin/urea/K2CO3 and role of nitrogen in pore development in activated carbon are discussed on the basis of the results mentioned above.

  6. Reprocessing of used tires into activated carbon and other products

    SciTech Connect

    Teng, H.; Serio, M.A.; Wojtowicz, M.A.; Bassilakis, R.; Solomon, P.R.

    1995-09-01

    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.

  7. Copper removal using bio-inspired polydopamine coated natural zeolites.

    PubMed

    Yu, Yang; Shapter, Joseph G; Popelka-Filcoff, Rachel; Bennett, John W; Ellis, Amanda V

    2014-05-30

    Herein, for the first time, natural clinoptilolite-rich zeolite powders modified with a bio-inspired adhesive, polydopamine (PDA), have been systematically studied as an adsorbent for copper cations (Cu(II)) from aqueous solution. Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) revealed successful grafting of PDA onto the zeolite surface. The effects of pH (2-5.5), PDA treatment time (3-24h), contact time (0 to 24h) and initial Cu(II) ion concentrations (1 to 500mgdm(-3)) on the adsorption of Cu(II) ions were studied using atomic absorption spectroscopy (AAS) and neutron activation analysis (NAA). The adsorption behavior was fitted to a Langmuir isotherm and shown to follow a pseudo-second-order reaction model. The maximum adsorption capacities of Cu(II) were shown to be 14.93mgg(-1) for pristine natural zeolite and 28.58mgg(-1) for PDA treated zeolite powders. This impressive 91.4% increase in Cu(II) ion adsorption capacity is attributed to the chelating ability of the PDA on the zeolite surface. Furthermore studies of recyclability using NAA showed that over 50% of the adsorbed copper could be removed in mild concentrations (0.01M or 0.1M) of either acid or base. PMID:24731937

  8. Zeolite A effect on calcium homeostasis in growing goats.

    PubMed

    Schwaller, D; Wilkens, M R; Liesegang, A

    2016-04-01

    The purpose of this study was to investigate the influence of 2 different concentrations of zeolite A on calcium homeostasis. Seventeen growing goats were divided into 3 groups. Whereas the control group (5 animals) received no supplementation, 2 treatment groups were supplemented with zeolite A at either 1.2 (6 animals) or 1.6 g/kg BW (6 animals), respectively. Blood and urine samples were continually drawn and bone mineral density was measured weekly by peripheral quantitative computed tomography. After 3 wks, the animals were slaughtered and samples were taken from the rumen, duodenum, and kidneys. Plasma concentrations of phosphate ( < 0.001), magnesium ( < 0.001), and 1.25-dihydroxycholecalciferol ( < 0.01) as well as renal excretion of phosphate ( < 0.05) were significantly lower in the treatment groups compared with the control group. Although bone resorption was increased in both treatment groups ( < 0.05), no alterations in bone structure were detected. Determination of gastrointestinal absorption of calcium by Ussing chamber technique and quantification of RNA and protein expression of genes known to be involved in active calcium absorption did not reveal any stimulating effect of zeolite. Plasma calcium concentrations were not altered, probably because of the sufficient dietary calcium supply. However due to the effects of zeolite on 1,25 dihydroxycholecalciferol, bone metabolism and serum concentrations of phosphate and magenesium shown in the present study, potential negative long-termin effects on the animals should be considered whenever rations with zeolite are designed. PMID:27136016

  9. Risk assessment for the transportation of radioactive zeolite liners

    SciTech Connect

    Not Available

    1982-01-01

    The risk is estimated for the shipment of radioactive zeolite liners in support of the Zeolite Vitrification Demonstration Program currently underway at Pacific Northwest Laboratory under the sponsorship of the US Department of Energy. This program will establish the feasibility of zeolite vitrification as an effective means of immobilizing high-specific-activity wastes. In this risk assessment, it is assumed that two zeolite liners, each loaded around July 1, 1981 to 60,000 Ci, will be shipped by truck around January 1, 1982. However, to provide a measure of conservatism, each liner is assumed to initially hole 70,000 Ci, with the major radioisotopes as follow: /sup 90/Sr = 3000 Ci, /sup 134/Cs = 7000 Ci, /sup 137/Cs = 60,000 Ci. Should shipment take place with essentially no delay after initial loading (regardless of loading date), the shipment loading would be only 2.7% higher than that for the assumed six-month delay. This would negligibly affect the overall risk. As a result of this risk assessment, it is concluded that the transport of the radioactive zeolite liners from TMI to PNL by truck can be conducted at an insignificant level of risk to the public.

  10. Product Selectivity Controlled by Zeolite Crystals in Biomass Hydrogenation over a Palladium Catalyst.

    PubMed

    Wang, Chengtao; Wang, Liang; Zhang, Jian; Wang, Hong; Lewis, James P; Xiao, Feng-Shou

    2016-06-29

    This work delineates the first example for controlling product selectivity in metal-catalyzed hydrogenation of biomass by zeolite crystals. The key to this success is to combine the advantages of both Pd nanoparticles (highly active sites) and zeolite micropores (controllable diffusion of reactants and products), which was achieved from encapsulation of the Pd nanoparticles inside of silicalite-I zeolite crystals as a core-shell structure (Pd@S-1). In the hydrogenation of biomass-derived furfural, the furan selectivity over the Pd@S-1 is as high as 98.7%, outperforming the furan selectivity (5.6%) over conventional Pd nanoparticles impregnated with S-1 zeolite crystals (Pd/S-1). The extraordinary furan selectivity in the hydrogenation over the Pd@S-1 is reasonably attributed to the distinguishable mass transfer of the hydrogenated products in the zeolite micropores. PMID:27308846

  11. Dry-gel synthesis of shaped binderless zeolites composed of nanosized ZSM-5

    NASA Astrophysics Data System (ADS)

    Yue, Ming Bo; Yang, Na; Jiao, Wen Qian; Wang, Yi Meng; He, Ming-Yuan

    2013-06-01

    Shaped binderless ZSM-5 zeolites are prepared via a dry-gel conversion (DGC) technique from aluminosilicate extrudates, where the addition of seed gels not only provides crystal nuclei for rapid crystallization of zeolite but also controls the size of ZSM-5 crystal. Furthermore, the introduction of amine into the steam favors the formation of nanosized ZSM-5 zeolite. Especially, the morphology of these aluminosilicate extrudates well kept in the crystallization process. The obtained shaped zeolites are characterized by X-ray diffraction (XRD), nitrogen adsorption analysis, and scanning electron micrographs (SEM). The shaped zeolites show hierarchical structure with high mesopore volume (0.22 cm3 g-1) and demonstrate similar activity as commercial ZSM-5 samples in the transformation of i-propanol to hydrocarbons reaction.

  12. Synthetic Zeolites as Controlled-Release Delivery Systems for Anti-Inflammatory Drugs.

    PubMed

    Khodaverdi, Elham; Soleimani, Hossein Ali; Mohammadpour, Fatemeh; Hadizadeh, Farzin

    2016-06-01

    Scientists have always been trying to use artificial zeolites to make modified-release drug delivery systems in the gastrointestinal tract. An ideal carrier should have the capability to release the drug in the intestine, which is the main area of absorption. Zeolites are mineral aluminosilicate compounds with regular structure and huge porosity, which are available in natural and artificial forms. In this study, soaking, filtration and solvent evaporation methods were used to load the drugs after activation of the zeolites. Weight measurement, spectroscopy FTIR, thermogravimetry and scanning electronic microscope were used to determine drug loading on the systems. Finally, consideration of drug release was made in a simulated gastric fluid and a simulated intestinal fluid for all matrixes (zeolites containing drugs) and drugs without zeolites. Diclofenac sodium (D) and piroxicam (P) were used as the drug models, and zeolites X and Y as the carriers. Drug loading percentage showed that over 90% of drugs were loaded on zeolites. Dissolution tests in stomach pH environment showed that the control samples (drug without zeolite) released considerable amount of drugs (about 90%) within first 15 min when it was about 10-20% for the matrixes. These results are favorable as NSAIDs irritate the stomach wall and it is ideal not to release much drugs in the stomach. Furthermore, release rate of drugs from matrixes has shown slower rate in comparison with control samples in intestine pH environment. PMID:26705687

  13. Liquid-phase adsorption of organic compounds by granular activated carbon and activated carbon fibers

    SciTech Connect

    Lin, S.H.; Hsu, F.M.

    1995-06-01

    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 isotherm while the ACF adsorption could be adequately described by the Langmuir or the Freundlich isotherm. Column adsorption tests indicated that the exhausted ACFs can be effectively regenerated by static in situ thermal desorption at 150 C, but the same regeneration conditions do not do as well for the exhausted GAC.

  14. Activation of peroxymonosulfate by graphitic carbon nitride loaded on activated carbon for organic pollutants degradation.

    PubMed

    Wei, Mingyu; Gao, Long; Li, Jun; Fang, Jia; Cai, Wenxuan; Li, Xiaoxia; Xu, Aihua

    2016-10-01

    Graphitic carbon nitride supported on activated carbon (g-C3N4/AC) was prepared through an in situ thermal approach and used as a metal free catalyst for pollutants degradation in the presence of peroxymonosulfate (PMS) without light irradiation. It was found that g-C3N4 was highly dispersed on the surface of AC with the increase of surface area and the exposition of more edges and defects. The much easier oxidation of C species in g-C3N4 to CO was also observed from XPS spectra. Acid Orange 7 (AO7) and other organic pollutants could be completely degraded by the g-C3N4/AC catalyst within 20min with PMS, while g-C3N4+PMS and AC+PMS showed no significant activity for the reaction. The performance of the catalyst was significantly influenced by the amount of g-C3N4 loaded on AC; but was nearly not affected by the initial solution pH and reaction temperature. In addition, the catalysts presented good stability. A nonradical mechanism accompanied by radical generation (HO and SO4(-)) in AO7 oxidation was proposed in the system. The CO groups play a key role in the process; while the exposure of more N-(C)3 group can further increase its electron density and basicity. This study can contribute to the development of green materials for sustainable remediation of aqueous organic pollutants. PMID:27214000

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

    PubMed

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

    2014-11-01

    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 μm) volume and the increase of mesopore and macropore (0.1 μm

  16. JV Task 90 - Activated Carbon Production from North Dakota Lignite

    SciTech Connect

    Steven Benson; Charlene Crocker; Rokan Zaman; Mark Musich; Edwin Olson

    2008-03-31

    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

  17. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S

    2013-02-19

    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.

  18. Activated carbon fibers and engineered forms from renewable resources

    DOEpatents

    Baker, Frederick S.

    2010-06-01

    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.

  19. Nickel adsorption by sodium polyacrylate-grafted activated carbon.

    PubMed

    Ewecharoen, A; Thiravetyan, P; Wendel, E; Bertagnolli, H

    2009-11-15

    A novel sodium polyacrylate grafted activated carbon was produced by using gamma radiation to increase the number of functional groups on the surface. After irradiation the capacity for nickel adsorption was studied and found to have increased from 44.1 to 55.7 mg g(-1). X-ray absorption spectroscopy showed that the adsorbed nickel on activated carbon and irradiation-grafted activated carbon was coordinated with 6 oxygen atoms at 2.04-2.06 A. It is proposed that this grafting technique could be applied to other adsorbents to increase the efficiency of metal adsorption. PMID:19576692

  20. Grafting of activated carbon cloths for selective adsorption

    NASA Astrophysics Data System (ADS)

    Gineys, M.; Benoit, R.; Cohaut, N.; Béguin, F.; Delpeux-Ouldriane, S.

    2016-05-01

    Chemical functionalization of an activated carbon cloth with 3-aminophthalic acid and 4-aminobenzoic acid groups by the in situ formation of the corresponding diazonium salt in aqueous acidic solution is reported. The nature and amount of selected functions on an activated carbon surface, in particular the grafted density, were determined by potentiometric titration, elemental analysis and X-ray photoelectron spectroscopy (XPS). The nanotextural properties of the modified carbon were explored by gas adsorption. Functionalized activated carbon cloth was obtained at a discrete grafting level while preserving interesting textural properties and a large porous volume. Finally, the grafting homogeneity of the carbon surface and the nature of the chemical bonding were investigated using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) technique.

  1. Probing zeolite syntheses to determine natural occurances of zeolites

    NASA Astrophysics Data System (ADS)

    Chen, H.; Song, S.; Fang, J.

    2003-12-01

    In this study, zeolites were synthesized from different glasses to probe the occurrence of zeolites in nature. The experiments were carried out with synthetic glass systems of Na2O.Al2O3.nSiO2, CaO.Al2O3.nSiO2, xNa2O.(1-x)CaO.Al2O3.nSiO2 and xNa2O.(1-x)K2O.Al2O3.6SiO2 in alkaline solutions of NaOH, KOH, Na2CO3, NH4OH, NaOH (+) NaCl and NaOH (+) KOH at temperatures ranging from 110›J to 210›J and with autogeneous pressures in the autoclaves. Synthetic products were examined by an X-ray powder diffractometer, a scanning electron microscopy with an energy dispersive spectrometer, and an electron microprobe. The minerals synthesized included zeolites, i.e., thomsonite, gismondine, amicite, garronite, gobbinsite, analcime, phillipsite, merlinoite, chabazite and mordenite; artificial synthetic zeolites, and feldspars. Chemical analyses indicated that the composition of synthetic zeolites is profoundly influenced by the composition of the initial glasses, especially the SiO2/Al2O3 ratios and cations. On the other hand, the influence of Na+ and K+ have over the formation of zeolites in solution, other ions, such as CO32- were involved in the preventing of the formation of Ca-zeolites. Comparing the experimental results with natural occurrences suggests that thomsonite, gismondine and amicite are usually found in ultrabasic and basic rocks; garronite and gobbinsite in basic to intermediate rocks; analcime, phillipsite, and chabazite in basic to acid rocks; merlinoite in high-potassium rocks; and mordenite in acid rocks. In addition, Ca-zeolites including thomsonite, gismondine and garronite are favored in fresh water environments, and alkali zeolites including gobbinsite, phillipsite, and analcime are most abundant in saline lake and deep sea conditions.

  2. Production and characterization of activated carbons from cereal grains

    SciTech Connect

    Venkatraman, A.; Walawender, W.P.; Fan, L.T.

    1996-12-31

    The term, activated carbon, is a generic name for a family of carbonaceous materials with well-developed porosities and consequently, large adsorptive capacities. Activated carbons are increasingly being consumed worldwide for environmental applications such as separation of volatiles from bulk gases and purification of water and waste-water streams. The global annual production is estimated to be around 300 million kilograms, with a rate of increase of 7% each year. Activated carbons can be prepared from a variety of raw materials. Approximately, 60% of the activated carbons generated in the United States is produced from coal; 20%, from coconut shells; and the remaining 20% from wood and other sources of biomass. The pore structure and properties of activated carbons are influenced by the nature of the starting material and the initial physical and chemical conditioning as well as the process conditions involved in its manufacture. The porous structures of charcoals and activated carbons obtained by the carbonization of kernels have been characterized.

  3. Microstructure and surface properties of lignocellulosic-based activated carbons

    NASA Astrophysics Data System (ADS)

    González-García, P.; Centeno, T. A.; Urones-Garrote, E.; Ávila-Brande, D.; Otero-Díaz, L. C.

    2013-01-01

    Low cost activated carbons have been produced via chemical activation, by using KOH at 700 °C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet-like particles with variable length and thickness, formed by highly disordered graphene-like layers with sp2 content ≈ 95% and average mass density of 1.65 g/cm3 (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m2/g and average pore width centered in the supermicropores range (1.3-1.8 nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1 mA/cm2) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

  4. Catalytic degradation of high-density polyethylene over different zeolitic structures

    SciTech Connect

    Manos, G.; Garforth, A.; Dwyer, J.

    2000-05-01

    The catalytic degradation of high-density polyethylene to hydrocarbons was studied over different zeolites. The product range was typically between C{sub 3} and C{sub 15} hydrocarbons. Distinctive patterns of product distribution were found with different zeolitic structures. Over large-pore ultrastable Y, Y, and {beta} zeolites, alkanes were the main products with less alkenes and aromatics and only very small amounts of cycloalkanes and cycloalkenes. Medium-pore mordenite and ZSM-5 gave significantly more olefins. In the medium-pore zeolites secondary bimolecular reactions were sterically hindered, resulting in higher amounts of alkenes as primary products. The hydrocarbons formed with medium-pore zeolites were lighter than those formed with large-pore zeolites. The following order was found regarding the carbon number distribution: (lighter products) ZSM-5 < mordenite < {beta} < Y < US-Y (heavier products). A similar order was found regarding the bond saturation: (more alkenes) ZSM-5 < mordenite < {beta} < Y < US-Y (more alkanes). Dependent upon the chosen zeolite, a variety of products was obtained with high values as fuel, confirming catalytic degradation of polymers as a promising method of waste plastic recycling.

  5. [Effects of Phosphate and Zeolite on the Transformation of Cd Speciation in Soil].

    PubMed

    Wang, Xiu-li; Liang, Cheng-hua; Ma, Zi-hui; Han, Yue

    2015-04-01

    The test simulated exogenous Cd contaminated soil indoors, and studied separate application of potassium dihydrogen phosphate, diammonium hydrogen phosphate and zeolite, and combined application of zeolite and dipotassium hydrogen phosphate, zeolite and diammonium hydrogen phosphate, as well as the effect on the morphological changes of Cd contaminated soil. The results showed that soil exchangeable Cd contents were reduced in different degrees after the application of different modifiers, and the carbonate bound and Fe-Mn oxide bound, organic bound and residual Cd contents increased. By comparison, the separate application of potassium dihydrogen phosphate, diammonium hydrogen phosphate and zeolite, and the combined application of zeolite and dipotassium hydrogen phosphate, zeolite and diammonium hydrogen phosphate respectively reduced the soil available Cd contents at 25.2% -51.7%, 21.6% - 46.8%, 6.4% - 23.2%, 38.6% - 61.4%, and 34.1% - 56.4%. All treatments could increase the soil available phosphorus contents, making the soil available phosphorus contents negatively correlated with the available Cd contents significantly, with the correlation coefficient r = - 0.902 6, and the soil pH values had a negative correlation with the available Cd content during the treatments. Therefore, it could be known that the changes of soil available phosphorus contents were the major factor in reducing the availability of soil cadmium under the conditions of the application of phosphate and natural zeolite. PMID:26164924

  6. Hydrogen storage on activated carbon. Final report

    SciTech Connect

    Schwarz, J.A.

    1994-11-01

    The project studied factors that influence the ability of carbon to store hydrogen and developed techniques to enhance that ability in naturally occurring and factory-produced commercial carbon materials. During testing of enhanced materials, levels of hydrogen storage were achieved that compare well with conventional forms of energy storage, including lead-acid batteries, gasoline, and diesel fuel. Using the best materials, an electric car with a modern fuel cell to convert the hydrogen directly to electricity would have a range of over 1,000 miles. This assumes that the total allowable weight of the fuel cell and carbon/hydrogen storage system is no greater than the present weight of batteries in an existing electric vehicle. By comparison, gasoline cars generally are limited to about a 450-mile range, and battery-electric cars to 40 to 60 miles. The project also developed a new class of carbon materials, based on polymers and other organic compounds, in which the best hydrogen-storing factors discovered earlier were {open_quotes}molecularly engineered{close_quotes} into the new materials. It is believed that these new molecularly engineered materials are likely to exceed the performance of the naturally occurring and manufactured carbons seen earlier with respect to hydrogen storage.

  7. Activated carbons from North Dakota lignite and leonardite

    SciTech Connect

    Young, B.C.; Olson, E.S.; Knudson, C.L.; Timpe, R.C.

    1995-12-01

    In a research and development program on carbon development, the EERC investigated key factors in the preparation of activated carbons from low-rank coals indigenous to North Dakota. The carbons were prepared for potential sorption applications with flue gas and waste liquid streams. Testing involved as-received, physically cleaned, and demineralized samples of a lignite and a leonardite. The following variables were examined: mineral matter content (7-19 wt%), carbonization temperature (350{degrees}-550{degrees}C), activation temperature (700{degrees}-1000{degrees}C), and activation time (10-60 minutes). Activated carbon samples were characterized by sorption of gaseous sulfur dioxide and liquid iodine. For both lignite and leonardite, sorption activity increased with lower mineral content and correlated with medium carbonization temperature and relatively high activation temperature but relatively short activation time. Steam activation did not significantly enhance the char`s sorptive capacity. Physically cleaned leonardite char had SO{sub 2} sorptive capacities as high as 10.9% of the sample weight at ambient temperatures.

  8. DESIGN AND CONSTRUCTION OF A MOBILE ACTIVATED CARBON REGENERATOR SYSTEM

    EPA Science Inventory

    Activated carbon adsorption has become a standard procedure for the cleanup of contaminated water streams. To facilitate such cleanup at hazardous waste and spill sites, mobile carbon adsorption units have been constructed and are now in use. Their primary drawback is the logisti...

  9. Activated carbon testing for the 200 area effluent treatment facility

    SciTech Connect

    Wagner, R.N.

    1997-01-17

    This report documents pilot and laboratory scale testing of activated carbon for use in the 200 Area Effluent Treatment Facility peroxide decomposer columns. Recommendations are made concerning column operating conditions and hardware design, the optimum type of carbon for use in the plant, and possible further studies.

  10. ACTIVATED CARBON PROCESS FOR TREATMENT OF WASTEWATERS CONTAINING HEXAVALENT CHROMIUM

    EPA Science Inventory

    The removal of hexavalent chromium, Cr(VI), from dilute aqueous solution by an activated carbon process has been investigated. Two removal mechanisms were observed; hexavalent chromium species were removed by adsorption onto the interior carbon surface and/or through reduction to...

  11. Synthetic Zeolites and Other Microporous Oxide Molecular Sieves

    NASA Astrophysics Data System (ADS)

    Sherman, John D.

    1999-03-01

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol.

  12. Direct Dual-Template Synthesis of MWW Zeolite Monolayers.

    PubMed

    Margarit, Vicente J; Martínez-Armero, Marta E; Navarro, M Teresa; Martínez, Cristina; Corma, Avelino

    2015-11-01

    A two-dimensional zeolite with the topology of MWW sheets has been obtained by direct synthesis with a combination of two organic structure-directing agents. The resultant material consists of approximately 70% single and double layers and displays a well-structured external surface area of about 300 m(2) g(-1). The delaminated zeolite prepared by means of this single-step synthetic route has a high delamination degree, and the structural integrity of the MWW layers is well preserved. The new zeolite material displayed excellent activity, selectivity, and stability when used as a catalyst for the alkylation of benzene with propylene and found to be superior to the catalysts that are currently used for producing cumene. PMID:26381669

  13. Heterogeneous radiolysis of CO 2 in the presence of zeolites

    NASA Astrophysics Data System (ADS)

    Garibov, A. A.; Velibekova, G. Z.; Agayev, T. N.

    Radiation catalytic activity of different zeolites Ca A, Na X, Na Y, LiNa Y, Ba M in CO 2 radiolysis has been investigated. This has led to studies in the catalyst porosity, the number of adsorbed CO 2 molecules and adsorption forces on their surface on the yield of CO 2 radiolysis products. A mechanism has been suggested for the observed CO 2 radiolysis processes over different zeolites. One of the possible ways to increase CO yield in radiolytic processes of CO 2 decomposition is to use various types of catalyst. (1-3) Therefore, the development of a scientific basis for appropriate catalyst selection is becoming of particular interest. For this purpose, heterogeneous CO 2 radiolysis in the presence of high-silica zeolites has been studied in this paper.

  14. The mechanism of oligomerization of ethylene on type ZSM zeolites

    SciTech Connect

    Medin, A.S.; Borovkov, V.Y.; Kazanskii, V.B.

    1986-08-01

    The kinetics of oligomerization of ethylene on high-silica zeolites in which some of the hydroxyls were substitued by methoxyl groups were studied by spectroscopy in diffusely scattered light, and the possibility of their participation in transformations of lower olefins was demonstrated. According to the results, the oligomerization of ethylene in high-silica zeolites probably does not take place according to the classic carbonium ion, but through the formation of alkoxyl structures as intermediate products. The fact that not all of the acid OH groups are active in this reaction is apparently due to the inhomogeneity of their structural environment caused by the presence of nonequivalent silicon oxygen tetrahedrons in the structure of these zeolites.

  15. Regenerative Cu/La zeolite supported desulfurizing sorbents

    NASA Technical Reports Server (NTRS)

    Voecks, Gerald E. (Inventor); Sharma, Pramod K. (Inventor)

    1991-01-01

    Efficient, regenerable sorbents for removal of H2S from fluid hydrocarbons such as diesel fuel at moderate condition comprise a porous, high surface area aluminosilicate support, suitably a synthetic zeolite, and most preferably a zeolite having a free lattice opening of at least 6 Angstroms containing from 0.1 to 0.5 moles of copper ions, lanthanum ions or their mixtures. The sorbent removes sulfur from the hydrocarbon fuel in high efficiency and can be repetitively regenerated without loss of activity.

  16. Destructive hydroisomerization of naphtha cuts over zeolitic nickel aluminosilicate catalyst

    SciTech Connect

    Abad-zade, K.I.; Rustamov, M.I.

    1987-05-01

    The authors discuss a process developed for hydroisomerization of low-octane naphtha cuts with the aim of obtaining light isoparaffinic hydrocarbons. A zeolitic Ni-Al-Si catalyst with highly dispersed nickel was synthesized. The characteristics of the naphtha cuts used are provided. Data is given on the influence of temperature on destructive hydroisomerization of the 85-195/sup 0/C cut. It is found that the zeolitic Ni-Al-Si catalyst is adequate in activity so that the naphtha cut can be subjected to thorough destructive hydroisomerization through an ionic mechanism with little formation of C/sub 1/ and C/sub 2/ hydrocarbons.

  17. Potential of sustainable hierarchical zeolites in the valorization of α-pinene.

    PubMed

    Nuttens, Nicolas; Verboekend, Danny; Deneyer, Aron; Van Aelst, Joost; Sels, Bert F

    2015-04-13

    In the valorization of α-pinene, which is an important biomass intermediate derived from turpentine oil, hierarchical (mesoporous) zeolites represent a superior class of catalysts. Hierarchical USY, ZSM-5, and beta zeolites have been prepared, characterized, and catalytically evaluated, with the aim of combining the highest catalytic performance with the most sustainable synthetic protocol. These zeolites are prepared by alkaline treatment in aqueous solutions of NH4 OH, NaOH, diethylamine, and NaOH complemented with tetrapropylammonium bromide. The hierarchical USY zeolite is the most attractive catalyst of the tested series, and is able to combine an overall organic-free synthesis with an up to sixfold activity enhancement and comparable selectivity over the conventional USY zeolite. This superior performance relates to a threefold greater activity than that of the commercial standard, namely, H2 SO4 /TiO2 . Correlation of the obtained benefits to the amount of solid lost during the postsynthetic modifications highlights that the highest activity gains are obtained with minor leaching. Furthermore, a highly zeolitic character, as determined by bulk XRD, is beneficial, but not crucial, in the conversion of α-pinene. The alkaline treatments not only result in a higher overall activity, but also a more functional external surface area, attaining up to four times the pinene conversions per square nanometer. The efficiency of the hierarchical USY zeolite is concomitantly demonstrated in the conversion of limonene and turpentine oil, which emphasizes its industrial potential. PMID:25736719

  18. TESTING GUIDELINES FOR TECHNETIUM-99 ABSORPTION ON ACTIVATED CARBON

    SciTech Connect

    BYRNES ME

    2010-09-08

    CH2M HILL Plateau Remediation Company (CHPRC) is currently evaluating the potential use of activated carbon adsorption for removing technetium-99 from groundwater as a treatment method for the Hanford Site's 200 West Area groundwater pump-and-treat system. The current pump-and-treat system design will include an ion-exchange (IX) system for selective removal of technetium-99 from selected wells prior to subsequent treatment of the water in the central treatment system. The IX resin selected for technetium-99 removal is Purolite A530E. The resin service life is estimated to be approximately 66.85 days at the design technetium-99 loading rate, and the spent resin must be replaced because it cannot be regenerated. The resulting operating costs associated with resin replacement every 66.85 days are estimated at $0.98 million/year. Activated carbon pre-treatment is being evaluated as a potential cost-saving measure to offset the high operating costs associated with frequent IX resin replacement. This document is preceded by the Literature Survey of Technetium-99 Groundwater Pre-Treatment Option Using Granular Activated Carbon (SGW-43928), which identified and evaluated prior research related to technetium-99 adsorption on activated carbon. The survey also evaluated potential operating considerations for this treatment approach for the 200 West Area. The preliminary conclusions of the literature survey are as follows: (1) Activated carbon can be used to selectively remove technetium-99 from contaminated groundwater. (2) Technetium-99 adsorption onto activated carbon is expected to vary significantly based on carbon types and operating conditions. For the treatment approach to be viable at the Hanford Site, activated carbon must be capable of achieving a designated minimum technetium-99 uptake. (3) Certain radionuclides known to be present in 200 West Area groundwater are also likely to adsorb onto activated carbon. (4) Organic solvent contaminants of concern (COCs) will

  19. Selection and preparation of activated carbon for fuel gas storage

    DOEpatents

    Schwarz, James A.; Noh, Joong S.; Agarwal, Rajiv K.

    1990-10-02

    Increasing the surface acidity of active carbons can lead to an increase in capacity for hydrogen adsorption. Increasing the surface basicity can facilitate methane adsorption. The treatment of carbons is most effective when the carbon source material is selected to have a low ash content i.e., below about 3%, and where the ash consists predominantly of alkali metals alkali earth, with only minimal amounts of transition metals and silicon. The carbon is washed in water or acid and then oxidized, e.g. in a stream of oxygen and an inert gas at an elevated temperature.

  20. Natural gas storage with activated carbon from a bituminous coal

    USGS Publications Warehouse

    Sun, Jielun; Rood, M.J.; Rostam-Abadi, M.; Lizzio, A.A.

    1996-01-01

    Granular activated carbons ( -20 + 100 mesh; 0.149-0.84 mm) were produced by physical activation and chemical activation with KOH from an Illinois bituminous coal (IBC-106) for natural gas storage. The products were characterized by BET surface area, micropore volume, bulk density, and methane adsorption capacities. Volumetric methane adsorption capacities (Vm/Vs) of some of the granular carbons produced by physical activation are about 70 cm3/cm3 which is comparable to that of BPL, a commercial activated carbon. Vm/Vs values above 100 cm3/cm3 are obtainable by grinding the granular products to - 325 mesh (<0.044 mm). The increase in Vm/Vs is due to the increase in bulk density of the carbons. Volumetric methane adsorption capacity increases with increasing pore surface area and micropore volume when normalizing with respect to sample bulk volume. Compared with steam-activated carbons, granular carbons produced by KOH activation have higher micropore volume and higher methane adsorption capacities (g/g). Their volumetric methane adsorption capacities are lower due to their lower bulk densities. Copyright ?? 1996 Elsevier Science Ltd.

  1. Influence of starting zeolite on synthesis of RUT type zeolite by interzeolite conversion method

    NASA Astrophysics Data System (ADS)

    Itakura, Masaya; Ota, Kai; Shibata, Shohei; Inoue, Takayuki; Ide, Yusuke; Sadakane, Masahiro; Sano, Tsuneji

    2011-01-01

    In this study, hydrothermal conversions of *BEA and FAU type zeolites using various structure-directing agents were carried out. Highly crystalline and pure RUT type zeolites were obtained from both zeolites in the presence of tetramethylammonium hydroxide. There were no major differences between the characteristics of the RUT type zeolites obtained from the two starting zeolites. However, the Si/Al ratio and the crystallization rate of the RUT type zeolites were strongly dependent on both the framework structure and the Si/Al ratio of the starting zeolite. That is, the crystallization rate of the RUT type zeolite from the *BEA type zeolite did not depend on the Si/Al ratio of the starting *BEA type zeolite, whereas the crystallization rate of the RUT type zeolite from the FAU type zeolite was dependent on the Si/Al ratio of the starting FAU type zeolite. This suggests that the chemical structure and the concentration of locally ordered aluminosilicate species produced by the decomposition/dissolution of the starting zeolite can be altered by changing the framework structure of the zeolite.

  2. Catalytic pyrolysis using UZM-44 aluminosilicate zeolite

    DOEpatents

    Nicholas, Christopher P; Boldingh, Edwin P

    2014-04-29

    A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.k+T.sub.tAl.sub.1-xE.sub.xSi.sub.yO.sub.z where "n" is the mole ratio of Na to (Al+E), M represents a metal or metals from zinc, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, "m" is the mole ratio of M to (Al+E), "k" is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-44 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  3. Catalytic pyrolysis using UZM-44 aluminosilicate zeolite

    SciTech Connect

    Nicholas, Christopher P; Boldingh, Edwin P

    2013-12-17

    A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula Na.sub.nM.sub.m.sup.k+T.sub.tAl.sub.1-xE.sub.xSi.sub.yO.sub.z where "n" is the mole ratio of Na to (Al+E), M represents a metal or metals from zinc, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, "m" is the mole ratio of M to (Al+E), "k" is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-44 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  4. Sustainable Regeneration of Nanoparticle Enhanced Activated Carbon in Water

    EPA Science Inventory

    The regeneration and reuse of exhausted granular activated carbon (GAC) is an appropriate method for lowering operational and environmental costs. Advanced oxidation is a promising environmental friendly technique for GAC regeneration. The main objective of this research was to ...

  5. GRANULAR ACTIVATED CARBON ADSORPTION AND INFRARED REACTIVATION: A CASE STUDY

    EPA Science Inventory

    A study evaluated the effectiveness and cost of removing trace organic contaminants and surrogates from drinking water by granular activated carbon (GAC) adsorption. The effect of multiple reactivations of spent GAC was also evaluated. Results indicated that reactivated GAC eff...

  6. PREDICTING PREFERENTIAL ADSORPTION OF ORGANICS BY ACTIVATED CARBON

    EPA Science Inventory

    Preferential adsorption of organic compounds onto activated carbon from dilute aqueous solutions was studied to develop a comprehensive theoretical basis for predicting adsorption of multicomponent solutes. The research program investigates why some solutes are strong adsorbers, ...

  7. Mimicking high-silica zeolites: highly stable germanium- and tin-rich zeolite-type chalcogenides.

    PubMed

    Lin, Qipu; Bu, Xianhui; Mao, Chengyu; Zhao, Xiang; Sasan, Koroush; Feng, Pingyun

    2015-05-20

    High-silica zeolites, as exemplified by ZSM-5, with excellent chemical and thermal stability, have generated a revolution in industrial catalysis. In contrast, prior to this work, high-silica-zeolite-like chalcogenides based on germanium/tin remained unknown, even after decades of research. Here six crystalline high-germanium or high-tin zeolite-type sulfides and selenides with four different topologies are reported. Their unprecedented framework compositions give these materials much improved thermal and chemical stability with high surface area (Langmuir surface area of 782 m(2)/g(-1)) comparable to or better than zeolites. Among them, highly stable CPM-120-ZnGeS allows for ion exchange with diverse metal or complex cations, resulting in fine-tuning in porosity, fast ion conductivity, and photoelectric response. Being among the most porous crystalline chalcogenides, CPM-120-ZnGeS (exchanged with Cs(+) ions) also shows reversible adsorption with high capacity and affinity for CO2 (98 and 73 cm(3) g(-1) at 273 and 298 K, respectively, isosteric heat of adsorption = 40.05 kJ mol(-1)). Moreover, CPM-120-ZnGeS could also function as a robust photocatalyst for water reduction to generate H2. The overall activity of H2 production from water, in the presence of Na2S-Na2SO3 as a hole scavenger, was 200 μmol h(-1)/(0.10 g). Such catalytic activity remained undiminished under illumination by UV light for as long as measured (200 h), demonstrating excellent resistance to photocorrosion even under intense UV radiation. PMID:25950820

  8. n- and isoalkane adsorption mechanisms on zeolite MCM-22.

    PubMed

    Denayer, Joeri F M; Ocakoglu, Refik A; Thybaut, Joris; Marin, Guy; Jacobs, Pierre; Martens, Johan; Baron, G V

    2006-05-01

    Low-coverage adsorption properties (Henry constants, adsorption enthalpy, and entropy) of linear and branched alkanes (C3-C8) on zeolite MCM-22 were determined using the chromatographic technique at temperatures between 420 and 540 K. It was found that adsorption enthalpy and entropy of linear alkanes vary in a nonmonotonic way with carbon number. The adsorption behavior of alkanes was rationalized on the basis of the pore geometry. Short molecules prefer to reside in the pockets of the MCM-22 supercage, where they maximize energetic interaction with the zeolite. Longer molecules reside in the larger central part of the supercage. For carbon numbers up to six, singly branched alkanes are selectively adsorbed over their linear counterparts. This preference originates from the entropic advantage of singly branched molecules inside MCM-22 supercages, where these species have high rotational freedom because of their small length. PMID:16640405

  9. Kinetics and thermodynamics of copper ions removal from wastewater by use of zeolite.

    PubMed

    Panayotova, M I

    2001-01-01

    Natural Bulgarian zeolite was tested for its ability to remove Cu2+ from model wastewater. Influence of process variables was investigated. It was found that the optimum wastewater to zeolite ratio is 100:1 and the optimum pH value of water to be treated is 5.5 to 7.5. Zeolite with finer particles shows a higher uptake capacity. The simultaneous presence of Ca2+ and Mg2+ in concentrations similar to their concentrations in Bulgarian natural water does not significantly influence the uptake of Cu2+. Zeolite modification by treating it with NaCl, CH3COONa and NaOH increases its uptake ability. Copper ions are strongly immobilized by modified zeolite and secondary pollution of water caused by its contact with preloaded zeolite is very low (1.5-2.5% of Cu2+ preliminary immobilized have been released back into acidified water). Contacting with 2 mol dm(-3) NaCl can easily regenerate loaded zeolite; best results were obtained for zeolite modified with NaCl. Requirements of Bulgarian standards for industrial wastewater can be met by a one-stage process for an initial Cu2+ concentration of 10 mg dm(-3), and by a two stage process for an initial Cu2+ concentration of 50 mg dm(-3). Uptake of Cu2+ by zeolite from neutral wastewater has proved to be as effective as Cu2+ removal by precipitation of copper hydroxide. The process of Cu2+ uptake by natural zeolite is best described by the kinetic equation for adsorption. This fact, together with the correlation found between the Cu2+ uptake and the amount of Na+, Ca2+ and K+ released into solution by zeolite shows that the ion exchange sorption plays the basic role in Cu2+ uptake by natural zeolite. The value obtained for the apparent activation energy (26.112 kJ mol(-1) implies that the process can be easily carried out with a satisfactory rate. The uptake equilibrium is best described by the Langmuir adsorption isotherm, with Langmuir constants KL= 6.4 x 10(-2) dm3 mg(-1) and M = 6.74 mg g(-1). The apparent equilibrium constant

  10. Structural analysis of hierarchically organized zeolites

    NASA Astrophysics Data System (ADS)

    Mitchell, Sharon; Pinar, Ana B.; Kenvin, Jeffrey; Crivelli, Paolo; Kärger, Jörg; Pérez-Ramírez, Javier

    2015-10-01

    Advances in materials synthesis bring about many opportunities for technological applications, but are often accompanied by unprecedented complexity. This is clearly illustrated by the case of hierarchically organized zeolite catalysts, a class of crystalline microporous solids that has been revolutionized by the engineering of multilevel pore architectures, which combine unique chemical functionality with efficient molecular transport. Three key attributes, the crystal, the pore and the active site structure, can be expected to dominate the design process. This review examines the adequacy of the palette of techniques applied to characterize these distinguishing features and their catalytic impact.

  11. Structural analysis of hierarchically organized zeolites.

    PubMed

    Mitchell, Sharon; Pinar, Ana B; Kenvin, Jeffrey; Crivelli, Paolo; Kärger, Jörg; Pérez-Ramírez, Javier

    2015-01-01

    Advances in materials synthesis bring about many opportunities for technological applications, but are often accompanied by unprecedented complexity. This is clearly illustrated by the case of hierarchically organized zeolite catalysts, a class of crystalline microporous solids that has been revolutionized by the engineering of multilevel pore architectures, which combine unique chemical functionality with efficient molecular transport. Three key attributes, the crystal, the pore and the active site structure, can be expected to dominate the design process. This review examines the adequacy of the palette of techniques applied to characterize these distinguishing features and their catalytic impact. PMID:26482337

  12. Structural analysis of hierarchically organized zeolites

    PubMed Central

    Mitchell, Sharon; Pinar, Ana B.; Kenvin, Jeffrey; Crivelli, Paolo; Kärger, Jörg; Pérez-Ramírez, Javier

    2015-01-01

    Advances in materials synthesis bring about many opportunities for technological applications, but are often accompanied by unprecedented complexity. This is clearly illustrated by the case of hierarchically organized zeolite catalysts, a class of crystalline microporous solids that has been revolutionized by the engineering of multilevel pore architectures, which combine unique chemical functionality with efficient molecular transport. Three key attributes, the crystal, the pore and the active site structure, can be expected to dominate the design process. This review examines the adequacy of the palette of techniques applied to characterize these distinguishing features and their catalytic impact. PMID:26482337

  13. Preparation and characterization of activated carbon from sugarcane bagasse by physical activation with CO2 gas

    NASA Astrophysics Data System (ADS)

    Bachrun, Sutrisno; AyuRizka, Noni; Annisa, SolichaHidayat; Arif, Hidayat

    2016-01-01

    A series of experiments have been conducted to study the effects of different carbonization temperatures (400, 600, and 800oC) on characteristics of porosity in activated carbon derived from carbonized sugarcane bagassechar at activation temperature of 800oC. The results showed that the activated carbon derived from high carbonized temperature of sugarcane bagassechars had higher BET surface area, total volume, micropore volume and yield as compared to the activated carbon derived from low carbonized temperature. The BET surface area, total volume and micropore volume of activated carbon prepared from sugarcane bagassechars obtained at 800oC of carbonized temperature and activation time of 120 min were 661.46m2/g, 0.2455cm3/g and 0.1989cm3/g, respectively. The high carbonization temperature (800oC) generated a highly microporous carbonwith a Type-I nitrogen adsorption isotherm, while the low carbonization temperature (400 and 600oC) generated a mesoporous one with an intermediate between types I and IInitrogen adsorption isotherm.

  14. Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity

    SciTech Connect

    Heben, M.; Dillon, A. C.; Engtrakul, C.; Lee, S.-H.; Kelley, R. D.; Kini, A. M.

    2007-05-01

    Carbon SWNTs are attractive materials for supporting electrocatalysts. The properties of SWNTs are highly tunable and controlled by the nanotube's circumferential periodicity and their surface chemistry. These unique characteristics suggest that architectures constructed from these types of carbon support materials would exhibit interesting and useful properties. Here, we expect that the structure of the carbon nanotube support will play a major role in stabilizing metal electrocatalysts under extreme operating conditions and suppress both catalyst and support degradation. Furthermore, the chemical modification of the carbon nanotube surfaces can be expected to alter the interface between the catalyst and support, thus, enhancing the activity and utilization of the electrocatalysts. We plan to incorporate discrete reaction sites into the carbon nanotube lattice to create intimate electrical contacts with the catalyst particles to increase the metal catalyst activity and utilization. The work involves materials synthesis, design of electrode architectures on the nanoscale, control of the electronic, ionic, and mass fluxes, and use of advanced optical spectroscopy techniques.

  15. The influence of zeolitic water on the rate of butadiene dimerization

    SciTech Connect

    1995-02-01

    Zeolites find widespread usage as catalysts for a variety of chemical transformations. Frequently, the catalytically active agent is a transition metal ion located at an exchange site in contact with the zeolitic surface. Although the extraframework cation positions and relative populations can often be determined by spectroscopic methods, the influence of cation sitting and adsorbed reactant induced migration under reaction conditions is less well understood. This note describes the role which water exerts on the activity of copper-exchanged zeolite Y for the dimerization of butadiene to 4-vinylcyclohexene (4-VCH). 12 refs., 1 fig., 1 tab.

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

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

    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.

  17. Water vapor adsorption on activated carbon preadsorbed with naphtalene.

    PubMed

    Zimny, T; Finqueneisel, G; Cossarutto, L; Weber, J V

    2005-05-01

    The adsorption of water vapor on a microporous activated carbon derived from the carbonization of coconut shell has been studied. Preadsorption of naphthalene was used as a tool to determine the location and the influence of the primary adsorbing centers within the porous structure of active carbon. The adsorption was studied in the pressure range p/p0=0-0.95 in a static water vapor system, allowing the investigation of both kinetic and equilibrium experimental data. Modeling of the isotherms using the modified equation of Do and Do was applied to determine the effect of preadsorption on the mechanism of adsorption. PMID:15797395

  18. Activated carbon fiber composite material and method of making

    DOEpatents

    Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

    2001-01-01

    An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

  19. Activated carbon fiber composite material and method of making

    DOEpatents

    Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

    2000-01-01

    An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

  20. Analysis of the biological and chemical reactivity of zeolite-based aluminosilicate fibers and particulates.

    PubMed Central

    Fach, Estelle; Waldman, W James; Williams, Marshall; Long, John; Meister, Richard K; Dutta, Prabir K

    2002-01-01

    Environmental and/or occupational exposure to minerals, metals, and fibers can cause lung diseases that may develop years after exposure to the agents. The presence of toxic fibers such as asbestos in the environment plus the continuing development of new mineral or vitreous fibers requires a better understanding of the specific physical and chemical features of fibers/particles responsible for bioactivity. Toward that goal, we have tested aluminosilicate zeolites to establish biological and chemical structure-function correlations. Zeolites have known crystal structure, are subject to experimental manipulation, and can be synthesized and controlled to produce particles of selected size and shape. Naturally occurring zeolites include forms whose biological activity is reported to range from highly pathogenic (erionite) to essentially benign (mordenite). Thus, we used naturally occurring erionite and mordenite as well as an extensively studied synthetic zeolite based on faujasite (zeolite Y). Bioactivity was evaluated using lung macrophages of rat origin (cell line NR8383). Our objective was to quantitatively determine the biological response upon interaction of the test particulates/fibers with lung macrophages and to evaluate the efficacy of surface iron on the zeolites to promote the Fenton reaction. The biological assessment included measurement of the reactive oxygen species by flow cytometry and chemiluminescence techniques upon phagocytosis of the minerals. The chemical assessment included measuring the hydroxyl radicals generated from hydrogen peroxide by iron bound to the zeolite particles and fibers (Fenton reaction). Chromatography as well as absorption spectroscopy were used to quantitate the hydroxyl radicals. We found that upon exposure to the same mass of a specific type of particulate, the oxidative burst increased with decreasing particle size, but remained relatively independent of zeolite composition. On the other hand, the Fenton reaction

  1. Carbon-carbon bond cleavage in activation of the prodrug nabumetone.

    PubMed

    Varfaj, Fatbardha; Zulkifli, Siti N A; Park, Hyoung-Goo; Challinor, Victoria L; De Voss, James J; Ortiz de Montellano, Paul R

    2014-05-01

    Carbon-carbon bond cleavage reactions are catalyzed by, among others, lanosterol 14-demethylase (CYP51), cholesterol side-chain cleavage enzyme (CYP11), sterol 17β-lyase (CYP17), and aromatase (CYP19). Because of the high substrate specificities of these enzymes and the complex nature of their substrates, these reactions have been difficult to characterize. A CYP1A2-catalyzed carbon-carbon bond cleavage reaction is required for conversion of the prodrug nabumetone to its active form, 6-methoxy-2-naphthylacetic acid (6-MNA). Despite worldwide use of nabumetone as an anti-inflammatory agent, the mechanism of its carbon-carbon bond cleavage reaction remains obscure. With the help of authentic synthetic standards, we report here that the reaction involves 3-hydroxylation, carbon-carbon cleavage to the aldehyde, and oxidation of the aldehyde to the acid, all catalyzed by CYP1A2 or, less effectively, by other P450 enzymes. The data indicate that the carbon-carbon bond cleavage is mediated by the ferric peroxo anion rather than the ferryl species in the P450 catalytic cycle. CYP1A2 also catalyzes O-demethylation and alcohol to ketone transformations of nabumetone and its analogs. PMID:24584631

  2. Carbon-Carbon Bond Cleavage in Activation of the Prodrug Nabumetone

    PubMed Central

    Varfaj, Fatbardha; Zulkifli, Siti N. A.; Park, Hyoung-Goo; Challinor, Victoria L.; De Voss, James J.

    2014-01-01

    Carbon-carbon bond cleavage reactions are catalyzed by, among others, lanosterol 14-demethylase (CYP51), cholesterol side-chain cleavage enzyme (CYP11), sterol 17β-lyase (CYP17), and aromatase (CYP19). Because of the high substrate specificities of these enzymes and the complex nature of their substrates, these reactions have been difficult to characterize. A CYP1A2-catalyzed carbon-carbon bond cleavage reaction is required for conversion of the prodrug nabumetone to its active form, 6-methoxy-2-naphthylacetic acid (6-MNA). Despite worldwide use of nabumetone as an anti-inflammatory agent, the mechanism of its carbon-carbon bond cleavage reaction remains obscure. With the help of authentic synthetic standards, we report here that the reaction involves 3-hydroxylation, carbon-carbon cleavage to the aldehyde, and oxidation of the aldehyde to the acid, all catalyzed by CYP1A2 or, less effectively, by other P450 enzymes. The data indicate that the carbon-carbon bond cleavage is mediated by the ferric peroxo anion rather than the ferryl species in the P450 catalytic cycle. CYP1A2 also catalyzes O-demethylation and alcohol to ketone transformations of nabumetone and its analogs. PMID:24584631

  3. Platinum particle size and support effects in NO(x) mediated carbon oxidation over platinum catalysts.

    PubMed

    Villani, Kenneth; Vermandel, Walter; Smets, Koen; Liang, Duoduo; van Tendeloo, Gustaaf; Martens, Johan A

    2006-04-15

    Platinum metal was dispersed on microporous, mesoporous, and nonporous support materials including the zeolites Na-Y, Ba-Y, Ferrierite, ZSM-22, ETS-10, and AIPO-11, alumina, and titania. The oxidation of carbon black loosely mixed with catalyst powder was monitored gravimetrically in a gas stream containing nitric oxide, oxygen, and water. The carbon oxidation activity of the catalysts was found to be uniquely related to the Pt dispersion and little influenced by support type. The optimum dispersion is around 3-4% corresponding to relatively large Pt particle sizes of 20-40 nm. The carbon oxidation activity reflects the NO oxidation activity of the platinum catalyst, which reaches an optimum in the 20-40 nm Pt particle size range. The lowest carbon oxidation temperatures were achieved with platinum loaded ZSM-22 and AIPO-11 zeolite crystallites bearing platinum of optimum dispersion on their external surfaces. PMID:16683615

  4. Zeolite synthesis: an energetic perspective.

    PubMed

    Zwijnenburg, Martijn A; Bromley, Stefan T

    2010-11-21

    Taking |D(H(2)O)(x)|[AlSiO(4)] based materials (where D is Li, Na, K, Rb or Cs) as an archetypal aluminosilicate system, we use accurate density functional theory calculations to demonstrate how the substitution of silicon cations in silica, with pairs of aluminium and (alkali metal) cations, changes the energetic ordering of different competing structure-types. For large alkali metal cations we further show that the formation of porous aluminosilicate structures, the so-called zeolites, is energetically favored. These findings unequivocally demonstrate that zeolites can be energetic preferred reaction products, rather than being kinetically determined, and that the size of the (hydrated) cations in the pore, be it inorganic or organic, is critical for directing zeolite synthesis. PMID:20938518

  5. A Fungal-Prokaryotic Consortium at the Basalt-Zeolite Interface in Subseafloor Igneous Crust

    PubMed Central

    Ivarsson, Magnus; Bengtson, Stefan; Skogby, Henrik; Lazor, Peter; Broman, Curt; Belivanova, Veneta; Marone, Federica

    2015-01-01

    We have after half a century of coordinated scientific drilling gained insight into Earth´s largest microbial habitat, the subseafloor igneous crust, but still lack substantial understanding regarding its abundance, diversity and ecology. Here we describe a fossilized microbial consortium of prokaryotes and fungi at the basalt-zeolite interface of fractured subseafloor basalts from a depth of 240 m below seafloor (mbsf). The microbial consortium and its relationship with the surrounding physical environment are revealed by synchrotron-based X-ray tomographic microscopy (SRXTM), environmental scanning electron microscopy (ESEM), and Raman spectroscopy. The base of the consortium is represented by microstromatolites—remains of bacterial communities that oxidized reduced iron directly from the basalt. The microstromatolites and the surrounding basalt were overlaid by fungal cells and hyphae. The consortium was overgrown by hydrothermally formed zeolites but remained alive and active during this event. After its formation, fungal hyphae bored in the zeolite, producing millimetre-long tunnels through the mineral substrate. The dissolution could either serve to extract metals like Ca, Na and K essential for fungal growth and metabolism, or be a response to environmental stress owing to the mineral overgrowth. Our results show how microbial life may be maintained in a nutrient-poor and extreme environment by close ecological interplay and reveal an effective strategy for nutrient extraction from minerals. The prokaryotic portion of the consortium served as a carbon source for the eukaryotic portion. Such an approach may be a prerequisite for prokaryotic-eukaryotic colonisation of, and persistence in, subseafloor igneous crust. PMID:26488482

  6. A Fungal-Prokaryotic Consortium at the Basalt-Zeolite Interface in Subseafloor Igneous Crust.

    PubMed

    Ivarsson, Magnus; Bengtson, Stefan; Skogby, Henrik; Lazor, Peter; Broman, Curt; Belivanova, Veneta; Marone, Federica

    2015-01-01

    We have after half a century of coordinated scientific drilling gained insight into Earth´s largest microbial habitat, the subseafloor igneous crust, but still lack substantial understanding regarding its abundance, diversity and ecology. Here we describe a fossilized microbial consortium of prokaryotes and fungi at the basalt-zeolite interface of fractured subseafloor basalts from a depth of 240 m below seafloor (mbsf). The microbial consortium and its relationship with the surrounding physical environment are revealed by synchrotron-based X-ray tomographic microscopy (SRXTM), environmental scanning electron microscopy (ESEM), and Raman spectroscopy. The base of the consortium is represented by microstromatolites-remains of bacterial communities that oxidized reduced iron directly from the basalt. The microstromatolites and the surrounding basalt were overlaid by fungal cells and hyphae. The consortium was overgrown by hydrothermally formed zeolites but remained alive and active during this event. After its formation, fungal hyphae bored in the zeolite, producing millimetre-long tunnels through the mineral substrate. The dissolution could either serve to extract metals like Ca, Na and K essential for fungal growth and metabolism, or be a response to environmental stress owing to the mineral overgrowth. Our results show how microbial life may be maintained in a nutrient-poor and extreme environment by close ecological interplay and reveal an effective strategy for nutrient extraction from minerals. The prokaryotic portion of the consortium served as a carbon source for the eukaryotic portion. Such an approach may be a prerequisite for prokaryotic-eukaryotic colonisation of, and persistence in, subseafloor igneous crust. PMID:26488482

  7. Isobutane/2-butene alkylation on ultrastable Y zeolites: Influence of zeolite unit cell size

    SciTech Connect

    Corma, A.; Martinez, A.; Martinez, C. )

    1994-03-01

    The alkylation reaction of isobutane with trans-2-butene has been carried out on a series of steam-dealuminated Y zeolites with unit cell sizes ranging from 2.450 to 2.426 nm. A fixed-bed reactor connected to an automatized multiloop sampling system allowed differential product analysis from very short (1 min or less) to longer times on stream. A maximum in the initial 2-butene conversion was found on samples with unit cell sizes between 2.435 and 2.450 nm. However, the TMP/DMH ratio, i.e., the alkylation-to-oligomerization ratio, continuously increased with zeolite unit cell size. The concentration of reactants in the pores, the strength distribution of Bronsted acid sites, and the extent of hydrogen transfer reactions, which in turn depend on the framework Si/Al ratio of a given zeolite, were seen to affect activity and product distribution of the catalysts. Finally, the influence of these factors on the aging characteristics of the samples was also discussed. 17 refs., 7 figs., 4 tabs.

  8. Wet oxidative regeneration of activated carbon loaded with reactive dye.

    PubMed

    Shende, R V; Mahajani, V V

    2002-01-01

    Wet Oxidative Regeneration (WOR) of powdered activated carbon (PAC) and granular activated carbon (GAC) loaded with the reactive dyes, namely chemictive brilliant blue R and cibacron turquoise blue G, was studied. Attempts were made to regenerate the loaded carbons designated now as spent carbon. A slurry (10% w/v) of spent carbon in distilled water was oxidized by wet oxidation in the temperature range of 150-250 degrees C using oxygen partial pressures between 0.69-1.38 MPa in an 1 1 SS 316 autoclave. The percent regeneration was determined from a ratio, X(RC)/X(VC), corresponding to an equilibrium adsorption capacity of regenerated carbon/equilibrium adsorption capacity of virgin carbon from an initial adsorption period of 3 h. It was observed that the regeneration mainly occurred due to the oxidation of the adsorbates taking place on the surface of carbon. It was possible to regenerate the spent GAC and PAC to the extent of more than 98% (approximately X(RC)/X(VC) > 0.98) by wet oxidation. After four consecutive cycles of adsorption and regeneration using the same stocks of GAC, carbon weight loss observed at 200 degrees C was about 40%. SEM studies of the regenerated carbon showed widening of the pores and loss of structure between the adjacent pores as compared with the virgin carbon. PAC was found to be more suitable as compared with GAC for the adsorption and wet oxidative regeneration processes to treat the aqueous solution containing lower concentration of unhydrolyzed reactive dye. The suitability of wet oxidative regeneration is demonstrated at a bench scale to treat the synthetic reactive dye solution. PMID:11942707

  9. Detecting Extracellular Carbonic Anhydrase Activity Using Membrane Inlet Mass Spectrometry

    PubMed Central

    Delacruz, Joannalyn; Mikulski, Rose; Tu, Chingkuang; Li, Ying; Wang, Hai; Shiverick, Kathleen T.; Frost, Susan C.; Horenstein, Nicole A.; Silverman, David N.

    2010-01-01

    Current research into the function of carbonic anhydrases in cell physiology emphasizes the role of membrane-bound carbonic anhydrases, such as carbonic anhydrase IX that has been identified in malignant tumors and is associated with extracellular acidification as a response to hypoxia. We present here a mass spectrometric method to determine the extent to which total carbonic anhydrase activity is due to extracellular carbonic anhydrase in whole cell preparations. The method is based on the biphasic rate of depletion of 18O from CO2 measured by membrane inlet mass spectrometry. The slopes of the biphasic depletion are a sensitive measure of the presence of carbonic anhydrase outside and inside of the cells. This property is demonstrated here using suspensions of human red cells in which external carbonic anhydrase was added to the suspending solution. It is also applied to breast and prostate cancer cells which both express exofacial carbonic anhydrase IX. Inhibition of external carbonic anhydrase is achieved by use of a membrane impermeant inhibitor that was synthesized for this purpose, p-aminomethylbenzenesulfonamide attached to a polyethyleneglycol polymer. PMID:20417171

  10. Adsorption of dissolved natural organic matter by modified activated carbons.

    PubMed

    Cheng, Wei; Dastgheib, Seyed A; Karanfil, Tanju

    2005-06-01

    Adsorption of dissolved natural organic matter (DOM) by virgin and modified granular activated carbons (GACs) was studied. DOM samples were obtained from two water treatment plants before (i.e., raw water) and after coagulation/flocculation/sedimentation processes (i.e., treated water). A granular activated carbon (GAC) was modified by high temperature helium or ammonia treatment, or iron impregnation followed by high temperature ammonia treatment. Two activated carbon fibers (ACFs) were also used, with no modification, to examine the effect of carbon porosity on DOM adsorption. Size exclusion chromatography (SEC) and specific ultraviolet absorbance (SUVA(254)) were employed to characterize the DOMs before and after adsorption. Iron-impregnated (HDFe) and ammonia-treated (HDN) activated carbons showed significantly higher DOM uptakes than the virgin GAC. The enhanced DOM uptake by HDFe was due to the presence of iron species on the carbon surface. The higher uptake of HDN was attributed to the enlarged carbon pores and basic surface created during ammonia treatment. The SEC and SUVA(254) results showed no specific selectivity in the removal of different DOM components as a result of carbon modification. The removal of DOM from both raw and treated waters was negligible by ACF10, having 96% of its surface area in pores smaller than 1 nm. Small molecular weight (MW) DOM components were preferentially removed by ACF20H, having 33% of its surface area in 1--3 nm pores. DOM components with MWs larger than 1600, 2000, and 2700 Da of Charleston raw, Charleston-treated, and Spartanburg-treated waters, respectively, were excluded from the pores of ACF20H. In contrast to carbon fibers, DOM components from entire MW range were removed from waters by virgin and modified GACs. PMID:15927230

  11. Gas-phase adsorption in dealuminated natural clinoptilolite and liquid-phase adsorption in commercial DAY zeolite and modified ammonium Y zeolite

    NASA Astrophysics Data System (ADS)

    Costa Hernandez, Alba Nydia

    The adsorption of Carbon Dioxide (CO2) is a very important tool for the material characterization. On the other hand, in separation and recovery technology, the adsorption of the CO2 is important to reduce the concentration of this gas considered as one of the greenhouse gases. Natural zeolites, particularly clinoptilolite, are widely applied to eliminate some pollutants from the environment. One of the goals of this research is to study the structure, composition and morphology of one natural clinoptilolite dealuminated with ammonium hexafluorosilicate (AHFi) and with orthophosphoric acid (H3PO4). Each modified sample was characterized using X-ray Diffraction (XRD), Carbon Dioxide adsorption at 0° C, Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDAX). In addition, the surface chemistry of the modified clinoptilolites was analyzed with Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS). The adsorption measurements were also used to study of the interaction of CO2 molecule within the adsorption space of these modified clinoptilolites. It was concluded that one of the modified clinoptilolites, (CSW-HFSi-0.1M), showed a great quality as adsorbent and as catalytic comparable to commercial synthetic zeolites. As far as we know, the modification of clinoptilolite with HFSi to improve their adsorption properties had not been previously attempted. In the second part of this dissertation, the dynamic adsorption of three isomers of nitrophenols using as adsorbent a commercial DAY zeolite was investigated. Also, the dynamic adsorption of methanol in a less hydrophobic zeolite, Ammonium Y Zeolite was investigated. The obtained breakthrough curves showed that the commercial DAY zeolite could be a suitable adsorbent to the liquid-phase adsorption of the phenolic compounds. Notwithstanding the modified ammonium Y zeolite had a low Si/Al ratio (less hydrophobic) than commercial DAY zeolite; this

  12. Hydrothermal synthesis and characterization of aluminum-free Mn-β zeolite: a catalyst for phenol hydroxylation.

    PubMed

    He, Zhen; Wu, Juan; Gao, Bingying; He, Hongyun

    2015-02-01

    Zeolite beta, especially heteroatomic zeolite beta, has been widely used in the industries of fine chemicals and petroleum refining because of its outstanding thermal stability, acid resistance, and unique 3-D open-frame structure. In this paper, aluminum-free Mn-β zeolite was hydrothermally synthesized in the SiO2-MnO2-(TEA)2O-NaF-H2O system. The effect of the chemical composition of the precursor mixture to the crystallization of the Al-free Mn-β zeolite was investigated. The synthesized Al-free Mn-β zeolite was characterized by inductively coupled plasma (ICP), XRD, thermogravimetric/differential thermal analysis (TG/DTA), N2 adsorption-desorption, FT-IR, UV-vis, X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The results show that the synthesized zeolite has a structure of β zeolite with good crystallinity and Mn ions present in the framework of the zeolite. The synthesized Al-free Mn-β zeolite shows great catalytic activity toward the phenol hydroxylation reaction using H2O2 as the oxidant. Approximately 35% of phenol conversion and ∼98% of dihydroxybenzene selectivity can be obtained under the optimal conditions. PMID:25556927

  13. Preparation of activated carbons from bituminous coals with zinc chloride activation

    SciTech Connect

    Teng, H.; Yeh, T.S.

    1998-01-01

    Activated carbons were prepared by chemical activation from two Australian bituminous coals in this study. The preparation process consisted of zinc chloride impregnation followed by carbonization in nitrogen. The carbonization temperature ranges from 400 to 700 C. Experimental results reveal that an acid-washing process following the carbonization with ZnCl{sub 2} is necessary for preparing high-porosity carbons. Surface area, pore volume, and average pore diameter of the resulting carbons increase with the carbonization temperature to a maximum at 500 C and then begin to decrease. The maximum values of surface area and pore volume are larger for the carbon prepared from the coal with a lower O/C atomic ratio, while earlier findings from physical activation with CO{sub 2} have shown an opposite trend. An increase in particle size of the coal precursor leads to a reduction in porosity of the resulting carbons. The duration of the carbonization period affects the porosity of the resulting carbons, and the influence varies with the activation temperature.

  14. Composite electrodes of activated carbon derived from cassava peel and carbon nanotubes for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Taer, E.; Iwantono, Yulita, M.; Taslim, R.; Subagio, A.; Salomo, Deraman, M.

    2013-09-01

    In this paper, a composite electrode was prepared from a mixture of activated carbon derived from precarbonization of cassava peel (CP) and carbon nanotubes (CNTs). The activated carbon was produced by pyrolysis process using ZnCl2 as an activation agent. A N2 adsorption-desorption analysis for the sample indicated that the BET surface area of the activated carbon was 1336 m2 g-1. Difference percentage of CNTs of 0, 5, 10, 15 and 20% with 5% of PVDF binder were added into CP based activated carbon in order to fabricate the composite electrodes. The morphology and structure of the composite electrodes were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The SEM image observed that the distribution of CNTs was homogeneous between carbon particles and the XRD pattern shown the amorphous structure of the sample. The electrodes were fabricated for supercapacitor cells with 316L stainless steel as current collector and 1 M sulfuric acid as electrolyte. An electrochemical characterization was performed by using an electrochemical impedance spectroscopy (EIS) method using a Solatron 1286 instrument and the addition of CNTs revealed to improve the resistant and capacitive properties of supercapacitor cell.

  15. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons

    NASA Astrophysics Data System (ADS)

    Brooks, A. J.; Lim, Hyung-nam; Kilduff, James E.

    2012-07-01

    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 π-electron energy to investigate the role of π-π 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

  16. Adsorption uptake of synthetic organic chemicals by carbon nanotubes and activated carbons.

    PubMed

    Brooks, A J; Lim, Hyung-nam; Kilduff, James E

    2012-07-27

    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 π-electron energy to investigate the role of π-π 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

  17. Survival of selected bacterial species in sterilized activated carbon filters and biological activated carbon filters.

    PubMed Central

    Rollinger, Y; Dott, W

    1987-01-01

    The survival of selected hygienically relevant bacterial species in activated carbon (AC) filters on a bench scale was investigated. The results revealed that after inoculation of the test strains the previously sterilized AC absorbed all bacteria (10(6) to 10(7)). After a period of 6 to 13 days without countable bacteria in the effluent, the numbers of Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas putida increased up to 10(4) to 10(5) CFU/ml of effluent and 10(6) to 10(7) CFU/g of AC. When Klebsiella pneumoniae and Streptococcus faecalis were used, no growth in filters could be observed. The numbers of E. coli, P. aeruginosa, and P. putida, however, decreased immediately and showed no regrowth in nonsterile AC from a filter which had been continuously connected to running tap water for 2 months. Under these conditions an autochthonous microflora developed on the carbon surface which could be demonstrated by scanning electron microscopy and culturing methods (heterotrophic plate count). These bacteria reduced E. coli, P. aeruginosa, and P. putida densities in the effluent by a factor of more than 10(5) within 1 to 5 days. The hypothesis that antagonistic substances of the autochthonous microflora were responsible for the elimination of the artificial contamination could not be confirmed because less than 1% of the isolates of the autochthonous microflora were able to produce such substances as indicated by in vitro tests. Competition for limiting nutrients was thought to be the reason for the observed effects. PMID:3579281

  18. Metal immobilization in soils using synthetic zeolites.

    PubMed

    Oste, Leonard A; Lexmond, Theo M; Van Riemsdijk, Willem H

    2002-01-01

    In situ immobilization of heavy metals in contaminated soils is a technique to improve soil quality. Synthetic zeolites are potentially useful additives to bind heavy metals. This study selected the most effective zeolite in cadmium and zinc binding out of six synthetic zeolites (mordenite-type, faujasite-type, zeolite X, zeolite P, and two zeolites A) and one natural zeolite (clinoptilolite). Zeolite A appeared to have the highest binding capacity between pH 5 and 6.5 and was stable above pH 5.5. The second objective of this study was to investigate the effects of zeolite addition on the dissolved organic matter (DOM) concentration. Since zeolites increase soil pH and bind Ca, their application might lead to dispersion of organic matter. In a batch experiment, the DOM concentration increased by a factor of 5 when the pH increased from 6 to 8 as a result of zeolite A addition. A strong increase in DOM was also found in the leachate of soil columns, particularly in the beginning of the experiment. This resulted in higher metal leaching caused by metal-DOM complexes. In contrast, the free ionic concentration of Cd and Zn strongly decreased after the addition of zeolites, which might explain the reduction in metal uptake observed in plant growth experiments. Pretreatment of zeolites with acid (to prevent a pH increase) or Ca (to coagulate organic matter) suppressed the dispersion of organic matter, but also decreased the metal binding capacity of the zeolites due to competition of protons or Ca. PMID:12026084

  19. A green surfactant-assisted synthesis of hierarchical TS-1 zeolites with excellent catalytic properties for oxidative desulfurization.

    PubMed

    Du, Shuting; Li, Fen; Sun, Qiming; Wang, Ning; Jia, Mingjun; Yu, Jihong

    2016-02-25

    Hierarchical TS-1 zeolites with uniform intracrystalline mesopores have been successfully synthesized through the hydrothermal method by using the green and cheap surfactant Triton X-100 as the mesoporous template. The resultant materials exhibit remarkably enhanced catalytic activity in oxidative desulfurization reactions compared to the conventional TS-1 zeolite. PMID:26881277

  20. H-β Zeolite: an Efficient, Reusable Catalyst for One-Pot Synthesis of Isatins from Anilines.

    PubMed

    Raj, Victor Paul; Shaikh, Tanveer Mahamadali; Sudalai, Arumugam

    2010-06-01

    We describe a simple and highly efficient procedure for the single-step preparation of isatins from the commercially available anilines using H-β zeolite as a truly heterogeneous catalyst. H-β zeolite is readily separated from reaction mixture by simple filtration and reused several times without considerable loss of activity. PMID:24061745

  1. Preparation and characterization of activated carbon aerogel spheres

    NASA Astrophysics Data System (ADS)

    Liu, Ning; Liu, Fengshou

    2014-03-01

    Activated carbon aerogel spheres (A-CAS) were successfully prepared by imposing KOH activation on aerogel spheres. It was found that the activation treatment did not destroy the order of the surface of the carbon aerogel spheres (CAS), but it improved the pore structure and adsorption performance of the products. With increasing burn-off, the amount of mesopores first decreased and then increased, with the amount of micropores continuously increasing. The highest measured BET surface area and micropore surface area reached 1198 and 786 m2/g, respectively. The adsorption capacity of benzene organic vapour on the A-CAS is more than eight times as large as that on CAS.

  2. Porous texture evolution in Nomex-derived activated carbon fibers.

    PubMed

    Villar-Rodil, S; Denoyel, R; Rouquerol, J; Martínez-Alonso, A; Tascón, J M D

    2002-08-01

    In the present work, the textural evolution of a series of activated carbon fibers with increasing burn-off degree, prepared by the pyrolysis and steam activation of Nomex aramid fibers, is followed by measurements of physical adsorption of N(2) (77 K) and CO(2) (273 K) and immersion calorimetry into different liquids (dichloromethane, benzene, cyclohexane). The immersion calorimetry results are discussed in depth, paying special attention to the choice of the reference material. The activated carbon fibers studied possess an essentially homogeneous microporous texture, which suggests that these materials may be applied in gas separation, either directly or with additional CVD treatment. PMID:16290775

  3. Thermochemically activated carbon as an electrode material for supercapacitors.

    PubMed

    Ostafiychuk, Bogdan K; Budzulyak, Ivan M; Rachiy, Bogdan I; Vashchynsky, Vitalii M; Mandzyuk, Volodymyr I; Lisovsky, Roman P; Shyyko, Lyudmyla O

    2015-01-01

    The results of electrochemical studies of nanoporous carbon as electrode material for electrochemical capacitors (EC) are presented in this work. Nanoporous carbon material (NCM) was obtained from the raw materials of plant origin by carbonization and subsequent activation in potassium hydroxide. It is established that there is an optimal ratio of 1:1 between content of KOH and carbon material at chemical activation, while the maximum specific capacity of NCM is 180 F/g. An equivalent electrical circuit, which allows modeling of the impedance spectra in the frequency range of 10(-2) to 10(5) Hz, is proposed, and a physical interpretation of each element of the electrical circuit is presented. PMID:25852362

  4. Measured Enthalpies of Adsorption of Boron-Doped Activated Carbons

    NASA Astrophysics Data System (ADS)

    Beckner, M.; Romanos, J.; Dohnke, E.; Singh, A.; Schaeperkoetter, J.; Stalla, D.; Burress, J.; Jalisatgi, S.; Suppes, G.; Hawthorne, M. F.; Yu, P.; Wexler, C.; Pfeifer, P.

    2012-02-01

    There is significant interest in the properties of boron-doped activated carbons for their potential to improve hydrogen storage.ootnotetextMultiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage, P. Pfeifer et al. DOE Hydrogen Program 2011 Annual Progress Report, IV.C.3, 444-449 (2011). Boron-doped activated carbons have been produced using a process involving the pyrolysis of decaborane (B10H14) and subsequent high-temperature annealing. In this talk, we will present a systematic study of the effect of different boron doping processes on the samples' structure, hydrogen sorption, and surface chemistry. Initial room temperature experiments show a 20% increase in the hydrogen excess adsorption per surface area compared to the undoped material. Experimental enthalpies of adsorption will be presented for comparison to theoretical predictions for boron-doped carbon materials. Additionally, results from a modified version of the doping process will be presented.

  5. FENTON-DRIVEN REGENERATION OF GRANULAR ACTIVATED CARBON: A TECHNOLOGY OVERVIEW

    EPA Science Inventory

    A Fenton-driven mechanism for regenerating spent granular activated carbon (GAC) involves the combined, synergistic use of two reliable and well established treatment technologies - adsorption onto activated carbon and Fenton oxidation. During carbon adsorption treatment, enviro...

  6. Treatment of activated carbon to enhance catalytic activity for reduction of nitric oxide with ammonia

    SciTech Connect

    Ku, B.J.; Rhee, H.K. . Dept. of Chemical Engineering); Lee, J.K.; Park, D. )

    1994-11-01

    Catalytic activity of activated carbon treated with various techniques was examined in a fixed bed reactor for the reduction of nitric oxide with ammonia at 150 C. Activated carbon derived from coconut shell impregnated with an aqueous solution of ammonium sulfate, further treated with sulfuric acid, dried at 120 C, and then heated in an inert gas stream at 400 C, showed the highest catalytic activity within the range of experimental conditions. The enhancement of catalytic activity of modified activated carbon could be attributed to the increase in the amount of oxygen function groups which increased the adsorption site for ammonia. Catalytic activity of activated carbons depended on the surface area and the oxygen content as well.

  7. Bacteria associated with granular activated carbon particles in drinking water.

    PubMed Central

    Camper, A K; LeChevallier, M W; Broadaway, S C; McFeters, G A

    1986-01-01

    A sampling protocol was developed to examine particles released from granular activated carbon filter beds. A gauze filter/Swinnex procedure was used to collect carbon fines from 201 granular activated carbon-treated drinking water samples over 12 months. Application of a homogenization procedure (developed previously) indicated that 41.4% of the water samples had heterotrophic plate count bacteria attached to carbon particles. With the enumeration procedures described, heterotrophic plate count bacteria were recovered at an average rate of 8.6 times higher than by conventional analyses. Over 17% of the samples contained carbon particles colonized with coliform bacteria as enumerated with modified most-probable-number and membrane filter techniques. In some instances coliform recoveries were 122 to 1,194 times higher than by standard procedures. Nearly 28% of the coliforms attached to these particles in drinking water exhibited the fecal biotype. Scanning electron micrographs of carbon fines from treated drinking water showed microcolonies of bacteria on particle surfaces. These data indicate that bacteria attached to carbon fines may be an important mechanism by which microorganisms penetrate treatment barriers and enter potable water supplies. PMID:3767356

  8. Biofuel intercropping effects on soil carbon and microbial activity.

    PubMed

    Strickland, Michael S; Leggett, Zakiya H; Sucre, Eric B; Bradford, Mark A

    2015-01-01

    Biofuels will help meet rising demands for energy and, ideally, limit climate change associated with carbon losses from the biosphere to atmosphere. Biofuel management must therefore maximize energy production and maintain ecosystem carbon stocks. Increasingly, there is interest in intercropping biofuels with other crops, partly because biofuel production on arable land might reduce availability and increase the price of food. One intercropping approach involves growing biofuel grasses in forest plantations. Grasses differ from trees in both their organic inputs to soils and microbial associations. These differences are associated with losses of soil carbon when grasses become abundant in forests. We investigated how intercropping switchgrass (Panicum virgalum), a major candidate for cellulosic biomass production, in loblolly pine (Pinus taeda) plantations affects soil carbon, nitrogen, and microbial dynamics. Our design involved four treatments: two pine management regimes where harvest residues (i.e., biomass) were left in place or removed, and two switchgrass regimes where the grass was grown with pine under the same two biomass scenarios (left or removed). Soil variables were measured in four 1-ha replicate plots in the first and second year following switchgrass planting. Under switchgrass intercropping, pools of mineralizable and particulate organic matter carbon were 42% and 33% lower, respectively. These declines translated into a 21% decrease in total soil carbon in the upper 15 cm of the soil profile, during early stand development. The switchgrass effect, however, was isolated to the interbed region where switchgrass is planted. In these regions, switchgrass-induced reductions in soil carbon pools with 29%, 43%, and 24% declines in mineralizable, particulate, and total soil carbon, respectively. Our results support the idea that grass inputs to forests can prime the activity of soil organic carbon degrading microbes, leading to net reductions in stocks

  9. [Comparison study on adsorption of middle molecular substances with multiwalled carbon nanotubes and activated carbon].

    PubMed

    Li, Guifeng; Wan, Jianxin; Huang, Xiangqian; Zeng, Qiao; Tang, Jing

    2011-08-01

    In recent years, multi-walled carbon nanotubes (MWCTs) are very favorable to the adsorption of middle molecular substances in the hemoperfusion because of their multiporous structure, large surface area and high reactivity, which are beneficial to the excellent absorption properties. The purpose of this study was to study the MWCTs on the adsorption capacity of the middle molecular substances. Vitamin B12 (VB12) was selected as a model of the middle molecular substances. The morphologies of MWCTs and activated carbon from commercial "carbon kidney" were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The adsorption behavior of VB12 was compared to each other with UV-visible absorption spectra. The MWCTs formed a sophistaicate gap structure, and compared to the activated carbon, MWCTs had a larger surface area. By Langmuir equation and Freundlich equation fitting analysis, VB12 adsorption on MWCTs is fit for multi-molecular layer adsorption, and the adsorption type of activated carbon is more inclined to the model corresponding to Langmuir monolayer adsorption. The adsorption rate of MWCTs is faster than that of the activated carbon and the adsorption capacity is greater, which could be expected to become the new adsorbent in the hemoperfusion. PMID:21936376

  10. Carbon dioxide-activated carbons from almond tree pruning: Preparation and characterization

    NASA Astrophysics Data System (ADS)

    Gañán, J.; González, J. F.; González-García, C. M.; Ramiro, A.; Sabio, E.; Román, S.

    2006-06-01

    Activated carbons were prepared from almond tree pruning by non-catalytic and catalytic gasification with carbon dioxide and their surface characteristics were investigated. In both series a two-stage activation procedure (pyrolysis at 800 °C in nitrogen atmosphere, followed by carbon dioxide activation) was used for the production of activated samples. In non-catalytic gasification, the effect of the temperature (650-800 °C for 1 h) and the reaction time (1-12 h at 650 °C) on the surface characteristics of the prepared samples was investigated. Carbons were characterized by means of nitrogen adsorption isotherms at 77 K. The textural parameters of the carbons present a linear relation with the conversion degree until a value of approximately 40%, when they come independent from both parameters studied. The highest surface area obtained for this series was 840 m 2 g -1. In the catalytic gasification the effect of the addition of one catalyst (K and Co) and the gasification time (2-4 h) on the surface and porosity development of the carbons was also studied. At the same conditions, Co leads to higher conversion values than K but this last gives a better porosity development.

  11. A comparison of the electrochemical behavior of carbon aerogels and activated carbon fiber cloths

    SciTech Connect

    Tran, T.D.; Alviso, C.T.; Hulsey, S.S.; Nielsen, J.K.; Pekala, R.W.

    1996-05-10

    Electrochemical capacitative behavior of carbon aerogels and commercial carbon fiber cloths was studied in 5M KOH, 3M sulfuric acid, and 0.5M tetrethylammonium tetrafluoroborate/propylene carbonate electrolytes. The resorcinol-formaldehyde based carbon aerogels with a range of denisty (0.2-0.85 g/cc) have open-cell structures with ultrafine pore sizes (5-50 nm), high surface area (400-700 m{sup 2}/g), and a solid matrix composed of interconnected particles or fibers with characteristic diameters of 10 nm. The commercial fiber cloths in the density range 0.2-04g/cc have high surface areas (1000-2500 m{sup 2}/g). The volumetric capacitances of high-density aerogels are shown to be comparable to or exceeding those from activated carbon fibers. Electrochemical behavior of these materials in various electrolytes is compared and related to their physical properties.

  12. Magnetically Active Carbon Nanotubes at Work.

    PubMed

    Stopin, Antoine; Pineux, Florent; Marega, Riccardo; Bonifazi, Davide

    2015-06-22

    Endohedral and exohedral assembly of magnetic nanoparticles (MNPs) and carbon nanotubes (CNTs) recently gave birth to a large body of new hybrid nanomaterials (MNPs-CNTs) featuring properties that are otherwise not in reach with only the graphitic or metallic cores themselves. These materials feature enhanced magnetically guided motions (rotation and translation), magnetic saturation and coercivity, large surface area, and thermal stability. By guiding the reader through the most significant examples in this Concept paper, we describe how researchers in the field engineered and exploited the synergistic combination of these two types of nanoparticles in a large variety of current and potential applications, such as magnetic fluid hyperthermia therapeutics and in magnetic resonance imaging to name a few. PMID:26017389

  13. Selective Ring Opening of 1-Methylnaphthalene Over NiW-Supported Catalyst Using Dealuminated Beta Zeolite.

    PubMed

    Kim, Eun-Sang; Lee, You-Jin; Kim, Jeong-Rang; Kim, Joo-Wan; Kim, Tae-Wan; Chae, Ho-Jeong; Kim, Chul-Ung; Lee, Chang-Ha; Jeong, Soon-Yong

    2016-02-01

    Nanoporous Beta zeolite was dealuminated by weak acid treatment for reducing the acidity. Bi-functional catalysts were prepared using commercial Beta zeolites and the dealuminated zeolites for acidic function, NiW for metallic function. 1-Methylnaphthalene was selected as a model compound for multi-ring aromatics in heavy oil, and its selective ring opening reaction has been investigated using the prepared bi-functional catalysts with different acidity in fixed bed reaction system. The dealuminated Beta zeolites, which crystal structure and nanoporosity were maintained, showed the higher SiO2/Al2O3 ratio and smaller acidity than their original zeolite. NiW-supported catalyst using the dealuminated Beta zeolite with SiO2/Al203 mole ratio of 55 showed the highest performance for the selective ring opening. The acidity of catalyst seemed to play an important role as active sites for the selective ring opening of 1-methylnaphthalene but there should be some optimum catalyst acidity for the reaction. The acidity of Beta zeolite could be controlled by the acid treatment and the catalyst with the optimum acidity for the selective ring opening could be prepared. PMID:27433655

  14. Breakthrough CO₂ adsorption in bio-based activated carbons.

    PubMed

    Shahkarami, Sepideh; Azargohar, Ramin; Dalai, Ajay K; Soltan, Jafar

    2015-08-01

    In this work, the effects of different methods of activation on CO2 adsorption performance of activated carbon were studied. Activated carbons were prepared from biochar, obtained from fast pyrolysis of white wood, using three different activation methods of steam activation, CO2 activation and Potassium hydroxide (KOH) activation. CO2 adsorption behavior of the produced activated carbons was studied in a fixed-bed reactor set-up at atmospheric pressure, temperature range of 25-65°C and inlet CO2 concentration range of 10-30 mol% in He to determine the effects of the surface area, porosity and surface chemistry on adsorption capacity of the samples. Characterization of the micropore and mesopore texture was carried out using N2 and CO2 adsorption at 77 and 273 K, respectively. Central composite design was used to evaluate the combined effects of temperature and concentration of CO2 on the adsorption behavior of the adsorbents. The KOH activated carbon with a total micropore volume of 0.62 cm(3)/g and surface area of 1400 m(2)/g had the highest CO2 adsorption capacity of 1.8 mol/kg due to its microporous structure and high surface area under the optimized experimental conditions of 30 mol% CO2 and 25°C. The performance of the adsorbents in multi-cyclic adsorption process was also assessed and the adsorption capacity of KOH and CO2 activated carbons remained remarkably stable after 50 cycles with low temperature (160°C) regeneration. PMID:26257348

  15. A General Methodology for Evaluation of Carbon Sequestration Activities and Carbon Credits

    SciTech Connect

    Klasson, KT

    2002-12-23

    A general methodology was developed for evaluation of carbon sequestration technologies. In this document, we provide a method that is quantitative, but is structured to give qualitative comparisons despite changes in detailed method parameters, i.e., it does not matter what ''grade'' a sequestration technology gets but a ''better'' technology should receive a better grade. To meet these objectives, we developed and elaborate on the following concepts: (1) All resources used in a sequestration activity should be reviewed by estimating the amount of greenhouse gas emissions for which they historically are responsible. We have done this by introducing a quantifier we term Full-Cycle Carbon Emissions, which is tied to the resource. (2) The future fate of sequestered carbon should be included in technology evaluations. We have addressed this by introducing a variable called Time-adjusted Value of Carbon Sequestration to weigh potential future releases of carbon, escaping the sequestered form. (3) The Figure of Merit of a sequestration technology should address the entire life-cycle of an activity. The figures of merit we have developed relate the investment made (carbon release during the construction phase) to the life-time sequestration capacity of the activity. To account for carbon flows that occur during different times of an activity we incorporate the Time Value of Carbon Flows. The methodology we have developed can be expanded to include financial, social, and long-term environmental aspects of a sequestration technology implementation. It does not rely on global atmospheric modeling efforts but is consistent with these efforts and could be combined with them.

  16. Chars pyrolyzed from oil palm wastes for activated carbon preparation

    SciTech Connect

    Lua, A.C.; Guo, J.

    1999-01-01

    Chars pyrolyzed from extracted oil palm fibers for the preparation of activated carbons were studied. The effects of pyrolysis temperature and hold time on density, porosity, yield, BET and micropore surface areas, total pore volume, and pore size distributions of chars were investigated. The optimum conditions for pyrolysis were found to be at a pyrolysis temperature of 850 C for a hold time of 3.5 h. Scanning electron micrographs of the char surfaces verified the presence of porosities. The experimental results showed that it was feasible to produce chars with high BET and micropore surface areas from extracted oil palm fibers. The resulting chars will be subjected to steam or carbon dioxide activation to prepare activated carbons for use as gas adsorbents for air pollution control.

  17. Modified Activated Carbon to be Used in Clinical Applications

    NASA Astrophysics Data System (ADS)

    Fernando, M. S.; de Silva, W. R. M.; de Silva, K. M. N.

    2014-11-01

    In this study a novel nano composite of hydroxyapatite nano particles impregnated activated carbon (C-HAp), which was synthesized in our own method, was used in iron adsorption studies. The study was conducted in order to investigate the potential of using C-HAp nanocomposite to be used in clinical detoxifications such as acute iron toxicity where the use of Activated carbon (GAC) is not very effective. Adsorption studies were conducted for synthetic solutions of Fe2+, Fe3+ and iron syrup using GAC, C-HAp and neat HAp as adsorbents. According to the results C-HAp nano composite showed improved properties than GAC in adsorbing Fe2+, Fe3+ and also Fe ions in iron syrup solutions. Thus the results of the in-vitro studies of iron adsorption studies indicated the potential of using C-HAp as an alternative to activated carbon in such clinical applications.

  18. Impact of sulfur oxides on mercury capture by activated carbon.

    PubMed

    Presto, Albert A; Granite, Evan J

    2007-09-15

    Recent field tests of mercury removal with activated carbon injection (ACI) have revealed that mercury capture is limited in flue gases containing high concentrations of sulfur oxides (SOx). In order to gain a more complete understanding of the impact of SOx on ACl, mercury capture was tested under varying conditions of SO2 and SO3 concentrations using a packed bed reactor and simulated flue gas (SFG). The final mercury content of the activated carbons is independent of the SO2 concentration in the SFG, but the presence of SO3 inhibits mercury capture even at the lowest concentration tested (20 ppm). The mercury removal capacity decreases as the sulfur content of the used activated carbons increases from 1 to 10%. In one extreme case, an activated carbon with 10% sulfur, prepared by H2SO4 impregnation, shows almost no mercury capacity. The results suggest that mercury and sulfur oxides are in competition for the same binding sites on the carbon surface. PMID:17948811

  19. Impact of sulfur oxides on mercury capture by activated carbon

    SciTech Connect

    Albert A. Presto; Evan J. Granite

    2007-09-15

    Recent field tests of mercury removal with activated carbon injection (ACI) have revealed that mercury capture is limited in flue gases containing high concentrations of sulfur oxides (SOx). In order to gain a more complete understanding of the impact of SOx on ACI, mercury capture was tested under varying conditions of SO{sub 2} and SO{sub 3} concentrations using a packed bed reactor and simulated flue gas (SFG). The final mercury content of the activated carbons is independent of the SO{sub 2} concentration in the SFG, but the presence of SO{sub 3} inhibits mercury capture even at the lowest concentration tested (20 ppm). The mercury removal capacity decreases as the sulfur content of the used activated carbons increases from 1 to 10%. In one extreme case, an activated carbon with 10% sulfur, prepared by H{sub 2}SO{sub 4} impregnation, shows almost no mercury capacity. The results suggest that mercury and sulfur oxides are in competition for the same binding sites on the carbon surface. 30 refs., 3 figs., 2 tabs.

  20. UTILITY OF ZEOLITES IN HAZARDOUS METAL REMOVAL FROM WATER

    EPA Science Inventory

    Zeolites are well known for their ion exchange, adsorption and acid catalysis properties. Different inorganic pollutants have been removed from water at room temperature by using synthetic zeolites. Zeolite Faujasite Y has been used to remove inorganic pollutants including arseni...

  1. Synthesis and characterization of hydrophobic zeolite for the treatment of hydrocarbon contaminated ground water.

    PubMed

    Northcott, Kathy A; Bacus, Joannelle; Taya, Naoyuki; Komatsu, Yu; Perera, Jilska M; Stevens, Geoffrey W

    2010-11-15

    Hydrophobic zeolite was synthesized, modified and characterized for its suitability as a permeable reactive barrier (PRB) material for treatment of hydrocarbons in groundwater. Batch sorption tests were performed along with a number of standard characterization techniques. High and low ionic strength and pH tests were also conducted to determine their impact on hydrocarbon uptake. Further ion exchange tests were conducted to determine the potential for the zeolite to act as both a hydrocarbon capture material and nutrient a delivery system for bioremediation. The zeolite was coated with octadecyltrichlorosilane (C18) to change its surface properties. The results of the surface characterization tests showed that the underlying zeolite structure was largely unaffected by the coating. TGA measurements showed a reactive carbon content of 1-2%. Hydrocarbon (o-xylene and naphthalene) sorption isotherms results compared well with the behaviour of similar materials investigated by other researchers. Ionic strength and pH had little effect on hydrocarbon sorption and the treated zeolite had an ion exchange capacity of 0.3 mequiv./g, indicating it could be utilised as a nutrient source in PRBs. Recycle tests indicated that the zeolite could be used cleaned and reused at least three times without significant reduction in treatment effectiveness. PMID:20688431

  2. The growth of zeolites A, X and mordenite in space

    NASA Technical Reports Server (NTRS)

    Sacco, Albert, Jr.; Bac, N.; Coker, E. N.; Dixon, A. G.; Warzywoda, J.; Thompson, R. W.

    1994-01-01

    Zeolites are a class of crystalline aluminosilicate materials that form the backbone of the chemical process industry worldwide. They are used primarily as adsorbents and catalysts and support to a significant extent the positive balance of trade realized by the chemical industry in the United States (around $19 billion in 1991). The magnitude of their efforts can be appreciated when one realizes that since their introduction as 'cracking catalysts' in the early 1960's, they have saved the equivalent of 60 percent of the total oil production from Alaska's North Slope. Thus the performance of zeolite catalysts can have a profound effect on the U.S. economy. It is estimated that a 1 percent increase in yield of the gasoline fraction per barrel of oil would represent a savings of 22 million barrels of crude oil per year, representing a reduction of $400 million in the United States' balance of payments. Thus any activity that results in improvement in zeolite catalyst performance is of significant scientific and industrial interest. In addition, due to their 'stability,' uniformity, and, within limits, their 'engineerable' structures, zeolites are being tested as potential adsorbents to purify gases and liquids at the parts-per-billion levels needed in today's electronic, biomedical, and biotechnology industries and for the environment. Other exotic applications, such as host materials for quantum-confined semiconductor atomic arrays, are also being investigated. Because of the importance of this class of material, extensive efforts have been made to characterize their structures and to understand their nucleation and growth mechanisms, so as to be able to custom-make zeolites for a desired application. To date, both the nucleation mechanics and chemistry (such as what are the 'key' nutrients) are, as yet, still unknown for many, if not all, systems. The problem is compounded because there is usually a 'gel' phase present that is assumed to control the degree of

  3. Unique properties of silver cations in solid-acid catalysis by zeolites and heteropolyacids.

    PubMed

    Ono, Yoshio; Baba, Toshihide

    2015-06-28

    Ag(+)-exchanged zeolites exhibit unique catalytic properties caused by the combination of their redox and acidic properties. Partial reduction of Ag(+) ions in zeolites with hydrogen leads to the formation of acidic protons and silver metal particles, which can be observed using X-ray powder diffraction patterns (XRD). By simply evacuating hydrogen from the system, the silver metal particles are returned back to Ag(+) ions and at the same time, acidic protons are eliminated. This interconversion of Ag(+) ions and silver metal or gaseous hydrogen and surface protons is reflexed in the catalytic activities of Ag(+)-exchanged zeolites for acid-catalyzed reactions: the activity of Ag(+)-exchanged Y zeolite (Ag-Y) reversibly changes with the partial pressure of hydrogen. Furthermore, the activity of Ag-Y in the presence of hydrogen is higher than that of H(+)-exchanged Y zeolite (H-Y). Similar phenomena are also observed for the silver salt of dodecatungstophosphoric acid (Ag3PW12O40). Ag(+)-exchanged ZSM-5 zeolite (Ag-ZSM-5) is a very selective catalyst for aromatization of alkanes, alkenes and methanol. Examination of the activation step of lower alkanes revealed that Ag(+) ions dramatically enhance the dehydrogenation of the alkanes via heterolytic dissociation of the alkanes into carbenium ions and hydride species. Ag(+)-exchanged zeolites can also activate methane. The reaction of methane with ethene and benzene gives propene and toluene, respectively. Ag-ZSM-5 is a very stable catalyst under hydrothermal conditions because of the interconversion properties of Ag(+) ions and silver metal in the zeolite. PMID:26018842

  4. Adsorption of naphthenic acids on high surface area activated carbons.

    PubMed

    Iranmanesh, Sobhan; Harding, Thomas; Abedi, Jalal; Seyedeyn-Azad, Fakhry; Layzell, David B

    2014-01-01

    In oil sands mining extraction, water is an essential component; however, the processed water becomes contaminated through contact with the bitumen at high temperature, and a portion of it cannot be recycled and ends up in tailing ponds. The removal of naphthenic acids (NAs) from tailing pond water is crucial, as they are corrosive and toxic and provide a substrate for microbial activity that can give rise to methane, which is a potent greenhouse gas. In this study, the conversion of sawdust into an activated carbon (AC) that could be used to remove NAs from tailings water was studied. After producing biochar from sawdust by a slow-pyrolysis process, the biochar was physically activated using carbon dioxide (CO2) over a range of temperatures or prior to producing biochar, and the sawdust was chemically activated using phosphoric acid (H3PO4). The physically activated carbon had a lower surface area per gram than the chemically activated carbon. The physically produced ACs had a lower surface area per gram than chemically produced AC. In the adsorption tests with NAs, up to 35 mg of NAs was removed from the water per gram of AC. The chemically treated ACs showed better uptake, which can be attributed to its higher surface area and increased mesopore size when compared with the physically treated AC. Both the chemically produced and physically produced AC provided better uptake than the commercially AC. PMID:24766592

  5. Application of hierarchical MFI zeolite for the catalytic pyrolysis of Japanese larch.

    PubMed

    Park, Kyu-Hong; Park, Hyun Ju; Kim, Jeongnam; Ryoo, Ryong; Jeon, Jong-Ki; Park, Junhong; Park, Young-Kwon

    2010-01-01

    The catalytic pyrolysis of Japanese larch was carried out over a hierarchical MFI zeolite (Meso MFI C16). The zeolite was synthesized using an amphiphilic organosilane as a mesopore-directing agent, and its catalytic activity was compared with that of the conventional HZSM-5 and the mesoporous material from HZSM-5 (MMZ(ZSM-5)). The effect of the hierarchical MFI zeolite on the product distribution and chemical composition of the bio-oil was also examined. The hierarchical MFI zeolite exhibited the highest activity in deoxygenation and aromatization during the catalytic pyrolysis of Japanese larch. In particular, it showed high selectivity for valuable aromatics, such as benzene, toluene, and xylenes (BTX), even though it decreased the organic fraction of bio-oil. Its higher mesoporosity resulted, however, in an increase in the coke amount and in undesirable products, such as polycyclic aromatic hydrocarbons (PAHs). PMID:20352861

  6. Hydrothermal alteration and zeolitization of the Fohberg phonolite, Kaiserstuhl Volcanic Complex, Germany

    NASA Astrophysics Data System (ADS)

    Weisenberger, Tobias Björn; Spürgin, Simon; Lahaye, Yann

    2014-11-01

    The subvolcanic Fohberg phonolite (Kaiserstuhl Volcanic Complex, Germany) is an economic zeolite deposit, formed by hydrothermal alteration of primary magmatic minerals. It is mined due to the high (>40 wt%) zeolite content, which accounts for the remarkable zeolitic physicochemical properties of the ground rock. New mineralogical and geochemical studies are carried out (a) to evaluate the manifestation of hydrothermal alteration, and (b) to constrain the physical and chemical properties of the fluids, which promoted hydrothermal replacement. The alkaline intrusion is characterized by the primary mineralogy: feldspathoid minerals, K-feldspar, aegirine-augite, wollastonite, and andradite. The rare-earth elements-phase götzenite is formed during the late-stage magmatic crystallization. Fluid-induced re-equilibration of feldspathoid minerals and wollastonite caused breakdown to a set of secondary phases. Feldspathoid minerals are totally replaced by various zeolite species, calcite, and barite. Wollastonite breakdown results in the formation of various zeolites, calcite, pectolite, sepiolite, and quartz. Zeolites are formed during subsolidus hydrothermal alteration (<150 °C) under alkaline conditions. A sequence of Ca-Na-dominated zeolite species (gonnardite, thomsonite, mesolite) is followed by natrolite. The sequence reflects an increase in and decrease in of the precipitating fluid. Low radiogenic 87Sr/86Sr values indicate a local origin of the elements necessary for secondary mineral formation from primary igneous phases. In addition, fractures cut the intrusive body, which contain zeolites, followed by calcite and a variety of other silicates, carbonates, and sulfates as younger generations. Stable isotope analysis of late-fracture calcite indicates very late circulation of meteoric fluids and mobilization of organic matter from surrounding sedimentary units.

  7. Removal of benzocaine from water by filtration with activated carbon

    USGS Publications Warehouse

    Howe, G.E.; Bills, T.D.; Marking, L.L.

    1990-01-01

    Benzocaine is a promising candidate for registration with the U.S. Food and Drug Administration for use as an anesthetic in fish culture, management, and research. A method for the removal of benzocaine from hatchery effluents could speed registration of this drug by eliminating requirements for data on its residues, tolerances, detoxification, and environmental hazards. Carbon filtration effectively removes many organic compounds from water. This study tested the effectiveness of three types of activated carbon for removing benzocaine from water by column filtration under controlled laboratory conditions. An adsorptive capacity was calculated for each type of activated carbon. Filtrasorb 400 (12 x 40 mesh; U.S. standard sieve series) showed the greatest capacity for benzocaine adsorption (76.12 mg benzocaine/g carbon); Filtrasorb 300 (8 x 30 mesh) ranked next (31.93 mg/g); and Filtrasorb 816 (8 x 16 mesh) absorbed the least (1.0 mg/g). Increased adsorptive capacity was associated with smaller carbon particle size; however, smaller particle size also impeded column flow. Carbon filtration is a practical means for removing benzocaine from treated water.

  8. Improved granular activated carbon for the stabilization of wastewater PH

    SciTech Connect

    Farmer, R.W.; Dussert, B.W.; Kovacic, S.L.

    1996-12-31

    Laboratory studies have identified the cause of the pH rise, which occurs during water treatment with activated carbon, as an interaction between the naturally occurring anions and protons in the water and the carbon surface. The interaction can be described as an ion exchange type of phenomenon, in which the carbon surface sorbs the anions and corresponding hydronium ions from the water. These studies have shown that the anion sorption and resulting pH increase is independent of the raw material used for the activated carbon production, e.g. bituminous or subbituminous coal, peat, wood or coconut. Also, the pH excursions occur with virgin, reactivated, and acid washed granular carbons. Current pH control technologies focus on adjustment of the wastewater pH prior to discharge or recycle of the initial effluent water until the pH increase abates. However, improved water pH control options have been realized by altering the carbon surface through controlled oxidation rather than the water chemistry or extended preprocessing at the treatment site.

  9. Iron-phthalocyanine immobilized on activated carbon black: A selective catalyst for alkane oxidation

    SciTech Connect

    Parton, R.F.; Neys, P.E.; Jacobs, P.A.

    1996-12-01

    Carbon black is tested as a support for iron-phthalocyanine within the frame of the oxidation of hydrocarbons with t-butyl-hydroperoxide as oxygen donor. The increased hydrophobicity of the carrier surface, with respect to zeolite Y, changes the adsorption behavior of the components in the reaction mixture towards the alkane. A major improvement in the oxidation conversion and efficiency of cyclohexane has been established. Furthermore, the kinetic isotope effect and the reactivity order of secondary and tertiary carbon atoms measured with adamantane provide evidence for an {open_quotes}oxygen rebound{close_quotes} reaction mechanism, a non-free-radical oxidation pathway where the metallo-complex is responsible for the hydrogen abstraction. 40 refs., 7 figs., 2 tabs.

  10. Oxidation of bioethanol using zeolite-encapsulated gold nanoparticles.

    PubMed

    Mielby, Jerrik; Abildstrøm, Jacob Oskar; Wang, Feng; Kasama, Takeshi; Weidenthaler, Claudia; Kegnaes, Søren

    2014-11-10

    With the ongoing developments in biomass conversion, the oxidation of bioethanol to acetaldehyde may become a favorable and green alternative to the preparation from ethylene. Here, a simple and effective method to encapsulate gold nanoparticles in zeolite silicalite-1 is reported and their high activity and selectivity for the catalytic gas-phase oxidation of ethanol are demonstrated. The zeolites are modified by a recrystallization process, which creates intraparticle voids and mesopores that facilitate the formation of small and disperse nanoparticles upon simple impregnation. The individual zeolite crystals comprise a broad range of mesopores and contain up to several hundred gold nanoparticles with a diameter of 2-3 nm that are distributed inside the zeolites rather than on the outer surface. The encapsulated nanoparticles have good stability and result in 50 % conversion of ethanol with 98 % selectivity toward acetaldehyde at 200 °C, which (under the given reaction conditions) corresponds to 606 mol acetaldehyde/mol Au hour(-1) . PMID:25196739

  11. Synthesis of mesoporous zeolite single crystals with cheap porogens

    NASA Astrophysics Data System (ADS)

    Tao, Haixiang; Li, Changlin; Ren, Jiawen; Wang, Yanqin; Lu, Guanzhong

    2011-07-01

    Mesoporous zeolite (silicalite-1, ZSM-5, TS-1) single crystals have been successfully synthesized by adding soluble starch or sodium carboxymethyl cellulose (CMC) to a conventional zeolite synthesis system. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen sorption analysis, 27Al magic angle spinning nuclear magnetic resonance ( 27Al MAS NMR), temperature-programmed desorption of ammonia (NH 3-TPD) and ultraviolet-visible spectroscopy (UV-vis). The SEM images clearly show that all zeolite crystals possess the similar morphology with particle size of about 300 nm, the TEM images reveal that irregular intracrystal pores are randomly distributed in the whole crystal. 27Al MAS NMR spectra indicate that nearly all of the Al atoms are in tetrahedral co-ordination in ZSM-5, UV-vis spectra confirm that nearly all of titanium atoms are incorporated into the framework of TS-1. The catalytic activity of meso-ZSM-5 in acetalization of cyclohexanone and meso-TS-1 in hydroxylation of phenol was also studied. The synthesis method reported in this paper is cost-effective and environmental friendly, can be easily expended to prepare other hierarchical structured zeolites.

  12. Carbon-Based Supercapacitors Produced by Activation of Graphene

    SciTech Connect

    Zhu, Y.; Su, D.; Murali, S.; Stoller, M.D.; Ganesh, K.J.; Cai, W.; Ferreira, P.J.; Pirkle, A.; Wallace, R.M.; Cychosz, K.A., Thommes, M.; Stach, E.A.; Ruoff, R.S.

    2011-06-24

    Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp{sup 2}-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

  13. Carbon-based Supercapacitors Produced by Activation of Graphene

    SciTech Connect

    Y Zhu; S Murali; M Stoller; K Ganesh; W Cai; P Ferreira; A Pirkle; R Wallace; K Cychosz; et al.

    2011-12-31

    Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp{sup 2}-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

  14. Effect of the Si/Al ratio and of the zeolite structure on the performance of dealuminated zeolites for the reforming of hydrocarbon mixtures

    SciTech Connect

    Smirniotis, P.G.; Zhang, W.

    1996-09-01

    Various 12-membered ring pore zeolites were employed for the reforming of synthetic hydrocarbon mixtures which simulate industrial naphthas. All the zeolites were dealuminated to various extents. It was found that, under the present conditions over the samples which are slightly dealuminated, bimolecular-condensation reactions followed by recracking are responsible for the relatively large selectivities of C{sub 4} paraffins. The monomolecular cracking (via pentacoordinated carbonium ions) of the latter hydrocarbons is responsible for the large generation of CH{sub 4} from the cracking of C{sub 4} paraffins. When the Si/Al ratio increases, the selectivity of methane passes through a steep minimum, while those of C{sub 3}, C{sub 4}, and C{sub 5} pass through a maximum. It was also found that the zeolite pore structure is a very important factor for the time on stream activity of zeolite-based catalysts. Zeolites with reduced aluminum content and pore structures, which do not favor the formation of coke precursors in their cavities, can lead to very promising catalysts for acid-catalyzed reactions. From this study a 12-membered ring pore zeolite, which demonstrates minimal coke deactivation, was identified.

  15. Zeolite in horizontal permeable reactive barriers for artificial groundwater recharge

    NASA Astrophysics Data System (ADS)

    Leal, María; Martínez-Hernández, Virtudes; Lillo, Javier; Meffe, Raffaella; de Bustamante, Irene

    2013-04-01

    The Spanish Water Reuse Royal Decree 1620/2007 considers groundwater recharge as a feasible use of reclaimed water. To achieve the water quality established in the above-mentioned legislation, a tertiary wastewater treatment is required. In this context, the infiltration of effluents generated by secondary wastewater treatments through a Horizontal Permeable Reactive Barrier (HPRB) may represent a suitable regeneration technology. Some nutrients (phosphate and ammonium) and some Pharmaceutical and Personal Care Products (PPCPs) are not fully removed in conventional wastewater treatment plants. To avoid groundwater contamination when effluents of wastewater treatments plants are used in artificial recharge activities, these contaminants have to be removed. Due to its sorption capacities, zeolite is among the most used reactive materials in Permeable Reactive Barrier (PRB). Therefore, the main goal of this study is to evaluate the zeolite retention effectiveness of nutrients and PPCPs occurring in treated wastewater. Batch sorption experiments using synthetic wastewater (SWW) and zeolite were performed. A 1:4 zeolite/SWW ratio was selected due to the high sorption capacity of the reactive material.The assays were carried out by triplicate. All the bottles containing the SWW-zeolite mixture were placed on a mechanical shaker during 24 hours at 140 rpm and 25 °C. Ammonium and phosphate, as main nutrients, and a group of PPCPs were selected as compounds to be tested during the experiments. Nutrients were analyzed by ion chromatography. For PPCPs determination, Solid Phase Extraction (SPE) was applied before their analysis by liquid chromatography-mass spectrometry time of flight (LC-MS/ TOF). The experimental data were fitted to linearized Langmuir and Freundlich isotherm equations to obtain sorption parameters. In general, Freundlich model shows a greater capability of reproducing experimental data. To our knowledge, sorption of the investigated compounds on zeolite

  16. Pore structure of the activated coconut shell charcoal carbon

    NASA Astrophysics Data System (ADS)

    Budi, E.; Nasbey, H.; Yuniarti, B. D. P.; Nurmayatri, Y.; Fahdiana, J.; Budi, A. S.

    2014-09-01

    The development of activated carbon from coconut shell charcoal has been investigated by using physical method to determine the influence of activation parameters in term of temperature, argon gas pressure and time period on the pore structure of the activated carbon. The coconut shell charcoal was produced by pyrolisis process at temperature of about 75 - 150 °C for 6 hours. The charcoal was activated at various temperature (532, 700 and 868 °C), argon gas pressure (6.59, 15 and 23.4 kgf/cm2) and time period of (10, 60 and 120 minutes). The results showed that the pores size were reduced and distributed uniformly as the activation parameters are increased.

  17. Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results

    SciTech Connect

    Mattigod, Shas V.; Wellman, Dawn M.; Golovich, Elizabeth C.; Cordova, Elsa A.; Smith, Ronald M.

    2010-12-01

    CH2M HILL Plateau Remediation Company (CHPRC) is currently developing a 200-West Area groundwater pump-and-treat system as the remedial action selected under the Comprehensive Environmental Response, Compensation, and Liability Act Record of Decision for Operable Unit (OU) 200-ZP-1. This report documents the results of treatability tests Pacific Northwest National Laboratory researchers conducted to quantify the ability of selected activated carbon products (or carbons) to adsorb technetium-99 (Tc-99) from 200-West Area groundwater. The Tc-99 adsorption performance of seven activated carbons (J177601 Calgon Fitrasorb 400, J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, J177612 Norit GAC830, J177613 Norit GAC830, and J177617 Nucon LW1230) were evaluated using water from well 299-W19-36. Four of the best performing carbons (J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, and J177613 Norit GAC830) were selected for batch isotherm testing. The batch isotherm tests on four of the selected carbons indicated that under lower nitrate concentration conditions (382 mg/L), Kd values ranged from 6,000 to 20,000 mL/g. In comparison. Under higher nitrate (750 mg/L) conditions, there was a measureable decrease in Tc-99 adsorption with Kd values ranging from 3,000 to 7,000 mL/g. The adsorption data fit both the Langmuir and the Freundlich equations. Supplemental tests were conducted using the two carbons that demonstrated the highest adsorption capacity to resolve the issue of the best fit isotherm. These tests indicated that Langmuir isotherms provided the best fit for Tc-99 adsorption under low nitrate concentration conditions. At the design basis concentration of Tc 0.865 µg/L(14,700 pCi/L), the predicted Kd values from using Langmuir isotherm constants were 5,980 mL/g and 6,870 mL/g for for the two carbons. These Kd values did not meet the target Kd value of 9,000 mL/g. Tests

  18. Molybdenum Speciation and its Impact on Catalytic Activity during Methane Dehydroaromatization in Zeolite ZSM-5 as Revealed by Operando X-Ray Methods.

    PubMed

    Lezcano-González, Inés; Oord, Ramon; Rovezzi, Mauro; Glatzel, Pieter; Botchway, Stanley W; Weckhuysen, Bert M; Beale, Andrew M

    2016-04-18

    Combined high-resolution fluorescence detection X-ray absorption near-edge spectroscopy, X-ray diffraction, and X-ray emission spectroscopy have been employed under operando conditions to obtain detailed new insight into the nature of the Mo species on zeolite ZSM-5 during methane dehydroaromatization. The results show that isolated Mo-oxo species present after calcination are converted by CH4 into metastable MoCx Oy species, which are primarily responsible for C2 Hx /C3 Hx formation. Further carburization leads to MoC3 clusters, whose presence coincides with benzene formation. Both sintering of MoC3 and accumulation of large hydrocarbons on the external surface, evidenced by fluorescence-lifetime imaging microscopy, are principally responsible for the decrease in catalytic performance. These results show the importance of controlling Mo speciation to achieve the desired product formation, which has important implications for realizing the impact of CH4 as a source for platform chemicals. PMID:26990500

  19. Acid-Base Pairs in Lewis Acidic Zeolites Promote Direct Aldol Reactions by Soft Enolization.

    PubMed

    Lewis, Jennifer D; Van de Vyver, Stijn; Román-Leshkov, Yuriy

    2015-08-17

    Hf-, Sn-, and Zr-Beta zeolites catalyze the cross-aldol condensation of aromatic aldehydes with acetone under mild reaction conditions with near quantitative yields. NMR studies with isotopically labeled molecules confirm that acid-base pairs in the Si-O-M framework ensemble promote soft enolization through α-proton abstraction. The Lewis acidic zeolites maintain activity in the presence of water and, unlike traditional base catalysts, in acidic solutions. PMID:26138135

  20. Atypical Hydrogen Uptake on Chemically Activated, Ultramicroporous Carbon

    SciTech Connect

    Bhat, Vinay V; Contescu, Cristian I; Gallego, Nidia C; Baker, Frederick S

    2010-01-01

    Hydrogen adsorption at near-ambient temperatures on ultramicroporous carbon (UMC), derived through secondary chemical activation from a wood-based activated carbon was studied using volumetric and gravimetric methods. The results showed that physisorption is accompanied by a process of different nature that causes slow uptake at high pressures and hysteresis on desorption. In combination, this results in unusually high levels of hydrogen uptake at near-ambient temperatures and pressures (e.g. up to 0.8 wt % at 25 oC and 2 MPa). The heat of adsorption corresponding to the slow process leading to high uptake (17 20 kJ/mol) is higher than usually reported for carbon materials, but the adsorption kinetics is slow, and the isotherms exhibit pronounced hysteresis. These unusual properties were attributed to contributions from polarization-enhanced physisorption caused by traces of alkali metals residual from chemical activation. The results support the hypothesis that polarization-induced physisorption in high surface area carbons modified with traces of alkali metal ions is an alternate route for increasing the hydrogen storage capacity of carbon adsorbents.

  1. Effects of organic carbon sequestration strategies on soil enzymatic activities

    NASA Astrophysics Data System (ADS)

    Puglisi, E.; Suciu, N.; Botteri, L.; Ferrari, T.; Coppolecchia, D.; Trevisan, M.; Piccolo, A.

    2009-04-01

    Greenhouse gases emissions can be counterbalanced with proper agronomical strategies aimed at sequestering carbon in soils. These strategies must be tested not only for their ability in reducing carbon dioxide emissions, but also for their impact on soil quality: enzymatic activities are related to main soil ecological quality, and can be used as early and sensitive indicators of alteration events. Three different strategies for soil carbon sequestration were studied: minimum tillage, protection of biodegradable organic fraction by compost amendment and oxidative polimerization of soil organic matter catalyzed by biometic porfirins. All strategies were compared with a traditional agricultural management based on tillage and mineral fertilization. Experiments were carried out in three Italian soils from different pedo-climatic regions located respectively in Piacenza, Turin and Naples and cultivated with maize or wheat. Soil samples were taken for three consecutive years after harvest and analyzed for their content in phosphates, ß-glucosidase, urease and invertase. An alteration index based on these enzymatic activities levels was applied as well. The biomimetic porfirin application didn't cause changes in enzymatic activities compared to the control at any treatment or location. Enzymatic activities were generally higher in the minimum tillage and compost treatment, while differences between location and date of samplings were limited. Application of the soil alteration index based on enzymatic activities showed that soils treated with compost or subjected to minimum tillage generally have a higher biological quality. The work confirms the environmental sustainability of the carbon sequestering agronomical practices studied.

  2. Production Scale-Up or Activated Carbons for Ultracapacitors

    SciTech Connect

    Dr. Steven D. Dietz

    2007-01-10

    Transportation use accounts for 67% of the petroleum consumption in the US. Electric and hybrid vehicles are promising technologies for decreasing our dependence on petroleum, and this is the objective of the FreedomCAR & Vehicle Technologies Program. Inexpensive and efficient energy storage devices are needed for electric and hybrid vehicle to be economically viable, and ultracapacitors are a leading energy storage technology being investigated by the FreedomCAR program. The most important parameter in determining the power and energy density of a carbon-based ultracapacitor is the amount of surface area accessible to the electrolyte, which is primarily determined by the pore size distribution. The major problems with current carbons are that their pore size distribution is not optimized for liquid electrolytes and the best carbons are very expensive. TDA Research, Inc. (TDA) has developed methods to prepare porous carbons with tunable pore size distributions from inexpensive carbohydrate based precursors. The use of low-cost feedstocks and processing steps greatly lowers the production costs. During this project with the assistance of Maxwell Technologies, we found that an impurity was limiting the performance of our carbon and the major impurity found was sulfur. A new carbon with low sulfur content was made and found that the performance of the carbon was greatly improved. We also scaled-up the process to pre-production levels and we are currently able to produce 0.25 tons/year of activated carbon. We could easily double this amount by purchasing a second rotary kiln. More importantly, we are working with MeadWestvaco on a Joint Development Agreement to scale-up the process to produce hundreds of tons of high quality, inexpensive carbon per year based on our processes.

  3. [Preparation and optimum process of walnut peel activated carbon by zinc chloride as activating agent].

    PubMed

    Liu, Xiao-hong; Wang, Xing-wei; Zhao, Bo; Lü, Jun-fang; Kang, Ni-na; Zhang, Yao-jun

    2014-12-01

    Walnut peel as raw material, zinc chloride was used as activating agent for preparation walnut peel activated carbon in the muffle furnace in this experiment, using orthogonal design. Yield, the specific surface area and iodine number of walnut peel activated carbon were determined at all designed experimental conditions and the optimum technological condition of preparation was obtained. By analysis of aperture, infrared spectra and the content of acidic group in surface with Boehm, walnut peel activated carbon of prepared at the optimum condition was characterized. The results showed the optimum technological parameters of preparation: activation temperature (600 °C), activation time (1 h), the concentration of zinc chloride (50%), the particle size (60 mesh). The specific surface area of walnut peel activated carbon obtained at optimum condition was mounting to 1258.05 m2 · g(-1), the ratio of medium porous 32.18%. Therefore, walnut peel can be used in the preparation of the high-quality activated carbon of large surface area. Agricultural wastes, as walnut peel, not only were implemented recycle, but also didn't make any pollution. Meanwhile, a cheap adsorbent was provided and it was of great significance to open a new source of activated carbon. PMID:25881437

  4. A MOF-derived Co-CoO@N-doped porous carbon for efficient tandem catalysis: dehydrogenation of ammonia borane and hydrogenation of nitro compounds.

    PubMed

    Ma, Xiao; Zhou, Yu-Xiao; Liu, Hang; Li, Yang; Jiang, Hai-Long

    2016-06-01

    The one-step pyrolysis of a zeolite-type metal-organic framework, Co(2-methylimidazole)2 (ZIF-67), produces an N-doped porous carbon incorporating well-dispersed Co/CoO nanoparticles, which exhibit excellent catalytic activity, chemoselectivity and magnetic recyclability for the tandem dehydrogenation of ammonia borane and hydrogenation of nitro compounds at room temperature. PMID:27241630

  5. Synthesis and characterization of activated carbon from asphalt

    NASA Astrophysics Data System (ADS)

    Kandah, Munther Issa; Shawabkeh, Reyad; Al-Zboon, Mahmoud Ar'ef

    2006-11-01

    Asphalt (cheap and available in huge amount in Jordan) was converted into activated carbon powder by chemical treatment with sulphuric and nitric acids at 450 °C. The final product was characterized and found effective as adsorbent material. Its cation exchange capacity reaches 191.2 meq/100-g carbons when treated with 30 wt% acid/asphalt ratio without airflow rate injection and 208 meq/100-g carbons when 6.5 ml air/min was injected into the surface of the asphalt during activation at the same acid/asphalt weight ratio of 30 and temperature 450 °C. The zero point of charge for this product was found to be stable at pH value around 3 in the range of initial pH between 3 and 10.

  6. Carbon Beam Radio-Therapy and Research Activities at HIMAC

    NASA Astrophysics Data System (ADS)

    Kanazawa, Mitsutaka

    2007-05-01

    Radio-therapy with carbon ion beam has been carried out since 1994 at HIMAC (Heavy Ion Medical Accelerator in Chiba) in NIRS (National Institute of Radiological Sciences). Now, many types of tumors can be treated with carbon beam with excellent local controls of the tumors. Stimulated with good clinical results, requirement of the dedicated compact facility for carbon beam radio-therapy is increased. To realize this requirement, design study of the facility and the R&D's of the key components in this design are promoted by NIRS. According successful results of these activities, the dedicated compact facility will be realized in Gunma University. In this facility, the established irradiation method is expected to use, which is passive irradiation method with wobbler magnets and ridge filter. In this presentation, above R&D's will be presented together with clinical results and basic research activities at HIMAC.

  7. A large-cavity zeolite with wide pore windows and potential as an oil refining catalyst.

    PubMed

    Corma, Avelino; Díaz-Cabañas, María J; Martínez-Triguero, Joaquín; Rey, Fernando; Rius, Jordi

    2002-08-01

    Crude oil is an important feedstock for the petrochemical industry and the dominant energy source driving the world economy, but known oil reserves will cover demand for no more than 50 years at the current rate of consumption. This situation calls for more efficient strategies for converting crude oil into fuel and petrochemical products. At present, more than 40% of oil conversion is achieved using catalysts based on faujasite; this zeolite requires extensive post-synthesis treatment to produce an ultrastable form, and has a large cavity accessible through four 0.74-nm-wide windows and thus limits the access of oil molecules to the catalytically active sites. The use of zeolites with better accessibility to their active sites should result in improved catalyst efficiency. To date, two zeolites with effective pore diameters exceeding that of faujasite have been reported, but their one-dimensional pore topology excludes use in oil refining. Similarly, zeolites with large pores and a three-dimensional pore topology have been reported, but in all these materials the pore openings are smaller than in faujasite. Here we report the synthesis of ITQ-21, a zeolite with a three-dimensional pore network containing 1.18-nm-wide cavities, each of which is accessible through six circular and 0.74-nm-wide windows. As expected for a zeolite with this structure, ITQ-21 exhibits high catalytic activity and selectivity for valuable products in preliminary oil refining tests. PMID:12152074

  8. 40 CFR 60.1820 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... activated carbon? 60.1820 Section 60.1820 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet three requirements: (a) Select a carbon injection system...

  9. Nitrogen-Containing Carbon Nanotube Synthesized from Polymelem and Activated Carbon Derived from Polymer Blend

    NASA Astrophysics Data System (ADS)

    Qin, Nan

    Polymelem possesses a polymeric structure of heptazine (C6N 7) rings connected by amine bridges and our study has demonstrated that it is a promising precursor for the synthesis of nitrogen-containing carbon materials. Nitrogen-containing carbon nanotube (NCNT) was produced by pyrolyzing polymelem as a dual source of carbon and nitrogen with Raney nickel in a high pressure stainless steel cell. Activated carbon was produced from poly(ether ether ketone)/poly(ether imide) (PEEK/PEI blend) and incorporated with polymelem to enhance the hydrogen adsorption. Polymelem was successfully synthesized by pyrolyzing melamine at 450--650 °C and its structure was elucidated by 13C solid state NMR, FTIR, and XRD. The molecular weight determined by a novel LDI MS equipped with a LIFT mode illuminated that polymelem has both linear and cyclic connectivity with a degree of polymerization of 2--5 depending on the synthesis temperature. The decomposition products of polymelem were determined to be cyanoamide, dicyanoamide, and tricyanoamine. Tricyanoamine is the smallest carbon nitride molecule and has been experimentally confirmed for the first time in this study. When polymelem was decomposed in the presence of Raney nickel, homogenous NCNT with nitrogen content of ˜ 4--19 atom% was produced. A mechanism based on a detail analysis of the TEM images at different growth stages proposed that the NCNT propagated via a tip-growth mechanism originating at the nano-domains within the Raney nickel, and was accompanied with the aggregation of the nickel catalysts. Such NCNT exhibited a cup-stack wall structure paired with a compartmental feature. The nitrogen content, tube diameter and wall thickness greatly depended on synthesis conditions. The activated carbon derived from PEEK/PEI blend demonstrated a surface area up to ˜3000 m2/g, and average pore size of < 20 A. Such activated carbon exhibited a hydrogen storage capacity of up to 6.47 wt% at 40 bar, 77 K. The activated carbon has

  10. Synthesis of ‘unfeasible’ zeolites

    NASA Astrophysics Data System (ADS)

    Mazur, Michal; Wheatley, Paul S.; Navarro, Marta; Roth, Wieslaw J.; Položij, Miroslav; Mayoral, Alvaro; Eliášová, Pavla; Nachtigall, Petr; Čejka, Jiří; Morris, Russell E.

    2016-01-01

    Zeolites are porous aluminosilicate materials that have found applications in many different technologies. However, although simulations suggest that there are millions of possible zeolite topologies, only a little over 200 zeolite frameworks of all compositions are currently known, of which about 50 are pure silica materials. This is known as the zeolite conundrum—why have so few of all the possible structures been made? Several criteria have been formulated to explain why most zeolites are unfeasible synthesis targets. Here we demonstrate the synthesis of two such ‘unfeasible’ zeolites, IPC-9 and IPC-10, through the assembly-disassembly-organization-reassembly mechanism. These new high-silica zeolites have rare characteristics, such as windows that comprise odd-membered rings. Their synthesis opens up the possibility of preparing other zeolites that have not been accessible by traditional solvothermal synthetic methods. We envisage that these findings may lead to a step change in the number and types of zeolites available for future applications.

  11. Asphalt-derived high surface area activated porous carbons for carbon dioxide capture.

    PubMed

    Jalilov, Almaz S; Ruan, Gedeng; Hwang, Chih-Chau; Schipper, Desmond E; Tour, Josiah J; Li, Yilun; Fei, Huilong; Samuel, Errol L G; Tour, James M

    2015-01-21

    Research activity toward the development of new sorbents for carbon dioxide (CO2) capture have been increasing quickly. Despite the variety of existing materials with high surface areas and high CO2 uptake performances, the cost of the materials remains a dominant factor in slowing their industrial applications. Here we report preparation and CO2 uptake performance of microporous carbon materials synthesized from asphalt, a very inexpensive carbon source. Carbonization of asphalt with potassium hydroxide (KOH) at high temperatures (>600 °C) yields porous carbon materials (A-PC) with high surface areas of up to 2780 m(2) g(-1) and high CO2 uptake performance of 21 mmol g(-1) or 93 wt % at 30 bar and 25 °C. Furthermore, nitrogen doping and reduction with hydrogen yields active N-doped materials (A-NPC and A-rNPC) containing up to 9.3% nitrogen, making them nucleophilic porous carbons with further increase in the Brunauer-Emmett-Teller (BET) surface areas up to 2860 m(2) g(-1) for A-NPC and CO2 uptake to 26 mmol g(-1) or 114 wt % at 30 bar and 25 °C for A-rNPC. This is the highest reported CO2 uptake among the family of the activated porous carbonaceous materials. Thus, the porous carbon materials from asphalt have excellent properties for reversibly capturing CO2 at the well-head during the extraction of natural gas, a naturally occurring high pressure source of CO2. Through a pressure swing sorption process, when the asphalt-derived material is returned to 1 bar, the CO2 is released, thereby rendering a reversible capture medium that is highly efficient yet very inexpensive. PMID:25531980

  12. Activation and micropore structure of carbon-fiber composites

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.

    1997-12-01

    Rigid, high surface area activated carbon fiber composites have been produced with high permeabilities for environmental applications in gas and water purification. The project involves a collaboration between the Oak Ridge National Laboratory (ORNL) and the Center for Applied Energy Research (CAER), University of Kentucky. The main focus of recent work has been to find a satisfactory means to uniformly activate large samples of carbon fiber composites to produce controlled pore structures. Processes have been developed using activation in steam and CO{sub 2}, and a less conventional method involving oxygen chemisorption and subsequent heat treatment. Another objective has been to explore applications for the activated composites in environmental applications related to fossil energy production.

  13. CONSIDERATIONS IN GRANULAR ACTIVATED CARBON TREATMENT OF COMBINED INDUSTRIAL WASTEWATERS

    EPA Science Inventory

    The objective of this project was to examine the use of activated carbon in reducing the content of biologically resistant organic compounds in a combined industrial wastewater treatment system. The invvestigation was conducted in two stages: (1) characterize organic priority pol...

  14. ACTIVATED CARBON TREATMENT OF INDUSTRIAL WASTEWATERS: SELECTED TECHNICAL PAPERS

    EPA Science Inventory

    Because of the tremendous interest in the organic constituent removal by activated carbon, the two industrial categories displaying the most interest are the petroleum refining and petrochemical industries. EPA's Office of Research and Development has co-sponsored two technical s...

  15. Acoustical Evaluation of Carbonized and Activated Cotton Nonwovens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An activated carbon fiber nonwoven (ACF) was manufactured from cotton nonowoven fabric. For the ACF acoustical application, a nonwoven composite of ACF with cotton nonwoven as a base layer was developed. Also produced were the composites of the cotton nonwoven base layer with a layer of glass fiber ...

  16. Overview of EPA activities and research related to black carbon

    EPA Science Inventory

    The purpose of this international presentation is to give an overview of EPA activities related to black carbon (BC). This overview includes some summary information on how EPA defines BC, current knowledge on United States emissions and forecasted emission reductions, and ongoin...

  17. Decolorization / deodorization of zein via activated carbons and molecular sieves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective is to evaluate a series of granular media consisting of activated carbons and molecular sieves in a batch process for the purpose of clarifying and removal of color and odor components from yellow zein dispersed in an aqueous alcohol medium. The major contributors of yellow zein is du...

  18. MICROBIOLOGICAL ALTERATIONS IN DISTRIBUTED WATER TREATED WITH GRANULAR ACTIVATED CARBON

    EPA Science Inventory

    The goal of this project was to examine the effect of granular activated carbon (GAC) treatment on the microbiological characteristics of potable water in distribution systems. Data was collected from both field and pilot plant studies. Field monitoring studies from two water tre...

  19. Activated carbon injection - a mercury control success story

    SciTech Connect

    2008-07-01

    Almost 100 full-scale activated carbon injection (ACI) systems have been ordered by US electric utilities. These systems have the potential to remove over 90% of the mercury in flue, at a cost below $10,000 per pound of mercury removal. Field trials of ACI systems arm outlined. 1 fig.

  20. Preparation and characterization of activated carbon from demineralized tyre char

    NASA Astrophysics Data System (ADS)

    Manocha, S.; Prasad, Guddu R.; Joshi, Parth.; Zala, Ranjitsingh S.; Gokhale, Siddharth S.; Manocha, L. M.

    2013-06-01

    Activated carbon is the most adsorbing material for industrial waste water treatment. For wider applications, the main consideration is to manufacture activated carbon from low cost precursors, which are easily available and cost effective. One such source is scrap tyres. Recently much effort has been devoted to the thermal degradation of tyres into gaseous and liquid hydrocarbons and solid char residue, all of which have the potential to be processed into valuable products. As for solid residue, char can be used either as low-grade reinforcing filler or as activated carbon. The product recovered by a typical pyrolysis of tyres are usually, 33-38 wt% pyrolytic char, 38-55 wt% oil and 10-30 wt% solid fractions. In the present work activated carbon was prepared from pyrolyzed tyre char (PC). Demineralization involves the dissolution of metal into acids i.e. HCl, HNO3 and H2SO4 and in base i.e. NaOH. Different concentration of acid and base were used. Sodium hydroxide showed maximum amount of metal oxide removal. Further the concentration of sodium hydroxide was varied from 1N to 6N. As the concentration of acid are increased demineralization increases. 6N Sodium hydroxide is found to be more effective demineralising agent of tyre char.

  1. Morphosynthesis of cubic silver cages on monolithic activated carbon.

    PubMed

    Wang, Fei; Zhao, Hong; Lai, Yijian; Liu, Siyu; Zhao, Binyuan; Ning, Yuesheng; Hu, Xiaobin

    2013-11-14

    Cubic silver cages were prepared on monolithic activated carbon (MAC) pre-absorbed with Cl(-), SO4(2-), or PO4(3-) anions. Silver insoluble salts served as templates for the morphosynthesis of silver cages. The silver ions were reduced by reductive functional groups on MAC micropores through a galvanic cell reaction mechanism. PMID:24080952

  2. Ammonia-Activated Mesoporous Carbon Membranes for Gas Separations

    SciTech Connect

    Mahurin, Shannon Mark; Lee, Jeseung; Wang, Xiqing; Dai, Sheng

    2011-01-01

    Porous carbon membranes, which generally show improved chemical and thermal stability compared to polymer membranes, have been used in gas separations for many years. In this work, we show that the post-synthesis ammonia treatment of porous carbon at elevated temperature can improve the permeance and selectivity of these membranes for the separation of carbon dioxide and hydrocarbons from permanent gases. Hierarchically structured porous carbon membranes were exposed to ammonia gas at temperatures ranging from 850 C to 950 C for up to 10 min and the N{sub 2}, CO{sub 2}, and C{sub 3}H{sub 6} permeances were measured for these different membranes. Higher treatment temperatures and longer exposure times resulted in higher gas permeance values. In addition, CO{sub 2}/N{sub 2} and C{sub 3}H{sub 6}/N{sub 2} selectivities increased by a factor of 2 as the treatment temperature and time increased up to a temperature and time of 900 C, 10 min. Higher temperatures showed increased permeance but decreased selectivity indicating excess pore activation. Nitrogen adsorption measurements show that the ammonia treatment increased the porosity of the membrane while elemental analysis revealed the presence of nitrogen-containing surface functionalities in the treated carbon membranes. Thus, ammonia treatment at high temperature provides a controlled method to introduce both added microporosity and surface functionality to enhance gas separations performance of porous carbon membranes.

  3. Fabrication and evaluation of novel zeolite membranes to control the neoplastic activity and anti-tumoral drug treatments in human breast cancer cells. Part 1: Synthesis and characterization of Pure Zeolite Membranes and Mixed Matrix Membranes for adhesion and growth of cancer cells.

    PubMed

    Tavolaro, Palmira; Martino, Guglielmo; Andò, Sebastiano; Tavolaro, Adalgisa

    2016-12-01

    Novel pure and hybrid zeolite membranes were prepared with appropriate different physicochemical characteristics such as frameworks, hydrophilicity, crystal size, chemical composition, acid-base properties (Point of Zero Charge, PZC) and surface morphology and used in inorganic cell/scaffold constructs. Because the control of cell interactions, as the adhesion, proliferation, remodelling and mobility, is important for differentiation and progression of tumors, this work focused on response of cancer cells adhered and grown on synthesized zeolite surfaces in order to study the influence of these scaffolds in controlled conditions. We have selected the MCF-7 and MDA-MB-231 human breast cancer cell line as model tumor cell lines. This study showed that all the zeolite membranes synthesized are excellent scaffolds because they are very selective materials to support the adhesion and growth of neoplastic cells. All zeolite scaffolds were characterized by FESEM, FTIR ATR, XRD, AFM, PZC and contact angle analyses. Cell adhesion, viability and morphology were measured by count, MTT assay and FESEM microphotography analysis, at various incubation times. PMID:27612784

  4. Highly mesoporous single-crystalline zeolite beta synthesized using a nonsurfactant cationic polymer as a dual-function template.

    PubMed

    Zhu, Jie; Zhu, Yihan; Zhu, Liangkui; Rigutto, Marcello; van der Made, Alexander; Yang, Chengguang; Pan, Shuxiang; Wang, Liang; Zhu, Longfeng; Jin, Yinying; Sun, Qi; Wu, Qinming; Meng, Xiangju; Zhang, Daliang; Han, Yu; Li, Jixue; Chu, Yueying; Zheng, Anmin; Qiu, Shilun; Zheng, Xiaoming; Xiao, Feng-Shou

    2014-02-12

    Mesoporous zeolites are useful solid catalysts for conversion of bulky molecules because they offer fast mass transfer along with size and shape selectivity. We report here the successful synthesis of mesoporous aluminosilicate zeolite Beta from a commercial cationic polymer that acts as a dual-function template to generate zeolitic micropores and mesopores simultaneously. This is the first demonstration of a single nonsurfactant polymer acting as such a template. Using high-resolution electron microscopy and tomography, we discovered that the resulting material (Beta-MS) has abundant and highly interconnected mesopores. More importantly, we demonstrated using a three-dimensional electron diffraction technique that each Beta-MS particle is a single crystal, whereas most previously reported mesoporous zeolites are comprised of nanosized zeolitic grains with random orientations. The use of nonsurfactant templates is essential to gaining single-crystalline mesoporous zeolites. The single-crystalline nature endows Beta-MS with better hydrothermal stability compared with surfactant-derived mesoporous zeolite Beta. Beta-MS also exhibited remarkably higher catalytic activity than did conventional zeolite Beta in acid-catalyzed reactions involving large molecules. PMID:24450997

  5. Determining water content in activated carbon for double-layer capacitor electrodes

    NASA Astrophysics Data System (ADS)

    Egashira, Minato; Izumi, Takuma; Yoshimoto, Nobuko; Morita, Masayuki

    2016-09-01

    Karl-Fisher titration is used to estimate water contents in activated carbon and the distribution of impurity-level water in an activated carbon-solvent system. Normalization of the water content of activated carbon is attempted using vacuum drying after immersion in water was controlled. Although vacuum drying at 473 K and 24 h can remove large amounts of water, a substantial amount of water remains in the activated carbon. The water release to propylene carbonate is less than that to acetonitrile. The degradation of capacitor cell capacitance for activated carbon with some amount of water differs according to the electrolyte solvent type: acetonitrile promotes greater degradation than propylene carbonate does.

  6. Zeolites Remove Sulfur From Fuels

    NASA Technical Reports Server (NTRS)

    Voecks, Gerald E.; Sharma, Pramod K.

    1991-01-01

    Zeolites remove substantial amounts of sulfur compounds from diesel fuel under relatively mild conditions - atmospheric pressure below 300 degrees C. Extracts up to 60 percent of sulfur content of high-sulfur fuel. Applicable to petroleum refineries, natural-gas processors, electric powerplants, and chemical-processing plants. Method simpler and uses considerably lower pressure than current industrial method, hydro-desulfurization. Yields cleaner emissions from combustion of petroleum fuels, and protects catalysts from poisoning by sulfur.

  7. Clinoptilolite zeolitized tuff from Central Alborz Range, North Iran

    NASA Astrophysics Data System (ADS)

    Taghipour, Batoul

    2010-05-01

    Zeolites are hydrated alumino-silicates of the alkaline and alkaline earth cations, principally sodium, potassium, calcium, and magnesium (Iijima 1980; Hay 1981). Zeolites occur principally in unmetamorphosed sedimentary rocks and are particularly widespread in volcani-clastic strata (Hay, 1978). Clinoptilolite is a natural zeolite of the heulandite group with the simplified formula of (Na, K)6 Si30 Al6 O72 .nH2. It is the most common natural zeolite found mainly in sedimentary rocks of volcanic origin. Alborz zone is one of the important geological divisions in Iran. This zone is restricted to Kopeh dagh zone in North & Central Iranian zone in South and is a region of active deformation within the broad Arabian-Eurasia collision zone (Allen et al. 2003). The zeolitized green tuff belt from Central Alborz which introduce here are made of volcanoclastic sequence of Karaj Formation. This belt is about 40 km long along Alborz Range and is Eocene in age. Zeolites and associated minerals of this altered vitric tuff studied. Zeolitization took place in some beds of Karaj Formations, with average range of 3 to 300 meters thickness. There are several gypsum lenses which interbed with a widespread green tuff succession in the studied area. On the basis of chemical composition these tuffs are in the range of acid to intermediate volcanic rocks. Also magmatic affinity is calc-alkaline and geological setting of the area belongs to volcanic arc granitoid. Petrographic data has shown that various shape and size of shard glass are the main component of tuffs. Based on the field studies, detail microscopy, XRD and electron microprobe analysis (EMPA), the following main minerals are determined: Clinoptilolite+montmorillonite+crystobalite. Clinoptilolite and smectite are predominant minerals in all altered samples. Concerning the Si/Al ratio of 40 point analyses of glass shards the Alborz tuff has clinoptilolite composition. Otherwise the chemical composition of altered shard glass

  8. PERFORMANCE OF ACTIVATED SLUDGE-POWDERED ACTIVATED CARBON-WET AIR REGENERATION SYSTEMS

    EPA Science Inventory

    The investigation summarized in this report was undertaken to evaluate the performance of powdered activated carbon (PAC) technology used in conjuntion with wet air regeneration (WAR) at municipal wastewater treatment plants. xcessive ash concentrations accumulated in the mixed l...

  9. PERFORMANCE OF ACTIVATED SLUDGE-POWDERED ACTIVATED CARBON-WET AIR REGENERATION SYSTEMS

    EPA Science Inventory

    The investigation summarized in the report was undertaken to evaluate the performance of powdered activated carbon (PAC) technology used in conjunction with wet air regeneration (WAR) at municipal wastewater treatment plants. Excessive ash concentrations accumulated in the mixed ...

  10. Zeolite-like liquid crystals

    PubMed Central

    Poppe, Silvio; Lehmann, Anne; Scholte, Alexander; Prehm, Marko; Zeng, Xiangbing; Ungar, Goran; Tschierske, Carsten

    2015-01-01

    Zeolites represent inorganic solid-state materials with porous structures of fascinating complexity. Recently, significant progress was made by reticular synthesis of related organic solid-state materials, such as metal-organic or covalent organic frameworks. Herein we go a step further and report the first example of a fluid honeycomb mimicking a zeolitic framework. In this unique self-assembled liquid crystalline structure, transverse-lying π-conjugated rod-like molecules form pentagonal channels, encircling larger octagonal channels, a structural motif also found in some zeolites. Additional bundles of coaxial molecules penetrate the centres of the larger channels, unreachable by chains attached to the honeycomb framework. This creates a unique fluid hybrid structure combining positive and negative anisotropies, providing the potential for tuning the directionality of anisotropic optical, electrical and magnetic properties. This work also demonstrates a new approach to complex soft-matter self-assembly, by using frustration between space filling and the entropic penalty of chain extension. PMID:26486751

  11. Zeolite-like liquid crystals

    NASA Astrophysics Data System (ADS)

    Poppe, Silvio; Lehmann, Anne; Scholte, Alexander; Prehm, Marko; Zeng, Xiangbing; Ungar, Goran; Tschierske, Carsten

    2015-10-01

    Zeolites represent inorganic solid-state materials with porous structures of fascinating complexity. Recently, significant progress was made by reticular synthesis of related organic solid-state materials, such as metal-organic or covalent organic frameworks. Herein we go a step further and report the first example of a fluid honeycomb mimicking a zeolitic framework. In this unique self-assembled liquid crystalline structure, transverse-lying π-conjugated rod-like molecules form pentagonal channels, encircling larger octagonal channels, a structural motif also found in some zeolites. Additional bundles of coaxial molecules penetrate the centres of the larger channels, unreachable by chains attached to the honeycomb framework. This creates a unique fluid hybrid structure combining positive and negative anisotropies, providing the potential for tuning the directionality of anisotropic optical, electrical and magnetic properties. This work also demonstrates a new approach to complex soft-matter self-assembly, by using frustration between space filling and the entropic penalty of chain extension.

  12. Zeolite-like liquid crystals.

    PubMed

    Poppe, Silvio; Lehmann, Anne; Scholte, Alexander; Prehm, Marko; Zeng, Xiangbing; Ungar, Goran; Tschierske, Carsten

    2015-01-01

    Zeolites represent inorganic solid-state materials with porous structures of fascinating complexity. Recently, significant progress was made by reticular synthesis of related organic solid-state materials, such as metal-organic or covalent organic frameworks. Herein we go a step further and report the first example of a fluid honeycomb mimicking a zeolitic framework. In this unique self-assembled liquid crystalline structure, transverse-lying π-conjugated rod-like molecules form pentagonal channels, encircling larger octagonal channels, a structural motif also found in some zeolites. Additional bundles of coaxial molecules penetrate the centres of the larger channels, unreachable by chains attached to the honeycomb framework. This creates a unique fluid hybrid structure combining positive and negative anisotropies, providing the potential for tuning the directionality of anisotropic optical, electrical and magnetic properties. This work also demonstrates a new approach to complex soft-matter self-assembly, by using frustration between space filling and the entropic penalty of chain extension. PMID:26486751

  13. Waste polyvinylchloride derived pitch as a precursor to develop carbon fibers and activated carbon fibers.

    PubMed

    Qiao, W M; Yoon, S H; Mochida, I; Yang, J H

    2007-01-01

    Polyvinylchloride (PVC) was successfully recycled through the solvent extraction from waste pipe with an extraction yield of ca. 86%. The extracted PVC was pyrolyzed by a two-stage process (260 and 410 degrees C) to obtain free-chlorine PVC based pitch through an effective removal of chlorine from PVC during the heat-treatment. As-prepared pitch (softening point: 220 degrees C) was spun, stabilized, carbonized into carbon fibers (CFs), and further activated into activated carbon fibers (ACFs) in a flow of CO2. As-prepared CFs show comparable mechanical properties to commercial CFs, whose maximum tensile strength and modulus are 862 MPa and 62 GPa, respectively. The resultant ACFs exhibit a high surface area of 1200 m2/g, narrow pore size distribution and a low oxygen content of 3%. The study provides an effective insight to recycle PVC from waste PVC and develop a carbon precursor for high performance carbon materials such as CFs and ACFs. PMID:17157493

  14. Noble gas adsorption in two-dimensional zeolites: a combined experimental and density functional theory study

    NASA Astrophysics Data System (ADS)

    Wang, Mengen; Zhong, Jianqiang; Boscoboinik, Jorge Anibal; Lu, Deyu

    Zeolites are important industrial catalysts with porous three-dimensional structures. The catalytically active sites are located inside the pores, thus rendering them inaccessible for surface science measurements. We synthesized a two-dimensional (2D) zeolite model system, consisting of an (alumino)silicate bilayer weakly bound to a Ru (0001) surface. The 2D zeolite is suitable for surface science studies; it allows a detailed characterization of the atomic structure of the active site and interrogation of the model system during the catalytic reaction. As an initial step, we use Ar adsorption to obtain a better understanding of the atomic structure of the 2D zeolite. In addition, atomic level studies of rare gas adsorption and separation by zeolite are important for its potential application in nuclear waste sequestration. Experimental studies found that Ar atoms can be trapped inside the 2D-zeolite, raising an interesting question on whether Ar atoms are trapped inside the hexagonal prism nano-cages or at the interface between the (alumino)silicate bilayer and Ru(0001), or both. DFT calculations using van der Waals density functionals were carried out to determine the preferred Ar adsorption sites and the corresponding adsorption energies. This research used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704.

  15. Modeling trapping mechanism for PCB adsorption on activated carbon

    NASA Astrophysics Data System (ADS)

    Jensen, Bjørnar; Kvamme, Bjørn; Kuznetsova, Tatyana; Oterhals, A.˚ge

    2012-12-01

    The levels of polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran (PCDD/F) and dioxin-like polychlorinated biphenyl (DL-PCB) in fishmeal and fish oil produced for use in feed for salmon is above present European legislation levels in some regions of the world and different decontamination approaches have been proposed [1]. One of these is adsorption on activated carbon. This approach appears to be efficient for adsorption of PCDD/F but less efficient for DL-PCB [2]. Activated carbon consists of slit pores with average sizes of 20 - 50 Ångstroms. One hypothesis [2] for the mechanism of trapping DL-PCB is reduced ability for intramolecular movements of the PCB molecules inside the slit pores. In order to investigate this hypothesis we have used quantum mechanics [3] to characterize two DL-PCB congeners, respectively congener 77 (3,3',4,4'-Tetrachlorobiphenyl) and congener 118 (2,3',4,4',5-Pentachlorobiphenyl) and Triolein (18:1) [4] as a major constituent of the solvent fish oil. A model for activated carbon was constructed using a crystal structure of graphite from the American Mineralogist Crystal Structure Database [5]. The crystal structure used was originally from Wyckoff [6]. A small program had to be written to generate the desired graphite structure as it contains no less than 31232 Carbon atoms. Partial atomic charges were estimated using QM with DFT/B3LYP/6-311+g** and SM6 [7].

  16. Estimates of increased black carbon emissions from electrostatic precipitators during powdered activated carbon injection for mercury emissions control.

    PubMed

    Clack, Herek L

    2012-07-01

    The behavior of mercury sorbents within electrostatic precipitators (ESPs) is not well-understood, despite a decade or more of full-scale testing. Recent laboratory results suggest that powdered activated carbon exhibits somewhat different collection behavior than fly ash in an ESP and particulate filters located at the outlet of ESPs have shown evidence of powdered activated carbon penetration during full-scale tests of sorbent injection for mercury emissions control. The present analysis considers a range of assumed differential ESP collection efficiencies for powdered activated carbon as compared to fly ash. Estimated emission rates of submicrometer powdered activated carbon are compared to estimated emission rates of particulate carbon on submicrometer fly ash, each corresponding to its respective collection efficiency. To the extent that any emitted powdered activated carbon exhibits size and optical characteristics similar to black carbon, such emissions could effectively constitute an increase in black carbon emissions from coal-based stationary power generation. The results reveal that even for the low injection rates associated with chemically impregnated carbons, submicrometer particulate carbon emissions can easily double if the submicrometer fraction of the native fly ash has a low carbon content. Increasing sorbent injection rates, larger collection efficiency differentials as compared to fly ash, and decreasing sorbent particle size all lead to increases in the estimated submicrometer particulate carbon emissions. PMID:22663136

  17. Catalytic pyrolysis using UZM-39 aluminosilicate zeolite

    SciTech Connect

    Nicholas, Christopher P; Boldingh, Edwin P

    2014-10-07

    A new family of coherently grown composites of TUN and IMF zeotypes has been synthesized and shown to be effective catalysts for catalytic pyrolysis of biomass. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.n+R.sub.rQ.sub.qAl.sub.1-xE.sub.xSi.sub.yO.s- ub.z where M represents zinc or a metal or metals from Group 1, Group 2, Group 3 or the lanthanide series of the periodic table, R is an A,.OMEGA.-dihalosubstituted paraffin such as 1,4-dibromobutane, Q is a neutral amine containing 5 or fewer carbon atoms such as 1-methylpyrrolidine and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-39 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  18. Catalytic pyrolysis using UZM-39 aluminosilicate zeolite

    SciTech Connect

    Nicholas, Christpher P; Boldingh, Edwin P

    2013-12-17

    A new family of coherently grown composites of TUN and IMF zeotypes has been synthesized and show to be effective catalysts for catalytic pyrolysis of biomass. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.n+R.sub.rQ.sub.qAl.sub1-xE.sub.xSi.sub.yO.s- ub.z where M represents zinc or a metal or metals from Group 1, Group 2, Group 3 or the lanthanide series of the periodic table, R is an A,.OMEGA.-dihalosubstituted paraffin such as 1,4-dibromobutane, Q is a neutral amine containing 5 or fewer carbon atoms such as 1-methylpyrrolidine and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-39 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hyrdocarbons into hydrocarbons removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  19. Formation of continuous activated carbon fibers for barrier fabrics

    NASA Astrophysics Data System (ADS)

    Liang, Ying

    1997-08-01

    Commercial protective suits made of active carbon granules or nonwoven fabrics are heavy, have low moisture vapor transport rate, and are uncomfortable. Inherent problems due to construction of barrier fabrics lead to severe heat stress when worn for even short time in warm environments. One proposed method to eliminate these problems is to facilitate the construction of a fabric made of continuous activated carbon fibers (CACF). This study is directed toward investigating the possibility of developing CAFC from two precursors: aramid and fibrillated PAN fiber. It was shown in this study that Kevlar-29 fibers could be quickly carbonized and activated to CACF with high adsorptivity and relatively low weight loss. CACF with high surface area (>500 msp2/g) and reasonable tenacity (≈1g/denier) were successfully prepared from Kevlar fibers through a three-step process: pretreatment, carbonization, and activation. X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and thermal analysis were conducted to understand the evolution of physical and chemical properties during pretreatment. The influence of temperature, heating rate, and pyrolysis environment on the thermal behavior was determined by DSC and TGA/DTA and used as an indicator for optimizing the pyrolysis conditions. Surface analysis by nitrogen isotherms indicated that the resultant fibers had micropores and mesopores on the surface of CACF. This was also inferred by studies on the surface morphology through Scanning Electron Microscopy (SEM) and Scanning Tunneling Microscopy (STM). An investigation of the surface chemical structure by X-ray photoelectron spectroscopy (XPS) before and after activation and elemental analysis confirmed that adsorption of Kevlar based CACF mainly arises due to the physisorption instead of chemisorption. A multistep stabilization along with carbonization and activation was used to prepare active carbon fiber from fibrillated PAN fiber. The resultant fiber retained

  20. Irreversible adsorption of phenolic compounds by activated carbons

    SciTech Connect

    Grant, T.M.; King, C.J.

    1988-12-01

    Studies were undertaken to determine the reasons why phenolic sorbates can be difficult to remove and recover from activated carbons. The chemical properties of the sorbate and the adsorbent surface, and the influences of changes in the adsorption and desorption conditions were investigated. Comparison of isotherms established after different contact times or at different temperatures indicated that phenolic compounds react on carbon surfaces. The reaction rate is a strong function of temperature. Regeneration of carbons by leaching with acetone recovered at least as much phenol as did regeneration with other solvents or with displacers. The physiochemical properties of adsorbents influences irreversible uptakes. Sorbates differed markedly in their tendencies to undergo irreversible adsorption. 64 refs., 47 figs., 32 tabs.

  1. Sorption of cobalt on activated carbons from aqueous solutions

    SciTech Connect

    Paajanen, A.; Lehto, J.; Santapakka, T.; Morneau, J.P.

    1997-01-01

    The efficiencies of 15 commercially available activated carbons were tested for the separation of trace cobalt ({sup 60}Co) in buffer solutions at pH 5.0, 6.7, and 9.1. On the basis of the results four carbon products, Diahope-006, Eurocarb TN5, Hydraffin DG47, and Norit ROW Supra, were selected for further study. These carbons represented varying (low, medium and high) cobalt removal efficiencies and were prepared of three typical raw materials: peat, coconut shell, or coal. Study was made of the effects on sorption efficiencies of factors of interest in metal/radionuclide-bearing waste effluents. These factors were pH, sodium ions, borate, and citrate.

  2. Waste management activities and carbon emissions in Africa

    SciTech Connect

    Couth, R.; Trois, C.

    2011-01-15

    This paper summarizes research into waste management activities and carbon emissions from territories in sub-Saharan Africa with the main objective of quantifying emission reductions (ERs) that can be gained through viable improvements to waste management in Africa. It demonstrates that data on waste and carbon emissions is poor and generally inadequate for prediction models. The paper shows that the amount of waste produced and its composition are linked to national Gross Domestic Product (GDP). Waste production per person is around half that in developed countries with a mean around 230 kg/hd/yr. Sub-Saharan territories produce waste with a biogenic carbon content of around 56% (+/-25%), which is approximately 40% greater than developed countries. This waste is disposed in uncontrolled dumps that produce large amounts of methane gas. Greenhouse gas (GHG) emissions from waste will rise with increasing urbanization and can only be controlled through funding mechanisms from developed countries.

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

    SciTech Connect

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

    1999-11-01

    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.

  4. Sorption Behaviour of Armenian Natural Zeolites

    SciTech Connect

    Keheyan, Y.; Khachatryan, S.; Christidis, G.; Moraetis, D.; Gevorkyan, R.; Sarkisyan, H.; Yeritsyan, H.; Nikoghosyan, S.; Sahakyan, A.; Kekelidze, N.; Akhalbedashvili, L.

    2005-07-15

    The sorptive behaviour of radioactive waste on Armenian zeolites, natural, irradiated, chemically treated and heated at high temperatures was studied and their capacity for the separation and enrichment of radionuclides was evaluated.The influence of temperature, acidity, basicity, specific activity, electron and gamma irradiation on sorption have been studied. The chemical analysis of exchanged samples was carried out and the cation exchange capacity was determined. Absorption properties of mono-cationic forms of different clinoptilolite samples were studied depending on type of guest cation and contact time.By means of model experiments the laboratory plant for absorption of metal cations from solutions in dynamic regime was designed and developed. This plant was used for experiments of radioactive waste removal from the Armenian nuclear reactor.

  5. Characterization and metal sorptive properties of oxidized active carbon.

    PubMed

    Strelko, Vladimir; Malik, Danish J

    2002-06-01

    A commercial activated carbon Chemviron F 400 has been oxidized using nitric acid in order to introduce a variety of acidic surface functional groups. Both unoxidized and oxidized carbon samples were characterized using nitrogen porosimetry, elemental analysis, pH titration, Boehm's titration, and electrophoretic mobility measurements. Results show that oxidation treatment reduced surface area and pore volume. However, the carbon surface acquires an acidic character with carboxylic groups being the dominant surface functional groups. The modified sample displays cation-exchange properties over a wide range of pH values and exhibits polyfunctional nature. Both carbon samples were challenged for the removal of transition metals such as copper(II), nickel(II), cobalt(II), zinc(II), and manganese(II). The affinity series Mn2+Zn2+ has been found to coincide with the general stability sequence of metal complexes (the Irving-Williams series). The higher preference displayed by carbons toward copper(II) is a consequence of the fact that copper(II) often forms distorted and more stable octahedral complexes. PMID:16290653

  6. Enhancing capacitive deionization performance of electrospun activated carbon nanofibers by coupling with carbon nanotubes.

    PubMed

    Dong, Qiang; Wang, Gang; Wu, Tingting; Peng, Senpei; Qiu, Jieshan

    2015-05-15

    Capacitive deionization (CDI) is an alternative, effective and environmentally friendly technology for desalination of brackish water. The performance of the CDI device is highly determined by the electrode materials. In this paper, a composite of carbon nanotubes (CNTs) embedded in activated carbon nanofiber (ACF) was prepared by a direct co-electrospinning way and subsequent CO2 activation. The introduction of CNTs can greatly improve the conductivity while the CO2-mediated activation can render the final product with high porosity. As such, the hybrid structure can provide an excellent storage space and pathways for ion adsorption and conduction. When evaluated as electrode materials for CDI, the as-prepared CNT/ACF composites with higher electrical conductivity and mesopore ratios exhibited higher electrosorption capacity and good regeneration performance in comparison with the pure ACF. PMID:25595622

  7. Nomex-derived activated carbon fibers as electrode materials in carbon based supercapacitors

    NASA Astrophysics Data System (ADS)

    Leitner, K.; Lerf, A.; Winter, M.; Besenhard, J. O.; Villar-Rodil, S.; Suárez-García, F.; Martínez-Alonso, A.; Tascón, J. M. D.

    Electrochemical characterization has been carried out for electrodes prepared of several activated carbon fiber samples derived from poly (m-phenylene isophthalamide) (Nomex) in an aqueous solution. Depending on the burn-off due to activation the BET surface area of the carbons was in the order of 1300-2800 m 2 g -1, providing an extensive network of micropores. Their capability as active material for supercapacitors was evaluated by using cyclic voltammetry and impedance spectroscopy. Values for the capacitance of 175 F g -1 in sulfuric acid were obtained. Further on, it was observed that the specific capacitance and the performance of the electrode increase significantly with increasing burn-off degree. We believe that this fact can be attributed to the increase of surface area and porosity with increasing burn-off.

  8. Characterization of zeolite structure and fluorocarbon reactivity using solid state NMR and x-ray powder diffraction

    NASA Astrophysics Data System (ADS)

    Ciraolo, Michael Frank

    The research presented in this thesis involves a combination of techniques used to study the structure and interactions zeolites adsorbed with fluorocarbons. This research is specifically aimed at understanding the processes of adsorption, binding, and reactivity of fluorocarbons on cation exchanged faujasite type zeolites. The solid state ion exchange process has also been studied since it is one way to obtain materials with higher exchange levels, which has been shown to effect adsorption and catalytic activity. To improve the understanding of the adsorption and separation processes a time resolved in-situ synchrotron x-ray powder diffraction study has been undertaken. Since faujasite type zeolites have been found to be effective in separating mixtures of HFC-134 (CF2HCF2H) and HFC-134a (CFH2CF3) isomers, the adsorption of these fluorocarbons on NaY have been studied. It has been shown that both the extent of loading and the kinetics of the sorption process in molecular sieves can be followed using this technique. A model for the binding of hydrochlorofluorocarbon (HCFC) 124a (CF 2HCF2Cl) adsorbed on NaX at 100K has been determined using a combination x-ray and neutron powder diffraction and solid state NMR. Using Rietveld refinement of the diffraction data, the HCFC molecule was found localized in the zeolite cavities bound on either end by sodium cations in the SII and SIII' positions. The model is consistent with hydrogen bonding between the proton of the HCFC and the framework oxygen. The NMR results further confirm the model and are consistent with Na-F binding and HCFC-framework interactions. Solid-state MAS NMR, synchrotron X-ray powder diffraction and a mass spectrometer and gas chromatograph catalysis system have been used to study the reactivity of HCFC-124a (CF2HCF2Cl) on NaX, Zn 2+-exchanged NaX (ZnX) and Rb+-exchanged NaX (RbX). We have chosen to study HCFC-124a (CF2HCF2Cl) since HCFC-124a can undergo both dehydrofluorination and dehydrochlorination

  9. Visible emission from Ag+ exchanged SOD zeolites

    NASA Astrophysics Data System (ADS)

    Lin, H.; Imakita, K.; Fujii, M.; Prokof'ev, V. Yu.; Gordina, N. E.; Saïd, B.; Galarneau, A.

    2015-09-01

    Broad visible emissions dominant at green or red have been observed for the thermally-treated Ag+ exchanged SOD zeolites, determined by the Ag+ loading contents and the excitation wavelengths. Contrary to the notable reversible green/red dominant emission evolution in the Ag+ exchanged LTA zeolites upon hydration/dehydration in air (or water vapor)/vacuum, emission spectra of the Ag+ exchanged SOD zeolites are insensitive to the environmental change. This is most probably due to the difficult H2O permeation in SOD zeolites in comparison with LTA zeolites. By combining the environment dependent emission spectra of the Ag+ exchanged LTA and SOD zeolites, we proposed the following emission mechanisms for Ag+ exchanged LTA and SOD zeolites: the green emission is due to the transition from ligand-to-metal (framework O2- --> Ag+) charge transfer state to the ground state and the red emission is due to the transition from the metal-metal (Ag+-Ag+) charge transfer state to the ground state. The insensitive environment dependent emission characteristics of Ag+ exchanged SOD zeolites may have potential applications as robust phosphors.

  10. Production and characterization of activated carbons from cereal grains

    SciTech Connect

    Venkatraman, A.; Walawender, S.P.; Fan, L.T.

    1996-10-01

    The kernels of grain such as corn and hard red winter wheat were subjected to a two-stage pyrolytic process to generate relatively high yields of charcoals. The process involved carbonization of the kernels at low temperatures (250-325{degrees}C) followed by complete devolatilization of the resultant charcoals at around 750{degrees}C. The charcoals were subsequently activated physically with CO{sub 2} at 800{degrees}C to yield activated carbons. The total pore volumes and surface areas of the activated carbons were determined at various degree of activation by physisorption methods. The surface areas from the nitrogen BET method ranged from 500 to 1750 m{sup 2}/g, while the total pore volumes obtained from the volumes at saturation were in the interval from 0.3 to 0.7 cm{sup 3}/g. The fractal nature of the pore interfaces as well as the existence of different types of pores were investigated through small-angle x-ray scattering.

  11. Antibacterial activity of carbon-coated zinc oxide particles.

    PubMed

    Sawai, Jun; Yamamoto, Osamu; Ozkal, Burak; Nakagawa, Zenbe-E

    2007-03-01

    Particles of ZnO coated with carbon (ZnOCC) were prepared and evaluated for their antibacterial activity. ZnO powder and poly(vinyl alcohol) (PVA) (polymerization degree: 2,000-95,000) were mixed at a mass ratio (ZnO/PVA) of 1, and then heated at 500-650 degree C for 3 h under argon gas with a flow rate of 50ml/min. Carbon deposited on the ZnOCC surface was amorphous as revealed by X-ray diffraction studies. The ZnOCC particles maintained their shape in water, even under agitation. The antibacterial activity of ZnOCC powder against Staphylococcus aureus was evaluated quantitatively by measuring the change in the electrical conductivity of the growth medium caused by bacterial metabolism (conductimetric assay). The conductivity curves obtained were analyzed using the growth inhibition kinetic model proposed by Takahashi for calorimetric evaluation, allowing the estimation of the antibacterial efficacy and kinetic parameters of ZnOCC. In a previous study, when ZnO was immobilized on materials, such as activated carbon, the amount of ZnO immobilized was approximately 10-50%, and the antibacterial activity markedly decreased compared to that of the original ZnO. On the other hand, the ZnOCC particles prepared in this study contained approximately 95% ZnO and possessed antibacterial activity similar to that of pure ZnO. The carbon-coating treatment could maintain the antibacterial efficacy of the ZnO and may be useful in the develop-ment of multifunctional antimicrobial materials. PMID:17408004

  12. Adsorption of chlorine dioxide gas on activated carbons.

    PubMed

    Wood, Joseph P; Ryan, Shawn P; Snyder, Emily Gibb; Serre, Shannon D; Touati, Abderrahmane; Clayton, Matthew J

    2010-08-01

    Research and field experience with chlorine dioxide (ClO2) gas to decontaminate structures contaminated with Bacillus anthracis spores and other microorganisms have demonstrated the effectiveness of this sterilant technology. However, because of its hazardous properties, the unreacted ClO2, gas must be contained and captured during fumigation events. Although activated carbon has been used during some decontamination events to capture the ClO2 gas, no data are available to quantify the performance of the activated carbon in terms of adsorption capacity and other sorbent property operational features. Laboratory experiments were conducted to determine and compare the ClO2 adsorption capacities of five different types of activated carbon as a function of the challenge ClO2 concentration. Tests were also conducted to investigate other sorbent properties, including screening tests to determine gaseous species desorbed from the saturated sorbent upon warming (to provide an indication of how immobile the ClO2 gas and related compounds are once captured on the sorbent). In the adsorption tests, ClO2 gas was measured continuously using a photometric-based instrument, and these measurements were verified with a noncontinuous method utilizing wet chemistry analysis. The results show that the simple activated carbons (not impregnated or containing other activated sorbent materials) were the most effective, with maximum adsorption capacities of approximately 110 mg/g. In the desorption tests, there was minimal release of ClO(2) from all sorbents tested, but desorption levels of chlorine (Cl2) gas (detected as chloride) varied, with a maximum release of nearly 15% of the mass of ClO2 adsorbed. PMID:20842929

  13. Production of charcoal and activated carbon at elevated pressure

    SciTech Connect

    Dai, Xiangfeng; Norberg, N.; Antal, M.J. Jr.

    1995-12-31

    With its wide range of properties, charcoal finds many commercial applications for domestic cooking, refining of metals (steel, copper, bronze, nickel, aluminum and electro-manganese), production of chemicals (carbon disulfide, calcium carbide, silicon carbide, sodium cyanide, carbon black, fireworks, gaseous chemicals, absorbents, soil conditioners and pharmaceuticals), as well as production of activated carbon and synthesis gas. In 1991, the world production of charcoal was 22.8 million cubic meters (3.8 million metric tons) as shown in Table 1. Brazil is the world`s largest charcoal producer --- 5.9 million cubic meters or one million metric tons was produced in 1991, most of which is used in steel and iron industry. African countries produced 45% of the world total amount of charcoal, where 86% of the wood-based energy is for domestic use, most of which is inefficiently used. Charcoal is produced commercially in kilns with a 25% to 30% yield by mass on a 7 to 12 day operating cycle. Until recently, the highest yield of good quality charcoal reported in the literature was 38%. In this paper, and ASME code rated experimental system is presented for producing charcoal and activated carbon from biomass.

  14. Synthesis and Antioxidant Activity of Hydroxytyrosol Alkyl-Carbonate Derivatives.

    PubMed

    Fernandez-Pastor, Ignacio; Fernandez-Hernandez, Antonia; Rivas, Francisco; Martinez, Antonio; Garcia-Granados, Andres; Parra, Andres

    2016-07-22

    Three procedures have been investigated for the isolation of tyrosol (1) and hydroxytyrosol (2) from a phenolic extract obtained from the solid residue of olive milling. These three methods, which facilitated the recovery of these phenols, were chemical or enzymatic acetylation, benzylation, and carbomethoxylation, and subsequent carbonylation or acetonation reactions. Several new lipophilic alkyl-carbonate derivatives of hydroxytyrosol have been synthesized, coupling the primary hydroxy group of this phenol, through a carbonate linker, using alcohols with different chain lengths. The antioxidant properties of these lipophilic derivatives have been evaluated by different methods and compared with free hydroxytyrosol (2) and also with the well-known antioxidants BHT and α-tocopherol. Three methods were used for the determination of this antioxidant activity: FRAP and ABTS assays, to test the antioxidant power in hydrophilic media, and the Rancimat test, to evaluate the antioxidant capacity in a lipophilic matrix. These new alkyl-carbonate derivatives of hydroxytyrosol enhanced the antioxidant activity of this natural phenol, with their antioxidant properties also being higher than those of the commercial antioxidants BHT and α-tocopherol. There was no clear influence of the side-chain length on the antioxidant properties of the alkyl-carbonate derivatives of 2, although the best results were achieved mainly by the compounds with a longer chain on the primary hydroxy group of this natural phenolic substance. PMID:27337069

  15. 40 CFR 62.15275 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... activated carbon? 62.15275 Section 62.15275 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet three requirements: (a) Select a carbon injection system...

  16. 40 CFR 62.15275 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... activated carbon? 62.15275 Section 62.15275 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet three requirements: (a) Select a carbon injection system...

  17. 40 CFR 62.15275 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... activated carbon? 62.15275 Section 62.15275 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet three requirements: (a) Select a carbon injection system...

  18. 40 CFR 62.15275 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... activated carbon? 62.15275 Section 62.15275 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet three requirements: (a) Select a carbon injection system...

  19. Influence of natural zeolite and nitrification inhibitor on organics degradation and nitrogen transformation during sludge composting.

    PubMed

    Zhang, Junya; Sui, Qianwen; Li, Kun; Chen, Meixue; Tong, Juan; Qi, Lu; Wei, Yuansong

    2016-01-01

    Sludge composting is one of the most widely used treatments for sewage sludge resource utilization. Natural zeolite and nitrification inhibitor (NI) are widely used during composting and land application for nitrogen conservation, respectively. Three composting reactors (A--the control, B--natural zeolite addition, and C--3,4-dimethylpyrazole phosphate (DMPP) addition) were established to investigate the influence of NI and natural zeolite addition on organics degradation and nitrogen transformation during sludge composting conducted at the lab scale. The results showed that, in comparison with the control, natural zeolite addition accelerated organics degradation and the maturity of sludge compost was higher, while the DMPP addition slowed down the degradation of organic matters. Meanwhile, the nitrogen transformation functional genes including those responses for nitrification (amoA and nxrA) and denitrification (narG, nirS, nirK, and nosZ) were quantified through quantitative PCR (qPCR) to investigate the effects of natural zeolites and DMPP addition on nitrogen transformation. Although no significant difference in the abundance of nitrogen transformation functional genes was observed between treatments, addition of both natural zeolite and DMPP increases the final total nitrogen content by 48.6% and 23.1%, respectively. The ability of natural zeolite for nitrogen conservation was due to the absorption of NH3 by compost, and nitrogen conservation by DMPP was achieved by the source reduction of denitrification. Besides, it was assumed that the addition of natural zeolite and DMPP may affect the activity of these genes instead of the abundance. PMID:26358216

  20. In-situ imaging of reacting single-particle zeolites by non-linear optical microscopy

    NASA Astrophysics Data System (ADS)

    Wrzesinski, Paul J.; Slipchenko, Mikhail N.; Zaman, Taslima A.; Rioux, Robert M.; Gord, James R.; Roy, Sukesh

    2015-03-01

    Zeolite catalysis has been exploited by the petrochemical industry since the 1940's for catalytic cracking reactions of long chain hydrocarbons. The selectivity of zeolites strongly depends on a pore size, which is controlled by the chosen structure-directing agent (SDA) and by the SDA decomposition/removal process. Although zeolites are composed of micron-sized crystals, studies of zeolite materials typically focus on bulk (i.e., ensemble) measurements to elucidate structure-function information or to optimize catalysts and/or process parameters. To examine these phenomena on the microscale, non-linear optical microscopy is used to provide real-time imaging of chemical reactions in zeolites at temperatures exceeding 400°C. The template decomposition mechanism is studied, as elucidation of the mechanism is critical to understanding the relationship between the decomposition chemistry and the nanoscale features of the zeolite (topology, Si/Al ratio, added dopants). Forward stimulated Raman scattering (SRS), forward coherent anti-Stokes Raman scattering (CARS) and epi two-photon fluorescence (TPF) modalities are acquired simultaneously providing video-rate structural and chemical information. A high-temperature cell with gas inlet system is used for the study of reactions under various temperatures and gas environments. Examining the decomposition process with single-particle resolution enables access to ensemble-level and spatially-resolved behavior. Parallel experiments on bulk zeolite powders are conducted to enable comparison of ensemble and single-particle behavior during template decomposition. Our multi-technique approach has high potential for gaining insight into the link between nanoscale structure and catalytic activity and selectivity of zeolitic materials.

  1. Metallo-hydrazone complexes immobilized in zeolite Y: Synthesis, identification and acid violet-1 degradation

    NASA Astrophysics Data System (ADS)

    Ahmed, Ayman H.; Thabet, M. S.

    2011-12-01

    Copper(II), cobalt(II) and nickel(II) complexes of hydrazone ligand (SAPH) derived from salicylaldehyde and phenylhydrazine have been encapsulated in zeolite-Y super cages via ship-in-a-bottle synthesis. Detailed characterization of the intrazeolitic complexes were performed by elemental analysis, spectral (FT-IR, UV-Vis.) studies, magnetic measurements and X-ray diffraction. Furthers, surface texture and thermal analysis (TG, DTG, DTA) have provided further evidence for successful immobilization of the metal complexes inside zeolite Y. Investigation of the stereochemistry of these incorporated chelates pointed out that, SAPH ligand is capable to coordinate with the central metal through the (C dbnd N), phenolic (OH) and (NH) groups forming polynuclear structures. The involvement of zeolite oxygen in coordination was postulated in the hybrid materials. The intrazeolitic copper, cobalt and nickel-SAPH complexes have distorted tetrahedral, octahedral and square-pyramidal configurations, respectively. The zeolite encapsulated complexes are thermally stable up to 800 °C except Cu(II) sample which is thermally stable up to midpoint 428 °C. The assessment of the catalytic activity was performed by the use of the photo-degradation of acid violet-1 dye as a probe reaction in presence of H 2O 2 as an oxidant. Decolorization of acid violet-1 dye was examined under the same conditions whereas the unpromoted zeolite and Cu II, Co II, Ni II-hydrazone complexes supported on zeolite showed 13% and 76%, 53%, 43% color removal, respectively. The results revealed that, the zeolite encapsulated Cu(II) complex generally exhibited better catalytic efficiency (76%) compared with other investigated zeolite encapsulated metal-hydrazone samples.

  2. Activation and micropore structure determination of activated carbon-fiber composites

    SciTech Connect

    Jagtoyen, M.; Derbyshire, F.; Kimber, G.

    1997-09-05

    Rigid, high surface area activated carbon fiber composites have been produced with high permeabilities for environmental applications in gas and water purification. These novel monolithic adsorbents can be produced in single pieces to a given size and shape. The project involves a collaboration between the Oak Ridge National Laboratory (ORNL) and the Center for Applied Energy Research (CAER), University of Kentucky. The carbon fiber composites are produced at the ORNL and activated at the CAER using different methods, with the aims of producing a uniform degree of activation, and of closely controlling pore structure and adsorptive properties. The main focus of the present work has been to find a satisfactory means to uniformly activate large samples of carbon fiber composites and produce controlled pore structures. Several environmental applications have been explored for the activated carbon fiber composites. One of these was to evaluate the activated composites for the separation of CH{sub 4}-CO{sub 2} mixtures, and an apparatus was constructed specifically for this purpose. The composites were further evaluated in the cyclic recovery of volatile organics. The activated carbon fiber composites have also been tested for possible water treatment applications by studying the adsorption of sodium pentachlorophenolate, PCP.

  3. UTILITY OF ZEOLITES IN ARSENIC REMOVAL FROM WATER

    EPA Science Inventory

    Zeolites are well known for their ion exchange and adsorption properties. So far the cation exchanger properties of zeolites have been extensively studied and utilized. The anion exchanger properties of zeolites are less studied. Zeolite Faujasite Y has been used to remove arseni...

  4. Activated carbon from leather shaving wastes and its application in removal of toxic materials.

    PubMed

    Kantarli, Ismail Cem; Yanik, Jale

    2010-07-15

    In this study, utilization of a solid waste as raw material for activated carbon production was investigated. For this purpose, activated carbons were produced from chromium and vegetable tanned leather shaving wastes by physical and chemical activation methods. A detailed analysis of the surface properties of the activated carbons including acidity, total surface area, extent of microporosity and mesoporosity was presented. The activated carbon produced from vegetable tanned leather shaving waste produced has a higher surface area and micropore volume than the activated carbon produced from chromium tanned leather shaving waste. The potential application of activated carbons obtained from vegetable tanned shavings as adsorbent for removal of water pollutants have been checked for phenol, methylene blue, and Cr(VI). Adsorption capacities of activated carbons were found to be comparable to that of activated carbons derived from biomass. PMID:20382474

  5. Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

    DOE PAGESBeta

    Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; Dai, Sheng

    2015-05-11

    Ultrahigh surface area carbons (USACs, e.g., >2000 m2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. This strategy coversmore » various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, andFanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g-1) even at a scan rate of 1000 mV s-1. Thus, a simple and efficient strategy to USACs has been presented.« less

  6. Carbon nanofibers grafted on activated carbon as an electrode in high-power supercapacitors.

    PubMed

    Gryglewicz, Grażyna; Śliwak, Agata; Béguin, François

    2013-08-01

    A hybrid electrode material for high-power supercapacitors was fabricated by grafting carbon nanofibers (CNFs) onto the surface of powdered activated carbon (AC) through catalytic chemical vapor deposition (CCVD). A uniform thin layer of disentangled CNFs with a herringbone structure was deposited on the carbon surface through the decomposition of propane at 450 °C over an AC-supported nickel catalyst. CNF coating was controlled by the reaction time and the nickel content. The superior CNF/AC composite displays excellent electrochemical performance in a 0.5 mol L(-1) solution of K2 SO4 due to its unique structure. At a high scan rate (100 mV s(-1) ) and current loading (20 A g(-1) ), the capacitance values were three- and fourfold higher than those for classical AC/carbon black composites. Owing to this feature, a high energy of 10 Wh kg(-1) was obtained over a wide power range in neutral medium at a voltage of 0.8 V. The significant enhancement of charge propagation is attributed to the presence of herringbone CNFs, which facilitate the diffusion of ions in the electrode and play the role of electronic bridges between AC particles. An in situ coating of AC with short CNFs (below 200 nm) is a very attractive method for producing the next generation of carbon composite materials with a high power performance in supercapacitors working in neutral medium. PMID:23794416

  7. Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

    SciTech Connect

    Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; Dai, Sheng

    2015-05-11

    Ultrahigh surface area carbons (USACs, e.g., >2000 m2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. This strategy covers various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, andFanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g-1) even at a scan rate of 1000 mV s-1. Thus, a simple and efficient strategy to USACs has been presented.

  8. The effect of zeolite treatment by acids on sodium adsorption ratio of coal seam gas water.

    PubMed

    Wang, Xiaoyu; Ozdemir, Orhan; Hampton, Marc A; Nguyen, Anh V; Do, Duong D

    2012-10-15

    Many coal seam gas (CSG) waters contain a sodium ion concentration which is too high relative to calcium and magnesium ions for environment acceptance. Natural zeolites can be used as a cheap and effective method to control sodium adsorption ratio (SAR, which is a measure of the relative preponderance of sodium to calcium and magnesium) due to its high cation exchange capacity. In this study, a natural zeolite from Queensland was examined for its potential to treat CSG water to remove sodium ions to lower SAR and reduce the pH value. The results demonstrate that acid activated zeolite at 30%wt solid ratio can reduce the sodium content from 563.0 to 182.7 ppm; the pH from 8.74 to 6.95; and SAR from 70.3 to 18.5. Based on the results of the batch experiments, the sodium adsorption capacity of the acid-treated zeolite is three times greater than that of the untreated zeolite. Both the untreated and acid-treated zeolite samples were characterized using zeta potential, surface characterization, DTA/TG and particle size distribution in order to explain their adsorption behaviours. PMID:22841594

  9. New insights into alkylammonium-functionalized clinoptilolite and Na-P1 zeolite: Structural and textural features

    NASA Astrophysics Data System (ADS)

    Muir, Barbara; Matusik, Jakub; Bajda, Tomasz

    2016-01-01

    The area of zeolites' application could be expanded by utilizing their surfaces. Zeolites are frequently modified to increase their hydrophobicity and to generate the negative charge of the surface. The main objective of the study was to investigate and compare the features of natural clinoptilolite and synthetic zeolite Na-P1 modified by selected surfactants involving quaternary ammonium salts. The FTIR study indicates that with increasing carbon chain length in the surfactant attached to the zeolites surface the molecules adopt a more disordered structure. FTIR was also used to determine the efficiency of surface modification. Thermal analysis revealed that the presence of surfactant results in additional exothermic effects associated with the breaking of electrostatic bonds between zeolites and surfactants. The mass losses are in line with ECEC and CHN data. The textural study indicates that the synthetic zeolite Na-P1 has better sorption properties than natural clinoptilolite. The modification process always reduces the SBET and porosity of the material. With an increasing carbon chain length of surfactants all the texture parameters decrease.

  10. A new approach to evaluate natural zeolite ability to sorb lead (Pb) from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Drosos, Evangelos I. P.; Karapanagioti, Hrissi K.

    2013-04-01

    Lead (Pb) is a hazardous pollutant commonly found in aquatic ecosystems. Among several methods available, the addition of sorbent amendments to soils or sediments is attractive, since its application is relatively simple, while it can also be cost effective when a low cost and re-usable sorbent is used; e.g. natural zeolites. Zeolites are crystalline aluminosilicates with a three-dimensional structure composed of a set of cavities occupied by large ions and water molecules. Zeolites can accommodate a wide variety of cations, such as Na+, K+, Ca2+, Mg2+, which are rather loosely held and can readily be exchanged for others in an aqueous solution. Natural zeolites are capable of removing cations, such as lead, from aqueous solutions by ion exchange. There is a wide variation in the cation exchange capacity (CEC) of natural zeolites because of the different nature of various zeolites cage structures, natural structural defects, adsorbed ions, and their associated gangue minerals. Naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals, such as clays and feldspars, metals, quartz, or other zeolites as well. These impurities affect the CEC even for samples originated from the same region but from a different source. CEC of the material increases with decreasing impurity content. Potentially exchangeable ions in such impurities do not necessarily participate in ion exchange mechanism, while, in some cases, impurities may additionally block the access to active sites. For zeoliferous rocks having the same percentage of a zeolitic phase, the CEC increases with decreasing Si/Al ratio, as the more Si ions are substituted by Al ions, the more negative the valence of the matrix becomes. Sodium seems to be the most effective exchangeable ion for lead. On the contrary, it is unlikely that the potassium content of the zeolite would be substituted. A pretreatment with high concentration solutions of Na, such as 2 M NaCl, can

  11. Transferable force-field for modelling of CO2, N2, O2 and Ar in all silica and Na+ exchanged zeolites

    NASA Astrophysics Data System (ADS)

    Vujić, Bojan; Lyubartsev, Alexander P.

    2016-05-01

    In this work we propose a new force field for modelling of adsorption of CO2, N2, O2 and Ar in all silica and Na+ exchanged Si-Al zeolites. The force field has a standard molecular-mechanical functional form with electrostatic and Lennard-Jones interactions satisfying Lorentz-Berthelot mixing rules and thus has a potential for further extension in terms of new molecular types. The parameters for the zeolite framework atom types are optimized by an iterative procedure minimizing the difference with experimental adsorption data for a number of different zeolite structures and Si:Al ratios. The new force field shows a good agreement with available experimental data including those not used in the optimization procedure, and which also shows a reasonable transferability within different zeolite topologies. We suggest a potential usage in screening of different zeolite structures for carbon capture and storage process, and more generally, for separation of other gases.

  12. Factors affecting the adsorption of chromium (VI) on activated carbon

    SciTech Connect

    Yavuz, R.; Orbak, I.; Karatepe, N.

    2006-09-15

    The aim of this investigation was to determine the adsorption behavior of chromium (VI) on two different activated carbon samples produced from Tuncbilek lignite. The effects of the initial chromium (VI) concentration (250-1000 mg/L), temperature (297-323 K) and pH (2.0-9.5) on adsorption were investigated systematically. The effectiveness of the parameters on chromium adsorption was found to be in the order of pH, the initial Cr(VI) concentration and the temperature. Increasing the pH from 2.0 to 9.5 caused a decrease in adsorption. However, the adsorption was increased by increasing the initial Cr(VI) concentration and temperature. The multilinear mathematical model was also developed to predict the Cr(VI) adsorption on activated carbon samples within the experimental conditions.

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

    PubMed

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

    2007-06-01

    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

  14. Cost and performance of activated carbon injection for mercury control

    SciTech Connect

    2006-08-15

    Activated carbon injection (ACI) is one technology being developed to absorb mercury from mercury emitted from coal-fired power plants. In 2003/04, the USDOE and NETL selected 14 projects to test and evaluate mercury control technologies. While field testing is still ongoing, DOE/NETL recently completed an economic analysis of mercury control for six test sites spanning three ACI variations - conventional powdered activated carbon (PAC), brominated PAC and conventional PAC combined with a sorbent enhancement additive (SEA) applied to the coal. To evaluate the progress of the field testing program and discern the performance of ACI, a data adjustment methodology was developed to account for baseline methane capture. This data were used to perform economic analyses to achieve low, mid and high levels of mercury control. The costs are given in the article. Full details are available on the DOE/NETL website, www.netl.doe.gov. 2 figs., 1 photo.

  15. Synthesis and characterization of carbon nanotube from coconut shells activated carbon

    NASA Astrophysics Data System (ADS)

    Melati, A.; Hidayati, E.

    2016-03-01

    Carbon nanotubes (CNTs) have been explored in almost every single cancer treatment modality, including drug delivery, lymphatic targeted chemotherapy, photodynamic therapy, and gene therapy. They are considered as one of the most promising nanomaterial with the capability of both detecting the cancerous cells and delivering drugs or small therapeutic molecules to the cells. CNTs have unique physical and chemical properties such as high aspect ratio, ultralight weight, high mechanical strength, high electrical conductivity, and high thermal conductivity. Coconut Shell was researched as active carbon source on 500 - 600°C. These activated carbon was synthesized becomes carbon nanotube and have been proposed as a promising tool for detecting the expression of indicative biological molecules at early stage of cancer. Clinically, biomarkers cancer can be detected by CNT Biosensor. We are using pyrolysis methods combined with CVD process or Wet Chemical Process on 600°C. Our team has successfully obtained high purity, and aligned MWCNT (Multi Wall Nanotube) bundles on synthesis CNT based on coconut shells raw materials. CNTs can be used to cross the mammalian cell membrane by endocytosis or other mechanisms. SEM characterization of these materials have 179 nm bundles on phase 83° and their materials compound known by using FTIR characterization.

  16. Formation of carboxylic acids from alcohols and olefins in zeolite H-ZSM-5 under mild conditions via trapping of alkyl carbenium ions with carbon monoxide: An in situ {sup 13}C solid state NMR study

    SciTech Connect

    Stepanov, A.G.; Luzgin, M.V.; Romannikov, V.N.; Sidelnikov, V.N.; Zamaraev K.I.

    1996-12-01

    Using in situ {sup 13}C solid state MAS NMR (for some reagents in combination with ex situ GC-MS), it is shown that butyl alcohols and olefins (ethene, isobutene, octene-1) undergo carbonylation to form carboxylic acids (the Koch reaction) with high conversion on zeolite H-ZSM-5 at 296-373 K. The reactions proceed without application of pressurized conditions, just upon coadsorption of CO and alcohols or CO, H{sub 2}O, and olefins on zeolite. The observed Koch reaction under mild conditions provides strong evidence for the formation of alkyl carbenium ions from alcohols and olefins on the zeolites as crucial reaction intermediates. Of the family of carbenium ions, CO reacts selectively with tertiary cations to produce tertiary carboxylic acids, unless the carbonylated molecule is too large for more bulky tertiary moieties to be accommodated and carbonylated in the narrow pores of H-ZSM05. Thus, t-BuOH, i-BuOH, and isobutene produce trimethylacetic acid with high selectivity and conversion, while ethene transforms selectively into 2-methyl-2-ethyl butyric acid. Reaction of octene-1 molecules with CO and H{sub 2}O results in acids of the C{sub 8}H{sub 17}COOH and C{sub 16}H{sub 33}COOH families with predominantly linear hydrocarbon chains. The data obtained may open up new possibilities in using solid acids in organic synthesis as carbonylation catalysts under mild conditions i.e., low temperature and normal atmospheric pressure. 55 refs., 8 figs.

  17. Activated carbon becomes active for oxygen reduction and hydrogen evolution reactions.

    PubMed

    Yan, Xuecheng; Jia, Yi; Odedairo, Taiwo; Zhao, Xiaojun; Jin, Zhao; Zhu, Zhonghua; Yao, Xiangdong

    2016-06-21

    We utilized a facile method for creating unique defects in the activated carbon (AC), which makes it highly active for the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). The ORR activity of the defective AC (D-AC) is comparable to the commercial Pt/C in alkaline medium, and the D-AC also exhibits excellent HER activity in acidic solution. PMID:27277286

  18. Carbon dioxide capturing technologies: a review focusing on metal organic framework materials (MOFs).

    PubMed

    Sabouni, Rana; Kazemian, Hossein; Rohani, Sohrab

    2014-04-01

    In this study, a relevant literature has been reviewed focusing on the carbon dioxide capture technologies in general, such as amine-based absorption as conventional carbon dioxide capturing technology, aqueous ammonia-based absorption, membranes, and adsorption material (e.g., zeolites, and activated carbons). In more details, metal organic frameworks (MOFs) as new emerging technologies for carbon dioxide adsorption are discussed. The MOFs section is intended to provide a comprehensive overview of MOFs including material characteristics and synthesis, structural features, CO2 adsorption capacity, heat of adsorption and selectivity of CO2. PMID:24338107

  19. [Adsorption of perfluorooctanesulfonate (PFOS) onto modified activated carbons].

    PubMed

    Tong, Xi-Zhen; Shi, Bao-You; Xie, Yue; Wang, Dong-Sheng

    2012-09-01

    Modified coal and coconut shell based powdered activated carbons (PACs) were prepared by FeCl3 and medium power microwave treatment, respectively. Batch experiments were carried out to evaluate the characteristics of adsorption equilibrium and kinetics of perfluorooctanesulfonate (PFOS) onto original and modified PACs. Based on pore structure and surface functional groups characterization, the adsorption behaviors of modified and original PACs were compared. The competitive adsorption of humic acid (HA) and PFOS on original and modified coconut shell PACs were also investigated. Results showed that both Fe3+ and medium power microwave treatments changed the pore structure and surface functional groups of coal and coconut shell PACs, but the changing effects were different. The adsorption of PFOS on two modified coconut shell-based PACs was significantly improved. While the adsorption of modified coal-based activated carbons declined. The adsorption kinetics of PFOS onto original and modified coconut shell-based activated carbons were the same, and the time of reaching adsorption equilibrium was about 6 hours. In the presence of HA, the adsorption of PFOS by modified PAC was reduced but still higher than that of the original. PMID:23243870

  20. Liquid Phase Adsorption of α-Tocopherol by Activated Carbon

    NASA Astrophysics Data System (ADS)

    Bono, Awang; Ming, Chu Chi; Sundang, Murni

    α-Tocopherol or commonly called vitamin E can be found in major commercial vegetable oils such as soya oil and palm oil. However the existence in these oil is in low concentration. The recovery of low concentration of α-tocopherol from palm oils is increasingly popular. Adsorption technique for the recovery of α-tocopherol from palm oil is believed to be much lower in cost and more effective. As a case study in this work, activated carbon is chosen as the adsorbent and ethanol as the solvent. The adsorption equilibria of α-tocopherol onto activated carbon was conducted in batch and the concentration of α-tocopherol was identified by LCMS. Langmuirian monolayer adsorption theory was used for the analysis of the isotherm equilibria. The adsorptivity of α-tocopherol onto activated carbon was identified. The adsorption equilibria at low concentration found to be linear. The breakthrough curve was then generated using model assuming isothermal, single transition trace component with intraparticle diffusion. Sensitivity test on the curve indicated that the system is very sensitive to changes in diffusitivity and passive to changes on the equilibrium constant.

  1. Restricted dynamics of molecular hydrogen confined in activated carbon nanopores

    SciTech Connect

    Contescu, Cristian I; Saha, Dipendu; Gallego, Nidia C; Mamontov, Eugene; Kolesnikov, Alexander I; Bhat, Vinay V

    2012-01-01

    Quasi-elastic neutron scattering was used for characterization of dynamics of molecular hydrogen confined in narrow nanopores of two activated carbon materials: PFAC (derived from polyfurfuryl alcohol) and UMC (ultramicroporous carbon). Fast, but incomplete ortho-para conversion was observed at 10 K, suggesting that scattering originates from the fraction of unconverted ortho isomer which is rotation-hindered because of confinement in nanopores. Hydrogen molecules entrapped in narrow nanopores (<7 ) were immobile below 22-25 K. Mobility increased rapidly with temperature above this threshold, which is 8 K higher than the melting point of bulk hydrogen. Diffusion obeyed fixed-jump length mechanism, indistinguishable between 2D and 3D processes. Thermal activation of diffusion was characterized between ~22 and 37 K, and structure-dependent differences were found between the two carbons. Activation energy of diffusion was higher than that of bulk solid hydrogen. Classical notions of liquid and solid do not longer apply for H2 confined in narrow nanopores.

  2. Activated carbon adsorbents from waste tires for air quality control

    SciTech Connect

    Lehmann, C.M.B.; Rostam-Abadi, M.; Rood, M.J.; Hsi, H.C.

    1999-07-01

    This study evaluates methodologies for utilizing waste tire rubber to produce carbonaceous adsorbents for use in air quality control operations. Such an approach provides a two-fold environmental and economic benefit. A recycling path is developed for waste tire rubber and new adsorbents are produced from a low cost feedstock for use in environmentally-related operations. Bench-scale and pilot-scale quantities of tire-derived activated carbon (TDAC) were produced from waste tire rubber. Raw tire rubber samples and devolatilized tire char were obtained from several US vendors. The raw samples were analyzed using proximate, ultimate, and elemental analyses. Batches of activated carbon samples were prepared using a bench-scale fixed-tubular reactor to prepare {approximately}10 g samples and a fluidized-bed reactor to prepare {approximately}100 g quantities. About 25 kg of activated carbon was also produced at a pilot-scale commercial facility. The resulting TDACs were then characterized by nitrogen adsorption at 77K. The sample surface areas were determined by the BET method, and the pore size distribution (PSD) was evaluated using the BJH model, and a 3-D PSD model. Performance of the TDACs was evaluated in their ability to remove gaseous mercury species from simulated power-plant flue-gas streams, and for the removal of organic compounds (e.g., acetone and 1,1,1-trichloroethane) from flowing gas streams.

  3. The use of zeolites to generate PET phantoms for the validation of quantification strategies in oncology

    SciTech Connect

    Zito, Felicia; De Bernardi, Elisabetta; Soffientini, Chiara; Canzi, Cristina; Casati, Rosangela; Gerundini, Paolo; Baselli, Giuseppe

    2012-09-15

    Purpose: In recent years, segmentation algorithms and activity quantification methods have been proposed for oncological {sup 18}F-fluorodeoxyglucose (FDG) PET. A full assessment of these algorithms, necessary for a clinical transfer, requires a validation on data sets provided with a reliable ground truth as to the imaged activity distribution, which must be as realistic as possible. The aim of this work is to propose a strategy to simulate lesions of uniform uptake and irregular shape in an anthropomorphic phantom, with the possibility to easily obtain a ground truth as to lesion activity and borders. Methods: Lesions were simulated with samples of clinoptilolite, a family of natural zeolites of irregular shape, able to absorb aqueous solutions of {sup 18}F-FDG, available in a wide size range, and nontoxic. Zeolites were soaked in solutions of {sup 18}F-FDG for increasing times up to 120 min and their absorptive properties were characterized as function of soaking duration, solution concentration, and zeolite dry weight. Saturated zeolites were wrapped in Parafilm, positioned inside an Alderson thorax-abdomen phantom and imaged with a PET-CT scanner. The ground truth for the activity distribution of each zeolite was obtained by segmenting high-resolution finely aligned CT images, on the basis of independently obtained volume measurements. The fine alignment between CT and PET was validated by comparing the CT-derived ground truth to a set of zeolites' PET threshold segmentations in terms of Dice index and volume error. Results: The soaking time necessary to achieve saturation increases with zeolite dry weight, with a maximum of about 90 min for the largest sample. At saturation, a linear dependence of the uptake normalized to the solution concentration on zeolite dry weight (R{sup 2}= 0.988), as well as a uniform distribution of the activity over the entire zeolite volume from PET imaging were demonstrated. These findings indicate that the {sup 18}F-FDG solution

  4. The effects of activation temperature on physico-chemical characteristics of activated carbons derived from biomass wastes

    NASA Astrophysics Data System (ADS)

    Sutrisno, Bachrun; Hidayat, Arif

    2015-12-01

    This research focused on investigating in the effect of activation temperature on the physico-chemical properties of palm empty fruit bunch (PEFB) based activated carbon prepared by physical activation with carbon dioxide. The activation temperature was studied in the range of 400-800°C by keeping the activation temperature at 800°C for 120 min. It was found that the porous properties of activated carbon decreased with an increase in carbonization temperature. The activated carbons prepared at the highest activation temperature at 800°C and activation time of 120 min gave the activated carbon with the highest of BET surface area and pore volume of 938 m2/g and 0.4502 cm3/g, respectively

  5. Enhanced photocatalytic activity of titanium dioxide by nut shell carbon.

    PubMed

    Shi, Xiaoliang; Wang, Sheng; Dong, Xuebin; Zhang, Qiaoxin

    2009-08-15

    Nut shell carbon (NSC)-nanotitanium dioxide (TiO(2)) composites were prepared by sol-gel method. Photocatalytic activity on degradation of dye Rhodamine B was studied. X-ray diffraction, field emission scanning electron microscopy, Brunauer-Emmett-Teller surface area, pore size distribution, ultraviolet-vis light absorption spectrum, and photoluminescence spectrum were carried out to characterize the composite catalyst. The results indicated that the photocatalytic activity of NSC-nano-TiO(2) composites was much higher than P25 (Degussa). NSC could greatly absorb the organic substance and oxygen of solution because of its large surface area. PMID:19200653

  6. THE EFFECT OF POWERED ACTIVATED CARBON IN A PETROLEUM REFINERY ACTIVATED SLUDGE TREATMENT SYSTEM

    EPA Science Inventory

    The purpose of this research program was to determine the effect of the addition of powdered activated carbon (PAC) to refinery activated sludge systems. Bench-scale and full-scale tests were performed. A wide range of PAC concentrations and sludge ages were evaluated. Bench-scal...

  7. EVALUATION OF FULL SCALE ACTIVATED SLUDGE SYSTEMS UTILIZING POWDERED ACTIVATED CARBON ADDITION WITH WET AIR REGENERATION

    EPA Science Inventory

    The addition of powdered activated carbon (PAC) to activated sludge systems is a proven method of wastewater treatment. Of eleven POTWs in the U.S. that were designed for PAC use, ten included wet air regeneration (WAR) for the destruction of secondary sludge solids and recovery ...

  8. Liquid-Phase Adsorption of Phenol onto Activated Carbons Prepared with Different Activation Levels.

    PubMed

    Hsieh; Teng

    2000-10-01

    The influence of the pore size distribution of activated carbon on the adsorption of phenol from aqueous solutions was explored. Activated carbons with different porous structures were prepared by gasifying a bituminous coal char to different extents of burn-off. The results of adsorption experiments show that the phenol capacity of these carbons does not proportionally increase with their BET surface area. This reflects the heterogeneity of the carbon surface for adsorption. The pore size distributions of these carbons, determined according to the Dubinin-Stoeckli equation, were found to vary with the burn-off level. By incorporating the distribution with the Dubinin-Radushkevich equation using an inverse proportionality between the micropore size and the adsorption energy, the isotherms for the adsorption of phenol onto these carbons can be well predicted. The present study has demonstrated that the heterogeneity of carbon surface for the phenol adsorption can be attributed to the different energies required for adsorption in different-size micropores. Copyright 2000 Academic Press. PMID:10998301

  9. TREATMENT OF PRODUCED OIL AND GAS WATERS WITH SURFACTANT-MODIFIED ZEOLITE

    SciTech Connect

    Lynn E. Katz; E.J. Sullivan; R.S. Bowman

    2000-04-01

    Whereas most water produced from onshore oil and gas operations is disposed via reinjection, some waters, such as those from offshore production platforms, coastal production, and some onshore wells, must be treated to remove organic constituents before the water is discharged. Current methods for reducing residual free phases and dissolved organic carbon are not always fully effective in meeting regulatory limits. In addition, cost, space requirements, and ease of use are important factors in any treatment system. Surfactant-modified zeolite (SMZ) has been used successfully to treat contaminated ground water for organic and inorganic constituents. This research will use laboratory batch and column studies to design a field system that will be used to treat produced waters to reduce dissolved and free-phase organic constituents. The system will be designed to operate simply and to have low operating costs. Methods for regeneration of the spent zeolite will also be tested, as will the treatment system at a field production site in the final project task. Research over the past six months has focused on the selection and characterization of the surfactant modified zeolite and the produced waters. The zeolite to be used in this work has been obtained from St. Cloud Mine near Winston, New Mexico. The primary surfactant to be used to modify the zeolite is hexadecyltrimethylammonium (HDTMA).

  10. Sorption of uranium(6+) and neptunium(5+) by surfactant-modified natural zeolites

    SciTech Connect

    Prikryl, J.D.; Pabalan, R.T.

    1999-07-01

    Experiments were conducted to determine the ability of surfactant-modification to enhance the ability of natural zeolites to sorb U(6+) and Np(5+). Natural zeolite material, comprised mainly of clinoptilolite and treated with the cationic surfactant hexadecyltrimethylammonium-bromide (HDTMA), was reacted with U(6+) and Np(5+) solutions open to the atmosphere and having a range of radionuclide concentration, pH, and NaCl concentration. The results indicate surfactant-modification of the zeolite enhances its ability to sorb U(6+), particularly at pHs greater than six where U(6+) sorption on unmodified zeolite is typically low due to formation of anionic U(6+) aqueous carbonate complexes. In contrast, there is little enhancement of Np(5+) sorption onto surfactant-modified zeolite. The presence of chloride anions in solution makes surfactant-modification less effective. The enhanced sorption of U(6+) is interpreted to be due to anion exchange with counterions on the external portion of a surfactant bilayer or admicelles.

  11. Converting poultry litter to activated carbon: optimal carbonization conditions and product sorption for benzene.

    PubMed

    Guo, Mingxin; Song, Weiping

    2011-12-01

    To promote utilization of poultry litter as a source material for manufacturing low-cost activated carbon (AC) that can be used in wastewater treatment, this study investigated optimal production conditions and water-borne organic sorption potential of poultry litter-based AC. Pelletized broiler litter was carbonized at different temperatures for varied time periods and activated with steam at a range of flow rate and time. The AC products were examined for quality characteristics using standard methods and for organic sorption potentials using batch benzene sorption techniques. The study shows that the yield and quality of litter AC varied with production conditions. The optimal production conditions for poultry litter-based AC were carbonization at 700 degrees C for 45 min followed by activation with 2.5 ml min(-1) steam for another 45 min. The resulting AC possessed an iodine number of 454 mg g(-1) and a specific surface area of 403 m2 g(-1). It sorbed benzene in water following sigmoidal kinetic and isothermal patterns. The sorption capacity for benzene was 23.70 mg g(-1), lower than that of top-class commercial AC. The results, together with other reported research findings, suggest that poultry litter is a reasonable feedstock for low-cost AC applicable to pre-treat wastewater contaminated by organic pollutants and heavy metals. PMID:22439566

  12. Studies of zeolite-based artificial photosynthetic systems

    NASA Astrophysics Data System (ADS)

    Zhang, Haoyu

    Y were obtained. The Ru complexes were anchored on the surface of zeolites via ion-exchange or "ship-in-bottle" synthesis. The spectroscopic properties of the NanoY-entrapped species including methyl viologen (MV2+), RuL were measured via transmission techniques. The zeolite-encapsulated species were found to have red-shift absorption and emission bands and longer MLCT life times. By incorporating both donors Ru complexes and acceptors MV2+ in NanoY, electron transfer kinetics was examined. LFP study showed a slower back-electron-transfer rate as compared to forward electron transfer. Photochemically generated long-lived charge separation is the key step in processes that aim for conversion of solar energy into chemical energy. We incorporated RuL complex on the surface of a pinhole-free zeolite membrane by quaternization of L and surrounded with intrazeolitic bipyridinium ions (N,N'-trimethyl-2,2'-bipyridinium ion, 3DQ2+). Visible-light irradiation of the Ru complex side of the membrane in the presence of a sacrificial electron donor led to formation of PVS-· on the other side. Pore-blocking disilazane-based chemistry allows for Na+ to migrate through the membrane to maintain charge balance, while keeping the 3DQ2+ entrapped in the zeolite. These results provided encouragement that the zeolite membrane based architecture has the necessary features for not only incorporating molecular assemblies with long-lived charge separation but also for ready exploitation of the spatially separated charges to store visible light energy in chemical species. The pore-narrowing strategy applied under mild conditions can be used in control-release of active substances such as drug, pesticides, and herbicides. Methyl viologen (MV2+) was chosen as the guest molecule, since it is widely used as an herbicide and its release is of interest in agricultural applications. To explore the controlled-release capability of the surface-modified zeolite, MV2+-encapsulated zeolite Y particles were

  13. Influence of process parameters on the surface and chemical properties of activated carbon obtained from biochar by chemical activation.

    PubMed

    Angın, Dilek; Altintig, Esra; Köse, Tijen Ennil

    2013-11-01

    Activated carbons were produced from biochar obtained through pyrolysis of safflower seed press cake by chemical activation with zinc chloride. The influences of process variables such as the activation temperature and the impregnation ratio on textural and chemical-surface properties of the activated carbons were investigated. Also, the adsorptive properties of activated carbons were tested using methylene blue dye as the targeted adsorbate. The experimental data indicated that the adsorption isotherms are well described by the Langmuir equilibrium isotherm equation. The optimum conditions resulted in activated carbon with a monolayer adsorption capacity of 128.21 mg g(-1) and carbon content 76.29%, while the BET surface area and total pore volume corresponded to 801.5m(2)g(-1) and 0.393 cm(3)g(-1), respectively. This study demonstrated that high surface area activated carbons can be prepared from the chemical activation of biochar with zinc chloride as activating agents. PMID:24080293

  14. System and method for coproduction of activated carbon and steam/electricity

    DOEpatents

    Srinivasachar, Srivats; Benson, Steven; Crocker, Charlene; Mackenzie, Jill

    2011-07-19

    A system and method for producing activated carbon comprising carbonizing a solid carbonaceous material in a carbonization zone of an activated carbon production apparatus (ACPA) to yield a carbonized product and carbonization product gases, the carbonization zone comprising carbonaceous material inlet, char outlet and carbonization gas outlet; activating the carbonized product via activation with steam in an activation zone of the ACPA to yield activated carbon and activation product gases, the activation zone comprising activated carbon outlet, activation gas outlet, and activation steam inlet; and utilizing process gas comprising at least a portion of the carbonization product gases or a combustion product thereof; at least a portion of the activation product gases or a combustion product thereof; or a combination thereof in a solid fuel boiler system that burns a solid fuel boiler feed with air to produce boiler-produced steam and flue gas, the boiler upstream of an air heater within a steam/electricity generation plant, said boiler comprising a combustion zone, a boiler-produced steam outlet and at least one flue gas outlet.

  15. 40 CFR 62.15275 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... activated carbon? 62.15275 Section 62.15275 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... August 30, 1999 Other Monitoring Requirements § 62.15275 How do I monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans...

  16. 40 CFR 60.1330 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... activated carbon? 60.1330 Section 60.1330 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Requirements § 60.1330 How do I monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet...

  17. 40 CFR 60.1330 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... activated carbon? 60.1330 Section 60.1330 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Requirements § 60.1330 How do I monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet...

  18. 40 CFR 60.1330 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... activated carbon? 60.1330 Section 60.1330 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Requirements § 60.1330 How do I monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet...

  19. 40 CFR 60.1820 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... activated carbon? 60.1820 Section 60.1820 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Emission Guidelines... activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans...

  20. 40 CFR 60.1330 - How do I monitor the injection rate of activated carbon?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... activated carbon? 60.1330 Section 60.1330 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Requirements § 60.1330 How do I monitor the injection rate of activated carbon? If your municipal waste combustion unit uses activated carbon to control dioxins/furans or mercury emissions, you must meet...