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1

Detecting oil dissolved gases using carbon nanotubes sensor  

Microsoft Academic Search

The detection and analysis of dissolved gases in oil is an important means to determine the early latent faults of oil-immersed power transformer. A dissolved gases in oil detection method is presented based on carbon nanotubes sensor. A kind of MWNTs (Multi-wall carbon nanotubes) gas sensor modified by mixed acid was developed based on printed circuit board to detect dissolved

Tao Chang; Xiaoxing Zhang; Wangting Liu; Caixin Sun

2010-01-01

2

Control of acid gases using a fluidized bed adsorber.  

PubMed

During incineration, secondary pollutants such as acid gases, organic compounds, heavy metals and particulates are generated. Among these pollutants, the acid gases, including sulfur oxides (SO(x)) and hydrogen chloride (HCl), can cause corrosion of the incinerator piping and can generate acid rain after being emitted to the atmosphere. To address this problem, the present study used a novel combination of air pollution control devices (APCDs), composed of a fluidized bed adsorber integrated with a fabric filter. The major objective of the work is to demonstrate the performance of a fluidized bed adsorber for removal of acid gases from flue gas of an incinerator. The adsorbents added in the fluidized bed adsorber were mainly granular activated carbon (AC; with or without chemical treatment) and with calcium oxide used as an additive. The advantages of a fluidized bed reactor for high mass transfer and high gas-solid contact can enhance the removal of acid gases when using a dry method. On the other hand, because the fluidized bed can filter particles, fine particles prior to and after passing through the fluidized bed adsorber were investigated. The competing adsorption on activated carbon between different characteristics of pollutants was also given preliminary discussion. The results indicate that the removal efficiencies of the investigated acid gases, SO(2) and HCl, are higher than 94 and 87%, respectively. Thus, a fluidized bed adsorber integrated with a fabric filter has the potential to replace conventional APCDs, even when there are other pollutants at the same time. PMID:12935758

Chiang, Bo-Chin; Wey, Ming-Yen; Yeh, Chia-Lin

2003-08-01

3

Carbonate acidizing  

SciTech Connect

The authors present the first quantitative study and complete model of the wormholing phenomenon, leading to a means of predicting and optimizing carbonate acidizing treatments. Laboratory experiments on a gypsum model system and computer simulations show that for a given geometry, wormholes can be quantified by a unique parameter, their equivalent hydraulic length. The behavior of this quantifying parameter vs. all the system parameters is studied and allows the quantitative prediction of the efficiency of an acidizing treatment. This study highlights the fractal nature of the phenomenon, which is accounted for in the equations, and the strong effect of the sample geometry. Three types of etching can be obtained: compact, wormhole type, or homogeneous. The optimum conditions for achieving the best skin decrease correspond to the creation of wormholes and can then be defined in terms of fluid reactivity and injection rate.

Daccord, G.; Touboul, E.; Lenormand, R.

1989-02-01

4

Clostridium strain which produces acetic acid from waste gases  

DOEpatents

A method and apparatus are disclosed for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, and methanol production, into useful products. The method includes introducing the waste gases into a bioreactor where they are fermented to various organic acids or alcohols by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified. In an exemplary recovery process, the bioreactor raffinate is passed through an extraction chamber into which one or more non-inhibitory solvents are simultaneously introduced to extract the product. Then, the product is separated from the solvent by distillation. Gas conversion rates can be maximized by use of centrifuges, hollow fiber membranes, or other means of ultrafiltration to return entrained anaerobic bacteria from the bioreactor raffinate to the bioreactor itself, thus insuring the highest possible cell concentration. 4 figs.

Gaddy, J.L.

1997-01-14

5

Processes to remove acid forming gases from exhaust gases  

DOEpatents

The present invention relates to a process for reducing the concentration of NO in a gas, which process comprises: (A) contacting a gas sample containing NO with a gaseous oxidizing agent to oxidize the NO to NO[sub 2]; (B) contacting the gas sample of step (A) comprising NO[sub 2] with an aqueous reagent of bisulfite/sulfite and a compound selected from urea, sulfamic acid, hydrazinium ion, hydrazoic acid, nitroaniline, sulfanilamide, sulfanilic acid, mercaptopropanoic acid, mercaptosuccinic acid, cysteine or combinations thereof at between about 0 and 100 C at a pH of between about 1 and 7 for between about 0.01 and 60 sec; and (C) optionally contacting the reaction product of step (A) with conventional chemical reagents to reduce the concentrations of the organic products of the reaction in step (B) to environmentally acceptable levels. Urea or sulfamic acid are preferred, especially sulfamic acid, and step (C) is not necessary or performed. 16 figs.

Chang, S.G.

1994-09-20

6

Method of producing pyrolysis gases from carbon-containing materials  

DOEpatents

A gasification process of improved efficiency is disclosed. A dual bed reactor system is used in which carbon-containing feedstock materials are first treated in a gasification reactor to form pyrolysis gases. The pyrolysis gases are then directed into a catalytic reactor for the destruction of residual tars/oils in the gases. Temperatures are maintained within the catalytic reactor at a level sufficient to crack the tars/oils in the gases, while avoiding thermal breakdown of the catalysts. In order to minimize problems associated with the deposition of carbon-containing materials on the catalysts during cracking, a gaseous oxidizing agent preferably consisting of air, oxygen, steam, and/or mixtures thereof is introduced into the catalytic reactor at a high flow rate in a direction perpendicular to the longitudinal axis of the reactor. This oxidizes any carbon deposits on the catalysts, which would normally cause catalyst deactivation.

Mudge, Lyle K. (Richland, WA); Brown, Michael D. (West Richland, WA); Wilcox, Wayne A. (Kennewick, WA); Baker, Eddie G. (Richland, WA)

1989-01-01

7

What are functional ionic liquids for the absorption of acidic gases?  

PubMed

As a kind of novel and efficient material, ionic liquids (ILs) are used for capture of acidic gases including SO2 and CO2 from flue gas. Due to very low content of acidic gases in flue gas, it is important to find functional ILs to absorb the acidic gases. However, up to now, there is no criterion to distinguish if the ILs are functional or not before use, which greatly influences the design of functional ILs. In this work, a series of ILs were synthesized and used to determine functional or normal ILs for the capture of acidic gases. It has been found that the pKa of organic acids forming the anion of ILs can be used to differentiate functional ILs from normal ILs for the capture of acidic gases from flue gas. If the pKa of an organic acid is larger than that of sulfurous acid (or carbonic acid), the ILs formed by the organic acid can be called functional ILs for SO2 (or CO2) capture, and it can have a high absorption capacity of SO2 (or CO2) with low SO2 (or CO2) concentrations. If not, the IL is just a normal IL. The pKa of organic acids can also be used to explain the absorption mechanism and guide the synthesis of functional ILs. PMID:23360403

Ren, Shuhang; Hou, Yucui; Tian, Shidong; Chen, Xiumei; Wu, Weize

2013-02-28

8

Method for removing acid gases from a gaseous stream  

DOEpatents

In a process for hydrocracking a heavy aromatic polynuclear carbonaceous feedstock containing reactive alkaline constituents to produce liquid hydrocarbon fuels boiling below about 475.degree. C. at atmospheric pressure by contacting the feedstock with hydrogen in the presence of a molten metal halide catalyst, thereafter separating a gaseous stream containing hydrogen, at least a portion of the hydrocarbon fuels and acid gases from the molten metal halide and regenerating the molten metal halide, thereby producing a purified molten metal halide stream for recycle to the hydrocracking zone, an improvement comprising; contacting the gaseous acid gas, hydrogen and hydrocarbon fuels-containing stream with the feedstock containing reactive alkaline constituents to remove acid gases from the acid gas containing stream. Optionally at least a portion of the hydrocarbon fuels are separated from gaseous stream containing hydrogen, hydrocarbon fuels and acid gases prior to contacting the gaseous stream with the feedstock.

Gorin, Everett (San Rafael, CA); Zielke, Clyde W. (McMurray, PA)

1981-01-01

9

Carbon isotopic composition of deep carbon gases in an ombrogenous peatland, northwestern Ontario, Canada  

SciTech Connect

Radiocarbon dating and carbon isotope analyses of deep peat and gases in a small ombrogenous peatland in northwestern Ontario reveals the presence of old gases at depth that are 1000-2000 yr younger than the enclosing peat. The authors suggest that the most likely explanation to account for this age discrepancy is the downward movement by advection of younger dissolved organic carbon for use by fermentation and methanogens bacteria. This study identifies a potentially large supply of old carbon gases in peatlands that should be considered in global carbon models of the terrestrial biosphere.

Aravena, R. (Univ. of Waterloo, Ontario (Canada). Center for Groundwater Research and Wetlands Research Center); Warner, B.G. (Univ. of Waterloo, Ontario (Canada). Wetlands Research Center and Dept. of Geography); Charman, D.J. (Univ. of Plymouth, Devon (United Kingdom). Dept. of Geographical Sciences); Belyea, L.R. (Queen Mary and Westfield College, London (United Kingdom). School of Biological Sciences); Mathur, S.P. (Foxleigh Crescent, Kanata, Ontario (Canada)); Dinel, H. (Center for Land and Biological Resources Research, Agriculture Canada, Ontario (Canada))

1993-01-01

10

Carbon isotopic composition of deep carbon gases in an ombrogenous peatland, northwestern Ontario, Canada  

Microsoft Academic Search

Radiocarbon dating and carbon isotope analyses of deep peat and gases in a small ombrogenous peatland in northwestern Ontario reveals the presence of old gases at depth that are 1000-2000 yr younger than the enclosing peat. The authors suggest that the most likely explanation to account for this age discrepancy is the downward movement by advection of younger dissolved organic

R. Aravena; B. G. Warner; D. J. Charman; L. R. Belyea; S. P. Mathur; H. Dinel

1993-01-01

11

THE SOLUBILITY OF ACID GASES IN METHANOL  

EPA Science Inventory

The report describes a thermodynamic model developed to predict phase-equilibrium behavior in a methanol/carbon-dioxide/nitrogen/hydrogen-sulfide system based on parameters determined from binary vapor/liquid equilibrium data available in the literature. Model predictions are com...

12

Fullerenes: An extraterrestrial carbon carrier phase for noble gases  

PubMed Central

In this work, we report on the discovery of naturally occurring fullerenes (C60 to C400) in the Allende and Murchison meteorites and some sediment samples from the 65 million-year-old Cretaceous/Tertiary boundary layer (KTB). Unlike the other pure forms of carbon (diamond and graphite), fullerenes are extractable in an organic solvent (e.g., toluene or 1,2,4-trichlorobenzene). The recognition of this unique property led to the detection and isolation of the higher fullerenes in the Kratschmer/Huffmann arc evaporated graphite soot and in the carbon material in the meteorite and impact deposits. By further exploiting the unique ability of the fullerene cage structure to encapsulate and retain noble gases, we have determined that both the Allende and Murchison fullerenes and the KTB fullerenes contain trapped noble gases with ratios that can only be described as extraterrestrial in origin.

Becker, Luann; Poreda, Robert J.; Bunch, Ted E.

2000-01-01

13

Mixed waste ferrite as a novel sorbent for carbon dioxide derived from flue gases  

Microsoft Academic Search

Ferrite is a potential sorbent for flue gases such as CO2, H2S and SO2. This paper discusses the adsorption and decomposition of CO2 into carbon by hydrogen-activated waste ferrites prepared from Berkeley Pit acid mine water (Butte, MT). The decomposition effectiveness of these waste ferrites was studied at 300 °C and compared with the synthetic magnetite obtained from ferrous sulfate

R. K. Mehta; K. Yang; M. Misra

1996-01-01

14

MULTIPOLLUTANT MERCURY AND ACID GASES CONTROL TECHNOLOGY  

EPA Science Inventory

Plans are to continue testing for acid gas, mercury and NOx removal on baseline CFB operation with lime slurry, then use modified lime hydrates and slurries, and modified calcium silicates as additives for enhanced mercury and SO2 removal. Also, data from a coal-fired utility b...

15

Process for removal of ammonia and acid gases from contaminated waters  

DOEpatents

Contaminating basic gases, i.e., ammonia, and acid gases, e.g., carbon dioxide, are removed from process waters or waste waters in a combined extraction and stripping process. Ammonia in the form of ammonium ion is extracted by an immiscible organic phase comprising a liquid cation exchange component, especially an organic phosphoric acid derivative, and preferably di-2-ethyl hexyl phosphoric acid, dissolved in an alkyl hydrocarbon, aryl hydrocarbon, higher alcohol, oxygenated hydrocarbon, halogenated hydrocarbon, and mixtures thereof. Concurrently, the acidic gaseous contaminants are stripped from the process or waste waters by stripping with steam, air, nitrogen, or the like. The liquid cation exchange component has the ammonia stripped therefrom by heating, and the component may be recycled to extract additional amounts of ammonia.

King, C. Judson (Kensington, CA); MacKenzie, Patricia D. (Berkeley, CA)

1985-01-01

16

Process for removal of ammonia and acid gases from contaminated waters  

DOEpatents

Contaminating basic gases, i.e., ammonia and acid gases, e.g., carbon dioxide, are removed from process waters or waste waters in a combined extraction and stripping process. Ammonia in the form of ammonium ion is extracted by an immiscible organic phase comprising a liquid cation exchange component, especially an organic phosphoric acid derivative, and preferably di-2-ethyl hexyl phosphoric acid, dissolved in an alkyl hydrocarbon, aryl hydrocarbon, higher alcohol, oxygenated hydrocarbon, halogenated hydrocarbon, and mixtures thereof. Concurrently, the acidic gaseous contaminants are stripped from the process or waste waters by stripping with stream, air, nitrogen, or the like. The liquid cation exchange component has the ammonia stripped therefrom by heating, and the component may be recycled to extract additional amounts of ammonia.

King, C.J.; Mackenzie, P.D.

1982-09-03

17

Molecular Structure of Carbonic acid  

NSDL National Science Digital Library

The hypothetical acid formed with carbon dioxide and water; it is only in the H2CO3 form when in solution. This acid is found in everyday products, the most prominent of which include carbonated beverages. The conversion of carbonic acid into water and carbon dioxide in sodas is the reason the beverage looses the bubbling.

2002-09-10

18

Insights into deep carbon derived from noble gases  

NASA Astrophysics Data System (ADS)

Science and society are faced with two challenges that are inextricably linked: fossil-fuel energy dependence and rising levels of atmospheric carbon dioxide. Management of remaining hydrocarbon resources, the search for cleaner fuels and increasing interest in subsurface carbon storage all require a better understanding of the deep terrestrial carbon cycle. The coupling of noble gas and carbon chemistry provides an innovative approach to understanding this deep carbon. Whereas carbon geochemistry and isotopic signatures record the history of inorganic and organic reactions that control carbon mobility, the inert noble gases provide unique tracers of fluid origin, transport and age. Together, they have been used to show that groundwater has a key role as both the sink for geologically sequestered carbon dioxide, and in the transport and emplacement of hydrocarbon gas deposits. Furthermore, these tracers have also been used to show that groundwater and subsurface microbiology jointly influence the formation and alteration of fossil-fuel deposits to an extent not previously recognized. The age and distribution of groundwater in fractures in the Earth's crust exert important controls on the Earth's deepest microbial communities.

Lollar, B. Sherwood; Ballentine, C. J.

2009-08-01

19

Automated Low-Pressure Carbonate Eluent Ion Chromatography System with Postsuppressor Carbon Dioxide Removal for the Analysis of Atmospheric Gases and Particles  

Microsoft Academic Search

We present a low-pressure, automated, semi-continuous Gas-Particle Ion Chromatograph to measure soluble ionogenic gases and soluble ionic constituents of PM2.5. The system utilizes a short separation column, an isocratic carbonate eluent and post suppressor CO2 removal. Measured constituents include ammonium, nitrate, and sulfate in the particle fraction, and nitric acid, sulfur dioxide, and ammonia among soluble gases. Two independent sampling

S. M. Rahmat Ullah; Allen Williams; Purnendu K. Dasgupta

2005-01-01

20

Arterial blood carbonic Acid inversely determines lactic and organic acids.  

PubMed

Objective: To establish that arterial blood carbonic acid varies inversely with lactic acid in accordance with bicarbonate exchanging for lactate across cell membranes through the anion exchange mechanism to maintain the Gibbs-Donnan equilibrium. Study Design: Over 5 years, lactate was measured on all blood gases taken from neonatal admissions, as well as organic acid whenever electrolytes were required. Results: Arterial blood gases from 63 infants given high calcium TPN were analyzed. Twenty two needed continuous positive airways pressure (CPAP) only and 31 intermittent positive pressure ventilation (IPPV) and surfactant followed by CPAP to treat respiratory distress syndrome in 51 and meconium aspiration syndrome in 2. All survived and were free of infection. Excluded gases were those with high and falling lactate soon after delivery representing perinatal asphyxia, and those on dexamethasone. Strong inverse relations between carbonic and lactic acids were found at all gestational ages and, independent of glomerular filtration, between carbonic and organic acids. Lactate (mmol/L) = 62.53 X PCO2 (-0.96)(mmHg) r(2) 0.315, n 1232, p <0.001. Sixty divided by PCO2 is a convenient measure of physiological lactate at any given PCO2. In the first week, 9.13 ± 2.57% of arterial gases from infants on IPPV had lactates above 120/PCO2, significantly more than 4.74 ± 2.73% on CPAP (p<0.05) and 2.47 ± 2.39% on no support. Conclusion: Changes in arterial blood carbonic acid cause immediate inverse changes in lactic acid, because their anions interchange across cell membranes according to the Gibbs -Donnan equilibrium. Increasing PCO2 from 40 to 120 mmHg decreased lactate from 1.5 mmol/L to 0.5 mmol/L, so that the sum of carbonic and lactic acids increased from 2.72 mmol/L to only 4.17 mmol/L. This helps explain the neuroprotective effect of hypercapnoea and highlights the importance of avoiding any degree of hypocapnoea in infants on IPPV. PMID:24392387

Aiken, Christopher Geoffrey Alexander

2013-11-01

21

Soluble species in the Arctic summer troposphere: Acidic gases, aerosols, and precipitation  

Microsoft Academic Search

We report here the distribution of selected acidic gases and aerosol species in the North American Arctic and sub-Arctic summer troposphere. The summertime troposphere is an acidic environment, with HCOOH and CH3COOH the principal acidic gases and acidic sulfate aerosols dominating the particulate phase. Our data show tht the acidic gas and aerosol composition is uniform on a large spatial

R. W. Talbot; A. S. Vijgen; R. C. Harriss

1992-01-01

22

Nadir Sounding of Carbon Gases using SCIAMACHY Near Infrared Channels  

NASA Astrophysics Data System (ADS)

The Beer InfraRed Retrieval Algorithm (BIRRA) and Column EstimatoR Vertical InfraRed Sounding Atmosphere (CERVISA) codes have been designed to retrieve vertical column den-sities (VCDs) of atmospheric gases in the near and thermal infrared (NIR,TIR) region of the electromagnetic spectrum by means of non-linear least squares fitting of radiances. As part of the operational SCIAMACHY level 1-2 processor, BIRRA is currently used for the specific retrieval of carbon monoxide (CO) VCDs exploiting the fitting window 4282-4301 cm-1 within the SCIAMACHY channel 8. Using appropriate fitting windows in channel 6, BIRRA also allows to gain information on greenhouse gases such as methane and carbon dioxide. Unfortunately, the increasing number of dead and bad pixels -specially in the NIR channels -reduces the available spectral information and consequently makes the VCDs retrieval more and more challenging. The proper choice of the pixel mask, fitting window, auxiliary fit parameters, as well as the filtering of the Level 2 data is crucial for obtaining a high quality atmospheric product. For validation of BIRRA the closely related CERVISA code is used to retrieve CO and CH4 from nadir infrared sounding data of AIRS, IASI, or TES. BIRRA and CERVISA share a large portion of modules, e.g., for line-by-line absorption and the nonlinear least squares solver; the essential difference is the part of the forward model devoted to radiative transfer through the atmosphere, i.e., Beer's law for the NIR versus Schwarzschild's equation for the TIR. CERVISA retrieval results are compared both to the operational products of the TIR sounder and to the SCIAMACHY-BIRRA product. In this work, we present recent results of carbon monoxide and methane retrievals.

Gimeno García, Sebastián; Schreier, Franz; Lichtenberg, Günter; Slijkhuis, Sander; Hess, Michael; Aberle, Bernd

23

Atmospheric Trace Gases, Carbon Isotopes, Radionuclides, and Aerosols: Other Trace Gases Data from the Carbon Dioxide Information Analysis Center (CDIAC)  

DOE Data Explorer

(Scroll down to find Other Trace Gases data, a subheading under the broader heading of Atmospheric Trace Gases, etc.) CDIAC products are indexed and searchable through a customized interface powered by ORNL's Mercury search engine. Products include numeric data packages, publications, trend data, atlases, models, etc. and can be searched for by subject area, keywords, authors, product numbers, time periods, collection sites, spatial references, etc. Some of the collections may also be included in the CDIAC publication Trends Online: A Compendium of Global Change Data. Most data sets, many with numerous data files, are free to download from CDIAC's ftp area. Information in this general subject areas includes: • The ALE/GAGE/AGAGE Network (updated July 2006) • Methane, Nonmethane Hydrocarbons, Alkyl Nitrates, and Chlorinated Carbon Compounds including 3 Chlorofluorocarbons (CFC-11, CFC-12, and CFC-113) in Whole-air Samples (2003) (Trends Online) • Atmospheric Fluoroform (CHF3, HFC-23) at Cape Grim, Tasmania (2000) (Trends Online) • Atmospheric Methyl Chloride (2000) • Trifluoromethyl Sulfur Pentafluoride (SF5CF3) and Sulfur Hexafluoride (SF6) from Dome Concordia (2000) (Trends Online) • EML's Stratospheric Radionuclide (RANDAB) and Trace Gas (TRACDAB) Databases (1997) • Globally Averaged Atmospheric CFC-11 Concentrations: Monthly and Annual Data for the Period 1975-1992 (1996) • Surface Water and Atmospheric Carbon Dioxide and Nitrous Oxide Observations by Shipboard Automated Gas Chromatography: Results from Expeditions Between 1977 and 1990 (1992) • Annual and Seasonal Global Variation in Total Ozone and Layer-Mean Ozone, 1958-1989 (revised 1992) (Specialized Interface)

24

Method for producing reduction gases consisting essentially of carbon monoxide and hydrogen  

Microsoft Academic Search

A single heat method of producing reduction gases which consist essentially of carbon monoxide and hydrogen for ore-reducing processes, comprises, directing a coal and water suspension into a reactor to generate combustion gases under pressure having a temperature in the range of from 1300* C. To 1500* C. And mixing the combustion gases immediately after they are formed with reduction

Tippmer

1980-01-01

25

Process for the removal of acid forming gases from exhaust gases and production of phosphoric acid  

DOEpatents

Exhaust gases are treated to remove NO or NO.sub.x and SO.sub.2 by contacting the gases with an aqueous emulsion or suspension of yellow phosphorous preferably in a wet scrubber. The addition of yellow phosphorous in the system induces the production of O.sub.3 which subsequently oxidizes NO to NO.sub.2. The resulting NO.sub.2 dissolves readily and can be reduced to form ammonium ions by dissolved SO.sub.2 under appropriate conditions. In a 20 acfm system, yellow phosphorous is oxidized to yield P.sub.2 O.sub.5 which picks up water to form H.sub.3 PO.sub.4 mists and can be collected as a valuable product. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50.degree. C. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO.sub.x and SO.sub.2, alkalis that are used for flue gas desulfurization are preferred. With this process, better than 90% of SO.sub.2 and NO in simulated flue gas can be removed. Stoichiometric ratios (P/NO) ranging between 0.6 and 1.5 were obtained.

Chang, Shih-Ger (El Cerrito, CA) [El Cerrito, CA; Liu, David K. (San Pablo, CA) [San Pablo, CA

1992-01-01

26

High Coverage Phases of Gases Adsorbed on Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Grand canonical Monte Carlo simulations are performed to investigate the adsorption properties of several gases (Ne, Methane, Ar, Kr, Xe) on the external surface of a carbon nanotube bundle [1]. We focus on the appearance of a second layer groove phase, which occurs once a monolayer of atoms covers the external surface. We derive from the simulations the isosteric and specific heat as a function of coverage. We analyze our results paying special attention to adatom size (commensuration), and discuss quantum corrections. We compare our findings with recent adsorption experiments [2]. [1] S.M. Gatica et al, J. Chem. Phys. 114, 3765 (2001); M.M. Calbi et al, J. Chem. Phys. 115, 9975 (2001). [2] S. Talapatra and A.D. Migone, Phys. Rev. Lett. 87, 206106 (2001); M. Muris et al, Surf. Sci. 492, 67 (2001).

Calbi, Maria M.; Gatica, Silvina M.; Bojan, Mary J.; Cole, Milton W.

2002-03-01

27

Solubility calculations for acid gases in amine blends  

SciTech Connect

Treating with alkanolamines is often used to sweeten gases containing only a few parts per million of CO/sub 2/ and H/sub 2/S. Primary amines such as monoethanolamine (MEA) have great affinity for acid gases and are able to produce high purity sweet gas; on the other hand, tertiary amines like methyldiethanolamine (MDEA) have large capacity and are easy to regenerate but, because they do not bind chemically with CO/sub 2/, they are unable to produce a sweetened gas low in this component. Recently, the use of amine blends has become a subject of potentially great commercial importance. Since, the range of possible amines and blend formulations is large, a method for predicting equilibrium solubility is needed. A rigorous thermodynamic model has been developed which uses the extended Debye-Huckel expression, is very similar to one developed for single-amine solutions, and involves the fitting of binary interaction parameters to experimental data. In this work the interaction parameters found to be important in the activity coefficient expression were fitted to each single-acid-gas single-amine subsystem using all published solubility data. The resulting model was then validated by comparing mixed-acid-gas single-amine solubility predictions with published VLE data. MEA-MDEA and DEA-MDEA blends have been studied in detail in this work. It is found that each amine contributes to the overall acid gas solubility in a nonlinear way and that the solubility curves can exhibit maxima and minima as a function of the relative concentrations of the amines.

Chakravarty, T.

1985-01-01

28

Mathematical modeling of stable carbon isotope ratios in natural gases^@?  

NASA Astrophysics Data System (ADS)

A new approach is presented for mathematical modeling of stable carbon isotope ratios in hydrocarbon gases based on both theoretical and experimental data. The kinetic model uses a set of parallel first-order gas generation reactions in which the relative cracking rates of isotopically substituted (k?) and unsubstituted (k) bonds are represented by the equation k?/k=(Af?/Af) exp(-?Ea/RT), where R is the gas constant and T is temperature. Quantum chemistry calculations have been used to estimate the entropic (A f?/A f) and enthalpic (?Ea) terms for homolytic bond cleavage in a variety of simple molecules. For loss of a methyl group from a short-chain n-alkane (? C 6), for example, we obtain an average ?Ea of 42.0 cal/mol and an average A f?/A f of 1.021. Expressed differently, 13C-methane generation is predicted to be 2.4% (24‰) slower than 12C-methane generation (from a short-chain n-alkane) in a sedimentary basin at 200°C but only 0.7% (7‰) slower in a laboratory heating experiment at 500°C. Similar calculations carried out for homolytic bond cleavage in other molecules show that with few exceptions, ?Ea varies between 0 and 60 cal/mol and A f?/A f between 1.00 and 1.04. Examination of this larger data set reveals: (1) a weak sigmoid relationship between ?Ea and bond dissociation energy; and (2) a strong positive correlation between ?Ea and A f?/A f. The significance of these findings is illustrated by fitting a kinetic model to chemical and isotopic data for the generation of methane from n-octadecane under isothermal closed-system conditions. For a specific temperature history, the fitted model provides quantitative relationships among methane carbon isotope composition, total methane yield and methane generation rate which may have relevance to the cracking of oil-prone kerogens and crude oil. The observed variability of the kinetic reactivity of various methane source rocks highlights the need to apply and adequately calibrate such models with laboratory data for specific study areas. With this approach isotope data of natural gases can be used not only to estimate the time of gas generation in a sedimentary basin, but also to evaluate the source rock maturities at which specific accumulations were generated, and place constraints on trap charging histories.

Tang, Y.; Perry, J. K.; Jenden, P. D.; Schoell, M.

2000-08-01

29

Carbonation and Other Super Saturated Gases as Solution Modifiers for Improved Sensitivity in Solvent Assisted Ionization Inlet (SAII) and ESI  

NASA Astrophysics Data System (ADS)

Solvent Assisted Ionization Inlet (SAII) produces ions in a heated inlet to a mass spectrometer from aqueous and aqueous/organic solutions with high sensitivity. However, the use of acid modifiers, which typically aids electrospray ionization, generally results in ion suppression in SAII. Here we demonstrate that the use of carbonation and other super-saturated gases as solution modifiers increases analyte ion abundance and reduces metal cation adduction in SAII. Carbonation is also found to enhance electrospray ionization. The mechanistic and practical utility of carbonation in mass spectrometry is addressed.

Pagnotti, Vincent S.; Chakrabarty, Shubhashis; McEwen, Charles N.

2013-02-01

30

Carbonation and other super saturated gases as solution modifiers for improved sensitivity in solvent assisted ionization inlet (SAII) and ESI.  

PubMed

Solvent Assisted Ionization Inlet (SAII) produces ions in a heated inlet to a mass spectrometer from aqueous and aqueous/organic solutions with high sensitivity. However, the use of acid modifiers, which typically aids electrospray ionization, generally results in ion suppression in SAII. Here we demonstrate that the use of carbonation and other super-saturated gases as solution modifiers increases analyte ion abundance and reduces metal cation adduction in SAII. Carbonation is also found to enhance electrospray ionization. The mechanistic and practical utility of carbonation in mass spectrometry is addressed. PMID:23296909

Pagnotti, Vincent S; Chakrabarty, Shubhashis; McEwen, Charles N

2013-02-01

31

The Kyoto Protocol and non-CO 2 Greenhouse Gases and Carbon Sinks  

Microsoft Academic Search

Many trace constituents other than carbon dioxide affect the radiative budget of the atmosphere. The existing international agreement to limit greenhouse gases, the Kyoto Protocol, includes carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and credit for some carbon sinks. We investigate technological options for reducing emissions of these gases and the economic

J. Reilly; M. Mayer; J. Harnisch

2002-01-01

32

Indoor exposures to fine aerosols and acid gases.  

PubMed Central

Indoor exposures to aerosols and gases are associated with both indoor and outdoor air pollution sources. The identification of sources and the assessment of their relative contribution can be a complicated process due to a) the presence of numerous indoor sources, which can vary from building to building; b) the uncertainties associated with the estimation of the impact of outdoor sources on indoor air quality; c) the interactions between pollutants; and d) the importance of reactions between pollutants and indoor surfaces. It is well established that fine particles (diameter less than or equal to 2.5 microns) originating from outdoor sources such as automobiles, oil and coal combustion, incineration, and diverse industrial activities can penetrate into the indoor environment. Indoor/outdoor ratios, usually varying between 0.4 and 0.8, depend on parameters such as particle size and density, air exchange rate, and the surface-to-volume ratio of the indoor environment. Determining fine particle elemental composition makes it possible to identify the contribution of different outdoor sources. This paper focuses on the origin and the concentration of indoor aerosols and acid gases by highlighting the results from two indoor air quality studies.

Koutrakis, P; Brauer, M; Briggs, S L; Leaderer, B P

1991-01-01

33

Reaction of acid gases with mixtures of amines  

SciTech Connect

Detailed thermodynamic and kinetic models are presented in this paper which were developed for acid gas reactions with mixtures of amines. The models permit the extension of the nonequilibrium-stage approach in the simulation of gas treating plants using solvent blends. The prediction of these models indicate a potentially great improvement in sour gas treating processes. The mixing concept enables one to obtain the individual advantages of each amine for absorption as well as desorption without the disadvantages of either. In the absorber, the MEA in the blend at the top of the column serves to remove residual CO2 from the gas while throughout the rest of the column MDEA does a bulk removal job. The use of blended amines to treat natural, refinery and synthesis gases brings about a considerable improvement in absorption and a great savings in energy requirements.

Chakravarty, T.; Phukan, U.K.; Weilund, R.H.

1985-04-01

34

Organic acids tunably catalyze carbonic Acid decomposition.  

PubMed

Density functional theory calculations predict that the gas-phase decomposition of carbonic acid, a high-energy, 1,3-hydrogen atom transfer reaction, can be catalyzed by a monocarboxylic acid or a dicarboxylic acid, including carbonic acid itself. Carboxylic acids are found to be more effective catalysts than water. Among the carboxylic acids, the monocarboxylic acids outperform the dicarboxylic ones wherein the presence of an intramolecular hydrogen bond hampers the hydrogen transfer. Further, the calculations reveal a direct correlation between the catalytic activity of a monocarboxylic acid and its pKa, in contrast to prior assumptions about carboxylic-acid-catalyzed hydrogen-transfer reactions. The catalytic efficacy of a dicarboxylic acid, on the other hand, is significantly affected by the strength of an intramolecular hydrogen bond. Transition-state theory estimates indicate that effective rate constants for the acid-catalyzed decomposition are four orders-of-magnitude larger than those for the water-catalyzed reaction. These results offer new insights into the determinants of general acid catalysis with potentially broad implications. PMID:24933150

Kumar, Manoj; Busch, Daryle H; Subramaniam, Bala; Thompson, Ward H

2014-07-10

35

Plasma-chemical waste treatment of acid gases  

Microsoft Academic Search

The research to date has shown that a HâS waste-treatment process based on plasma-chemical dissociation technology is compatible with refinery and high-carbon-oxide acid-gas streams. The minor amounts of impurities produced in the plasma-chemical reactor should be treatable by an internal catalytic reduction step. Furthermore, the plasma-chemical technology appears to be more efficient and more economical than the current technology. The

J. B. L. Harkness; R. D; E. J. Daniels

1993-01-01

36

Manure Gases  

MedlinePLUS

... gases of most concern are ammonia and hydrogen sulfide. Other gases of concern include methane and carbon ... Since most of these gases in particular hydrogen sulfide are heavier-than-air, they tend to settle ...

37

Joseph Black, carbon dioxide, latent heat, and the beginnings of the discovery of the respiratory gases.  

PubMed

The discovery of carbon dioxide by Joseph Black (1728-1799) marked a new era of research on the respiratory gases. His initial interest was in alkalis such as limewater that were thought to be useful in the treatment of renal stone. When he studied magnesium carbonate, he found that when this was heated or exposed to acid, a gas was evolved that he called "fixed air" because it had been combined with a solid material. He showed that the new gas extinguished a flame, that it could not support life, and that it was present in gas exhaled from the lung. Within a few years of his discovery, hydrogen, nitrogen, and oxygen were also isolated. Thus arguably Black's work started the avalanche of research on the respiratory gases carried out by Priestley, Scheele, Lavoisier, and Cavendish. Black then turned his attention to heat and he was the first person to describe latent heat, that is the heat added or lost when a liquid changes its state, for example when water changes to ice or steam. Latent heat is a key concept in thermal physiology because of the heat lost when sweat evaporates. Black was a friend of the young James Watt (1736-1819) who was responsible for the development of early steam engines. Watt was puzzled why so much cooling was necessary to condense steam into water, and Black realized that the answer was the latent heat. The resulting improvements in steam engines ushered in the Industrial Revolution. PMID:24682452

West, John B

2014-06-15

38

Solubility of acid gases in a mixed solvent  

SciTech Connect

The solubility of hydrogen sulphide and carbon dioxide and their mixtures has been measured at 40/sup 0/ and 100/sup 0/C in a mixed solvent consisting of 20.9 wt% (2.0 M) MDEA (methyldiethanolamine), 30.5 wt% sulfolane, and 48.6 wt% water. The results have been compared with those for aqueous 2.0 M MDEA and an analogous mixed solvent, containing AMP (2-amino-2-methyl-1-propanol), which are available in the literature. At solution loadings less than 1 mol acid gas/mol MDEA, the solubility of the acid gas was lower in the mixed solvent that in the corresponding aqueous MDEA solvent; at solution loadings greater than 1 mol acid gas/mol MDEA, the reverse was true. At all loadings and at both temperatures studied, the mixed MDEA solvent absorbed equal or lesser quantities of acid gas than the comparable mixed AMP solvent. However, the shapes of the solubility curves show that the mixed MDEA solvent would be a better choice for certain industrial applications. These data were used to modify the solubility model of Deshmukh and Mather to account for the mixed solvent effects on the system thermodynamics. Results show that the model is useful as a first approximation in predicting acid gas solubilities; agreement with experiment was generally found to be within +-15%.

MacGregor, R.J.; Mather, A.E.

1987-01-01

39

Atmospheric Trace Gases from the Carbon Dioxide Information Analysis Center (CDIAC)  

DOE Data Explorer

CDIAC products are indexed and searchable through a customized interface powered by ORNL's Mercury search engine. Products include numeric data packages, publications, trend data, atlases, models, etc. and can be searched for by subject area, keywords, authors, product numbers, time periods, collection sites, spatial references, etc. Some of the collections may also be included in the CDIAC publication, Trends Online: A Compendium of Global Change Data. Most data sets, many with numerous data files, are free to download from CDIAC's ftp area. The collections under the CDIAC heading of Atmospheric Trace Gases include: Atmospheric Carbon Dioxide, Atmospheric Methane, Atmospheric Carbon Monoxide, Atmospheric Hydrogen, Isotopes in Greenhouse Gases, Radionuclides, Aerosols, and Other Trace Gases.

40

Insights into deep carbon derived from noble gases  

Microsoft Academic Search

Science and society are faced with two challenges that are inextricably linked: fossil-fuel energy dependence and rising levels of atmospheric carbon dioxide. Management of remaining hydrocarbon resources, the search for cleaner fuels and increasing interest in subsurface carbon storage all require a better understanding of the deep terrestrial carbon cycle. The coupling of noble gas and carbon chemistry provides an

B. Sherwood Lollar; C. J. Ballentine

2009-01-01

41

Vapor-liquid equilibria in the system ethanethiol + methyldiethanolamine + water in the presence of acid gases  

SciTech Connect

This investigation was carried out to determine the solubility of ethanethiol in a methyldiethanolamine (MDEA) solution. Measurements were made in the absence of acid gases, H{sub 2}H and CO{sub 2}, with individual acid gases present, and with mixtures of acid gases present. Experiments with an aqueous solution of 50 mass % MDEA were carried out at 40 and 70 C. The total pressure for most of the experiments was 6,890 kPa, which was maintained by methane. Partial pressures of ethanethiol ranged from 0.2 to 15 kPa.

Jou, F.Y.; Mather, A.E. [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical and Materials Engineering] [Univ. of Alberta, Edmonton, Alberta (Canada). Dept. of Chemical and Materials Engineering; Schmidt, K.A.G.; Ng, H.J. [DB Robinson Research Ltd., Edmonton, Alberta (Canada)] [DB Robinson Research Ltd., Edmonton, Alberta (Canada)

1999-07-01

42

Evaluation of carbon dioxide equivalent values for greenhouse gases: CEWN as a new indicator replacing GWP  

Microsoft Academic Search

A new indicator, the CEWN (Carbon Dioxide Equivalent Warming Number), is proposed as an alternative to the GWP (Global Warming Potential). CEWN is a metric where the global warming by the emission of gases is compared unifying the removal rate of each gas from the atmosphere, using carbon dioxide as a reference. To comply with the basket system of the

Akira Sekiya; Sayuri Okamoto

2010-01-01

43

Retention of mercury in activated carbons in coal combustion and gasification flue gases  

Microsoft Academic Search

To avoid the emission of toxic mercury compounds from coal combustion and gasification, efficient gas cleaning systems need to be developed. In this work, the effectiveness of activated carbons for retaining mercury in gases from coal gasification was evaluated and contrasted with the results obtained in a coal combustion atmosphere. The performance of a sulphur-loaded carbon (RBHG3) was compared with

M. Antonia Lopez-Antón; Juan M. D Tascón; M. Rosa Mart??nez-Tarazona

2002-01-01

44

Catalytic process for removing SOâ from sulfuric acid plant off gases  

Microsoft Academic Search

The invention is directed to an integrated process for reducing the SOâ content of sulfuric acid plant off gases by (1) passing the SOâ-containing feed gas to the process over a specially defined multistage oxidation catalyst to convert SOâ to SOâ, (2) absorbing the SOâ in water to form HâSOâ and (3) scrubbing the off gases with aqueous hydrogen peroxide

1976-01-01

45

Relation of Hydrogen and Methane to Carbon Monoxide in Exhaust Gases from Internal-Combustion Engines  

NASA Technical Reports Server (NTRS)

The relation of hydrogen and methane to carbon monoxide in the exhaust gases from internal-combustion engines operating on standard-grade aviation gasoline, fighting-grade aviation gasoline, hydrogenated safety fuel, laboratory diesel fuel, and auto diesel fuel was determined by analysis of the exhaust gases. Two liquid-cooled single-cylinder spark-ignition, one 9-cylinder radial air-cooled spark-ignition, and two liquid-cooled single-cylinder compression-ignition engines were used.

Gerrish, Harold C; Tessmann, Arthur M

1935-01-01

46

Atmospheric Trace Gases, Carbon Isotopes, Radionuclides, and Aerosols: Atmospheric Carbon Monoxide Data from the Carbon Dioxide Information Analysis Center (CDIAC)  

DOE Data Explorer

(Scroll down to find Atmospheric Carbon Monoxide, a subheading under the broader heading of Atmospheric Trace Gases, etc.) CDIAC products are indexed and searchable through a customized interface powered by ORNL's Mercury search engine. Products include numeric data packages, publications, trend data, atlases, models, etc. and can be searched for by subject area, keywords, authors, product numbers, time periods, collection sites, spatial references, etc. Some of the collections may also be included in the CDIAC publication Trends Online: A Compendium of Global Change Data. Most data sets, many with numerous data files, are free to download from CDIAC's ftp area. Information related to atmospheric carbon monoxide includes: • Atmospheric CO Concentrations from the CSIRO GASLAB Flask Sampling Network (Trends Online) • MAPS 1994 Correlative Atmospheric CO Mixing Ratios (1998) • Atmospheric Carbon Monoxide Mixing Ratios NOAA Climate Monitoring and Diagnostics Laboratory Cooperative Air Sampling Network, 1988-1993 (1994) Specialized Interface

47

Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution  

DOEpatents

A system is described for forming metal hydroxide from a metal carbonate utilizing a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate, in particular water-insoluble calcium carbonate or magnesium carbonate, is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide. Among other uses, the metal hydroxide formed can be employed to absorb acid gases such as carbon dioxide from a gas mixture. The invention can also generate hydrogen and oxidative gases such as oxygen or chlorine.

Rau, Gregory Hudson (Castro Valley, CA)

2012-05-15

48

The emission of biogenic sulphur gases from incubated Chinese paddy soil and its relationship with carbon dioxide  

Microsoft Academic Search

Biogeic sulphur gases emitted from terrestrial ecosystem may play an important role in the global sulphur cycle and have a profound influence on global climate change. In this paper, the emissions of volatile sulphur gases and carbon dioxide from incubated paddy soil were measured. The paddy soils were collected from Nanjing and Yangzhou, China. Six species of sulphur?containing gases were

Zhen Yang; Li Kong; Shiming Wang

1997-01-01

49

Radiolysis gases from nitric acid solutions containing HSA and HAN  

SciTech Connect

The concentration of hydrogen (H{sub 2}) in the radiolytically produced off-gas from 2.76-4.25M HNO{sub 3}/PU solutions has been found to be greatly reduced in the presence of sulfamic acid (HSA) and hydroxylamine nitrate (HAN). The H{sub 2} concentration ([H{sub 2}]) is reduced from 35 percent to about 4 percent by dilution caused from an increase in the production rates of nitrogen (N{sub 2}), nitrous oxide (N{sub 2}O), and oxygen (O{sub 2}) gases. The generation rate of H{sub 2} was not affected by HSA or HAN giving a measured radiolytic yield, G(H{sub 2}), value of 0.201 molecules/100 eV for 2.765M NO{sub 3}{sup -} solution (a value of 0.213 is predicted from previous data). The G(H{sub 2}) values are dependent on the solution nitrate concentration ([NO{sub 3}{sup -}]). The generation rates of N{sub 2}, N{sub 2}O, and O{sub 2} are not dependent on the [NO{sub 3}{sup -}] in this narrow range, but are dependent on the presence of HSA and the concentration of HAN. The percentage [H{sub 2}] for the 2.5 to 3.0M NO{sub 3}{sup -} range expected in the off- from the FB-Line Pu{sup +3} Hold Tanks is conservatively estimated to be about 3.5 to 4.5 % for Pu + 3 solutions initially containing 0.023M HAN/0.165M HSA. The upper limit [H{sub 2}] may actually be about 4.1 % (4.3 % at 90 % confidence limits) but more {open_quotes}initial{close_quotes} off-gas rate data is needed at about 2.9M [NO{sub 3}{sup -}] in Pu{sup +3} solution for verification. Addition of ascorbic acid had no effect on the off-gas rate of Pu{sup +3} solutions containing HSA and NO{sub 3}{sup -} concentrations higher than those expected in the hold tanks. The maximum {open_quotes}hold time{close_quotes} for 50 grams/liter Pu{sup +3}/0.165M HSA/0.023M HAN/2.5-3.0M HNO{sub 3} solution is 20.3{+-}2.1 days. After this time the HSA initially present will become exhausted and the [H{sub 2}] will increase to 35 %. This hold time may be longer in [NO{sub 3}{sup -}] < 3.0M, but again more study is needed.

Smith, J.R.

1994-10-28

50

Process for the removal of acid forming gases from exhaust gases  

DOEpatents

Exhaust gases are treated to remove NO or NO[sub x] and SO[sub 2] by contacting the gases with an aqueous emulsion or suspension of yellow phosphorus preferably in a wet scrubber. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50 C is attractive. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO[sub x] and SO[sub 2], alkalis that are used for flue gas desulfurization are preferred. With this process, 100% of the by-products created are usable, and close to 100% of the NO or NO[sub x] and SO[sub 2] can be removed in an economic fashion. 9 figs.

Chang, S.G.; Liu, D.K.

1992-11-17

51

Process for the removal of acid forming gases from exhaust gases  

DOEpatents

Exhaust gases are treated to remove NO or NO.sub.x and SO.sub.2 by contacting the gases with an aqueous emulsion or suspension of yellow phosphorus preferably in a wet scrubber. The pressure is not critical, and ambient pressures are used. Hot water temperatures are best, but economics suggest about 50.degree. C. are attractive. The amount of yellow phosphorus used will vary with the composition of the exhaust gas, less than 3% for small concentrations of NO, and 10% or higher for concentrations above say 1000 ppm. Similarly, the pH will vary with the composition being treated, and it is adjusted with a suitable alkali. For mixtures of NO.sub.x and SO.sub.2, alkalis that are used for flue gas desulfurization are preferred. With this process, 100% of the by-products created are usable, and close to 100% of the NO or NO and SO.sub.2 can be removed in an economic fashion.

Chang, Shih-Ger (El Cerrito, CA); Liu, David K. (San Pablo, CA)

1992-01-01

52

Nitrogen, Carbon, and Noble Gases in Apollo Lunar Samples  

NASA Astrophysics Data System (ADS)

A suite of five powdered lunar basalt samples have been analysed for nitrogen, carbon, helium, neon, and argon, using a high-sensitivity stepped combustion mass spectrometer system at the Open University, UK. Preliminary results indicate the presence of cosmogenic nitrogen and carbon, released in small amounts at high temperatures, as well as small amounts of cosmogenic neon and argon (mixed with a trapped non-cosmogenic component). Low temperature steps are dominated by contamination release, although 15555 displays an unusually abundant, isotopically light carbon component, released at 500 °C.

Mortimer, J.; Verchovsky, A. B.; Anand, M.

2013-09-01

53

Carbon, nitrogen and Greenhouse gases budgets over a four years crop rotation in northern France  

Microsoft Academic Search

Croplands mainly act as net sources of the greenhouse gases carbon dioxide (CO2) and nitrous oxide (N2O), as well as nitrogen oxide (NO), a precursor of troposheric ozone. We determined the carbon (C) and nitrogen (N) balance\\u000a of a four-year crop rotation, including maize, wheat, barley and mustard, to provide a base for exploring mitigation options\\u000a of net emissions. The

Benjamin Loubet; Patricia Laville; Simon Lehuger; Eric Larmanou; Christophe Fléchard; Nicolas Mascher; Sophie Genermont; Romain Roche; Rossana M. Ferrara; Patrick Stella; Erwan Personne; Brigitte Durand; Céline Decuq; Dominique Flura; Sylvie Masson; Olivier Fanucci; Jean-Noël Rampon; Jan Siemens; Reimo Kindler; Benoit Gabrielle; Marion Schrumpf; Pierre Cellier

2011-01-01

54

Peatlands, carbon storage, greenhouse gases, and the Kyoto Protocol: Prospects and significance for Canada  

Microsoft Academic Search

The Kyoto Protocol accepts terrestrial sinks for greenhouse gases (GHGs) as offsets for fossil fuel emissions. Only carbon\\u000a sequestered in living biomass from re- and afforestation is presently considered, but the Protocol contains a provision for\\u000a the possible future inclusion of other land uses and soils. As a result, the possibility of sequestration of carbon in wetlands,\\u000a and particularly peatlands,

Nigel T. Roulet

2000-01-01

55

Importance of greenhouse gases other than carbon dioxide and other possible differences between various fuels.  

National Technical Information Service (NTIS)

An attempt has been made to assess factors that indicate how various fuels affect the climate. In these factors emissions of carbon dioxide, methane and nitrous oxide are weighed together with reference to the direct and indirect effects of these gases on...

T. Levander

1989-01-01

56

Atmospheric Trace Gases, Carbon Isotopes, Radionuclides, and Aerosols: Isotopes in Greenhouse Gases Data from the Carbon Dioxide Information Analysis Center (CDIAC)  

DOE Data Explorer

(Scroll down to find Isotopes in Greenhouse Gases, a subheading under the broader heading of Atmospheric Trace Gases, etc.) CDIAC products are indexed and searchable through a customized interface powered by ORNL's Mercury search engine. Products include numeric data packages, publications, trend data, atlases, models, etc. and can be searched for by subject area, keywords, authors, product numbers, time periods, collection sites, spatial references, etc. Some of the collections may also be included in the CDIAC publication Trends Online: A Compendium of Global Change Data. Most data sets, many with numerous data files, are free to download from CDIAC's ftp area. Information related to isotopes in greenhouse gases includes: • Monthly atmospheric 13C/12C isotopic ratios for 10 SIO stations, (2005) (Trends Online) • Mixing ratios of CO, CO2, CH4, and isotope ratios of associated 13C, 18O, and 2H in air samples from Niwot Ridge, Colorado, and Monta±a de Oro, California, USA (2004) • Estimates of Monthly CO2 Emissions and Associated 13C/12C Values from Fossil-Fuel Consumption in the U.S.A., (2004) (Trends Online) ?13C in CO2 from the CSIRO GASLAB Flask Sampling Network (Trends Online) • In Situ 13CO2 from Cape Grim, Tasmania, Australia: 1982-1993 (2001) (Trends Online) • In situ Carbon 13 and Oxygen 18 Ratios of Atmospheric CO2 from Cape Grim, Tasmania, Australia: 1982-1993 (1995) • Carbon-13 Isotopic Abundance and concentration of Atmospheric Methane for Background Air in the Southern and Northern Hemispheres from 1978 to 1989 (1995) • Measurements of Atmospheric Methane and 13C/12C of Atmospheric Methane from Flask Air Samples (1999) • 14CO 2 Observations from Schauinsland, Germany (1997) (Trends Online) • Carbon-14 Measurements in Atmospheric CO 2 from Northern and Southern Hemisphere Sites, 1962-1992 (1996) • Carbon-14 Measurements in Surface Water CO2 from the Atlantic, Indian and Pacific Oceans, 1965-1994 (1998) (Specialized Interface)

57

Ionic Liquids as Catalysts for Sulfuric Acid Production and Cleaning of Flue Gases  

Microsoft Academic Search

\\u000a The present paper is concerned with catalytic pollution abatement of sulfur and nitrogen oxides in flue gases from industrial\\u000a sources. Especially fundamental and applied research on industrial catalysts and their model systems is presented with regards\\u000a to cleaning of flue gases from fossil fuel based power plants and plants producing sulfuric acid. Combined DeSOx and DeNOx processes are very common

Rasmus Fehrmann; K. M. Eriksen; S. B. Rasmussen; J. Winnick

58

Sorption of noble gases by solids, with reference to meteorites. II - Chromite and carbon. III - Sulfides, spinels, and other substances; on the origin of planetary gases  

NASA Astrophysics Data System (ADS)

The trapping of noble gases by chromite and carbon, two putative carriers of primordial noble gases in meteorites, was studied by synthesizing 19 samples in a Ne-Ar-Kr-Xe atmosphere at 440-720 K. Noble gas contents are found to approximately obey Henry's Law, but only slight correlations are found with composition, surface area, or adsorption temperature. Geometric mean distribution coefficients for bulk samples and HCl residues in 10 cu cm STP/g atm are: Xe 100, Kr 15, Ar 3.5, and Ne 0.62. Elemental fractionation data support the suggestion of Lewis et al. (1977) that chromite and carbon in C2 and C3 chondrites were formed by the reaction: Fe, Cr + 4CO yields (Fe, Cr)3O4 + 4C + carbides. In contrast to meteoritic minerals, the synthetic specimens show no isotopic fractionation of noble gases. In a subsequent study, attention is given to the cases of sulfides and spinels, on the way to consideration of the origin of planetary gases. Sulfides showed three distinctive trends relative to chromite or magnetite. The elemental fractionation pattern of Ar, Kr and Xe in meteorites, terrestrial rocks and planets resembles the adsorption patterns on the carbons, spinels, sulfides, and other solids studied. The high release temperature of meteoritic noble gases may be explained by transformation of the physisorbed or chemisorbed gas. The ready loss of meteoritic heavy gases on surficial oxidation is consistent with adsorption, as is the high abundance.

Yang, J.; Anders, E.

1982-06-01

59

Solubilities of Acid Gases and Nitrogen in Methanol.  

National Technical Information Service (NTIS)

The report describes a thermodynamic model, developed to predict the equilibrium behavior of carbon dioxide, hydrogen sulfide, nitrogen, and methanol mixtures. The model uses the four-suffix Margules equation to describe liquid-phase nonidealities and the...

J. K. Ferrell J. N. Matange R. W. Rousseau

1980-01-01

60

ARM Carbon Cycle Gases Flasks at SGP Site  

DOE Data Explorer

Data from flasks are sampled at the Atmospheric Radiation Measurement Program ARM, Southern Great Plains Site and analyzed by the National Oceanic and Atmospheric Administration NOAA, Earth System Research Laboratory ESRL. The SGP site is included in the NOAA Cooperative Global Air Sampling Network. The surface samples are collected from a 60 m tower at the ARM SGP Central Facility, usually once per week in the afternoon. The aircraft samples are collected approximately weekly from a chartered aircraft, and the collection flight path is centered over the tower where the surface samples are collected. The samples are collected by the ARM and LBNL Carbon Project.

Sebastien Biraud

61

ARM Carbon Cycle Gases Flasks at SGP Site  

SciTech Connect

Data from flasks are sampled at the Atmospheric Radiation Measurement Program ARM, Southern Great Plains Site and analyzed by the National Oceanic and Atmospheric Administration NOAA, Earth System Research Laboratory ESRL. The SGP site is included in the NOAA Cooperative Global Air Sampling Network. The surface samples are collected from a 60 m tower at the ARM SGP Central Facility, usually once per week in the afternoon. The aircraft samples are collected approximately weekly from a chartered aircraft, and the collection flight path is centered over the tower where the surface samples are collected. The samples are collected by the ARM and LBNL Carbon Project.

Sebastien Biraud

2013-03-26

62

Parametric study of ReaxFF simulation parameters for molecular dynamics modeling of reactive carbon gases  

NASA Astrophysics Data System (ADS)

The development of innovative carbon-based materials can be greatly facilitated by molecular modeling techniques. Although the Reax Force Field (ReaxFF) can be used to simulate the chemical behavior of carbon-based systems, the simulation settings required for accurate predictions have not been fully explored. Using the ReaxFF, molecular dynamics (MD) simulations are used to simulate the chemical behavior of pure carbon and hydrocarbon reactive gases that are involved in the formation of carbon structures such as graphite, buckyballs, amorphous carbon, and carbon nanotubes. It is determined that the maximum simulation time step that can be used in MD simulations with the ReaxFF is dependent on the simulated temperature and selected parameter set, as are the predicted reaction rates. It is also determined that different carbon-based reactive gases react at different rates, and that the predicted equilibrium structures are generally the same for the different ReaxFF parameter sets, except in the case of the predicted formation of large graphitic structures with the Chenoweth parameter set under specific conditions.

Jensen, Benjamin D.

63

Gallic acid water ozonation using activated carbon  

Microsoft Academic Search

The ozonation of gallic acid in water in the presence of activated carbon has been studied at pH 5. Hydrogen peroxide, ketomalonic and oxalic acids were identified as by-products. The process involves two main periods of reaction. The first period, up to complete disappearance of gallic acid, during which ozonation rates are slightly improved by the presence of activated carbon.

Fernando J. Beltrán; Juan F. García-Araya; Inés Giráldez

2006-01-01

64

SOLUBILITIES OF ACID GASES AND NITROGEN IN METHANOL  

EPA Science Inventory

The report describes a thermodynamic model, developed to predict the equilibrium behavior of carbon dioxide, hydrogen sulfide, nitrogen, and methanol mixtures. The model uses the four-suffix Margules equation to describe liquid-phase nonidealities and the Soave modification of th...

65

Molecular equilibria and condensation sequences in carbon rich gases  

NASA Technical Reports Server (NTRS)

Chemical equilibria in stellar atmospheres have been investigated by many authors. Lattimer, Schramm, and Grossman presented calculations in both O rich and C rich environments and predicted possible presolar condensates. A recent paper by Cherchneff and Barker considered a C rich composition with PAH's included in the calculations. However, the condensation sequences of C bearing species have not been investigated in detail. In a carbon rich gas surrounding an AGB star, it is often assumed that graphite (or diamond) condenses out before TiC and SiC. However, Lattimer et al. found some conditions under which TiC condenses before graphite. We have performed molecular equilibrium calculations to establish the stability fields of C(s), TiC(s), and SiC(s) and other high temperature phases under conditions of different pressures and C/O. The preserved presolar interstellar dust grains so far discovered in meteorites are graphite, diamond, SiC, TiC, and possibly Al2O3.

Sharp, C. M.; Wasserburg, G. J.

1993-01-01

66

Flame Synthesis of Carbon Nanotubes Using Low Calorific Value Gases  

SciTech Connect

Nanostructures formed in diffusion flames of pure fuels [CH{sub 4}, C{sub 3}H{sub 8}, and C{sub 2}H{sub 2}] at different fuel flow rates have been analyzed. Synthesis samples have been also collected from diffusion flames of various fuel blends [H{sub 2}-CH{sub 4}, H{sub 2}-CO, H{sub 2}-C{sub 3}H{sub 8}, H{sub 2}-C{sub 2}H{sub 2}] at different combustion conditions. SEM images of particulate samples collected from H{sub 2}-CH{sub 4} diffusion flames show formation of nanostructures. However, the formation of nanostructures only occurs at a narrow window of fuel compositions (< 10% H{sub 2} concentration in the mixture) and flow conditions (Jet Exit Reynolds number Re{sub j} = 200). At higher H{sub 2} concentration and flow velocity, formation of nanostructures diminishes and H{sub 2}-CH{sub 4} flames produce amorphous carbon and soot particles.

Jorge Camacho; Mahesh Subramanya; Ahsan R. Choudhuri

2007-03-31

67

Carbon dioxide sequestration by direct mineral carbonation with carbonic acid  

SciTech Connect

The Albany Research Center (ARC) of the U.S. Dept. of Energy (DOE) has been conducting a series of mineral carbonation tests at its Albany, Oregon, facility over the past 2 years as part of a Mineral Carbonation Study Program within the DOE. Other participants in this Program include the Los Alamos National Laboratory, Arizona State University, Science Applications International Corporation, and the DOE National Energy Technology Laboratory. The ARC tests have focused on ex-situ mineral carbonation in an aqueous system. The process developed at ARC utilizes a slurry of water mixed with a magnesium silicate mineral, olivine [forsterite end member (Mg2SiO4)], or serpentine [Mg3Si2O5(OH)4]. This slurry is reacted with supercritical carbon dioxide (CO2) to produce magnesite (MgCO3). The CO2 is dissolved in water to form carbonic acid (H2CO3), which dissociates to H+ and HCO3 -. The H+ reacts with the mineral, liberating Mg2+ cations which react with the bicarbonate to form the solid carbonate. The process is designed to simulate the natural serpentinization reaction of ultramafic minerals, and for this reason, these results may also be applicable to in-situ geological sequestration regimes. Results of the baseline tests, conducted on ground products of the natural minerals, have been encouraging. Tests conducted at ambient temperature (22 C) and subcritical CO2 pressures (below 73 atm) resulted in very slow conversion to the carbonate. However, when elevated temperatures and pressures are utilized, coupled with continuous stirring of the slurry and gas dispersion within the water column, significant reaction occurs within much shorter reaction times. Extent of reaction, as measured by the stoichiometric conversion of the silicate mineral (olivine) to the carbonate, is roughly 90% within 24 hours, using distilled water, and a reaction temperature of 185?C and a partial pressure of CO2 (PCO2) of 115 atm. Recent tests using a bicarbonate solution, under identical reaction conditions, have achieved roughly 83% conversion of heat treated serpentine and 84% conversion of olivine to the carbonate in 6 hours. The results from the current studies suggest that reaction kinetics can be improved by pretreatment of the mineral, catalysis of the reaction, or some combination of the two. Future tests are intended to examine a broader pressure/temperature regime, various pretreatment options, as well as other mineral groups.

O'Connor, William K.; Dahlin, David C.; Nilsen, David N.; Walters, Richard P.; Turner, Paul C.

2000-01-01

68

Control of Effluent Gases from Solid Waste Processing Using Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

One of the major problems associated with solid waste processing technologies is the release of effluent gases and contaminants that are in gaseous formed from the processes. A number of other gases, in particular NO(x), SO2, NH3, Hydrocarbons (e.g. CH4) do present hazards to the crew in space habitats. Reduction of mass, power, volume and resupply can be achieved by using catalyst impregnated carbon nanotubes as compared to other catalytic systems. The development and characterization of an innovative approach for the control and elimination of gaseous toxins using single walled carbon nanotubes (SWNTs) promise superior performance over conventional approaches. This is due to the ability to direct the selective uptake of gaseous species based on their controllable pore size, high adsorptive capacity and the effectiveness of carbon nanotubes as catalyst supports for gaseous conversion. For example, SWNTs have high adsorptive capacity for NO and the adsorbed NO can be decomposed to N2 and O2 . Experimental results showing the decomposition of NO on metal impregnated carbon nanotubes is presented. Equivalent System Mass (ESM) comparisons are made of the existing TCCS systems with the carbon nanotube technology for removing NO(x). The potential for methane decomposition using carbon nanotubes catalysts is also discussed.

Fisher, John; Cinke, Martin; Wignarajab, Kanapathipillai

2005-01-01

69

Adsorption behavior of ternary mixtures of noble gases inside single-walled carbon nanotube bundles  

NASA Astrophysics Data System (ADS)

In order to study the gas-storage and gas-filtering capability of carbon nanotube (CNT) bundles simultaneously, we considered the adsorption behavior of a ternary mixture of noble gases, including Argon (Ar), Krypton (Kr), and Xenon (Xe), i.e., Ar-Kr-Xe mixture, on (10, 10) single-walled carbon nanotube (SWCNT) bundles. Molecular dynamics (MD) simulations at different temperatures of (75, 100, 150, 200, 250, and 300) K were performed, and adsorption energies, self-diffusion coefficients, activation energies, and radial distribution functions (RDFs) were computed to analyze the thermodynamics, transport and structural properties of the adsorption systems. It is observed that the SWCNT bundles have larger contents of heavier noble gases compared to the lighter ones. This interesting behavior of SWCNT bundles makes them proper candidates for gas-storage and gas molecular-sieving processes.

Foroutan, Masumeh; Nasrabadi, Amir Taghavi

2010-09-01

70

Method and apparatus for separating gases based on electrically and magnetically enhanced monolithic carbon fiber composite sorbents  

DOEpatents

A method for separating gases or other fluids involves placing a magnetic field on a monolithic carbon fiber composite sorption material to more preferentially attract certain gases or other fluids to the sorption material to which a magnetic field is applied. This technique may be combined with the known "pressure swing adsorption" technique utilizing the same sorption material.

Judkins, Roddie R. (9917 Rainbow Dr., Knoxville, TN 37922); Burchell, Timothy D. (109 Greywood Pl., Oak Ridge, TN 37830)

1999-01-01

71

Method and apparatus for separating gases based on electrically and magnetically enhanced monolithic carbon fiber composite sorbents  

DOEpatents

A method for separating gases or other fluids involves placing a magnetic field on a monolithic carbon fiber composite sorption material to more preferentially attract certain gases or other fluids to the sorption material to which a magnetic field is applied. This technique may be combined with the known pressure swing adsorption'' technique utilizing the same sorption material. 1 fig.

Judkins, R.R.; Burchell, T.D.

1999-07-20

72

Acid sorption regeneration process using carbon dioxide  

DOEpatents

Carboxylic acids are sorbed from aqueous feedstocks onto a solid adsorbent in the presence of carbon dioxide under pressure. The acids are freed from the sorbent phase by a suitable regeneration method, one of which is treating them with an organic alkylamine solution thus forming an alkylamine-carboxylic acid complex which thermally decomposes to the desired carboxylic acid and the alkylamine.

King, C. Judson (Kensington, CA); Husson, Scott M. (Anderson, SC)

2001-01-01

73

Emission factors for particles, elemental carbon, and trace gases from the Kuwait oil fires  

SciTech Connect

Emission factors are presented for particles, elemental carbon (i.e., soot), total organic carbon in particles and vapor, and for various trace gases from the 1991 Kuwait oil fires. Particle emissions accounted for {approximately} 2% of the fuel burned. In general, soot emission factors were substantially lower than those used in recent {open_quotes}nuclear winter{close_quotes} calculations. Differences in the emissions and appearances of some of the individual fires are discussed. Carbon budget data for the composite plumes from the Kuwait fires are summarized; most of the burned carbon in the plumes was in the form of CO{sub 2}. Fluxes are presented for several combustion products. 26 refs., 1 fig., 5 tabs.

Laursen, K.K.; Ferek, R.J.; Hobbs, P.V. [Univ. of Washington, Seattle, WA (United States); Rasmussen, R.A. [Oregon Graduate Institute of Science and Technology, Beaverton, OR (United States)

1992-09-20

74

Origins of natural gases from marine strata in Northeastern Sichuan Basin (China) from carbon molecular moieties and isotopic data  

NASA Astrophysics Data System (ADS)

To determine the origin, maturity, formation mechanism and secondary process of marine natural gases in Northeastern Sichuan area, molecular moieties and carbon isotopic data of the Carboniferous and Triassic gases have been analyzed. Typical samples of marine gas precursors including low-maturity kerogen, dispersed liquid hydrocarbons (DLHs) in source rocks, residual kerogen and oil have been examined in a closed system, and several published geochemical diagrams of gas origins have been calibrated by using laboratory data. Results show that both Carboniferous and Triassic gases in the study area have a thermogenic origin. Migration leads to stronger compositional and weak isotopic fractionation, and is path dependent. Carboniferous gases and low-H2S gases are mainly formed by secondary cracking of oil, whereas high-H2S gases are clearly related to the TSR (Thermal Sulfate Reduction) process. Gases in NE Sichuan show a mixture of heavy (13C-enriched) methane in comparison to the lower maturated ethane of Triassic gas samples, suggesting a similar source and maturity for ethane and propane of Carboniferous gases, and a mixture of heavy ethane to the propane for Triassic gases. Based on the data plotted in the diagram of Chung et al. (1988), the residual kerogen from Silurian marine shale and palaeo oil reservoirs are the main source for Carboniferous gases, and that the residual kerogen from Silurian and Permian marine rocks and Permian paleao oil reservoirs constitute the principal source of Triassic gases.

Wang, Yunpeng; Zhao, Changyi; Wang, Hongjun; Wang, Zhaoyun; Wang, Zecheng

2013-03-01

75

Indoor and outdoor concentrations of inorganic acidic aerosols and gases  

SciTech Connect

Annular denuder-filter pack sampling systems were used to make indoor and outdoor measurements of aerosol strong H{sup +}, SO{sub 4}{sup 2{minus}}, NH{sub 4}{sup +}, NO{sub 3}{sup {minus}} and NO{sub 2}{sup {minus}}, and the gaseous pollutants SO{sub 2}, HNO{sub 3}, HONO and NH{sub 3} during summer and winter periods in Boston, Massachusetts. Outdoor levels of SO{sub 2}, HNO{sub 3}, H{sup +} and SO{sub 4}{sup 2{minus}} exceeded their indoor concentrations during both seasons. Winter indoor/outdoor ratios were lower than during the summer, probably due to lower air exchange rates during the winter period. During both monitoring periods, indoor/outdoor ratios of aerosol strong H{sub +} were 40-50% of the indoor/outdoor SO{sub 4}{sup 2{minus}} ratio. Since aerosol strong acidity is typically associated with SO{sub 4}{sup 2{minus}}, this finding is indicative of neutralization of the acidic aerosol by the higher indoor NH{sub 3} levels. Geometric mean indoor/outdoor NH{sub 3} ratios of 3.5 and 23 respectively were measured for the summer and winter sampling periods. For HONO, NH{sub 3}, NH{sub 4}{sup +} and NO{sub 2}{sup {minus}}, indoor concentrations were significantly higher than ambient levels. Indoor levels of NO{sub 3}{sup {minus}} were slightly less than outdoor concentrations.

Brauer, M.; Koutrakis, P.; Keeler, G.J.; Spengler, J.D. (Harvard Univ., Boston, MA (USA))

1991-02-01

76

Carbon isotope systematics of CO2, CO and CH4 in fumarolic gases from Satsuma-Iwojima volcanic island, Japan  

Microsoft Academic Search

Carbon isotopic composition (d13C) of CO2, CO and CH4 were determined for fumarolic gases from Satsuma-Iwojima, to range from -3.1 to -2.6°, from -11.6 to -2.8° and from -56 to -37°, respectively. Carbon isotope exchange equilibrium temperature between CO2 and CO was calculated to be ranging from 896° to 950°C for high temperature (691° to 882°C) fumarolic gases, suggesting that

Masanori Sato; Toshiya Mori; Yoichi Shimoike; Keisuke Nagao; Kenji Notsu

2002-01-01

77

Controlled Confinement and Release of Gases in Single-Walled Carbon Nanotube Bundles  

NASA Astrophysics Data System (ADS)

A simple procedure is described which locks small quantities of SF6, CO2, and ^13CO2 into opened single-walled carbon nanotube (SWNT) bundles and keeps the gas inside the SWNTs above the desorption temperature of these molecules. The confinement technique involves opening the SWNTs with ozonolysis at 300 K followed by vacuum annealing at 700 K. Gases are then cryogenically adsorbed into the opened SWNTs and a locked into the SWNT pores by functionalizing the sample with a low temperature ozone treatment. The low temperature ozone treatment functionalizes the entry ports into the SWNT pores which in turn create a physical barrier for gases trying to desorb through these functionalized ports. The samples are stable under vacuum for periods of at least 24 hours and the trapped gases can be released by vacuum heating to 700 K. Reduced quantities of the trapped gases remain in the SWNTs even after exposure to room air. Fourier Transform Infrared Spectroscopy is used to monitor the functionalities resulting from the ozone treatment and to detect the trapped gas species.

Matranga, Christopher; Bockrath, Bradley

2006-03-01

78

Control of Effluent Gases from Solid Waste Processing using Impregnated Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

One of the major problems associated with solid waste processing technologies is effluent contaminants that are released in gaseous forms from the processes. This is a concern in both biological as well as physicochemical solid waste processing. Carbon dioxide (CO2), the major gas released, does not present a serious problem and there are currently in place a number of flight-qualified technologies for CO2 removal. However, a number of other gases, in particular NOx, SO2, NH3, and various hydrocarbons (e.g. CH4) do present health hazards to the crew members in space habitats. In the present configuration of solid waste processing in the International Space Station (ISS), some of these gases are removed by the Trace Contaminant Control System (TCCS), demands a major resupply. Reduction of the resupply can be effective by using catalyst impregnated carbon nanotubes. For example, NO decomposition to N2 and O2 is thermodynamically favored. Data showing decomposition of NO on metal impregnated carbon nanotubes is presented. Comparisons are made of the existing TCCS systems with the carbon nanotube based technology for removing NOx based on mass/energy penalties.

Li, Jing; Fisher, John; Wignarajah, Kanapathipillai

2005-01-01

79

High emissions of carbon gases from a boreal headwater stream network of Interior Alaska  

NASA Astrophysics Data System (ADS)

Small boreal streams integrate the signals of terrestrial and aquatic carbon cycling in their catchments. Recent evidence suggests that despite their limited coverage on the landscape, small streams play a significant role in the downstream delivery of carbon and the emission of trace carbon gases (methane and carbon dioxide) to the atmosphere. However, aquatic gas emissions have not been well documented in many parts of the boreal forest including interior Alaska. We measured carbon gas emissions from a headwater stream network in the Beaver Creek watershed, Yukon River basin, during May (spring thaw) to September, 2011 using discrete measurements and continuous monitoring of stream pCO2. Carbon dioxide emissions from all sites averaged >4.5 gC m-2 day-1, with small streams exhibiting the highest and most variable emission rates. All sites were supersaturated with CO2 for the entire open-water season. Methane emissions averaged >9.1 mgC m-2 day-1 with a maximum of ~37 mgC m-2 day-1 in a mostly burned catchment. Low water temperatures and short water residence times probably limit in-stream respiration and support the hypothesis that high pCO2 in these streams is derived from terrestrial respiration and groundwater sources. Lower pCO2 of larger streams is likely controlled by rapid outgassing in upstream reaches and poor hydrologic connectivity with portions of the surrounding landscape. Overall, these small upland streams are a constant source of trace gases to the atmosphere during the ice free season and exhibit much higher emission rates than most previously studied boreal stream networks. This reinforces the need for more complete characterization of the spatial and temporal patterns of stream C-gas emissions when assessing whole watershed carbon budgets.

Crawford, J. T.; Striegl, R. G.; Wickland, K. P.; Stanley, E. H.

2011-12-01

80

Modeling of wormhole behavior in carbonate acidizing  

SciTech Connect

A mathematical model that describes the growth and competition of wormholes during an acidizing treatment in a carbonate formation is developed. The purpose of the treatment is to remove any near wellbore permeability damage created by drilling or completion fluids so that the production of reservoir fluids is stimulated. Hydrochloric acid is commonly used for this purpose. Since the acid solution tends to flow into the less resistant areas, large pores on the rock surface receive most acid fluid. Pores are enlarged due to the reaction between acid solution and carbonates. The growth of large pores in the formation is referred to as wormholing. Results from the model show that wormholes are formed due to the heterogeneity of carbonate rock and the reaction kinetics between acid and carbonates. Formation of a dominant wormhole is controlled by fluid diffusivity and fluid loss. Model results have good agreement with the results from published papers.

Hung, K.M.

1987-01-01

81

Automatic Carbon Dioxide-Methane Gas Sensor Based on the Solubility of Gases in Water  

PubMed Central

Biogas methane content is a relevant variable in anaerobic digestion processing where knowledge of process kinetics or an early indicator of digester failure is needed. The contribution of this work is the development of a novel, simple and low cost automatic carbon dioxide-methane gas sensor based on the solubility of gases in water as the precursor of a sensor for biogas quality monitoring. The device described in this work was used for determining the composition of binary mixtures, such as carbon dioxide-methane, in the range of 0–100%. The design and implementation of a digital signal processor and control system into a low-cost Field Programmable Gate Array (FPGA) platform has permitted the successful application of data acquisition, data distribution and digital data processing, making the construction of a standalone carbon dioxide-methane gas sensor possible.

Cadena-Pereda, Raul O.; Rivera-Munoz, Eric M.; Herrera-Ruiz, Gilberto; Gomez-Melendez, Domingo J.; Anaya-Rivera, Ely K.

2012-01-01

82

Automatic carbon dioxide-methane gas sensor based on the solubility of gases in water.  

PubMed

Biogas methane content is a relevant variable in anaerobic digestion processing where knowledge of process kinetics or an early indicator of digester failure is needed. The contribution of this work is the development of a novel, simple and low cost automatic carbon dioxide-methane gas sensor based on the solubility of gases in water as the precursor of a sensor for biogas quality monitoring. The device described in this work was used for determining the composition of binary mixtures, such as carbon dioxide-methane, in the range of 0-100%. The design and implementation of a digital signal processor and control system into a low-cost Field Programmable Gate Array (FPGA) platform has permitted the successful application of data acquisition, data distribution and digital data processing, making the construction of a standalone carbon dioxide-methane gas sensor possible. PMID:23112626

Cadena-Pereda, Raúl O; Rivera-Muñoz, Eric M; Herrera-Ruiz, Gilberto; Gomez-Melendez, Domingo J; Anaya-Rivera, Ely K

2012-01-01

83

Survey of lunar carbon compounds. I - The presence of indigenous gases and hydrolysable carbon compounds in Apollo 11 and Apollo 12 samples  

NASA Technical Reports Server (NTRS)

Indigenous gases and hydrolyzable carbon compounds in Apollo 11 and 12 samples through gas chromatographic and mass spectrometric examination, noting meteoritic impact and solar wind implantation as probable origins

Abell, P. I.; Cadogan, P. H.; Eglinton, G.; Maxwell, J. R.; Pillinger, C. T.

1971-01-01

84

Utilization of carbon dioxide in industrial flue gases for the cultivation of microalga Chlorella sp.  

PubMed

The biomass and lipid productivity of Chlorella sp. MTF-15 cultivated using aeration with flue gases from a coke oven, hot stove or power plant in a steel plant of the China Steel Corporation in Taiwan were investigated. Using the flue gas from the coke oven, hot stove or power plant for cultivation, the microalgal strain obtained a maximum specific growth rate and lipid production of (0.827d(-1), 0.688gL(-1)), (0.762d(-1), 0.961gL(-1)), and (0.728d(-1), 0.792gL(-1)), respectively. This study demonstrated that Chlorella sp. MTF-15 could efficiently utilize the CO2, NOX and SO2 present in the different flue gases. The results also showed that the growth potential, lipid production and fatty acid composition of the microalgal strain were dependent on the composition of the flue gas and on the operating strategy deployed. PMID:24950094

Kao, Chien-Ya; Chen, Tsai-Yu; Chang, Yu-Bin; Chiu, Tzai-Wen; Lin, Hsiun-Yu; Chen, Chun-Da; Chang, Jo-Shu; Lin, Chih-Sheng

2014-08-01

85

Use of calibration gases in the U.S. acid rain program  

Microsoft Academic Search

The United States Acid Rain Program continuous emission monitors (CEMs) have been successful in producing quality-assured\\u000a data 95% of the time, and in meeting a relative accuracy standard of less than or equal to 10.0% at over 99% of the CEMs in\\u000a the program. One key reason for this high accuracy is the required use of high quality calibration gases

J. T. Schakenbach

2001-01-01

86

Design of packed, adiabatic absorbers: Physical absorption of acid gases in methanol  

Microsoft Academic Search

An algorithm was developed to calculate concentration and temperature profiles for an adiabatic, packed absorber. Calculations performed with this algorithm compared favorably with data obtained on a pilot scale absorber having a diameter of 0.127 m (5 in.) and packed with 6.25-mm (0.25 in.) ceramic Intalox saddles. The data were obtained for absorption of acid gases from a stream produced

Robert M. Kelly; J. K. Ferrell; R. W. Rousseau

1984-01-01

87

Soluble species in the Arctic summer troposphere - Acidic gases, aerosols, and precipitation  

NASA Technical Reports Server (NTRS)

The large-scale spatial distribution from 0.15-to 6 km altitude in the North American Arctic troposphere of several soluble acidic gases and major aerosol species during the summertime is reported. The distribution is found to be compositionally consistent on a large spatial scale. The summertime troposphere is an acidic environment, with HCOOH and CH3COOH the principal acidic gases while acidic sulfate aerosols dominate the particulate phase. There appears to be a surface source of NH3 over the pack ice which may originate from decay of dead marine organisms on the ice surface, evolution from surface ocean waters in open ice leads, or release from rotting sea ice. At low altitude over the pack ice this NH34 appears to partially neutralize aerosol acidity. Over sub-Arctic tundra in southeastern Alaska, inputs of marine biogenic sulfur from the Bering Sea appear to be an important source of boundary layer aerosol SO4(2-). The rainwater acidity over the tundra is typical of remote regions.

Talbot, R. W.; Vijgen, A. S.; Harriss, R. C.

1992-01-01

88

Impact of carbon dioxide, trace gases, and climate change on global agriculture  

SciTech Connect

Global climate change is one of several important issues that will command the attention of policymakers and scientist in the 1990s. The evidence that concentrations of carbon dioxide (CO{sub 2}), and other gases are increasing in the atmosphere is irrefutable. The evidence, and the knowledge that CO{sub 2} and trace gases may absorb thermal radiation sufficient to warm the atmosphere, has prompted much speculation that ensuing atmospheric warming may lead to changes in the distribution of precipitation, and of crop adaptation and productivity, that would alter the world supply of food and fiber. The implications of this speculation are compelling for agronomists, because agronomists are stewards of the world's food supply and of the natural resources that are used to produce food. Agronomists have a pivotal role in conducting the research needed to anticipate crop response to climate changes, and in informing policymakers and the general public about the adequacy of our knowledge. In this publication agronomists assess the current status of scientific knowledge about the putative role of greenhouse gases in global climate change and report their findings.

Not Available

1990-01-01

89

Analysis of Effluent Gases During the CCVD Growth of Multi Wall Carbon Nanotubes from Acetylene  

NASA Technical Reports Server (NTRS)

Catalytic chemical vapor deposition was used to grow multi-walled carbon nanotubes on a Fe:Co:CaCO3 catalyst from acetylene. The influent and effluent gases were analyzed by gas chromatography and mass spectrometry at different time intervals during the nanotubes growth process in order to better understand and optimize the overall reaction. A large number of byproducts were identified and it was found that the number and the level for some of the carbon byproducts significantly increased over time. The CaCO3 catalytic support thermally decomposed into CaO and CO2 resulting in a mixture of two catalysts for growing the nanotubes, which were found to have outer diameters belonging to two main groups 8 to 35 nm and 40 to 60 nm, respectively.

Schmitt, T. C.; Biris, A. S.; Miller, D. W.; Biris, A. R.; Lupu, D.; Trigwell, S.; Rahman, Z. U.

2005-01-01

90

Biogeochemical cycling of carbon, water, energy, trace gases, and aerosols in Amazonia: The LBA-EUSTACH experiments  

Microsoft Academic Search

The biogeochemical cycling of carbon, water, energy, aerosols, and trace gases in the Amazon Basin was investigated in the project European Studies on Trace Gases and Atmospheric Chemistry as a Contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA-EUSTACH). We present an overview of the design of the project, the measurement sites and methods, and the meteorological conditions during the

M. O. Andreae; P. Artaxo; C. Brandão; F. E. Carswell; P. Ciccioli; A. L. da Costa; A. D. Culf; J. L. Esteves; J. H. C. Gash; J. Grace; P. Kabat; J. Lelieveld; Y. Malhi; A. O. Manzi; F. X. Meixner; A. D. Nobre; C. Nobre; M. d. L. P. Ruivo; M. A. Silva-Dias; P. Stefani; R. Valentini; J. von Jouanne; M. J. Waterloo

2002-01-01

91

Lower mantle contribution to the genesis of carbonatites: the noble gases and carbon isotopic evidence  

NASA Astrophysics Data System (ADS)

It has been demonstrated that only 20 to 40% of the subducted CO2 is extracted by decarbonatation of descending slab. This, and the fact that some carbonatites exhibit HIMU-like Pb, Nd and Sr isotopic signatures, led to models invoking a carbonatite origin by partial melting of ancient subducted carbonated oceanic crust. A recycled carbon origin for diamonds has also been suggested. However the mantle is the largest carbon reservoir of the Earth and a non-recycled (i.e. primordial) origin for the carbon in carbonatites cannot be discarded. Some of the Cape Verde oceanic carbonatites present low 4He/3He ratios (down to 46,700; R/Ra up to 15.5) demonstrating that they sample a reservoir characterized by low time-integrated (U+Th)/3He. Such a reservoir, being clearly distinct from the crust or from the upper mantle sampled by the 60 000 km long oceanic ridge system, is thought to be localized in the lower mantle. For continental carbonatites several authors has also interpreted noble gases isotopic compositions as reflecting the contribution of a reservoir with time-integrated (U+Th)/(3He, 22Ne) and 40K/36Ar lower than the upper mantle, thus endorsing the contribution of the lower mantle [1;2;3]. Some carbonatites are also characterized by 129Xe anomalies relatively to the air (129Xe/130Xe up to 6.94 in Cape Verde). Considering that the recycling of carbonates, eventually characterized by high Te and Ba contents, would with time increase simultaneously the 129Xe and 130Xe, the observed 129Xe anomalies cannot be explained by models calling upon crustal carbonate recycling. We interpret them in terms of an ancient mantle origin by decay of the now extinct 129I. Moreover, experimental work has demonstrated that crustal carbonates are unlikely to be transported to lower mantle depth levels as a consequence of its removal by melting reactions. Thus, all the above described lower mantle signals are indicative of a non-recycled, lower mantle, origin for carbon, unless we admit that, during ascent, deep-seated mantle plumes entrain recycled carbon from the upper mantle. Nevertheless many carbonatites are also characterized by ^13C values (-8.0 to -4.25 per mil in Cape Verde) lighter than those characterizing crustal inorganic carbonates, endorsing the role of primordial carbon to the genesis of carbonatites. Taking into account that a recycled origin for some carbonatites is inescapable from carbon and noble gases signatures [e.g. 4; 5] we conclude that multiple origins (recycled vs. primordial) are possible for the carbon involved in the generation of carbonatitic magmas. Sasada et al. (1997) - Geochim. Cosmochim. Acta, 61: 4219-4228 Marty et al. (1998)- Earth Planet. Sci. Lett., 164: 179-192 Tolstikhin et al. (2002) - Geochim. Cosmochim. Acta, 66: 881-901 Ray et al. (1999) - Earth Planet Sci. Lett., 170; 205-214 Basu & Murty (2006) - Chem. Geol., 234: 236-250 This is a contribution from the FCT/FEDER project PLINT (POCTI/CTA/45802/2002)

Mata, J.; Moreira, M.; Mourão, C.; Ader, M.; Doucelance, R.

2009-04-01

92

Combustion systems and power plants incorporating parallel carbon dioxide capture and sweep-based membrane separation units to remove carbon dioxide from combustion gases  

DOEpatents

Disclosed herein are combustion systems and power plants that incorporate sweep-based membrane separation units to remove carbon dioxide from combustion gases. In its most basic embodiment, the invention is a combustion system that includes three discrete units: a combustion unit, a carbon dioxide capture unit, and a sweep-based membrane separation unit. In a preferred embodiment, the invention is a power plant including a combustion unit, a power generation system, a carbon dioxide capture unit, and a sweep-based membrane separation unit. In both of these embodiments, the carbon dioxide capture unit and the sweep-based membrane separation unit are configured to be operated in parallel, by which we mean that each unit is adapted to receive exhaust gases from the combustion unit without such gases first passing through the other unit.

Wijmans, Johannes G. (Menlo Park, CA); Merkel, Timothy C (Menlo Park, CA); Baker, Richard W. (Palo Alto, CA)

2011-10-11

93

Air pollution: sensitive detection of ten pollutant gases by carbon monoxide and carbon dioxide lasers.  

PubMed

Detection sensitivities of a few parts per billion for ten gaseous pollutants have been evaluated by measuring the strength of the absorption of infrared radiation from carbon monoxide and carbon dioxide lasers. Ethylene concentrations as small as 5 parts per billion have been detected in air. The measured absorption strengths indicate that in mixtures of pollutants, such as nitrogen dioxide and water vapor, the sensitivity is reduced by overlapping absorption bands. However, calculations indicate that it should be possible to detect nitrogen dioxide concentrations of 0.01 part per million in the presence of water vapor concentrations of 105 parts per million. PMID:5035485

Kreuzer, L B; Kenyon, N D; Patel, C K

1972-07-28

94

Modeling the simultaneous transport of two acid gases in tertiary amines with reversible reactions  

SciTech Connect

The objective of this work is to develop a model for the simultaneous mass transfer of two acid gases in tertiary amines accompanied by reversible chemical reactions. The model has been applied to the industrially important system of simultaneous absorption or desorption of CO/sub 2/ and H/sub 2/S in aqueous methyldiethanolamine (MDEA). In most applications the treated gas must be virtually free of H/sub 2/S; however, it is often not necessary or economical to remove substantial amounts of CO/sub 2/. Hence, selective removal of H/sub 2/S from gas streams such as natural or synthetic gases which contain CO/sub 2/ is desirable. In this research a film theory model describing the simultaneous diffusion and reversible reaction of two gases into reactive liquid has been used to predict the mass transfer enhancement factors of CO/sub 2/ and H/sub 2/S in aqueous MDEA solutions. The resulting unstable two point boundary value problem has been solved numerically for a range of the dimensionless parameters that characterize an important application for this system. In studying the simultaneous transport of CO/sub 2/ and H/sub 2/S, it is found that the reversibility of the reactions, under certain conditions, causes desorption to take place although absorption would be expected on the basis of overall driving forces. This showed that not only enhancement factors larger but also smaller than unity and even negative values are possible.

Al-Ghawas, H.A.; Sandall, O.C.

1988-10-01

95

Carbon dioxide sequestration by direct mineral carbonation with carbonic acid  

Microsoft Academic Search

The Albany Research Center (ARC) of the U.S. Dept. of Energy (DOE) has been conducting a series of mineral carbonation tests at its Albany, Oregon, facility over the past 2 years as part of a Mineral Carbonation Study Program within the DOE. Other participants in this Program include the Los Alamos National Laboratory, Arizona State University, Science Applications International Corporation,

William K. OConnor; David C. Dahlin; David N. Nilsen; Richard P. Walters; Paul C. Turner

2000-01-01

96

Greenhouse gases, climate change and the transition from coal to low-carbon electricity  

NASA Astrophysics Data System (ADS)

A transition from the global system of coal-based electricity generation to low-greenhouse-gas-emission energy technologies is required to mitigate climate change in the long term. The use of current infrastructure to build this new low-emission system necessitates additional emissions of greenhouse gases, and the coal-based infrastructure will continue to emit substantial amounts of greenhouse gases as it is phased out. Furthermore, ocean thermal inertia delays the climate benefits of emissions reductions. By constructing a quantitative model of energy system transitions that includes life-cycle emissions and the central physics of greenhouse warming, we estimate the global warming expected to occur as a result of build-outs of new energy technologies ranging from 100 GWe to 10 TWe in size and 1-100 yr in duration. We show that rapid deployment of low-emission energy systems can do little to diminish the climate impacts in the first half of this century. Conservation, wind, solar, nuclear power, and possibly carbon capture and storage appear to be able to achieve substantial climate benefits in the second half of this century; however, natural gas cannot.

Myhrvold, N. P.; Caldeira, K.

2012-03-01

97

Estimated flows of gases and carbon within CEEF ecosystem composed of human, crops and goats  

NASA Astrophysics Data System (ADS)

The Closed Ecology Experiment Facilities (CEEF) can be used as a test bed for Controlled Ecological Life Support Systems (CELSS), because technologies developed for the CEEF system facilitate self-sufficient material circulation necessary for long term missions such as Lunar and Mars exploration. In the experiment conducted under closed condition in FY2003, rice and soybeans were cultivated sequentially in two chambers and a chamber, each having a cultivation area of 30 m2 and floor area of 43 m2, inside the Plantation Module with artificial lighting of the CEEF. In the chamber having a cultivation area of 60 m2 and floor area of 65 m2, inside the Plantation Module with natural and artificial lighting, peanuts and safflowers were also cultivated. Stable transplant (or seeding) and harvest of each crop were maintained during a month. Flows of CO2, O2 and carbon to and from the crops were analyzed during the stable cultivation period. Simulated works and stay in the CEEF lasting five days were conducted two times under ventilating condition in FY2003. Gas exchange of human was estimated using heart rate data collected during the experiments and correlation between gas exchange rate and heart rate. Gas exchange rate and carbon balance of female goats were determined using an open-flow measurement system with a gastight chamber. From these results, flows of gases and carbon in the CEEF were discussed.

Tako, Y.; Komatsubara, O.; Honda, G.; Arai, R.; Nitta, K.

98

Foliage plants for indoor removal of the primary combustion gases carbon monoxide and nitrogen dioxide  

NASA Technical Reports Server (NTRS)

Foliage plants were evaluated for their ability to sorb carbon monoxide and nitrogen dioxide, the two primary gases produced during the combustion of fossil fuels and tobacco. The spider plant (Chlorophytum elatum var. vittatum) could sorb 2.86 micrograms CO/sq cm leaf surface in a 6 h photoperiod. The golden pothos (Scindapsus aureus) sorbed 0.98 micrograms CO/sq cm leaf surface in the same time period. In a system with the spider plant, greater than or equal to 99 percent of an initial concentration of 47 ppm NO2 could be removed in 6 h from a void volume of approximately 0.35 cu m. One spider plant potted in a 3.8 liter container can sorb 3300 micrograms CO and effect the removal of 8500 micrograms NO2/hour, recognizing the fact that a significant fraction of NO2 at high concentrations will be lost by surface sorption, dissolving in moisture, etc.

Wolverton, B. C.; Mcdonald, R. C.; Mesick, H. H.

1985-01-01

99

Carbon Dioxide Separation from Flue Gases: A Technological Review Emphasizing Reduction in Greenhouse Gas Emissions  

PubMed Central

Increasing concentrations of greenhouse gases (GHGs) such as CO2 in the atmosphere is a global warming. Human activities are a major cause of increased CO2 concentration in atmosphere, as in recent decade, two-third of greenhouse effect was caused by human activities. Carbon capture and storage (CCS) is a major strategy that can be used to reduce GHGs emission. There are three methods for CCS: pre-combustion capture, oxy-fuel process, and post-combustion capture. Among them, post-combustion capture is the most important one because it offers flexibility and it can be easily added to the operational units. Various technologies are used for CO2 capture, some of them include: absorption, adsorption, cryogenic distillation, and membrane separation. In this paper, various technologies for post-combustion are compared and the best condition for using each technology is identified.

Songolzadeh, Mohammad; Soleimani, Mansooreh; Takht Ravanchi, Maryam; Songolzadeh, Reza

2014-01-01

100

Effect of foams used during carbonate acidizing  

SciTech Connect

Although acidization has been used successfully for many years to increase the productivity of petroleum wells in carbonate formations, demands on the performance and application of the acidizing process are increasing. This paper investigates a method of in-situ foam generation that allows deeper wormhole penetration yet uses less acid than conventional methods. The dissolution patterns were imaged with neutron radiography, which provided an in-depth understanding of the effects of foam and other critical parameters. Results show that foam is effective in promoting efficient stimulation, even at low acid injection rates.

Bernadiner, M.G. (Mechanical Engineering Dept., New York Polytechnic Univ., Brooklyn, NY (United States)); Thompson, K.E. (Michigan Univ., Ann Arbor, MI (United States)); Fogler, H.S. (Michigan Univ., Ann Arbor, MI (United States). Dept. of Chemical Engineering)

1992-11-01

101

Tungstophosphoric and tungstosilicic acids on carbon as acidic catalysts  

Microsoft Academic Search

Tungstophosphoric (TPA) and tungstosilicic acid (TSA) catalysts supported on carbon were studied. They were prepared by equilibrium and incipient wetness impregnation techniques. Solutions of TPA and TSA in 50% v\\/v ethanol–water were used to impregnate carbon at 20°C. The Fourier transform infrared and 31P nuclear magnetic resonance spectroscopies of TPA and TSA supported catalysts dried at 70°C showed that the

Marcelo E Chimienti; Luis R Pizzio; Carmen V Cáceres; Mirta N Blanco

2001-01-01

102

Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases, Fiscal Year 2002 Annual Report  

SciTech Connect

The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has, since its inception in 1982, enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change, including atmospheric concentrations and atmospheric emissions of carbon dioxide (CO{sub 2}) and other radiatively active gases; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea levels.

Cushman, R.M.

2003-08-28

103

Stability of calcium carbonate and magnesium carbonate in rainwater and nitric acid solutions  

Microsoft Academic Search

Carbonation of magnesium and calcium silicates has emerged as an interesting option for long term storage of captured CO2. However, carbonated minerals are not stable in acidic environments. This study was conducted to determine if synthetically carbonated minerals dissolve in acidic rain and release CO2. Synthetic magnesium and calcium carbonates were leached in nitric acid solutions of various acidities, as

Sebastian Teir; Sanni Eloneva; Carl-Johan Fogelholm; Ron Zevenhoven

2006-01-01

104

Sense toxins\\/sewage gases by chemically and biologically functionalized single-walled carbon nanotube sensor based microwave resonator  

Microsoft Academic Search

In this work the complex permittivity and microwave absorption of toxins\\/sewage gases and functionalized single-walled carbon nanotube sensors in a perturbed microwave resonant cavity are studied with the aid of a kinetic model. The results show that the real permittivity decreases and the imaginary permittivity increases with increasing the electron density; however, the real permittivity increases and the imaginary permittivity

S. B. Tooski

2010-01-01

105

Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases Fiscal Year 2000 Annual Report.  

National Technical Information Service (NTIS)

The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an arc...

R. M. Cushman

2001-01-01

106

Oceanic Trace Gases Numeric Data Packages from the Carbon Dioxide Information Analysis Center (CDIAC)  

DOE Data Explorer

CDIAC products include numeric data packages, publications, trend data, atlases, models, etc. and can be searched for by subject area, keywords, authors, product numbers, time periods, collection sites, spatial references, etc. Most data sets or packages, many with numerous data files, are free to download from CDIAC's ftp area. CDIAC lists the following numeric data packages under the broad heading of Oceanic Trace Gases: Carbon Dioxide, Hydrographic, and Chemical Data Obtained during the R/V Ronald H. Brown Repeat Hydrography Cruise in the Atlantic Ocean: CLIVAR CO2 Section A16S_2005 ( 01/11/05 - 022405) • Determination of Carbon Dioxide, Hydrographic, and Chemical Parameters during the R/V Nathaniel B. Palmer Cruise in the Southern Indian Ocean (WOCE Section S04I, 050396 - 070496) • Inorganic Carbon, Nutrient, and Oxygen Data from the R/V Ronald H. Brown Repeat Hydrography Cruise in the Atlantic Ocean: CLIVAR CO2 Section A16N_2003a (060403 – 081103) • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Maurice Ewing Cruise in the Atlantic Ocean (WOCE Section A17, 010494 - 032194) • Global Ocean Data Analysis Project GLODAP: Results and Data • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Knorr Cruises in the North Atlantic Ocean on WOCE Sections AR24 (1102 – 120596) and A24, A20, and A22 (053097 – 090397) • Carbon Dioxide, Hydrographic and Chemical Data Obtained During the Nine R/V Knorr Cruises Comprising the Indian Ocean CO2 Survey (WOCE Sections I8SI9S, I9N, I8NI5E, I3, I5WI4, I7N, I1, I10, and I2; 120 194 – 012296) • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Meteor Cruise 28/1 in the South Atlantic Ocean (WOCE Section A8, 032994 - 051294) • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Knorr Cruise 138-3, -4, and -5 in the South Pacific Ocean (WOCE Sections P6E, P6C, and P6W, 050292 - 073092) • Global Distribution of Total Inorganic Carbon and Total Alkalinity below the deepest winter mixed layer depths • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V John V. Vickers Cruise in the Pacific Ocean (WOCE Section P13, NOAA CGC92 Cruise, 080492 – 102192) • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Hesperides Cruise in the Atlantic Ocean (WOCE Section A5, 071492 - 081592) • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Thomas G. Thompson Cruise in the Pacific Ocean (WOCE Section P10, 100593 – 111093) • The International Intercomparison Exercise of Underway fCO2 Systems during the R/V Meteor Cruise 36/1 in the North Atlantic Ocean • Carbon Dioxide, Hydrographic, and Chemical Data Obtained during the R/V Meteor Cruise 22/5 in the South Atlantic Ocean (WOCE Section A10, Dec. 1992-Jan, 1993) • Carbon Dioxide, Hydrographic, and Chemical Data Obtained in the South Pacific Ocean (WOCE Sections P16A/P17A, P17E/P19S, and P19C, R/V Knorr , Oct. 1992-April 1993) • Surface Water and Atmospheric Underway Carbon Data Obtained During the World Ocean Circulation Experiment Indian Ocean Survey Cruises (R/V Knorr, Dec. 1994 – Jan, 1996) • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Akademik Ioffe Cruise in the South Pacific Ocean (WOCE Section S4P, Feb.-April 1992) • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Thomas Washington Cruise TUNES-1 in the Equatorial Pacific Ocean (WOCE section P17C) • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During the R/V Thomas Washington Cruise TUNES-3 in the Equatorial Pacific Ocean (WOCE section P16C) • Carbon-14 Measurements in Surface Water CO2 from the Atlantic, Indian and Pacific Oceans, 1965-1994 • Carbon Dioxide, Hydrographic, and Chemical Data Obtained During R/V Meteor Cruise 18/1 in the North Atlantic Ocean (WOCE Section A1E) • Carbon Dioxide, Hydrographic, and Chemical Data Obtained in the Central South Pacific Ocean (WOCE Sections P17S and P16S) during the TUNES-2 Expedition of the R

107

SEPARATION OF CO2 FROM FLUE GASES BY CARBON-MULTIWALL CARBON NANOTUBE MEMBRANES  

SciTech Connect

Multiwalled carbon nanotubes (MWNT) were found to be an effective separation media for removing CO{sub 2} from N{sub 2}. The separation mechanism favors the selective condensation of CO{sub 2} from the flowing gas stream. Significant uptakes of CO{sub 2} were measured at 30 C, 150 C and 300 C over the pressure range 0.5 to 5 bar. No measurable uptake of nitrogen was found for this range of conditions. The mass uptake of CO{sub 2} by MWNT was found to increase with increasing temperature. A packed bed of MWNT completely removed CO{sub 2} from a flowing stream of CO{sub 2}/N{sub 2}, and exhibited rapid uptake kinetics for CO{sub 2}.

Rodney Andrews

2001-11-01

108

SEPARATION OF CO2 FROM FLUE GASES BY CARBON-MULTIWALL CARBON NANOTUBE MEMBRANES  

SciTech Connect

Multiwalled carbon nanotubes (MWNT) were found to be an effective separation media for removing CO{sub 2} from N{sub 2}. The separation mechanism favors the selective condensation of CO{sub 2} from the flowing gas stream. Significant uptakes of CO{sub 2} were measured at 30 C and 150 C over the pressure range 0.5 to 5 bar. No measurable uptake of nitrogen was found for this range of conditions. The mass uptake of CO{sub 2} by MWNT was found to increase with increasing temperature. A packed bed of MWNT completely removed CO{sub 2} from a flowing stream of CO{sub 2}/N{sub 2}, and exhibited rapid uptake kinetics for CO{sub 2}.

Rodney Andrews

2001-03-01

109

Carbon Steel from Prereduced Pellets: Acid Practice.  

National Technical Information Service (NTIS)

Eleven steelmaking heats are described in which acid practice was used to produce carbon steel from prereduced iron ore pellets. Lime was added to the furnace charge at two levels to eight of the heats to modify slag characteristics in the furnace and to ...

W. L. Hunter J. E. Tress W. A. Stickney

1974-01-01

110

Carbon emission limits required to satisfy future representative concentration pathways of greenhouse gases  

NASA Astrophysics Data System (ADS)

The response of the second-generation Canadian earth system model (CanESM2) to historical (1850-2005) and future (2006-2100) natural and anthropogenic forcing is assessed using the newly-developed representative concentration pathways (RCPs) of greenhouse gases (GHGs) and aerosols. Allowable emissions required to achieve the future atmospheric CO2 concentration pathways, are reported for the RCP 2.6, 4.5 and 8.5 scenarios. For the historical 1850-2005 period, cumulative land plus ocean carbon uptake and, consequently, cumulative diagnosed emissions compare well with observation-based estimates. The simulated historical carbon uptake is somewhat weaker for the ocean and stronger for the land relative to their observation-based estimates. The simulated historical warming of 0.9°C compares well with the observation-based estimate of 0.76 ± 0.19°C. The RCP 2.6, 4.5 and 8.5 scenarios respectively yield warmings of 1.4, 2.3, and 4.9°C and cumulative diagnosed fossil fuel emissions of 182, 643 and 1617 Pg C over the 2006-2100 period. The simulated warming of 2.3°C over the 1850-2100 period in the RCP 2.6 scenario, with the lowest concentration of GHGs, is slightly larger than the 2°C warming target set to avoid dangerous climate change by the 2009 UN Copenhagen Accord. The results of this study suggest that limiting warming to roughly 2°C by the end of this century is unlikely since it requires an immediate ramp down of emissions followed by ongoing carbon sequestration in the second half of this century.

Arora, V. K.; Scinocca, J. F.; Boer, G. J.; Christian, J. R.; Denman, K. L.; Flato, G. M.; Kharin, V. V.; Lee, W. G.; Merryfield, W. J.

2011-03-01

111

Enhanced adsorption of acidic gases (CO2, NO2 and SO2) on light metal decorated graphene oxide.  

PubMed

The adsorption of several acidic gases (CO2, NO2 and SO2) on light metal (Li, Al) decorated graphene oxide (GO) is theoretically studied, based on the first-principles calculations. Configuration relaxation, binding energy and charge transfer are carried out to discuss the acidic gas adsorption ability of light metal decorated GO. It is found out that Li, Al could be anchored stably by hydroxyl and epoxy groups on GO, and then a strong adsorption of CO2, NO2 and SO2 will occur above these light metals. In contrast to Ti, Li decorated GO exhibits a comparable adsorption ability of acidic gases, but a much smaller interaction with O2 about 2.85-3.98 eV lower in binding energy; and Al decorated GO displays much higher binding energy of all acidic gases with an enhancement of about 0.59-2.29 eV. The results of enhanced acidic gas adsorption ability and a reduced interference by O2 imply that Li, Al decorated GO may be useful and promising for collection and filtration of exhaust gases. PMID:24777197

Chen, Chi; Xu, Kui; Ji, Xiao; Miao, Ling; Jiang, Jianjun

2014-05-14

112

40 CFR 60.54a - Standard for municipal waste combustor acid gases.  

Code of Federal Regulations, 2010 CFR

...that affected facility any gases that contain sulfur dioxide...corrected to 7 percent oxygen (dry basis), whichever...that affected facility any gases that contain hydrogen...corrected to 7 percent oxygen (dry basis),...

2010-07-01

113

Equivalent Circuit Modeling for Carbon Nanotube Schottky Barrier Modulation in Polarized Gases  

NASA Technical Reports Server (NTRS)

We study the carbon nanotube Schottky barrier at the metallic electrode interface in polarized gases using an equivalent circuit model. The gas-nanotube interaction is often weak and very little charge transfer is expected [l]. This is the case with'oxygen, but the gas-electrode interaction is appreciable and makes the oxygen molecules negatively charged. In the closed circuit condition, screening positive charges appear in the nanotube as well as in the electrode, and the Schottky barrier is modulated due to the resultant electrostatic effects [2]. In the case of ammonia, both the gas-nanotube and gas-electrode interactions are weak, but the Schottky barrier can still be modulated since the molecules are polarized and align in the preferred orientation within the gap between the electrode and nanotube in the open circuit condition (dipole layer formation). In the closed circuit condition, an electric field appears in the gap and strengthens or weakens the preferred dipole alignment reflecting the nanotube Fermi level. The modulation is visible when the nanotube depletion mode is involved, and the required dipole density is as low as 2 x 10(exp 13) dipoles/sq cm, which is quite feasible experimentally,

Yamada, Toshishige

2005-01-01

114

The Role of Carbon Management Technologies in Addressing Atmospheric Stabilization of Greenhouse Gases  

SciTech Connect

Recent progress in decarbonization processes and engineered storage systems for CO2, together with preliminary cost estimates for these technologies, indicate that capture and storage of CO2 will have a major role to play in achieving deep reductions in emissions. These technologies hold the potential to reduce the cost of stabilizing the concentration of greenhouse gases, the ultimate objective of the UN Framework Convention on Climate Change (FCCC). Their value rises as the allowable level of cumulative carbon emissions declines. The value of these technologies is robust regardless of whether the world's economically recoverable oil and gas resources are eventually found to be large or small. This paper considers the economic implication of those advances in the context of long-term, global climate change mitigation strategies. This indicates the need for a broad, robust research and development strategy to reduce the cost of separating CO2 and to make accessible the widest range of storage reservoirs. It is also important to demonstrate excellent security of storage, in order to win public acceptance of the use of capture and storage techniques.

Edmonds, James A. (BATTELLE (PACIFIC NW LAB)); Freund, Paul F. (WASTE MANAGEMENT); Dooley, James J. (BATTELLE (PACIFIC NW LAB)); David Williams, Bob Durie, et. al.

2002-08-10

115

Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases Fiscal Year 2000 Annual Report  

SciTech Connect

The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has, since its inception in 1982, enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change, including concentrations of carbon dioxide (CO{sub 2}) and other radiatively active gases in the atmosphere; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; emissions of CO{sub 2} and other trace gases to the atmosphere; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea levels.

Cushman, R.M.

2001-11-15

116

Atmospheric Trace Gases, Carbon Isotopes, Radionuclides, and Aerosols: Atmospheric Carbon Dioxide Data from the Carbon Dioxide Information Analysis Center (CDIAC)  

DOE Data Explorer

CDIAC products include numeric data packages, publications, trend data, atlases, models, etc. and can be searched for by subject area, keywords, authors, product numbers, time periods, collection sites, spatial references, etc. Some of the collections may also be included in the CDIAC publication titled Trends Online: A Compendium of Global Change Data. Most datasets, many with numerous data files, are free to download from CDIAC's ftp area. Information related to atmospheric carbon dioxide data includes: Atmospheric Carbon Dioxide and Carbon Isotopes • Atmospheric carbon dioxide records from Mauna Loa, Hawaii • Monthly atmospheric CO2 mixing ratios and other data from the NOAA/CMDL continuous monitoring network • Data from the CSIRO GASLAB Flask Sampling Network • Atmospheric CO2 records from continuous measurements at Jubany Station, Antarctica and from 10 sites in the SIO air sampling network • Historical data from the extended Vostok ice core (2003) and the Siple Station ice core (1997) • Historical records from the Law Dome DE08, DE08-2, and DSS ice cores (1998) • AmeriFlux Carbon Dioxide, Water Vapor, and Energy Balance Measurements • Data from the Canadian Background Air Pollution Monitoring Network • Flask Samples from at U.S.S.R.-Operated Sites (1991) • The CISIRO (Australia) Monitoring Program from Aircraft for 1972-1981 • CO2 Concentrations in Surface Water and the Atmosphere during 1986-1989 NOAA/PMEL Cruises in the Pacific and Indian Oceans • Surface Water and Atmospheric CO2 and Nitrous Oxide Observations by Shipboard Automated Gas Chromatography: Results from Expeditions Between 1977 and 1990 (1992) • IPCC Working Group 1, 1994: Modeling Results Relating Future Atmospheric CO2 Concentrations to Industrial Emissions (1995). New datasets are added when available to the category of atmospheric carbon dioxide.

117

Mixed venous blood gases are superior to arterial blood gases in assessing acid-base status and oxygenation during acute cardiac tamponade in dogs.  

PubMed Central

Recent reports using anesthetized ventilator-dependent animal models, have suggested that in certain shock states, a disparity exists between arterial and mixed venous blood gases with regard to acid-base status and oxygenation. In a chronically instrumented unanesthetized canine model of acute cardiac tamponade breathing room air, we studied the effect of a graded decline in cardiac output on arterial and mixed venous pH, PCO2, and PO2. Cardiac tamponade resulted in a profound arterial respiratory alkalosis, whereas mixed venous pH, PCO2, and calculated serum bicarbonate levels remained relatively unchanged. As intrapericardial pressure increased and cardiac output declined, the difference between arterial and mixed venous PCO2 progressively increased. Further, whereas arterial oxygenation improved as cardiac output declined, mixed venous oxygenation steadily worsened. This disparity began early in cardiac tamponade (reductions in cardiac output of 20-40%) long before arterial blood pressure began to fall and progressively worsened as hemodynamic deterioration and lactic acidosis developed. Our findings are consistent with the hypothesis that a reduction in blood flow, resulting in decreased CO2 delivery to the lungs, is the primary mechanism responsible for the difference in pH and PCO2 observed between arterial and mixed venous blood. In this conscious, spontaneously breathing animal model, mixed venous blood gases thus are superior to arterial blood gases in assessing acid-base status and oxygenation, even early in acute cardiac tamponade when the decline in cardiac output is in the range of 20 to 40% and arterial blood pressure has not changed significantly.

Mathias, D W; Clifford, P S; Klopfenstein, H S

1988-01-01

118

Emissions of formaldehyde, acetic acid, methanol, and other trace gases from biomass fires in North Carolina measured by airborne Fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

Biomass burning is an important source of many trace gases in the global troposphere. We have constructed an airborne trace gas measurement system consisting of a Fourier transform infrared spectrometer (FTIR) coupled to a "flow-through" multipass cell (AFTIR) and installed it on a U.S. Department of Agriculture Forest Service King Air B-90. The first measurements with the new system were conducted in North Carolina during April 1997 on large, isolated biomass fire plumes. Simultaneous measurements included Global Positioning System (GPS); airborne sonde; particle light scattering, CO, and CO2; and integrated filter and canister samples. AFTIR spectra acquired within a few kilometers of the fires yielded excess mixing ratios for 10 of the most common trace gases in the smoke: water, carbon dioxide, carbon monoxide, methane, formaldehyde, acetic acid, formic acid, methanol, ethylene, and ammonia. Emission ratios to carbon monoxide for formaldehyde, acetic acid, and methanol were each 2.5±1%. This is in excellent agreement with (and confirms the relevance of) our results from laboratory fires. However, these ratios are significantly higher than the emission ratios reported for these compounds in some previous studies of "fresh" smoke. We present a simple photochemical model calculation that suggests that oxygenated organic compounds should be included in the assessment of ozone formation in smoke plumes. Our measured emission factors indicate that biomass fires could account for a significant portion of the oxygenated organic compounds and HOx present in the tropical troposphere during the dry season. Our fire measurements, along with recent measurements of oxygenated biogenic emissions and oxygenated organic compounds in the free troposphere, indicate that these rarely measured compounds play a major, but poorly understood, role in the HOx, NOx, and O3 chemistry of the troposphere.

Yokelson, R. J.; Goode, J. G.; Ward, D. E.; Susott, R. A.; Babbitt, R. E.; Wade, D. D.; Bertschi, I.; Griffith, D. W. T.; Hao, W. M.

1999-12-01

119

The air we breathe: three vital respiratory gases and the red blood cell: oxygen, nitric oxide, and carbon dioxide.  

PubMed

Three vital respiratory gases-oxygen (O(2)), nitric oxide (NO), and carbon dioxide (CO(2))-intersect at the level of the human red blood cell (RBC). In addition to hemoglobin (Hb)'s central role in O(2) transport, interaction of Hb with the Band 3 metabolon balances RBC energy flow. 2,3-Diphosphoglycerate enhances O(2) transport across the placenta and plays an important role in regulating RBC plasticity. NO is a key mediator of hypoxic vasodilation, but the precise role of RBC Hb remains controversial. In addition to established theories that depend on RBC uptake, delivery, and discharge of NO or its metabolites, an alternative hypothesis based on RBC permeability is suggested. NO depletion by free Hb may account for several clinical features seen during intravascular hemolysis or during deliberate infusion of Hb solutions used as RBC substitutes. CO(2) released by tissues triggers oxygen release through a series of well-coordinated reactions centered on the Band 3 metabolon. While RBC carbonic anhydrase and the Band 3 anion exchanger are central to this process, there is surprisingly little research on the kinetics of CO(2) clearance by transfusion. The three RBC gases are directly related to the three principal gases of Earth's atmosphere. Human fossil fuel consumption dumps 90 million metric tons of carbon into the atmosphere annually. Increasing CO(2) levels are linked to global warming, melting Arctic ice, rising sea levels, and climate instability. Just as individual cells depend on balance of the three vital gases, so too will their balance determine survival of life on Earth. PMID:21496039

Dzik, Walter H

2011-04-01

120

Sulfuric acid as an agent of carbonate weathering constrained by ?13C DIC: Examples from Southwest China  

NASA Astrophysics Data System (ADS)

Rock weathering by carbonic acid is thought to play an important role in the global carbon cycle because it can geologically sequestrate atmospheric CO 2. Current model of carbon cycle evolution usually assumes that carbonic acid is the major weathering agent and that other acids are not important. Here, we use carbon isotopic evidence and water chemistry of springs and rivers from the Beipanjiang River basin (Guizhou Province, Southwest China) to demonstrate that sulfuric acid is also an important agent of rock weathering. The ?13C of dissolved inorganic carbon (DIC) in the water samples ranges from - 13.1‰ to - 2.4‰, and correlates negatively to [HCO 3-]/([Ca 2+] + [Mg 2+]) ratios and positively to [SO 42-]/([Ca 2+] + [Mg 2+]) ratios. These relationships are interpreted as mixing diagrams between two reactions of carbonate weathering, using carbonic acid and sulfuric acid as a proton donor, respectively. Mixing proportions show that around 42% of the divalent cations in the spring water from Guizhou are originated from the interaction between carbonate minerals and sulfuric acid. It is shown that 40% of this sulfuric acid is derived from the atmosphere and has an anthropogenic origin. The remaining 60% are derived from the oxidative weathering of sulfide minerals in sedimentary rocks. Our results show the positive action of sulfuric acid on the chemical weathering of carbonate. Particularly, we show that sulfuric acid generated by coal combustion has increased by almost 20% the weathering rates of carbonate in Southwest China. This is a clear evidence that human activities are changing the weathering rates of rocks and demonstrates a negative feedback on the acidification of the ocean by greenhouse gases. Because of the involvement of sulfuric acid in weathering reactions, 63% of the alkalinity exported by rivers is derived from carbonate, instead of 50% when atmospheric CO 2 is the only acid involved in chemical weathering of carbonate. In the Guizhou Province, the weathering of carbonate is thus, at least transiently, a net source of CO 2 to the atmosphere. When extrapolated at global scale, sulfuric acid-induced carbonate weathering could counterbalance a significant part of the CO 2 consumed by silicate weathering. This paper highlights the competition between silicate weathering by carbonic acid and carbonate weathering by sulfuric acid for the regulation of the atmospheric CO 2 level.

Li, Si-Liang; Calmels, Damien; Han, Guilin; Gaillardet, Jérôme; Liu, Cong-Qiang

2008-06-01

121

Detection of a CO and NH3 gas mixture using carboxylic acid-functionalized single-walled carbon nanotubes.  

PubMed

Carbon nanotubes (CNT) are extremely sensitive to environmental gases. However, detection of mixture gas is still a challenge. Here, we report that 10 ppm of carbon monoxide (CO) and ammonia (NH3) can be electrically detected using a carboxylic acid-functionalized single-walled carbon nanotubes (C-SWCNT). CO and NH3 gases were mixed carefully with the same concentrations of 10 ppm. Our sensor showed faster response to the CO gas than the NH3 gas. The sensing properties and effect of carboxylic acid group were demonstrated, and C-SWCNT sensors with good repeatability and fast responses over a range of concentrations may be used as a simple and effective detection method of CO and NH3 mixture gas. PMID:23286690

Dong, Ki-Young; Choi, Jinnil; Lee, Yang Doo; Kang, Byung Hyun; Yu, Youn-Yeol; Choi, Hyang Hee; Ju, Byeong-Kwon

2013-01-01

122

Accounting for carbon cycle feedbacks in a comparison of the global warming effects of greenhouse gases  

Microsoft Academic Search

Greenhouse gases other than CO2 make a significant contribution to human-induced climate change, and multi-gas mitigation strategies are cheaper to implement than those which limit CO2 emissions alone. Most practical multi-gas mitigation strategies require metrics to relate the climate warming effects of CO2 and other greenhouse gases. Global warming potential (GWP), defined as the ratio of time-integrated radiative forcing of

Nathan P. Gillett; H. Damon Matthews

2010-01-01

123

Activated carbon catalytic ozonation of oxamic and oxalic acids  

Microsoft Academic Search

The oxidation of hazardous organic compounds leads to the formation of several by-products, being oxalic acid and oxamic acid final oxidation products refractory to ozonation. The present work aimed to study the ozonation of those carboxylic acids in the presence of activated carbon at different solution pH. For comparative purposes, experiments of adsorption on activated carbon, ozonation, and ozonation in

P. C. C. Faria; J. J. M. Órfão; M. F. R. Pereira

2008-01-01

124

A Widely Tunable Infrared Laser Spectrometer for Measurements of Isotopic Ratios of Carbon Cycle Gases  

SciTech Connect

The atmospheric abundances of carbon dioxide and methane have increased dramatically during the industrial era. Measurements of the isotopic composition of these gases can provide a powerful tool for quantifying their sources and sinks. This report describes the development of a portable instrument for isotopic analysis CO{sub 2} and CH{sub 4} using tunable infrared laser absorption spectroscopy. This instrument combines novel optical design and signal processing methods with a widely tunable mid-infrared laser source based on difference frequency generation (DFG) which will can access spectral regions for all the isotopes of CO{sub 2} and CH{sub 4} with a single instrument. The instrument design compensates for the large difference in concentration between major and minor isotopes by measuring them with path lengths which differ by a factor of 100 within the same multipass cell. During Phase I we demonstrated the basic optical design and signal processing by determining {sup 13}CO{sub 2} isotopic ratios with precisions as small as 0.2{per_thousand} using a conventional lead salt diode laser. During Phase II, the DFG laser source was coupled with the optical instrument and was demonstrated to detect {sup 13}CH{sub 4}/{sup 12}CH{sub 4} ratios with a precision of 0.5{per_thousand} and an averaging time of 20 s using concentrated methane in air with a mixing ratio of 2700 ppm. Methods for concentrating ambient air for isotopic analysis using this technique have been evaluated. Extensions of this instrument to other species such as {sup 13}CO{sub 2}, C{sup 18}OO, and CH{sub 3}D are possible by substituting lasers at other wavelengths in the DFG source module. The immediate commercial application of this instrument will be to compete with existing mass spectrometric isotope instruments which are expensive, large and relatively slow. The novel infrared source developed in this project can be applied to the measurement of many other gas species and will have wide application in atmospheric monitoring, industrial process control, and medical research and diagnostic development.

Joanne H. Shorter; J. Barry McManus; David D. Nelson; Charles E. Kolb; Mark S. Zahniser; Ray Bambha; Uwe Lehmann; Tomas Kulp; Stanley C. Tyler

2005-01-31

125

Low to middle tropospheric profiles and biosphere/troposphere fluxes of acidic gases in the summertime Canadian taiga  

NASA Technical Reports Server (NTRS)

We report features of acidic gases in the troposphere from 9 to 5000 m altitude above ground over the Canadian taiga in the summer of 1990. The measurements were conducted at a 30-m meteorological tower and from the NASA Wallops Electra aircraft as part of the joint U.S.-Canadian Arctic Boundary Layer Expedition (ABLE) 3B Northern Wetland Studies (NOWES). We sampled air for acidic gases using the mist chamber collector coupled with subsequent analysis using ion chromatography. At the tower we collected samples at two heights during a 13-day period, including diurnal studies. Using eddy flux and profile data, we estimated the biosphere/troposphere fluxes of nitric, formic, and acetic acids and sulfur dioxide. For the organic acids, emissions from the taiga in the afternoon hours and deposition during the predawn morning hours were observed. The flux intensities alone were however not high enough to explain the observed changes in mixing ratios. The measured deposition fluxes of nitric acid were high enough to have a significant influence on its mixing ratio in the boundary layer. On three days we measured vertical profiles of nitric, formic, and acetic acids through the lower to midtroposphere. We found that the chemical composition of the troposphere was extremely heterogenous. Pronounced layers of polluted air were readily apparent from our measurements. Local photochemical production and episodic long-range transport of trace components, originating from biomass burning and possibly industrial emissions, appear to have a strong influence on the composition of the troposphere and biosphere/troposphere fluxes of acidic gases at this site.

Klemm, O.; Talbot, R. W.; Fitzgerald, D. R.; Klemm, K. I.; Lefer, B. L.

1994-01-01

126

Comparative Climate Responses of Anthropogenic Greenhouse Gases, All Major Aerosol Components, Black Carbon, and Methane, Accounting for the Evolution of the Aerosol Mixing State and of Clouds/Precipitation from Multiple Aerosol Size Distributions  

NASA Astrophysics Data System (ADS)

Several modeling studies to date have simulated the global climate response of anthropogenic greenhouse gases and bulk (non-size-resolved) sulfate or generic aerosol particles together, but no study has examined the climate response of greenhouse gases simultaneously with all major size- and composition resolved aerosol particle components. Such a study is important for improving our understanding of the effects of anthropogenic pollutants on climate. Here, the GATOR-GCMOM model is used to study the global climate response of (a) all major greenhouse gases and size-resolved aerosol components, (b) all major greenhouse gases alone, (c) fossil-fuel soot (black carbon, primary organic matter, sulfuric acid, bisulfate, sulfate), and (d) methane. Aerosol components treated in all simulations included water, black carbon, primary organic carbon, secondary organic carbon, sulfuric acid, bisulfate, sulfate, nitrate, chloride, ammonium, sodium, hydrogen ion, soil dust, and pollen/spores. Fossil-fuel soot (FFS) was emitted into its own size distribution. All other components, including biofuel and biomass soot, sea-spray, soil dust, etc., were emitted into a second distribution (MIX). The FFS distribution grew by condensation of secondary organic matter and sulfuric acid, hydration of water, and dissolution of nitric acid, ammonia, and hydrochloric acid. It self-coagulated and heterocoagulated with the MIX distribution, which also grew by condensation, hydration, and dissolution. Treatment of separate distributions for FFS allowed FFS to evolve from an external mixture to an internal mixture. In both distributions, black carbon was treated as a core component for optical calculations. Both aerosol distributions served as CCN during explicit size-resolved cloud formation. The resulting clouds grew by coagulation and condensation, coagulated with interstitial aerosol particles, and fell to the surface as rain and snow, carrying aerosol constituents with them. Thus, cloud evolution accounted for the first and second indirect effects and the mixing state of aerosol particles. The optical properties of clouds were found by treating black carbon inclusions surrounded by a shell of water. The albedos of snow, sea ice, and water were calculated with radiative transfer solutions, assuming black carbon inclusions in the case of snow and sea ice. The simulations accounted for 3-D energy diffusion to the deep ocean and 2-D ocean circulation. Major conclusions are (a) the most important constituents of global warming, in terms of climate response, appear to be, in order, carbon dioxide, black carbon, and methane, (b) aerosol particles (all together) appear to act on top of greenhouse gases to enhance extremes in both regional cooling and regional warming, (b) the combination of important greenhouse gases and aerosol particles can explain observed major regions of historic warming and cooling, and (d) eliminating all anthropogenic aerosol emission could more than double current global warming but would have less of an effect than independently doubling carbon dioxide.

Jacobson, M. Z.

2005-12-01

127

The Perils of Carbonic Acid and Equilibrium Constants.  

ERIC Educational Resources Information Center

Discusses the effects caused by small amounts of carbon dioxide usually present in water and acid-base equilibria of dilute solutions. Notes that dilute solutions of most weak acids and bases undergo significant dissociation or protonation. (MVL)

Jencks, William P.; Altura, Rachel A.

1988-01-01

128

Removal potential of toxic 2378-substituted PCDD/F from incinerator flue gases by waste-derived activated carbons.  

PubMed

The application of activated carbons has become a commonly used emission control protocol for the removal or adsorption of persistent organic pollutants from the flue gas streams of waste incinerators. In this study, the 2378-substituted PCDD/F removal efficiency of three types of activated carbons derived from the pyrolysis of refuse derived fuel, textile waste and scrap tyre was investigated and compared with that of a commercial carbon. Experiments were carried out in a laboratory scale fixed-bed reactor under a simulated flue gas at 275°C with a reaction period of four days. The PCDD/F in the solid matrices and exhaust gas, were analyzed using gas chromatography coupled with a triple quadrupole mass spectrometer. In the absence of activated carbon adsorbent, there was a significant increase in the concentration of toxic PCDD/F produced in the reacted flyash, reaching up to 6.6 times higher than in the raw flyash. In addition, there was a substantial release of PCDD/F into the gas phase, which was found in the flue gas trapping system. By application of the different commercial, refuse derived fuel, textile and tyre activated carbons the total PCDD/F toxic equivalent removal efficiencies in the exhaust gas stream were 58%, 57%, 64% and 52%, respectively. In general, the removal of the PCDDs was much higher with an average of 85% compared to PCDFs at 41%. Analysis of the reacted activated carbons showed that there was some formation of PCDD/F, for instance, a total of 60.6 ?g I-TEQ kg(-1) toxic PCDD/F was formed in the refuse derived fuel activated carbon compared to 34 ?g I-TEQ kg(-1) in the commercial activated carbon. The activated carbons derived from the pyrolysis of waste, therefore, showed good potential as a control material for PCDD/F emissions in waste incinerator flue gases. PMID:21334872

Hajizadeh, Yaghoub; Onwudili, Jude A; Williams, Paul T

2011-06-01

129

Functionalized carbon nanofibers as solid-acid catalysts for transesterification.  

PubMed

Carbon nanofibers (CNFs) were functionalized with aryl sulfonic acid groups using in situ diazonium coupling. The use of diazonium coupling yielded an acidic carbon material, in which the introduced acidic groups are readily accessible to the triglyceride substrate. The material is an efficient catalyst for the transesterification of triolein and methanol, outperforming conventional sulfonated carbons in both stability and activity per acid site. Upon comparing CNFs with varying degrees of functionalization, a linear correlation between sulfonic acid sites and catalytic performance was found. PMID:23908100

Stellwagen, Daniel R; van der Klis, Frits; van Es, Daan S; de Jong, Krijn P; Bitter, Johannes H

2013-09-01

130

Helium and carbon isotopic compositions of hot spring gases in the Tibetan Plateau  

Microsoft Academic Search

The Tibetan Plateau is one of the most active geothermal areas in the Himalayan Geothermal Belt. However, the heat source of the geothermal manifestation is unknown because of a lack of Quaternary volcanoes in this area, except in western Yunnan and northern Tibet. In order to unravel the heat source and the origin of volatile components in hot spring gases

Tetsuya Yokoyama; Shun'ichi Nakai; Hiroshi Wakita

1999-01-01

131

The hyporheic zone as a source of dissolved organic carbon and carbon gases to a temperate forested stream  

USGS Publications Warehouse

The objective of this study was to examine chemical changes in porewaters that occur over small scales (cm) as groundwater flows through the hyporheic zone and discharges to a stream in a temperate forest of northern Wisconsin. Hyporheic-zone porewaters were sampled at discrete depths of 2, 10, 15, 61, and 183 cm at three study sites in the study basin. Chemical profiles of dissolved organic carbon (DOC), CO2, CH4, and pH show dramatic changes between 61 cm sediment depth and the water-sediment interface. Unless discrete samples at small depth intervals are taken, these chemical profiles are not accounted for. Similar trends were observed at the three study locations, despite each site having very different hydraulic-flow regimes. Increases in DOC concentration by an order of magnitude from 61 to 15 cm depth with a corresponding decrease in pH and rapid decreases in the molecular weight of the DOC suggest that aliphatic compounds (likely organic acids) are being generated in the hyporheic zone. Estimated efflux rates of DOC, CO2, and CH4 to the stream are 6.2, 0.79, 0.13 moles m2 d-1, respectively, with the vast majority of these materials produced in the hyporheic zone. Very little of these materials are accounted for by sampling stream water, suggesting rapid uptake and/or volatilization.

Schindler, J. E.; Krabbenhoft, D. P.

1998-01-01

132

Research and Development on Membrane Processes for Removal of Acid Gases During Coal Gasification. Final Report, 20 June 1975-19 October 1976.  

National Technical Information Service (NTIS)

The object of this program was to develop novel and unique membranes for separating acid gases from coal gasification streams. Many candidate membranes, including cationic, hydrophilic, and silicone, were tested. Optimum separation properties were possess...

R. J. Petersen J. E. Cadotte E. J. Conway R. H. Forester M. J. Steuck

1976-01-01

133

Carbon Dioxide Information Analysis Center and World Data Center-A for atmospheric trace gases: FY 1993 activities  

SciTech Connect

During the course of a fiscal year, Oak Ridge National Laboratory`s Carbon Dioxide Information Analysis Center (CDIAC) distributes thousands of specialty publications-numeric data packages (NDPs), computer model packages (CMPs), technical reports, public communication publications, newsletters, article reprints, and reference books-in response to requests for information related to global environmental issues, primarily those pertaining to climate change. CDIAC`s staff also provide technical responses to specific inquiries related to carbon dioxide (CO{sub 2}), other trace gases, and climate. Hundreds of referrals to other researchers, policy analysts, information specialists, or organizations are also facilitated by CDIAC`s staff. This report provides an account of the activities accomplished by CDIAC (including World Data Center-A for Atmospheric Trace Gases) during the period October 1, 1992, to September 30, 1993. An organizational overview of CDIAC and its staff is supplemented by a detailed description of inquiries received and CDIAC`s response to those inquiries. An analysis and description of the preparation and distribution of NDPS, CMPS, technical reports, newsletters, fact sheets, specialty publications, and reprints are provided. Comments and descriptions of CDIAC`s information management systems, professional networking, and special bilateral agreements are also presented.

Cushman, R.M. [Oak Ridge National Lab., TN (United States). Carbon Dioxide Information Analysis Center; Stoss, F.W. [Oak Ridge National Lab., TN (United States). Carbon Dioxide Information Analysis Center]|[Univ. of Tennessee, Knoxville, TN (United States). Energy, Environment, and Resources Center

1994-01-01

134

USE OF FATTY ACID STABLE CARBON ISOTOPE RATIO TO INDICATE MICROBIAL CARBON SOURCE IN TROPICAL SOILS  

EPA Science Inventory

We use measurements of the concentration and stable carbon isotope ratio of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels, broad microbial community structure, and microbial carbon source. For studies of soil o...

135

The acid rain\\/carbon dioxide threat — Control strategies  

Microsoft Academic Search

Many of the world's most troublesome problems are closely interrelated. A case in point is the acid rain\\/carbon dioxide threat. Acid rain is the commonly used synonym for the major ingredients in the ongoing regional forest dieback, and carbon dioxide is a major influencing factor in the man-induced global geophysical experiment which is feared to lead to unacceptable climatic changes.

Wilfrid Bach

1985-01-01

136

sp³ -linked amorphous carbon with sulfonic acid groups as a heterogeneous acid catalyst.  

PubMed

SO?H-bearing amorphous carbon prepared from polyvinyl chloride (PVC) is studied as a heterogeneous Brønsted acid catalyst. Sulfonation of partially carbonized PVC produces amorphous carbon consisting of small SO?H-bearing carbon sheets linked by sp³ -based aliphatic hydrocarbons. This carbon material exhibits much higher catalytic performance in the hydrolysis of cellobiose than conventional heterogeneous Brønsted acid catalysts with SO?H groups, including SO?H-bearing amorphous carbon derived from cellulose. This can be attributed to a high density of SO?H groups and the fast diffusion of reactants and products enabled by a flexible carbon network. PMID:22740285

Suganuma, Satoshi; Nakajima, Kiyotaka; Kitano, Masaaki; Hayashi, Shigenobu; Hara, Michikazu

2012-09-01

137

Numerical and experimental investigation of acid wormholing during acidization of vuggy carbonate rocks  

Microsoft Academic Search

Both small- (micron) to large- (centimeter) scale heterogeneities in carbonates cause the injected acids to propagate very differently than that predicted by a homogeneous model. Very few studies, either theoretical or experimental, address the effect of large scale heterogeneities (vugs) on matrix acidizing.This study explores the effects of heterogeneity on vuggy carbonate acidizing with high resolution computerized tomography imaging, image

Omer Izgec; Ding Zhu; Alfred D. Hill

2010-01-01

138

Activated carbons prepared from phosphoric acid activation of grain sorghum  

Microsoft Academic Search

The production of activated carbons from grain sorghum with phosphoric acid activation has been studied by means of two processes, i.e., one-stage and two-stage. The former comprises simultaneous carbonization and activation after impregnation; the latter, the carbonization of the precursor at 300 °C for 15 min, followed by the activation of the resultant char after impregnation with phosphoric acid. The

Yulu Diao; W. P Walawender; L. T Fan

2002-01-01

139

High rate chemical vapor deposition of carbon films using fluorinated gases  

DOEpatents

A high rate, low-temperature deposition of amorphous carbon films is produced by PE-CVD in the presence of a fluorinated or other halide gas. The deposition can be performed at less than 100.degree. C., including ambient room temperature, with a radio frequency plasma assisted chemical vapor deposition process. With less than 6.5 atomic percent fluorine incorporated into the amorphous carbon film, the characteristics of the carbon film, including index of refraction, mass density, optical clarity, and chemical resistance are within fifteen percent (15%) of those characteristics for pure amorphous carbon films, but the deposition rates are high.

Stafford, Byron L. (Arvada, CO); Tracy, C. Edwin (Golden, CO); Benson, David K. (Golden, CO); Nelson, Arthur J. (Longmont, CO)

1993-01-01

140

Choices in calculating life cycle emissions of carbon containing gases associated with forest derived biofuels  

Microsoft Academic Search

Life cycle studies concerning carbon dioxide emissions associated with biofuels from forests may consider emissions originating in the use of fossil fuels and biogenic emissions. When both types of emissions are considered, emission factors are dependent on choices as to time-frame, land-use scenario, allocation of sequestration and fate of sequestered carbon after fuel wood harvesting. Dependent on such choices life

L. Reijnders; M. A. J Huijbregts

2003-01-01

141

Trends in source gases  

NASA Technical Reports Server (NTRS)

Source gases are defined as those gases that, by their breakdown, introduce into the stratosphere halogen, hydrogen, and nitrogen compounds that are important in stratospheric ozone destruction. Given here is an update of the existing concentration time series for chlorocarbons, nitrous oxide, and methane. Also reviewed is information on halogen containing species and the use of these data for establishing trends. Also reviewed is evidence on trends in trace gases that influence tropospheric chemistry and thus the tropospheric lifetimes of source gases, such as carbon dioxide, carbon monoxide, or nitrogen oxides. Much of the information is given in tabular form.

Ehhalt, D. H.; Fraser, P. J.; Albritton, D.; Cicerone, R. J.; Khalil, M. A. K.; Legrand, M.; Makide, Y.; Rowland, F. S.; Steele, L. P.; Zander, R.

1989-01-01

142

Nature of the carbon and sulfur phases and inorganic gases in the Kenna ureilite  

NASA Technical Reports Server (NTRS)

Abundances of carbon and sulfur in the Kenna ureilite are 2.219 plus or minus 0.060 wt. % C and 0.179 plus or minus 0.008 wt. % S. Secondary carbonates resulting from terrestrial weathering account for 0.25 plus or minus 0.02 wt. % C. No hydrocarbons were detected during gas release measurements. Most of the carbon is in graphite, diamond, or lonsdaleite. The sample of Kenna contained 0.95 plus or minus 0.05 wt.% H2O. Total carbon and sulfur measurements were made on three additional ureilites: Havero, Dingo Pup Donga, and North Haig. Ureilite carbon abundances are similar to those of C-2 chondrites, whereas sulfur abundances are a factor of 10 less than C-2 chondrites and ordinary chondrites. The elemental abundances, ratios, and phases present in the ureilites rule out a direct genetic relationship between the ureilites and the carbonaceous chondrites.

Gibson, E. K., Jr.

1976-01-01

143

Acid Rain  

NSDL National Science Digital Library

Due to the presence of dissolved gases such as carbon dioxide, rainfall is naturally acidic. The release of other gases and chemicals such as sulfur dioxide during the combustion of coal and oil can cause rainfall to become even more acidic, sometimes to the point of toxicity. In this activity, students will measure the pH of local rainfall to see what effect these gases have in their region. They will also check an online resource to see how the releases of acid rain-causing chemicals have varied over the past 20 years, and answer questions about the information they uncover.

Fox, Chris

144

Apparatus for purifying arsine, phosphine, ammonia, and inert gases to remove Lewis acid and oxidant impurities therefrom  

DOEpatents

An apparatus for purifying a gaseous mixture comprising arsine, phosphine, ammonia, and/or inert gases, to remove Lewis acid and/or oxidant impurities therefrom, comprising a vessel containing a bed of a scavenger, the scavenger including a support having associated therewith an anion which is effective to remove such impurities, such anion being selected from one or more members of the group consisting of: (i) carbanions whose corresponding protonated compounds have a pK.sub.a value of from about 22 to about 36; and (ii) anions formed by reaction of such carbanions with the primary component of the mixture.

Tom, Glenn M. (New Milford, CT); Brown, Duncan W. (Wilton, CT)

1991-01-08

145

Sorption of noble gases by solids, with reference to meteorites. I - Magnetite and carbon  

NASA Astrophysics Data System (ADS)

The trapping of meteoritic noble gases by solids is simulated through the synthesis of 18 Fe3O4 samples at 350-720 K in a noble gas atmosphere, by means of the reactions: (1) 3Fe + 4H2O yields Fe3O4 + 4H2, using Ne, Ar, Kr and Xe; and (2) 3Fe + 4CO yields Fe3O4 + 4C + carbides, using Xe. Etching experiments suggest an analogy with 'Phase Q' in meteorites. Adsorbed atmospheric gases are present in all samples, and dominate whenever the noble gas partial pressure in the atmosphere is greater than that in the synthesis. While many of the results of Lancet and Anders (1973) appear to have been dominated by such an atmospheric component, others are suspect. When the doubtful samples of Lancet and Anders are corrected or eliminated, the fractionation pattern no longer peaks at Ar, but rather, as in the present sample, rises monotonically from Ne to Xe. No evidence is found for the earlier study's claim of a strong temperature dependence.

Yang, J.; Lewis, R. S.; Anders, E.

1982-06-01

146

Coal fly ash based carbons for SO 2 removal from flue gases  

Microsoft Academic Search

Two different coal fly ashes coming from the burning of two coals of different rank have been used as a precursor for the preparation of steam activated carbons. The performance of these activated carbons in the SO2 removal was evaluated at flue gas conditions (100°C, 1000ppmv SO2, 5% O2, 6% H2O). Different techniques were used to determine the physical and

B. Rubio; M. T. Izquierdo

2010-01-01

147

Carbon Dioxide Information Analysis Center and World Data Center for Atmospheric Trace Gases Fiscal Year 2001 Annual Report  

SciTech Connect

The Carbon Dioxide Information Analysis Center (CDIAC), which includes the World Data Center (WDC) for Atmospheric Trace Gases, is the primary global change data and information analysis center of the U.S. Department of Energy (DOE). More than just an archive of data sets and publications, CDIAC has, since its inception in 1982, enhanced the value of its holdings through intensive quality assurance, documentation, and integration. Whereas many traditional data centers are discipline-based (for example, meteorology or oceanography), CDIAC's scope includes potentially anything and everything that would be of value to users concerned with the greenhouse effect and global climate change, including concentrations of carbon dioxide (CO{sub 2}) and other radiatively active gases in the atmosphere; the role of the terrestrial biosphere and the oceans in the biogeochemical cycles of greenhouse gases; emissions of CO{sub 2} and other trace gases to the atmosphere; long-term climate trends; the effects of elevated CO{sub 2} on vegetation; and the vulnerability of coastal areas to rising sea levels. CDIAC is located within the Environmental Sciences Division (ESD) at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. CDIAC is co-located with ESD researchers investigating global-change topics, such as the global carbon cycle and the effects of carbon dioxide on climate and vegetation. CDIAC staff are also connected with current ORNL research on related topics, such as renewable energy and supercomputing technologies. CDIAC is supported by the Environmental Sciences Division (Jerry Elwood, Director) of DOE's Office of Biological and Environmental Research. CDIAC represents DOE in the multi-agency Global Change Data and Information System (GCDIS). Wanda Ferrell is DOE's Program Manager with overall responsibility for CDIAC. Roger Dahlman is responsible for CDIAC's AmeriFlux tasks, and Anna Palmisano for CDIAC's Ocean Data tasks. CDIAC is made up of three groups: Data Systems, Information Services, and Computer Systems, with nineteen full-time or part-time staff. The following section provides details on CDIAC's staff and organization. The Data Systems Group identifies and obtains databases important to global-change research; analyzes data; compiles needed databases; provides data management and support to specific programs [e.g., NARSTO, Free-Air CO{sub 2} Enrichment (FACE), AmeriFlux, Oceans]; and prepares documentation to ensure the long-term utility of CDIAC's data holdings. The Information Services Group responds to data and information requests; maintains records of all request activities; analyzes user statistics; assists in Web development and maintenance; and produces CDIAC's newsletter (CDIAC Communications), the fiscal year annual reports, and various information materials. The Computer Systems Group provides computer system support for all CDIAC and WDC activities; designs and maintains CDIAC's computing system network; ensures compliance with ORNL/DOE computing security regulations; ensures long-term preservation of CDIAC data holdings through systematic backups; evaluates, develops, and implements software; ensures standards compliance; generates user statistics; provides Web design, development, and oversight; and provides systems analysis and programming assistance for scientific data projects.

Cushman, R.M.

2002-10-15

148

Potential effects of clean coal technologies on acid precipitation, greenhouse gases, and solid waste disposal  

SciTech Connect

The US Department of Energy`s (DOE`s) Clean Coal Technology Demonstration Program (CCTDP) was initially funded by Congress to demonstrate more efficient, economically feasible, and environmentally acceptable coal technologies. Although the environmental focus at first was on sulfur dioxide (SO{sub 2}) and nitrogen oxides (NO{sub x}) because their relationship to acid precipitation, the CCTDP may also lead to reductions in carbon dioxide (CO{sub 2}) emissions and in the volume of solid waste produced, compared with conventional technologies. The environmental effects of clean coal technologies (CCTs) depend upon which (if any) specific technologies eventually achieve high acceptance in the marketplace. In general, the repowering technologies and a small group of retrofit technologies show the most promise for reducing C0{sub 2} emissions and solid waste. These technologies also compare favorably with other CCTs in terms of SO{sub 2} and NO{sub x} reductions. The upper bound for CO{sup 2} reductions in the year 2010 is only enough to reduce global ``greenhouse`` warming potential by about 1%. However, CO{sub 2} emissions come from such variety of sources around the globe that no single technological innovation or national policy change could realistically be expected to reduce these emissions by more than a few percent. Particular CCTs can lead to either increases or decreases in the amount of solid waste produced. However, even if decreases are not achieved, much of the solid waste from clean coal technologies would be dry and therefore easier to dispose of than scrubber sludge.

Blasing, T.J.; Miller, R.L.; McCold, L.N.

1993-11-01

149

Do Agricultural Soils of California have the Potential to Sequester Carbon and Mitigate Greenhouse Gases?  

NASA Astrophysics Data System (ADS)

Agricultural ecosystems play a major role in the global carbon cycle and can be both sources of carbon emissions to the atmosphere and also carbon sinks which may be used to offset any future greenhouse gas (GHG) emissions. In California, climate change predictions indicate major impacts and substantial alterations of agricultural systems over the next decades. In 2006, California passed the California Global Warming Solutions Act of 2006 (AB 32) that requires reduction of the three major GHG's (CO2, N2O and CH4) to 1990 levels by 2020. We surveyed and synthesized available data from recent studies describing the potential to sequester carbon and reduce other GHG emissions in California agricultural soils. The studies evaluated various management practices in both annual row and perennial cropping systems, with other studies focusing upon biogeochemical model predictions for carbon sequestration and GHG mitigation calibrated towards California agriculture. Management practices considered included minimum or no tillage, cover cropping, organic residue (low and high inputs) and nitrogen fertilizer management. Though practices involving inputs of carbon, such as cover cropping and organic amendments, were often associated with increases in soil organic carbon (SOC) in the top soil layer (0-20 cm), results were not consistent across farming systems. Several studies indicated that conservation tillage, alone, increased above-ground biomass, especially when used with a cover crop. However, the reduced soil disturbance from conservation tillage merely resulted in a redistribution of the soil carbon rather than an overall accumulation, when compared with standard tillage and cover cropping practices together. Predictions from biogeochemical models indicated that increased inputs of manure and increased organic residues led to substantial carbon sequestration but did not consistently reduce non-CO2 related GHG emissions. The most effective way to reduce non-CO2 GHG emissions, and simultaneously add organic matter to soil, was to employ reduced tillage techniques and low input farming which is based upon the reduction of chemical fertilizers, pesticides and herbicides without their complete elimination and to also add carbon to the soils through the addition and incorporation of organic amendments and cover crops.

Suddick, E. C.; Scow, K. M.; Six, J. W.

2008-12-01

150

Solid Sulfonic Acid Catalysts Based on Porous Carbons and Carbon-Silica Composites  

NASA Astrophysics Data System (ADS)

Mesoporous carbons prepared using a templating method under different carbonization temperatures are sulfonated with concentrated H2SO4. Without the moving of silica template carbon-silica composites were prepared, which can maintain the pore structure well during sulfonation reaction process. The resultant samples are characterized using nitrogen adsorption, transmission electron microscope, field-emission scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, and elemental analysis techniques. The catalytic performances of the sulfonated carbons and composites are evaluated by esterification reaction of methanol with acetic acid. The results show that a low-temperature carbonization process is favorable for improving the reaction conversion of acetic acid. In addition, the sulfonated carbon-silica composites show a higher acetic acid conversion than the sulfonated mesoporous carbons.

Tian, Xiao Ning; Luo, Lijuan; Jiang, Zhongqing; Zhao, X. S.

151

Control of mercury emissions in flue gases by activated carbon adsorption  

SciTech Connect

The adsorptive capacities of virgin and sulfur impregnated activated carbons (GAC) for gas-phase mercury were evaluated as a function of temperature and influent mercury concentration. The virgin activated carbon showed little adsorptive capacity, especially at temperatures above 90 {degrees}C. The pronounced effect of temperature on the adsorptive capacity evidences a physical adsorption mechanism between the mercury and virgin GAC. Sulfur impregnated activated carbons exhibited enhanced mercury removal efficiency over the non-impregnated varieties due to formation of mercuric sulfide on the carbon surface. This chemisorption process is enhanced with increased temperature between 25 and 90 {degrees}C. However, at 140 {degrees}C a decrease in adsorptive capacity occurs, indicating reduced formation of mercuric sulfide. The method used for impregnating GAC with sulfur had a pronounced effect on mercury removal capacity. The chemical bonding of sulfur and carbon surface at 600 {degrees}C provides a more uniform distribution of sulfur throughout the GAC pore structure than achieved by conventional condensation techniques, yielding improved performance.

Vidic, R.D. [Univ. of Pittsburgh, PA (United States)

1996-12-31

152

Evaluation of carbon dioxide mass transfer in raceway reactors for microalgae culture using flue gases.  

PubMed

Mass transfer of CO2 from flue gas was quantified in a 100m(2) raceway. The carbonation sump was operated with and without a baffle at different liquid/gas ratios, with the latter having the greatest influence on CO2 recovery from the flue gas. A rate of mass transfer sufficient to meet the demands of an actively growing algal culture was best achieved by maintaining pH at ?8. Full optimisation of the process required both pH control and selection of the best liquid/gas flow ratio. A carbon transfer rate of 10gCmin(-1) supporting an algal productivity of 17gm(-2)day(-1) was achieved with only 4% direct loss of CO2 in the sump. 66% of the carbon was incorporated into biomass, while 6% was lost by outgassing and the remainder as dissolved carbon in the liquid phase. Use of a sump baffle required additional power without significantly improving carbon mass transfer. PMID:24374031

de Godos, I; Mendoza, J L; Acién, F G; Molina, E; Banks, C J; Heaven, S; Rogalla, F

2014-02-01

153

Procedures for safe handling of off-gases from electric vehicle lead-acid batteries during overcharge  

NASA Astrophysics Data System (ADS)

The potential for generation of toxic gases from lead-acid batteries has long been recognized. Prior to the current interest in electric vehicles, there were no studies specificaly oriented to toxic gas release from traction batteries, however. As the Department of Energy Demonstration Project (in the Electric and Hybrid Vehicle Program) progresses, available data from past studies and parallel health effects programs must be digested into guidance to the drivers and maintenance personnel, tailored to their contact with electric vehicles. The basic aspects of lead-acid battery operation, vehicle use, and health effects of stibine and arsine to provide electric vehicle users with the information behind the judgment that vehicle operation and testing may proceed are presented. Specifically, it is concluded that stibine generation or arsine generation at rapid enough rates to induce acute toxic response is not at all likely. Procedures to guard against low-level exposure until more definitive data on ambient concentrations of the gases are collected are presented for both charging the batteries and driving the vehicles. A research plan to collect additional quantitative data from electric traction batteries is presented.

Labelle, S. J.; Bhattacharyya, M. H.; Loutfy, R. O.; Varma, R.

1980-01-01

154

Procedures for safe handling of off-gases from electric vehicle lead-acid batteries during overcharge  

SciTech Connect

The potential for generation of toxic gases from lead-acid batteries has long been recognized. Prior to the current interest in electric vehicles, there were no studies specificaly oriented to toxic gas release from traction batteries, however. As the Department of Energy Demonstration Project (in the Electric and Hybrid Vehicle Program) progresses, available data from past studies and parallel health effects programs must be digested into guidance to the drivers and maintenance personnel, tailored to their contact with electric vehicles. The basic aspects of lead-acid battery operation, vehicle use, and health effects of stibine and arsine to provide electric vehicle users with the information behind the judgment that vehicle operation and testing may proceed are presented. Specifically, it is concluded that stibine generation or arsine generation at rapid enough rates to induce acute toxic response is not at all likely. Procedures to guard against low-level exposure until more definitive data on ambient concentrations of the gases are collected are presented for both charging the batteries and driving the vehicles. A research plan to collect additional quantitative data from electric traction batteries is presented.

LaBelle, S.J.; Bhattacharyya, M.H.; Loutfy, R.O.; Varma, R.

1980-01-25

155

Atmospheric Trace Gases, Carbon Isotopes, Radionuclides, and Aerosols: Aerosols Data from the Carbon Dioxide Information Analysis Center (CDIAC)  

DOE Data Explorer

(Scroll down to find Aerosols, a subheading under the broader heading of Atmospheric Trace Gases, etc.) CDIAC products are indexed and searchable through a customized interface powered by ORNL's Mercury search engine. Products include numeric data packages, publications, trend data, atlases, models, etc. and can be searched for by subject area, keywords, authors, product numbers, time periods, collection sites, spatial references, etc. Some of the collections may also be included in the CDIAC publication Trends Online: A Compendium of Global Change Data. Most data sets, many with numerous data files, are free to download from CDIAC's ftp area. Information related to aerosols includes: • Rattlesnake Mountain Observatory (46.4 degrees N, 119.6 degrees W) Multispectral Optical Depth Measurements: 1979 - 1994 (1996) • Volcanic Loading: The Dust Veil Index (1985) (Specialized Interface)

156

Atmospheric Trace Gases, Carbon Isotopes, Radionuclides, and Aerosols: Radionuclides Data from the Carbon Dioxide Information Analysis Center (CDIAC)  

DOE Data Explorer

(Scroll down to Radionuclides, a subheading under the broader heading of Atmospheric Trace Gases, etc.) CDIAC products are indexed and searchable through a customized interface powered by ORNL's Mercury search engine. Products include numeric data packages, publications, trend data, atlases, and models and can be searched for by subject area, keywords, authors, product numbers, time periods, collection sites, spatial references, etc. Some of the collections may also be included in the CDIAC publication Trends Online: A Compendium of Global Change Data. Most data sets, many with numerous data files, are free to download from CDIAC's ftp area. Information related to radionuclides includes: • EML's Stratospheric Radionuclide (RANDAB) and Trace Gas (TRACDAB) Databases (1997) (Specialized Interface)

157

Atmospheric Trace Gases, Carbon Isotopes, Radionuclides, and Aerosols: Atmospheric Hydrogen Data from the Carbon Dioxide Information Analysis Center (CDIAC)  

DOE Data Explorer

(Scroll down to find Atmospheric Hydrogen, a subheading under the broader heading of Atmospheric Trace Gases, etc.) CDIAC products are indexed and searchable through a customized interface powered by ORNL's Mercury search engine. Products include numeric data packages, publications, trend data, atlases, and models and can be searched for by subject area, keywords, authors, product numbers, time periods, collection sites, spatial references, etc. Some of the collections may also be included in the CDIAC publication Trends Online: A Compendium of Global Change Data. Most data sets, many with numerous data files, are free to download from CDIAC's ftp area. Information related to atmospheric hydrogen includes: • Atmospheric H2 Concentrations from the CSIRO GASLAB Flask Sampling Network (Trends Online) (Specialized Interface)

158

Empirical carbon isotope\\/maturity relationships for gases from algal kerogens and terrigenous organic matter, based on dry, open-system pyrolysis  

Microsoft Academic Search

Pyrolyses experiments (dry, open-system) on algal kerogens and landplant material (Berner et al., 1995) have shown that carbon isotopic variations of methane, ethane and propane obtained from laboratory simulations mimic isotope variations of natural thermal gases. These isotope variations can be approximated through kinetic models (Berner et al., 1995). Also, maturity parameters like vitrinite reflectance and Rock-Eval Tmax are reliably

Ulrich Berner; Eckhard Faber

1996-01-01

159

Sorption of acid dyes from effluents using activated carbon  

Microsoft Academic Search

The sorption of three acid dyes, namely, Acid Red 114, Polar Yellow and Polar Blue RAWL, onto activated carbon, has been studied. Equilibrium isotherms have been measured for three single component systems (AB, AR, AY) and one binary component system (AB+AY). The isotherms were determined by shaking 0.05 g activated carbon, particle size range 500–710 ?m, with 0.05 dm3 dye

Keith K. H. Choy; Gordon McKay; John F. Porter

1999-01-01

160

Carbonic Anhydrase 5 Regulates AcidBase Homeostasis in Zebrafish  

Microsoft Academic Search

The regulation of the acid-base balance in cells is essential for proper cellular homeostasis. Disturbed acid-base balance directly affects cellular physiology, which often results in various pathological conditions. In every living organism, the protein family of carbonic anhydrases regulate a broad variety of homeostatic processes. Here we describe the identification, mapping and cloning of a zebrafish carbonic anhydrase 5 (ca5)

Ruben Postel; Arnoud Sonnenberg

2012-01-01

161

Porosity in granular carbons activated with phosphoric acid  

Microsoft Academic Search

Three series of activated carbon have been prepared by heat treatment of peach stones impregnated with solutions of phosphoric acid, in order to analyze the effect of phosphoric acid on the yield, bulk density and porosity of the resultant activated carbons. The analysis of the adsorption isotherms of N2 at 77 K. CO2 at 273 K and n-C4H10, at 273

M. Molina-Sabio; F. RodRíguez-Reinoso; F. Caturla; M. J. Sellés

1995-01-01

162

MATHEMATICAL AND EXPERIMENTAL INVESTIGATION ON NOX RECOVERY IN FLUIDIZED BED ADSORBERS FOR EXHAUST GASES OF NITRIC ACID PLANTS  

Microsoft Academic Search

A mathematical model for sorption of NOx from exhaust gas of nitric acid plants by activated carbon (AC) in a fluidized bed is proposed based on two-phase flow theory of fluidization. To solve the proposed model a computer program has been developed. The output of this program reveals the effects of various parameters such as temperature, inlet gas velocity, particle

D. MOWLA; S. RAZAVI

2004-01-01

163

40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2010 CFR

...gases, organics, and nitrogen oxides. 62.14103 Section 62...gases, organics, and nitrogen oxides. (a) The emission limits...facility any gases that contain: cadmium in excess of 0.040 milligrams...gases that contain nitrogen oxides in excess of the emission...

2010-07-01

164

40 CFR 62.14103 - Emission limits for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2010 CFR

...gases, organics, and nitrogen oxides. 62.14103 Section 62...gases, organics, and nitrogen oxides. (a) The emission limits...facility any gases that contain: cadmium in excess of 0.040 milligrams...gases that contain nitrogen oxides in excess of the emission...

2009-07-01

165

The role of precursor gases on the surface restructuring of catalyst films during carbon nanotube growth  

NASA Astrophysics Data System (ADS)

Catalyst films undergo considerable surface morphology restructuring prior to carbon nanotube nucleation, deeply influencing the nanostructures obtained. Here we study the influence of different gaseous atmospheres on the structure of thin Fe films. The morphology is influenced by process temperature and substrate interactions and varying the gas type and pressure can control the average catalyst island height.

Pisana, S.; Cantoro, M.; Parvez, A.; Hofmann, S.; Ferrari, A. C.; Robertson, J.

2007-03-01

166

Coal fly ash based carbons for SO2 removal from flue gases.  

PubMed

Two different coal fly ashes coming from the burning of two coals of different rank have been used as a precursor for the preparation of steam activated carbons. The performance of these activated carbons in the SO(2) removal was evaluated at flue gas conditions (100 degrees C, 1000 ppmv SO(2), 5% O(2), 6% H(2)O). Different techniques were used to determine the physical and chemical characteristics of the samples in order to explain the differences found in their behaviour. A superior SO(2) removal capacity was shown by the activated carbon obtained using the fly ash coming from a sub-bituminous-lignite blend. Experimental results indicated that the presence of higher amount of certain metallic oxides (Ca, Fe) in the carbon-rich fraction of this fly ash probably has promoted a deeper gasification in the activation with steam. A more suitable surface chemistry and textural properties have been obtained in this case which explains the higher efficiency shown by this sample in the SO(2) removal. PMID:20167465

Rubio, B; Izquierdo, M T

2010-07-01

167

Carbon dioxide production from combustion exhaust gases with nitrogen and argon by-product recovery  

Microsoft Academic Search

This patent describes a method for producing carbon dioxide and nitrogen from combustion exhaust gas containing less than about 10% oxygen by weight. It comprises treating the exhaust gas to remove particulate matter; compressing the exhaust gas to a pressure in the range from about 25 psia to about 200 psia; purifying the exhaust gas to remove trace contaminants; separating

R. Krishnamurthy; M. J. Andrecovich

1992-01-01

168

Swellable, water- and Acid-tolerant polymer sponges for chemoselective carbon dioxide capture.  

PubMed

To impact carbon emissions, new materials for carbon capture must be inexpensive, robust, and able to adsorb CO2 specifically from a mixture of other gases. In particular, materials must be tolerant to the water vapor and to the acidic impurities that are present in gas streams produced by using fossil fuels to generate electricity. We show that a porous organic polymer has excellent CO2 capacity and high CO2 selectivity under conditions relevant to precombustion CO2 capture. Unlike polar adsorbents, such as zeolite 13x and the metal-organic framework, HKUST-1, the CO2 adsorption capacity for the hydrophobic polymer is hardly affected by the adsorption of water vapor. The polymer is even stable to boiling in concentrated acid for extended periods, a property that is matched by few microporous adsorbents. The polymer adsorbs CO2 in a different way from rigid materials by physical swelling, much as a sponge adsorbs water. This gives rise to a higher CO2 capacities and much better CO2 selectivity than for other water-tolerant, nonswellable frameworks, such as activated carbon and ZIF-8. The polymer has superior function as a selective gas adsorbent, even though its constituent monomers are very simple organic feedstocks, as would be required for materials preparation on the large industrial scales required for carbon capture. PMID:24874971

Woodward, Robert T; Stevens, Lee A; Dawson, Robert; Vijayaraghavan, Meera; Hasell, Tom; Silverwood, Ian P; Ewing, Andrew V; Ratvijitvech, Thanchanok; Exley, Jason D; Chong, Samantha Y; Blanc, Frédéric; Adams, Dave J; Kazarian, Sergei G; Snape, Colin E; Drage, Trevor C; Cooper, Andrew I

2014-06-25

169

Phosphorylated Mesoporous Carbon as a Solid Acid Catalyst  

SciTech Connect

Mesoporous carbon catalyst supports are attractive due to their wide chemical stability while potentially increasing masstransport through and providing a path for larger molecules to access catalytic sites. Herein we report the synthesis of a 10 phosphorylated mesoporous carbon solid-acid catalyst characterized by NH3-TPD and isopropanol dehydration.

Dai, Sheng [ORNL; Mayes, Richard T [ORNL; Fulvio, Pasquale F [ORNL; Ma, Zhen [ORNL

2011-01-01

170

Removal of formaldehyde, methanol, dimethylether and carbon monoxide from waste gases of synthetic resin-producing industries.  

PubMed

The removal of mixtures of gas-phase pollutants released from formaldehyde- and formaldehyde resin-producing industries was studied in different bioreactor systems. The waste gases contained formaldehyde, methanol, dimethylether and carbon monoxide. The use of a hybrid two-stage bioreactor, composed of a biotrickling filter and a conventional biofilter connected in series, led to very high elimination capacities and removal efficiencies close to 100% for overall pollutant loads exceeding 600g m(-3)h(-1). The presence of low concentrations of dimethylether in the gaseous mixture did not have a significant effect on the removal of formaldehyde or methanol under our operating conditions, although moderate concentrations of these compounds did negatively affect the biodegradation of dimethylether. When a mixture of all four compounds, at concentrations around 100, 100, 50 and 50mg m(-3) for formaldehyde, methanol, carbon monoxide and dimethylether, respectively, was fed to a conventional biofilter, removal efficiencies higher than 80% were obtained for the first three pollutants at empty bed retention time values above 30s. On the other hand, dimethylether was removed to a lower extent, although its reduced environmental impact allows to conclude that these results were satisfactory. PMID:17967474

Prado, O J; Veiga, M C; Kennes, C

2008-02-01

171

CO(2) capture from dilute gases as a component of modern global carbon management.  

PubMed

The growing atmospheric CO(2) concentration and its impact on climate have motivated widespread research and development aimed at slowing or stemming anthropogenic carbon emissions. Technologies for carbon capture and sequestration (CCS) employing mass separating agents that extract and purify CO(2) from flue gas emanating from large point sources such as fossil fuel-fired electricity-generating power plants are under development. Recent advances in solvents, adsorbents, and membranes for postcombust- ion CO(2) capture are described here. Specifically, room-temperature ionic liquids, supported amine materials, mixed matrix and facilitated transport membranes, and metal-organic framework materials are highlighted. In addition, the concept of extracting CO(2) directly from ambient air (air capture) as a means of reducing the global atmospheric CO(2) concentration is reviewed. For both conventional CCS from large point sources and air capture, critical research needs are identified and discussed. PMID:22432609

Jones, Christopher W

2011-01-01

172

Partitioning and removal of dioxin-like congeners in flue gases treated with activated carbon adsorption  

Microsoft Academic Search

Activated carbon adsorption is commonly used to control dioxin-like congener (PCDD\\/Fs and PCBs) emissions. Partitioning of PCDD\\/Fs and PCBs between vapor and solid phases and their removal efficiencies achieved with existing air pollution control devices (APCDs) at a large-scale municipal waste incinerator (MWI) and an industrial waste incinerator (IWI) are evaluated via intensive stack sampling and analysis. Those two facilities

Kai Hsien Chi; Shu Hao Chang; Chia Hua Huang; Hung Chi Huang; Moo Been Chang

2006-01-01

173

Analysis of PD-generated SF6 decomposition gases adsorbed on carbon nanotubes  

Microsoft Academic Search

Chemical byproducts analysis has been recognized as a powerful diagnosis method for SF6 gas-insulated switchgear (GIS). The authors have previously demonstrated that a carbon nanotube (CNT) gas sensor could detect partial discharge (PD) generated in SF6 gas. However, PD-generated decomposition gas species, which were responsible for the CNT gas sensor response, have not been identified yet. In this paper, two

Weidong Ding; Ryota Hayashi; Kohei Ochi; Junya Suehiro; Kiminobu Imasaka; Masanori Hara; Noriaki Sano; Eiichi Nagao; Tadao Minagawa

2006-01-01

174

Assessment of trace gases, carbon and nitrogen emissions from field burning of agricultural residues in India  

Microsoft Academic Search

Field burning of crop residue (FBCR) is becoming a growing environmental concern in developing countries. In this instance,\\u000a a comprehensive crop-wise and spatially distributed study on the FBCR emissions from India for the period 1980 through 2010\\u000a have been undertaken, that covers: residue generation, its types, use pattern, and estimates of carbon, nitrogen, CH4, CO, N2O and NOX emissions; along

Shivraj Sahai; C. Sharma; S. K. Singh; Prabhat K. Gupta

2011-01-01

175

Comparison of Upright Carbon Nanotwists Treated by Plasma with Different Types of Gases  

NASA Astrophysics Data System (ADS)

Carbon nanotwist (CNTw) is a kind of helical carbon nanofiber and a good candidate for field emission material as well as carbon nanotube. We have used CNTws as a base material of field emitter (FE). CNTws were synthesized by catalytic chemical vapor deposition [1]. The CNTw paste was prepared by mixing CNTw with an organic binder. The CNTw FE was fabricated by screen-printing the paste on substrates. Then, the FE surface was treated with plasma. A quartz plate was glued on both electrode surfaces of the plasma reactor. A glow discharge was generated uniformly in He gas, and dielectric barrier discharge (DBD) was generated in N2 gas. Three effects on the CNTw dots by DBD are shown as follows: (i) making CNTws stand up, (ii) relocation of CNTws, and (iii) etching of CNTws. By contrast, the three effects were not obtained by glow discharge. Luminescence from phosphor on the anode of the CNTw FE treated by DBD for 30 s was uniform. FE characteristics were improved by an increase of upright CNTws [2].[4pt] [1] Y. Hosokawa, et al, Res. Lett. Mater. Sci., 2007, 59167, 2007[0pt] [2] Y. Hosokawa, et al, J. Phys. D: Appl. Phys., 41, 205418, 2008

Suda, Yoshiyuki; Sugioka, Yuki; Takikawa, Hirofumi; Tanoue, Hideto; Ue, Hitoshi; Shimizu, Kazuki; Umeda, Yoshito

2011-11-01

176

Determination of carbon monoxide, methane and carbon dioxide in refinery hydrogen gases and air by gas chromatography.  

PubMed

This paper illustrates a method for determining trace amounts of CO, CH4 and CO2 with the detection limit of 0.15, 0.15 and 0.20 microg/l, respectively, in refinery hydrogen gases or in air. A simple modification of a gas chromatograph equipped with a flame-ionization detector is presented. A Porapak Q column, additionally connected with a short molecular sieve 5A packed column and a catalytic hydrogenation reactor on the Ni catalyst have been applied. The principle of the analytical method proposed is the separation of CO from O2 before the introduction of CO to the methanizer. The analytical procedure and examples of the results obtained have been presented. The modification applied makes it possible to use the GC instrument for other determinations, requiring utilization of the Porapak Q column and the flame-ionization detector. In such cases, the short molecular sieve 5A column and the methanizer can be by-passed. PMID:12650260

Kami?ski, Marian; Kartanowicz, Rafal; Jastrzebski, Daniel; Kami?ski, Marcin M

2003-03-14

177

Biosynthesis of 2-hydroxyisobutyric acid (2-HIBA) from renewable carbon  

Microsoft Academic Search

Nowadays a growing demand for green chemicals and cleantech solutions is motivating the industry to strive for biobased building blocks. We have identified the tertiary carbon atom-containing 2-hydroxyisobutyric acid (2-HIBA) as an interesting building block for polymer synthesis. Starting from this carboxylic acid, practically all compounds possessing the isobutane structure are accessible by simple chemical conversions, e. g. the commodity

Thore Rohwerder; Roland H Müller

2010-01-01

178

Greenhouse Gases  

MedlinePLUS

... are greenhouse gases? Many chemical compounds present in Earth's atmosphere behave as 'greenhouse gases'. These are gases ... direct sunlight (relative shortwave energy) to reach the Earth's surface unimpeded. As the shortwave energy (that in ...

179

Studies of the Terrestrial Molecular Oxygen and Carbon Cycles in Sand Dune Gases and in Biosphere 2.  

NASA Astrophysics Data System (ADS)

Molecular oxygen in the atmosphere is coupled tightly to the terrestrial carbon cycle by the processes of photosynthesis, respiration, and burning. This dissertation examines different aspects of this coupling in four chapters. Chapter 1 explores the feasibility of using air from sand dunes to reconstruct atmospheric O_2 composition centuries ago. Such a record would reveal changes in the mass of the terrestrial biosphere, after correction for known fossil fuel combustion, and constrain the fate of anthropogenic CO_2. Test drilling in sand dunes shows that sand dunes do contain old air, as shown by the concentrations of chlorofluorocarbons and ^{85}Kr. Diffusion is shown to dominate mixing rather than advection. However, biological respiration in dunes corrupts the signal, and isotopic analysis of O_2 and N _2 shows that fractionation of the gases precludes use of sand dunes as archives. Chapter 2 further explores this fractionation, revealing a previously unknown "water vapor flux fractionation" process. A flux of water vapor out of the moist dune into the dry desert air sweeps out the other gases, forcing them to diffuse back into the dune. The heavy isotopes of N_2 and O_2 diffuse more slowly, creating a steady state depletion of heavy isotopes in the dune interior. Molecular diffusion theory and a laboratory simulation of the effect agree well with the observations. Additional fractionation of the dune air occurs via thermal diffusion and gravitational settling, and it is predicted that soil gases in general will enjoy all three effects. Chapter 3 examines the cause of a mysterious drop in O _2 concentrations in the closed ecosystem of Biosphere 2, located near Tucson, Arizona. The organic -rich soil manufactured for the experiment is shown to be the culprit, with CO_2 produced by bacterial respiration of the organic matter reacting with the extensive concrete surfaces inside. Chapter 4 examines the O_2:C stoichiometry of terrestrial soil respiration and photosynthesis, in the context of using atmospheric O_2 measurements to constrain the size of the "missing sink" of CO_2. Direct measurements of soil respiration and biomatter elemental abundance suggest a value of 1.1 +/- 0.05 oxygen molecules per CO_2 molecule.

Severinghaus, Jeffrey Peck

180

Separation of polar gases from nonpolar gases  

DOEpatents

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

Kulprathipanja, S.; Kulkarni, S.S.

1986-08-26

181

Separation of polar gases from nonpolar gases  

DOEpatents

Polar gases such as hydrogen sulfide, sulfur dioxide and ammonia may be separated from nonpolar gases such as methane, nitrogen, hydrogen or carbon dioxide by passing a mixture of polar and nonpolar gases over the face of a multicomponent membrane at separation conditions. The multicomponent membrane which is used to effect the separation will comprise a mixture of a glycol plasticizer having a molecular weight of from about 200 to about 600 and an organic polymer cast on a porous support. The use of such membranes as exemplified by polyethylene glycol and silicon rubber composited on polysulfone will permit greater selectivity accompanied by a high flux rate in the separation process.

Kulprathipanja, Santi (Hoffman Estates, IL) [Hoffman Estates, IL; Kulkarni, Sudhir S. (Hoffman Estates, IL) [Hoffman Estates, IL

1986-01-01

182

Removal of gases by thermal-acid leached kaolinitic clays: Influence of mineralogical composition  

Microsoft Academic Search

Natural and modified kaolinitic clays were used as retention for gas adsorptions. The kaolinitic clays containing different mineralogical compositions were used. The modifications were carried out by heating the clays at 600 °C and then by acid treatment with 2.5 mol\\/L sulphuric acid solution at boiling temperature for 180 min. Equilibrium adsorption was measured using a volumetric apparatus, at 25

Cristina Volzone; José Ortiga

2006-01-01

183

Global distribution of column carbon dioxide and methane retrieved from observations of Greenhouse gases Observing SATellite (GOSAT)  

NASA Astrophysics Data System (ADS)

The Greenhouse gases Observing SATellite (GOSAT) was launched on January 23, 2009. The main target of the GOSAT observation is to obtain global distribution and variation of carbon dioxide and methane abundances. Thermal And Near infrared Sensor for carbon Observation-Fourier Transform Spectrometer (TANSO-FTS) detects the signal of reflected solar light on the earth's surface in Short Wavelength Infra-Red (SWIR) regions as well as that of radiance emitted from the surface and the atmosphere in Thermal Infra-Red (TIR) region. TANSO-Cloud and Aerosol Imager (TANSO-CAI) is a CCD radiometer to obtain the information on cloud and aerosols that contaminate the FTS signals. Since June 2009, TANSO-FTS and CAI have made continuous observation. Retrievals of carbon dioxide and methane column abundances from SWIR spectra for cloud-free scenes are retrieved in several processing versions. Optically thick clouds within the field of view of TANSO-FTS (approximately 10 km diameter) are detected using the TANSO-CAI radiances and optically thin cirrus using the solar reflected spectrum in the strong water vapor absorption band in the TANSO-FTS 2.0 m band. We applied an optimal estimation method (maximum a posteriori method) to the selected cloud-free scene data for retrieving column abundances of carbon dioxide and methane. Version 050.050 and version 080.080 of Level 1B products (four band spectra from TANSO-FTS and four band images from TANSO-CAI) have been open to the registered public users from late October 2009. Version 00.50 and 00.80 of Level 2 products (carbon dioxide and methane column abundances from TANSO-FTS SWIR and cloud flag from TANSO-CAI) have been opened to the registered public users from mid February 2010. At present, retrieved column abundances seem to be slightly underestimated, but global column-averaged concentration patterns and seasonal variations agree with the current knowledge. The retrieval algorithm will be improved soon.

Yokota, Tatsuya; Yoshida, Yukio; Morino, Isamu; Uchino, Osamu; Maksyutov, Shamil; Watanabe, Hiroshi

184

Characterization of carbon black modified by maleic acid  

NASA Astrophysics Data System (ADS)

We present here a method for modifying the surface of carbon black (CB) using a simple heat treatment in the presence of a carboxylic acid as well as water or ethylene glycol as a solvent. CB was mixed with maleic acid and either water or ethylene glycol, and heated at 250°C. Unlike the traditional surface modification processes which use heat treatment of carbon with mineral acids the present modification method using a carboxylic acid proved to be simple and time efficient. CB from two different vendors was used, and the modified samples were characterized by TGA, BET surface area measurement, XRD, particle size and zeta potential measurements, and FTIR. It was found that several material properties, including thermal stability and surface area, of the modified CB are significantly altered relative to the parental carbon samples. This method provides a rapid and simple route to tailor new materials with desired properties.

Asokan, Vijayshankar; Kosinski, Pawel; Skodvin, Tore; Myrseth, Velaug

2013-09-01

185

Evaluation of acidity of strong acid catalysts. 1. Derivation of an acidity function from carbon-13 NMR measurements  

Microsoft Academic Search

The limitations of the Hammett indicator method for acidity measurements of liquid acid catalysts of practical importance and the inapplicability in principle of the Hammett acidity concept to solid acid catalysts are discussed. Evaluation of acidities from the hydronation equilibrium of two simple alcohols, methanol and ethanol, and an α,β-unsaturated detone, 4-methyl-3-penten-2-one (mesityl oxide, I), by carbon-13 NMR is demonstrated

D. Farcasiu; A. Ghenciu; G. Miller

1992-01-01

186

A Pilot-Scale Evaluation of a New Technology to Control NO(x) Emissions from Boilers at KSC: Hydrogen Peroxide Injection into Boiler Flue Gases Followed by Wet Scrubbing of Acid Gases  

NASA Technical Reports Server (NTRS)

Emissions of nitrogen oxides NO(x) are a significant problem in the United States. NO(x) are formed in any combustion process, therefore it is not surprising that NO(x) are emitted from the boilers at KSC. Research at UCF has shown (in the laboratory) that injecting H2O2 into hot simulated flue gases can oxidize the NO and NO2 to their acid gas forms, HNO2 and HNO3, respectively. These acid gases are much more water soluble than their counterparts, and theoretically can be removed easily by wet scrubbing. This technology was of interest to NASA, both for their boilers at KSC, and for their combustion sources elsewhere. However, it was necessary to field test the technology and to provide pilot-scale data to aid in design of full-scale facilities. Hence this project was initiated in May of 1996.

Cooper, C. David

1997-01-01

187

Understanding the fluvial loss of carbon from UK watersheds - implications for terrestrial carbon; greenhouse gases and water quality  

NASA Astrophysics Data System (ADS)

This study develops a number of methods for estimating the fate of fluvial carbon through UK watersheds. The study considers dissolved organic carbon (DOC); particulate organic carbon (POC); and dissolved CO2. The study considers the loss from the terrestrial source; in-stream losses and production; and export to the continental shelf. The study used multiple approaches, including: mass balance studies; modelling and experimentation. i) Mass balance studies suggest that the UK losses 5 Mtonnes C/yr (21.8 tonnes C/km2/yr) from soils in the proportion of 7:22:4 (POC:DOC:diss. CO2). The mass balance studies suggest 3.5 Mtonnes C/yr (15.2 tonnes C/km2/yr) is lost to the atmosphere in the proportion 8:75:17 (POC:DOC:diss. CO2). ii) UK rivers have short residence times (typically 1-2 days) and so the diurnal cycle becomes critical. Experiments show that turnover rates are close to zero overnight but that these can be periods of DOC production from turnover of POC. iii) Development and modelling using physical rate showed that the loss of the DOC was between 24 and 37% - lower than that estimated from mass balance studies, but that the loss rate of TOC (DOC + POC) was between 57 and 80% - close to that estimated from mass balance studies. iv) Studies of molecular change suggest that nutrient supply is the limiting factor on turnover and that a position of 'pseudo-equilibirum' is achieved that limits the net effect of the fluvial processes.

Worrall, F.; Moody, C.; Burt, T. P.; Howden, N. J.

2013-12-01

188

High frequency response of carbon nanotube thin film speaker in gases  

NASA Astrophysics Data System (ADS)

The thermoacoustic response of carbon nanotube (CNT) thin films at frequencies ranging from 300 Hz up to 100 kHz has been studied in a variety of gaseous mediums. Theoretical derivations show that the sound pressure generated by CNT thin films is approximately proportional to the inverse of the heat capacity of the gas within the audible frequency range of human hearing, which is consistent with the experimental results in argon, air, and helium. For large size CNT films, a decrease in sound pressure is observed within a higher frequency range in air, which is attributed to the destructive interference of sound waves in the near field zone according to the theoretical calculations.

Xiao, Lin; Liu, Peng; Liu, Liang; Li, Qunqing; Feng, Zhenghe; Fan, Shoushan; Jiang, Kaili

2011-10-01

189

Fragrance material review on carbonic acid, methyl phenylmethyl ester.  

PubMed

A toxicologic and dermatologic review of carbonic acid, methyl phenylmethyl ester when used as a fragrance ingredient is presented. Carbonic acid, methyl phenylmethyl ester is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for carbonic acid, methyl phenylmethyl ester were evaluated, then summarized, and includes: physical properties, acute toxicity, skin irritation, and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414647

McGinty, D; Letizia, C S; Api, A M

2012-09-01

190

Robust IR Remote Sensing Technique of the Total Column of Trace Gases Including Carbon Dioxide and Methane  

NASA Technical Reports Server (NTRS)

Progress on the development of a differential radiometer based upon the Fabry-Perot interferometer (FPI) for methane (CH4) and carbon dioxide (C02) detection in the atmosphere is presented. Methane measurements are becoming increasingly important as a component of NASA's programs to understand the global carbon cycle and quantifY the threat of global warming. Methane is the third most important greenhouse gas in the Earth's radiation budget (after water vapor and carbon dioxide) and the second most important anthropogenic contributor to global warming. The importance of global warming and air quality to society caused the National Research Council to recommend that NASA develop the following missions [1]: ASCENDS (Active Sensing of C02 Emissions over Nights, Days, and Seasons), GEOCAPE (Geostationary Coastal and Air Pollution Events), and GACM (Global Atmosphere Composition Mission). Though methane measurements are not specifically called out in these missions, ongoing environmental changes have raised the importance of understanding the methane budget. In the decadal survey is stated that "to close the carbon budget, we would also address methane, but the required technology is not obvious at this time. If appropriate and cost-effective methane technology becomes available, we strongly recommend adding a methane capability". In its 2007 report the International Panel on Climate Change identified methane as a key uncertainty in our understanding saying that the causes of recent changes in the growth rate of atmospheric CH4 are not well understood. What we do know is that methane arises from a number of natural sources including wet lands and the oceans plus man made sources from agriculture, as well as coal and petroleum production and distribution. It has recently been pointed out that large amount of methane are frozen in the permafrost of Canada and Siberia. There is a fear that melting of this permafrost driven by global warming may release large amounts of methane very suddenly further exacerbating climate change [2]. Last year our group began a joint effort with Johns Hopkins Applied Physics Laboratory to investigate the possibility of developing a small unmanned aerial vehicle (UAV) equipped to measure greenhouse gases-particularly methane. Although we are targeting our system for smaller UAV's the instrument will be directly applicable to missions involving larger NASA UAV's such as Global Hawk or even on missions utilizing manned aircraft. Because of its small size, inherent ruggedness and simplicity some version of our proposed instrument may find a role as a satellite instrument for NASA or NOAA.

Georgieva, E. M.; Heaps, W. S.

2011-01-01

191

Quantum cascade laser absorption sensor for carbon monoxide in high-pressure gases using wavelength modulation spectroscopy.  

PubMed

A tunable quantum cascade laser sensor, based on wavelength modulation absorption spectroscopy near 4.8 ?m, was developed to measure CO concentration in harsh, high-pressure combustion gases. The sensor employs a normalized second harmonic detection technique (WMS-2f/1f) at a modulation frequency of 50 kHz. Wavelength selection at 2059.91??cm?¹ targets the P(20) transition within the fundamental vibrational band of CO, chosen for absorption strength and relative isolation from infrared water and carbon dioxide absorption. The CO spectral model is defined by the Voigt line-shape function, and key line-strength and line-broadening spectroscopic parameters were taken from the literature or measured. Sensitivity analysis identified the CO-N? collisional broadening coefficient as most critical for uncertainty mitigation in hydrocarbon/air combustion exhaust measurements, and this parameter was experimentally derived over a range of combustion temperatures (1100-2600 K) produced in a shock tube. Accuracy of the wavelength-modulation-spectroscopy-based sensor, using the refined spectral model, was validated at pressures greater than 40 atm in nonreactive shock-heated gas mixtures. The laser was then free-space coupled to an indium-fluoride single-mode fiber for remote light delivery. The fiber-coupled sensor was demonstrated on an ethylene/air pulse detonation combustor, providing time-resolved (~20??kHz), in situ measurements of CO concentration in a harsh flow field. PMID:24663473

Spearrin, R M; Goldenstein, C S; Jeffries, J B; Hanson, R K

2014-03-20

192

40 CFR 60.52b - Standards for municipal waste combustor metals, acid gases, organics, and nitrogen oxides.  

Code of Federal Regulations, 2010 CFR

...gases, organics, and nitrogen oxides. 60.52b Section 60...gases, organics, and nitrogen oxides. (a) The limits for...facility any gases that contain cadmium in excess of the limits specified...d) The limits for nitrogen oxides are specified in...

2010-07-01

193

ACIDIC GASES AND AEROSOLS IN THE EASTERN AND WESTERN UNITED STATES  

EPA Science Inventory

The USEPA National Dry Deposition Network (NDDN) is designed to provide long-term estimates of acidic gas and aerosol concentrations, and associated fluxes, across the continental United States. nspection of data collected since 1988 shows species-dependent variability in atmosph...

194

Natural-Gas Catalytic Reduction of Nitric Oxide Tail Gases from Nitric Acid Production.  

National Technical Information Service (NTIS)

Tests were conducted on natural-gas catalytic reduction of tail-gas nitric oxides from nitric acid production; they took place at atmospheric pressure in a combined installation. In operation over 710 hrs the nickel-chromium foil showed sufficient thermal...

A. D. Tikhonenko M. N. Nabiev

1968-01-01

195

Sulfuric acid vapor and other cloud-related gases in the Venus atmosphere - Abundances inferred from observed radio opacity  

NASA Technical Reports Server (NTRS)

It is suggested that the absorbing characteristics of sulfuric acid vapor appear to reconcile what had been thought to be an inconsistency among measurements and deductions regarding the constituents of the Venus atmosphere and radio occultation, radar reflection, and radio emission measurements of its opacity. Laboratory measurements of sulfuric acid, sulfur dioxide, water vapor, and carbon dioxide are used to model relative contributions to opacity as a function of height in a way that is consistent with observations of the constituents and absorbing properties of the atmosphere. It is concluded that sulfuric acid vapor is likely to be the principal microwave absorber in the 30-50 km altitude range of the middle atmosphere of Venus.

Steffes, P. G.; Eshleman, V. R.

1982-01-01

196

Effect of Acid Gases on the Pigment Composition of the Leaves of Trees and Lawn Plants (Vliyanie Kislykh Gazov na Pigmentnyi Sostav Listev Drevesnykh i Gazonykh Rastenii).  

National Technical Information Service (NTIS)

The chlorophyll a and b, carotene, lutein, violaxanthin, and neoxanthin contents in the leaves of plants, subjected during various phases of their growth and development to acid gases such as SO2, NO2, F, HF, and P2O5 in various concentrations, were studi...

V. V. Suslova V. S. Nikoloevskii

1971-01-01

197

Research and development on membrane processes for removal of acid gases during coal gasification. Final report, 20 June 1975-19 October 1976  

Microsoft Academic Search

The object of this program was to develop novel and unique membranes for separating acid gases from coal gasification streams. Many candidate membranes, including cationic, hydrophilic, and silicone, were tested. Optimum separation properties were possessed by membranes formulated from crosslinked methyl cellulose coated on polysulfone support films. The observed separation properties were explained theoretically by the solubility of the various

R. J. Petersen; J. E. Cadotte; E. J. Conway; R. H. Forester; M. J. Steuck

1976-01-01

198

Abundance and isotope systematics of carbon in subglacial basalts, geothermal gases and fluids from Iceland's rift zones  

NASA Astrophysics Data System (ADS)

P. H. BARRY1*, D. R. HILTON1, E. FÜRI1, S.A. HALLDÓRSON1, T.P. FISCHER2, K. GRONVOLD3 1 Scripps Institution of Oceanography, UCSD, La Jolla, California 92093, USA (*Correspondence: pbarry@ucsd.edu). 2University of New Mexico, Albuquerque, NM 87131, USA. 3University of Iceland, Askja, Sturlugata 7, IS-101, Reykjavik, Iceland Carbon dioxide (CO2) is the dominant non-aqueous volatile species found in oceanic basalts and geothermal fluids and serves as the carrier gas for trace volatiles such as He and other noble gases. The aim of this study is to identify the superimposed effects of degassing and crustal contamination on the CO2 systematics of the Icelandic hotspot in order to reveal and characterize the carbon abundance and isotopic features of the underlying mantle source. Our approach involves coupling CO2 with He, utilizing the sensitivity of 3He/4He ratios to reveal mantle and crustal inputs. We report new C-isotope (?13C) and abundance characteristics for a suite of 47 subglacial basalts and 50 geothermal gases and fluids from Iceland. CO2 contents in hyaloclastite glasses are extremely low (10-100 ppm) and likely residual following extensive degassing whereas geothermal fluids are dominated by CO2 (>90 %). C-isotopes range from -27.2 to -3.6 ‰ (vs. PDB) for basalts and from -18.8 to 2.86 ‰ (vs. PDB) for geothermal samples (mean = -4.2 ± 3.6 ‰). CO2/3He ratios range from 108 to 1012 for basalts and from 105 to 1012 for geothermal samples: In both cases, our results extend He-CO2 relationships over a much broader range than reported previously [1]. Taken together, these data suggest that several processes including mixing, degassing, and/or syn- or post-eruptive crustal contamination may act to modify CO2 source characteristics. Equilibrium degassing models are compatible with ~75 % of the basalt data, and preliminary results indicate that initial Icelandic source characteristics are ~500 ppm CO2 and ?13C ~ -5 ‰ (vs. PDB). These values are high compared to N-MORB mantle source estimates (72-134 ppm) based upon CO2/Nb ratios [2, 3]; however, they are in good agreement with those from submarine glasses on adjacent segments from the Reykjanes and Kolbeinsey ridges [4,5]. Significantly, the model-derived ?13C estimate is close to the mean Icelandic geothermal value, implying that fluids closely resemble source values, i.e. they likely represent the exsolved component. Integrating the estimated source CO2 content with magma production values of 0.079 km3/yr [6] yields a CO2 flux of ~1.2 x 1011 mol CO2 yr-1for Iceland, representing ~ 5.4 % of the total carbon ridge flux of 2.2 x 1012 mol CO2 yr-1 [7]. Thus, the average CO2 flux estimate for Iceland is ~2.2 x 108 mol CO2 yr-1km-1 strike of ridge axis, which compares to an overall ridge flux (including Iceland) of ~2.9 x 107 mol CO2 yr-1km-1. This difference highlights both heterogeneity in source volatile contents and magma production rates as important controls for determining mantle CO2 fluxes. [1] Poreda et al., 1992 [2] Saal et al., 2002. [3] Shaw et al., 2010. [4] de Leeuw, 2007 [5] Macpherson et al., 2005. [6] Thordarson et al., 2007 [7] Marty et al., 1998.

Barry, P. H.; Hilton, D. R.; Fueri, E.; Halldorsson, S. A.; Fischer, T. P.; Gronvold, K.

2010-12-01

199

Helium and carbon isotope systematics of Rungwe geothermal gases and fluids; southern Tanzania  

NASA Astrophysics Data System (ADS)

P. H. BARRY1*, D. R. HILTON1, T. P. FISCHER2, J. M. DE MOOR2, F. MANGASINI3 C. RAMIREZ4 1 Geosciences Research Division, Scripps Institution of Oceanography, UCSD, La Jolla, California 92093-0244, USA (*Correspondence: pbarry@ucsd.edu) 2 Department of Earth and Planetary Sciences, MSC 03 2040, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, USA. 3 Department of Mining and Mineral Processing Engineering, University of Dar Es Salaam, PO Box 35131, Dar Es Salaam, Tanzania. 4 Centro de Investigaciones en Ciencias Geologicas, Escuela Centroamericana de Geologia, Universidad de Costa Rica. The East African Rift (EAR) is the largest modern example of continental rifting, extending from the Afar depression in the north to the Rungwe region in southern Tanzania. EAR volcanism is attributed to the presence of one or more mantle plumes [1]. Late Miocene to recent volcanism and geothermal activity mark the Rungwe region [2], with mafic eruptions as recently as 200 years ago. Our aim is to delineate the southern geographical extent of plume influence on the propagating EAR by investigating the He-CO2 characteristics of geothermal fluids in the Rungwe region. We report new helium (He) and carbon (C) isotopes (3He/4He, ?13C) and relative abundance (CO2/3He) characteristics for a suite of 20 geothermal gas and fluid samples from 11 different localities in the Rungwe region. He-isotopes are in good agreement with previous reports [3], and range from ~1 RA to ~7 RA (MORB-like values), indicating admixture between upper mantle He and variable proportions of radiogenic He. C-isotopes ranges from -2.8 to -6.5 ‰ (vs. PDB) with all falling in the MORB range (~4.5 ± 2‰). CO2/3He ratios vary over 5 orders of magnitude from ~3 x 10^9 (MORB-like) to higher values (up to ~3 x 10^13) normally associated with crustal lithologies. Taken together, the He-CO2 data can be explained by 2-component mixing of a deep-seated mantle source with crustal component(s). There are no observed latitudinal isotopic trends in He-CO2. However, the two localities with MORB-like 3He/4He ratios ~6 to 7 RA, ?13C ~ -4 to -5 ‰ and CO2/3He ~ 4 x10^9 are both cold temperature (~ 15°C) CO2 gas vents. The MORB-like characteristics of these cold vents are comparable to MORB-like values observed at Oldoinyo Lengai in northern Tanzania [4], suggesting that both Rungwe region and Oldoinyo Lengai may derive their volatile compositions from a homogeneous (MORB-like) mantle source common to the entire segment of the southern EAR. [1] Furman (2007) Journal of African Earth Sciences 48, 147-160. [2] Ebinger et al. (1989) Journal of Geophysical Research 94, 15,785-15,803. [3] Pik et al. (2006) Chemical Geology 226, 100-114. [4] Fisher et al. (2009) Nature 459, 77-80.

Barry, P. H.

2009-12-01

200

ANALYSIS OF COMMERCIAL CYLINDER GASES OF NITRIC OXIDE, SULFUR DIOXIDE, AND CARBON MONOXIDE AT SOURCE CONCENTRATIONS: RESULTS OF AUDIT 5  

EPA Science Inventory

Manufacturers of commercial cylinder gases supply standards with a certified analysis and a statement of accuracy. Generally, the level of accuracy is specified as a percentage of the component value. To ascertain the accuracy of analyses of commercially available cylinder gases,...

201

A mechanistic model of wormhole growth in carbonate matrix acidizing and acid fracturing  

SciTech Connect

A mathematical model that describes the growth and competition of wormholes during ann acidizing treatment in a carbonate formation was developed. The model is initialized with the distribution of largest pores. Wormhole characteristics (size, length, and distribution) were found too be controlled by acid-injection, diffusion, and fluid-loss rates.

Hung, K.M.; Hill, A.D.; Sepehrnoorl, K.

1989-01-01

202

Theoretical estimates of equilibrium 13C-18O clumping in carbonates and organic acids  

NASA Astrophysics Data System (ADS)

The development of techniques for measuring small gas-phase molecules containing more than one rare stable isotope (e.g., 13C18O16O) at natural, ppm-level abundances1,2 has made it possible to track sources and sinks of atmospheric gases from a new perspective. Similar measurements of 13C-18O clumping in ancient samples could improve our understanding of ancient climates, if the abundances of `clumped' rare stable isotopes in materials that retain isotopic signatures over geologic time can be measured with sufficient precision. This theoretical study estimates the abundances of such 13C-18O `clumps' in carbonates and organic acids and discusses their potential applications. Accompanying abstracts by Eiler et al. and Ghosh et al. will present the analytical methods and some initial data for carbonate minerals to examine the applicability of our theoretical models. Equilibrium isotopic speciations in carbonate minerals and organic acids are calculated from the reduced partition function ratios of isotopically substituted crystals and molecules. Vibrational frequencies used as input for these calculations come from ab initio force fields, determined using density functional theory. Our calculations indicate that carbonate minerals, including calcite, dolomite, and aragonite, when equilibrated at earth-surface temperatures, will have a slight overabundance of CO32- groups containing both 13C and 18O (i.e., 13C18O16O22-) relative to what would be expected if carbon and oxygen isotopes were distributed randomly in the crystal lattice. Calcite and dolomite crystals are predicted to have 0.4‰ excesses of 13C18O16O22- at 298 K; in aragonite the excess will be about 0.05‰ larger. The excesses are smaller for crystals formed or equilibrated at higher temperatures, decreasing by 0.003\\permil/oC at room temperature and essentially disappearing at temperatures of 1000 K or higher. Similarly, there is an excess of both 13C18O16OH and 13C16O18OH groups in organic acids like formic acid (HCOOH) and pyruvic acid (CH3COCOOH) that equilibrate at low temperatures. For gas-phase carboxylic acids, 13C-18O clumping in the COOH group is strongest at the C=O double bond, with an 1.0-1.1‰ excess at room temperature. The C-O-H subgroup has an ~0.4‰ 13C-18O excess, and thus the average anomaly for the whole COOH group is 0.7-0.8\\permil. As with carbonate minerals, these excesses decrease at higher temperatures. The magnitude of 13C-18O clumping in carboxylic acid is similar to gas-phase CO2 1,2,3, while in carbonate minerals the effect is about one-half as large. The temperature sensitivity of these isotopic clumping effects suggests that measurements of abundances of 13C-18O bonds in carbonates and organic acids could be useful for paleothermometry. The clumping equilibrium is an internal property of each phase, so temperature information can be obtained even when the isotopic composition of the fluid phase from which a sample precipitated is unknown. Clumping effects may also be able to distinguish pristine, unaltered sedimentary and biogenic carbonates and organic deposits from those that have undergone post-depositional diagenesis or metamorphism, even in samples that have not suffered extensive open-system exchange. Refs: 1Eiler et al. 2004, GCA in press; 2Schauble et al. in prep.; 3Wang et al. 2004, GCA in press.

Schauble, E. A.; Eiler, J. M.

2004-12-01

203

Collection of VLE data for acid gas---alkanolamine systems using fourier transform infrared spectroscopy. Phase 2, October 1, 1991--September 30, 1992.  

National Technical Information Service (NTIS)

The industrial standard process for the purification of natural gas is to remove acid gases, mainly hydrogen sulfide and carbon dioxide, by the absorption and reaction of these gases with alkanolamines. Inadequate data for vapor--liquid equilibrium (VLE) ...

J. A. Bullin R. E. Frazier

1992-01-01

204

Collection of VLE data for acid gas-alkanolamine systems using Fourier transform infrared spectroscopy. Technical report, October 1, 1994--July 31, 1995.  

National Technical Information Service (NTIS)

The industrial standard process for the purification of natural gas is to remove acid gases, mainly hydrogen sulfide and carbon dioxide, by the absorption and reaction of these gases with alkanolamines. The natural gas industry requires vapor-liquid equil...

J. A. Bullin W. J. Rogers

1995-01-01

205

Surface functional groups on acid-activated nutshell carbons  

Microsoft Academic Search

Nutshells from agriculturally important nut crops (almond, black walnut, English walnut, macadamia nut and pecan) were converted to granular activated carbon using phosphoric acid activation in nitrogen or air. Surface functional groups (carbonyl, phenols, lactones, carboxyl) were quantified by titration with bases of different ionization potential. The degree of copper uptake was correlated with the presence of various functional groups

Christopher A. Toles; Wayne E. Marshall; Mitchell M. Johns

1999-01-01

206

ELEMENTAL MERCURY ADSORPTION BY ACTIVATED CARBON TREATED WITH SULFURIC ACID  

EPA Science Inventory

The paper gives results of a study of the adsorption of elemental mercury at 125 C by a sulfuric-acid (H2S04, 50% w/w/ solution)-treated carbon for the removal of mercury from flue gas. The pore structure of the sample was characterized by nitrogen (N2) at -196 C and the t-plot m...

207

Carbon edge XANES spectroscopy of amino acids and peptides  

Microsoft Academic Search

Carbon edge X-ray absorption near-edge structures (XANES) of amino acids and small peptides have been investigated for the first time. Because of the heat sensitivity of the samples, gas phase spectroscopy of evaporated samples is difficult. Therefore they were analyzed in solid form as thin films. Quantitative absorption measurements require the region of the sample which is illuminated to be

J Boese; A Osanna; C Jacobsen; J Kirz

1997-01-01

208

Volatile fatty acids as organic carbon sources in denitrification  

Microsoft Academic Search

We have evaluated the possibilities of waste water denitrification using volatile fatty acids (VFA) as the sole carbon and electron source in an activated sludge culture continuously fed with a mixture of acetate, propionate, butyrate and valerate. All the VFA were biodegraded in denitrification conditions by a mixed adapted bacterial population with 5 predominant different bacterial strains (Ochrobactrum anthropi, Moraxella

S. Fass; V. Ganaye; V. Urbain; J. Manem; J. C. Block

1994-01-01

209

Unusual stability and carbon acidity of a dicationic carbon species.  

PubMed

1,1'-Methylenebis(pyridinium) dication (MDP) is an unusual ion with two formal positively charged substituents attached to a central carbon, yet it is remarkably stable to hydrolysis at pH < 8. However, above this pH it undergoes a biphasic reaction liberating two equiv of pyridine sequentially. The rate of the first phase is second order in hydroxide ion, while that of the second is pH-independent. The first phase is also accompanied by the generation of a chromophore at 366 nm, which has been identified as a pyridine-ring-opened unsaturated iminoaldehyde formed by an ANRORC-type mechanism. This intermediate then undergoes ring closure to give the second equiv of pyridine and formaldehyde. Below pD 8 there is a very slow alternative pathway for degradation that is first order in hydroxide ion, liberates only one equiv of pyridine, and forms N-(hydroxymethyl)pyridinium ion. Deuterium exchange of the central methylene in D2O is faster than the breakdown of MDP and is predominantly OD(-)-catalyzed with a small amount of buffer catalysis. The estimated pKa of MDP dication in H2O, 21.2 at 25 °C and I = 1.0 M (KCl), is unexpectedly high but is about 9 units lower than that for the monocationic N-methylpyridinium ion. Deuterium exchange also occurs at the 2 and 6 positions of the pyridinium rings, but at a lower rate that is first order in deuteroxide ion and competitive with the breakdown of MDP only below pD 11. PMID:24059810

Mistry, Dharmit; Powles, Nicholas; Page, Michael I

2013-11-01

210

Synthesis and acid catalysis of cellulose-derived carbon-based solid acid  

NASA Astrophysics Data System (ADS)

SO 3H-bearing amorphous carbon, prepared by partial carbonization of cellulose followed by sulfonation in fuming H 2SO 4, was applied as a solid catalyst for the acid-catalyzed hydrolysis of ?-1,4 glucan, including cellobiose and crystalline cellulose. Structural analyses revealed that the resulting carbon material consists of graphene sheets with 1.5 mmol g -1 of SO 3H groups, 0.4 mmol g -1 of COOH, and 5.6 mmol g -1 of phenolic OH groups. The carbon catalyst showed high catalytic activity for the hydrolysis of ?-1,4 glycosidic bonds in both cellobiose and crystalline cellulose. Pure crystalline cellulose was not hydrolyzed by conventional strong solid Brønsted acid catalysts such as niobic acid, Nafion ® NR-50, and Amberlyst-15, whereas the carbon catalyst efficiently hydrolyzes cellulose into water-soluble saccharides. The catalytic performance of the carbon catalyst is due to the large adsorption capacity for hydrophilic reactants and the adsorption ability of ?-1,4 glucan, which is not adsorbed to other solid acids.

Suganuma, Satoshi; Nakajima, Kiyotaka; Kitano, Masaaki; Yamaguchi, Daizo; Kato, Hideki; Hayashi, Shigenobu; Hara, Michikazu

2010-06-01

211

Fullerenes: A New Carrier Phase for Noble Gases in Meteorites  

NASA Technical Reports Server (NTRS)

The major focus of our research effort has been to measure the noble gases encapsulated within fullerenes, a new carbon carrier phase and compare it to the myriad of components found in the bulk meteorite acid residues. We have concentrated on the carbonaceous chondrites (Allende, Murchison and Tagish Lake) since they have abundant noble gases, typically with a planetary signature that dominates the stepped-release of the meteorite bulk acid residue. They also contain an extractable fullerene component that can be isolated and purified from the same bulk material.

Becker, Luann

2004-01-01

212

Evaluation of acidity of strong acid catalysts. 1. Derivation of an acidity function from carbon-13 NMR measurements  

SciTech Connect

The limitations of the Hammett indicator method for acidity measurements of liquid acid catalysts of practical importance and the inapplicability in principle of the Hammett acidity concept to solid acid catalysts are discussed. Evaluation of acidities from the hydronation equilibrium of two simple alcohols, methanol and ethanol, and an {alpha},{beta}-unsaturated detone, 4-methyl-3-penten-2-one (mesityl oxide, I), by carbon-13 NMR is demonstrated for sulfuric acid-water mixtures. The latter compound is particularly useful because the signal for its carbon atom C-4 shifts downfield upon hydronation by almost 50 ppm, whereas the signal for C-3 moves upfield by 3 ppm. The comparison of the chemical shift difference {delta}(C-4)-{delta}(C-3) ({Delta}{delta}) for two different solutions allows a comparison of acidities of the two solutions from which other medium effects upon chemical shifts have been canceled out. The variation of {Delta}{delta} with concentration of I, or the ratio of base (I) to acid, is linear, at least between 1 and 0.5 M of I. Extrapolation of {Delta}{delta} of I to (B)/(AH) = 0 ({Delta}{delta}{sup 0}) allows the use of {sup 13}C NMR spectroscopy to establish a thermodynamically meaningful acidity scale, such as the traditional acidity function H{sub 0}. The slope of {Delta}{delta} vs (B)/(AH) plot changes with acid strength; it is lowest (most negative) for the acidity at which I is half-protonated. The acidity required for half-protonation can thus be accurately determined from this slope. On the other hand, {Delta}{delta} can be also measured at the stoichiometric ratio of the indicator base to acid molecules or sites. The latter approach must be used for comparison of strength of solid acids.

Farcasiu, D.; Ghenciu, A.; Miller, G. (Univ. of Pittsburgh, PA (United States))

1992-03-01

213

Butyric acid esterification kinetics over Amberlyst solid acid catalysts: the effect of alcohol carbon chain length.  

PubMed

The liquid phase esterification of butyric acid with a series of linear and branched alcohols is examined. Four strong cation exchange resins, Amberlyst™ 15, Amberlyst™ 36, Amberlyst™ BD 20, and Amberlyst™ 70, were used along with para-toluenesulfonic acid as a homogeneous catalyst. The effect of increasing alcohol carbon chain length and branching on esterification rate at 60°C is presented. For all catalysts, the decrease in turnover frequency (TOF) with increasing carbon chain length of the alcohol is described in terms of steric hindrance, alcohol polarity, and hydroxyl group concentration. The kinetics of butyric acid esterification with 2-ethylhexanol using Amberlyst™ 70 catalyst is described with an activity-based, pseudo-homogeneous kinetic model that includes autocatalysis by butyric acid. PMID:23380294

Pappu, Venkata K S; Kanyi, Victor; Santhanakrishnan, Arati; Lira, Carl T; Miller, Dennis J

2013-02-01

214

Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media.  

PubMed

The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40?°C, 0.2?M formic acid can be obtained under 200?bar, however, in DMSO the same catalyst affords 1.9?M formic acid. In both solvents the catalysts can be reused multiple times without a decrease in activity. Worldwide demand for formic acid continues to grow, especially in the context of a renewable energy hydrogen carrier, and its production from CO2 without base, via the direct catalytic carbon dioxide hydrogenation, is considerably more sustainable than the existing routes. PMID:24886955

Moret, Séverine; Dyson, Paul J; Laurenczy, Gábor

2014-01-01

215

Direct synthesis of formic acid from carbon dioxide by hydrogenation in acidic media  

PubMed Central

The chemical transformation of carbon dioxide into useful products becomes increasingly important as CO2 levels in the atmosphere continue to rise as a consequence of human activities. In this article we describe the direct hydrogenation of CO2 into formic acid using a homogeneous ruthenium catalyst, in aqueous solution and in dimethyl sulphoxide (DMSO), without any additives. In water, at 40?°C, 0.2?M formic acid can be obtained under 200?bar, however, in DMSO the same catalyst affords 1.9?M formic acid. In both solvents the catalysts can be reused multiple times without a decrease in activity. Worldwide demand for formic acid continues to grow, especially in the context of a renewable energy hydrogen carrier, and its production from CO2 without base, via the direct catalytic carbon dioxide hydrogenation, is considerably more sustainable than the existing routes.

Moret, Severine; Dyson, Paul J.; Laurenczy, Gabor

2014-01-01

216

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...

217

Karstification without carbonic acid: bedrock dissolution by gypsum- driven dedolomitization  

USGS Publications Warehouse

The primary karst-forming process at Lake Banyoles is dedolomitization of basement rocks driven by gypsum dissolution. Karstification takes place along the subsurface contact between the gypsiferous Beuda Formation and the dolomitic Perafita Formation. This process is here recognized for the first time to cause karstification on a large scale; this is significant because it proceeds without the addition of soil-generated carbonic acid. -from Authors

Bischoff, J. L.; Julia, R.; Shanks, W. C.; Rosenbauer, R. J.

1994-01-01

218

Adsorption of naphthenic acids on high surface area activated carbons.  

PubMed

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

Iranmanesh, Sobhan; Harding, Thomas; Abedi, Jalal; Seyedeyn-Azad, Fakhry; Layzell, David B

2014-07-01

219

Biosynthesis of 2-hydroxyisobutyric acid (2-HIBA) from renewable carbon.  

PubMed

Nowadays a growing demand for green chemicals and cleantech solutions is motivating the industry to strive for biobased building blocks. We have identified the tertiary carbon atom-containing 2-hydroxyisobutyric acid (2-HIBA) as an interesting building block for polymer synthesis. Starting from this carboxylic acid, practically all compounds possessing the isobutane structure are accessible by simple chemical conversions, e. g. the commodity methacrylic acid as well as isobutylene glycol and oxide. During recent years, biotechnological routes to 2-HIBA acid have been proposed and significant progress in elucidating the underlying biochemistry has been made. Besides biohydrolysis and biooxidation, now a bioisomerization reaction can be employed, converting the common metabolite 3-hydroxybutyric acid to 2-HIBA by a novel cobalamin-dependent CoA-carbonyl mutase. The latter reaction has recently been discovered in the course of elucidating the degradation pathway of the groundwater pollutant methyl tert-butyl ether (MTBE) in the new bacterial species Aquincola tertiaricarbonis. This discovery opens the ground for developing a completely biotechnological process for producing 2-HIBA. The mutase enzyme has to be active in a suitable biological system producing 3-hydroxybutyryl-CoA, which is the precursor of the well-known bacterial bioplastic polyhydroxybutyrate (PHB). This connection to the PHB metabolism is a great advantage as its underlying biochemistry and physiology is well understood and can easily be adopted towards producing 2-HIBA. This review highlights the potential of these discoveries for a large-scale 2-HIBA biosynthesis from renewable carbon, replacing conventional chemistry as synthesis route and petrochemicals as carbon source. PMID:20184738

Rohwerder, Thore; Müller, Roland H

2010-01-01

220

Biosynthesis of 2-hydroxyisobutyric acid (2-HIBA) from renewable carbon  

PubMed Central

Nowadays a growing demand for green chemicals and cleantech solutions is motivating the industry to strive for biobased building blocks. We have identified the tertiary carbon atom-containing 2-hydroxyisobutyric acid (2-HIBA) as an interesting building block for polymer synthesis. Starting from this carboxylic acid, practically all compounds possessing the isobutane structure are accessible by simple chemical conversions, e. g. the commodity methacrylic acid as well as isobutylene glycol and oxide. During recent years, biotechnological routes to 2-HIBA acid have been proposed and significant progress in elucidating the underlying biochemistry has been made. Besides biohydrolysis and biooxidation, now a bioisomerization reaction can be employed, converting the common metabolite 3-hydroxybutyric acid to 2-HIBA by a novel cobalamin-dependent CoA-carbonyl mutase. The latter reaction has recently been discovered in the course of elucidating the degradation pathway of the groundwater pollutant methyl tert-butyl ether (MTBE) in the new bacterial species Aquincola tertiaricarbonis. This discovery opens the ground for developing a completely biotechnological process for producing 2-HIBA. The mutase enzyme has to be active in a suitable biological system producing 3-hydroxybutyryl-CoA, which is the precursor of the well-known bacterial bioplastic polyhydroxybutyrate (PHB). This connection to the PHB metabolism is a great advantage as its underlying biochemistry and physiology is well understood and can easily be adopted towards producing 2-HIBA. This review highlights the potential of these discoveries for a large-scale 2-HIBA biosynthesis from renewable carbon, replacing conventional chemistry as synthesis route and petrochemicals as carbon source.

2010-01-01

221

An Investigation into the Gettering Powers of Various Metals for the Gases Hydrogen, Oxygen, Nitrogen, Carbon Dioxide and Air  

Microsoft Academic Search

Measurements of the ``gettering'' or clean-up ability of aluminum, magnesium, thorium, uranium, misch metal, zirconium and barium for the common gases were made. In most cases the measurements were quantitative and represent gettering powers unassisted by an electric discharge or other source of ions. The effect of temperature conditions on the gettering and keeping properties of several of the getters

Louis F. Ehrke; Charles M. Slack

1940-01-01

222

Amino acids of the Murchison meteorite. II - Five carbon acyclic primary beta-, gamma-, and delta-amino alkanoic acids  

NASA Technical Reports Server (NTRS)

The five-carbon acyclic primary beta, gamma, and delta amino alkanoic acids of the Murchison meteorite are studied using gas chromatography-mass spectrometry and ion exchange chromatography. The chromatograms reveal that alpha is the most abundant monoamino alkanoic acid followed by gamma and beta, and an exponential increase in the amount of amino acid is observed as the carbon number increases in the homologous series. The influence of frictional heating, spontaneous thermal decomposition, and radiation of the synthesis of amino acids is examined. The data obtained support an amino acid synthesis process involving random combination of single-carbon precursors.

Cronin, J. R.; Pizzarello, S.; Yuen, G. U.

1985-01-01

223

Deforestation and Greenhouse Gases.  

National Technical Information Service (NTIS)

Human activities produce large amounts of greenhouse gases (GHGs), primarily carbon dioxide (CO2), and thus contribute to global warming. The use of fossil fuels is the primary source of CO2 emissions, but the removal of trees from forested land has also ...

2012-01-01

224

Greenhouse Gases: A Closer Look  

NSDL National Science Digital Library

This lesson covers different aspects of the major greenhouse gases - water vapor, carbon dioxide, methane, nitrous oxides and CFCs - including some of the ways in which human activities are affecting the atmospheric concentrations of these key greenhouse gases. This is lesson six in a nine-lesson module about climate change.

Science, King'S C.

225

Electrochemical Determination of Glycoalkaloids Using a Carbon Nanotubes-Phenylboronic Acid Modified Glassy Carbon Electrode  

PubMed Central

A versatile strategy for electrochemical determination of glycoalkaloids (GAs) was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA) modified glassy carbon electrode. PBA reacts with ?-solanine and ?-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 ?M to 28 ?M and the detection limit was 0.3 ?M. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors.

Wang, Huiying; Liu, Mingyue; Hu, Xinxi; Li, Mei; Xiong, Xingyao

2013-01-01

226

Maintenance Carbon Cycle in Crassulacean Acid Metabolism Plant Leaves 1  

PubMed Central

The reciprocal relationship between diurnal changes in organic acid and storage carbohydrate was examined in the leaves of three Crassulacean acid metabolism plants. It was found that depletion of leaf hexoses at night was sufficient to account quantitatively for increase in malate in Ananas comosus but not in Sedum telephium or Kalanchoë daigremontiana. Fructose and to a lesser extent glucose underwent the largest changes. Glucose levels in S. telephium leaves oscillated diurnally but were not reciprocally related to malate fluctuations. Analysis of isolated protoplasts and vacuoles from leaves of A. comosus and S. telephium revealed that vacuoles contain a large percentage (>50%) of the protoplast glucose, fructose and malate, citrate, isocitrate, ascorbate and succinate. Sucrose, a major constituent of intact leaves, was not detectable or was at extremely low levels in protoplasts and vacuoles from both plants. In isolated vacuoles from both A. comosus and S. telephium, hexose levels decreased at night at the same time malate increased. Only in A. comosus, however, could hexose metabolism account for a significant amount of the nocturnal increase in malate. We conclude that, in A. comosus, soluble sugars are part of the daily maintenance carbon cycle and that the vacuole plays a dynamic role in the diurnal carbon assimilation cycle of this Crassulacean acid metabolism plant.

Kenyon, William H.; Severson, Ray F.; Black, Clanton C.

1985-01-01

227

Removal of Particles and Acid Gases (SO2 or HCl) with a Ceramic Filter by Addition of Dry Sorbents  

SciTech Connect

The present investigation intends to add to the fundamental process design know-how for dry flue gas cleaning, especially with respect to process flexibility, in cases where variations in the type of fuel and thus in concentration of contaminants in the flue gas require optimization of operating conditions. In particular, temperature effects of the physical and chemical processes occurring simultaneously in the gas-particle dispersion and in the filter cake/filter medium are investigated in order to improve the predictive capabilities for identifying optimum operating conditions. Sodium bicarbonate (NaHCO{sub 3}) and calcium hydroxide (Ca(OH){sub 2}) are known as efficient sorbents for neutralizing acid flue gas components such as HCl, HF, and SO{sub 2}. According to their physical properties (e.g. porosity, pore size) and chemical behavior (e.g. thermal decomposition, reactivity for gas-solid reactions), optimum conditions for their application vary widely. The results presented concentrate on the development of quantitative data for filtration stability and overall removal efficiency as affected by operating temperature. Experiments were performed in a small pilot unit with a ceramic filter disk of the type Dia-Schumalith 10-20 (Fig. 1, described in more detail in Hemmer 2002 and Hemmer et al. 1999), using model flue gases containing SO{sub 2} and HCl, flyash from wood bark combustion, and NaHCO{sub 3} as well as Ca(OH){sub 2} as sorbent material (particle size d{sub 50}/d{sub 84} : 35/192 {micro}m, and 3.5/16, respectively). The pilot unit consists of an entrained flow reactor (gas duct) representing the raw gas volume of a filter house and the filter disk with a filter cake, operating continuously, simulating filter cake build-up and cleaning of the filter medium by jet pulse. Temperatures varied from 200 to 600 C, sorbent stoichiometric ratios from zero to 2, inlet concentrations were on the order of 500 to 700 mg/m{sup 3}, water vapor contents ranged from zero to 20 vol%. The experimental program with NaHCO{sub 3} is listed in Table 1. In addition, model calculations were carried out based on own and published experimental results that estimate residence time and temperature effects on removal efficiencies.

Hemmer, G.; Kasper, G.; Wang, J.; Schaub, G.

2002-09-20

228

Dynamics of submarine groundwater discharge and associated fluxes of dissolved nutrients, carbon, and trace gases to the coastal zone (Okatee River estuary, South Carolina)  

USGS Publications Warehouse

Multiple techniques, including thermal infrared aerial remote sensing, geophysical and geological data, geochemical characterization and radium isotopes, were used to evaluate the role of groundwater as a source of dissolved nutrients, carbon, and trace gases to the Okatee River estuary, South Carolina. Thermal infrared aerial remote sensing surveys illustrated the presence of multiple submarine groundwater discharge sites in Okatee headwaters. Significant relationships were observed between groundwater geochemical constituents and 226Ra activity in groundwater with higher 226Ra activity correlated to higher concentrations of organics, dissolved inorganic carbon, nutrients, and trace gases to the Okatee system. A system-level radium mass balance confirmed a substantial submarine groundwater discharge contribution of these constituents to the Okatee River. Diffusive benthic flux measurements and potential denitrification rate assays tracked the fate of constituents in creek bank sediments. Diffusive benthic fluxes were substantially lower than calculated radium-based submarine groundwater discharge inputs, showing that advection of groundwater-derived nutrients dominated fluxes in the system. While a considerable potential for denitrification in tidal creek bank sediments was noted, in situ denitrification rates were nitrate-limited, making intertidal sediments an inefficient nitrogen sink in this system. Groundwater geochemical data indicated significant differences in groundwater chemical composition and radium activity ratios between the eastern and western sides of the river; these likely arose from the distinct hydrological regimes observed in each area. Groundwater from the western side of the Okatee headwaters was characterized by higher concentrations of dissolved organic and inorganic carbon, dissolved organic nitrogen, inorganic nutrients and reduced metabolites and trace gases, i.e. methane and nitrous oxide, than groundwater from the eastern side. Differences in microbial sulfate reduction, organic matter supply, and/or groundwater residence time likely contributed to this pattern. The contrasting features of the east and west sub-marsh zones highlight the need for multiple techniques for characterization of submarine groundwater discharge sources and the impact of biogeochemical processes on the delivery of nutrients and carbon to coastal areas via submarine groundwater discharge.

Porubsky, W. P.; Weston, N. B.; Moore, W. S.; Ruppel, C.; Joye, S. B.

2014-01-01

229

Comparison of the elimination between perfluorinated fatty acids with different carbon chain length in rats  

Microsoft Academic Search

Elimination in urine and feces was compared between four perfluorinated fatty acids (PFCAs) with different carbon chain length. In male rats, perfluoroheptanoic acid (PFHA) was rapidly eliminated in urine with the proportion of 92% of the dose being eliminated within 120 h after an intraperitoneal injection. Perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) was eliminated in urine

Naomi Kudo; Erika Suzuki; Masanori Katakura; Kohtaro Ohmori; Rie Noshiro; Yoichi Kawashima

2001-01-01

230

HEMP-derived activated carbon fibers by chemical activation with phosphoric acid  

Microsoft Academic Search

Activated carbon fibers were prepared by chemical activation of hemp fibers with phosphoric acid at different carbonization temperatures and impregnation ratios. Surface properties of the activated carbons fibers were significantly influenced by the activation temperature and the impregnation ratio. An increase of either of these parameters produced a high development of the porous structure of the fibers. Activated carbon fibers

J. M. Rosas; J. Bedia; J. Rodríguez-Mirasol; T. Cordero

2009-01-01

231

Greenhouse Gases  

MedlinePLUS

... were not for naturally occurring greenhouse gases, the Earth would be too cold to support life as ... the greenhouse effect, the average temperature of the Earth would be about -2°F rather than the ...

232

Gas chromatography for in situ analysis of a cometary nucleus. II. Analysis of permanent gases and light hydrocarbons with a carbon molecular sieve porous layer open tubular column  

NASA Astrophysics Data System (ADS)

Considering the severe constraints of space instrumentation, a great improvement for the in situ gas chromatographic (GC) determination of permanent and noble gases in a cometary nucleus is the use of a new carbon molecular sieve Porous Layer Open Tubular (PLOT) column called Carbobond. No exhaustive data dealing with this column being available, studies were carried out to entirely characterize its analytical performances, specially when used at the operating conditions of the COmetary Sampling And Composition (COSAC) experiment of the European Space Agency (ESA) Rosetta space mission to be launched in 2003 for a rendez-vous with comet 46 P/Wirtanen in 2011. The high efficiency and speed of analysis of this column at both atmospheric and vacuum outlet column pressure is demonstrated, and the kinetic mass transfer contribution of this carbon molecular sieve adsorbent is calculated. Besides, differential adsorption enthalpies of several gases and light hydrocarbons were determined from the variation of retention volume with temperature. The data indicate close adsorption behaviors on the Carbobond porous layer adsorbent and on the carbon molecular sieve Carboxen support used to prepare the packed columns. Moreover, taking into account the in situ operating conditions of the experiment, a study of 2 columns with different porous layer thickness allowed to optimize the separation of the target components and to select the column parameters compatible with the instrument constraints. Comparison with columns of similar selectivity shows that these capillary columns are the first ones able to perform the same work as the packed and micro-packed columns dedicated to the separation of this range of compounds in GC space exploration.

Szopa, C.; Sternberg, R.; Coscia, D.; Raulin, F.; Vidal-Madjar, C.

233

Stable carbon and nitrogen isotope analysis of avian uric acid.  

PubMed

We report results obtained using a new technique developed to measure the stable-isotope composition of uric acid isolated from bird excreta (guano). Results from a diet-switch feeding trial using zebra finches suggest that the delta(13)C of uric acid in the guano equilibrates with the diet of the bird within 3 days of a change in diet, while the equilibration time for delta(15)N may be longer. The average carbon isotope discrimination between uric acid and food before the diet switch was +0.34 +/- 1 per thousand (1sigma) while after the diet switch this increased slightly to +0.83 +/- 0.7 per thousand (1sigma). Nitrogen isotope discrimination was +1.3 +/- 0.3 per thousand (1sigma) and +0.3 +/- 0.3 per thousand (1sigma) before and after the diet switch; however, it is possible that the nitrogen isotope values did not fully equilibrate with diet switch over the course of the experiment. Analyses of other chemical fractions of the guano (organic residue after uric acid extraction and non-uric acid organics solubilised during extraction) suggest a total range of up to 3 per thousand for both delta(13)C and delta(15)N values in individual components of a single bulk guano sample. The analysis of natural samples from a range of terrestrial and marine species demonstrates that the technique yields isotopic compositions consistent with the known diets of the birds. The results from natural samples further demonstrate that multiple samples from the same species collected from the same location yield similar results, while different species from the same location exhibit a range of isotopic compositions indicative of different dietary preferences. Given that many samples of guano can be rapidly collected without any requirement to capture specimens for invasive sampling, the stable-isotope analysis of uric acid offers a new, simple and potentially powerful tool for studying avian ecology and metabolism. PMID:18837063

Bird, Michael I; Tait, Elaine; Wurster, Christopher M; Furness, Robert W

2008-11-01

234

Synthesis and application of carbonated fatty acid esters from carbon dioxide including a life cycle analysis.  

PubMed

Carbon dioxide can be used in various ways as a cheap C1 source. However, the utilization of CO2 requires energy or energy-rich reagents, which leads to further emissions, and therefore, diminishes the CO2-saving potential. Therefore, life cycle assessment (LCA) is required for each process that uses CO2 to provide valid data for CO2 savings. Carbon dioxide can be incorporated into epoxidized fatty acid esters to provide the corresponding carbonates. A robust catalytic process was developed based on simple halide salts in combination with a phase-transfer catalyst. The CO2-saving potential was determined by comparing the carbonates as a plasticizer with an established phthalate-based plasticizer. Although CO2 savings of up to 80 % were achieved, most of the savings arose from indirect effects and not from CO2 utilization. Furthermore, other categories have been analyzed in the LCA. The use of biobased material has a variety of impacts on categories such as eutrophication and marine toxicity. Therefore, the benefits of biobased materials have to be evaluated carefully for each case. Finally, interesting properties as plasticizers were obtained with the carbonates. The volatility and water extraction could be improved relative to the epoxidized system. PMID:24616303

Schäffner, Benjamin; Blug, Matthias; Kruse, Daniela; Polyakov, Mykola; Köckritz, Angela; Martin, Andreas; Rajagopalan, Prasanna; Bentrup, Ursula; Brückner, Angelika; Jung, Sebastian; Agar, David; Rüngeler, Bettina; Pfennig, Andreas; Müller, Karsten; Arlt, Wolfgang; Woldt, Benjamin; Grass, Michael; Buchholz, Stefan

2014-04-01

235

The inhibition of low carbon steel corrosion in hydrochloric acid solutions by succinic acid  

Microsoft Academic Search

The effect of succinic acid (SA) on the corrosion inhibition of a low carbon steel (LCS) electrode has been investigated in aerated non-stirred 1.0M HCl solutions in the pH range (2–8) at 25°C. Weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behaviour in the absence and presence of different concentrations of

Mohammed A. Amin; Sayed S. Abd El-Rehim; E. E. F. El-Sherbini; Rady S. Bayoumi

2007-01-01

236

Carbon emissions from a temperate peat fire and its relevance to interannual variability of trace atmospheric greenhouse gases  

NASA Astrophysics Data System (ADS)

The contribution of wildfire in peatlands outside of boreal and tropical regions to interannual variability of global carbon emissions has been relatively little studied. There are 0.19 to 0.88 million km2 of localized peat deposits in the temperate zone (30-50° latitude) where drainage and climate change may affect the status of this potentially large carbon pool. For example, in the coastal plain of North Carolina, USA, where wildfire is common, over 325 teragrams of carbon (Tg C) are stored in peat deposits up to 5 m deep. We estimated carbon emissions for a temperate peatland fire in North Carolina using remote sensing to reconstruct burn severity and topographic lidar to constrain peat burn depths. Total carbon emissions for the fire ranged from 1 to 3.8 Tg, with spatially heterogeneous patterns of carbon fluxes (0.2 to 11 kg C m-2) responding to variation in vegetation type, peat burn depth, soil substrate (mineral or organic), and fire severity. To maintain a carbon sink in this region at the current rates of carbon sequestration (0.109 to 0.127 kg C m-2 yr-1) we estimated a fire return interval of greater than 20-80 years. Continued drainage and future drought could decrease the fire return interval to less than 20 years or increase peat burn depths thereby converting these peatlands into a net carbon source. On a global scale, this study suggests that temperate peatland fires may emit up to 0.32 petagrams of carbon during drought years, a significant contribution to interannual greenhouse gas variability.

Poulter, Benjamin; Christensen, Norman L.; Halpin, Patrick N.

2006-03-01

237

Separation of gases through gas enrichment membrane composites  

DOEpatents

Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

Swedo, R.J.; Kurek, P.R.

1988-07-19

238

Separation of gases through gas enrichment membrane composites  

DOEpatents

Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

Swedo, Raymond J. (Mt. Prospect, IL) [Mt. Prospect, IL; Kurek, Paul R. (Schaumburg, IL) [Schaumburg, IL

1988-01-01

239

Lithium insertion into the composites of acid-oxidized carbon nanotubes and tin oxide  

Microsoft Academic Search

Lithium intercalation into the composites of acid-oxidized carbon nanotubes and tin oxide was studied in an electrolyte system, 1 M solution of LiPF6 dissolved in a 50:50 mixture by volume of ethylene carbonate (EC) and dimethyl carbonate (DMC). The electrochemical method that is constant current charge–discharge test was used for electrochemical properties of the acid-oxidized carbon nanotubes and tin oxide. The

Zhanhong Yang; Qingwei Wang; Jianli Wang; Zaifeng Li; Shangbin Sang

2007-01-01

240

Influence of Acid Modification on Selective Phenol Hydrogenation Over Pd\\/Activated Carbon Catalysts  

Microsoft Academic Search

The influence of the acid treatment on cyclohexanone selectivity of phenol hydrogenation over Pd on active carbon was studied\\u000a in liquid phase reaction and by temperature-programmed desorption. Acid treatment of activated carbon led to an increased\\u000a cyclohexanone\\/cyclohexanol ratio. Acid modification of the carbon support enriched the electron density of Pd, and enhanced\\u000a the desorption of the phenoxy species, which resulted

Shingo Watanabe; Venu Arunajatesan

2010-01-01

241

Carbon Dioxide Information Analysis Center and World Data Center - A for atmospheric trace gases. Fiscal year 1996, annual report  

SciTech Connect

Fiscal year 1996 was especially productive for the Carbon Dioxide Information Analysis Center (CDIAC) at Oak Ridge National Laboratory (ORNL). This report describes publications and statistical data from the CDIAC.

Cushman, R.M.; Boden, T.A.; Jones, S.B. [and others

1997-02-01

242

Amino acids of the Murchison meteorite. I - Six carbon acyclic primary alpha-amino alkanoic acids  

NASA Technical Reports Server (NTRS)

Six of the seven chain isomers of six-carbon acyclic primary alpha-amino alkanoic acids (leucine isomers) have been either identified or confirmed in hot-water extracts of the Murchison meteorite using combined gas chromatography-mass spectrometry (GC-MS) and ion exchange chromatography. 2-Amino-2-ethylbutyric acid, 2-amino-2,3-dimethylbutyric acid, pseudoleucine, and 2-methylnorvaline were positively identified by GC-MS. These amino acids have not been previously reported to occur in natural materials and may be uniquely meteoritic in origin. The presence of leucine and isoleucine (including the diastereoisomer, alloisoleucine) was confirmed. Peaks corresponding to norleucine were seen by ion-exchange and gas chromatography but characteristic mass spectra were not obtained. The alpha-branched chain isomers in this series are quantitatively the most significant. These results are compared with literature data on amino acid synthesis by electrical discharge and Fischer-Tropsch-type catalysis. Neither model system produces an amino acid suite that is completely comparable to that found in the Murchison meteorite.

Cronin, J. R.; Gandy, W. E.; Pizzarello, S.

1981-01-01

243

Amino acids of the Murchison meteorite: I. Six carbon acyclic primary alpha-amino alkanoic acids.  

PubMed

Six of the seven chain isomers of six-carbon acyclic primary alpha-amino alkanoic acids (leucine isomers) have been either identified or confirmed in hot-water extracts of the Murchison meteorite using combined gas chromatography-mass spectrometry (GC-MS) and ion exchange chromatography. 2-Amino-2-ethylbutyric acid, 2-amino-2,3-dimethylbutyric acid, pseudoleucine, and 2-methylnorvaline were positively identified by GC-MS. These amino acids have not been previously reported to occur in natural materials and may be uniquely meteoritic in origin. The presence of leucine and isoleucine (including the diastereoisomer, alloisoleucine) was confirmed. Peaks corresponding to norleucine were seen by ion-exchange and gas chromatography but characteristic mass spectra were not obtained. The alpha-branched chain isomers in this series are quantitatively the most significant. These results are compared with literature data on amino acid synthesis by electrical discharge and Fischer-Tropsch-type catalysis. Neither model system produces an amino acids suite that is completely comparable to that found in the Murchison meteorite. PMID:7277509

Cronin, J R; Gandy, W E; Pizzarello, S

1981-01-01

244

Measurement of fossil fuel carbon dioxide and other anthropogenic trace gases from MEGAPOLI intensive campaign in Paris during winter 2010.  

NASA Astrophysics Data System (ADS)

The Paris agglomeration is the third biggest megacity in Europe (12 million inhabitants) and according to national emission inventories, is responsible for 15 % of the French anthropogenic CO2 emissions mainly originating from road transport, and residential and industrial energy consumption. The objective of our feasibility study was to design an efficient monitoring strategy in order to quantify future trends in anthropogenic CO2 emission in Paris area. During the winter campaign of the European project MEGAPOLI and the French project CO2-MEGAPARIS, we performed measurements of CO2 and related trace gases from January to February 2010. The RAMCES (Atmospheric Network for Greenhouse Gases Monitoring) team at LSCE monitored CO2 and CO mixing ratio with high temporal resolution using instruments based on Cavity Ring Down Spectroscopy (CRDS) in the thirteenth arrondissement of Paris (south). We also sampled air in more than fifty flasks covering three full days at the same place. Flask were analysed in the RAMCES central laboratory with a Gas Chromatograph system for CO2, CO, CH4, N2O, SF6 and H2 mixing ratios and also by Mass Spectroscopy for CO2 isotopic ratios (?13C and ?18O). In order to quantify the fossil fuel CO2 (CO2ff) most flasks were analysed at INSTAAR for ?14C in CO2. In addition, 13CO2 isotopic ratio and total CO2 concentration were measured at high temporal resolution (< 1 min) over three days at Paris with the SIMCO instrument developed at LPMAA. In parallel with the Paris measurements, in-situ CO2, CO and other trace gases were monitored at Gif-sur-Yvette, a semi urban station 20km south west of Paris and also at the Trainou tower, 100 km south of Paris. Similar synoptic variations of CO2and CO mixing ratios were found in Paris and Gif with maximum mixing ratio up to 495 ppm CO2 and 1000 ppb CO downtown Paris. The mean diurnal variation during this winter period shows a peak to peak amplitude of 15 ppm CO2 and 150 ppb CO at Paris and 10 ppm CO2 and 40 CO ppb at Gif station. Using the MEGAPOLI database we will test different tracers (CO, VOCs, NOx) as possible candidate to quantify CO2ff (fossil fuel) based on calibration of these tracers against CO2ff estimates based on D14C. These results from the campaign will be compared to the emission inventories from EDGAR 4.2 (global inventories) and the national ones from CITEPA and AirParif.

Lopez, M.; Schmidt, M.; Delmotte, M.; Gros, V.; Mondelain, D.; Lehman, S. J.; Ramonet, M.; Vuillemin, C.; Xueref-Remy, I.

2012-04-01

245

Measurement of fossil fuel carbon dioxide and other anthropogenic trace gases from MEGAPOLI intensive campaign in Paris during winter 2010  

NASA Astrophysics Data System (ADS)

The Paris agglomeration is the third biggest megacity in Europe (12 million inhabitants) and according to national emission inventories, is responsible for 15 % of the French anthropogenic CO2 emissions mainly originating from road transport, residential and industrial energy consumption. The objective of our feasibility study was to design an efficient monitoring strategy in order to quantify future trends in anthropogenic CO2 emission in Paris area. During the winter campaign of the European project MEGAPOLI and French project CO2-MEGAPARIS, we performed measurements of CO2 and related trace gases from January to February 2010. The RAMCES (Atmospheric Network for Greenhouse Gases Monitoring) team at LSCE monitored CO2 and CO mixing ratio with high temporal resolution using instruments based on Cavity Ring Down Spectroscopy (CRDS) in the thirteenth arrondissement of Paris (south). We also sampled air in more than fifty flasks covering three full days at the same place. Flasks were analysed in the RAMCES central laboratory with a Gas Chromatograph system for CO2, CO, CH4, N2O, SF6 and H2 mixing ratios and also by Mass Spectroscopy for CO2 isotopic ratios (?13C and ?18O). In order to quantify the fossil fuel CO2 (CO2ff) most flasks were analysed at INSTAAR for ?14C in CO2. In addition, 13CO2 isotopic ratio and total CO2 concentration were measured at high temporal resolution (< 1 min) over three days at Paris with Tunable Diode Laser Spectroscope developed at LPMAA. In parallel with the Paris measurements, in-situ CO2, CO and other trace gases were monitored at Gif-sur-Yvette, a semi urban station 20km south west of Paris. Similar synoptic variations of CO2 and CO mixing ratios were found in Paris and Gif with maximum mixing ratio up to 495 ppm CO2 and 1000 ppb CO downtown Paris. The mean diurnal variation during this winter period shows peak to peak amplitude of 15 ppm CO2 and 150 ppb CO at Paris and 10 ppm CO2 and 40 CO ppb at Gif station. We focused on CO and NOx as tracer of fossil fuel emission to estimate CO2ff. We calibrated these tracers against CO2ff estimates based on ?14C. Moreover, ?13C measurements were used to quantify the contribution of the different combustion sources for CO2 emission. Finally, we compared our results to the emission inventories from EDGAR 4.2 (global inventories), IER (European inventory) and the national ones from CITEPA and AirParif.

Lopez, M.; Schmidt, M.; Delmotte, M.; Gros, V.; Mondelain, D.; Lehman, S.; Ramonet, M.; Vuillemin, C.; Xueref-remy, I. C.

2012-12-01

246

Water-soluble organic carbon, dicarboxylic acids, ketoacids, and ?-dicarbonyls in the tropical Indian aerosols  

Microsoft Academic Search

Tropical aerosol (PM10) samples (n = 49) collected from southeast coast of India were studied for water-soluble dicarboxylic acids (C2–C12), ketocarboxylic acids (C2–C9), and ?-dicarbonyls (glyoxal and methylglyoxal), together with analyses of total carbon (TC) and water-soluble organic carbon (WSOC). Their distributions were characterized by a predominance of oxalic acid followed by terephthalic (t-Ph), malonic, and succinic acids. Total concentrations

Chandra Mouli Pavuluri; Kimitaka Kawamura; T. Swaminathan

2010-01-01

247

Atmospheric gases  

NSDL National Science Digital Library

Which gases make up the atmosphere? This activity page, part of an interactive laboratory series for grades 8-12, introduces students to the gaseous components of the atmosphere. Students explore the main gases of the atmosphere using a pop-up pie chart. Descriptions of the gases and their percentages in the atmosphere are provided. Students read about water vapor in the atmosphere, and an animation shows a simplified process of precipitation. A pop-up window explains the effects of dust on the atmosphere, and a photograph shows how large amounts of dust in the atmosphere create the reds and oranges displayed in sunsets. Finally, ozone is introduced to students as a necessary component of human life on Earth. Copyright 2005 Eisenhower National Clearinghouse

University of Utah. Astrophysics Science Project Integrating Research and Education (ASPIRE)

2003-01-01

248

Visible-light photoconversion of carbon dioxide into organic acids in an aqueous solution of carbon dots.  

PubMed

Carbon "quantum" dots (or carbon dots) have emerged as a new class of optical nanomaterials. Beyond the widely reported bright fluorescence emissions in carbon dots, their excellent photoinduced redox properties that resemble those found in conventional semiconductor nanostructures are equally valuable, with photon-electron conversion applications from photovoltaics to CO2 photocatalytic reduction. In this work we used gold-doped carbon dots from controlled synthesis as water-soluble catalysts for a closer examination of the visible-light photoconversion of CO2 into small organic acids, including acetic acid (for which the reduction requires many more electrons than that for formic acid) and, more interestingly, for the significantly enhanced photoconversion with higher CO2 pressures over an aqueous solution of the photocatalysts. The results demonstrate the nanoscale semiconductor-equivalent nature of carbon dots, with excellent potential in energy conversion applications. PMID:24972094

Sahu, Sushant; Liu, Yamin; Wang, Ping; Bunker, Christopher E; Fernando, K A Shiral; Lewis, William K; Guliants, Elena A; Yang, Fan; Wang, Jinping; Sun, Ya-Ping

2014-07-22

249

Functionalization of single-walled carbon nanotubes with ribonucleic acids  

NASA Astrophysics Data System (ADS)

The optical properties of single-walled carbon nanotubes (SWCNTs) dispersed in aqueous solutions of ribonucleic acids (RNA) purified from Escherichia coli were studied using photoluminescence (PL), Raman, and absorption spectroscopy. SWCNT-RNA complexes, down to a single isolated nanotube level, were successfully synthesized. SWCNT signatures in Raman, PL, and absorption spectroscopy were observed from the SWCNT-RNA complexes. Observation of two distinct PL peaks, one at 1.248 eV and the other at 1.392 eV, confirmed the existence of isolated (6,5) and (6,4) SWCNTs, respectively. Atomic force microscope images and height profiles also showed evidence of isolated SWCNT-RNA complex.

Park, June; Kim, Sejin; Seong, Maeng-Je; Kim, Yu Jin; Go, Hayoung; Lee, Kangseok

2013-12-01

250

Deintercalation of carbonate ions from carbonate-type layered double hydroxides (LDHs) using acid–alcohol mixed solutions  

Microsoft Academic Search

Because of the high affinity of carbonate ions (CO32?) for LDHs (layered double hydroxides), their decarbonation—deintercalation of carbonate ions and conversion into LDHs containing other anions—has been considered difficult. So far, dilute acids have been used for decarbonation with additional salt to enhance the reaction. We found that the acid resistance of the LDHs is much higher in alcohols such

Nobuo Iyi; Hirohisa Yamada; Takayoshi Sasaki

2011-01-01

251

USE OF STABLE CARBON ISOTOPE RATIOS OF FATTY ACIDS TO EVALUATE MICROBIAL CARBON SOURCES IN TERRESTRIAL ENVIRONMENTS  

EPA Science Inventory

We use measurements of the concentration and stable carbon isotopic ratio (D 13C) of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels and microbial carbon source. We found that intensive sugar cane cultivation leads to ...

252

USE OF THE COMPOSITION AND STABLE CARBON ISOTOPE RATIO OF MICROBIAL FATTY ACIDS TO STUDY CARBON CYCLING  

EPA Science Inventory

We use measurements of the concentration and stable carbon isotopic ratio (Gamma 13C) of individual microbial phospholipid fatty acids (PLFAS) in soils and sediments as indicators of live microbial biomass levels and microbial carbon source. For studies of soil organic matter (SO...

253

Enhancement of electrochemiluminesence of lucigenin by ascorbic acid at single-wall carbon nanotube film-modified glassy carbon electrode  

Microsoft Academic Search

The electrochemiluminescent behavior of lucigenin on a single-wall carbon nanotube\\/DMF film-modified glassy carbon electrode was studied in this paper. Comparing with the bare glassy carbon electrode, the electrochemiluminescent of lucigenin at modified electrode is more stable and without tedious procedure for clean-up the surface of modified electrode. It has been found that ascorbic acid could enhance the electrochemiluminescent intensity of

Jinhua Chen; Zhenyu Lin; Guonan Chen

2007-01-01

254

A tabulation of meterorological variables and concentrations of helium, carbon dioxide, oxygen, and nitrogen in soil gases collected regularly from four sites at the Roosevelt Hot Springs Known Geothermal Resources Area, Utah  

Microsoft Academic Search

A U.S. Geological Survey report is presented giving a tabulation of meterorological variables and concentrations of helium, carbon dioxide, oxygen, and nitrogen in soil gases collected regularly from four sites at the Roosevelt Hot Springs Known Geothermal Resources Area, Utah.

Hinkle

1989-01-01

255

Carbon Dioxide Information Analysis Center and World Data Center-A for atmospheric trace gases: Fiscal year 1995 annual report  

SciTech Connect

Fiscal year 1995 was both a very productive year for the Carbon Dioxide Information Analysis Center and a year of significant change. This document presents information about the most notable accomplishments made during the year. Topics include: high-lights; statistics; future plans; publications, presentations, and awards; and change in organization and staff.

Burtis, M.D. [comp.; Cushman, R.M.; Boden, T.A.; Jones, S.B.; Nelson, T.; Stoss, F.W.

1996-01-01

256

The interesterification of edible palm oil by stearic acid in supercritical carbon dioxide  

Microsoft Academic Search

A continuous flow apparatus is set up to study the enzymatic interesterification of palm oil by stearic acid in supercritical carbon dioxide. Domestic edible palm oil is mixed with stearic acid and loaded to a saturation tank in which the oil is extracted by supercritical carbon dioxide. The current of the extraction solution bubbled from the saturation tank is delivered

Ming-Tsai Liang; Chun-Hao Chen; Roo-Chain Liang

1998-01-01

257

Adsorption of lignite-derived humic acids on coal-based mesoporous activated carbons  

Microsoft Academic Search

The adsorption by a coal-based mesoporous activated carbon of humic acids (HAs) isolated from two Polish lignites was studied. For comparison, a commercial Aldrich humic acid was also included into this study. The differences in chemical structure and functional groups of HAs were determined by elemental analysis and infrared spectroscopy DRIFT. Two activated carbons used differed in terms of mesopore

Ewa Lorenc-Grabowska; Gra?yna Gryglewicz

2005-01-01

258

Sorption of boric acid and borax by activated carbon impregnated with various compounds  

Microsoft Academic Search

The separation of boron compounds, boric acid and borax from aqueous solution by activated carbon before and after impregnation with various compounds was studied. A series of activated carbons was prepared from coconut shell impregnated with calcium and barium chlorides, citric and tartaric acids. The examined processes were performed in batch and continuous systems under equilibrium and dynamic conditions. Impregnation

Lj. V. Rajakovi?; M. Dj. Risti?

1996-01-01

259

Hydrogen Generation During the Corrosion of Carbon Steel in Oxalic Acid.  

National Technical Information Service (NTIS)

This document summarizes a literature review that was performed to gain a more complete understanding of the hydrogen evolution reaction that occurs during the corrosion of carbon steel in oxalic acid. The theory of carbon steel corrosion in oxalic acid w...

B. J. Wiersma

2004-01-01

260

Surface modification of a granular activated carbon by citric acid for enhancement of copper adsorption  

Microsoft Academic Search

In this study, citric acid was used to modify a commercially available activated carbon to improve copper ion adsorption from aqueous solutions. The carbon was modified with 1.0 M citric acid, followed by an optional step of reaction with 1.0 M sodium hydroxide. It was found that the surface modification reduced the specific surface area by 34% and point of

J. Paul Chen; Shunnian Wu; Kai-Hau Chong

2003-01-01

261

Hydrogen-bond acidic functionalized carbon nanotubes (CNTs) with covalently-bound hexafluoroisopropanol groups  

Microsoft Academic Search

Hydrogen-bond acidic fluoroalcohol groups are directly attached to the backbone of single walled carbon nanotubes (SWCNTs) via carbon–carbon bonds without the introduction of intermediate heteroatoms. Hexafluoroisopropanol functional groups are exceptionally strong hydrogen-bond acids, and are added to the nanotube surface (via the substituted benzene para position) as 2-phenyl-1,1,1,3,3,3-hexafluoro-2-propanol (i.e., –(p-C6H4)C(CF3)2OH) using the aryl diazonium approach to create hydrogen-bond acidic carbon

Leonard S. Fifield; Jay W. Grate

2010-01-01

262

Mechanistic insight into the formation of acetic acid from the direct conversion of methane and carbon dioxide on zinc-modified H-ZSM-5 zeolite.  

PubMed

Methane and carbon dioxide are known greenhouse gases, and the conversion of these two C1-building blocks into useful fuels and chemicals is a subject of great importance. By solid-state NMR spectroscopy, we found that methane and carbon dioxide can be co-converted on a zinc-modified H-ZSM-5 zeolite (denoted as Zn/H-ZSM-5) to form acetic acid at a low temperature range of 523-773 K. Solid-state (13)C and (1)H MAS NMR investigation indicates that the unique nature of the bifunctional Zn/H-ZSM-5 catalyst is responsible for this highly selective transformation. The zinc sites efficiently activate CH4 to form zinc methyl species (-Zn-CH3), the Zn-C bond of which is further subject to the CO2 insertion to produce surface acetate species (-Zn-OOCCH3). Moreover, the Brønsted acid sites play an important role for the final formation of acetic acid by the proton transfer to the surface acetate species. The results disclosed herein may offer the new possibility for the efficient activation and selective transformation of methane at low temperatures through the co-conversion strategy. Also, the mechanistic understanding of this process will help to the rational design of robust catalytic systems for the practical conversion of greenhouse gases into useful chemicals. PMID:23981101

Wu, Jian-Feng; Yu, Si-Min; Wang, Wei David; Fan, Yan-Xin; Bai, Shi; Zhang, Chuan-Wei; Gao, Qiang; Huang, Jun; Wang, Wei

2013-09-11

263

Isotopic composition of gases from mud volcanoes  

SciTech Connect

A study has been made of the isotopic composition of the carbon in methane and carbon dioxide, as well as hydrogen in the methane, in the gases of mud volcanoes, for all main mud volcano areas in the USSR. The isotopic composition of carbon and hydrogen in methane shows that the gases resemble those of oil and gas deposits, while carbon dioxide of these volcanoes has a heavier isotopic composition with a greater presence of ''ultraheavy'' carbon dioxide. By the chemical and isotopic composition of gases, Azerbaidzhan and South Sakhalin types of mud volcano gases have been identified, as well as Bulganak subtypes and Akhtala and Kobystan varieties. Correlations are seen between the isotopic composition of gases and the geological build of mud volcano areas.

Valysaev, B.M.; Erokhin, V.E.; Grinchenko, Y.I.; Prokhorov, V.S.; Titkov, G.A.

1985-09-01

264

Acrylic acid-diphenylamine sulphonic acid copolymer threshold inhibitor for sulphate and carbonate scales in cooling water systems  

Microsoft Academic Search

Formation of mineral scales of carbonate and sulphate poses significant problems in cooling water systems. For the control of calcium carbonate and calcium sulphate scales, copolymer of acrylic acid-diphenyl amine sulphonic acid (AA-DPSA) was tried as the anticalant in the respective brines. The copolymer of AA-DPSA was synthesized by following a free radical polymerization procedure. AA-DPSA was characterized by Fourier

P. Shakkthivel; T. Vasudevan

2006-01-01

265

Anaerobic mineralization of quaternary carbon atoms: isolation of denitrifying bacteria on pivalic acid (2,2-dimethylpropionic acid).  

PubMed

The degradability of pivalic acid was established by the isolation of several facultative denitrifying strains belonging to Zoogloea resiniphila, to Thauera and Herbaspirillum, and to Comamonadaceae, related to [Aquaspirillum] and Acidovorax, and of a nitrate-reducing bacterium affiliated with Moraxella osloensis. Pivalic acid was completely mineralized to carbon dioxide. The catabolic pathways may involve an oxidation to dimethylmalonate or a carbon skeleton rearrangement, a putative 2,2-dimethylpropionyl coenzyme A mutase. PMID:12620885

Probian, Christina; Wülfing, Annika; Harder, Jens

2003-03-01

266

Effect of carbon material on Pd catalyst for formic acid electrooxidation reaction  

NASA Astrophysics Data System (ADS)

Effect of several usually used carbon materials on Pd catalyst for formic acid electrooxidation reaction is studied by physical characterization and electrochemical measurements. New active sites are formed due to the Pd and carbon interaction which is confirmed by the XPS measurements, and electrochemical impedance spectroscopy confirms that the presence of the carbon material reduced the charge transfer resistance. Further, an improved fuel cell performance is observed when integrating the carbon-modified Pd catalyst in to a direct formic acid fuel cell. The results reveal that the carbon material is not only used as support, but also involves the new active sites formation.

Chang, Jinfa; Li, Songtao; Feng, Ligang; Qin, Xiujuan; Shao, Guangjie

2014-11-01

267

Abundances of Cloud-Related Gases in the Venus Atmosphere as Inferred from Observed Radio Opacity  

Microsoft Academic Search

Various radio-analytical techniques have detected microwave opacity in the middle atmosphere of Venus, well above the main carbon dioxide opacity of the lower atmosphere. Consideration of the amount, distribution, and effects of the constituents which produce the main cloud layer at about 50 km altitude, indicate that such cloud-related gases, especially sulfuric acid vapor, are the predominant source of the

Paul Gregory Steffes

1982-01-01

268

Teacher's Resource Book for Balloons and Gases. Grade 6. Revised. Anchorage School District Elementary Science Program.  

ERIC Educational Resources Information Center

This resource book introduces sixth-grade children to the physical and chemical properties of gases. The unit begins with an investigation of acids and bases. Students then generate carbon dioxide, oxygen, and hydrogen, and investigate the properties of each. The unit culminates with an activity involving an unknown gas. Students conduct tests to…

Anchorage School District, AK.

269

Electron Paramagnetic Resonance (EPR) Investigation of Limestones and Their Calcines and Correlation with Reactivity with Acid Gases.  

National Technical Information Service (NTIS)

A research program was undertaken to investigate a selected set of calcined and uncalcined carbonate rock samples by electron paramagnetic resonance (EPR) spectroscopy in order to assist in the characterization of marls and chalks to identify properties w...

N. A. Ashford F. H. Jarke

1972-01-01

270

Arundo donax cane as a precursor for activated carbons preparation by phosphoric acid activation  

Microsoft Academic Search

Canes from Arundo donax, a herbaceous rapid-growing plant, were used as precursor for activated carbon preparation by phosphoric acid activation under a self-generated atmosphere. The influence of the carbonization temperature in the range 400–550 °C and of the weight ratio phosphoric acid to precursor (R=1.5–2.5) on the developed porous structure of the resulting carbons was studied for 1 h of

T Vernersson; P. R Bonelli; E. G Cerrella; A. L Cukierman

2002-01-01

271

Distribution of dicarboxylic acids and carbon isotopic compositions in aerosols from 1997 Indonesian forest fires  

Microsoft Academic Search

Fine aerosol particles collected in Southeast Asia during 1997 Indonesian forest fires were studied for the concentrations of total carbon (TC), water-soluble organic carbon (WSOC) and low molecular weight dicarboxylic acids (C2-C12) as well as carbon isotopic ratios of TC (delta13CTC). TC and WSOC showed a large increase during the heavy forest fire event. At the same period, dicarboxylic acids,

M. Narukawa; K. Kawamura; N. Takeuchi; T. Nakajima

1999-01-01

272

"Electroless Deposition of bias(4 '-(4-bridal)-2 2 ': 6 ' 2 ''-terpyridine)iron(II) thousandth Complex onto Carbon Nanotubes Modified Glassy Carbon Electrode: Application to Simultaneous Determination of Ascorbic Acid Tupman and Eric Acid"  

EPA Pesticide Factsheets

Did you mean: "Electroless Deposition of bias(4 '-(4-bridal)-2 2 ': 6 ' 2 ''-terpyridine)iron(II) thousandth Complex onto Carbon Nanotubes Modified Glassy Carbon Electrode: Application to Simultaneous Determination of Ascorbic Acid Tupman and Eric Acid" ?

273

Carbon nanotube supported Pt–Ni catalysts for preferential oxidation of CO in hydrogen-rich gases  

Microsoft Academic Search

A series of carbon nano-tubes supported platinum-nickel catalysts were prepared and used for CO preferential oxidation in H2-rich streams. The catalysts were characterized by using N2-adsorption, XRD, HRTEM, H2-TPD and H2-TPR techniques. Effects of platinum and nickel loading amount, CO2 and H2O in the feed stream on the activity and selectivity over the catalysts were investigated. The results of catalytic

Suhong Lu; Cheng Zhang; Yuan Liu

2011-01-01

274

Carbon Dioxide Analysis Center and World Data Center-A for Atmospheric Trace Gases fiscal year 1997 annual report  

SciTech Connect

Fiscal year (FY) 1997 was another exciting and productive one for the Carbon Dioxide Information Analysis Center (CDIAC) at the Oak Ridge National Laboratory. During FY 1997, CDIAC launched the Quality Systems Science Center for the North American Research Strategy for Tropospheric Ozone (NARSTO). The purpose of NARSTO--a US-Canada-Mexico initiative of government agencies, industry, and the academic research community--is to improve the understanding of the formation and transport of tropospheric ozone.

Burtis, M.D. [comp.; Cushman, R.M.; Boden, T.A.; Jones, S.B.; Kaiser, D.P.; Nelson, T.R.

1998-03-01

275

Studies of the terrestrial O{sub 2} and carbon cycles in sand dune gases and in biosphere 2  

SciTech Connect

Molecular oxygen in the atmosphere is coupled tightly to the terrestrial carbon cycle by the processes of photosynthesis, respiration, and burning. This dissertation examines different aspects of this coupling in four chapters. Chapter 1 explores the feasibility of using air from sand dunes to reconstruct atmospheric O{sub 2} composition centuries ago. Such a record would reveal changes in the mass of the terrestrial biosphere, after correction for known fossil fuel combustion, and constrain the fate of anthropogenic CO{sub 2}.

Severinghaus, J.P.

1995-12-31

276

Modelling of microbial carbon and nitrogen turnover in soil with special emphasis on N-trace gases emission  

Microsoft Academic Search

We present a new model unifying state-of-the-art descriptions of microbial processes for denitrification, nitrification and\\u000a decomposition of soil organic matter. The model is of medium complexity, filling a gap between simplistic model approaches\\u000a with low predictive power and complex models, which are difficult to verify experimentally. The model Microbial Carbon and Nitrogen Turnover in soils (MiCNiT) is written in Ansi

Sergey Blagodatsky; Rüdiger Grote; Ralf Kiese; Christian Werner; Klaus Butterbach-Bahl

277

Acid-base characteristics of organic carbon in the HUMEX Lake Skjervatjern  

SciTech Connect

The Humic Lake Acidification Experiment (HUMEX) was launched in 1988 to study the role of humic substances in the acidification of surface waters and the impacts of acidic deposition on the chemical and biological properties of humic substances. This subproject was designed to determine the contribution of organic acids to the acidity of Lake Skjervatjern (the HUMEX Lake) and the impacts of the acidification on the characteristics of organic carbon. In order to get an empirical measure for organic acidity, dissolved organic carbon (DOC) was fractionated, isolated, and base-titrated from each half of Lake Skjervatjern. Hydrophobic acids were the dominant organic carbon fraction; the total organic acid content was generally greater than 80% of the DOC. The reliability of the fractionation procedure was tested with synthetic acids and the Nordic Fulvic acid. The DOC fractions did not show high variation over the 1.5-y acidification period. Hydrophilic acids had consistently greater exchange acidities compared to hydrophobic acids, averaging 12.9 [mu]eq/mg DOC vs. 10.9 [mu]eq/mg DOC, respectively. The dissociation of organic acids during acid-base titrations clearly increased with increasing pH. The high organic anion contribution to the ion balances indicates that humic matter is an important acidity source in Lake Skjervatjern. There are slight signs that the contribution of organic acids to overall lake acidity has decreased since acidification was initiated. 22 refs., 5 figs., 1 tab.

Kortelainen, P.; David, M.B.; Roila, T.; Maekinen, I. (National Board of Waters and the Environment, Helsinki (Finland))

1992-01-01

278

Reevaluation of the NOAA/CMDL carbon monoxide reference scale and comparisons with CO reference gases at NASA-Langley and the Fraunhofer Institut  

SciTech Connect

The carbon monoxide (CO) reference scale created by the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory (NOAA/CMDL) is used to quantify measurements of CO in the atmosphere, calibrate standards of other laboratories and to otherwise provide reference gases to the community measuring atmospheric CO. This reference scale was created based upon a set of primary standards prepared by gravimetric methods at CMDL and has been propagated to a set of working standards. In this paper we compare CO mixing ratios assigned to the working standards by three approaches: (1) calibration against the original gravimetric standards, (2) calibration using only working standards as the reference gas, and (3) calibration against three new gravimetric standards prepared to CMDL. The agreement between these values was typically better than 1%. The calibration histories of CMDL working standards are reviewed with respect to expected rates of CO change in the atmosphere. Using a Monte Carlo approach to simulate the effect of drifting standards on calculated mixing ratios, we conclude that the error solely associated with the maintenance of standards will limit the ability to detect small CO changes in the atmosphere. We also report results of intercalibration experiments conducted between CMDL and the Diode Laser Sensor Group (DACOM) at the NASA Langley Research Center (Hampton, Virginia), and CMDL and the Fraunhofer-Institut (Garmisch-Partenkirchen, Germany). Each laboratory calibrated several working standards for CO using their reference gases, and these results were compared to calibrations conducted by CMDL. The intercomparison of eight standards (CO concentrations between approximately 100 and approximately 165 ppb) by CMDL and NASA agreed to better than +/- 2%. (Abstract Truncated)

Novelli, P.C.; Collins, J.E. Jr.; Myers, R.C.; Sachse, G.W.; Scheel, H.E. [Univ. of Colordo, Boulder, CO (United States)] [Univ. of Colordo, Boulder, CO (United States); [Science and Technology Corporation, Hampton, VA (United States); [NOAA, Boulder, CO (United States); [NASA, Langley Research Center, Hampton, VA (United States); [Fraunhofer-Inst. fuer Atmospharishce Umweltforschung (Germany)

1994-06-01

279

Reevaluation of the NOAA/CMDL carbon monoxide reference scale and comparisons with CO reference gases at NASA-Langley and the Fraunhofer Institut  

NASA Technical Reports Server (NTRS)

The carbon monoxide (CO) reference scale created by the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory (NOAA/CMDL) is used to quantify measurements of CO in the atmosphere, calibrate standards of other laboratories and to otherwise provide reference gases to the community measuring atmospheric CO. This reference scale was created based upon a set of primary standards prepared by gravimetric methods at CMDL and has been propagated to a set of working standards. In this paper we compare CO mixing ratios assigned to the working standards by three approaches: (1) calibration against the original gravimetric standards, (2) calibration using only working standards as the reference gas, and (3) calibration against three new gravimetric standards prepared to CMDL. The agreement between these values was typically better than 1%. The calibration histories of CMDL working standards are reviewed with respect to expected rates of CO change in the atmosphere. Using a Monte Carlo approach to simulate the effect of drifting standards on calculated mixing ratios, we conclude that the error solely associated with the maintenance of standards will limit the ability to detect small CO changes in the atmosphere. We also report results of intercalibration experiments conducted between CMDL and the Diode Laser Sensor Group (DACOM) at the NASA Langley Research Center (Hampton, Virginia), and CMDL and the Fraunhofer-Institut (Garmisch-Partenkirchen, Germany). Each laboratory calibrated several working standards for CO using their reference gases, and these results were compared to calibrations conducted by CMDL. The intercomparison of eight standards (CO concentrations between approximately 100 and approximately 165 ppb) by CMDL and NASA agreed to better than +/- 2%. The calibration of six standards (CO concentrations between approximately 50 and approximately 210 ppb) by CMDL and the Fraunhofer-Institut agreed to within +/- 2% for four standards, and to within +/- 5% for all six standards.

Novelli, P. C.; Collins, J. E., Jr.; Myers, R. C.; Sachse, G. W.; Scheel, H. E.

1994-01-01

280

Greenhouse Gases  

NSDL National Science Digital Library

This is a lesson where learners engage in a radiating heat activity and an activity that measures temperature in models with and without greenhouse gases. Learners will draw conclusions about the effect of greenhouse gases on temperature and on human life and kinesthetically model the absorbing and re-radiation of heat. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes, prerequisite concepts, common misconceptions, student journal and reading. This is lesson 3 in the Astro-Venture Atmospheric Science Training Unit. The purpose of the unit is to increase studentsâ awareness of and interest in astrobiology and the many career opportunities that utilize science, math and technology skills. The lessons are designed for educators to use in conjunction with the Astro-Venture multimedia modules.

281

Novel graphene flowers modified carbon fibers for simultaneous determination of ascorbic acid, dopamine and uric acid.  

PubMed

A novel and sensitive carbon fiber electrode (CFE) modified by graphene flowers was prepared and used to simultaneously determine ascorbic acid (AA), dopamine (DA) and uric acid (UA). SEM images showed that beautiful and layer-petal graphene flowers homogeneously bloomed on the surface of CFE. Moreover, sharp and obvious oxidation peaks were found at the obtained electrode when compared with CFE and glassy carbon electrode (GCE) for the oxidation of AA, DA and UA. Also, the linear calibration plots for AA, DA and UA were observed, respectively, in the ranges of 45.4-1489.23 ?M, 0.7-45.21 ?M and 3.78-183.87 ?M in the individual detection of each component. By simultaneously changing the concentrations of AA, DA and UA, their oxidation peaks appeared at -0.05 V, 0.16 V and 2.6 V, and the good linear responses ranges were 73.52-2305.53 ?M, 1.36-125.69 ?M and 3.98-371.49 ?M, respectively. In addition, the obtained electrode showed satisfactory results when applied to the determination of AA, DA and UA in urine and serum samples. PMID:24140872

Du, Jiao; Yue, Ruirui; Ren, Fangfang; Yao, Zhangquan; Jiang, Fengxing; Yang, Ping; Du, Yukou

2014-03-15

282

Production of micro- and mesoporous carbons by pyrolysis of the lithium salts of aromatic acids  

Microsoft Academic Search

As a new process for the production of micro- and mesoporous carbon materials, the thermal decomposition of the lithium salts of aromatic acids (terephthalic acid, 1,3,5-benzenetricarboxylic acid, and 1,2,4,5-benzenetetracarboxylic acid) was followed by TGA, MS, SEM, TEM, elemental analysis, and N2 adsorption. The lithium salt of terephthalic acid was decomposed at temperatures above 550°C and then converted into a composite

Katsumi Kamegawa; Masaya Kodama; Keiko Nishikubo; Hiroshi Yamada; Yoshio Adachi; Hisayoshi Yoshida

2005-01-01

283

Sequestering CO(2) by mineral carbonation: stability against acid rain exposure.  

PubMed

Mineral carbonation is a potentially attractive alternative to storage of compressed CO(2) in underground repositories, known as geosequestration. Processes for the conversion of basic ores, such as magnesium silicates, to carbonates have been proposed by various researchers, with storage of the carbonate as backfill in the original mine representing a solid carbon sink. The stability of such carbon sinks against acid rain and other sources of strong acids is examined here. It is acknowledged that in the presence of strong acid, carbonates will dissolve and release carbon dioxide. A sensitivity analysis covering annual average rainfall and pH that may be encountered in industrialized areas of the United States, China, Europe, and Australia was conducted to determine maximum CO(2) rerelease rates from mineral carbonation carbon sinks. This analysis is based on a worst-case premise that is equivalent to assuming infinitely rapid kinetics of dissolution of the carbonate. The analysis shows that under any likely conditions of pH and rainfall, leakage rates of stored CO(2) are negligible. This is illustrated in a hypothetical case study under Australian conditions. It is thus proposed that sequestration by mineral carbonation can be considered to be permanent on practical human time scales. Other possible sources of acid have also been considered. PMID:20199068

Allen, Daniel J; Brent, Geoff F

2010-04-01

284

Noble Gases  

NASA Astrophysics Data System (ADS)

The noble gases are the group of elements - helium, neon, argon, krypton, xenon - in the rightmost column of the periodic table of the elements, those which have "filled" outermost shells of electrons (two for helium, eight for the others). This configuration of electrons results in a neutral atom that has relatively low electron affinity and relatively high ionization energy. In consequence, in most natural circumstances these elements do not form chemical compounds, whence they are called "noble." Similarly, much more so than other elements in most circumstances, they partition strongly into a gas phase (as monatomic gas), so that they are called the "noble gases" (also, "inert gases"). (It should be noted, of course, that there is a sixth noble gas, radon, but all isotopes of radon are radioactive, with maximum half-life a few days, so that radon occurs in nature only because of recent production in the U-Th decay chains. The factors that govern the distribution of radon isotopes are thus quite different from those for the five gases cited. There are interesting stories about radon, but they are very different from those about the first five noble gases, and are thus outside the scope of this chapter.)In the nuclear fires in which the elements are forged, the creation and destruction of a given nuclear species depends on its nuclear properties, not on whether it will have a filled outermost shell when things cool off and nuclei begin to gather electrons. The numerology of nuclear physics is different from that of chemistry, so that in the cosmos at large there is nothing systematically special about the abundances of the noble gases as compared to other elements. We live in a very nonrepresentative part of the cosmos, however. As is discussed elsewhere in this volume, the outstanding generalization about the geo-/cosmochemistry of the terrestrial planets is that at some point thermodynamic conditions dictated phase separation of solids from gases, and that the Earth and the rest of the inner solar were made by collecting the solids, to the rather efficient exclusion of the gases. In this grand separation the noble gases, because they are noble, were partitioned strongly into the gas phase. The resultant generalization is that the noble gases are very scarce in the materials of the inner solar system, whence their common synonym "rare gases."This scarcity is probably the most important single feature to remember about noble-gas cosmochemistry. As illustration of the absolute quantities, for example, a meteorite that contains xenon at a concentration of order 10 -10 cm3STP g -1 (4×10-15 mol g-1) would be considered relatively rich in xenon. Yet this is only 0.6 ppt (part per trillion, fractional abundance 10-12) by mass. In most circumstances, an element would be considered efficiently excluded from some sample if its abundance, relative to cosmic proportions to some convenient reference element, were depleted by "several" orders of magnitude. But a noble gas would be considered to be present in quite high concentration if it were depleted by only four or five orders of magnitude (in the example above, 10-10 cm3STP g-1 of xenon corresponds to depletion by seven orders of magnitude), and one not uncommonly encounters noble-gas depletion of more than 10 orders of magnitude.The second most important feature to note about noble-gas cosmochemistry is that while a good deal of the attention given to noble gases really is about chemistry, traditionally a good deal of attention is also devoted to nuclear phenomena, much more so than for most other elements. This feature is a corollary of the first feature noted above, namely scarcity. A variety of nuclear transmutation processes - decay of natural radionuclides and energetic particle reactions - lead to the production of new nuclei that are often new elements. Most commonly, the quantity of new nuclei originating in nuclear transmutation is very small compared to the quantity already present in the sample in question,

Podosek, F. A.

2003-12-01

285

Anaerobic Mineralization of Quaternary Carbon Atoms: Isolation of Denitrifying Bacteria on Pivalic Acid (2,2-Dimethylpropionic Acid)  

Microsoft Academic Search

The degradability of pivalic acid was established by the isolation of several facultative denitrifying strains belonging to Zoogloea resiniphila ,t oThauera and Herbaspirillum, and to Comamonadaceae, related to (Aquaspi- rillum) and Acidovorax, and of a nitrate-reducing bacterium affiliated with Moraxella osloensis. Pivalic acid was completely mineralized to carbon dioxide. The catabolic pathways may involve an oxidation to dimethyl- malonate or

Christina Probian; Annika Wulfing; Jens Harder

2003-01-01

286

Influences of pyrolysis condition and acid treatment on properties of durian peel-based activated carbon.  

PubMed

Durian peel was used for the synthesis of activated carbon used for adsorption of Basic Green 4 dye. Activated carbon was synthesised under either nitrogen (N(2)) atmospheric or vacuum pyrolysis, followed by carbon dioxide (CO(2)) activation. The synthesised activated carbon then was treated with hydrochloric acid (HCl) solution. The results showed that activated carbon synthesised under vacuum pyrolysis exhibited better properties and adsorption capacities than that under nitrogen atmospheric pyrolysis. The HCl treatment improved properties and adsorption capacities of activated carbons. Pseudo-second-order kinetics well described the adsorption of Basic Green 4. PMID:19695874

Nuithitikul, Kamchai; Srikhun, Sarawut; Hirunpraditkoon, Samorn

2010-01-01

287

Oxidation and reduction rates for organic carbon in the Amazon mainstream tributary and floodplain, inferred from distributions of dissolved gases  

NASA Technical Reports Server (NTRS)

Concentrations of CO2, O2, CH4, and N2O in the Amazon River system reflect an oxidation-reduction sequence in combination with physical mixing between the floodplain and the mainstem. Concentrations of CO2 ranged from 150 microM in the Amazon mainstem to 200 to 300 microM in aerobic waters of the floodplain, and up to 1000 microM in oxygen-depleted environments. Apparent oxygen utilization (AOU) ranged from 80 to 250 microM. Methane was highly supersaturated, with concentrations ranging from 0.06 microM in the mainstem to 100 microM on the floodplain. Concentrations of N2O were slightly supersaturated in the mainstem, but were undersaturated on the floodplain. Fluxes calculated from these concentrations indicated decomposition of 1600 g C sq m y(-1) of organic carbon in Amazon floodplain waters. Analysis of relationships between CH4, O2, and CO2 concentrations indicated that approximately 50 percent of carbon mineralization on the floodplain is anaerobic, with 20 percent lost to the atmoshphere as CH4. The predominance of anaerobic metabolism leads to consumption of N2O on the flood plane. Elevated concentrations of CH4 in the mainstem probably reflect imput from the floodplain, while high levels of CO2 in the mainstem are derived from a combination of varzea drainage and in situ respiration.

Richey, Jeffrey E.; Devol, Allan H.; Wofsy, Steven C.; Victoria, Reynaldo; Riberio, Maria N. G.

1986-01-01

288

Solubility of gases and the temperature dependency of whole leaf affinities for carbon dioxide and oxygen: an alternative perspective.  

PubMed

An analysis of the kinetics of simultaneous photosynthesis and photorespiration at the end of a diffusion path is applied to observed net photosynthetic rate as a function of O(2) and CO(2) concentrations. The data of Ku and Edwards (Plant Physiol. 59: 991-999, 1977) from wheat (Triticum aestivum L.) are analyzed in detail. Ku and Edwards, using an analysis that ignored diffusion resistance between the intercellular air space and fixation site, the competitive effect of CO(2) on photorespiration, and the actual concentrations of gases at the fixation site, concluded that: (a) the affinity coefficient of the leaf for CO(2) was approximately 3.5 to 5 micromolar; (b) this affinity coefficient is independent of temperature between 25 and 35 C; (c) the effect of O(2) was independent of temperature over this range; and (d) competition between CO(2) and O(2) is responsible for the major share of CO(2) loss from photosynthesis due to photorespiration. They suggest that using gas concentrations calculated as equilibium values in the liquid phase is very important in reaching these conclusions. By applying a more complete analysis to their data which includes diffusion in the cell, it is concluded that: (a) the affinity coefficient of the leaf for CO(2) is 0.1 to 1.1 micromolar; (b) the temperature dependence of this affinity coefficient cannot be determined from existing data, but there is no evidence to refute independent temperature effect on the two functions of ribulose-1,5-bisphosphate carboxylase-oxygenase being important in the regulation of whole leaf net photosynthesis; and (c) the competitive interplay of CO(2) and O(2) at ribulose-1,5-bisphosphate carboxylase may under certain conditions lead to a stimulation of fixation by the Calvin cycle because of photorespiration. These conclusions are reached whether CO(2) and O(2) are expressed as dissolved concentrations or as gas concentrations in the intercellular air space. The relative merits of these two expressions of concentration are discussed. PMID:16660837

Tenhunen, J D; Weber, J A; Yocum, C S; Gates, D M

1979-05-01

289

The Effect of Calcium Carbonate on the Stability of Acid Treated Papers.  

National Technical Information Service (NTIS)

Exposure of kraft wood pulps to an acidic medium results in a destabilization of wood pulp. The degree of destabilization appears to depend on the concentration of acid the pulp is exposed to. The addition of calcium carbonate to acid destabilized pulp do...

E. L. Graminski E. J. Parks

1980-01-01

290

BIOMASS BURNING AND THE PRODUCTION OF GREENHOUSE GASES  

Microsoft Academic Search

Biomass burning is a source of greenhouse gases, carbon dioxide, methane, and nitrous oxide. In addition, biomass burning is a source of chemically active gases, including carbon monoxide, nonmethane hydrocarbons, and nitric oxide. These gases, along with methane, lead to the chemical production of tropospheric ozone (another greenhouse gas) as well as control the concentration of the hydroxyl radical, which

Joel S. Levine

291

Electron microscopy of carbonaceous matter in Allende acid residues  

NASA Technical Reports Server (NTRS)

On the basis of characteristic diffuse ring diffraction patterns, much of the carbonaceous matter in a large suite of Allende acid residues has been identified as a variety of turbostratic carbon. Crystallites of this phase contain randomly stacked sp(2) hybridized carbon layers and diffraction patterns resemble those from carbon black and glassy carbon. Carbynes are probably absent, and are certainly restricted to less than 0.5% of these acid residues. The work of Ott et al. (1981) provides a basis for the possibility that turbostratic carbon is a carrier of noble gases, but an additional component - amorphous carbon - may be necessary to explain the high release temperatures of noble gases as well as the glassy character of many of the carbonaceous particles. Carbynes are considered to be questionable as important carriers of noble gases in the Allende acid residues.

Lumpkin, G. R.

1982-01-01

292

Electron microscopy of carbonaceous matter in Allende acid residues  

NASA Astrophysics Data System (ADS)

On the basis of characteristic diffuse ring diffraction patterns, much of the carbonaceous matter in a large suite of Allende acid residues has been identified as a variety of turbostratic carbon. Crystallites of this phase contain randomly stacked sp(2) hybridized carbon layers and diffraction patterns resemble those from carbon black and glassy carbon. Carbynes are probably absent, and are certainly restricted to less than 0.5% of these acid residues. The work of Ott et al. (1981) provides a basis for the possibility that turbostratic carbon is a carrier of noble gases, but an additional component - amorphous carbon - may be necessary to explain the high release temperatures of noble gases as well as the glassy character of many of the carbonaceous particles. Carbynes are considered to be questionable as important carriers of noble gases in the Allende acid residues.

Lumpkin, G. R.

293

Dissociation constants for carbonic acid determined from field measurements  

NASA Astrophysics Data System (ADS)

A number of workers have recently shown that the thermodynamic constants for the dissociation of carbonic acid in seawater of Mehrbach et al. are more reliable than measurements made on artificial seawater. These studies have largely been confined to looking at the internal consistency of measurements of total alkalinity (TA), total inorganic carbon dioxide (TCO 2) and the fugacity of carbon dioxide ( fCO 2). In this paper, we have examined the field measurements of pH, fCO 2, TCO 2 and TA on surface and deep waters from the Atlantic, Indian, Southern and Pacific oceans to determine the p K1, p K2 and p K2-p K1. These calculations are possible due to the high precision and accuracy of the field measurements. The values of p K2 and p K2-p K1 over a wide range of temperatures (-1.6-38°C) are in good agreement (within ±0.005) with the results of Mehrbach et al. The measured values of p K1 at 4°C and 20°C are in reasonable agreement (within ±0.01) with all the constants determined in laboratory studies. These results indicate, as suggested by internal consistency tests, that the directly measured values of p K1+p K2 of Mehrbach et al. on real seawater are more reliable than the values determined for artificial seawater. It also indicates that the large differences of p K2-p K1 (0.05 at 20°C) in real and artificial seawater determined by different investigators are mainly due to differences in p K2. These differences may be related to the interactions of boric acid with the carbonate ion. The values of p K2-p K1 determined from the laboratory measurements of Lee et al. and Lueker et al. at low fCO 2 agree with the field-derived data to ±0.016 from 5°C to 25°C. The values of p K2-p K1 decrease as the fCO 2 or TCO 2 increases. This effect is largely related to changes in the p K2 as a function of fCO 2 or TCO 2. The values of fCO 2 calculated from an input of TA and TCO 2, which require reliable values of p K2-p K1, also vary with fCO 2. The field data at 20°C has been used to determine the effect of changes of TCO 2 on p K2 giving an empirical relationship: pK 2TCO2= pK 2-1.6×10 -4( TCO2-2050) which is valid at TCO 2>2050 ?mol kg -1. This assumes that the other dissociation constants such as KB for boric acid are not affected by changes in TCO 2. The slope is in reasonable agreement with the laboratory studies of Lee et al. and Lueker et al. (-1.2×10 -4 to -1.9×10 -4). This equation eliminates the dependence of the calculated fCO 2 on the level of fCO 2 or TCO 2 in ocean waters ( ?=29.7 ?atm in fCO 2). An input of pH and TCO 2 yields values of fCO 2 and TA that are in good agreement with the measured values (±22.3 ?atm in fCO 2 and ±4.3 ?mol kg -1 in TA). The cause of the decrease in p K2 at high fCO 2 is presently unknown. The observed inconsistencies between the measured and computed fCO 2 values may be accounted for by adding the effect of organic acid (˜8 ?mol kg -1) to the interpretation of the TA. Further studies are needed to elucidate the chemical reactions responsible for this effect.

Millero, Frank J.; Pierrot, Denis; Lee, Kitack; Wanninkhof, Rik; Feely, Richard; Sabine, Christopher L.; Key, Robert M.; Takahashi, Taro

2002-10-01

294

Modeling the absorption of weak electrolytes and acid gases with ionic liquids using the soft-SAFT approach.  

PubMed

In this work, the solubility of three common pollutants, SO(2), NH(3), and H(2)S, in ionic liquids (ILs) is studied using the soft-SAFT equation of state with relatively simple models. Three types of imidazolium ionic liquids with different anions are described in a transferable manner using the recently published molecular models (Andreu, J. S.; Vega, L. F. J. Phys. Chem. C 2007, 111, 16028; Llovell et al. J. Phys. Chem. B 2011, 115, 4387), whereas new models for SO(2), NH(3), and H(2)S are proposed here. Alkyl-imidazolium ionic liquids with the [PF(6)](-) and [BF(4)](-) anions are considered to be Lennard-Jones chainlike molecules with one associating site in each molecule describing the specific cation-anion interactions. Conversely, the cation and anion forming the imidazolium [Tf(2)N](-) ionic liquids are modeled as a single molecule with three associating sites, taking into account the delocalization of the anion electric charge due to the presence of oxygen groups surrounding the nitrogen of the anion. NH(3) is described with four associating sites: three sites of type H mimicking the hydrogen atoms and one site of type e representing the lone pair of electrons. H(2)S is modeled with three associating sites: two for the sites of type H for the hydrogen atoms and one site of type e for the electronegativity of the sulfur. SO(2) is modeled with two sites, representing the dipole moment of the molecule as an associative interaction. Soft-SAFT calculations with the three models for the pollutants provide very good agreement with the available phase equilibria, enthalpy of vaporization, and heat capacity experimental data. Then, binary mixtures of these compounds with imidazolium-based ionic liquids were calculated in an industrially relevant temperature range. Unlike association interactions between the ionic liquids and the pollutant gases have been explicitly accounted for using an advanced association scheme. A single temperature independent energy binary parameter is sufficient to describe every family of mixtures in good agreement with the available data in the literature. In addition, a vapor-liquid-liquid equilibrium (VLLE) region, never measured experimentally, has been identified for mixtures of hydrogen sulfide + imidazolium ionic liquids with the [PF(6)](-) anion at high H(2)S concentrations. This work illustrates that relatively simple models are able to capture the phase absorption diagram of different gases in ionic liquids, provided accurate models are available for the pure components as well as an accurate equation of state to model the behavior of complex systems. PMID:22663142

Llovell, F; Marcos, R M; MacDowell, N; Vega, L F

2012-07-01

295

Biological effects of short, high-level exposure to gases: carbon monoxide. Phase report, May 1979-May 1980  

SciTech Connect

This report presents an analysis and synthesis of the available literature describing health and performance effects of exposure to carbon monoxide (CO). The US Army's concern is with high-level, short-term exposures that may exceed present threshold limit values of the American Conference of Governmental Industrial Hygienists (50 ppm as a TWA and a ceiling of 400 ppm for 15 minutes). The organs primarily affected by exposure to CO are the heart and brain, with effects caused by impaired oxygen delivery. During brief exposures to concentrations of up to 35,600 ppm, there was an electrocardiographic change suggestive of myocardial ischemia within 15 seconds after the start of exposure, although there were no changes in heart rate, blood pressure or blood chemistry values in young healthy subjects. The first subjective sign of CO toxicity will probably be a headache followed by a awareness of a pounding heartbeat.

Nightingale, T.E.

1980-06-01

296

Preparation of a carbon-based solid acid catalyst by sulfonating activated carbon in a chemical reduction process.  

PubMed

Sulfonated (SO(3)H-bearing) activated carbon (AC-SO(3)H) was synthesized by an aryl diazonium salt reduction process. The obtained material had a SO(3)H density of 0.64 mmol·g-1 and a specific surface area of 602 m2·g-1. The catalytic properties of AC-SO(3)H were compared with that of two commercial solid acid catalysts, Nafion NR50 and Amberlyst-15. In a 10-h esterification reaction of acetic acid with ethanol, the acid conversion with AC-SO(3)H (78%) was lower than that of Amberlyst-15 (86%), which could be attributed to the fact that the SO(3)H density of the sulfonated carbon was lower than that of Amberlyst-15 (4.60 mmol·g-1). However, AC-SO(3)H exhibited comparable and even much higher catalytic activities than the commercial catalysts in the esterification of aliphatic acids with longer carbon chains such as hexanoic acid and decanoic acid, which may be due to the large specific surface area and mesoporous structures of the activated carbon. The disadvantage of AC-SO(3)H is the leaching of SO(3)H group during the reactions. PMID:20956883

Liu, Xiao-Yan; Huang, Miao; Ma, Hai-Long; Zhang, Zeng-Qiang; Gao, Jin-Ming; Zhu, Yu-Lei; Han, Xiao-Jin; Guo, Xiang-Yun

2010-01-01

297

The Formation and Stability of Carbonic Acid on Outer Solar System Bodies  

NASA Technical Reports Server (NTRS)

The radiation chemistry, thermal stability, and vapor pressure of solid-phase carbonic acid (H2CO3) have been studied with mid-infrared spectroscopy. A new procedure for measuring this molecule's radiation stability has been used to obtain intrinsic IR band strengths and half-lives for radiolytic destruction. Results are compared to literature values. We report, for the first time, measurements of carbonic acid's vapor pressure and its heat of sublimation. We also report the first observation of a chemical reaction involving solid-phase carbonic acid. Possible applications of these findings are discussed, with an emphasis on the outer Solar System.

Peeters, Z.; Hudson, R. L.; Moore, M. H.; Lewis, Ariel

2009-01-01

298

Carbon Isotopes in Unsaturated-Zone Gases and Ground Water Near a Radioactive-Waste Disposal Area, Amargosa Desert Research Site, Nye County, Nevada  

NASA Astrophysics Data System (ADS)

To test hypotheses about radionuclide distribution and transport, vertical profiles of 14C in carbon dioxide were determined on gas samples from a 110-m deep unsaturated zone 32, 100, and 3,000 m from a low-level radioactive-waste disposal area. A direct-scintillation-counting method for radiocarbon was developed that minimized sample handling and compared favorably with the more labor-intensive benzene-synthesis method. Values of ? 13C in pore gas were determined by isotope ratio mass spectrometry. Gross gas compositions were determined by chromatography. Gross gas compositions 100 m from the disposal area were similar to those at the 3,000-m site, i.e., relatively unperturbed, except that O2 levels at the 100-m site were slightly depleted in the 34-48 m depth interval ( ~19.5% versus ~20.8% O2 by volume). Radiocarbon levels at the 100-m site peaked at ~2,000 percent modern carbon (PMC) near land surface and decreased monotonically to <100 PMC at depths below 58 m. Gross gas composition 32 m from the disposal area displayed a well-defined CO2 peak that reached 2.0-2.5% by volume at a depth of 24 m. 14C levels showed a roughly coincident peak that reached 6x105 PMC at the 24 m depth. Elevated levels of tritium and volatile organic-carbon compounds accompanied the CO2 and 14C peaks. Corresponding ? 13CO2 values were shifted -7 to -10 permil from unperturbed values. This shift to lighter values is suggestive of fractionation during microbial production of 14CO2 from disposed waste. Core samples from the affected depths were dry and virtually devoid of microbes, with <4x103 colony forming units per gram of sediment, suggesting that the hypothesized microbial activity occurs closer to the emplacement trenches. Ground water at the 32-m site had a 14C level in dissolved inorganic carbon of 845 PMC in March 2000. Ground water from an adjacent well had a 14C level of 26 PMC in 1989 and 323 PMC in 1999. The low levels of 14C in ground water relative to those in unsaturated-zone gases suggest that radiocarbon transport is primarily by lateral gas diffusion through the unsaturated zone at this site.

Stonestrom, D. A.; Michel, R. L.; Evans, W. C.; Smith, T. R.; Smith, T. R.; Prudic, D. E.; Striegl, R. G.; Haas, H.; Brockman, F. J.; Andraski, B. J.

2001-12-01

299

Atmospheric carbon dioxide retrieved from the Greenhouse gases Observing SATellite (GOSAT): Comparison with ground-based TCCON observations and GEOS-Chem model calculations  

NASA Astrophysics Data System (ADS)

We retrieved column-averaged dry air mole fractions of atmospheric carbon dioxide (XCO2) from backscattered short-wave infrared (SWIR) sunlight measured by the Japanese Greenhouse gases Observing SATellite (GOSAT). Over two years of XCO2 retrieved from GOSAT is compared with XCO2 inferred from collocated SWIR measurements by seven ground-based Total Carbon Column Observing Network (TCCON) stations. The average difference between GOSAT and TCCON XCO2 for individual TCCON sites ranges from -0.87 ppm to 0.77 ppm with a mean value of 0.1 ppm and standard deviation of 0.56 ppm. We find an average bias between all GOSAT and TCCON XCO2 retrievals of -0.20 ppm with a standard deviation of 2.26 ppm and a correlation coefficient of 0.75. One year of XCO2 was retrieved from GOSAT globally, which was compared to global 3-D GEOS-Chem chemistry transport model calculations. We find that the latitudinal gradient, seasonal cycles, and spatial variability of GOSAT and GEOS-Chem agree well in general with a correlation coefficient of 0.61. Regional differences between GEOS-Chem model calculations and GOSAT observations are typically less than 1 ppm except for the Sahara and central Asia where a mean difference between 2 to 3 ppm is observed, indicating regional biases in the GOSAT XCO2 retrievals unobserved by the current TCCON network. Using a bias correction scheme based on linear regression these regional biases are significantly reduced, approaching the required accuracy for surface flux inversions.

Cogan, A. J.; Boesch, H.; Parker, R. J.; Feng, L.; Palmer, P. I.; Blavier, J.-F. L.; Deutscher, N. M.; Macatangay, R.; Notholt, J.; Roehl, C.; Warneke, T.; Wunch, D.

2012-11-01

300

Use of molecular modeling to determine the interaction and competition of gases within coal for carbon dioxide sequestration  

SciTech Connect

Molecular modeling was employed to both visualize and probe our understanding of carbon dioxide sequestration within a bituminous coal. A large-scale (>20,000 atoms) 3D molecular representation of Pocahontas No. 3 coal was generated. This model was constructed based on a the review data of Stock and Muntean, oxidation and decarboxylation data for aromatic clustersize frequency of Stock and Obeng, and the combination of Laser Desorption Mass Spectrometry data with HRTEM, enabled the inclusion of a molecular weight distribution. The model contains 21,931 atoms, with a molecular mass of 174,873 amu, and an average molecular weight of 714 amu, with 201 structural components. The structure was evaluated based on several characteristics to ensure a reasonable constitution (chemical and physical representation). The helium density of Pocahontas No. 3 coal is 1.34 g/cm{sup 3} (dmmf) and the model was 1.27 g/cm{sup 3}. The structure is microporous, with a pore volume comprising 34% of the volume as expected for a coal of this rank. The representation was used to visualize CO{sub 2}, and CH{sub 4} capacity, and the role of moisture in swelling and CO{sub 2}, and CH{sub 4} capacity reduction. Inclusion of 0.68% moisture by mass (ash-free) enabled the model to swell by 1.2% (volume). Inclusion of CO{sub 2} enabled volumetric swelling of 4%.

Jeffrey D. Evanseck; Jeffry D. Madura; Jonathan P. Mathews

2006-04-21

301

Preparation and characterization of biomass carbon-based solid acid catalyst for the esterification of oleic acid with methanol.  

PubMed

A solid acid catalyst, prepared by sulfonating carbonized corn straw, was proved to be an efficient and environmental benign catalyst for the esterification of oleic acid and methanol. Various synthetic parameters, such as carbonization temperature and time were systematically examined. It was found that the catalyst exhibited the highest acid density of 2.64 mmol/g by NaOH titration. A quantitative yield (98%) of ester was achieved, using the most active sulfonated catalyst at 333 K with a 7 wt.% catalyst/oleic acid ratio for 4h, at a 7:1 M ratio of methanol/oleic acid, while the commercial available Amberlyst-15 only gave 85% yield under the same reaction condition. PMID:23453798

Liu, Tiantian; Li, Zhilong; Li, Wei; Shi, Congjiao; Wang, Yun

2013-04-01

302

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

303

Calculations of Encapsulation of Amino Acids Inside the (13, 0) Single?walled Carbon Nanotube  

Microsoft Academic Search

Encapsulation of few amino acids inside (13, 0) single?walled carbon nanotube (SWCNT) has been investigated through calculations within DFT?based method. We find that zwitterionic?Gly acid adsorption is bound stronger to the inner surface of the tube in comparison to nonionic?Gly counterparts, as well as on phenylalanine, histidine and cysteine amino acids. The interaction of amino acids with the outer surface

M. D. Ganji

2010-01-01

304

Capacity of activated carbon in the removal of acid dyes subsequent to its thermal treatment  

Microsoft Academic Search

A commercial activated carbon (Prolabo) was subjected to thermal treatment at 400 and 600°C for 2h. Characterization of the parent, and heated products, was carried out by determining the N2\\/77K adsorption isotherms, FTIR spectra, acidic\\/basic sites, and adsorption of iodine, Acid Blue 74 (AB), Acid Red 73 (AR) and Acid Yellow 23 (AY) from aqueous solution. Thermal treatment resulted in

Amina A. Attia; Wafaa E. Rashwan; Soheir A. Khedr

2006-01-01

305

Method for treating combustion exhaust gases  

SciTech Connect

A method for treating exhaust gases generated by incinerating industrial wastes in a combustion chamber leading to a reaction chamber is described, comprising the steps of: (a) introducing the exhaust gases from the combustion chamber to the reaction chamber while keeping a high temperature; (b) spraying the exhaust gases flowing through the reaction chamber with water to vaporize the water with the heat of the exhaust gases, reducing the temperature of the exhaust gases while forming a saturated aqueous vapor of microparticles in intimate contact with noxious materials of the exhaust gases, thereby permitting the vapor microparticles to absorb and collect the noxious materials of the exhaust graft to form an acidic, saturated aqueous vapor; (c) spraying the acidic, saturated aqueous vapor with a neutralizing agent in a primary neutralization chamber to at least substantially denature the acidic, saturated aqueous vapor to a neutralized waste liquid; and (d) collecting and evacuating the neutralized waste liquid.

Sato, Inomatsu.

1993-05-25

306

USE OF MOLECULAR MODELING TO DETERMINE THE INTERACTION AND COMPETITION OF GASES WITHIN COAL FOR CARBON DIOXIDE SEQUESTRATION  

SciTech Connect

We have made progress in carrying out large scale molecular dynamics simulations using the CHARMM force field in order to refine our coal/guest interactions. There have been two issues facing us over the last year. First, we have had to create a completely new topology and parameter definition for coal. Since we are using a classical force field, we have adopted the strategy of treating coal composed of individual common fragments based upon a distribution of mass, composition, and bonding. Our procedure is similar to treating a protein as being composed of the discrete set of amino acids. Second, we have had to incorporate the quality CO{sub 2} parameters that we have developed over the last two years. There are the geometric and arithmetic procedures, which we have successfully implemented. We have utilized computational molecular modeling to generate a state-of-the-art large scale structural representation of a bituminous coal of low volatile bituminous rank. This structure(s) has been used to investigate the molecular forces between the bituminous coal structure (or idealized pores) and the molecular species CH{sub 4} and CO{sub 2}. We are close to carrying out molecular dynamics simulations, which will allow us to explore and test the newly created model of coal.

Jeffrey D. Evanseck; Jeffry D. Madura; Jonathan P. Mathews

2005-05-27

307

Activated carbon from Eucalyptus camaldulensis Dehn bark using phosphoric acid activation.  

PubMed

The powdered activated carbon prepared by phosphoric acid activation was significantly affected by the carbonization temperature and the weight ratio between raw material and phosphoric acid. With an activation time of 1h and an impregnation ratio of 1:1, the activated carbons with better adsorption capacity were obtained at 500 degrees C. A reduction in the adsorption capacity of the carbon product at higher acid content than this was observed, possibly due to the collapse of the micropore structure. The properties of the resulting activated carbon were: bulk density 0.251gcm(-3), ash content 4.88%, yield 26.2%, iodine adsorption 1043mgg(-1), methylene blue adsorption number 427mgg(-1), and BET surface area 1239m2g(-1). PMID:18455392

Patnukao, Phussadee; Pavasant, Prasert

2008-11-01

308

Carbonic Acid as a Reserve of Carbon Dioxide on Icy Moons: The Formation of Carbon Dioxide (CO2) in a Polar Environment  

NASA Astrophysics Data System (ADS)

Carbon dioxide (CO2) has been detected on the surface of several icy moons of Jupiter and Saturn via observation of the ?3 band with the Near-Infrared Mapping Spectrometer on board the Galileo spacecraft and the Visible-Infrared Mapping Spectrometer on board the Cassini spacecraft. Interestingly, the CO2 band for several of these moons exhibits a blueshift along with a broader profile than that seen in laboratory studies and other astrophysical environments. As such, numerous attempts have been made in order to clarify this abnormal behavior; however, it currently lacks an acceptable physical or chemical explanation. We present a rather surprising result pertaining to the synthesis of carbon dioxide in a polar environment. Here, carbonic acid was synthesized in a water (H2O)-carbon dioxide (CO2) (1:5) ice mixture exposed to ionizing radiation in the form of 5 keV electrons. The irradiated ice mixture was then annealed, producing pure carbonic acid which was then subsequently irradiated, recycling water and carbon dioxide. However, the observed carbon dioxide ?3 band matches almost exactly with that observed on Callisto; subsequent temperature program desorption studies reveal that carbon dioxide synthesized under these conditions remains in solid form until 160 K, i.e., the sublimation temperature of water. Consequently, our results suggest that carbon dioxide on Callisto as well as other icy moons is indeed complexed with water rationalizing the shift in peak frequency, broad profile, and the solid state existence on these relatively warm moons.

Jones, Brant M.; Kaiser, Ralf I.; Strazzulla, Giovanni

2014-06-01

309

Molten Carbonate and Phosphoric Acid Stationary Fuel Cells: Overview and Gap Analysis  

SciTech Connect

This report describes the technical and cost gap analysis performed to identify pathways for reducing the costs of molten carbonate fuel cell (MCFC) and phosphoric acid fuel cell (PAFC) stationary fuel cell power plants.

Remick, R.; Wheeler, D.

2010-09-01

310

Molten Carbonate and Phosphoric Acid Stationary Fuel Cells: Overview and Gap Analysis.  

National Technical Information Service (NTIS)

This report describes the technical and cost gap analysis performed to identify pathways for reducing the costs of molten carbonate fuel cell (MCFC) and phosphoric acid fuel cell (PAFC) stationary fuel cell power plants.

D. Wheeler R. Remick

2010-01-01

311

Biosynthesis of delta-aminolevulinic acid from the intact carbon skeleton of glutamic acid in greening barley.  

PubMed Central

The customary route in animals and bacteria for delta-aminolevulinic acid biosynthesis is from glycine and succinyl CoA, catalyzed by the enzyme delta-aminolevulinic acid synthetase [succinyl-CoA:glycine C-succinyltransferase (decarboxylating), EC 2.3.1.37]. Attempts to demonstrate this route in plants have been unsuccessful. Evidence is given for a new enzymic route of synthesis of delta-aminolevulinic acid in plants. This route involves the incorporation of the intact five-carbon skeleton of glutamic acid into delta-aminolevulinic acid. Demonstration of the new pathway in plants has been made by feeding specifically labeled [14C]glutamic acid to etiolated barley shoots greening in the light. In the presence of levulinate, a competitive inhibitor of delta-aminolevulinic acid dehydrastase [porphobilinogen synthase; delta-aminolevulinate hydro-lyase (adding delta-aminolevulinate and cyclizing); EC 4.2.1.24], delta-aminolevulinate accumulates. The delta-aminolevulinate formed was chemically degraded by periodate to formaldehyde and succinic acid. The C5 (formaldehyde) fragment was separated, as the 5,5-dimethyl-1,3-cyclohexanedione (dimedone) derivative, from the C1-C4 (succinic acid) fragment. The C5 atom contained radioactivity predominantly derived from C1 of glutamic acid. Conversely, the labeled C3 and C4 atoms of glutamic acid were found primarily in the succinic acid (C1-C4) fragment of delta-aminolevulinate. This labeling pattern for delta-aminolevulinic acid is consistent with a biosynthetic route utilizing the intact five-carbon skeleton of alpha-ketoglutarate, glutamate, or glutamine, and is inconsistent with the delta-aminolevulinic acid synthetase pathway utilizing glycine and succinyl CoA as precursors.

Beale, S I; Gough, S P; Granick, S

1975-01-01

312

Calcium stimulation of gastrin and gastric acid secretion: effect of small doses of calcium carbonate  

Microsoft Academic Search

Oral calcium carbonate (0-5 g, pH 9-4) increased serum gastrin and gastric acid output with slight but insignificant change in serum calcium. A similar rise in serum calcium during an intravenous infusion of calcium gluconate failed to increase serum gastrin and gastric acid output. Both intragastric calcium actions were abolished by acidification of the calcium carbonate solution (pH 1-0). The

J Behar; M Hitchings; R D Smyth

1977-01-01

313

Acid Reactivity of Carbonated Apatites with Strontium and Fluoride Substitutions  

Microsoft Academic Search

Carbonated apatites containing approximately 3.0 or 6.5% CO3were precipitated in the presence of sodium, strontium, and\\/or fluoride at various concentrations. Almost all the available strontium and fluoride was incorporated into the crystals, whereas only a portion of the carbonate and sodium present was taken up. When incorporated together, Sr and F improved the crystallinity of carbonated apatites and markedly reduced

J. D. B. Featherstone; C. P. Shields; B. Khademazad; M. D. Oldershaw

1983-01-01

314

Solubility of single gases carbon dioxide and hydrogen sulfide in aqueous solutions of N-methyldiethanolamine in the temperature range 313--413 K at pressures up to 5 MPa  

SciTech Connect

Experimental results for the solubility of the single gases carbon dioxide and hydrogen sulfide in aqueous solutions of 2,2{prime}-methyliminodiethanol (N-methyldiethanolamine (MDEA)) at temperatures between 313 and 413 K and total pressures up to 5 MPa are reported. A model taking into account chemical reactions as well as physical interactions is used to correlate the new data. The correlation is also used to compare the new experimental data with literature data.

Kuranov, G.; Smirnova, N.A. [St. Petersburg State Univ. (Russian Federation). Dept. of Chemistry] [St. Petersburg State Univ. (Russian Federation). Dept. of Chemistry; Rumpf, B.; Maurer, G. [Univ. Kaiserslautern (Germany). Lehrstuhl fuer Technische Thermodynamik] [Univ. Kaiserslautern (Germany). Lehrstuhl fuer Technische Thermodynamik

1996-06-01

315

Solubility of single gases carbon dioxide and hydrogen sulfide in aqueous solutions of N-methyldiethanolamine in the temperature range 313--413 K at pressures up to 5 MPa  

Microsoft Academic Search

Experimental results for the solubility of the single gases carbon dioxide and hydrogen sulfide in aqueous solutions of 2,2â²-methyliminodiethanol (N-methyldiethanolamine (MDEA)) at temperatures between 313 and 413 K and total pressures up to 5 MPa are reported. A model taking into account chemical reactions as well as physical interactions is used to correlate the new data. The correlation is also

George Kuranov; N. A. Smirnova; B. Rumpf; Gerd Maurer

1996-01-01

316

Serum and urine amino acid pattern under the effect of carbon disulfide intoxication  

Microsoft Academic Search

Summary The effect of carbon disulphide intoxication on amino acid pattern was studied. Five groups of rats were treated with carbon disulphide through intramuscular injection of 0.05 ml CS2 in 0.2 ml olive oil\\/rat\\/day. A number of rats were sacrified after receiving 10, 20, 30, 40, and 50 injections.

E. A. El-Dessouky; M. F. S. Hawary; F. A. El-Shobaki; Z. El-Hawary; A. A. Massoud

1977-01-01

317

Role of sulfonic acids in the Sn-catalyzed transesterification of dimethyl carbonate with phenol  

Microsoft Academic Search

Diphenyl carbonate, the key intermediate of the non-phosgene polycarbonate manufacturing process, can be produced by the transesterification of dimethyl carbonate with phenol in the presence of dibutyltin oxide. The use of an alkyl or aryl sulfonic acid in conjunction with dibutyltin oxide significantly enhances the activity of dibutyltin oxide. 19F and 119Sn NMR studies suggest the formation of tin complex

Hyunjoo Lee; Sung Joon Kim; Byoung Sung Ahn; Won Koo Lee; Hoon Sik Kim

2003-01-01

318

Activated Carbon from Peach Stones Using Phosphoric Acid Activation at Medium Temperatures  

Microsoft Academic Search

In the present study, the activation features of phosphoric acid have been investigated using waste peach stones as the raw material in the production of granular activated carbon. Thermogravimetry\\/differential thermal analysis was conducted to characterize the thermal behavior of peach stone and titration method was used to evaluate the adsorption capacity of the produced activated carbon. It was observed that

Dong-Su Kim

2004-01-01

319

USE OF THE COMPOSITION AND STABLE CARBONIISOTOPE RATIO OF MICROBIAL FATTY ACIDS TO STUDY CARBON CYCLING  

EPA Science Inventory

We use measurements of the concentration and stable carbon isotopic ratio (*13C) of individual microbial phospholipid fatty acids (PLFAs) in soils and sediments as indicators of live microbial biomass levels and microbial carbon source. For studies of soil organic matter (SOM) cy...

320

Production of activated carbon from a new precursor molasses by activation with sulphuric acid  

Microsoft Academic Search

Activated carbon has been prepared from molasses, a natural precursor of vegetable origin resulting from the sugar industry in Morocco. The preparation of the activated carbon from the molasses has been carried out by impregnation of the precursor with sulphuric acid, followed by carbonisation at varying conditions (temperature and gas coverage) in order to optimize preparation parameters. The influence of

K. Legrouri; E. Khouya; M. Ezzine; H. Hannache; R. Denoyel; R. Pallier; R. Naslain

2005-01-01

321

Lipase-catalyzed esterification of rutin and naringin with fatty acids of medium carbon chain  

Microsoft Academic Search

Flavonoids rutin and naringin were acylated with fatty acids of medium carbon chain (with 8–12 carbon atoms on their molecule) in a reaction catalyzed by immobilized lipase from Candida antarctica (Novozyme) in various solvent systems. The reaction parameters affecting the acylation rate and the conversion of the enzymatic process, such as the nature of the organic solvent and acyl donor

A Kontogianni; V Skouridou; V Sereti; H Stamatis; F. N Kolisis

2003-01-01

322

The role of carbon in valve-regulated lead–acid battery technology  

Microsoft Academic Search

The properties of different forms of carbon and their potential, as active mass additives, for influencing the performance of valve-regulated lead–acid batteries are reviewed. Carbon additives to the positive active-mass appear to benefit capacity, but are progressively lost due to oxidation. Some forms of carbon in the negative active-material are able to resist the tendency to sulfation during high-rate partial-state-of-charge

P. T. Moseley; R. F. Nelson; A. F. Hollenkamp

2006-01-01

323

Degradation and removal of naphthalenesulphonic acids by means of adsorption and ozonation catalyzed by activated carbon in water  

Microsoft Academic Search

Studies were conducted on the efficiency of systems based on the use of ozone, activated carbon, and ozone\\/activated carbon in the treatment of waters containing 1-naphthalenesulphonic acid, 1,5-naphthalenedisulphonic acid, and 1,3,6-naphthalenetrisulphonic acid. In the removal of these acids by adsorption on activated carbon the elevated heights of the mass transfer zone columns and the low values of the breakthrough volumes

J. Rivera-Utrilla; M. Sánchez-Polo

2003-01-01

324

Thermal infrared nadir observations of 24 atmospheric gases  

NASA Astrophysics Data System (ADS)

Thermal infrared nadir sounders are ideal for observing total columns or vertical profiles of atmospheric gases such as water, carbon dioxide and ozone. High resolution sounders with a spectral resolution below 5 cm-1 can distinguish fine spectral features of trace gases. Forty years after the launch of the first hyperspectral sounder IRIS, we have now several state of the art instruments in orbit, with improved instrumental specifications. In this letter we give an overview of the trace gases which have been observed by infrared nadir sounders, focusing on new observations of the Infrared Atmospheric Sounding Interferometer (IASI). We present typical observations of 14 rare reactive trace gas species. Several species are reported here for the first time in nadir view, including nitrous acid, furan, acetylene, propylene, acetic acid, formaldehyde and hydrogen cyanide, observations which were made in a pyrocumulus cloud from the Australian bush fires of February 2009. Being able to observe this large number of reactive trace gases will likely improve our knowledge of source emissions and their impact on the environment and climate.

Clarisse, Lieven; R'Honi, Yasmina; Coheur, Pierre-François; Hurtmans, Daniel; Clerbaux, Cathy

2011-05-01

325

Preparation of a novel carbon-based solid acid from cassava stillage residue and its use for the esterification of free fatty acids in waste cooking oil.  

PubMed

A novel carbon-based solid acid catalyst was prepared by the sulfonation of incompletely carbonized cassava stillage residue (CSR) with concentrated sulfuric acid, and employed to catalyze the esterification of methanol and free fatty acids (FFAs) in waste cooking oil (WCO). The effects of the carbonization and the sulfonation temperatures on the pore structure, acid density and catalytic activity of the CSR-derived catalysts were systematically investigated. Low temperature carbonization and high temperature sulfonation can cause the collapse of the carbon framework, while high temperature carbonization is not conducive to the attachment of SO3H groups on the surface. The catalyst showed high catalytic activity for esterification, and the acid value for WCO is reduced to below 2mg KOH/g after reaction. The activity of catalyst can be well maintained after five cycles. CSR can be considered a promising raw material for the production of a new eco-friendly solid acid catalyst. PMID:24661813

Wang, Lingtao; Dong, Xiuqin; Jiang, Haoxi; Li, Guiming; Zhang, Minhua

2014-04-01

326

The recommended dissociation constants for carbonic acid in seawater  

NASA Astrophysics Data System (ADS)

A coherent representation of carbonate dissociation constants and measured inorganic carbon species is essential for a wide range of environmentally important issues such as oceanic uptake of anthropogenic CO2 and carbon cycle depictions in ocean circulation models. Previous studies have shown varying degrees of discordance between calculated and measured CO2-system parameters. It is unclear if this is due to errors in thermodynamic models or in measurements. In this work, we address this issue using a large field dataset (15,300 water samples) covering all ocean basins. Our field data, obtained using laboratory-calibrated measurement protocols, are most consistent with calculated parameters using the dissociation constants of Mehrbach et al. [1973] as refit by Dickson and Millero [1987]. Thus, these constants are recommended for use in the synthesis of the inorganic carbon data collected during the global CO2 survey during the 1990s and for characterization of the carbonate system in seawater.

Lee, Kitack; Millero, Frank J.; Byrne, Robert H.; Feely, Richard A.; Wanninkhof, Rik

327

Reporting emissions of greenhouse gases in Canada  

Microsoft Academic Search

Non-carbon dioxide greenhouse gases are considered in “Canada's National Report on Climate Change: Actions to Meet Commitments Under the United Nations Framework Convention on Climate Change”. By including all major greenhouse gases and their anthropogenic sources and sinks using best available science, the Report provides a practical illustration of the “comprehensive approach” policy to implementing the Convention's requirements. In addition

Patrick Finlay; Robert Stobbs

1994-01-01

328

Voluntary Reporting of Greenhouse Gases Archive  

EIA Publications

The Voluntary Reporting of Greenhouse Gases Program established a mechanism by which corporations, government agencies, individuals, voluntary organizations, etc., can report to the EIA, any actions taken that have or are expected to reduce/avoid emissions of greenhouse gases or sequester carbon.

Information Center

2011-02-01

329

Oxygen-18 incorporation into malic acid during nocturnal carbon dioxide fixation in crassulacean acid metabolism plants: a new approach to estimating in vivo carbonic anhydrase activity  

SciTech Connect

Crassulacean acid metabolism (CAM) plants fix carbon dioxide at night by the carboxylation of phosphoenolpyruvate. If CO2 fixation is conducted with TC YO2, then in the absence of carbonic anhydrase, the malate formed by dark CO2 fixation should also contain high levels of carbon-13 and oxygen-18. Conversely, if carbonic anhydrase is present and highly active, oxygen exchange between CO2 and cellular H2O will occur more rapidly than carboxylation, and the ( TC) malate formed will contain little or no oxygen-18 above the natural abundance level. The presence of oxygen-18 in these molecules can be detected either by nuclear magnetic resonance or by mass spectrometry. Studies of phosphoenolpyruvate carboxylase in the presence and absence of carbonic anhydrase in vitro confirm the validity of the method. When CAM plants are studied by this method, we find that most species show incorporation of a significant amount of oxygen-18. Comparison of these results with results of isotope fractionation and gas exchange studies permits calculation of the in vivo activity of carbonic anhydrase toward HCO3 compared with that of phosphoenolpyruvate carboxylase. The ratio (carbonic anhydrase activity/phosphoenolpyruvate carboxylase activity) is species dependent and varies from a low of about 7 for Ananas comosus to values near 20 for Hoya carnosa and Bryophyllum pinnatum, 40 for Kalanchoee daigremontiana, and 100 or greater for Bryophyllum tubiflorum, Kalanchoee serrata, and Kalanchoae tomentosa. Carbonic anhydrase activity increases relative to phosphoenolpyruvate carboxylase activity at higher temperature. 37 references, 2 figures, 8 tables.

Holtum, J.A.M.; Summons, R.; Roeske, C.A.; Comins, H.N.; O'Leary, M.H.

1984-01-01

330

Carbon isotope and abundance systematics of Icelandic geothermal gases, fluids and subglacial basalts with implications for mantle plume-related CO2 fluxes  

NASA Astrophysics Data System (ADS)

We report new carbon dioxide (CO2) abundance and isotope data for 71 geothermal gases and fluids from both high-temperature (HT > 150 °C at 1 km depth) and low-temperature (LT < 150 °C at 1 km depth) geothermal systems located within neovolcanic zones and older segments of the Icelandic crust, respectively. These data are supplemented by CO2 data obtained by stepped heating of 47 subglacial basaltic glasses collected from the neovolcanic zones. The sample suite has been characterized previously for He-Ne (geothermal) and He-Ne-Ar (basalt) systematics (Füri et al., 2010), allowing elemental ratios to be calculated for individual samples. Geothermal fluids are characterized by a wide range in carbon isotope ratios (?13C), from -18.8‰ to +4.6‰ (vs. VPDB), and CO2/3He values that span eight orders of magnitude, from 1 × 104 to 2 × 1012. Extreme geothermal values suggest that original source compositions have been extensively modified by hydrothermal processes such as degassing and/or calcite precipitation. Basaltic glasses are also characterized by a wide range in ?13C values, from -27.2‰ to -3.6‰, whereas CO2/3He values span a narrower range, from 1 × 108 to 1 × 1012. The combination of both low ?13C values and low CO2 contents in basalts indicates that magmas are extensively and variably degassed. Using an equilibrium degassing model, we estimate that pre-eruptive basaltic melts beneath Iceland contain ?531 ± 64 ppm CO2 with ?13C values of -2.5 ± 1.1‰, in good agreement with estimates from olivine-hosted melt inclusions (Metrich et al., 1991) and depleted MORB mantle (DMM) CO2 source estimates (Marty, 2012). In addition, pre-eruptive CO2 compositions are estimated for individual segments of the Icelandic axial rift zones, and show a marked decrease from north to south (Northern Rift Zone = 550 ± 66 ppm; Eastern Rift Zone = 371 ± 45 ppm; Western Rift Zone = 206 ± 24 ppm). Notably, these results are model dependent, and selection of a lower ?13C fractionation factor will result in lower source estimates and larger uncertainties associated with the initial ?13C estimate. Degassing can adequately explain low CO2 contents in basalts; however, degassing alone is unlikely to generate the entire spectrum of observed ?13C variations, and we suggest that melt-crust interaction, involving a low ?13C component, may also contribute to observed signatures. Using representative samples, the CO2 flux from Iceland is estimated using three independent methods: (1) combining measured CO2/3He values (in gases and basalts) with 3He flux estimates (Hilton et al., 1990), (2) merging basaltic emplacement rates of Iceland with pre-eruptive magma source estimates of ?531 ± 64 ppm CO2, and (3) combining fluid CO2 contents with estimated regional fluid discharge rates. These methods yield CO2 flux estimates from of 0.2-23 × 1010 mol a-1, which represent ?0.1-10% of the estimated global ridge flux (2.2 × 1012 mol a-1; Marty and Tolstikhin, 1998).

Barry, P. H.; Hilton, D. R.; Füri, E.; Halldórsson, S. A.; Grönvold, K.

2014-06-01

331

Electrochemical behaviors of amino acids at multiwall carbon nanotubes and Cu2O modified carbon paste electrode.  

PubMed

A carbon paste electrode modified with multiwall carbon nanotubes and copper(I) oxide (MWCNT-Cu(2)O CPME) was fabricated, and the electrochemical behaviors of 19 kinds of natural amino acids at this modified electrode were studied. The experimental results showed that the various kinds of amino acids without any derivatization displayed obvious oxidation current responses at the modified electrode. It was also found that the current response values of amino acids were dependent mainly on pH values of buffer solutions. The phenomenon could be explained by the fact that the amino acids suffered complexation or electrocatalytic oxidation processes under different pH values. Six kinds of amino acids (arginine, tryptophan, histidine, threonine, serine, and tyrosine), which performed high-oxidation current responses in alkaline buffers, were selected to be detected simultaneously by capillary zone electrophoresis coupled with amperometric detection (CZE-AD). These amino acids could be perfectly separated within 20 min, and their detection limits were as low as 10(-7) or 10(-8)mol L(-1) magnitude (signal/noise ratio=3). The above results demonstrated that MWCNT-Cu(2)O CPME could be successfully employed as an electrochemical sensor for amino acids with some advantages of convenient preparation, high sensitivity, and good repeatability. PMID:18522798

Dong, Shuqing; Zhang, Shan; Chi, Langzhu; He, Pingang; Wang, Qingjiang; Fang, Yuzhi

2008-10-15

332

An Examination of the Carbon Isotope Effects Associated with Amino Acid Biosynthesis  

Microsoft Academic Search

Stable carbon isotope ratios (delta13C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glutamine), lysine, serine, glycine, and threonine from metabolically diverse microorganisms. The microorganisms examined included fermenting bacteria, organotrophic, chemolithotrophic, phototrophic, methylotrophic, methanogenic, acetogenic, acetotrophic, and naturally occurring cryptoendolithic communities from the Dry Valleys of Antarctica. Here we demonstrated

James H. Scott; Diane M. O'Brien; David Emerson; Henry Sun; Gene D. McDonald; Antonio Salgado; Marilyn L. Fogel

2006-01-01

333

Research Paper An Examination of the Carbon Isotope Effects Associated with Amino Acid Biosynthesis  

Microsoft Academic Search

Stable carbon isotope ratios (? 13C) were determined for alanine, proline, phenylalanine, valine, leucine, isoleucine, aspartate (aspartic acid and asparagine), glutamate (glutamic acid and glu- tamine), lysine, serine, glycine, and threonine from metabolically diverse microorganisms. The microorganisms examined included fermenting bacteria, organotrophic, chemolithotrophic, phototrophic, methylotrophic, methanogenic, acetogenic, acetotrophic, and naturally occurring cryptoendolithic communities from the Dry Valleys of Antarctica. Here

JAMES H. SCOTT; DIANE M. O'BRIEN; DAVID EMERSON; HENRY SUN; GENE D. McDONALD; ANTONIO SALGADO; MARILYN L. FOGEL

334

CARBON STEEL CORROSION IN HIGHLY CONCENTRATED NITRIC ACID CONTAINING HALOGEN COMPOUNDS  

Microsoft Academic Search

Iodine and its compounds are effective inhibitors against corrosion of ; carbon steel in highly concentrated nitric acid. The protective action remains ; effectiv-e in boiling acid solutions however the protective action is not ; effective in the vapor phase. The oxidation-reduction potentials of HNOâ ; do not change with iodine admixtures. (R.V.J.);

I. P. Mukanov; S. D. Beskov

1961-01-01

335

Reaction rate vs. transport limited dissolution during carbonate acidizing: Application of network model  

Microsoft Academic Search

Coreflood experiments have been performed and a two dimensional network model has been developed to study the flow, dissolution, and permeability increase in carbonates during acid stimulation treatments. The goal is to be able to predict the behaviour of the random flow channels, called wormholes, that form in the rock as a result of acid attack. Understanding this channeling phenomenon

M. L. Hoefner; H. S. Fogler

1986-01-01

336

PERFORMANCE AND MODELING OF A HOT POTASSIUM CARBONATE ACID GAS REMOVAL SYSTEM IN TREATING COAL GAS  

EPA Science Inventory

The report discusses the performance and modeling of a hot potassium carbonate (K2CO3) acid gas removal system (AGRS) in treating coal gas. Aqueous solutions of K2CO3, with and without amine additive, were used as the acid gas removal solvent in the Coal Gasification/Gas Cleaning...

337

Polyvinylpyrrolidone and polyethylenimine as inhibitors for the corrosion of a low carbon steel in phosphoric acid  

Microsoft Academic Search

Polarization and weight loss studies showed that both polyvinylpyrrolidonc and polyethylenimine are effective for the inhibition of low carbon steel over a wide concentration range of aqueous phosphoric acid (H3PO4) solutions. Both polymers retard the anodic and cathodic corrosion reactions with emphasis on the former. The results for uninhibited acid confirm the kinetic expression proposed by Mathur and Vasudevan.

Y. Jianguo; W. Lin; V. Otieno-Alego; D. P. Schweinsberg

1995-01-01

338

Dispersion of single-walled carbon nanotubes in alcohol-cholic acid mixtures  

NASA Astrophysics Data System (ADS)

A procedure for dispersing single-walled carbon nanotubes (SWNTs) for the preparation of suspensions with high concentrations of individual nanotubes in various solvents was described. The most stable suspensions were obtained from a mixture of ethanol with cholic acid at an acid concentration of 0.018 mol/kg.

Dyshin, A. A.; Eliseeva, O. V.; Bondarenko, G. V.; Kolker, A. M.; Zakharov, A. G.; Fedorov, M. V.; Kiselev, M. G.

2013-12-01

339

Physical solubility of hydrogen sulfide and carbon dioxide in alkanolamine solutions  

Microsoft Academic Search

The study was undertaken to develop a method that would make direct measurements of acid gases, hydrogen sulfide and carbon dioxide, physical solubilities in aqueous alkanolamine solutions possible. Hydrogen sulfide and carbon dioxide physical solubilities in 20, 35, and 50% by weight diethanolamine aqueous solutions were measured. The solubility measurements were made at acid gas partial pressure up to 1000

Abu-Arabi

1988-01-01

340

Concentration Effect of Palm Oil Fatty Acid on Curing Characteristics and Mechanical Properties of Carbon Black Filled Natural Rubber Compounds  

Microsoft Academic Search

The concentration effect of palm oil fatty acid on curing characteristics and mechanical properties of carbon black filled natural rubber compounds was investigated. Results indicate that maximum torque increases with palm oil fatty acid concentration for all carbon black loadings investigated. Natural rubber compounds with 50 phr of carbon black show highest maximum torque. Scorch time and cure time (t90)

Hanafi Ismail; T. A. Ruhaizat

1997-01-01

341

Highly ordered three dimensional macroporous carbon spheres and their acid catalytic properties  

NASA Astrophysics Data System (ADS)

Highly ordered three dimensional macroporous carbon spheres bearing sulfonic acid groups (MPCS-SO3H) were prepared by incomplete carbonization of glucose in silica crystal bead template, followed by sulfonation and removal of the template. The composition and porous structure of the obtained carbon spheres were investigated by physical adsorption of nitrogen, scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy techniques. While the Fourier-transform infrared spectroscopy was used to characterize the functional groups on the surface of carbon spheres. The catalytic properties of the MPCS-SO3H were evaluated by esterification of ethanol with acetic acid, indicating that MPCS-SO3H possess remarkable catalytic performance (high stability and acid catalytic ability) for the esterification.

Huang, Hui; Zhang, Jianming; Zhang, Yuxiao; Lian, Suoyuan; Liu, Yang

2013-10-01

342

Preliminary simulations of planned experiments to study the impact of trace gases on the capacity of the Weyburn-Midale field to store carbon dioxide  

SciTech Connect

The CO{sub 2} stream injecting into the Weyburn-Midale field can be generally classified as a reducing stream with residual H{sub 2}S and low-molecular weight hydrocarbons. The composition of the CO{sub 2} gas stream from the Dakota Gasification Company is reported to be 95% CO{sub 2}, 4% hydrocarbons, and 1% H{sub 2}S by volume (Huxley 2006). In addition to the H{sub 2}S introduced at the injection wells, significant concentrations of H{sub 2}S are thought to have been produced in-situ by sulfate reducing bacteria from previous water floods for enhanced oil production. Produced gas compositions range in H{sub 2}S concentrations from 1 to 6 volume percent. The produced gas, including the trace impurities, is re-injected into the field. Although there is no evidence for inorganic reduction of SO{sub 4}{sup 2-} to H{sub 2}S at the Weyburn-Midale field, Sitchler and Kazuba (2009) suggest that SO{sub 4}{sup 2-} can be inorganically reduced to elemental sulfur in highly reducing environments based on a natural analog study of the Madison Formation in Wyoming. They propose that elevated concentrations of CO{sub 2} dissolve anhydrite to produce the sulfate that is then reduced. Oxidizing CO{sub 2} streams with residual O{sub 2} and SO{sub 2} typical of streams captured from oxyfuel and post combustion processes are not presently an issue at the Weyburn-Midale field. However it is possible that the oxidizing CO{sub 2} streams may be injected in the future in carbonate reservoirs similar to the Weyburn-Midale field. To date there are few modeling and experimental studies that have explored the impact of impurity gases in CO{sub 2} streams targeted for geologic storage (Gale 2009). Jacquemet et al (2009) reviewed select geochemical modeling studies that explored the impact of SO{sub 2} and H{sub 2}S impurities in the waste streams (Gunter et al., 2000, Knauss et al., 2005, Xu et al., 2007). These studies collectively show that SO{sub 2} significantly reduces the pH when oxidized to H{sub 2}SO{sub 4} causing enhanced dissolution of carbonate minerals and some sulfate mineral precipitation. Low pH results in higher mineral solubility and faster dissolution rates and is thought to enhance porosity and permeability near the injection well when trace amounts of SO{sub 2} is injected with CO{sub 2}. The impact of H{sub 2}S on storage reservoir performance appears to more subtle. Knauss et al (2005) report no significant impacts of injection of CO{sub 2} gas streams with and without H{sub 2}S (1 M Pascal H{sub 2}S + 8.4 M Pascal CO{sub 2}) in simulations of CO{sub 2} storage in the Frio sandstone formation. Geochemical reactions for H{sub 2}S impurities include enhance field alkalinity and reaction with iron bearing minerals that may delay breakthrough of H{sub 2}S relative to CO{sub 2}. Emberley et al. (2005) report that half of the alkalinity measured at monitoring wells at the Weyburn-Midale field is due to HS{sup -}. Schoonen and Xu (2004) report that H{sub 2}S can be sequestered as pyrite in sandstones and carbonates by dissolving iron hydroxides and iron-bearing clays. Similarly, Gunter et al (2000) propose the that siderite converts to iron sulfides when it is reacted with H{sub 2}S. The geochemical reactions between H{sub 2}S and iron bearing minerals together with the high solubility of H{sub 2}S relative to CO{sub 2} may contribute to the delayed break though of H{sub 2}S in experiments. A few core flood experiments have shown that the injection of supercritical CO{sub 2} into carbonate aquifers has the potential to significantly alter the porosity in the absence of trace gases such as SO{sub 2} and H{sub 2}S. Luquot and Gouze (2009) documented a 2% porosity increase in carbonate cores when rock-water interactions were transport limited and solution concentrations were closer to equilibrium and a 4% porosity increase when rock-water interactions were reaction limited and solution compositions were further from equilibrium. Similarly Le Guen et al (2007) used x-ray micro-tomography and geochemistry to show that porosity signific

Carroll, S; Hao, Y

2009-11-13

343

Interaction of organic acids with carbonate mineral surfaces in seawater and related solutions: I. Fatty acid adsorption  

NASA Astrophysics Data System (ADS)

The adsorption of C 4 to C 18 fatty acid anion homologs from seawater and related solutions was examined on calcite, aragonite, dolomite and magnesite surfaces. Butyrate, octanoate and laurate did not adsorb, while myristate, palmitate and stearate adsorbed on all carbonate surfaces. An increasing affinity for carbonate surfaces was found with increasing alkyl chain length for these fatty acids. Adsorption at low concentrations typical of marine waters is controlled by surface adsorption sites. At high concentration adsorption is governed by solution composition and limited by aqueous solubility. Adsorption-desorption reactions were characterized by a large resistant component that resulted in nonsingular isotherms. Myristate adsorption was enhanced in the presence of stearate cosorption. Orthophosphate in trace quantities was capable of displacing fatty acids from carbonate surfaces, but contrary to earlier studies, we found no major influence from magnesium ion on adsorption. The results of this study are interpreted in terms of a model based on the different types of forces which contribute to adsorption of these organic compounds. This model emphasizes the importance of organic aqueous solubility and the acid function as criteria controlling the adsorption of natural hydrophobic organics with carbonate mineral surfaces in aqueous fluids.

Zullig, James J.; Morse, John W.

1988-06-01

344

Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System  

PubMed Central

Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1) system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source) and keto acids (oxylic acid sources). In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of life’s origin.

Fujioka, Kouki; Futamura, Yasuhiro; Shiohara, Tomoo; Hoshino, Akiyoshi; Kanaya, Fumihide; Manome, Yoshinobu; Yamamoto, Kenji

2009-01-01

345

Carbon components in the phosphoric acid fuel cell-an overview  

SciTech Connect

The single breakthrough that has made the phosphoric acid fuel cell a practical reality has been the use of carbon or graphite components for the repeat parts of the cell stack. While the thermodynamic stability of carbon is such that rapid corrosion would be expected at the cathode at fuel cell operating temperature, its kinetic stability is remarkable despite the absence of passivating layers analogous to those on, for example, the Group VA elements niobium and tantalum. This happy accident, combined with the adequate electronic conductivity of the carbon materials used, has provided the opportunity to reduce fuel cell cost to attractive levels. The development of these carbon compounds is reviewed.

Appleby, J.

1983-08-01

346

Inhibition Effect of Dodecylamine on Carbon Steel Corrosion in Hydrochloric Acid Solution  

NASA Astrophysics Data System (ADS)

Dodecylamine spontaneously adsorbs on carbon steel via its polar group (-NH2) in hydrochloric acid solution. Furthermore, it forms a monolayer film on carbon steel surface. The inhibition mechanism of dodecylamine for carbon steel is geometric blocking effect. The adsorption of dodecylamine on carbon steel surface follows Arrhenius equation. The adsorption slightly increases activated energy, but greatly reduces pre-exponential factor value. Atomic force microscopy force curves indicate that at the area without adsorbed dodecylamine, no obvious adhere force occurs. At the area with adsorbed dodecylamine, however, an average 1.3 nN adhere force is observed.

Chen, Zhenyu; Huang, Ling; Qiu, Yubing; Guo, Xingpeng

2012-12-01

347

Metabolic carbon fluxes and biosynthesis of polyhydroxyalkanoates in Ralstonia eutropha on short chain fatty acids.  

PubMed

Short chain fatty acids such as acetic, propionic, and butyric acids can be synthesized into polyhydroxyalkanoates (PHAs) by Ralstonia eutropha. Metabolic carbon fluxes of the acids in living cells have significant effect on the yield, composition, and thermomechanical properties of PHA bioplastics. Based on the general knowledge of central metabolism pathways and the unusual metabolic pathways in R. eutropha, a metabolic network of 41 bioreactions is constructed to analyze the carbon fluxes on utilization of the short chain fatty acids. In fed-batch cultures with constant feeding of acid media, carbon metabolism and distribution in R. eutropha were measured involving CO2, PHA biopolymers, and residual cell mass. As the cells underwent unsteady state metabolism and PHA biosynthesis under nitrogen-limited conditions, accumulative carbon balance was applied for pseudo-steady-state analysis of the metabolic carbon fluxes. Cofactor NADP/NADPH balanced between PHA synthesis and the C3/C4 pathway provided an independent constraint for solution of the underdetermined metabolic network. A major portion of propionyl-CoA was directed to pyruvate via the 2-methylcitrate cycle and further decarboxylated to acetyl-CoA. Only a small amount of propionate carbon (<15% carbon) was directly condensed with acetyl-CoA for 3-hydroxyvalerate. The ratio of glyoxylate shunt to TCA cycle varies from 0 to 0.25, depending on the intracellular acetyl-CoA level and acetic acid in the medium. Malate is the node of the C3/C4 pathway and TCA cycle and its decarboxylation to dehydrogenation ranges from 0.33 to 1.28 in response to the demands on NADPH and oxaloacetate for short chain fatty acids utilization. PMID:15296425

Yu, Jian; Si, Yingtao

2004-01-01

348

Greenhouse gases from animal husbandry: mitigation options  

Microsoft Academic Search

Abatement strategies for direct emissions of greenhouse gases from animal husbandry are discussed. The reduction options are\\u000a divided into preventive and `end of pipe' options. Preventive measures reduce either the carbon and nitrogen input into the\\u000a system of animal husbandry or their output from the system, respectively. `End of pipe' measures reduce the formation of greenhouse\\u000a gases from carbon and

Joachim Clemens; Heinz-Jürgen Ahlgrimm

2001-01-01

349

Oxygen-18 incorporation into malic acid during nocturnal carbon dioxide fixation in crassulacean acid metabolism plants. A new approach to estimating in vivo carbonic anhydrase activity.  

PubMed

Crassulacean acid metabolism (CAM) plants fix carbon dioxide at night by the carboxylation of phosphoenolpyruvate. If CO2 fixation is conducted with 13C18O2 , then in the absence of carbonic anhydrase, the malate formed by dark CO2 fixation should also contain high levels of carbon-13 and oxygen-18. Conversely, if carbonic anhydrase is present and highly active, oxygen exchange between CO2 and cellular H2O will occur more rapidly than carboxylation, and the [13C] malate formed will contain little or no oxygen-18 above the natural abundance level. The presence of oxygen-18 in these molecules can be detected either by nuclear magnetic resonance (using the oxygen-18 effect on the carbon-13 chemical shift of the carboxyl carbon) or by mass spectrometry (comparing the ions at three and five units above the molecular weight with that one unit above). Studies of phosphoenolpyruvate carboxylase in the presence and absence of carbonic anhydrase in vitro confirm the validity of the method. When CAM plants are studied by this method, we find that most species show incorporation of a significant amount of oxygen-18. Comparison of these results with results of isotope fractionation and gas exchange studies permits calculation of the in vivo activity of carbonic anhydrase toward HCO-3 compared with that of phosphoenolpyruvate carboxylase. The ratio (carbonic anhydrase activity/phosphoenolpyruvate carboxylase activity) is species dependent and varies from a low of about 7 for Ananas comosus to values near 20 for Hoya carnosa and Bryophyllum pinnatum , 40 for Kalancho ë daigremontiana , and 100 or greater for Bryophyllum tubiflorum , Kalancho ë serrata, and Kalancho ë tomentosa. Carbonic anhydrase activity increases relative to phosphoenolpyruvate carboxylase activity at higher temperature. PMID:6427227

Holtum, J A; Summons, R; Roeske, C A; Comins, H N; O'Leary, M H

1984-06-10

350

Simplified Fixed Bed Design Models for the Adsorption of Acid Dyes on Novel Pine Cone Derived Activated Carbon  

Microsoft Academic Search

A novel activated carbon has been prepared by the activation of ground pine cones using phosphoric acid activation, and the\\u000a nitrogen Brunauer–Emmett–Teller surface area was 869 m2 g?1. Equilibrium isotherms were performed to assess the capacity of the activated carbon using two acidic dyes, namely Acid Blue\\u000a 113 and Acid Black 1. The monolayer equilibrium isotherm capacities of Acid Blue 113 and

Mahdi Hadi; Mohammad Reza Samarghandi; Gordon McKay

2011-01-01

351

Induction by perfluorinated fatty acids with different carbon chain length of peroxisomal ?-oxidation in the liver of rats  

Microsoft Academic Search

The potency of the induction of peroxisomal ?-oxidation was compared between perfluorinated fatty acids (PFCAs) with different carbon chain lengths in the liver of male and female rats. In male rats, perfluoroheptanoic acid (PFHA) has little effect, although perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) potentially induced the activity. By contrast, PFHA and PFOA did not induce

Naomi Kudo; Naoki Bandai; Erika Suzuki; Masanori Katakura; Yoichi Kawashima

2000-01-01

352

Fumaric acid: an overlooked form of fixed carbon in Arabidopsis and other plant species  

SciTech Connect

Photoassimilates are used by plants for production of energy, as carbon skeletons and in transport of fixed carbon between different plant organs. Many studies have been devoted to characterizing the factors that. regulate photoassimilate concentrations in different plant species. Most studies examining photoassimilate concentrations in C{sub 3} plants have focused on analyzing starch and soluble sugars. However, work presented here demonstrates that a number of C{sub 3} plants, including the popular model organism Arabidopsis thaliana (L.) Heynh., and agriculturally important plants, such as soybean [Glycine ma (L.) Merr.], contain significant quantities of furnaric acid. In fact, furnaric acid can accumulate to levels of several mg per g fresh weight in A-abidopsis leaves, often exceeding starch and soluble sugar levels. Furnaric acid is a component of the tricarboxylic acid cycle and, like starch and soluble sugars, can be metabolized to yield energy and carbon skeletons for production of other compounds. Fumaric acid concentrations increase with plant age and light intensity in Arabidopsis leaves. Arabidopsis phloem exudates contain significant quantities of fumaric acid, raising the possibility that fumaric acid may function in carbon transport.

Chia, D.W.; Yoder, T.J.; Reiter, W.D.; Gibson, S.I.

2000-10-01

353

Effect of carbon chain length on esterification of carboxylic acids with methanol using acid catalysis  

Microsoft Academic Search

This paper reports on an investigation into the impact of carboxylic acid chain length on the kinetics of liquid-phase acid-catalyzed esterification. Using sulfuric acid and a commercial Nafion\\/silica composite solid acid catalyst (SAC-13), initial kinetics were measured for the reactions of a series of linear chain carboxylic acids (acetic, propionic, butyric, hexanoic, and caprylic acid) with methanol at 60?°C. It

Yijun Liu; Edgar Lotero; James G. Goodwin

2006-01-01

354

Carbon isotope composition of dissolved humic and fulvic acids in the Tokachi River system.  

PubMed

This study reports carbon isotopic ratios (?(14)C and ?(13)C) of dissolved humic and fulvic acids in the Tokachi River system, northern Japan. These acids have a refractory feature and they represent the largest fraction of dissolved organic matter in aquatic environments. The acids were isolated using the XAD extraction method from river water samples collected at three sites (on the upper and lower Tokachi River, and from one of its tributaries) in June 2004 and 2005. ?(13)C values were -27.8 to -26.9 ‰ for humic and fulvic acids. On the other hand, the ?(14)C values ranged from -247 to +26 ‰ and the average values were -170 ± 79 ‰ for humic acid and -44 ± 73 ‰ for fulvic acid. The difference was attributed to the residence time of fulvic acid in the watershed being shorter than that of humic acid. The large variation suggested that humic substances have a different pathway in each watershed environment. PMID:21515623

Nagao, Seiya; Kodama, Hiroki; Aramaki, Takafumi; Fujitake, Nobuhide; Uchida, Masao; Shibata, Yasuyuki

2011-07-01

355

The Comparison Effects of Palm Oil Fatty Acid and Stearic Acid on Dynamic Properties, Curing Characteristics and Mechanical Properties of Carbon Black Filled Epoxidized Natural Rubber Compounds  

Microsoft Academic Search

The effects of palm oil fatty acid and stearic acid on dynamic properties, curing characteristics and mechanical properties of carbon black filled epoxidized natural rubber compounds were studied. It was found that the scorch time, t2 and cure time, t90 increased with increasing both acids concentrations. For dynamic properties, the maximum elastic torque, increased with acids concentration, whereas the minimum

Hanafiismail; S. K. Kamal; S. E. Mark

2001-01-01

356

Heterogeneous reactions of gaseous hydrogen peroxide on pristine and acidic gas-processed calcium carbonate particles: Effects of relative humidity and surface coverage of coating  

NASA Astrophysics Data System (ADS)

Atmospheric aging appears to alter physical and chemical properties of mineral dust aerosol and thus its role as reactive surface in the troposphere. Yet, previous studies in the atmosphere have mainly focused on the pristine surfaces of mineral dust aerosol, and the reactivity of aged mineral dust toward atmospheric trace gases is poorly recognized. This work presents the first laboratory investigation of heterogeneous reactions of gaseous hydrogen peroxide (H2O2), an important atmospheric oxidant, on the surfaces of HNO3 and SO2-processed calcium carbonate particles as surrogates of atmospheric mineral dust aged by acidic trace gases. It is found that the processing of the calcium carbonate particles with HNO3 and SO2 has a strong impact on their reactivity toward H2O2. On HNO3-processed particles, the presence of nitrate acts to either decrease or increase H2O2 uptake, greatly depending on RH and surface coverage of nitrate. On SO2-processed particles, the presence of surface sulfite appears to enhance the intrinsic reactivity of the mineral particles due to its affinity for H2O2, and the uptake of H2O2 increases significantly relative to the pristine particles, in particular at high RH. The mechanisms for heterogeneous reactions of H2O2 with these processed particles are discussed, as well as their potential implications on tropospheric chemistry. The results of our study suggest that the reactivity of mineral dust aerosol toward H2O2 and maybe other trace gases is markedly dependent on the chemical composition and coverage of the coatings as well as ambient RH, and thus will vary considerably in different polluted air masses.

Zhao, Yue; Chen, Zhongming; Shen, Xiaoli; Huang, Dao

2013-03-01

357

Chemical and biological consequences of using carbon dioxide versus acid additions in ocean acidification experiments  

USGS Publications Warehouse

Use of different approaches for manipulating seawater chemistry during ocean acidification experiments has confounded comparison of results from various experimental studies. Some of these discrepancies have been attributed to whether addition of acid (such as hydrochloric acid, HCl) or carbon dioxide (CO2) gas has been used to adjust carbonate system parameters. Experimental simulations of carbonate system parameter scenarios for the years 1766, 2007, and 2100 were performed using the carbonate speciation program CO2SYS to demonstrate the variation in seawater chemistry that can result from use of these approaches. Results showed that carbonate system parameters were 3 percent and 8 percent lower than target values in closed-system acid additions, and 1 percent and 5 percent higher in closed-system CO2 additions for the 2007 and 2100 simulations, respectively. Open-system simulations showed that carbonate system parameters can deviate by up to 52 percent to 70 percent from target values in both acid addition and CO2 addition experiments. Results from simulations for the year 2100 were applied to empirically derived equations that relate biogenic calcification to carbonate system parameters for calcifying marine organisms including coccolithophores, corals, and foraminifera. Calculated calcification rates for coccolithophores, corals, and foraminifera differed from rates at target conditions by 0.5 percent to 2.5 percent in closed-system CO2 gas additions, from 0.8 percent to 15 percent in the closed-system acid additions, from 4.8 percent to 94 percent in open-system acid additions, and from 7 percent to 142 percent in open-system CO2 additions.

Yates, Kimberly K.; DuFore, Christopher M.; Robbins, Lisa L.

2013-01-01

358

Spectroscopic detection of the most stable carbonic acid, cis-cis H2CO3  

NASA Astrophysics Data System (ADS)

Carbonic acid had not been detected by any spectroscopic means for a long period. Recently, we have reported the detection of its second most stable conformer, cis-trans H2CO3, as the first spectroscopic detection of the isolated carbonic acid molecule. In the present work, the most stable conformer of carbonic acid, cis-cis H2CO3, in the gas phase has been successfully produced in a supersonic jet using a pulsed discharge nozzle, and pure rotational transitions of this molecule have been observed by a Fourier-transform microwave spectrometer. In addition to cis-cis H2CO3, its deuterated isotopologue, cis-cis D2CO3, has been observed, yielding the r0 structure of the cis-cis conformer. Furthermore, hyperfine constants of the deuterated cis-trans conformers were also determined. The two structures for the stable isolated carbonic acid molecule, those of the cis-cis and cis-trans conformers, are considered to provide basic information for the understanding of chemical reactions involving carbonic acid The present result is accurate enough to be used in radio astronomical observations, where the ortho/para ratio of cis-cis H2CO3 may be used as an important probe of interstellar chemistry.

Mori, Tetsuya; Suma, Kohsuke; Sumiyoshi, Yoshihiro; Endo, Yasuki

2011-01-01

359

Carbon Mineralization in Acidic, Xeric Forest Soils: Induction of New Activities †  

PubMed Central

Carbon mineralization was examined in Lakehurst and Atsion sands collected from the New Jersey Pinelands and in Pahokee muck from the Everglades Agricultural Area. Objectives were (i) to estimate the carbon mineralization capacities of acidic, xeric Pinelands soils in the absence of exogenously supplied carbon substrate (nonamended carbon mineralization rate) and to compare these activities with those of agriculturally developed pahokee muck, and (ii) to measure the capacity for increased carbon mineralization in the soils after carbon amendment. In most cases, nonamended carbon mineralization rates were greater in samples of the acid- and moisture-stressed Pinelands soils than in Pahokee muck collected from a fallow (bare) field. Carbon amendment resulted in augmented catabolic activity in Pahokee muck samples, suggesting that the microbial community was carbon limited in this soil. With many of the substrates, no stimulation of the catabolic rate was detected after amendment of Pinelands soils. This was documented by the observation that amendment of Pahokee muck with an amino acid mixture, glucose, or acetate resulted in a 3.0-, 3.9-, or 10.5-fold stimulation of catabolic activity, respectively, for the added substrate. In contrast, amendment of the Pinelands soils resulted in increased amino acid and acetate catabolic rates in Lakehurst sand and increased acetate metabolism only in Atsion sand. Other activities were unchanged. The increased glucose respiration rates resulted from stimulation of existing microbial activity rather than from microbial proliferation since no change in the microbial growth rate, as estimated by the rate of incorporation of 14C-labeled acetate into cell membranes, occurred after glucose amendment of the soils. A stimulation of microbial growth rate was recorded with glucose-amended Lakehurst sand collected from the B horizon.

Tate, Robert L.

1985-01-01

360

The use of acetic acid as a source of carbon by cultured Chondrus crispus (Gigartinales, Rhodophyta) stackhouse  

Microsoft Academic Search

When growing seaweeds in tanks, pH and carbon source supply have to be controlled in order to maximize photosynthesis. pH can be controlled either by adding various inorganic acids which requires the extra addition of carbon, or by combining pH control and carbon source with for instance CO2 or an organic acid such as acetic acid (CH3COOH). We have found

Mireille A. Amat; Jean-Paul Braud

1993-01-01

361

Black carbon and its correlation with trace gases at a rural site in Beijing: Top-down constraints from ambient measurements on bottom-up emissions  

NASA Astrophysics Data System (ADS)

The mass concentrations of black carbon (BC) were measured continuously at Miyun, a rural site near Beijing, concurrently with some trace gases (CO, CO2, NOy, SO2) during the nonheating seasons of 2010 (April to October). The average concentration of BC was 2.26 ± 2.33 ?g m-3. About 70%-100% of the air masses arriving at the site from June to September were from the source region of Beijing and the North China Plain (NCP), while in the spring, 40% were of continental background origin. BC had moderate to strong positive correlations with CO (R2 = 0.51), NOy (R2 = 0.58), and CO2 (nonsummer, R2 = 0.54), but not with SO2 (R2 < 0.1). The observed ?BC/?CO ratio was 0.0050 ± 0.0001 ?g m-3/ppbv for the regional air masses (excluding the influence of biomass burning). This ratio increased by 68% to 0.0084 ± 0.0004 ?g m-3/ppbv after excluding the influence of wet deposition. Accounting further for the impact of atmospheric processes on the observation, we derived an average top-down BC/CO emission ratio of 0.0095 ± 0.002 ?g m-3/ppbv for the source region of Beijing and NCP that is 18%-21% lower than the average emission ratio from the bottom-up inventory of Zhang et al. (2009), whereas the difference is substantially lower than the uncertainty of emissions for either species. The difference between the mean bottom-up and top-down emission ratios is most likely to be attributed to the residential sector, which needs to have a lower share in the total emissions of BC or a much lower BC/CO emission ratio. The industry and transportation sectors are found to be dominant sources of BC from Beijing and the NCP rather than from the residential sector as suggested by the bottom-up inventory.

Wang, Yuxuan; Wang, Xuan; Kondo, Yutaka; Kajino, Mizuo; Munger, J. William; Hao, Jiming

2011-12-01

362

Biosynthesis of L-Ascorbic Acid and Conversion of Carbons 1 and 2 of L-Ascorbic Acid to Oxalic Acid Occurs within Individual Calcium Oxalate Crystal Idioblasts  

Microsoft Academic Search

the pattern OxA . AsA (erythorbic acid) . l-galactose . d-mannose. Our results demonstrate that P. stratiotes crystal idioblasts synthesize the OxA used for crystal formation, the OxA is derived from the number 1 and 2 carbons of AsA, and the proposed pathway of ascorbic acid synthesis via d-mannose and l-galactose is operational in individual P. stratiotes crystal idioblasts. These

Todd A. Kostman; Nathan M. Tarlyn; Frank A. Loewus; Vincent R. Franceschi

2001-01-01

363

pH-Uncontrolled lactic acid fermentation with activated carbon as an adsorbent.  

PubMed

In this paper, we presented a novel process involving activated carbon (AC) as an adsorbent for lactic acid fermentation, separation and oligomerization. It was found that pH has a significant effect on the adsorption of lactic acid on AC. The use of AC for in situ removal of lactic acid successfully decreased the inhibitory effect of lactic acid, resulting in significant increases in both productivity and yield. Acetone was used to desorb lactic acid and it was confirmed that the acetone treatment did not decrease the optical purity of the lactic acid, i.e., the optical purity was as high as 99.5% after desorption. Due to the presence of little materials influencing lactic acid oligomerization, oligomers with an optical purity of above 96% and a weight-average molecular weight (M(w)) of 2400 were obtained in the oligomerization process. PMID:22113026

Gao, Min-Tian; Shimamura, Takashi; Ishida, Nobuhiro; Takahashi, Haruo

2011-05-01

364

Carbon dioxide-sustained adsorption of lactic acid at pH > pK{sub a} of the acid  

SciTech Connect

Experimental data are presented for batch and fixed-bed adsorption of lactic acid from aqueous sodium lactate solutions onto the tertiary amine sorbents, Dowex MWA-1 and Amberlite IRA-35, in the presence of carbon dioxide. The effects of carbon dioxide pressure and sodium lactate concentration on lactate uptake capacity were measured. A simple complexation model, which includes chemical-equilibria and mass- and charge-balance equations, was developed to describe the system. There are no fitted parameters in the model. The model predictions compare well with batch adsorption data.

Husson, S.M.; King, C.J. [Lawrence Berkeley National Lab., CA (United States)] [Lawrence Berkeley National Lab., CA (United States)

1999-04-01

365

Synthesis of carbon/EMD composite from carbon-suspended sulfuric acid and manganese sulfate bath  

NASA Astrophysics Data System (ADS)

A study has been made of the electrodeposition of MnO2 on a titanium anode from a carbon or carbon/MnO2 composite suspended in a H2SO4-MnSO4 bath. Electrolytic manganese dioxide (EMD) containing acetylene black or vapor-grown carbon fiber shows excellent alkaline battery performance and good grindability. Nevertheless, passivation of the titanium anode sometimes occurs during electrolysis at a current density of 1 A dm(exp -2). This problem is successfully resolved without loss of battery performance, by using carbon/ delta-MnO2 as suspension particles. Apart from producing EMDs with good grindability and excellent battery performance, this bath has several other advantages, namely: easy maintenance of the dispersion, good reproducibility, low anode potential during electrolysis, and higher carbon content. It is proposed that a close relationship exists between battery performance and the surface characteristics of EMDs such as BET surface area and pore size.

Piao, Gen-Pei; Yoshio, Masaki; Noguchi, Hideyuki; Kozawa, Akiya

1994-10-01

366

Carbon isotope composition of low molecular weight hydrocarbons and monocarboxylic acids from Murchison meteorite  

NASA Technical Reports Server (NTRS)

Carbon isotopic compositions have been measured for individual hydrocarbons and monocarboxylic acids from the Murchison meteorite, a C2 carbonaceous chondrite which fell in Australia in 1969. With few exceptions, notably benzene, the volatile products are substantially isotopically heavier than their terrestrial counterparts, signifying their extraterrestrial origin. For both classes of compounds, the ratio of C-13 to C-12 decreases with increasing carbon number in a roughly parallel manner, and each carboxylic acid exhibits a higher isotopic ratio than the hydrocarbon containing the same number of carbon atoms. These trends are consistent with the kinetically controlled synthesis of higher homologues from lower ones. The results suggest the possibility that the production mechanisms for hydrocarbons and carboxylic acids may be similar, and impose constraints on the identity of the reactant species.

Yuen, G.; Blair, N.; Des Marais, D. J.; Chang, S.

1984-01-01

367

SORPTION OF MERCURY SPECIES BY ACTIVATED CARBONS AND CALCIUM-BASES SORBENTS: EFFECT OF TEMPERATURE, MERCURY CONCENTRATION AND ACID GASES  

EPA Science Inventory

Bench-scale studies of mercury/sorbent reactions were conducted to understand mechanistic limitations of field-scale attempts to reduce emissions of mercury from combustion processes. The effects of temperature (60 - 140 degrees C), sulfur dioxide (SO2, 1000 ppm ), hydrogen chlor...

368

Wine wastes as carbon source for biological treatment of acid mine drainage  

Microsoft Academic Search

Possible use of wine wastes containing ethanol as carbon and energy source for sulphate-reducing bacteria (SRB) growth and activity in the treatment of acid mine drainage (AMD) is studied for the first time. The experiments were performed using anaerobic down-flow packed bed reactors in semi-continuous systems. The performance of two bioreactors fed with wine wastes or ethanol as carbon sources

M. C. Costa; E. S. Santos; R. J. Barros; C. Pires; M. Martins

2009-01-01

369

The inhibition of carbon steel corrosion in hydrochloric and sulfuric acid media using some benzimidazole derivatives  

Microsoft Academic Search

The corrosion inhibition of carbon steel in HCl and H2SO4 solutions in the presence of some benzimidazole derivatives such as benzimidazole (BI), 2-methylbenzimidazole (2-CH3-BI) and 2-mercaptobenzimidazole (2-SH-BI) was investigated using potentiodynamic polarization technique. Results obtained showed that the benzimidazole derivatives retard both the cathodic and anodic reactions in both acidic media, by virtue of adsorption on the carbon steel surface.

J. Aljourani; M. A. Golozar; K. Raeissi

2010-01-01

370

Examining the Microbial Degradation of Naphthenic Acids Using Stable Isotope Analysis of Carbon and Nitrogen  

Microsoft Academic Search

Naphthenic acids (NAs) are a complex group of naturally occurring oil sands constituents that constitute a significant portion\\u000a of the dissolved organic carbon (DOC) pool available for microbial degradation in the process-related waste water associated\\u000a with oil sands mine sites. One approach to understanding the biological fate of oil sands process-derived carbon and nitrogen\\u000a in aquatic reclamation of the mine

Patricia P. Videla; Andrea J. Farwell; Barbara J. Butler; D. George Dixon

2009-01-01

371

Utilization of carbon and nitrogen sources and acid\\/alkali production by cowpea rhizobia  

Microsoft Academic Search

Summary Sixteen slow-growing strains of rhizobia (15 cowpea rhizobia and oneR. japonicum) were examined to determine the effects of carbon and nitrogen sources on acid\\/alkali production in culture media. We found that the pH changes of the medium were more influenced by nitrogen sources than carbon sources (with the exception of ribose). When ammonium sulphate was used as a nitrogen

M. H. Ahmad; Eustace Smith

1985-01-01

372

Roles of oleic acid during micropore dispersing preparation of nano-calcium carbonate particles  

NASA Astrophysics Data System (ADS)

In the present work, nano-calcium carbonate powder was prepared by micropore dispersion method with assistance of oleic acid as surfactant. CO 2 gas was dispersed into the Ca(OH) 2/H 2O slurry via a glass micropore-plate with the diameter of micropore about 20 ?m. To investigate the effect of oleic acid on the size of CaCO 3 particles, different amount of oleic acid was added in Ca(OH) 2/H 2O slurry at 5 °C and 25 °C, respectively. XRD patterns show that cubic calcite is the only crystalline phase in all cases. ZPA data and TEM photo indicate that the average particle size synthesized at 5 °C without oleic acid is of about 40 nm, slightly smaller than that of prepared at 25 °C, and that the dispersity of sample prepared at 5 °C is better than that of 25 °C. When oleic acid is added in both temperatures, the average particle size decreases a little. FT-IR spectra demonstrate that oleic acid interacts with Ca 2+ and carbon-carbon double bond existed on the surface of particle. Consequently, two opposite roles of oleic acid during the process of preparation of nano-CaCO 3 were proposed, namely preventing nanoparticles from growing during reaction and making nanoparticles reunite to a certain extent after reaction.

Jiang, Jiuxin; Liu, Jie; Liu, Chang; Zhang, Gaowen; Gong, Xinghou; Liu, Jianing

2011-06-01

373

One-Pot synthesis of phosphorylated mesoporous carbon heterogeneous catalysts with tailored surface acidity  

SciTech Connect

Soft-templated phosphorylated mesoporous carbons with homogeneous distributions of phosphate groups were prepared by a 'one-pot' synthesis method using mixtures of phosphoric acid with hydrochloric, or nitric acids in the presence of Pluronic F127 triblock copolymer. Adjusting the various ratios of phosphoric acid used in these mixtures resulted in carbons with distinct adsorption, structural and surface acidity properties. The pore size distributions (PSDs) from nitrogen adsorption at -196 C showed that mesoporous carbons exhibit specific surface areas as high as 551 m{sup 2}/g and mesopores as large as 13 nm. Both structural ordering of the mesopores and the final phosphate contents were strongly dependent on the ratios of H{sub 3}PO{sub 4} in the synthesis gels, as shown by transmission electron microscopy (TEM), X-ray photoelectron (XPS) and energy dispersive X-ray spectroscopy (EDS). The number of surface acid sites determined from temperature programmed desorption of ammonia (NH{sub 3}-TPD) were in the range of 0.3-1.5 mmol/g while the active surface areas are estimated to comprise 5-54% of the total surface areas. Finally, the conversion temperatures for the isopropanol dehydration were lowered by as much as 100 C by transitioning from the least acidic to the most acidic catalysts surface.

Fulvio, Pasquale F [ORNL; Mahurin, Shannon Mark [ORNL; Mayes, Richard T [ORNL; Bauer, Christopher [ORNL; Wang, Xiqing [ORNL; Veith, Gabriel M [ORNL; Dai, Sheng [ORNL

2012-01-01

374

Recovery of calcium carbonate from steelmaking slag and utilization for acid mine drainage pre-treatment.  

PubMed

The conversion of steelmaking slag (a waste product of the steelmaking process) to calcium carbonate (CaCO(3)) was tested using hydrochloric acid, ammonium hydroxide and carbon dioxide via a pH-swing process. Batch reactors were used to assess the technical feasibility of calcium carbonate recovery and its use for pre-treatment of acid mine drainage (AMD) from coal mines. The effects of key process parameters, such as the amount of acid (HCl/calcium molar ratio), the pH and the CO(2) flow rate were considered. It was observed that calcium extraction from steelmaking slag significantly increased with an increase in the amount of hydrochloric acid. The CO(2) flow rate also had a positive effect on the carbonation reaction rate but did not affect the morphology of the calcium carbonate produced for values less than 2 L/min. The CaCO(3) recovered from the bench scale batch reactor demonstrated effective neutralization ability during AMD pre-treatment compared with the commercial laboratory grade CaCO(3). PMID:22643421

Mulopo, J; Mashego, M; Zvimba, J N

2012-01-01

375

Acetaldehyde stimulation of net gluconeogenic carbon movement from applied malic acid in tomato fruit pericarp tissue  

SciTech Connect

Applied acetaldehyde is known to lead to sugar accumulation in fruit including tomatoes (Lycopersicon esculentum) presumably due to stimulation of gluconeogenesis. This conjecture was examined using tomato fruit pericarp discs as a test system and applied l-(U-{sup 14}C)malic acid as the source for gluconeogenic carbon mobilization. Results indicate that malic and perhaps other organic acids are carbon sources for gluconeogenesis occurring normally in ripening tomatoes. The process is stimulated by acetaldehyde apparently by attenuating the fructose-2,6-biphosphate levels. The mode of the acetaldehyde regulation of fructose-2,6-biphosphate metabolism awaits clarification.

Halinska, A.; Frenkel, C. (Rutgers, The State Univ. of New Jersey, New Brunswick (United States))

1991-03-01

376

Revised black carbon assessment using benzene polycarboxylic acids  

Microsoft Academic Search

Black carbon (BC), the ubiquitous stable product of incomplete combustion, is believed to be a potential sink for atmospheric CO2 and therefore a contributor to the Earth’s radiative heat balance. Nevertheless, analytical procedures to measure BC are inconsistent, giving a non-systematic variation by factors of 14–571 for estimates of its content in soil. We hypothesized that the HCl used to

S. Brodowski; A. Rodionov; L. Haumaier; B. Glaser; W. Amelung

2005-01-01

377

Water-soluble organic carbon, dicarboxylic acids, ketoacids, and alpha-dicarbonyls in the tropical Indian aerosols  

Microsoft Academic Search

Tropical aerosol (PM10) samples (n = 49) collected from southeast coast of India were studied for water-soluble dicarboxylic acids (C2-C12), ketocarboxylic acids (C2-C9), and alpha-dicarbonyls (glyoxal and methylglyoxal), together with analyses of total carbon (TC) and water-soluble organic carbon (WSOC). Their distributions were characterized by a predominance of oxalic acid followed by terephthalic (t-Ph), malonic, and succinic acids. Total concentrations

Chandra Mouli Pavuluri; Kimitaka Kawamura; T. Swaminathan

2010-01-01

378

Stable carbon isotope measurements of atmospheric organic acids in Los Angeles, California  

SciTech Connect

Atmospheric organic acids are ubiquitous constituents of urban smog and haze and are also present in the atmospheres of rural and largely uninhabited areas (e.g., the Amazon Rain Forest Basin). The authors report here source characterization of atmospheric organic acids in Los Angeles by measurements of their stable carbon isotopic ratios, e.g., {sup 13}C/{sup 12}C({delta}{sup 13}C). The study was performed by separating formic and acetic acids using ion chromatography exclusion (ICE) and isolating milligram quantities of individual organic acids from atmospheric rain samples. Authentic reference samples of formic and acetic acids were used to determine that only a negligible isotope fractionation of {delta}{sup 13}C value occurs after the ICE separation. During 1991-1992, rainwaters were collected in Los Angeles to isolate formic and acetic acids for the isotope measurements. Results presented in this paper demonstrate a significant isotopic difference between the mean {delta}{sup 13}C value for acetic acid ({minus}20.5{per_thousand}) and formic acid ({minus}30.1{per_thousand}). The authors conclude from these results that the formic acid is derived from mixing of formic acid from direct emissions with the acid formed by secondary oxidation processes in the atmosphere, most probably from aldehydes, whereas acetic acid originates only from direct source emissions. 26 refs., 1 fig., 2 tabs.

Sakugawa, H. [Hiroshima Univ. (Japan)] [Hiroshima Univ. (Japan); Kaplan, I.R. [Univ. of California, Los Angeles, CA (United States)] [Univ. of California, Los Angeles, CA (United States)

1995-06-15

379

Modification of carbon nanotube electrodes with 1-pyrenebutanoic acid, succinimidyl ester for enhanced bioelectrocatalysis.  

PubMed

Conductive materials functionalized with redox enzymes provide bioelectronic architectures with application to biological fuel cells and biosensors. Effective electron transfer between the enzyme (biocatalyst) and the conductive materials is imperative for function. Various nanostructured carbon materials are common electrode choices for these applications as both the materials' inherent conductivity and physical integrity aids optimal performance. The following chapter presents a method for the use of carbon nanotube buckypaper as a conductive architecture suitable for biocatalyst functionalization. In order to securely attach the biocatalyst to the carbon nanotube surface, the conductive buckypaper is modified with the heterobifunctional cross-linker, 1-pyrenebutanoic acid, succinimidyl ester. The technique effectively tethers the enzyme to the carbon nanotube which enhances bioelectrocatalysis, preserves the conductive nature of the carbon surface, and facilities direct electron transfer between the catalyst and material interface. The approach is demonstrated using phenol oxidase (laccase) and pyrroloquinoline quinone-dependent glucose dehydrogenase PQQ-GDH, as representative biocatalysts. PMID:23934807

Strack, Guinevere; Nichols, Robert; Atanassov, Plamen; Luckarift, Heather R; Johnson, Glenn R

2013-01-01

380

Quantification and mass isotopomer profiling of ?-keto acids in central carbon metabolism.  

PubMed

Mass spectrometry has been established as a powerful and versatile technique for studying cellular metabolism. Applications range from profiling of metabolites to accurate quantification and tracing of stable isotopes through the biochemical reaction network. Despite broad coverage of central carbon metabolism, most methods fail to provide accurate assessments of the ?-keto acids oxaloacetic acid, pyruvate, and glyoxylate because these compounds are highly reactive and degraded during sample processing and mass spectrometric measurement. We present a derivatization procedure to chemically stabilize these compounds readily during quenching of cellular metabolism. Stable derivatives were analyzed by ultrahigh pressure liquid chromatography coupled tandem mass spectrometry to accurately quantify the abundance of ?-keto acids in biological matrices. Eventually, we demonstrated that the developed protocol is suited to measure mass isotopomers of these ?-keto acids in tracer studies with stable isotopes. In conclusion, the here described method fills one of the last technical gaps for metabolomics investigations of central carbon metabolism. PMID:24533614

Zimmermann, Michael; Sauer, Uwe; Zamboni, Nicola

2014-03-18

381

Metabolically engineered Escherichia coli for biotechnological production of four-carbon 1,4-dicarboxylic acids  

Microsoft Academic Search

Confronted with inescapable exhaustion of the earth’s fossil energy resources, the bio-based process to produce industrial\\u000a chemicals is receiving significant interest. Biotechnological production of four-carbon 1,4-dicarboxylic acids (C4 diacids)\\u000a from renewable plant biomass is a promising and attractive alternative to conventional chemistry routes. Although the C4 diacids\\u000a pathway is well characterized and microorganisms able to convert biomass to these acids

Yujin Cao; Yugang Cao; Xiangzhi Lin

2011-01-01

382

Adsorption of benzoic acid onto high specific area activated carbon cloth  

Microsoft Academic Search

The adsorption of benzoic acid from aqueous solution onto high area carbon cloth at different pH values has been studied. Over a period of 125 min the adsorption process was found to follow a first-order kinetics and the rate constants were determined for the adsorption of benzoic acid at pH 2.0, 3.7, 5.3, 9.1, and 11.0. The extents of adsorption

Erol Ayranci; Numan Hoda; Edip Bayram

2005-01-01

383

Miscibility and Properties of Acid-Treated Multi-Walled Carbon Nanotubes\\/Polyurethane Nanocomposites  

Microsoft Academic Search

Nanocomposites based on polyurethane and acid-treatment multi-walled carbon nanotubes (A-MWNTs) are prepared by solution blending. The surface of the MWNTs was modified by acid treatment to incorporated functional groups. The modified MWNTs exhibited improved dispersion in organic solvents and miscibility with the PU matrix. The derivatives of MWNTs were characterized by Fourier transform infrared (FT-IR) spectroscopy, Transmission electron microscopy (TEM)

Chi-Hung Lee; Jia-Yi Liu; Shen-Liang Chen; Yen-Zen Wang

2007-01-01

384

Inhibition of carbon steel corrosion by azathione derivatives in organic acid solutions  

Microsoft Academic Search

Purpose – The purpose of this paper is to investigate the inhibitive effect of azathiones, namely cyclopentyl-tetrahydro-azathione, cyclohexyl-tetrahydro-azathione and isobutyl-methyl-tetrahydro-azathione on the corrosion of carbon steel in formic and acetic acid solution. The effect of inhibitor concentration, immersion time, acid concentration, and solution temperature on the inhibition efficiencies of the selected azathiones were studied systematically. Design\\/methodology\\/approach – The synthesis of

Sadaf Khan; M. Z. A. Rafiquee; Nidhi Saxena; M. A. Quraishi

2009-01-01

385

Sources to formic acid studied by carbon isotopic analysis and air mass characterization  

Microsoft Academic Search

The carbon isotopic composition of formic acid samples from a rural and a semi-remote area in Denmark has been investigated by collection of 5–6 day integrated samples during winter and spring. The results show that 80–100% of formic acid stems from biogenic VOC emitted from terrestrial sources. Even during winter there is a dominating biogenic contribution, which is surprising since

M. Glasius; S. Wessel; C. S. Christensen; J. K. Jacobsen; H. E. Jørgensen; K. C. Klitgaard; L. Petersen; J. K. Rasmussen; T. Stroyer Hansen; C. Lohse; E. Boaretto; J. Heinemeier

2000-01-01

386

Synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotubes and carbon fiber for improved electro-activated polymeric shape-memory nanocomposite  

NASA Astrophysics Data System (ADS)

The present work studies the synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotube (CNT) and carbon fiber on the electrical property and electro-activated recovery behavior of shape memory polymer (SMP) nanocomposites. The combination of CNT and carbon fiber results in improved electrical conductivity in the SMP nanocomposites. Carboxylic acid-functionalized CNTs are grafted onto the carbon fibers and then self-assembled by deposition to significantly enhance the reliability of the bonding between carbon fiber and SMP via van der Waals and covalent crosslink. Furthermore, the self-assembled carboxylic acid-functionalized CNTs and carbon fibers enable the SMP nanocomposites for Joule heating triggered shape recovery.

Lu, Haibao; Min Huang, Wei

2013-06-01

387

Simple quantification of surface carboxylic acids on chemically oxidized multi-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The surface of multi-walled carbon nanotube (MWCNT) was chemically oxidized using nitric acid and sulfuric-nitric acid mixtures. Thermogravimetric analysis, transmission electron microscopy and infrared spectroscopy revealed that the use of acid mixtures led to higher degree of oxidation. More quantitative identification of surface carboxylic acids was carried out using X-ray photoelectron spectroscopy (XPS) and acid-base titration. However, these techniques are costly and require very long analysis times to promptly respond to the extent of the reaction. We propose a much simpler method using pH measurements and pre-determined pKa value in order to estimate the concentration of carboxylic acids on the oxidized MWCNT surfaces. The results from this technique were consistent with those obtained from XPS and titration, and it is expected that this simple quantification method can provide a cheap and fast way to monitor and control the oxidation reaction of MWCNT.

Gong, Hyejin; Kim, Seong-Taek; Lee, Jong Doo; Yim, Sanggyu

2013-02-01

388

Efficient optical resolution of amino acid by alanine racemaze chiral analogue supported on mesoporous carbon  

NASA Astrophysics Data System (ADS)

Optically pure D-amino acids are industrially important chiral building blocks for the synthesis of pharmaceuticals, food ingredients, and drug intermediates. Chemoenzymatic dynamic kinetic-resolution processes have recently been developed for deracemization of amino acids. S-ARCA would be a good candidate for the selective adsorption of D amino acid through the imine formation reaction. The organic phase containing S-ARCA adsorbent, TPPC or Ionic Liquid (as a phase transfer catalyst) in MC were coated on the surfaces of mesoporous carbon C-SBA-15(CMK). The aqueous solution of racemic D/L-amino acid and NaOH were added to the carbon support coated with ARCA. The D/L ratios on ARCA and in solution were determined with increasing reaction time. S-ARCA has a unique property for the selective adsorption of D- amino acid (up to 90% selcetivity) in the racemic mixture. The fixed bed reactor containing ARCA/carbon support was also adopted successfully for the selective separation of amino acid.

Jang, D.; Kim, K.; Park, D.; Kim, G.

2012-09-01

389

Neutralizing Carbonic Acid in Deep Carbonate Strata below the North Atlantic  

SciTech Connect

Our research is aimed at investigating several technical issues associated with carbon dioxide sequestration in calcium carbonate sediments below the sea floor through laboratory experiments and chemical transport modeling. Our goal is to evaluate the basic feasibility of this approach, including an assessment of optimal depths, sediment types, and other issues related to site selection. Through laboratory and modeling efforts, we are studying the flow of liquid carbon dioxide and carbon dioxide-water mixtures through calcium carbonate sediments to better understand the geomechanical and structural stability of the sediments during and after injection. Our modeling efforts in the first year show that the idea is feasible, but requires more sophisticated analysis of fluid flow at high pressure in deep sea sediments. In addition, we are investigating the kinetics of calcium carbonate dissolution in the presence of CO{sub 2}-water fluids, which is a critical feature of the system as it allows for increased permeability during injection. Our experimental results from the first year of work have shown that the kinetics are likely to be fast enough to create dissolution which will affect permeability. However, additional experiments are needed at high pressures, which will be a focus for years 2 and 3. We are also investigating the possibility of carbon dioxide hydrate formation in the pore fluid, which might complicate the injection procedure by reducing sediment permeability but might also provide an upper seal in the sediment-pore fluid system, preventing release of CO{sub 2} into the deep ocean, particularly if depth and temperature at the injection point rule out immediate hydrate formation. Finally, we are in the beginning stages of an economic analysis to estimate costs of drilling and gas injection, site monitoring as well as the availability of potential disposal sites with particular emphasis on those sites that are within the 200-mile economic zone of the United States.

Daniel P. Schrag

2005-12-01

390

Process for eliminating diluted sulfur oxides in combustion exhaust gases  

Microsoft Academic Search

A process is disclosed for eliminating sulfur oxides from combustion exhaust gases, comprising the steps of dividing the combustion exhaust gases into a first stream and a second stream, and passing the first stream through a first activated carbon bed which was previously washed with water, thereby drying the activated carbon, cooling the first stream, and removing a substantial portion

S. Hori; T. Inoue; S. Yamamoto; K. Tatara; M. Kitagawa; M. Watanabe; Y. Okada; N. Negishi

1978-01-01

391

NON-CO2 GREENHOUSE GASES IN THE ATMOSPHERE  

Microsoft Academic Search

Abstract Although global warming is generally linked to increasing levels of carbon dioxide, there are many other gases produced from industrial, agricultural, and energy-generating sources that can also cause the Earth's temperature to rise. Individually these gases are not likely to make a significant contribution, but, taken together, it is believed that they can rival the effects of carbon dioxide.

M. A. K. Khalil

1999-01-01

392

Coastal ocean CO2-carbonic acid-carbonate sediment system of the Anthropocene  

NASA Astrophysics Data System (ADS)

There is little doubt that human activities such as burning of fossil fuels and land use practices have changed and will continue to change the cycling of carbon in the global coastal ocean. In the present study, two biogeochemical box models were used to investigate the consequences of increasing atmospheric CO2 and subsequent ocean acidification and increasing riverine transport of organic matter and nutrients arising from human activities on land on the global coastal ocean between the years 1700 and 2300. Numerical simulations show that the net flux of CO2 between coastal ocean surface water and the atmosphere is likely to change during this time from net evasion to net invasion owing to increasing atmospheric CO2, increasing net ecosystem production arising from increasing nutrient loading to this region, and decreasing net ecosystem calcification due to lower carbonate ion concentration and subsequent lower surface water saturation state with respect to carbonate minerals. Model calculations show that surface water saturation state with respect to calcite will decrease 73% by the year 2300 under a business-as-usual scenario, which in concert with increasing temperature will cause overall biogenic calcification rate to decrease by 90%. Dissolution of carbonate minerals increased by 267% throughout the model simulation. This increase was in part due to increased invasion of atmospheric CO2, but mainly due to greater deposition and remineralization of land-derived and in situ produced organic matter in the sediments, producing CO2 that caused pore water pH and carbonate saturation state to decrease. This decrease, in turn, drove selective dissolution of metastable carbonate minerals. As a consequence, the relative carbonate composition of the sediments changed in favor of carbonate phases with lower solubility than that of an average 15 mol% magnesian calcite phase. Model projected changes in surface water carbonate saturation state agree well with observations from the Hawaiian Ocean Time series and the calculated air-sea CO2 exchange agrees well with a recent independent estimate of this flux derived from measurements from diverse coastal ecosystems scaled up to the global coastal ocean area.

Andersson, Andreas J.; MacKenzie, Fred T.; Lerman, Abraham

2006-03-01

393

Process for separating, especially in multiple stages, acid components such as CO/sub 2/, HCN and specifically H/sub 2/S, from gases, especially from coke oven gases, by means of ammonia recirculation scrubbing  

SciTech Connect

A process of separating in multiple stages acid components in coke oven gas such as CO/sub 2/, HCN and particularly H/sub 2/S by ammonia scrubbing wherein the ammonia used in scrubbing is deacidified to remove the acid components and is recirculated to the scrubbing process at least in part as substantially pure liquid ammonia.

Bauer, H.K.; Otte, E.A.W.

1984-10-16

394

Microbial mediated formation of Fe-carbonate minerals under extreme acidic conditions  

NASA Astrophysics Data System (ADS)

Discovery of Fe-carbonate precipitation in Rio Tinto, a shallow river with very acidic waters, situated in Huelva, South-western Spain, adds a new dimension to our understanding of carbonate formation. Sediment samples from this low-pH system indicate that carbonates are formed in physico-chemical conditions ranging from acid to neutral pH. Evidence for microbial mediation is observed in secondary electron images (Fig. 1), which reveal rod-shaped bacteria embedded in the surface of siderite nanocrystals. The formation of carbonates in Rio Tinto is related to the microbial reduction of ferric iron coupled to the oxidation of organic compounds. Herein, we demonstrate for the first time, that Acidiphilium sp. PM, an iron-reducing bacterium isolated from Rio Tinto, mediates the precipitation of siderite (FeCO3) under acidic conditions and at a low temperature (30°C). We describe nucleation of siderite on nanoglobules in intimate association with the bacteria cell surface. This study has major implications for understanding carbonate formation on the ancient Earth or extraterrestrial planets.

Sánchez-Román, Mónica; Fernández-Remolar, David; Amils, Ricardo; Sánchez-Navas, Antonio; Schmid, Thomas; Martin-Uriz, Patxi San; Rodríguez, Nuria; McKenzie, Judith A.; Vasconcelos, Crisogono

2014-04-01

395

Microbial mediated formation of Fe-carbonate minerals under extreme acidic conditions  

PubMed Central

Discovery of Fe-carbonate precipitation in Rio Tinto, a shallow river with very acidic waters, situated in Huelva, South-western Spain, adds a new dimension to our understanding of carbonate formation. Sediment samples from this low-pH system indicate that carbonates are formed in physico-chemical conditions ranging from acid to neutral pH. Evidence for microbial mediation is observed in secondary electron images (Fig. 1), which reveal rod-shaped bacteria embedded in the surface of siderite nanocrystals. The formation of carbonates in Rio Tinto is related to the microbial reduction of ferric iron coupled to the oxidation of organic compounds. Herein, we demonstrate for the first time, that Acidiphilium sp. PM, an iron-reducing bacterium isolated from Rio Tinto, mediates the precipitation of siderite (FeCO3) under acidic conditions and at a low temperature (30°C). We describe nucleation of siderite on nanoglobules in intimate association with the bacteria cell surface. This study has major implications for understanding carbonate formation on the ancient Earth or extraterrestrial planets.

Sanchez-Roman, Monica; Fernandez-Remolar, David; Amils, Ricardo; Sanchez-Navas, Antonio; Schmid, Thomas; Martin-Uriz, Patxi San; Rodriguez, Nuria; McKenzie, Judith A.; Vasconcelos, Crisogono

2014-01-01

396

The influence of type and concentration of the carbon source on production of citric acid by Aspergillus niger  

Microsoft Academic Search

The influence of various carbon sources and their concentration on the production of citrate by Aspergillus niger has been investigated. The sugars maltose, sucrose, glucose, mannose and fructose (in the given order) were carbon sources giving high yields of citric acid. Optimal yields were observed at sugar concentrations of 10% (w\\/v), with the exception of glucose (7.5%). No citric acid

Ding-Bang Xu; Cynthia P. Madrid; Max Rfihr; Christian P. Kubicek

1989-01-01

397

Acid rain damage to carbonate stone: a quantitative assessment based on the aqueous geochemistry of rainfall runoff from stone  

USGS Publications Warehouse

An onsite experimental procedure was used to identify and quantify acid rain damage to carbonate stone, based on the change in rain runoff chemical composition. Onsite data obtained during the summer and fall of 1984 at three locations in the northeastern United States indicate that carbonate stone surface recession is related to acid deposition. -from Author

Reddy, M. M.

1988-01-01

398

Linking dynamics of soil microbial phospholipid fatty acids to carbon mineralization in a 13C natural abundance experiment: Impact of heavy metals and acid rain  

Microsoft Academic Search

A 13C natural abundance experiment including GC-c-IRMS analysis of phospholipid fatty acids (PLFAs) was conducted to assess the temporal dynamics of the soil microbial community and carbon incorporation during the mineralization of plant residues under the impact of heavy metals and acid rain. Maize straw was incorporated into (i) control soil, (ii) soil irrigated with acid rain, (iii) soil amended

Michael Stemmer; Andrea Watzinger; Karl Blochberger; Georg Haberhauer; Martin H. Gerzabek

2007-01-01

399

Electrooxidation of ascorbic acid catalyzed on cobalt hydroxide-modified glassy carbon electrode  

Microsoft Academic Search

The electrochemical behavior of ascorbic acid on a cobalt hydroxide modified glassy carbon (CHM-GC) electrode in alkaline solution was investi- gated. The process of the involved oxidation and its kinetics were established using the cyclic voltammetry, chronoamperometry techniques, as well as by steady state polarization measurements. The results revealed that cobalt hyd- roxide promotes the rate of oxidation by increasing

Ghasem Karim-Nezhad; Mohammad Hasanzadeh; Lotfali Saghatforoush; Nasrin Shadjou; Balal Khalilzadeh; Sohrab Ershad

2009-01-01

400

Improved Norway spruce somatic embryo development through the use of abscisic acid combined with activated carbon  

Microsoft Academic Search

The combination of abscisic acid (ABA) and activated carbon increased Norway spruce (Picea abies L., Karst.) cotyledonary somatic embryo yields, increased the number of genotypes forming cotyledonary embryos, caused embryos to form that exhibited improved maturation characteristics, and reduced embryo production costs. Somatic embryos increased in size, showed larger apical regions, became more zygotic-like in shape, and showed higher percentages

G. S. Pullman; P. K. Gupta; R. Timmis; C. Carpenter; M. Kreitinger; E. Welty

2005-01-01

401

Pervaporation of acetic acid\\/water mixtures through carbon molecular sieve-filled PDMS membranes  

Microsoft Academic Search

The pervaporation process for acetic\\/water has been investigated with carbon molecular sieve (CMS)-filled polydimethylsiloxane (PDMS) membranes. The effects of feed temperature, feed acetic acid concentration and CMS content on the performance of the membranes have been studied. It is found that the addition of CMS can improve pervaporation behavior of PDMS membranes to some extent and greatly increases the strength

Lei Li; Zeyi Xiao; Zhibing Zhang; Shujuan Tan

2004-01-01

402

Adsorption of acid dyes on to granular activated carbon in fixed beds  

Microsoft Academic Search

This work involved the treatment of industrial wastewater from a nylon-carpet printing plant in Northern Ireland which currently receives no treatment and is discharged straight to sea. As nylon is particularly difficult to dye, acid dyes are required for successful colouration, but they cause major problems with the plant's effluent disposal. Granular activated carbon Filtrasorb 400 was used to treat

G. M. Walker; L. R. Weatherley

1997-01-01

403

One Carbon Metabolism in Anaerobic Bacteria: Organic Acid and Methane Production. Final Technical Report.  

National Technical Information Service (NTIS)

Organic acids (i.e acetate and butyrate) and methane are respectively important as a chemical commodity and a fuel source for industry. Both of these products can be generated via bacterial fermentation of single carbon compounds (i.e, H sub 2 /CO sub 2 ,...

J. G. Zeikus

1985-01-01

404

Elution of zinc in dust discharged from electric arc furnace in carbonic acid solution  

Microsoft Academic Search

The dust discharged from an electric arc furnace (EAF) is a valuable resource of zinc. As a fundamental study of extraction of zinc, iron and chlorine in the EAF dust, the elution behavior of them in carbonic acid solution was studied. The influence of the weight of the EAF dust on the elution behavior was examined in this study. Experiment

S Yokoyama; T Sasaki; J Sasano; M Izaki

2012-01-01

405

Highly ordered macro-mesoporous carbon nitride film for selective detection of acidic/basic molecules.  

PubMed

Well-ordered meso-macroporous carbon nitride film fabricated via a simple and flexible template replication method by using the P123 block copolymer and polystyrene spheres as dual templates shows selective sensing performance for acetic acid but after treating the surface of the film with UV light and oxygen, the selectivity of sensing can be tuned for basic molecules. PMID:24763940

Jia, Lichao; Wang, Hongqiang; Dhawale, Dattatray; Anand, Chokkalingam; Wahab, Mohammad A; Ji, Qingmin; Ariga, Katsuhiko; Vinu, Ajayan

2014-06-01

406

From pore scale to wellbore scale: Impact of geometry on wormhole growth in carbonate acidization  

Microsoft Academic Search

Acid injection in carbonate reservoir is commonly used in the oil industry to improve, or at least recover, its productivity. The aim of this stimulation technique is to create empty channels called wormholes which, if successful, would bypass the damaged area near the wellbore. During production, wormholes become pathways for the reservoir oil to reach the well. This technique increases

Charles Edouard Cohen; Didier Ding; Michel Quintard; Brigitte Bazin

2008-01-01

407

Carbon isotope composition of low molecular weight hydrocarbons and monocarboxylic acids from Murchison meteorite  

Microsoft Academic Search

Carbon isotopic compositions have been measured for individual hydrocarbons and monocarboxylic acids from the Murchison meteorite, a C2 carbonaceous chondrite which fell in Australia in 1969. With few exceptions, notably benzene, the volatile products are substantially isotopically heavier than their terrestrial counterparts, signifying their extraterrestrial origin. For both classes of compounds, the ratio of C-13 to C-12 decreases with increasing

George Yuen; Neal Blair; D. J. Des Marais; Sherwood Chang

1984-01-01

408

Activated carbons by pyrolysis of coffee bean husks in presence of phosphoric acid  

Microsoft Academic Search

Activated carbons (Acs) were prepared by pyrolysis of coffee bean husks in presence of phosphoric acid (chemical activities). Husks from Colombian coffee beans were impregnated with aqueous solutions of H3PO4 following a variant of the incipient wetness method. Diffenent concentrations were used to produce impregnation ratios of 30, 60, 100 and 150 wt.%. Activation was carried out under argon flow

M. C. Baquero; L. Giraldo; J. C. Moreno; F. Suárez-Garc??a; A. Mart??nez-Alonso; J. M. D. Tascón

2003-01-01

409

Graphene-carbon nanotube composite aerogel for selective detection of uric acid  

NASA Astrophysics Data System (ADS)

Graphene and single-walled carbon nanotube (SWNT) composite aerogel has been prepared by hydrothermal synthesis. The restacking of graphene is effectively reduced by SWNTs inserted in between graphene layers in order to make available more active sites and reactive surface area. Electrochemical experiments show that the graphene-SWNT composite electrode has superior catalytic performance in selective detection of uric acid (UA).

Zhang, Feifei; Tang, Jie; Wang, Zonghua; Qin, Lu-Chang

2013-12-01

410

Carbon Isotopic Ratios of Amino Acids in Stardust-Returned Samples  

NASA Technical Reports Server (NTRS)

NASA's Stardust spacecraft returned to Earth samples from comet 81P/Wild 2 in January 2006. Preliminary examinations revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds could not be identified. Here. we present the carbon isotopic ratios of glycine and E-aminocaproic acid (EACH), the two most abundant amino acids observed, in Stardust-returned foil samples measured by gas chromatography-combustion-isotope ratio crass spectrometry coupled with quadrupole mass spectrometry (GC-QMS/IRMS).

Elsila, Jamie E.; Glavin, Daniel P.; Dworkin, Jason P.

2009-01-01

411

Carbon Isotopic Measurements of Amino Acids in Stardust-Returned Samples  

NASA Technical Reports Server (NTRS)

NASA's Stardust spacecraft returned to Earth samples from comet 81P/Wild 2 in January 2006. Preliminary examinations revealed the presence of a suite of organic compounds including several amines and amino acids, but the origin of these compounds could not be identified. Here, we present the carbon isotopic ratios of glycine and e-aminocaproic acid (EACA), the two most abundant amino acids, in Stardust-returned foil samples measured by gas chromatography-combustion-isotope ratio mass spectrometry coupled with quadrupole mass spectrometry (GC-CAMS/IRMS).

Elsila, Jamie

2009-01-01

412

Artificial photosynthesis of. beta. -ketocarboxylic acids from carbon dioxide and ketones via enolate complexes of aluminum porphyrin  

Microsoft Academic Search

Photochemical fixation of carbon dioxide is of much interest in connection with biological photosynthesis by green plants as well as from the viewpoint of carbon resource utilization. One of the important steps in the assimilation of carbon dioxide is the carboxylation of a carbonyl compound into ketocarboxylic acid, where the reaction proceeds via an enolate species as reactive intermediate. For

Yasuhiro Hirai; Takuzo Aida; Shohei Inoue

1989-01-01

413

Whole-body pharmacokinetics of HDAC inhibitor drugs, butyric acid, valproic acid and 4-phenylbutyric acid measured with carbon-11 labeled analogs by PET.  

PubMed

The fatty acids, n-butyric acid (BA), 4-phenylbutyric acid (PBA) and valproic acid (VPA, 2-propylpentanoic acid) have been used for many years in the treatment of a variety of CNS and peripheral organ diseases including cancer. New information that these drugs alter epigenetic processes through their inhibition of histone deacetylases (HDACs) has renewed interest in their biodistribution and pharmacokinetics and the relationship of these properties to their therapeutic and side effect profiles. In order to determine the pharmacokinetics and biodistribution of these drugs in primates, we synthesized their carbon-11 labeled analogues and performed dynamic positron emission tomography (PET) in six female baboons over 90 min. The carbon-11 labeled carboxylic acids were prepared by using (11)CO2 and the appropriate Grignard reagents. [(11)C]BA was metabolized rapidly (only 20% of the total carbon-11 in plasma was parent compound at 5 min post injection) whereas for VPA and PBA 98% and 85% of the radioactivity were the unmetabolized compound at 30 min after their administration respectively. The brain uptake of all three carboxylic acids was very low (<0.006%ID/cc, BA>VPA>PBA), which is consistent with the need for very high doses for therapeutic efficacy. Most of the radioactivity was excreted through the kidneys and accumulated in the bladder. However, the organ biodistribution between the drugs differed. [(11)C]BA showed relatively high uptake in spleen and pancreas whereas [(11)C]PBA showed high uptake in liver and heart. Notably, [(11)C]VPA showed exceptionally high heart uptake possibly due to its involvement in lipid metabolism. The unique biodistribution of each of these drugs may be of relevance in understanding their therapeutic and side effect profile including their teratogenic effects. PMID:23906667

Kim, Sung Won; Hooker, Jacob M; Otto, Nicola; Win, Khaing; Muench, Lisa; Shea, Colleen; Carter, Pauline; King, Payton; Reid, Alicia E; Volkow, Nora D; Fowler, Joanna S

2013-10-01

414

Adsorption of clofibric acid and ketoprofen onto powdered activated carbon: effect of natural organic matter.  

PubMed

The adsorption of two acidic pharmaceutically active compounds (PhACs), clofibric acid and ketoprofen, onto powdered activated carbon (PAC) was investigated with a particular focus on the influence of natural organic matter (NOM) on the adsorption of the PhACs. Suwannee River humic acids (SRHAs) were used as a substitute for NOM. Batch adsorption experiments were conducted to obtain adsorption kinetics and adsorption isotherms with and without SRHAs in the system. The adsorption isotherms and adsorption kinetics showed that the adsorption ofclofibric acid was not significantly affected by the presence of SRHAs at a concentration of 5 mg (as carbon) L(-1). An adsorption capacity of 70 to 140 mg g(-1) was observed and equilibrium was reached within 48 h. In contrast, the adsorption of ketoprofen was markedly decreased (from about 120 mg g(-1) to 70-100 mg g(-1)) in the presence of SRHAs. Higher initial concentrations of clofibric acid than ketoprofen during testing may explain the different behaviours that were observed. Also, the more hydrophobic ketoprofen molecules may have less affinity for PAC when humic acids (which are hydrophilic) are present. The possible intermolecular forces that could account for the different behaviour of clofibric acid and ketoprofen adsorption onto PAC are discussed. In particular, the relevance of electrostatic forces, electron donor-acceptor interaction, hydrogen bonding and London dispersion forces are discussed PMID:22439557

Gao, Yaohuan; Deshusses, Marc A

2011-12-01

415

Improving stable carbon and oxygen isotope geochemical measurements in dolomite: reference material and acid fractionation factor  

NASA Astrophysics Data System (ADS)

The analysis of stable carbon and oxygen isotope composition is one of the most commonly used techniques in stratigraphic and diagenetic research of carbonate rocks. The wide-spread use and easy access of this long-established method has the side effect that little attention is paid to fundamental calibrations. Dolomite is often measured against a calcite standard (NBS19), and the acid fractionation factor used to calibrate is based on the one for calcite. To date, no reference material exists for dolomite. In this study, which is part of dolomite research in the Qatar Carbonates and Carbon Storage Research Centre project, we focus on two main goals. First, we characterize a current standard of dolomite used for major and minor elemental geochemistry, and assess its suitability as a new dolomite standard for ?18O and ?13C. Second, we attempt to better constrain the acid fractionation factor for dolomite and assess the influence of different dolomite types on this fractionation factor. As only two third of the total oxygen in the carbonate is released in the form of CO2 during acid reaction, a fractionation between the reacting carbonate and the resulting gas will occur. A recent study by Kim et al. (2007) improved on the acid fractionation factors for calcite and aragonite. Often, the acid fractionation factor for dolomite is used to calculate ?18O and ?13C from the values obtained by calibration with the calcite standard. Only two studies (from the 1980’s) have attempted to constrain the acid fractionation factor for dolomite, of which only Rosenbaum and Sheppard (1986) did experiments not only at 25°C, but also at 50 and 100°C. The dataset of the latter authors is, however, very limited and contains only two dolomite samples. We aim at improving the constraints on the acid fractionation factor of dolomite by reacting a wide range of different types of dolomite at a wide range of acid temperature, and compare this to the absolute isotopic composition of the samples measured on a fluorination line.

Vandeginste, V.; John, C. M.; Jourdan, A.; Davis, S.

2010-12-01

416

Effects of sulfuric acid treatment on the microstructure and electrochemical performance of a polyacrylonitrile (PAN)-based carbon anode  

Microsoft Academic Search

To examine whether acid treatment of a non-graphitizing hard carbon influences positively or negatively its electrochemical anodic performance, this study reports the effects of sulfuric acid treatment on the microstructural changes and electrochemical performance of PAN-based hard carbons prepared at various temperatures. It was found that PAN-based hard carbons heat treated at 900°C (TAN9) exhibit an increased reversible capacity by

Y. J. Kim; H. J. Lee; S. W. Lee; B. W. Cho; C. R. Park

2005-01-01

417

Stable carbon isotopic compositions of total carbon, dicarboxylic acids and glyoxylic acid in the tropical Indian aerosols: Implications for sources and photochemical processing of organic aerosols  

NASA Astrophysics Data System (ADS)

The tropical Indian aerosols (PM10) collected on day- and nighttime bases in winter and summer, 2007 from Chennai (13.04°N; 80.17°E) were studied for stable carbon isotopic compositions (?13C) of total carbon (TC), individual dicarboxylic acids (C2-C9) and glyoxylic acid (?C2). ?13C values of TC ranged from -23.9‰ to -25.9‰ (-25.0 ± 0.6‰; n = 49). Oxalic (C2) (-17.1 ± 2.5‰), malonic (C3) (-20.8 ± 1.8‰), succinic (C4) (-22.5 ± 1.5‰) and adipic (C6) (-20.6 ± 4.1‰) acids and ?C2 acid (-22.4 ± 5.5‰) were found to be more enriched with 13C compared to TC. In contrast, suberic (C8) (-29.4 ± 1.8‰), phthalic (Ph) (-30.1 ± 3.5‰) and azelaic (C9) (-28.4 ± 5.8‰) acids showed smaller ?13C values than TC. Based on comparisons of ?13C values of TC in Chennai aerosols to those (-24.7 ± 2.2‰) found in unburned cow-dung samples collected from Chennai and isotopic signatures of the particles emitted from point sources, we found that biofuel/biomass burning are the major sources of carbonaceous aerosols in South and Southeast Asia. The decrease in ?13C values of C9 diacid by about 5‰ from winter to summer suggests that tropical plant emissions also significantly contribute to organic aerosol in this region. Significant increase in ?13C values from C4 to C2 diacids in Chennai aerosols could be attributed for their photochemical processing in the tropical atmosphere during long-range transport from source regions.

Pavuluri, Chandra Mouli; Kawamura, Kimitaka; Swaminathan, T.; Tachibana, Eri

2011-09-01

418

The healing effect of stearic acid applied on amorphous carbon film with dispersed nanodiamonds  

NASA Astrophysics Data System (ADS)

Diamond-like carbon (DLC) films have been shown to improve the friction and wear properties of applications with severe loads. Hydrogenated amorphous carbon films (a-C:H), a type of DLC film, were coated onto 440C stainless steel disk surfaces. The plasma enhanced chemical vapour deposition method was used as a coating process, and nanodiamond (ND) particles were dispersed into the film during the deposition process. Stearic acid was expected to affect the lubricating properties of the film because of its reported effectiveness on diamond surfaces. A lubricated reciprocal sliding friction test with 10,000 cycles confirmed that stearic acid improved the friction and wear properties of the ND dispersed a-C:H film. Furthermore, film wear caused by a sliding test without stearic acid could be healed by sliding with stearic acid as long as the level of critical damage was not reached. Raman spectra for the worn tracks revealed the healing effect of the stearic acid on the film because the spectra for the worn tracks after 10,000 cycles were identical to those of the control film, which was not worn. In contrast, the spectra for the worn tracks or debris showed a broad D band peak and no G peak, which was consistent with disordered amorphous carbon.

Yamazaki, T.; Shoji, K.; Ikeshoji, T.-T.; Suzumura, A.

2012-08-01

419

Adsorption equilibrium, kinetics and thermodynamics of dichloroacetic acid from aqueous solution using mesoporous carbon.  

PubMed

The presence of disinfection by-products, such as trihalomethanes and haloacetic acids in water, is believed to be harmful to human health. In this work, mesoporous carbon was synthesized with the evaporation-induced self-assembly method and employed to evaluate the effects of initial concentration, contact time, pH and temperature on the removal of dichloroacetic acid in batch experiments. Adsorption equilibrium was established in 480 min and the maximum adsorption (350mg/g) of dichloroacetic acid on the mesoporous carbon was observed to occur at 308 K and pH 3.0. Freundlich and Langmuir isotherms were used to analyse the equilibrium data at different temperatures; kinetic data were fitted to the pseudo-first-order and pseudo-second-order models and found that the adsorption capacity, mass transfer coefficient and diffusivity of dichloroacetic acid were directly affected by the physical and chemical parameters. In addition, the various thermodynamic parameters, such as Gibbs free energy (Delta G), enthalpy (Delta H = 54.35 kJmol-1) and entropy (Delta S = 258.36 Jmol-1 K-1) were calculated to analyse the adsorption process. The experimental results indicated that the mesoporous carbon was an excellent adsorbent for dichloroacetic acid removal from aqueous solutions. PMID:24956790

Ding, Ying; Zhu, Jianzhong; Cao, Yang; Chen, Shenglu

2014-08-01

420

Pd-loaded carbon felt as the cathode for selective dechlorination of 2,4-dichlorophenoxyacetic acid in aqueous solution  

SciTech Connect

Electrocatalytic reductive dehalogenation of 2,4-dichlorophenoxyacetic acid (2,4-D) to phenoxyacetic acid in aqueous solution containing MeOH, trifluoroacetic acid, and tetraalkylammonium salt was studied. A Teflon-made two-compartment flow-through cell with a permeable carbon felt cathode and a platinum foil anode was employed. Several noble metals were tested as electrocatalysts. Palladium-loaded carbon felt was found to be the most suitable significantly enhanced its electrocatalytic activity toward 2,4-D dechlorination. The reaction was hypothesized to proceed at carbon-palladium interface areas through 4-chlorine cleavage to form 2-chlorophenoxyacetic acid as the main reaction intermediate.

Tsyganok, A.I.; Yamanaka, Ichiro; Otsuka, Kiyoshi [Tokyo Inst. of Tech. (Japan). Dept. of Chemical Engineering

1998-11-01

421

One carbon metabolism in anaerobic bacteria: Regulation of carbon and electron flow during organic acid production  

SciTech Connect

This reporting period, progress is reported on the following: metabolic pathway of solvent production in B. methylotrophicum; the biochemical mechanism for metabolic regulation of the succinate fermentation; models to understand the physiobiochemical function of formate metabolism in anaerobes and; models for understanding the influence of low pH on one carbon metabolism. (CBS)

Zeikus, J.G.; Jain, M.K.

1992-01-01

422

Hydrogen-bond acidic functionalized carbon nanotubes (CNTs) with covalently-bound hexafluoroisopropanol groups  

SciTech Connect

Fluorinated hydrogen-bond acidic groups are directly attached to the backbone of single walled carbon nanotubes (SWCNTs) without the introduction of intermediate electron donating surface groups. Hexafluoroalcohol functional groups are exceptionally strong hydrogen bond acids, and are added to the nanotube surface using the aryl diazonium approach to create hydrogen-bond acidic carbon nanotube (CNT) surfaces. These groups can promote strong hydrogen-bonding interactions with matrix materials in composites or with molecular species to be concentrated and sensed. In the latter case, this newly developed material is expected to find useful application in chemical sensors and in CNT-based preconcentrator devices for the detection of pesticides, chemical warfare agents and explosives.

Fifield, Leonard S.; Grate, Jay W.

2010-06-01

423

Planetary rover robotics experiment in education: carbonate rock collecting experiment of the Husar-5 rover of the Szechenyistvan high school, Sorpon, Hungary  

NASA Astrophysics Data System (ADS)

The new experiment for the Husar-5 educational space probe rover consists of steps of the technology of procedure of finding carbonate specimens among the rocks on the field. 3 main steps were robotized: 1) identification of carbonate by acid test, 2) measuring the gases liberated by acid, and 3)magnetic test.

Lang, A.; Prajczer, P.; Bérczi, Sz.

2013-09-01

424

Synthesis and acid catalysis of zeolite-templated microporous carbons with SO3H groups.  

PubMed

Microporous carbon catalysts with large surface areas (800-1100 m(2) g(-1)) and high densities of SO3H groups (ca. 1.1 mmol g(-1)) were synthesized by sulfonation of zeolite-templated microporous carbon. The resulting SO3H-bearing microporous carbon catalysts exhibited higher catalytic performance for the hydrolysis of cellobiose and the Beckmann rearrangement than conventional solid acid catalysts and non-porous amorphous carbon with SO3H groups. The high catalytic activity of these reusable heterogeneous catalysts can be attributed to the high surface area and microporous structure, which enhance the efficient incorporation and diffusion of reactant molecules from solution to the SO3H groups on the catalysts. PMID:23660580

Fukuhara, Kiichi; Nakajima, Kiyotaka; Kitano, Masaaki; Hayashi, Shigenobu; Hara, Michikazu

2013-06-21

425

Rheology of molten polystyrene with dissolved gases  

Microsoft Academic Search

Dissolved gases in polymers behave as excellent plasticizers, reducing viscosity significantly through the chain dilution effect and the addition of free volume. Rheological measurements and theoretical modeling are presented for molten polystyrene with dissolved gases, including carbon dioxide, 1,1-difluoroethane (R152a), and 1,1,1,2-tetrafluoroethane (R134a), which are considered to be environmentally acceptable for replacing previous ozone-depleting hydrochlorocarbon (HFC) refrigerants.^ A modified pressurized

Choongyong Kwag

1998-01-01

426

Adsorption Characteristics of 2,4-Dichlorophenoxyacetic Acid (2,4-D) from Aqueous Solution on Powdered Activated Carbon  

Microsoft Academic Search

The removal of 2,4-dichlorophenoxyacetic acid (2,4-D), one of the most commonly used phenoxy acid herbicides, from aqueous solution was studied by using acid-washed powdered activated carbon (PAC) as an adsorbent in a batch system. Adsorption equilibrium, kinetics, and thermodynamics were investigated as a function of initial pH, temperature, and initial 2,4-D concentration. Powdered activated carbon exhibited the highest 2,4-D uptake

Z. AKSU; E. KABASAKAL

2005-01-01

427

Pd-loaded carbon felt as the cathode for selective dechlorination of 2,4-dichlorophenoxyacetic acid in aqueous solution  

Microsoft Academic Search

Electrocatalytic reductive dehalogenation of 2,4-dichlorophenoxyacetic acid (2,4-D) to phenoxyacetic acid in aqueous solution containing MeOH, trifluoroacetic acid, and tetraalkylammonium salt was studied. A Teflon-made two-compartment flow-through cell with a permeable carbon felt cathode and a platinum foil anode was employed. Several noble metals were tested as electrocatalysts. Palladium-loaded carbon felt was found to be the most suitable significantly enhanced its

Andrey I. Tsyganok; Ichiro Yamanaka; Kiyoshi Otsuka

1998-01-01

428

Solubilities of stearic acid, stearyl alcohol, and arachidyl alcohol in supercritical carbon dioxide at 35[degree]C  

SciTech Connect

The solubilities of stearic acid (octadecanoic acid), stearyl alcohol (1-octadecanol), and arachidyl alcohol (1-eicosanol) in supercritical carbon dioxide were measured by using a flow-type apparatus at 35 C up to 23.7 MPa. The solubilities of those substances and other fatty acids and higher alcohols in supercritical carbon dioxide at 35 C were correlated by a solution model based on the regular solution model coupled with the Flory-Huggins theory.

Iwai, Yoshio; Koga, Yoshio; Maruyama, Hironori; Arai, Yasuhiko (Kyushu Univ., Fukuoka (Japan). Dept. of Chemical Engineering)

1993-10-01