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Sample records for calcium carbonate storage

  1. Organoaqueous calcium chloride electrolytes for capacitive charge storage in carbon nanotubes at sub-zero-temperatures.

    PubMed

    Gao, Yun; Qin, Zhanbin; Guan, Li; Wang, Xiaomian; Chen, George Z

    2015-07-11

    Solutions of calcium chloride in mixed water and formamide are excellent electrolytes for capacitive charge storage in partially oxidised carbon nanotubes at unprecedented sub-zero-temperatures (e.g. 67% capacitance retention at -60 °C).

  2. Calcium Carbonate

    MedlinePlus

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  3. Calcium Carbonate.

    PubMed

    Al Omari, M M H; Rashid, I S; Qinna, N A; Jaber, A M; Badwan, A A

    2016-01-01

    Calcium carbonate is a chemical compound with the formula CaCO3 formed by three main elements: carbon, oxygen, and calcium. It is a common substance found in rocks in all parts of the world (most notably as limestone), and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. CaCO3 exists in different polymorphs, each with specific stability that depends on a diversity of variables.

  4. Calcium Carbonate.

    PubMed

    Al Omari, M M H; Rashid, I S; Qinna, N A; Jaber, A M; Badwan, A A

    2016-01-01

    Calcium carbonate is a chemical compound with the formula CaCO3 formed by three main elements: carbon, oxygen, and calcium. It is a common substance found in rocks in all parts of the world (most notably as limestone), and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. CaCO3 exists in different polymorphs, each with specific stability that depends on a diversity of variables. PMID:26940168

  5. Calcium carbonate overdose

    MedlinePlus

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Some products that contain calcium carbonate are certain: ... and mineral supplements Other products may also contain calcium ...

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

    PubMed

    Comănescu, Cezar; Capurso, Giovanni; Maddalena, Amedeo

    2012-09-28

    Mesoporous carbon frameworks were synthesized using the soft-template method. Ca(BH(4))(2) was incorporated into activated mesoporous carbon by the incipient wetness method. The activation of mesoporous carbon was necessary to optimize the surface area and pore size. Thermal programmed absorption measurements showed that the confinement of this borohydride into carbon nanoscaffolds improved its reversible capacity (relative to the reactive portion) and performance of hydrogen storage compared to unsupported borohydride. Hydrogen release from the supported hydride started at a temperature as low as 100 °C and the dehydrogenation rate was fast compared to the bulk borohydride. In addition, the hydrogen pressure necessary to regenerate the borohydride from the dehydrogenation products was reduced. PMID:22948563

  7. Calcium Carbonate Storage in Amorphous Form and Its Template-Induced Crystallization

    SciTech Connect

    Han, T Y; Aizenberg, J

    2007-08-31

    Calcium carbonate crystallization in organisms often occurs through the transformation from the amorphous precursor. It is believed that the amorphous phase could be temporarily stabilized and stored, until its templated transition to the crystalline form is induced. Here we develop a bio-inspired crystallization strategy that is based on the above mechanism. Amorphous calcium carbonate (ACC) spherulitic particles are formed and stabilized on a self-assembled monolayer (SAM) of hydroxy-terminated alkanethiols on Au surface. The ACC is stored as a reservoir for ions and is induced to crystallize on command by introducing a secondary surface that is functionalized with carboxylic acid-terminated SAM. This secondary surface acts as a template for oriented and patterned nucleation. Various oriented crystalline arrays and micropatterned films are formed. We also show that the ACC phase can be doped with foreign ions (e.g. Mg) and organic molecules (e.g. dyes) and that these dopants later function as growth modifiers of calcite crystals and become incorporated into the crystals during the transformation process of ACC to calcite. We believe that our strategy opens the way of using a stabilized amorphous phase as a versatile reservoir system that can be converted in a highly controlled fashion to a crystalline form upon contacting the nucleating template.

  8. 21 CFR 184.1191 - Calcium carbonate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the “Carbonation process”; or (3) By precipitation of calcium carbonate from calcium chloride in the “Calcium...

  9. 21 CFR 184.1191 - Calcium carbonate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the “Carbonation process”; or (3) By precipitation of calcium carbonate from calcium chloride in the “Calcium...

  10. 21 CFR 184.1191 - Calcium carbonate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the “Carbonation process”; or (3) By precipitation of calcium carbonate from calcium chloride in the “Calcium...

  11. 21 CFR 184.1191 - Calcium carbonate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the “Carbonation process”; or (3) By precipitation of calcium carbonate from calcium chloride in the “Calcium...

  12. Calcium carbonate with magnesium overdose

    MedlinePlus

    The combination of calcium carbonate and magnesium is commonly found in antacids. These medicines provide heartburn relief. Calcium carbonate with magnesium overdose occurs when someone takes more than the ...

  13. Impregnating Coal With Calcium Carbonate

    NASA Technical Reports Server (NTRS)

    Sharma, Pramod K.; Voecks, Gerald E.; Gavalas, George R.

    1991-01-01

    Relatively inexpensive process proposed for impregnating coal with calcium carbonate to increase rates of gasification and combustion of coal and to reduce emission of sulfur by trapping sulfur in calcium sulfide. Process involves aqueous-phase reactions between carbon dioxide (contained within pore network of coal) and calcium acetate. Coal impregnated with CO2 by exposing it to CO2 at high pressure.

  14. Calcium as a superior coating metal in functionalization of carbon fullerenes for high-capacity hydrogen storage

    SciTech Connect

    Yoon, Mina; Yang, Shenyuan; Hicke, Christian; Wang, Enge; Geohegan, David B; Zhang, Zhenyu

    2008-01-01

    We explore theoretically the feasibility of functionalizing carbon nanostructures for hydrogen storage, focusing on the coating of C60 fullerenes with light alkaline-earth metals. Our first-principles density functional theory studies show that both Ca and Sr can bind strongly to the C60 surface, and highly prefer monolayer coating, thereby explaining existing experimental observations. The strong binding is attributed to an intriguing charge transfer mechanism involving the empty d levels of the metal elements. The charge redistribution, in turn, gives rise to electric fields surrounding the coated fullerenes, which can now function as ideal attractors upon molecular hydrogen adsorption with binding strengths strong enough for potential room temperature applications but weak enough to avoid H2 dissociation. With a hydrogen uptake of >8.4wt% on Ca32C60, Ca is superior to all the recently suggested metal coating elements.

  15. Heat storage material comprising calcium chloride-hexahydrate and a nucleating agent

    SciTech Connect

    Gawron, K.; Schroder, J.

    1980-02-19

    The utility of calcium chloride-hexahydrate as a heat storage material is improved when barium carbonate, strontium carbonate, barium fluoride, barium fluoride-hydrofluoride and/or strontium fluoride is used as a nucleating agent to prevent supercooling.

  16. Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

    ERIC Educational Resources Information Center

    Henrickson, Charles H.; Robinson, Paul R.

    1979-01-01

    The gravimetric determination of calcium as calcium carbonate is described. This experiment is suitable for undergraduate quantitative analysis laboratories. It is less expensive than determination of chloride as silver chloride. (BB)

  17. 21 CFR 582.5191 - Calcium carbonate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  18. 21 CFR 582.5191 - Calcium carbonate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  19. 21 CFR 582.5191 - Calcium carbonate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  20. 21 CFR 582.5191 - Calcium carbonate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  1. 21 CFR 582.5191 - Calcium carbonate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  2. 21 CFR 184.1191 - Calcium carbonate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... three common methods of manufacture: (1) As a byproduct in the “Lime soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the “Carbonation process”; or (3) By precipitation...

  3. 21 CFR 582.1191 - Calcium carbonate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium carbonate. 582.1191 Section 582.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  4. 21 CFR 73.1070 - Calcium carbonate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1070 Calcium carbonate. (a) Identity. (1) The color additive calcium carbonate is a fine, white, synthetically prepared powder consisting essentially...

  5. 21 CFR 582.1191 - Calcium carbonate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Calcium carbonate. 582.1191 Section 582.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  6. 21 CFR 73.1070 - Calcium carbonate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1070 Calcium carbonate. (a) Identity. (1) The color additive calcium carbonate is a fine, white, synthetically prepared powder consisting essentially...

  7. 21 CFR 582.1191 - Calcium carbonate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Calcium carbonate. 582.1191 Section 582.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  8. 21 CFR 73.1070 - Calcium carbonate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1070 Calcium carbonate. (a) Identity. (1) The color additive calcium carbonate is a fine, white, synthetically prepared powder consisting essentially...

  9. 21 CFR 73.1070 - Calcium carbonate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1070 Calcium carbonate. (a) Identity. (1) The color additive calcium carbonate is a fine, white, synthetically prepared powder consisting essentially...

  10. 21 CFR 582.1191 - Calcium carbonate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Calcium carbonate. 582.1191 Section 582.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  11. 21 CFR 73.1070 - Calcium carbonate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1070 Calcium carbonate. (a) Identity. (1) The color additive calcium carbonate is a fine, white, synthetically prepared powder consisting essentially...

  12. 21 CFR 582.1191 - Calcium carbonate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Calcium carbonate. 582.1191 Section 582.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use....

  13. Characterization of calcium carbonate/chitosan composites

    SciTech Connect

    Gonsalves, K.E.; Zhang, S.

    1995-12-31

    The crystal growth of calcium carbonate on a chitosan substrate was achieved using a supersaturated calcium carbonate solution, by using various additives, polyacrylic acid (PAA). Polyacrylic acid modified the chitosan-film surface and promoted the nucleation of calcium carbonate crystals.

  14. Preparation and Characterization of Calcium Carbonate Nanoparticles

    NASA Astrophysics Data System (ADS)

    Hassim, Aqilah; Rachmawati, Heni

    2010-10-01

    Taking calcium supplements can reduce the risk of developing osteoporosis, but they are not readily absorbed in the gastrointestinal tract. Nanotechnology is expected to resolve this problem. In this study, we prepared and characterized calcium carbonate nanoparticle to improve the solubility by using bottom-up method. The experiment was done by titrating calcium chloride with sodium carbonate with the addition of polyvinylpyrrolidone (PVP) as stabilizer, using ultra-turrax. Various concentrations of calcium chloride and sodium carbonate as well as various speed of stirring were used to prepare the calcium carbonate nanoparticles. Evaluations studied were including particle size, polydispersity index (PI) and zeta potential with particle analyzer, surface morphology with scanning electron microscope, and saturated solubility. In addition, to test the ability of PVP to prevent particles growth, short stability study was performed by storing nano CaCO3 suspension at room temperature for 2 weeks. Results show that using 8000 rpm speed of stirring, the particle size tends to be bigger with the range of 500-600 nm (PI between 0.2-0.4) whereas with stirring speed of 4000 rpm, the particle size tends to be smaller with 300-400 nm (PI between 0.2-0.4). Stirring speed of 6000 rpm produced particle size within the range of 400-500 nm (PI between 0.2-0.4). SEM photograph shows that particles are monodisperse confirming that particles were physically stable without any agglomeration within 2 weeks storage. Taken together, nano CaCO3 is successfully prepared by bottom-up method and PVP is a good stabilizer to prevent the particle growth.

  15. Biologically formed amorphous calcium carbonate.

    PubMed

    Weiner, Steve; Levi-Kalisman, Yael; Raz, Sefi; Addadi, Lia

    2003-01-01

    Many organisms from a wide variety of taxa produce amorphous calcium carbonate (ACC), despite the fact that it is inherently unstable and relatively soluble in its pure state. These properties also make it difficult to detect and characterize ACC. Raman spectroscopy is a particularly useful method for investigating ACC because the sample can be examined wet, and extended X-ray absorption fine structure (EXAFS) analysis can provide detailed information on the short-range order. Other methods for characterizing ACC include infrared spectroscopy, thermogravimetric analysis and differential thermal analysis (TGA and DTA), transmission electron microscopy (TEM), and electron and X-ray diffraction. Because of the difficulties involved, we suspect that ACC is far more widely distributed than is presently known, and a comparison of EXAFS spectra shows that different biogenic ACC phases have different short-range order structures. We also suspect that ACC fulfils many different functions, including as a transient precursor phase during the formation of crystalline calcium carbonate.

  16. Spinning up the polymorphs of calcium carbonate

    PubMed Central

    Boulos, Ramiz A.; Zhang, Fei; Tjandra, Edwin S.; Martin, Adam D.; Spagnoli, Dino; Raston, Colin L.

    2014-01-01

    Controlling the growth of the polymorphs of calcium carbonate is important in understanding the changing environmental conditions in the oceans. Aragonite is the main polymorph in the inner shells of marine organisms, and can be readily converted to calcite, which is the most stable polymorph of calcium carbonate. Both of these polymorphs are significantly more stable than vaterite, which is the other naturally occurring polymorph of calcium carbonate, and this is reflected in its limited distribution in nature. We have investigated the effect of high shear forces on the phase behaviour of calcium carbonate using a vortex fluidic device (VFD), with experimental parameters varied to explore calcium carbonate mineralisation. Variation of tilt angle, rotation speed and temperature allow for control over the size, shape and phase of the resulting calcium carbonate. PMID:24448077

  17. Carbon Capture and Storage

    SciTech Connect

    Friedmann, S

    2007-10-03

    Carbon capture and sequestration (CCS) is the long-term isolation of carbon dioxide from the atmosphere through physical, chemical, biological, or engineered processes. This includes a range of approaches including soil carbon sequestration (e.g., through no-till farming), terrestrial biomass sequestration (e.g., through planting forests), direct ocean injection of CO{sub 2} either onto the deep seafloor or into the intermediate depths, injection into deep geological formations, or even direct conversion of CO{sub 2} to carbonate minerals. Some of these approaches are considered geoengineering (see the appropriate chapter herein). All are considered in the 2005 special report by the Intergovernmental Panel on Climate Change (IPCC 2005). Of the range of options available, geological carbon sequestration (GCS) appears to be the most actionable and economic option for major greenhouse gas reduction in the next 10-30 years. The basis for this interest includes several factors: (1) The potential capacities are large based on initial estimates. Formal estimates for global storage potential vary substantially, but are likely to be between 800 and 3300 Gt of C (3000 and 10,000 Gt of CO{sub 2}), with significant capacity located reasonably near large point sources of the CO{sub 2}. (2) GCS can begin operations with demonstrated technology. Carbon dioxide has been separated from large point sources for nearly 100 years, and has been injected underground for over 30 years (below). (3) Testing of GCS at intermediate scale is feasible. In the US, Canada, and many industrial countries, large CO{sub 2} sources like power plants and refineries lie near prospective storage sites. These plants could be retrofit today and injection begun (while bearing in mind scientific uncertainties and unknowns). Indeed, some have, and three projects described here provide a great deal of information on the operational needs and field implementation of CCS. Part of this interest comes from several

  18. [Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

    PubMed

    de Jonge, H J M Henk-Marijn; Gans, R O B Rijk; Huls, Gerwin

    2012-01-01

    Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate absorption. No convincing scientific evidence supporting the advice to prescribe calcium citrate instead of calcium carbonate to patients who also take antacids is available, and therefore deserves further investigation. On the contrary, the fact that calcium carbonate does not need acid in order to be absorbed, has also not been proven. In clinical practise, it appears important that calcium is taken with meals in order to improve its absorption. PMID:22914054

  19. [Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

    PubMed

    de Jonge, H J M Henk-Marijn; Gans, R O B Rijk; Huls, Gerwin

    2012-01-01

    Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate absorption. No convincing scientific evidence supporting the advice to prescribe calcium citrate instead of calcium carbonate to patients who also take antacids is available, and therefore deserves further investigation. On the contrary, the fact that calcium carbonate does not need acid in order to be absorbed, has also not been proven. In clinical practise, it appears important that calcium is taken with meals in order to improve its absorption.

  20. Carbon Capture and Storage, 2008

    SciTech Connect

    2009-03-19

    The U.S. Department of Energy is researching the safe implementation of a technology called carbon sequestration, also known as carbon capture and storage, or CCS. Based on an oilfield practice, this approach stores carbon dioxide, or CO2 generated from human activities for millennia as a means to mitigate global climate change. In 2003, the Department of Energys National Energy Technology Laboratory formed seven Regional Carbon Sequestration Partnerships to assess geologic formations suitable for storage and to determine the best approaches to implement carbon sequestration in each region. This video describes the work of these partnerships.

  1. Carbon Capture and Storage, 2008

    ScienceCinema

    None

    2016-07-12

    The U.S. Department of Energy is researching the safe implementation of a technology called carbon sequestration, also known as carbon capture and storage, or CCS. Based on an oilfield practice, this approach stores carbon dioxide, or CO2 generated from human activities for millennia as a means to mitigate global climate change. In 2003, the Department of Energys National Energy Technology Laboratory formed seven Regional Carbon Sequestration Partnerships to assess geologic formations suitable for storage and to determine the best approaches to implement carbon sequestration in each region. This video describes the work of these partnerships.

  2. Ab Initio Studies of Calcium Carbonate Hydration.

    PubMed

    Lopez-Berganza, Josue A; Diao, Yijue; Pamidighantam, Sudhakar; Espinosa-Marzal, Rosa M

    2015-11-25

    Ab initio simulations of large hydrated calcium carbonate clusters are challenging due to the existence of multiple local energy minima. Extensive conformational searches around hydrated calcium carbonate clusters (CaCO3·nH2O for n = 1-18) were performed to find low-energy hydration structures using an efficient combination of Monte Carlo searches, density-functional tight binding (DFTB+) method, and density-functional theory (DFT) at the B3LYP level, or Møller-Plesset perturbation theory at the MP2 level. This multilevel optimization yields several low-energy structures for hydrated calcium carbonate. Structural and energetics analysis of the hydration of these clusters revealed a first hydration shell composed of 12 water molecules. Bond-length and charge densities were also determined for different cluster sizes. The solvation of calcium carbonate in bulk water was investigated by placing the explicitly solvated CaCO3·nH2O clusters in a polarizable continuum model (PCM). The findings of this study provide new insights into the energetics and structure of hydrated calcium carbonate and contribute to the understanding of mechanisms where calcium carbonate formation or dissolution is of relevance.

  3. Calcium carbonate polyamorphism and its role in biomineralization: how many amorphous calcium carbonates are there?

    PubMed

    Cartwright, Julyan H E; Checa, Antonio G; Gale, Julian D; Gebauer, Denis; Sainz-Díaz, C Ignacio

    2012-11-26

    Although the polymorphism of calcium carbonate is well known, and its polymorphs--calcite, aragonite, and vaterite--have been highly studied in the context of biomineralization, polyamorphism is a much more recently discovered phenomenon, and the existence of more than one amorphous phase of calcium carbonate in biominerals has only very recently been understood. Here we summarize what is known about polyamorphism in calcium carbonate as well as what is understood about the role of amorphous calcium carbonate in biominerals. We show that consideration of the amorphous forms of calcium carbonate within the physical notion of polyamorphism leads to new insights when it comes to the mechanisms by which polymorphic structures can evolve in the first place. This not only has implications for our understanding of biomineralization, but also of the means by which crystallization may be controlled in medical, pharmaceutical, and industrial contexts.

  4. Phase transitions in biogenic amorphous calcium carbonate

    NASA Astrophysics Data System (ADS)

    Gong, Yutao

    Geological calcium carbonate exists in both crystalline phases and amorphous phases. Compared with crystalline calcium carbonate, such as calcite, aragonite and vaterite, the amorphous calcium carbonate (ACC) is unstable. Unlike geological calcium carbonate crystals, crystalline sea urchin spicules (99.9 wt % calcium carbonate and 0.1 wt % proteins) do not present facets. To explain this property, crystal formation via amorphous precursors was proposed in theory. And previous research reported experimental evidence of ACC on the surface of forming sea urchin spicules. By using X-ray absorption near-edge structure (XANES) spectroscopy and photoelectron emission microscopy (PEEM), we studied cross-sections of fresh sea urchin spicules at different stages (36h, 48h and 72h after fertilization) and observed the transition sequence of three mineral phases: hydrated ACC → dehydrated ACC → biogenic calcite. In addition, we unexpectedly found hydrated ACC nanoparticles that are surrounded by biogenic calcite. This observation indicates the dehydration from hydrated ACC to dehydrated ACC is inhibited, resulting in stabilization of hydrated ACC nanoparticles. We thought that the dehydration was inhibited by protein matrix components occluded within the biomineral, and we designed an in vitro assay to test the hypothesis. By utilizing XANES-PEEM, we found that SM50, the most abundant occluded matrix protein in sea urchin spicules, has the function to stabilize hydrated ACC in vitro.

  5. Calcination of calcium carbonate and blend therefor

    SciTech Connect

    Mallow, W.A.; Dziuk, J.J. Jr.

    1989-05-09

    This patent describes a method for the accelerated calcination of a calcium carbonate material. It comprises: heating the calcium carbonate material to a temperature and for a time sufficient to calcine the material to the degree desired while in the presence of a fused salt catalyst consisting of particles having a size above or below that of the calcium carbonate material; the catalyst comprising at least one fused salt having the formula M{sub 2}CO{sub 3}. CaCO{sub 3}-CaO-H{sub 2}O{sub {ital x}}, wherein M is an alkali metal selected from sodium or potassium and x is 0 to 1 and the salt is formed by fusing M{sub 2}CO{sub 3} and CaCO{sub 3} in a molar ratio of about 1:2 to 2:1 when the alkali metal is sodium and about 1:1 to 2:1 when the alkali metal is potassium. This patent also describes a blend adapted to be heated to form CaO. It comprises: a calcium carbonate material and a catalyst consisting of particles having a size above or below that of the calcium carbonate material; the catalyst comprising at least one fused salt having the formula M{sub 2}CO{sub 3}-CaCO{sub 3}CaO-H{sub 2}O{sub {ital x}}.

  6. Calcium carbonate polymorph control using droplet-based microfluidics.

    PubMed

    Yashina, Alexandra; Meldrum, Fiona; Demello, Andrew

    2012-06-01

    Calcium carbonate (CaCO(3)) is one of the most abundant minerals and of high importance in many areas of science including global CO(2) exchange, industrial water treatment energy storage, and the formation of shells and skeletons. Industrially, calcium carbonate is also used in the production of cement, glasses, paints, plastics, rubbers, ceramics, and steel, as well as being a key material in oil refining and iron ore purification. CaCO(3) displays a complex polymorphic behaviour which, despite numerous experiments, remains poorly characterised. In this paper, we report the use of a segmented-flow microfluidic reactor for the controlled precipitation of calcium carbonate and compare the resulting crystal properties with those obtained using both continuous flow microfluidic reactors and conventional bulk methods. Through combination of equal volumes of equimolar aqueous solutions of calcium chloride and sodium carbonate on the picoliter scale, it was possible to achieve excellent definition of both crystal size and size distribution. Furthermore, highly reproducible control over crystal polymorph could be realised, such that pure calcite, pure vaterite, or a mixture of calcite and vaterite could be precipitated depending on the reaction conditions and droplet-volumes employed. In contrast, the crystals precipitated in the continuous flow and bulk systems comprised of a mixture of calcite and vaterite and exhibited a broad distribution of sizes for all reaction conditions investigated.

  7. Calcium carbonate polymorph control using droplet-based microfluidics.

    PubMed

    Yashina, Alexandra; Meldrum, Fiona; Demello, Andrew

    2012-06-01

    Calcium carbonate (CaCO(3)) is one of the most abundant minerals and of high importance in many areas of science including global CO(2) exchange, industrial water treatment energy storage, and the formation of shells and skeletons. Industrially, calcium carbonate is also used in the production of cement, glasses, paints, plastics, rubbers, ceramics, and steel, as well as being a key material in oil refining and iron ore purification. CaCO(3) displays a complex polymorphic behaviour which, despite numerous experiments, remains poorly characterised. In this paper, we report the use of a segmented-flow microfluidic reactor for the controlled precipitation of calcium carbonate and compare the resulting crystal properties with those obtained using both continuous flow microfluidic reactors and conventional bulk methods. Through combination of equal volumes of equimolar aqueous solutions of calcium chloride and sodium carbonate on the picoliter scale, it was possible to achieve excellent definition of both crystal size and size distribution. Furthermore, highly reproducible control over crystal polymorph could be realised, such that pure calcite, pure vaterite, or a mixture of calcite and vaterite could be precipitated depending on the reaction conditions and droplet-volumes employed. In contrast, the crystals precipitated in the continuous flow and bulk systems comprised of a mixture of calcite and vaterite and exhibited a broad distribution of sizes for all reaction conditions investigated. PMID:22655005

  8. Calcination of calcium carbonate and blend therefor

    DOEpatents

    Mallow, William A.; Dziuk, Jr., Jerome J.

    1989-01-01

    A method for calcination of a calcium carbonate material comprising heating the calcium carbonate material to a temperature and for a time sufficient to calcine the material to the degree desired while in the presence of a catalyst; said catalyst comprising at least one fused salt having the formula MCO.sub.3.CaCO.sub.3.CaO.H.sub.2 O.sub.x, wherein M is an alkali metal and x is 0 to 1 and formed by fusing MCO.sub.3 and CaCO.sub.3 in a molar ratio of about 1:2 to 2:1, and a blend adapted to be heated to CaO comprising a calcium carbonate material and at least one such fused salt.

  9. Calcium carbonate phase transformations during the carbonation reaction of calcium heavy alkylbenzene sulfonate overbased nanodetergents preparation.

    PubMed

    Chen, Zhaocong; Xiao, Shan; Chen, Feng; Chen, Dongzhong; Fang, Jianglin; Zhao, Min

    2011-07-01

    The preparation and application of overbased nanodetergents with excess alkaline calcium carbonate is a good example of nanotechnology in practice. The phase transformation of calcium carbonate is of extensive concern since CaCO(3) serves both as an important industrial filling material and as the most abundant biomineral in nature. Industrially valuable overbased nanodetergents have been prepared based on calcium salts of heavy alkylbenzene sulfonate by a one-step process under ambient pressure, the carbonation reaction has been monitored by the instantaneous temperature changes and total base number (TBN). A number of analytical techniques such as TGA, DLS, SLS, TEM, FTIR, and XRD have been utilized to explore the carbonation reaction process and phase transformation mechanism of calcium carbonate. An enhanced understanding on the phase transformation of calcium carbonate involved in calcium sulfonate nanodetergents has been achieved and it has been unambiguously demonstrated that amorphous calcium carbonate (ACC) transforms into the vaterite polymorph rather than calcite, which would be of crucial importance for the preparation and quality control of lubricant additives and greases. Our results also show that a certain amount of residual Ca(OH)(2) prevents the phase transformation from ACC to crystalline polymorphs. Moreover, a vaterite nanodetergent has been prepared for the first time with low viscosity, high base number, and uniform particle size, nevertheless a notable improvement on its thermal stability is required for potential applications.

  10. Carbon material for hydrogen storage

    DOEpatents

    Bourlinos, Athanasios; Steriotis, Theodore; Stubos, Athanasios; Miller, Michael A

    2016-09-13

    The present invention relates to carbon based materials that are employed for hydrogen storage applications. The material may be described as the pyrolysis product of a molecular precursor such as a cyclic quinone compound. The pyrolysis product may then be combined with selected transition metal atoms which may be in nanoparticulate form, where the metals may be dispersed on the material surface. Such product may then provide for the reversible storage of hydrogen. The metallic nanoparticles may also be combined with a second metal as an alloy to further improve hydrogen storage performance.

  11. Calcium kinetics in glycogen storage disease type 1a.

    PubMed

    Goans, R E; Weiss, G H; Vieira, N E; Sidbury, J B; Abrams, S A; Yergey, A L

    1996-12-01

    Glycogen storage disease type 1a (Von Gierke's disease) is one of the more common glycogen storage diseases (GSD). GSD 1a patients can have severe idiopathic osteopenia, often beginning at a young age. Since calcium tracer studies offer a sensitive probe of the bone microenvironment and of calcium deposition, kinetics might be disturbed in patients with GSD 1a. Plasma dilution kinetics obtained using the stable isotope 42Ca are shown in this paper to be quite different between GSD 1a patients and age-matched controls. Comparison of kinetic parameters in these two populations is made using a new binding site model for describing calcium dynamics at the plasma-bone interface. This model describes reversible binding of calcium ions to postulated short-term and long-term sites by a retention probability density function psi (t). Using this analysis, adult GSD subjects exhibited a significant decrease (P = 0.023) in the apparent half-life of a calcium ion on the longer-term site compared with controls. The general theory of calcium tracer dilution kinetics is then discussed in terms of a new model of short-term calcium homeostasis recently proposed by Bronner and Stein [5]. PMID:8939770

  12. Phase transitions in biogenic amorphous calcium carbonate.

    PubMed

    Gong, Yutao U T; Killian, Christopher E; Olson, Ian C; Appathurai, Narayana P; Amasino, Audra L; Martin, Michael C; Holt, Liam J; Wilt, Fred H; Gilbert, P U P A

    2012-04-17

    Crystalline biominerals do not resemble faceted crystals. Current explanations for this property involve formation via amorphous phases. Using X-ray absorption near-edge structure (XANES) spectroscopy and photoelectron emission microscopy (PEEM), here we examine forming spicules in embryos of Strongylocentrotus purpuratus sea urchins, and observe a sequence of three mineral phases: hydrated amorphous calcium carbonate (ACC · H(2)O) → dehydrated amorphous calcium carbonate (ACC) → calcite. Unexpectedly, we find ACC · H(2)O-rich nanoparticles that persist after the surrounding mineral has dehydrated and crystallized. Protein matrix components occluded within the mineral must inhibit ACC · H(2)O dehydration. We devised an in vitro, also using XANES-PEEM, assay to identify spicule proteins that may play a role in stabilizing various mineral phases, and found that the most abundant occluded matrix protein in the sea urchin spicules, SM50, stabilizes ACC · H(2)O in vitro. PMID:22492931

  13. Shear response of concentrated calcium carbonate suspensions.

    PubMed

    Kugge, C; Daicic, J

    2004-03-01

    The rheology of concentrated calcium carbonate suspensions is investigated with respect to addition of solution and dispersion polymers. System materials and composition are chosen to be similar, generically, to those in use in the coating of paper. Specifically, we investigate the particle volume fraction dependence of the relative viscosity, using both capillary and steady-shear concentric cylinder measurement methods to cover a broad range of concentrations. The results are interpreted in terms of semi-empirical models, such as the Krieger-Dougherty model. Oscillatory shear measurements are also employed to investigate the viscoelastic behavior of the concentrated suspensions. The measurements indicate that a common solution polymer thickener, carboxymethyl cellulose (CMC), causes depletion flocculation of calcium carbonate suspensions.

  14. Apatite Formation from Amorphous Calcium Phosphate and Mixed Amorphous Calcium Phosphate/Amorphous Calcium Carbonate.

    PubMed

    Ibsen, Casper J S; Chernyshov, Dmitry; Birkedal, Henrik

    2016-08-22

    Crystallization from amorphous phases is an emerging pathway for making advanced materials. Biology has made use of amorphous precursor phases for eons and used them to produce structures with remarkable properties. Herein, we show how the design of the amorphous phase greatly influences the nanocrystals formed therefrom. We investigate the transformation of mixed amorphous calcium phosphate/amorphous calcium carbonate phases into bone-like nanocrystalline apatite using in situ synchrotron X-ray diffraction and IR spectroscopy. The speciation of phosphate was controlled by pH to favor HPO4 (2-) . In a carbonate free system, the reaction produces anisotropic apatite crystallites with large aspect ratios. The first formed crystallites are highly calcium deficient and hydrogen phosphate rich, consistent with thin octacalcium phosphate (OCP)-like needles. During growth, the crystallites become increasingly stoichiometric, which indicates that the crystallites grow through addition of near-stoichiometric apatite to the OCP-like initial crystals through a process that involves either crystallite fusion/aggregation or Ostwald ripening. The mixed amorphous phases were found to be more stable against phase transformations, hence, the crystallization was inhibited. The resulting crystallites were smaller and less anisotropic. This is rationalized by the idea that a local phosphate-depletion zone formed around the growing crystal until it was surrounded by amorphous calcium carbonate, which stopped the crystallization. PMID:27460160

  15. Carbon Aerogels for Hydrogen Storage

    SciTech Connect

    Baumann, T F; Worsley, M; Satcher, J H

    2008-08-11

    This effort is focused on the design of new nanostructured carbon-based materials that meet the DOE 2010 targets for on-board vehicle hydrogen storage. Carbon aerogels (CAs) are a unique class of porous materials that possess a number of desirable structural features for the storage of hydrogen, including high surface areas (over 3000 m{sup 2}/g), continuous and tunable porosities, and variable densities. In addition, the flexibility associated with CA synthesis allows for the incorporation of modifiers or catalysts into the carbon matrix in order to alter hydrogen sorption enthalpies in these materials. Since the properties of the doped CAs can be systematically modified (i.e. amount/type of dopant, surface area, porosity), novel materials can be fabricated that exhibit enhanced hydrogen storage properties. We are using this approach to design new H{sub 2} sorbent materials that can storage appreciable amounts of hydrogen at room temperature through a process known as hydrogen spillover. The spillover process involves the dissociative chemisorption of molecular hydrogen on a supported metal catalyst surface (e.g. platinum or nickel), followed by the diffusion of atomic hydrogen onto the surface of the support material. Due to the enhanced interaction between atomic hydrogen and the carbon support, hydrogen can be stored in the support material at more reasonable operating temperatures. While the spillover process has been shown to increase the reversible hydrogen storage capacities at room temperature in metal-loaded carbon nanostructures, a number of issues still exist with this approach, including slow kinetics of H{sub 2} uptake and capacities ({approx} 1.2 wt% on carbon) below the DOE targets. The ability to tailor different structural aspects of the spillover system (i.e. the size/shape of the catalyst particle, the catalyst-support interface and the support morphology) should provide valuable mechanistic information regarding the critical aspects of the

  16. Is Mg-stabilized amorphous calcium carbonate a homogeneous mixture of amorphous magnesium carbonate and amorphous calcium carbonate?

    PubMed

    Yang, Sheng-Yu; Chang, Hsun-Hui; Lin, Cang-Jie; Huang, Shing-Jong; Chan, Jerry C C

    2016-10-01

    We find two types of carbonate ions in Mg stabilized amorphous calcium carbonate (Mg-ACC), whose short-range orders are identical to those of ACC and amorphous magnesium carbonate (AMC). Mg-ACC comprises a homogeneous mixture of the nano-clusters of ACC and AMC. Their relative amount varies systematically at different pH. PMID:27524162

  17. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V. J. Fabry

    2003-10-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds or bioreactors to abate CO{sub 2} emissions from power plants.

  18. Calcium Carbonate Production by Coccolithophorid Alge in Long Term Carbon Dioxide Sequestration

    SciTech Connect

    V. J. Fabry

    2006-09-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  19. Calcium Carbonate Produced by Coccolithophorid Algae in Long Term, Carbon Dioxide Sequestration

    SciTech Connect

    V.J. Fabry

    2007-06-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO2 through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids - single-celled, marine algae that are the major global producers of calcium carbonate - to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  20. Calcium Carbonate Production by Coccolithophorid Algae in Long Term, Carbon Dioxide Sequestration

    SciTech Connect

    V. J. Fabry

    2006-06-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  1. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2002-09-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  2. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry

    2004-10-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds or bioreactors to abate CO{sub 2} emissions from power plants.

  3. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V. J. Fabry

    2005-01-24

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids ? single-celled, marine algae that are the major global producers of calcium carbonate ? to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  4. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2002-07-09

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  5. CALCIUM CARBONATE PRODUCTION BY COCCOLITHAPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V. J.Fabry

    2004-01-30

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  6. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry

    2004-04-26

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids single-celled, marine algae that are the major global producers of calcium carbonate to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  7. Calcium Carbonate Production by Coccolithophorid Algae in Long Term, Carbon Dioxide Sequestration

    SciTech Connect

    V.J. Fabry

    2005-04-29

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  8. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2003-07-15

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  9. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2001-12-15

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  10. CALCIUM CARBONATE PRODUCTION BY COCCOLITHOPHORID ALGAE IN LONG TERM, CARBON DIOXIDE SEQUESTRATION

    SciTech Connect

    V.J. Fabry, Ph.D.

    2002-04-05

    Predictions of increasing levels of anthropogenic carbon dioxide (CO{sub 2}) and the specter of global warming have intensified research efforts to identify ways to sequester carbon. A number of novel avenues of research are being considered, including bioprocessing methods to promote and accelerate biosequestration of CO{sub 2} from the environment through the growth of organisms such as coccolithophorids, which are capable of sequestering CO{sub 2} relatively permanently. Calcium and magnesium carbonates are currently the only proven, long-term storage reservoirs for carbon. Whereas organic carbon is readily oxidized and releases CO{sub 2} through microbial decomposition on land and in the sea, carbonates can sequester carbon over geologic time scales. This proposal investigates the use of coccolithophorids--single-celled, marine algae that are the major global producers of calcium carbonate--to sequester CO{sub 2} emissions from power plants. Cultivation of coccolithophorids for calcium carbonate (CaCO{sub 3}) precipitation is environmentally benign and results in a stable product with potential commercial value. Because this method of carbon sequestration does not impact natural ecosystem dynamics, it avoids controversial issues of public acceptability and legality associated with other options such as direct injection of CO{sub 2} into the sea and ocean fertilization. Consequently, cultivation of coccolithophorids could be carried out immediately and the amount of carbon sequestered as CaCO{sub 3} could be readily quantified. The significant advantages of this approach warrant its serious investigation. The major goals of the proposed research are to identify the growth conditions that will result in the maximum amount of CO{sub 2} sequestration through coccolithophorid calcite production and to evaluate the costs/benefits of using coccolithophorid cultivation ponds to abate CO{sub 2} emissions from power plants.

  11. Structural Characteristics of Synthetic Amorphous Calcium Carbonate

    SciTech Connect

    Michel, F. Marc; MacDonald, Jason; Feng, Jian; Phillips, Brian L.; Ehm, Lars; Tarabrella, Cathy; Parise, John B.; Reeder, Richard J.

    2008-08-06

    Amorphous calcium carbonate (ACC) is an important phase involved in calcification by a wide variety of invertebrate organisms and is of technological interest in the development of functional materials. Despite widespread scientific interest in this phase a full characterization of structure is lacking. This is mainly due to its metastability and difficulties in evaluating structure using conventional structure determination methods. Here we present new findings from the application of two techniques, pair distribution function analysis and nuclear magnetic resonance spectroscopy, which provide new insight to structural aspects of synthetic ACC. Several important results have emerged from this study of ACC formed in vitro using two common preparation methods: (1) ACC exhibits no structural coherence over distances > 15 {angstrom} and is truly amorphous; (2) most of the hydrogen in ACC is present as structural H{sub 2}O, about half of which undergoes restricted motion on the millisecond time scale near room temperature; (3) the short- and intermediate-range structure of ACC shows no distinct match to any known structure in the calcium carbonate system; and (4) most of the carbonate in ACC is monodentate making it distinctly different from monohydrocalcite. Although the structure of synthetic ACC is still not fully understood, the results presented provide an important baseline for future experiments evaluating biogenic ACC and samples containing certain additives that may play a role in stabilization of ACC, crystallization kinetics, and final polymorph selection.

  12. Polymorphs calcium carbonate on temperature reaction

    SciTech Connect

    Chong, Kai-Yin; Chia, Chin-Hua; Zakaria, Sarani

    2014-09-03

    Calcium carbonate (CaCO{sub 3}) has three different crystal polymorphs, which are calcite, aragonite and vaterite. In this study, effect of reaction temperature on polymorphs and crystallite structure of CaCO{sub 3} was investigated. X-ray powder diffraction (XRD), fourier transform infrared (FTIR), and variable pressure scanning electron microscope (VPSEM) were used to characterize the obtained CaCO{sub 3} particles. The obtained results showed that CaCO{sub 3} with different crystal and particle structures can be formed by controlling the temperature during the synthesis process.

  13. Clonorcis sinensis eggs are associated with calcium carbonate gallbladder stones.

    PubMed

    Qiao, Tie; Ma, Rui-hong; Luo, Zhen-liang; Yang, Liu-qing; Luo, Xiao-bing; Zheng, Pei-ming

    2014-10-01

    Calcium carbonate gallbladder stones were easily neglected because they were previously reported as a rare stone type in adults. The aim of this study was to investigate the relationship between calcium carbonate stones and Clonorchis sinensis infection. A total of 598 gallbladder stones were studied. The stone types were identified by FTIR spectroscopy. The C. sinensis eggs and DNA were detected by microscopic examination and real-time fluorescent PCR respectively. And then, some egg-positive stones were randomly selected for further SEM examination. Corresponding clinical characteristics of patients with different types of stones were also statistically analyzed. The detection rate of C. sinensis eggs in calcium carbonate stone, pigment stone, mixed stone and cholesterol stone types, as well as other stone types was 60%, 44%, 36%, 6% and 30%, respectively, which was highest in calcium carbonate stone yet lowest in cholesterol stone. A total of 182 stones were egg-positive, 67 (37%) of which were calcium carbonate stones. The C. sinensis eggs were found adherent to calcium carbonate crystals by both light microscopy and scanning electron microscopy. Patients with calcium carbonate stones were mainly male between the ages of 30 and 60, the CO2 combining power of patients with calcium carbonate stones were higher than those with cholesterol stones. Calcium carbonate gallbladder stones are not rare, the formation of which may be associated with C. sinensis infection.

  14. Calcium and Oxygen Isotopic Composition of Calcium Carbonates

    NASA Astrophysics Data System (ADS)

    Niedermayr, Andrea; Eisenhauer, Anton; Böhm, Florian; Kisakürek, Basak; Balzer, Isabelle; Immenhauser, Adrian; Jürgen Köhler, Stephan; Dietzel, Martin

    2016-04-01

    Different isotopic systems are influenced in multiple ways corresponding to the crystal structure, dehydration, deprotonation, adsorption, desorption, isotope exchange and diffusion processes. In this study we investigated the structural and kinetic effects on fractionation of stable Ca- and O-isotopes during CaCO3 precipitation. Calcite, aragonite and vaterite were precipitated using the CO2 diffusion technique[1]at a constant pH of 8.3, but various temperatures (6, 10, 25 and 40° C) and precipitation rates R (101.5 to 105 μmol h-1 m-2). The calcium isotopic fractionation between solution and vaterite is lower (Δ44/40Ca= -0.10 to -0.55 ‰) compared to calcite (-0.69 to -2.04 ‰) and aragonite (-0.91 to -1.55 ‰). In contrast the fractionation of oxygen isotopes is highest for vaterite (32.1 ‰), followed by aragonite (29.2 ‰) and calcite (27.6 ‰) at 25° C and equilibrium. The enrichment of 18O vs. 16O in all polymorphs decreases with increasing precipitation rate by around -0.7 ‰ per log(R). The calcium isotopic fractionation between calcite/ vaterite and aqueous Ca2+ increases with increasing precipitation rate by ˜0.45 ‰ per log(R) and ˜0.1 ‰ per log(R) at 25° C and 40° C, respectively. In contrast the fractionation of Ca-isotopes between aragonite and aqueous Ca2+ decreases with increasing precipitation rates. The large enrichment of 18O vs. 16O isotopes in carbonates is related to the strong bond of oxygen to the small and highly charged C4+-ion. In contrast equilibrium isotopic fractionation between solution and calcite or vaterite is nearly zero as the Ca-O bond length is similar for calcite, vaterite and the hydrated Ca. Aragonite incorporates preferentially the lighter 40Ca isotope as it has very large Ca-O bonds in comparison to the hydrated Ca. At the crystal surface the lighter 40Ca isotopes are preferentially incorporated as dehydration and diffusion of lighter isotopes are faster. Consequently, the surface becomes enriched in 40

  15. Calcium and Oxygen Isotopic Composition of Calcium Carbonates

    NASA Astrophysics Data System (ADS)

    Niedermayr, Andrea; Eisenhauer, Anton; Böhm, Florian; Kisakürek, Basak; Balzer, Isabelle; Immenhauser, Adrian; Jürgen Köhler, Stephan; Dietzel, Martin

    2016-04-01

    Different isotopic systems are influenced in multiple ways corresponding to the crystal structure, dehydration, deprotonation, adsorption, desorption, isotope exchange and diffusion processes. In this study we investigated the structural and kinetic effects on fractionation of stable Ca- and O-isotopes during CaCO3 precipitation. Calcite, aragonite and vaterite were precipitated using the CO2 diffusion technique[1]at a constant pH of 8.3, but various temperatures (6, 10, 25 and 40° C) and precipitation rates R (101.5 to 105 μmol h‑1 m‑2). The calcium isotopic fractionation between solution and vaterite is lower (Δ44/40Ca= -0.10 to -0.55 ‰) compared to calcite (-0.69 to -2.04 ‰) and aragonite (-0.91 to -1.55 ‰). In contrast the fractionation of oxygen isotopes is highest for vaterite (32.1 ‰), followed by aragonite (29.2 ‰) and calcite (27.6 ‰) at 25° C and equilibrium. The enrichment of 18O vs. 16O in all polymorphs decreases with increasing precipitation rate by around -0.7 ‰ per log(R). The calcium isotopic fractionation between calcite/ vaterite and aqueous Ca2+ increases with increasing precipitation rate by ˜0.45 ‰ per log(R) and ˜0.1 ‰ per log(R) at 25° C and 40° C, respectively. In contrast the fractionation of Ca-isotopes between aragonite and aqueous Ca2+ decreases with increasing precipitation rates. The large enrichment of 18O vs. 16O isotopes in carbonates is related to the strong bond of oxygen to the small and highly charged C4+-ion. In contrast equilibrium isotopic fractionation between solution and calcite or vaterite is nearly zero as the Ca-O bond length is similar for calcite, vaterite and the hydrated Ca. Aragonite incorporates preferentially the lighter 40Ca isotope as it has very large Ca-O bonds in comparison to the hydrated Ca. At the crystal surface the lighter 40Ca isotopes are preferentially incorporated as dehydration and diffusion of lighter isotopes are faster. Consequently, the surface becomes enriched in

  16. Calcium and calcium isotope changes during carbon cycle perturbations at the end-Permian

    NASA Astrophysics Data System (ADS)

    Komar, N.; Zeebe, R. E.

    2016-01-01

    Negative carbon and calcium isotope excursions, as well as climate shifts, took place during the most severe mass extinction event in Earth's history, the end-Permian (˜252 Ma). Investigating the connection between carbon and calcium cycles during transient carbon cycle perturbation events, such as the end-Permian, may help resolve the intricacies between the coupled calcium-carbon cycles, as well as provide a tool for constraining the causes of mass extinction. Here we identify the deficiencies of a simplified calcium model employed in several previous studies, and we demonstrate the importance of a fully coupled carbon cycle model when investigating the dynamics of carbon and calcium cycling. Simulations with a modified version of the Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir model, which includes a fully coupled carbon-calcium cycle, indicate that increased weathering rates and ocean acidification (potentially caused by Siberian Trap volcanism) are not capable of producing trends observed in the record, as previously claimed. Our model results suggest that combined effects of carbon input via Siberian Trap volcanism (12,000 Pg C), the cessation of biological carbon export, and variable calcium isotope fractionation (due to a change in the seawater carbonate ion concentration) represents a more plausible scenario. This scenario successfully reconciles δ13C and δ44Ca trends observed in the sediment record, as well as the proposed warming of >6°C.

  17. Calcium and calcium isotope changes during carbon cycle perturbations at the end-Permian

    NASA Astrophysics Data System (ADS)

    Komar, Nemanja; Zeebe, Richard

    2016-04-01

    Negative carbon and calcium isotope excursions, as well as climate shifts, took place during the most severe mass extinction event in Earth's history, the end-Permian (˜252 Ma). Investigating the connection between carbon and calcium cycles during transient carbon cycle perturbation events, such as the end-Permian, may help resolve the intricacies between the coupled calcium-carbon cycles, as well as provide a tool for constraining the causes of mass extinction. Here, we identify the deficiencies of a simplified calcium model employed in several previous studies and we demonstrate the importance of a fully coupled carbon-cycle model when investigating the dynamics of carbon and calcium cycling. Simulations with a modified version of the LOSCAR model, which includes a fully coupled carbon-calcium cycle, indicate that increased weathering rates and ocean acidification (potentially caused by Siberian Trap volcanism) are not capable of producing trends observed in the record, as previously claimed. Our model results suggest that combined effects of carbon input via Siberian Trap volcanism (12,000 Pg C), the cessation of biological carbon export, and variable calcium isotope fractionation (due to a change in the seawater carbonate ion concentration) represents a more plausible scenario. This scenario successfully reconciles δ13C and δ44Ca trends observed in the sediment record, as well as the proposed warming of >6oC.

  18. Liquid Calcium Chloride Solar Storage: Concept and Analysis

    SciTech Connect

    Quinnell, J. A.; Davidson, J. H.; Burch, J.

    2010-01-01

    Aqueous calcium chloride has a number of potential advantages as a compact and long-term solar storage medium compared to sensibly heated water. The combination of sensible and chemical binding energy of the liquid desiccant provides higher energy densities and lower thermal losses, as well as a temperature lift during discharge via an absorption heat pump. Calcium chloride is an excellent choice among desiccant materials because it is relatively inexpensive, non-toxic, and environmentally safe. This paper provides an overview of its application for solar storage and presents a novel concept for storing the liquid desiccant in a single storage vessel. The storage system uses an internal heat exchanger to add and discharge thermal energy and to help manage the mass, momentum, and energy transfer in the tank. The feasibility of the proposed concept is demonstrated via a computational fluid dynamic study of heat and mass transfer in the system over a range of Rayleigh, Lewis, Prandtl, and buoyancy ratio numbers expected in practice.

  19. Zeta potential measurement of calcium carbonate.

    PubMed

    Moulin, P; Roques, H

    2003-05-01

    The problem of scaling, which one finds in industrial heat exchangers, particularly in atmospheric coolers in nuclear power stations, depends on calcium carbonate deposits from fresh water. To better understand this phenomenon, we have examined the eventual implication of superficial electric charge of precipitated crystal nuclei. After a bibliographical review showing a fundamental divergence from already published results, this paper describes an experimental plant to measure the zeta potential in controlled conditions of thermodynamic equilibrium, oversaturation, or undersaturation of a CaCO(3)-H(2)O-CO(2) system taking into account simultaneously the three phases: gas, liquid, and solid. The zeta potential is measured by a crystalline-plug method with calcite or aragonite crystals. The potential cancels at thermodynamic equilibrium and is always negative for other conditions, in particular for oversaturation where the possibility of scaling exists. The analysis of these results suggests that the potential determining ions of the system are Ca(2+) and HCO(-)(3).

  20. Influence of calcium sources on microbially induced calcium carbonate precipitation by Bacillus sp. CR2.

    PubMed

    Achal, Varenyam; Pan, Xiangliang

    2014-05-01

    Stimulation of microbially induced calcium carbonate precipitation (MICCP) is likely to be influenced by calcium sources. In order to study such influences, we performed MICCP using Bacillus sp. CR2 in nutrient broth containing urea, supplemented with different calcium sources (calcium chloride, calcium oxide, calcium acetate and calcium nitrate). The experiment lasted 7 days, during which bacterial growth, urease activity, calcite production and pH were measured. Our results showed that calcium chloride is the better calcium source for MICCP process, since it provides higher urease activity and more calcite production. The influences of calcium sources on MICCP were further studied using Fourier transform-infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. These analyses confirmed that the precipitate formed was CaCO3 and composed of predominantly calcite crystals with a little amount of aragonite and vaterite crystals. The maximum yield of calcite precipitation was achievable with calcium chloride followed by calcium nitrate as a calcium source. The results of present study may be applicable to media preparation during efficient MICCP process.

  1. SECONDARY HYPERPARATHYROIDISM AFTER BARIATRIC SURGERY: TREATMENT IS WITH CALCIUM CARBONATE OR CALCIUM CITRATE?

    PubMed Central

    BARETTA, Giorgio Alfredo Pedroso; CAMBI, Maria Paula Carlini; RODRIGUES, Arieli Luz; MENDES, Silvana Aparecida

    2015-01-01

    Background : Bariatric surgery, especially Roux-en-Y gastric bypass, can cause serious nutritional complications arising from poor absorption of essential nutrients. Secondary hyperparathyroidism is one such complications that leads to increased parathyroid hormone levels due to a decrease in calcium and vitamin D, which may compromise bone health. Aim : To compare calcium carbonate and calcium citrate in the treatment of secondary hyperparathyroidism. Method : Patients were selected on the basis of their abnormal biochemical test and treatment was randomly done with citrate or calcium carbonate. Results : After 60 days of supplementation, biochemical tests were repeated, showing improvement in both groups. Conclusion : Supplementation with calcium (citrate or carbonate) and vitamin D is recommended after surgery for prevention of secondary hyperparathyroidism. PMID:26537273

  2. Ecological controls over global soil carbon storage

    SciTech Connect

    Schimel, D.S.

    1995-09-01

    Globally, soil carbon comprises about 2/3 of terrestrial carbon storage. Soil carbon is thus an important reservoir of carbon, but also influences the responses of ecosystems to change by controlling many aspects of nutrient cycling. While broad-scale patterns of soil carbon accumulation can be explained in terms of climatic and biome distributions, many ecological processes also influence the storage and turnover of carbon in soils. I will present a synthesis of information from field studies, model experiments and global data bases on factors controlling the turnover and storage of soil carbon. First, I will review a series of studies showing links between vegetation change (successional and invasions) and soil carbon. Then I will review model analyses of the sensitivity of soil carbon to climatic and ecological changes. Results show that soil carbon storage is broadly sensitive to climate but greatly influenced by the allocation of detritus between resistant (lignaceous and woody) and more labile forms, and that biotic changes that affect allocation, affect soil carbon substantially at regionally and perhaps global scales.

  3. Defaunation affects carbon storage in tropical forests

    PubMed Central

    Bello, Carolina; Galetti, Mauro; Pizo, Marco A.; Magnago, Luiz Fernando S.; Rocha, Mariana F.; Lima, Renato A. F.; Peres, Carlos A.; Ovaskainen, Otso; Jordano, Pedro

    2015-01-01

    Carbon storage is widely acknowledged as one of the most valuable forest ecosystem services. Deforestation, logging, fragmentation, fire, and climate change have significant effects on tropical carbon stocks; however, an elusive and yet undetected decrease in carbon storage may be due to defaunation of large seed dispersers. Many large tropical trees with sizeable contributions to carbon stock rely on large vertebrates for seed dispersal and regeneration, however many of these frugivores are threatened by hunting, illegal trade, and habitat loss. We used a large data set on tree species composition and abundance, seed, fruit, and carbon-related traits, and plant-animal interactions to estimate the loss of carbon storage capacity of tropical forests in defaunated scenarios. By simulating the local extinction of trees that depend on large frugivores in 31 Atlantic Forest communities, we found that defaunation has the potential to significantly erode carbon storage even when only a small proportion of large-seeded trees are extirpated. Although intergovernmental policies to reduce carbon emissions and reforestation programs have been mostly focused on deforestation, our results demonstrate that defaunation, and the loss of key ecological interactions, also poses a serious risk for the maintenance of tropical forest carbon storage. PMID:26824067

  4. Defaunation affects carbon storage in tropical forests.

    PubMed

    Bello, Carolina; Galetti, Mauro; Pizo, Marco A; Magnago, Luiz Fernando S; Rocha, Mariana F; Lima, Renato A F; Peres, Carlos A; Ovaskainen, Otso; Jordano, Pedro

    2015-12-01

    Carbon storage is widely acknowledged as one of the most valuable forest ecosystem services. Deforestation, logging, fragmentation, fire, and climate change have significant effects on tropical carbon stocks; however, an elusive and yet undetected decrease in carbon storage may be due to defaunation of large seed dispersers. Many large tropical trees with sizeable contributions to carbon stock rely on large vertebrates for seed dispersal and regeneration, however many of these frugivores are threatened by hunting, illegal trade, and habitat loss. We used a large data set on tree species composition and abundance, seed, fruit, and carbon-related traits, and plant-animal interactions to estimate the loss of carbon storage capacity of tropical forests in defaunated scenarios. By simulating the local extinction of trees that depend on large frugivores in 31 Atlantic Forest communities, we found that defaunation has the potential to significantly erode carbon storage even when only a small proportion of large-seeded trees are extirpated. Although intergovernmental policies to reduce carbon emissions and reforestation programs have been mostly focused on deforestation, our results demonstrate that defaunation, and the loss of key ecological interactions, also poses a serious risk for the maintenance of tropical forest carbon storage.

  5. Defaunation affects carbon storage in tropical forests.

    PubMed

    Bello, Carolina; Galetti, Mauro; Pizo, Marco A; Magnago, Luiz Fernando S; Rocha, Mariana F; Lima, Renato A F; Peres, Carlos A; Ovaskainen, Otso; Jordano, Pedro

    2015-12-01

    Carbon storage is widely acknowledged as one of the most valuable forest ecosystem services. Deforestation, logging, fragmentation, fire, and climate change have significant effects on tropical carbon stocks; however, an elusive and yet undetected decrease in carbon storage may be due to defaunation of large seed dispersers. Many large tropical trees with sizeable contributions to carbon stock rely on large vertebrates for seed dispersal and regeneration, however many of these frugivores are threatened by hunting, illegal trade, and habitat loss. We used a large data set on tree species composition and abundance, seed, fruit, and carbon-related traits, and plant-animal interactions to estimate the loss of carbon storage capacity of tropical forests in defaunated scenarios. By simulating the local extinction of trees that depend on large frugivores in 31 Atlantic Forest communities, we found that defaunation has the potential to significantly erode carbon storage even when only a small proportion of large-seeded trees are extirpated. Although intergovernmental policies to reduce carbon emissions and reforestation programs have been mostly focused on deforestation, our results demonstrate that defaunation, and the loss of key ecological interactions, also poses a serious risk for the maintenance of tropical forest carbon storage. PMID:26824067

  6. Behaviour of calcium carbonate in sea water

    USGS Publications Warehouse

    Cloud, P.E.

    1962-01-01

    Anomalies in the behaviour of calcium carbonate in natural solutions diminish when considered in context. Best values found by traditional oceanographie methods for the apparent solubility product constant K'CaCO3 in sea water at atmospheric pressure are consistent mineralogically-at 36 parts per thousand salinity and T-25??C, K'aragonlte is estimated as 1.12 ?? 10-6 and K'calcite as 0.61 ?? 10-6. At 30??C the corresponding values are 0.98 ?? 10-6 for aragonite and 0.53 ?? 10-6 for calcite. Because the K' computations do not compensate for ionic activity, however, they cannot give thermodynamically satisfactory results. It is of interest, therefore, that approximate methods and information now available permit the estimation from the same basic data of an activity product constant KCaCO3 close to that found in solutions to which Debye-Hu??ckel theory applies. Such methods indicate approximate Karagonite 7.8 ?? 10-9 for surface sea water at 29??C; Kcalcite would be proportionately lower. Field data and experimental results indicate that the mineralogy of precipitated CaCO3 depends primarily on degree of supersaturation, thus also on kinetic or biologic factors that facilitate or inhibit a high degree of supersaturation. The shallow, generally hypersaline bank waters west of Andros Island yield aragonitic sediments with O18 O16 ratios that imply precipitation mainly during the warmer months, when the combination of a high rate of evaporation, increasing salinity (and ionic strength), maximal temperatures and photosynthetic removal of CO2 result in high apparent supersaturation. The usual precipitate from solutions of low ionic strength is calcite, except where the aragonite level of supersaturation is reached as a result of diffusion phenomena (e.g. dripstones), gradual and marked evaporation, or biologic intervention. Published data also suggest the possibility of distinct chemical milieus for crystallographic variations in skeletal calcium carbonate. It appears

  7. Urea hydrolysis and calcium carbonate reaction fronts

    NASA Astrophysics Data System (ADS)

    Fox, D. T.; Redden, G. D.; Henriksen, J.; Fujita, Y.; Guo, L.; Huang, H.

    2010-12-01

    The mobility of toxic or radioactive metal contaminants in subsurface environments can be reduced by the formation of mineral precipitates that form co-precipitates with the contaminants or that isolate them from the mobile fluid phase. An engineering challenge is to control the spatial distribution of precipitation reactions with respect to: 1) the location of a contaminant, and 2) where reactants are introduced into the subsurface. One strategy being explored for immobilizing contaminants, such as Sr-90, involves stimulating mineral precipitation by forming carbonate ions and hydroxide via the in situ, microbially mediated hydrolysis of urea. A series of column experiments have been conducted to explore how the construction or design of such an in situ reactant production strategy can affect the temporal and spatial distribution of calcium carbonate precipitation, and how the distribution is coupled to changes in permeability. The columns were constructed with silica gel as the porous media. An interval midway through the column contained an adsorbed urease enzyme in order to simulate a biologically active zone. A series of influent solutions were injected to characterize hydraulic properties of the column (e.g., bromide tracer), profiles of chemical conditions and reaction products as the enzyme catalyzes urea hydrolysis (e.g., pH, ammonia, urea), and changes that occur due to CaCO3 precipitation with the introduction of a calcium+urea solutions. In one experiment, hydraulic conductivity was reduced as precipitate accumulated in a layer within the column that had a higher fraction of fine grained silica gel. Subsequent reduction of permeability and flow (for a constant head condition) resulted in displacement of the hydrolysis and precipitation reaction profiles upstream. In another experiment, which lacked the physical heterogeneity (fine grained layer), the precipitation reaction did not result in loss of permeability or flow velocity and the reaction profile

  8. Evidence for calcium carbonate at the Mars Phoenix landing site.

    PubMed

    Boynton, W V; Ming, D W; Kounaves, S P; Young, S M M; Arvidson, R E; Hecht, M H; Hoffman, J; Niles, P B; Hamara, D K; Quinn, R C; Smith, P H; Sutter, B; Catling, D C; Morris, R V

    2009-07-01

    Carbonates are generally products of aqueous processes and may hold important clues about the history of liquid water on the surface of Mars. Calcium carbonate (approximately 3 to 5 weight percent) has been identified in the soils around the Phoenix landing site by scanning calorimetry showing an endothermic transition beginning around 725 degrees C accompanied by evolution of carbon dioxide and by the ability of the soil to buffer pH against acid addition. Based on empirical kinetics, the amount of calcium carbonate is most consistent with formation in the past by the interaction of atmospheric carbon dioxide with liquid water films on particle surfaces. PMID:19574384

  9. Disordered amorphous calcium carbonate from direct precipitation

    SciTech Connect

    Farhadi Khouzani, Masoud; Chevrier, Daniel M.; Güttlein, Patricia; Hauser, Karin; Zhang, Peng; Hedin, Niklas; Gebauer, Denis

    2015-06-01

    Amorphous calcium carbonate (ACC) is known to play a prominent role in biomineralization. Different studies on the structure of biogenic ACCs have illustrated that they can have distinct short-range orders. However, the origin of so-called proto-structures in synthetic and additive-free ACCs is not well understood. In the current work, ACC has been synthesised in iso-propanolic media by direct precipitation from ionic precursors, and analysed utilising a range of different techniques. The data suggest that this additive-free type of ACC does not resemble clear proto-structural motifs relating to any crystalline polymorph. This can be explained by the undefined pH value in iso-propanolic media, and the virtually instantaneous precipitation. Altogether, this work suggests that aqueous systems and pathways involving pre-nucleation clusters are required for the generation of clear proto-structural features in ACC. Experiments on the ACC-to-crystalline transformation in solution with and without ethanol highlight that polymorph selection is under kinetic control, while the presence of ethanol can control dissolution re-crystallisation pathways.

  10. Disordered amorphous calcium carbonate from direct precipitation

    DOE PAGES

    Farhadi Khouzani, Masoud; Chevrier, Daniel M.; Güttlein, Patricia; Hauser, Karin; Zhang, Peng; Hedin, Niklas; Gebauer, Denis

    2015-06-01

    Amorphous calcium carbonate (ACC) is known to play a prominent role in biomineralization. Different studies on the structure of biogenic ACCs have illustrated that they can have distinct short-range orders. However, the origin of so-called proto-structures in synthetic and additive-free ACCs is not well understood. In the current work, ACC has been synthesised in iso-propanolic media by direct precipitation from ionic precursors, and analysed utilising a range of different techniques. The data suggest that this additive-free type of ACC does not resemble clear proto-structural motifs relating to any crystalline polymorph. This can be explained by the undefined pH value inmore » iso-propanolic media, and the virtually instantaneous precipitation. Altogether, this work suggests that aqueous systems and pathways involving pre-nucleation clusters are required for the generation of clear proto-structural features in ACC. Experiments on the ACC-to-crystalline transformation in solution with and without ethanol highlight that polymorph selection is under kinetic control, while the presence of ethanol can control dissolution re-crystallisation pathways.« less

  11. Seeded Growth Route to Noble Calcium Carbonate Nanocrystal

    PubMed Central

    Islam, Aminul; Teo, Siow Hwa; Rahman, M. Aminur; Taufiq-Yap, Yun Hin

    2015-01-01

    A solution-phase route has been considered as the most promising route to synthesize noble nanostructures. A majority of their synthesis approaches of calcium carbonate (CaCO3) are based on either using fungi or the CO2 bubbling methods. Here, we approached the preparation of nano-precipitated calcium carbonate single crystal from salmacis sphaeroides in the presence of zwitterionic or cationic biosurfactants without external source of CO2. The calcium carbonate crystals were rhombohedron structure and regularly shaped with side dimension ranging from 33–41 nm. The high degree of morphological control of CaCO3 nanocrystals suggested that surfactants are capable of strongly interacting with the CaCO3 surface and control the nucleation and growth direction of calcium carbonate nanocrystals. Finally, the mechanism of formation of nanocrystals in light of proposed routes was also discussed. PMID:26700479

  12. Seeded Growth Route to Noble Calcium Carbonate Nanocrystal.

    PubMed

    Islam, Aminul; Teo, Siow Hwa; Rahman, M Aminur; Taufiq-Yap, Yun Hin

    2015-01-01

    A solution-phase route has been considered as the most promising route to synthesize noble nanostructures. A majority of their synthesis approaches of calcium carbonate (CaCO3) are based on either using fungi or the CO2 bubbling methods. Here, we approached the preparation of nano-precipitated calcium carbonate single crystal from salmacis sphaeroides in the presence of zwitterionic or cationic biosurfactants without external source of CO2. The calcium carbonate crystals were rhombohedron structure and regularly shaped with side dimension ranging from 33-41 nm. The high degree of morphological control of CaCO3 nanocrystals suggested that surfactants are capable of strongly interacting with the CaCO3 surface and control the nucleation and growth direction of calcium carbonate nanocrystals. Finally, the mechanism of formation of nanocrystals in light of proposed routes was also discussed.

  13. Seeded Growth Route to Noble Calcium Carbonate Nanocrystal.

    PubMed

    Islam, Aminul; Teo, Siow Hwa; Rahman, M Aminur; Taufiq-Yap, Yun Hin

    2015-01-01

    A solution-phase route has been considered as the most promising route to synthesize noble nanostructures. A majority of their synthesis approaches of calcium carbonate (CaCO3) are based on either using fungi or the CO2 bubbling methods. Here, we approached the preparation of nano-precipitated calcium carbonate single crystal from salmacis sphaeroides in the presence of zwitterionic or cationic biosurfactants without external source of CO2. The calcium carbonate crystals were rhombohedron structure and regularly shaped with side dimension ranging from 33-41 nm. The high degree of morphological control of CaCO3 nanocrystals suggested that surfactants are capable of strongly interacting with the CaCO3 surface and control the nucleation and growth direction of calcium carbonate nanocrystals. Finally, the mechanism of formation of nanocrystals in light of proposed routes was also discussed. PMID:26700479

  14. Gallbladder mucin production and calcium carbonate gallstones in children.

    PubMed

    Sayers, Craig; Wyatt, Judy; Soloway, Roger D; Taylor, Donald R; Stringer, Mark D

    2007-03-01

    In contrast to adults, calcium carbonate gallstones are relatively common in children. Their pathogenesis is poorly understood. Cystic duct obstruction promotes calcium carbonate formation in bile and increases gallbladder mucin production. We tested the hypothesis that mucin producing epithelial cells would be increased in gallbladders of children with calcium carbonate gallstones. Archival gallbladder specimens from 20 consecutive children who had undergone elective cholecystectomy for cholelithiasis were examined. In each case, gallstone composition was determined by Fourier transform infrared microspectroscopy. Gallbladder specimens from six children who had undergone cholecystectomy for conditions other than cholelithiasis during the same period were used as controls. Multiple sections were examined in a blinded fashion and scored semiquantitatively for mucin production using two stains (alcian blue and periodic acid-Schiff). Increased mucin staining was observed in 50% or more epithelial cells in five gallbladder specimens from seven children with calcium carbonate stones, compared to 5 of 13 with other stone types (P = 0.17) and none of the control gallbladders (P = 0.02). Gallbladders containing calcium carbonate stones were significantly more likely than those containing other stone types or controls to contain epithelial cells with the greatest mucin content (P = 0.03). Gallbladders containing calcium carbonate stones were also more likely to show the ulcer-associated cell lineage. These results demonstrate an increase in mucin producing epithelial cells in gallbladders from children containing calcium carbonate stones. This supports the hypothesis that cystic duct obstruction leading to increased gallbladder mucin production may play a role in the development of calcium carbonate gallstones in children.

  15. Oral calcium carbonate affects calcium but not phosphorus balance in stage 3-4 chronic kidney disease.

    PubMed

    Hill, Kathleen M; Martin, Berdine R; Wastney, Meryl E; McCabe, George P; Moe, Sharon M; Weaver, Connie M; Peacock, Munro

    2013-05-01

    Patients with chronic kidney disease (CKD) are given calcium carbonate to bind dietary phosphorus, reduce phosphorus retention, and prevent negative calcium balance; however, data are limited on calcium and phosphorus balance during CKD to support this. Here, we studied eight patients with stage 3 or 4 CKD (mean estimated glomerular filtration rate 36 ml/min) who received a controlled diet with or without a calcium carbonate supplement (1500 mg/day calcium) during two 3-week balance periods in a randomized placebo-controlled cross-over design. All feces and urine were collected during weeks 2 and 3 of each balance period and fasting blood, and urine was collected at baseline and at the end of each week. Calcium kinetics were determined using oral and intravenous (45)calcium. Patients were found to be in neutral calcium and phosphorus balance while on the placebo. Calcium carbonate supplementation produced positive calcium balance, did not affect phosphorus balance, and produced only a modest reduction in urine phosphorus excretion compared with placebo. Calcium kinetics demonstrated positive net bone balance but less than overall calcium balance, suggesting soft-tissue deposition. Fasting blood and urine biochemistries of calcium and phosphate homeostasis were unaffected by calcium carbonate. Thus, the positive calcium balance produced by calcium carbonate treatment within 3 weeks cautions against its use as a phosphate binder in patients with stage 3 or 4 CKD, if these findings can be extrapolated to long-term therapy.

  16. Wyoming Carbon Capture and Storage Institute

    SciTech Connect

    Nealon, Teresa

    2014-06-30

    This report outlines the accomplishments of the Wyoming Carbon Capture and Storage (CCS) Technology Institute (WCTI), including creating a website and online course catalog, sponsoring technology transfer workshops, reaching out to interested parties via news briefs and engaging in marketing activities, i.e., advertising and participating in tradeshows. We conclude that the success of WCTI was hampered by the lack of a market. Because there were no supporting financial incentives to store carbon, the private sector had no reason to incur the extra expense of training their staff to implement carbon storage. ii

  17. Activated carbon monoliths for methane storage

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  18. Growth of nanofibrous barium carbonate on calcium carbonate seeds

    NASA Astrophysics Data System (ADS)

    Homeijer, Sara J.; Olszta, Matthew J.; Barrett, Richard A.; Gower, Laurie B.

    2008-05-01

    Fibrous barium carbonate (BaCO 3/witherite) crystals 50-100 nm in diameter and several microns in length were grown on calcium carbonate (CaCO 3) seeds at temperatures as low as 4 °C. The BaCO 3 fibers were deposited onto calcite rhombs or CaCO 3 films using the polymer-induced liquid-precursor (PILP) process, which was induced with the sodium salt of polyacrylic acid (PAA). The structure and morphology of the resultant fibers were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and polarized light microscopy (PLM). Fibers were successfully grown on calcite seeds of various morphologies, with a range of barium concentrations, and PAA molecular weight and concentration. Two categories of fibers were grown: straight and twisted. Both types of fibers displayed single-crystalline SAED diffraction patterns, but after examining high-resolution TEM lattice images, it was revealed that the fibers were in fact made up of nanocrystalline domains. We postulate that these nanocrystalline domains are well aligned due to a singular nucleation event (i.e., each fiber propagates from a single nucleation event on the seed crystal) with the nanocrystalline domains resulting from stresses caused by dehydration during crystallization of the highly hydrated precursor phase. These BaCO 3 fibers grown on calcite substrates further illustrate the robustness and non-specificity of the PILP process.

  19. Prospects for carbon capture and storage technologies

    SciTech Connect

    Soren Anderson; Richard Newell

    2003-01-15

    Carbon capture and storage (CCS) technologies remove carbon dioxide from flue gases for storage in geologic formations or the ocean. The study found that CCS is technically feasible and economically attractive within the range of carbon policies discussed domestically and internationally. Current costs are about $200 to $250 per ton of carbon, although costs are sensitive to fuel prices and other assumptions and could be reduced significantly through technical improvements. Near-term prospects favor CCS for certain industrial sources and electric power plants, with storage in depleted oil and gas reservoirs. Deep aquifers may provide an attractive longer-term storage option, whereas ocean storage poses greater technical and environmental uncertainty. Vast quantities of economically recoverable fossil fuels, sizable political obstacles to their abandonment, and inherent delay associated with developing alternative energy sources suggest that CCS should be seriously considered in the portfolio of options for addressing climate change, alongside energy efficiency and carbon-free energy. 61 refs., 5 figs., 5 tabs.

  20. Last chance for carbon capture and storage

    NASA Astrophysics Data System (ADS)

    Scott, Vivian; Gilfillan, Stuart; Markusson, Nils; Chalmers, Hannah; Haszeldine, R. Stuart

    2013-02-01

    Anthropogenic energy-related CO2 emissions are higher than ever. With new fossil-fuel power plants, growing energy-intensive industries and new sources of fossil fuels in development, further emissions increase seems inevitable. The rapid application of carbon capture and storage is a much heralded means to tackle emissions from both existing and future sources. However, despite extensive and successful research and development, progress in deploying carbon capture and storage has stalled. No fossil-fuel power plants, the greatest source of CO2 emissions, are using carbon capture and storage, and publicly supported demonstration programmes are struggling to deliver actual projects. Yet, carbon capture and storage remains a core component of national and global emissions-reduction scenarios. Governments have to either increase commitment to carbon capture and storage through much more active market support and emissions regulation, or accept its failure and recognize that continued expansion of power generation from burning fossil fuels is a severe threat to attaining objectives in mitigating climate change.

  1. Biomineralization of calcium carbonates and their engineered applications: a review

    PubMed Central

    Dhami, Navdeep K.; Reddy, M. Sudhakara; Mukherjee, Abhijit

    2013-01-01

    Microbially induced calcium carbonate precipitation (MICCP) is a naturally occurring biological process in which microbes produce inorganic materials as part of their basic metabolic activities. This technology has been widely explored and promising with potential in various technical applications. In the present review, the detailed mechanism of production of calcium carbonate biominerals by ureolytic bacteria has been discussed along with role of bacteria and the sectors where these biominerals are being used. The applications of bacterially produced carbonate biominerals for improving the durability of buildings, remediation of environment (water and soil), sequestration of atmospheric CO2 filler material in rubbers and plastics etc. are discussed. The study also sheds light on benefits of bacterial biominerals over traditional agents and also the issues that lie in the path of successful commercialization of the technology of microbially induced calcium carbonate precipitation from lab to field scale. PMID:24194735

  2. Biomineralization of calcium carbonates and their engineered applications: a review.

    PubMed

    Dhami, Navdeep K; Reddy, M Sudhakara; Mukherjee, Abhijit

    2013-01-01

    Microbially induced calcium carbonate precipitation (MICCP) is a naturally occurring biological process in which microbes produce inorganic materials as part of their basic metabolic activities. This technology has been widely explored and promising with potential in various technical applications. In the present review, the detailed mechanism of production of calcium carbonate biominerals by ureolytic bacteria has been discussed along with role of bacteria and the sectors where these biominerals are being used. The applications of bacterially produced carbonate biominerals for improving the durability of buildings, remediation of environment (water and soil), sequestration of atmospheric CO2 filler material in rubbers and plastics etc. are discussed. The study also sheds light on benefits of bacterial biominerals over traditional agents and also the issues that lie in the path of successful commercialization of the technology of microbially induced calcium carbonate precipitation from lab to field scale. PMID:24194735

  3. Correlation between calcium carbonate content and emission characteristics of incense.

    PubMed

    Yang, Chi-Ru; Lin, Ta-Chang; Chang, Feng-Hsiang

    2006-12-01

    In Taiwan and China, calcium carbonate is commonly added as a filler during incense production to lower the cost. This study has found an unexpected benefit for this practice: it reduces particulate emission. Nine types of the popular incense on the local market were chosen for this study. The calcium content in raw material incense was analyzed by inductively coupled plasma atomic emission spectrometry, followed by X-ray diffraction (XRD) spectroscopy. The correlation between the calcium content and emission characteristics of incense was investigated. The calcium content varied from 1.8 to 60 mg/g (incense burned) among those nine different types of incense. Very little calcium (< 1%) was found in natural wood or plants, which is mainly the raw material of incense. Instead, most calcium was artificially added in the form of CaCO3 during manufacturing. The combustion characteristics, including burning rate, emission factors of particulate, ash, and solid-phase polycyclic aromatic hydrocarbons (S-PAHs), varied significantly among the nine types of incense. Incense containing 2% calcium would emit 30% less S-PAHs, compared with those with little (< 0.2%) calcium. More importantly, increasing the calcium content from 0.5 to 5% by adding CaCO3 reduced the particulate emission from incense by approximately 50%.

  4. High Density Methane Storage in Nanoporous Carbon

    NASA Astrophysics Data System (ADS)

    Rash, Tyler; Dohnke, Elmar; Soo, Yuchoong; Maland, Brett; Doynov, Plamen; Lin, Yuyi; Pfeifer, Peter; Mriglobal Collaboration; All-Craft Team

    2014-03-01

    Development of low-pressure, high-capacity adsorbent based storage technology for natural gas (NG) as fuel for advanced transportation (flat-panel tank for NG vehicles) is necessary in order to address the temperature, pressure, weight, and volume constraints present in conventional storage methods (CNG & LNG.) Subcritical nitrogen adsorption experiments show that our nanoporous carbon hosts extended narrow channels which generate a high surface area and strong Van der Waals forces capable of increasing the density of NG into a high-density fluid. This improvement in storage density over compressed natural gas without an adsorbent occurs at ambient temperature and pressures ranging from 0-260 bar (3600 psi.) The temperature, pressure, and storage capacity of a 40 L flat-panel adsorbed NG tank filled with 20 kg of nanoporous carbon will be featured.

  5. Underground storage of carbon dioxide

    SciTech Connect

    Tanaka, Shoichi

    1993-12-31

    Desk studies on underground storage of CO{sub 2} were carried out from 1990 to 1991 fiscal years by two organizations under contract with New Energy and Indestrial Technology Development Organization (NEDO). One group put emphasis on application of CO{sub 2} EOR (enhanced oil recovery), and the other covered various aspects of underground storage system. CO{sub 2} EOR is a popular EOR method in U.S. and some oil countries. At present, CO{sub 2} is supplied from natural CO{sub 2} reservoirs. Possible use of CO{sub 2} derived from fixed sources of industries is a main target of the study in order to increase oil recovery and storage CO{sub 2} under ground. The feasibility study of the total system estimates capacity of storage of CO{sub 2} as around 60 Gton CO{sub 2}, if worldwide application are realized. There exist huge volumes of underground aquifers which are not utilized usually because of high salinity. The deep aquifers can contain large amount of CO{sub 2} in form of compressed state, liquefied state or solution to aquifer. A preliminary technical and economical survey on the system suggests favorable results of 320 Gton CO{sub 2} potential. Technical problems are discussed through these studies, and economical aspects are also evaluated.

  6. Ultrasound influence upon calcium carbonate precipitation on bacterial cellulose membranes.

    PubMed

    Stoica-Guzun, Anicuta; Stroescu, Marta; Jinga, Sorin; Jipa, Iuliana; Dobre, Tanase; Dobre, Loredana

    2012-07-01

    The effect of ultrasonic irradiation (40 kHz) on the calcium carbonate deposition on bacterial cellulose membranes was investigated using calcium chloride (CaCl(2)) and sodium carbonate (Na(2)CO(3)) as starting reactants. The composite materials containing bacterial cellulose-calcium carbonate were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and color measurements. The polymorphs of calcium carbonate that were deposited on bacterial cellulose membranes in the presence or in the absence of ultrasonic irradiation were calcite and vaterite. The morphology of the obtained crystals was influenced by the concentration of starting solutions and by the presence of ultrasonic irradiation. In the presence of ultrasonic irradiation the obtained crystals were bigger and in a larger variety of shapes than in the absence of ultrasounds: from cubes of calcite to spherical and flower-like vaterite particles. Bacterial cellulose could be a good matrix for obtaining different types of calcium carbonate crystals.

  7. Incorporation of Chromate into Calcium Carbonate Structure during Coprecipitation

    SciTech Connect

    Hua, Bin; Deng, Baolin; Thornton, Edward C.; Yang, J.; Amonette, James E.

    2006-09-08

    To assess treatment technologies and establish regulatory framework for chromate-contaminated site remediation, it is imperative to know the exact chromium speciation in soil matrices. In an earlier study, Thornton and Amonette (1999) reported that some chromate in the bulk particles was not accessible to gaseous reductants or solution-phase extractants, based on XANES studies. We hypothesized that part of this non-extractable chromate may reside in the structure of minerals such as calcium carbonate. To test this hypothesis, a number of calcium carbonate precipitates were prepared in the presence of various concentrations of chromate during the precipitation, which could coprecipitate chromate, or by adding chromate after the precipitation was completed. Hydrochloric acid was used to dissolve calcium carbonate and therefore extract the coprecipitated and surface attached chromate. The results showed that the coprecipitated chromate was non-extractable by hot alkaline solution or phosphate buffer, but could be solubilized by HCl in proportional to the amount of calcium carbonate dissolved. The X-ray diffraction experiments revealed that the coprecipitation of chromate with calcium carbonate had an influence on its crystal structure: the higher the chromate concentration, the greater the ratio of vaterite to calcite.

  8. A reactive force field for aqueous-calcium carbonate systems.

    PubMed

    Gale, Julian D; Raiteri, Paolo; van Duin, Adri C T

    2011-10-01

    A new reactive force field has been derived that allows the modelling of speciation in the aqueous-calcium carbonate system. Using the ReaxFF methodology, which has now been implemented in the program GULP, calcium has been simulated as a fixed charge di-cation species in both crystalline phases, such as calcite and aragonite, as well as in the solution phase. Excluding calcium from the charge equilibration process appears to have no adverse effects for the simulation of species relevant to the aqueous environment. Based on this model, the speciation of carbonic acid, bicarbonate and carbonate have been examined in microsolvated conditions, as well as bulk water. When immersed in a droplet of 98 water molecules and two hydronium ions, the carbonate ion is rapidly converted to bicarbonate, and ultimately carbonic acid, which is formed as the metastable cis-trans isomer under kinetic control. Both first principles and ReaxFF calculations exhibit the same behaviour, but the longer timescale accessible to the latter allows the diffusion of the carbonic acid to the surface of the water to be observed, where it is more stable at the interface. Calcium carbonate is also examined as ion pairs in solution for both CaCO(3)(0)((aq)) and CaHCO(3)(+)((aq)), in addition to the (1014) surface in contact with water. PMID:21850319

  9. Automatic photometric titrations of calcium and magnesium in carbonate rocks

    USGS Publications Warehouse

    Shapiro, L.; Brannock, W.W.

    1955-01-01

    Rapid nonsubjective methods have been developed for the determination of calcium and magnesium in carbonate rocks. From a single solution of the sample, calcium is titrated directly, and magnesium is titrated after a rapid removal of R2O3 and precipitation of calcium as the tungstate. A concentrated and a dilute solution of disodium ethylenediamine tetraacetate are used as titrants. The concentrated solution is added almost to the end point, then the weak solution is added in an automatic titrator to determine the end point precisely.

  10. Carbon Cycling and Storage in Mangrove Forests

    NASA Astrophysics Data System (ADS)

    Alongi, Daniel M.

    2014-01-01

    Mangroves are ecologically and economically important forests of the tropics. They are highly productive ecosystems with rates of primary production equal to those of tropical humid evergreen forests and coral reefs. Although mangroves occupy only 0.5% of the global coastal area, they contribute 10-15% (24 Tg C y-1) to coastal sediment carbon storage and export 10-11% of the particulate terrestrial carbon to the ocean. Their disproportionate contribution to carbon sequestration is now perceived as a means for conservation and restoration and a way to help ameliorate greenhouse gas emissions. Of immediate concern are potential carbon losses to deforestation (90-970 Tg C y-1) that are greater than these ecosystems' rates of carbon storage. Large reservoirs of dissolved inorganic carbon in deep soils, pumped via subsurface pathways to adjacent waterways, are a large loss of carbon, at a potential rate up to 40% of annual primary production. Patterns of carbon allocation and rates of carbon flux in mangrove forests are nearly identical to those of other tropical forests.

  11. Carbon cycling and storage in mangrove forests.

    PubMed

    Alongi, Daniel M

    2014-01-01

    Mangroves are ecologically and economically important forests of the tropics. They are highly productive ecosystems with rates of primary production equal to those of tropical humid evergreen forests and coral reefs. Although mangroves occupy only 0.5% of the global coastal area, they contribute 10-15% (24 Tg C y(-1)) to coastal sediment carbon storage and export 10-11% of the particulate terrestrial carbon to the ocean. Their disproportionate contribution to carbon sequestration is now perceived as a means for conservation and restoration and a way to help ameliorate greenhouse gas emissions. Of immediate concern are potential carbon losses to deforestation (90-970 Tg C y(-1)) that are greater than these ecosystems' rates of carbon storage. Large reservoirs of dissolved inorganic carbon in deep soils, pumped via subsurface pathways to adjacent waterways, are a large loss of carbon, at a potential rate up to 40% of annual primary production. Patterns of carbon allocation and rates of carbon flux in mangrove forests are nearly identical to those of other tropical forests. PMID:24405426

  12. Hydrogen storage on activated carbon. Final report

    SciTech Connect

    Schwarz, J.A.

    1994-11-01

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

  13. [Calcium carbonate precipitation in UASB reactors with different substrates].

    PubMed

    Yang, Shu-Cheng; He, Yan-Ling; Zhang, Peng-Xiang; Liu, Yong-Hong; Wang, Dong-Qi; Yang, Jing

    2009-03-15

    Two lab scale upflow anaerobic sludge bed (UASB) reactors were operated at an organic loading rate of COD 9 kg x (m3 x d)(-1) to treat two kinds of calcium containing wastewaters, one of which took acetic acid as substrate and for the other, glucose and soluble starch were the substrate. Both the wastewaters contained 800 mg x L(-1) Ca+. Precipitation of calcium carbonate in the reactors was observed. The results showed that the kind of substrate had great influence on calcium carbonate precipitation. In the reactor treating acetic acid containing wastewater, a maximum calcium precipitation rate of 65% was achieved and an average rate of about 25% was then maintained. In contrast, the calcium precipitation rate for the glucose and soluble starch containing wastewater was only about 7.5%. It was also found that substantial precipitation only occurred 30 days after the reactor were operated for both of the wastewaters. After 180 days of operation, the ash content of the sludge in the reactors increased from about 10% to 70% for the acetic acid containing wastewater and 30% for the other. However, the increase of ash content had no negative influence on the COD removal efficiency, which was kept at about 90% throughout the experimental period. By the SEM it was inferred that the different substrates caused the differences of the granular sludge microstructure, leading to the diversity of calcium carbonate precipitation in the two reactors.

  14. Stabilization of amorphous calcium carbonate in inorganic silica-rich environments.

    PubMed

    Kellermeier, Matthias; Melero-García, Emilio; Glaab, Fabian; Klein, Regina; Drechsler, Markus; Rachel, Reinhard; García-Ruiz, Juan Manuel; Kunz, Werner

    2010-12-22

    In biomineralization, living organisms carefully control the crystallization of calcium carbonate to create functional materials and thereby often take advantage of polymorphism by stabilizing a specific phase that is most suitable for a given demand. In particular, the lifetime of usually transient amorphous calcium carbonate (ACC) seems to be thoroughly regulated by the organic matrix, so as to use it either as an intermediate storage depot or directly as a structural element in a permanently stable state. In the present study, we show that the temporal stability of ACC can be influenced in a deliberate manner also in much simpler purely abiotic systems. To illustrate this, we have monitored the progress of calcium carbonate precipitation at high pH from solutions containing different amounts of sodium silicate. It was found that growing ACC particles provoke spontaneous polymerization of silica in their vicinity, which is proposed to result from a local decrease of pH nearby the surface. This leads to the deposition of hydrated amorphous silica layers on the ACC grains, which arrest growth and alter the size of the particles. Depending on the silica concentration, these skins have different thicknesses and exhibit distinct degrees of porosity, therefore impeding to varying extents the dissolution of ACC and energetically favored transformation to calcite. Under the given conditions, crystallization of calcium carbonate was slowed down over tunable periods or completely prevented on time scales of years, even when ACC coexisted side by side with calcite in solution.

  15. Amorphous and crystalline calcium carbonate distribution in the tergite cuticle of moulting Porcellio scaber (Isopoda, Crustacea).

    PubMed

    Neues, Frank; Hild, Sabine; Epple, Matthias; Marti, Othmar; Ziegler, Andreas

    2011-07-01

    The main mineral components of the isopod cuticle consists of crystalline magnesium calcite and amorphous calcium carbonate. During moulting isopods moult first the posterior and then the anterior half of the body. In terrestrial species calcium carbonate is subject to resorption, storage and recycling in order to retain significant fractions of the mineral during the moulting cycle. We used synchrotron X-ray powder diffraction, elemental analysis and Raman spectroscopy to quantify the ACC/calcite ratio, the mineral phase distribution and the composition within the anterior and posterior tergite cuticle during eight different stages of the moulting cycle of Porcellio scaber. The results show that most of the amorphous calcium carbonate (ACC) is resorbed from the cuticle, whereas calcite remains in the old cuticle and is shed during moulting. During premoult resorption of ACC from the posterior cuticle is accompanied by an increase within the anterior tergites, and mineralization of the new posterior cuticle by resorption of mineral from the anterior cuticle. This suggests that one reason for using ACC in cuticle mineralization is to facilitate resorption and recycling of cuticular calcium carbonate. Furthermore we show that ACC precedes the formation of calcite in distal layers of the tergite cuticle.

  16. Ion chromatography detection of fluoride in calcium carbonate.

    PubMed

    Lefler, Jamie E; Ivey, Michelle M

    2011-09-01

    Fluoride in aquatic systems is increasing due to anthropogenic pollution, but little is known about how this fluoride affects organisms that live in and around aquatic habitats. Fluoride can bioaccumulate in structures comprised of calcium carbonate, such as shells and skeletons of both freshwater and saltwater species as diverse as snails, corals, and coccolithophorid algae. In this article, ion chromatography (IC) techniques are developed to detect and quantify fluoride in a matrix of calcium carbonate. Solid samples are dissolved in hydrochloric acid, pretreated to remove the majority of the chloride ions, and then analyzed using IC. With these methods, the 3σ limit of detection is 0.2 mg of fluoride/kg of calcium carbonate. PMID:21859530

  17. Carbon nanotube materials from hydrogen storage

    SciTech Connect

    Dillon, A.C.; Bekkedahl, T.A.; Cahill, A.F.

    1995-09-01

    The lack of convenient and cost-effective hydrogen storage is a major impediment to wide scale use of hydrogen in the United States energy economy. Improvements in the energy densities of hydrogen storage systems, reductions in cost, and increased compatibility with available and forecasted systems are required before viable hydrogen energy use pathways can be established. Carbon-based hydrogen adsorption materials hold particular promise for meeting and exceeding the U.S. Department of Energy hydrogen storage energy density targets for transportation if concurrent increases in hydrogen storage capacity and carbon density can be achieved. These two goals are normally in conflict for conventional porous materials, but may be reconciled by the design and synthesis of new adsorbent materials with tailored pore size distributions and minimal macroporosity. Carbon nanotubes offer the possibility to explore new designs for adsorbents because they can be fabricated with small size distributions, and naturally tend to self-assemble by van der Waals forces. This year we report heats of adsorption for hydrogen on nanotube materials that are 2 and 3 times greater than for hydrogen on activated carbon. The hydrogen which is most strongly bound to these materials remains on the carbon surface to temperatures greater than 285 K. These results suggest that nanocapillary forces are active in stabilizing hydrogen on the surfaces of carbon nanotubes, and that optimization of the adsorbent will lead to effective storage at higher temperatures. In this paper we will also report on our activities which are targeted at understanding and optimizing the nucleation and growth of single wall nanotubes. These experiments were made possible by the development of a unique feedback control circuit which stabilized the plasma-arc during a synthesis run.

  18. Designing Microporus Carbons for Hydrogen Storage Systems

    SciTech Connect

    Alan C. Cooper

    2012-05-02

    An efficient, cost-effective hydrogen storage system is a key enabling technology for the widespread introduction of hydrogen fuel cells to the domestic marketplace. Air Products, an industry leader in hydrogen energy products and systems, recognized this need and responded to the DOE 'Grand Challenge' solicitation (DOE Solicitation DE-PS36-03GO93013) under Category 1 as an industry partner and steering committee member with the National Renewable Energy Laboratory (NREL) in their proposal for a center-of-excellence on Carbon-Based Hydrogen Storage Materials. This center was later renamed the Hydrogen Sorption Center of Excellence (HSCoE). Our proposal, entitled 'Designing Microporous Carbons for Hydrogen Storage Systems,' envisioned a highly synergistic 5-year program with NREL and other national laboratory and university partners.

  19. Carbonic acid: an important intermediate in the surface chemistry of calcium carbonate.

    PubMed

    Al-Hosney, Hashim A; Grassian, Vicki H

    2004-07-01

    Calcium carbonate is an important and ubiquitous component of biological and geochemical systems. In this study, the surface chemistry of calcium carbonate with several trace atmospheric gases including HNO3, SO2, HCOOH, and CH3COOH is investigated with infrared spectroscopy. Adsorbed carbonic acid, H2CO3, is found to be an intermediate in these reactions. In the absence of adsorbed water, carbonic acid is stable on the surface at room temperature. However, upon water adsorption, carbonic acid dissociates as indicated by the evolution of gaseous CO2 and the disappearance of infrared absorption bands associated with adsorbed carbonic acid. Thus, it is postulated that under ambient conditions, carbonic acid may be an important albeit short-lived intermediate in the surface chemistry of calcium carbonate. PMID:15225019

  20. Distribution of calcium carbonate in desert soils: A model

    SciTech Connect

    Mayer, L.; McFadden, L.D.; Harden, J.W.

    1988-04-01

    A model that describes the distribution of calcium carbonate in desert soils as a function of dust flux, time, climate, and other soil-forming factors shows which factors most strongly influence the accumulation of carbonate and can be used to evaluate carbonate-based soil age estimates or paleoclimatic reconstructions. Models for late Holocene soils have produced carbonate distributions that are very similar to those of well-dated soils in New Mexico and southern California. These results suggest that (1) present climate is a fair representation of late Holocene climate, (2) carbonate dust flux can be approximated by its Holocene rate, and (3) changes in climate and/or dust flux at the end of the Pleistocene effected profound and complex changes in soil carbonate distributions. Both higher carbonate dust flux and greater effective precipitation are required during the latest Pleistocene-early Holocene to explain carbonate distributions in latest Pleistocene soils. 21 refs., 4 figs., 1 tab.

  1. Gas storage carbon with enhanced thermal conductivity

    SciTech Connect

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

    2000-07-18

    A carbon fiber carbon matrix hybrid adsorbent monolith with enhanced thermal conductivity for storing and releasing gas through adsorption and desorption is disclosed. The heat of adsorption of the gas species being adsorbed is sufficiently large to cause hybrid monolith heating during adsorption and hybrid monolith cooling during desorption which significantly reduces the storage capacity of the hybrid monolith, or efficiency and economics of a gas separation process. The extent of this phenomenon depends, to a large extent, on the thermal conductivity of the adsorbent hybrid monolith. This invention is a hybrid version of a carbon fiber monolith, which offers significant enhancements to thermal conductivity and potential for improved gas separation and storage systems.

  2. Gas storage carbon with enhanced thermal conductivity

    DOEpatents

    Burchell, Timothy D.; Rogers, Michael Ray; Judkins, Roddie R.

    2000-01-01

    A carbon fiber carbon matrix hybrid adsorbent monolith with enhanced thermal conductivity for storing and releasing gas through adsorption and desorption is disclosed. The heat of adsorption of the gas species being adsorbed is sufficiently large to cause hybrid monolith heating during adsorption and hybrid monolith cooling during desorption which significantly reduces the storage capacity of the hybrid monolith, or efficiency and economics of a gas separation process. The extent of this phenomenon depends, to a large extent, on the thermal conductivity of the adsorbent hybrid monolith. This invention is a hybrid version of a carbon fiber monolith, which offers significant enhancements to thermal conductivity and potential for improved gas separation and storage systems.

  3. Calcium acetate versus calcium carbonate for the control of serum phosphorus in hemodialysis patients.

    PubMed

    Almirall, J; Veciana, L; Llibre, J

    1994-01-01

    Recent in vitro and in vivo studies have shown that calcium acetate (CaAC) is a more effective phosphorus binder than, among other calcium salts, calcium carbonate (CaCO3). More efficient binding allows serum phosphorus to be controlled with a lower dose; moreover, less calcium seems to be absorbed when CaAC is used. These properties could reduce the incidence of hypercalcemia; however, in clinical practice few reports have compared these two calcium salts, and results disagree. We evaluated in a 24-week prospective cross-over study the clinical efficiency of CaCO3 and CaAC in 10 selected chronic hemodialysis patients. Only 7 patients completed the study period. The patients were randomly assigned to start treatment with one of the two calcium salts; after 12 weeks they shifted to the other treatment. Serum analytical tests included weekly control of calcium, phosphorus, and alkaline phosphatase. PTH values (intact molecule) were obtained initially and at the end of every study period. The same good control of the phosphorus level (4.79 +/- 0.6 vs. 4.94 +/- 0.8 mg/dl) was obtained with CaAC (mean doses 4.1 +/- 0.3 g/day) as with CaCO3 (mean doses 4.01 +/- 0.8 g/day). The mean serum calcium levels were similar (10.36 +/- 0.5 vs. 10.20 +/- 0.5 mg/dl). The dose of elemental calcium administered was significantly less with CaAC (957 +/- 83 mg/day) than with CaCO3 (1,590 +/- 317 mg/day). However, the incidence of hypercalcemia (Ca > 11 mg/dl) was similar during the two treatment periods (13% with CaAC vs. 14% with CaCO3). Also the incidence of Ca x P products 765 was comparable (9.5 vs. 11.9%).(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Natural Carbonation of Peridotite and Applications for Carbon Storage

    NASA Astrophysics Data System (ADS)

    Streit, E.; Kelemen, P.; Matter, J.

    2009-05-01

    Natural carbonation of peridotite in the Samail Ophiolite of Oman is surprisingly rapid and could be further enhanced to provide a safe, permanent method of CO2 storage through in situ formation of carbonate minerals. Carbonate veins form by low-temperature reaction between peridotite and groundwater in a shallow weathering horizon. Reaction with peridotite drives up the pH of the water, and extensive travertine terraces form where this groundwater emerges at the surface in alkaline springs. The potential sink for CO2 in peridotite is enormous: adding 1wt% CO2 to the peridotite in Oman could consume 1/4 of all atmospheric carbon, and several peridotite bodies of comparable size exist throughout the world. Thus carbonation rate and cost, not reservoir size, are the limiting factors on the usefulness of in situ mineral carbonation of peridotite for carbon storage. The carbonate veins in Oman are much younger than previously believed, yielding average 14C ages of 28,000 years. Age data plus estimated volumes of carbonate veins and terraces suggest 10,000 to 100,000 tons per year of CO2 are consumed by these peridotite weathering reactions in Oman. This rate can be enhanced by drilling, hydraulic fracture, injecting CO2-rich fluid, and increasing reaction temperature. Drilling and hydraulic fracture can increase volume of peridotite available for reaction. Additional fracture may occur due to the solid volume increase of the carbonation reaction, and field observations suggest that such reaction-assisted fracture may be responsible for hierarchical carbonate vein networks in peridotite. Natural carbonation of peridotite in Oman occurs at low pCO2, resulting in partial carbonation of peridotite, forming magnesite and serpentine. Raising pCO2 increases carbonation efficiency, forming of magnesite + talc, or at complete carbonation, magnesite + quartz, allowing ˜30wt% CO2 to be added to the peridotite. Increasing the temperature to 185°C can improve the reaction rate by

  5. Aragonite nanorods in calcium carbonate/polymer hybrids formed through self-organization processes from amorphous calcium carbonate solution.

    PubMed

    Kajiyama, Satoshi; Nishimura, Tatsuya; Sakamoto, Takeshi; Kato, Takashi

    2014-04-24

    Nanostructured inorganic/polymer hybrid thin films comprising aragonite nanorods derived from aqueous suspensions of amorphous calcium carbonate (ACC) are prepared. For the formation of calcium carbonate (CaCO₃)/polymer hybrids, spincoated and annealed films of poly(vinyl alcohol) (PVA) that function as polymer matrices are soaked in aqueous colloidal solutions dispersing ACC stabilized by poly(acrylic acid) (PAA). In the initial stage, calcite thin films form on the surface. Subsequently, aragonite crystals start to form inside the PVA matrix that contains PVA crystallites which induce aragonite nucleation. Nanostructured hybrids composed of calcite thin films consisting of nanoparticles and assembled aragonite nanorods are formed in the matrices of PVA.

  6. [Carbon storage and carbon sink of mangrove wetland: research progress].

    PubMed

    Zhang, Li; Guo, Zhi-hua; Li, Zhi-yong

    2013-04-01

    Mangrove forest is a special wetland forest growing in the inter-tidal zone of tropical and subtropical regions, playing important roles in windbreak, promoting silt sedimentation, resisting extreme events such as cyclones and tsunamis, and protecting coastline, etc. The total area of global mangrove forests is about 152000 km2, only accounting for 0. 4% of all forest area. There are about 230 km2 mangrove forests in China. The mangrove forests in the tropics have an average carbon storage as high as 1023 Mg hm-2, and the global mangrove forests can sequestrate about 0. 18-0. 228 Pg C a-1. In addition to plant species composition, a variety of factors such as air temperature, seawater temperature and salinity, soil physical and chemical properties, atmospheric CO2 concentration, and human activities have significant effects on the carbon storage and sink ability of mangrove forests. Many approaches based onfield measurements, including allometric equations, remote sensing, and model simulation, are applied to quantify the carbon storage and sink ability of mangrove forest wetland. To study the carbon storage and sink ability of mangrove wetland can promote the further understanding of the carbon cycle of mangrove wetland and related controlling mechanisms, being of significance for the protection and rational utilization of mangrove wetland.

  7. [Carbon storage and carbon sink of mangrove wetland: research progress].

    PubMed

    Zhang, Li; Guo, Zhi-hua; Li, Zhi-yong

    2013-04-01

    Mangrove forest is a special wetland forest growing in the inter-tidal zone of tropical and subtropical regions, playing important roles in windbreak, promoting silt sedimentation, resisting extreme events such as cyclones and tsunamis, and protecting coastline, etc. The total area of global mangrove forests is about 152000 km2, only accounting for 0. 4% of all forest area. There are about 230 km2 mangrove forests in China. The mangrove forests in the tropics have an average carbon storage as high as 1023 Mg hm-2, and the global mangrove forests can sequestrate about 0. 18-0. 228 Pg C a-1. In addition to plant species composition, a variety of factors such as air temperature, seawater temperature and salinity, soil physical and chemical properties, atmospheric CO2 concentration, and human activities have significant effects on the carbon storage and sink ability of mangrove forests. Many approaches based onfield measurements, including allometric equations, remote sensing, and model simulation, are applied to quantify the carbon storage and sink ability of mangrove forest wetland. To study the carbon storage and sink ability of mangrove wetland can promote the further understanding of the carbon cycle of mangrove wetland and related controlling mechanisms, being of significance for the protection and rational utilization of mangrove wetland. PMID:23898678

  8. CALCIUM CARBONATE DISSOLUTION RATE IN LIMESTONE CONTACTORS

    EPA Science Inventory

    The rate of carbonate mineral dissolution from limestone was studied using a rotating disk apparatus and samples of limestone of varied composition. The purpose of this study was to determine the effect of limestone composition on the kinetics of carbonate mineral dissolution. Th...

  9. Calcium supplements

    MedlinePlus

    ... TYPES OF CALCIUM SUPPLEMENTS Forms of calcium include: Calcium carbonate: Over-the-counter (OTC) antacid products, such as Tums and Rolaids, contain calcium carbonate. These sources of calcium do not cost much. ...

  10. Amorphous Calcium Carbonate Based-Microparticles for Peptide Pulmonary Delivery.

    PubMed

    Tewes, Frederic; Gobbo, Oliviero L; Ehrhardt, Carsten; Healy, Anne Marie

    2016-01-20

    Amorphous calcium carbonate (ACC) is known to interact with proteins, for example, in biogenic ACC, to form stable amorphous phases. The control of amorphous/crystalline and inorganic/organic ratios in inhalable calcium carbonate microparticles may enable particle properties to be adapted to suit the requirements of dry powders for pulmonary delivery by oral inhalation. For example, an amorphous phase can immobilize and stabilize polypeptides in their native structure and amorphous and crystalline phases have different mechanical properties. Therefore, inhalable composite microparticles made of inorganic (i.e., calcium carbonate and calcium formate) and organic (i.e., hyaluronan (HA)) amorphous and crystalline phases were investigated for peptide and protein pulmonary aerosol delivery. The crystalline/amorphous ratio and polymorphic form of the inorganic component was altered by changing the microparticle drying rate and by changing the ammonium carbonate and HA initial concentration. The bioactivity of the model peptide, salmon calcitonin (sCT), coprocessed with alpha-1-antitrypsin (AAT), a model protein with peptidase inhibitor activity, was maintained during processing and the microparticles had excellent aerodynamic properties, making them suitable for pulmonary aerosol delivery. The bioavailability of sCT after aerosol delivery as sCT and AAT-loaded composite microparticles to rats was 4-times higher than that of sCT solution.

  11. Amorphous Calcium Carbonate Based-Microparticles for Peptide Pulmonary Delivery.

    PubMed

    Tewes, Frederic; Gobbo, Oliviero L; Ehrhardt, Carsten; Healy, Anne Marie

    2016-01-20

    Amorphous calcium carbonate (ACC) is known to interact with proteins, for example, in biogenic ACC, to form stable amorphous phases. The control of amorphous/crystalline and inorganic/organic ratios in inhalable calcium carbonate microparticles may enable particle properties to be adapted to suit the requirements of dry powders for pulmonary delivery by oral inhalation. For example, an amorphous phase can immobilize and stabilize polypeptides in their native structure and amorphous and crystalline phases have different mechanical properties. Therefore, inhalable composite microparticles made of inorganic (i.e., calcium carbonate and calcium formate) and organic (i.e., hyaluronan (HA)) amorphous and crystalline phases were investigated for peptide and protein pulmonary aerosol delivery. The crystalline/amorphous ratio and polymorphic form of the inorganic component was altered by changing the microparticle drying rate and by changing the ammonium carbonate and HA initial concentration. The bioactivity of the model peptide, salmon calcitonin (sCT), coprocessed with alpha-1-antitrypsin (AAT), a model protein with peptidase inhibitor activity, was maintained during processing and the microparticles had excellent aerodynamic properties, making them suitable for pulmonary aerosol delivery. The bioavailability of sCT after aerosol delivery as sCT and AAT-loaded composite microparticles to rats was 4-times higher than that of sCT solution. PMID:26692360

  12. 40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to...

  13. 40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to...

  14. 40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to...

  15. 40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to...

  16. 40 CFR 415.300 - Applicability; description of the calcium carbonate production subcategory.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... calcium carbonate production subcategory. 415.300 Section 415.300 Protection of Environment ENVIRONMENTAL... SOURCE CATEGORY Calcium Carbonate Production Subcategory § 415.300 Applicability; description of the calcium carbonate production subcategory. The provisions of this subpart are applicable to...

  17. Direct observation of completely processed calcium carbonate dust particles.

    PubMed

    Laskin, Alexander; Iedema, Martin J; Ichkovich, Aviad; Graber, Ellen R; Taraniuk, Ilya; Rudich, Yinon

    2005-01-01

    This study presents, for the first time, field evidence of complete, irreversible processing of solid calcium carbonate (calcite)-containing particles and quantitative formation of liquid calcium nitrate particles apparently as a result of heterogeneous reaction of calcium carbonate-containing mineral dust particles with gaseous nitric acid. Formation of nitrates from individual calcite and sea salt particles was followed as a function of time in aerosol samples collected at Shoresh, Israel. Morphology and compositional changes of individual particles were observed using conventional scanning electron microscopy with energy dispersive analysis of X-rays (SEM/EDX) and computer controlled SEM/EDX. Environmental scanning electron microscopy (ESEM) was utilized to determine and demonstrate the hygroscopic behavior of calcium nitrate particles found in some of the samples. Calcium nitrate particles are exceptionally hygroscopic and deliquesce even at very low relative humidity (RH) of 9-11% which is lower than typical atmospheric environments. Transformation of non-hygroscopic dry mineral dust particles into hygroscopic wet aerosol may have substantial impacts on light scattering properties, the ability to modify clouds and heterogeneous chemistry.

  18. Direct Observation of Completely Processed Calcium Carbonate Dust Particles

    SciTech Connect

    Laskin, Alexander; Iedema, Martin J.; Ichkovich, Aviad; Graber, Ellen R.; Taraniuk, Ilya; Rudich, Yinon

    2005-05-27

    This study presents, for the first time, field evidence of complete, irreversible processing of solid calcium carbonate (calcite)-containing particles and quantitative formation of liquid calcium nitrate particles apparently as a result of heterogeneous reaction of calcium carbonate-containing mineral dust particles with gaseous nitric acid. Formation of nitrates from individual calcite and sea salt particles was followed as a function of time in aerosol samples collected at Shoresh, Israel. Morphology and compositional changes of individual particles were observed using conventional scanning electron microscopy with energy dispersive analysis of X-rays (SEM/EDX) and computer controlled SEM/EDX. Environmental scanning electron microscopy (ESEM) was utilized to determine and demonstrate the hygroscopic behavior of calcium nitrate particles found in some of the samples. Calcium nitrate particles are exceptionally hygroscopic and deliquesce even at very low relative humidity (RH) of 9 -11% which is lower than typical atmospheric environments. Transformation of non-hygroscopic dry mineral dust particles into hygroscopic wet aerosol may have substantial impacts on light scattering properties, the ability to modify clouds and heterogeneous chemistry.

  19. Preparation, physical-chemical characterisation and cytocompatibility of calcium carbonate cements.

    PubMed

    Combes, C; Miao, Baoji; Bareille, Reine; Rey, Christian

    2006-03-01

    The feasibility of calcium carbonate cements involving the recrystallisation of metastable calcium carbonate varieties has been demonstrated. Calcium carbonate cement compositions presented in this paper can be prepared straightforwardly by simply mixing water (liquid phase) with two calcium carbonate phases (solid phase) which can be easily obtained by precipitation. An original cement composition was obtained by mixing amorphous calcium carbonate and vaterite with an aqueous medium. The cement set and hardened within 2h at 37 degrees C in an atmosphere saturated with water and the final composition of the cement consisted mostly of aragonite. The hardened cement was microporous and showed poor mechanical properties. Cytotoxicity tests revealed excellent cytocompatibility of calcium carbonate cement compositions. Calcium carbonates with a higher solubility than the apatite formed for most of the marketed calcium phosphate cements might be of interest to increase biomedical cement resorption rates and to favour its replacement by bone tissue.

  20. Calcium-based multi-element chemistry for grid-scale electrochemical energy storage

    PubMed Central

    Ouchi, Takanari; Kim, Hojong; Spatocco, Brian L.; Sadoway, Donald R.

    2016-01-01

    Calcium is an attractive material for the negative electrode in a rechargeable battery due to its low electronegativity (high cell voltage), double valence, earth abundance and low cost; however, the use of calcium has historically eluded researchers due to its high melting temperature, high reactivity and unfavorably high solubility in molten salts. Here we demonstrate a long-cycle-life calcium-metal-based rechargeable battery for grid-scale energy storage. By deploying a multi-cation binary electrolyte in concert with an alloyed negative electrode, calcium solubility in the electrolyte is suppressed and operating temperature is reduced. These chemical mitigation strategies also engage another element in energy storage reactions resulting in a multi-element battery. These initial results demonstrate how the synergistic effects of deploying multiple chemical mitigation strategies coupled with the relaxation of the requirement of a single itinerant ion can unlock calcium-based chemistries and produce a battery with enhanced performance. PMID:27001915

  1. Calcium-based multi-element chemistry for grid-scale electrochemical energy storage.

    PubMed

    Ouchi, Takanari; Kim, Hojong; Spatocco, Brian L; Sadoway, Donald R

    2016-01-01

    Calcium is an attractive material for the negative electrode in a rechargeable battery due to its low electronegativity (high cell voltage), double valence, earth abundance and low cost; however, the use of calcium has historically eluded researchers due to its high melting temperature, high reactivity and unfavorably high solubility in molten salts. Here we demonstrate a long-cycle-life calcium-metal-based rechargeable battery for grid-scale energy storage. By deploying a multi-cation binary electrolyte in concert with an alloyed negative electrode, calcium solubility in the electrolyte is suppressed and operating temperature is reduced. These chemical mitigation strategies also engage another element in energy storage reactions resulting in a multi-element battery. These initial results demonstrate how the synergistic effects of deploying multiple chemical mitigation strategies coupled with the relaxation of the requirement of a single itinerant ion can unlock calcium-based chemistries and produce a battery with enhanced performance.

  2. Calcium-based multi-element chemistry for grid-scale electrochemical energy storage.

    PubMed

    Ouchi, Takanari; Kim, Hojong; Spatocco, Brian L; Sadoway, Donald R

    2016-01-01

    Calcium is an attractive material for the negative electrode in a rechargeable battery due to its low electronegativity (high cell voltage), double valence, earth abundance and low cost; however, the use of calcium has historically eluded researchers due to its high melting temperature, high reactivity and unfavorably high solubility in molten salts. Here we demonstrate a long-cycle-life calcium-metal-based rechargeable battery for grid-scale energy storage. By deploying a multi-cation binary electrolyte in concert with an alloyed negative electrode, calcium solubility in the electrolyte is suppressed and operating temperature is reduced. These chemical mitigation strategies also engage another element in energy storage reactions resulting in a multi-element battery. These initial results demonstrate how the synergistic effects of deploying multiple chemical mitigation strategies coupled with the relaxation of the requirement of a single itinerant ion can unlock calcium-based chemistries and produce a battery with enhanced performance. PMID:27001915

  3. Calcium-based multi-element chemistry for grid-scale electrochemical energy storage

    NASA Astrophysics Data System (ADS)

    Ouchi, Takanari; Kim, Hojong; Spatocco, Brian L.; Sadoway, Donald R.

    2016-03-01

    Calcium is an attractive material for the negative electrode in a rechargeable battery due to its low electronegativity (high cell voltage), double valence, earth abundance and low cost; however, the use of calcium has historically eluded researchers due to its high melting temperature, high reactivity and unfavorably high solubility in molten salts. Here we demonstrate a long-cycle-life calcium-metal-based rechargeable battery for grid-scale energy storage. By deploying a multi-cation binary electrolyte in concert with an alloyed negative electrode, calcium solubility in the electrolyte is suppressed and operating temperature is reduced. These chemical mitigation strategies also engage another element in energy storage reactions resulting in a multi-element battery. These initial results demonstrate how the synergistic effects of deploying multiple chemical mitigation strategies coupled with the relaxation of the requirement of a single itinerant ion can unlock calcium-based chemistries and produce a battery with enhanced performance.

  4. Accelerated carbonation of Friedel's salt in calcium aluminate cement paste

    SciTech Connect

    Goni, S.; Guerrero, A

    2003-01-01

    The stability of Friedel's salt with respect to carbonation has been studied in calcium aluminate cement (CAC) pastes containing NaCl (3% of Cl{sup -} by weight of cement). Carbonation was carried out on a powdered sample in flowing 5% CO{sub 2} gas at 65% relative humidity to accelerate the process. At an intermediate carbonation step, a part of the sample was washed and dried up to 10 cycles to simulate a dynamic leaching attack. The two processes were followed by means of X-ray diffraction (XRD), pH and Cl{sup -} analyses in the simulated pore solution.

  5. 46 CFR 76.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 3 2011-10-01 2011-10-01 false Carbon dioxide storage. 76.15-20 Section 76.15-20... EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 76.15-20 Carbon dioxide storage. (a) Except as... than 300 pounds of carbon dioxide, may have the cylinders located within the space protected. If...

  6. 46 CFR 76.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 3 2012-10-01 2012-10-01 false Carbon dioxide storage. 76.15-20 Section 76.15-20... EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 76.15-20 Carbon dioxide storage. (a) Except as... than 300 pounds of carbon dioxide, may have the cylinders located within the space protected. If...

  7. 46 CFR 193.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Carbon dioxide storage. 193.15-20 Section 193.15-20... PROTECTION EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 193.15-20 Carbon dioxide storage. (a...), consisting of not more than 300 pounds of carbon dioxide, may have cylinders located within the...

  8. 46 CFR 193.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Carbon dioxide storage. 193.15-20 Section 193.15-20... PROTECTION EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 193.15-20 Carbon dioxide storage. (a...), consisting of not more than 300 pounds of carbon dioxide, may have cylinders located within the...

  9. 46 CFR 95.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Carbon dioxide storage. 95.15-20 Section 95.15-20... PROTECTION EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 95.15-20 Carbon dioxide storage. (a... of not more than 300 pounds of carbon dioxide, may have the cylinders located within the...

  10. 46 CFR 95.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Carbon dioxide storage. 95.15-20 Section 95.15-20... PROTECTION EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 95.15-20 Carbon dioxide storage. (a... of not more than 300 pounds of carbon dioxide, may have the cylinders located within the...

  11. 46 CFR 76.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Carbon dioxide storage. 76.15-20 Section 76.15-20... EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 76.15-20 Carbon dioxide storage. (a) Except as... than 300 pounds of carbon dioxide, may have the cylinders located within the space protected. If...

  12. 46 CFR 95.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Carbon dioxide storage. 95.15-20 Section 95.15-20... PROTECTION EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 95.15-20 Carbon dioxide storage. (a... of not more than 300 pounds of carbon dioxide, may have the cylinders located within the...

  13. 46 CFR 95.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Carbon dioxide storage. 95.15-20 Section 95.15-20... PROTECTION EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 95.15-20 Carbon dioxide storage. (a... of not more than 300 pounds of carbon dioxide, may have the cylinders located within the...

  14. 46 CFR 76.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 3 2014-10-01 2014-10-01 false Carbon dioxide storage. 76.15-20 Section 76.15-20... EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 76.15-20 Carbon dioxide storage. (a) Except as... than 300 pounds of carbon dioxide, may have the cylinders located within the space protected. If...

  15. 46 CFR 95.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Carbon dioxide storage. 95.15-20 Section 95.15-20... PROTECTION EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 95.15-20 Carbon dioxide storage. (a... of not more than 300 pounds of carbon dioxide, may have the cylinders located within the...

  16. 46 CFR 76.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 3 2013-10-01 2013-10-01 false Carbon dioxide storage. 76.15-20 Section 76.15-20... EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 76.15-20 Carbon dioxide storage. (a) Except as... than 300 pounds of carbon dioxide, may have the cylinders located within the space protected. If...

  17. Functional Carbon Materials for Electrochemical Energy Storage

    NASA Astrophysics Data System (ADS)

    Zhou, Huihui

    The ability to harvest and convert solar energy has been associated with the evolution of human civilization. The increasing consumption of fossil fuels since the industrial revolution, however, has brought to concerns in ecological deterioration and depletion of the fossil fuels. Facing these challenges, humankind is forced to seek for clean, sustainable and renewable energy resources, such as biofuels, hydraulic power, wind power, geothermal energy and other kinds of alternative energies. However, most alternative energy sources, generally in the form of electrical energy, could not be made available on a continuous basis. It is, therefore, essential to store such energy into chemical energy, which are portable and various applications. In this context, electrochemical energy-storage devices hold great promises towards this goal. The most common electrochemical energy-storage devices are electrochemical capacitors (ECs, also called supercapacitors) and batteries. In comparison to batteries, ECs posses high power density, high efficiency, long cycling life and low cost. ECs commonly utilize carbon as both (symmetric) or one of the electrodes (asymmetric), of which their performance is generally limited by the capacitance of the carbon electrodes. Therefore, developing better carbon materials with high energy density has been emerging as one the most essential challenges in the field. The primary objective of this dissertation is to design and synthesize functional carbon materials with high energy density at both aqueous and organic electrolyte systems. The energy density (E) of ECs are governed by E = CV 2/2, where C is the total capacitance and V is the voltage of the devices. Carbon electrodes with high capacitance and high working voltage should lead to high energy density. In the first part of this thesis, a new class of nanoporous carbons were synthesized for symmetric supercapacitors using aqueous Li2SO4 as the electrolyte. A unique precursor was adopted to

  18. Calcium Isotope Signature of Amorphous Calcium Carbonate: A Probe of Crystallization Pathway? (Invited)

    NASA Astrophysics Data System (ADS)

    Gagnon, A. C.; Depaolo, D. J.; Deyoreo, J. J.

    2010-12-01

    Stable isotope fractionation is sensitive to the energy landscape of nucleation and growth. Thus isotope ratios represent a promising tool to understand the chemical mechanisms controlling precipitation in geological systems. To realize this potential we must (1) determine the isotopic fractionation associated with different growth pathways, (2) use these isotopic constraints to test nucleation or growth mechanism, and (3) compare these signatures to natural isotopic variability. The first two goals can be explored by laboratory precipitation under controlled conditions. Through inorganic synthesis of amorphous calcium carbonate (ACC), we quantify the impact of an important amorphous precursor phase on calcium isotope ratios. Synthetic ACC was first characterized spectroscopically, then calcium isotope analysis was conducted using a double-spike method on a thermal ionization mass spectrometer. Experiments spanning a range of oversaturations and temperatures show that ACC is consistently less fractionated than CaCO3 precipitated as crystalline calcite. These data suggest the rate-limiting step that controls calcium incorporation is different between ACC and direct precipitation of calcite. Furthermore, different isotopic signatures between ACC and calcite appear to represent a useful proxy for crystallization pathway. To further explore this possibility, we plan to measure the calcium isotope composition of several biominerals where an ACC precursor phase has been identified. It is hoped that our investigation will lead to both improved identification of the ACC pathway and a better understanding of the general rules that control CaCO3 crystal growth and composition.

  19. [The crystal behavior of calcium carbonate in water-soluable chitin].

    PubMed

    Song, Rui; He, Ling-Hao; Xie, Qiao-Li; Yang, Hao

    2007-07-01

    Based on the basic principles of biominerlization, the paper analyses calcium carbonate crystallization in waterable chitin solution under the control of chitin, using chitin as the matrix; and analyses the effect on crystals by varying temperature or pH of the system. The obtained calcium carbonate was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electronic microscopy(SEM) and X ray powder diffraction (XRD). As a result, it was found that crystals were different formed in purity water; and the obtained crystals are different in different concentration chitin solution. Calcium carbonate has effect on chitin during the calcium carbonate formation process, so there is the interaction between chitin and calcium carbonate.

  20. Carbon nanotube materials for hydrogen storage

    SciTech Connect

    Dillon, A.C.; Jones, K.M.; Heben, M.J.

    1996-10-01

    Hydrogen burns pollution-free and may be produced from renewable energy resources. It is therefore an ideal candidate to replace fossil fuels as an energy carrier. However, the lack of a convenient and cost-effective hydrogen storage system greatly impedes the wide-scale use of hydrogen in both domestic and international markets. Although several hydrogen storage options exist, no approach satisfies all of the efficiency, size, weight, cost and safety requirements for transportation or utility use. A material consisting exclusively of micropores with molecular dimensions could simultaneously meet all of the requirements for transportation use if the interaction energy for hydrogen was sufficiently strong to cause hydrogen adsorption at ambient temperatures. Small diameter ({approx}1 mm) carbon single-wall nanotubes (SWNTs) are elongated micropores of molecular dimensions, and materials composed predominantly of SWNTs may prove to be the ideal adsorbent for ambient temperature storage of hydrogen. Last year the authors reported that hydrogen could be adsorbed on arc-generated soots containing 12{Angstrom} diameter nanotubes at temperatures in excess of 285K. In this past year they have learned that such adsorption does not occur on activated carbon materials, and that the cobalt nanoparticles present in their arc-generated soots are not responsible for the hydrogen which is stable at 285 K. These results indicate that enhanced adsorption forces within the internal cavities of the SWNTs are active in stabilizing hydrogen at elevated temperatures. This enhanced stability could lead to effective hydrogen storage under ambient temperature conditions. In the past year the authors have also demonstrated that single-wall carbon nanotubes in arc-generated soots may be selectively opened by oxidation in H{sub 2}O resulting in improved hydrogen adsorption, and they have estimated experimentally that the amount of hydrogen stored is {approximately}10% of the nanotube weight.

  1. Precipitation diagram of calcium carbonate polymorphs: its construction and significance

    NASA Astrophysics Data System (ADS)

    Kawano, Jun; Shimobayashi, Norimasa; Miyake, Akira; Kitamura, Masao

    2009-10-01

    In order to interpret the formation mechanism of calcium carbonate polymorphs, we propose and construct a new 'precipitation diagram', which has two variables: the driving force for nucleation and temperature. The precipitation experiments were carried out by mixing calcium chloride and sodium carbonate aqueous solutions. As a result, a calcite-vaterite co-precipitation zone, a vaterite precipitation zone, a vaterite-aragonite co-precipitation zone and an aragonite precipitation zone can be defined. Theoretical considerations suggest that the steady state nucleation theory can explain well the appearance of these four zones, and the first-order importance of the temperature dependency of surface free energy in the nucleation of aragonite. Furthermore, the addition of an impurity will likely result in the change of these energies, and this precipitation diagram gives a new basis for interpreting the nature of the polymorphs precipitated in both inorganic and biological environments.

  2. Terrestrial carbon storage dynamics: Chasing a moving target

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Shi, Z.; Jiang, L.; Xia, J.; Wang, Y.; Kc, M.; Liang, J.; Lu, X.; Niu, S.; Ahlström, A.; Hararuk, O.; Hastings, A.; Hoffman, F. M.; Medlyn, B. E.; Rasmussen, M.; Smith, M. J.; Todd-Brown, K. E.; Wang, Y.

    2015-12-01

    Terrestrial ecosystems have been estimated to absorb roughly 30% of anthropogenic CO2 emissions. Past studies have identified myriad drivers of terrestrial carbon storage changes, such as fire, climate change, and land use changes. Those drivers influence the carbon storage change via diverse mechanisms, which have not been unified into a general theory so as to identify what control the direction and rate of terrestrial carbon storage dynamics. Here we propose a theoretical framework to quantitatively determine the response of terrestrial carbon storage to different exogenous drivers. With a combination of conceptual reasoning, mathematical analysis, and numeric experiments, we demonstrated that the maximal capacity of an ecosystem to store carbon is time-dependent and equals carbon input (i.e., net primary production, NPP) multiplying by residence time. The capacity is a moving target toward which carbon storage approaches (i.e., the direction of carbon storage change) but usually does not attain. The difference between the capacity and the carbon storage at a given time t is the unrealized carbon storage potential. The rate of the storage change is proportional to the magnitude of the unrealized potential. We also demonstrated that a parameter space of NPP, residence time, and carbon storage potential can well characterize carbon storage dynamics quantified at six sites ranging from tropical forests to tundra and simulated by two versions (carbon-only and coupled carbon-nitrogen) of the Australian Community Atmosphere-Biosphere Land Ecosystem (CABLE) Model under three climate change scenarios (CO2 rising only, climate warming only, and RCP8.5). Overall this study reveals the unified mechanism unerlying terrestrial carbon storage dynamics to guide transient traceability analysis of global land models and synthesis of empirical studies.

  3. [Characteristics of carbon storage of Inner Mongolia forests: a review].

    PubMed

    Yang, Hao; Hu, Zhong-Min; Zhang, Lei-Ming; Li, Sheng-Gong

    2014-11-01

    Forests in Inner Mongolia account for an important part of the forests in China in terms of their large area and high living standing volume. This study reported carbon storage, carbon density, carbon sequestration rate and carbon sequestration potential of forest ecosystems in Inner Mongolia using the biomass carbon data from the related literature. Through analyzing the data of forest inventory and the generalized allometric equations between volume and biomass, previous studies had reported that biomass carbon storage of the forests in Inner Mongolia was about 920 Tg C, which was 12 percent of the national forest carbon storage, the annual average growth rate was about 1.4%, and the average of carbon density was about 43 t · hm(-2). Carbon storage and carbon density showed an increasing trend over time. Coniferous and broad-leaved mixed forest, Pinus sylvestris var. mongolica forest and Betula platyphylla forest had higher carbon sequestration capacities. Carbon storage was reduced due to human activities such as thinning and clear cutting. There were few studies on carbon storage of the forests in Inner Mongolia with focus on the soil, showing that the soil car- bon density increased with the stand age. Study on the carbon sequestration potential of forest ecosystems was still less. Further study was required to examine dynamics of carbon storage in forest ecosystems in Inner Mongolia, i. e., to assess carbon storage in the forest soils together with biomass carbon storage, to compute biomass carbon content of species organs as 45% in the allometric equations, to build more species-specific and site-specific allometric equations including root biomass for different dominant species, and to take into account the effects of climate change on carbon sequestration rate and carbon sequestration potential.

  4. Polymorph-selective crystallization of calcium carbonate inspired by biomineralization

    NASA Astrophysics Data System (ADS)

    Kim, Il Won

    This dissertation primarily examines bioinspired mineralization, focusing on the polymorph-selective crystallization of calcium carbonate. (1) The effect of epitaxy on the polymorphic control of calcium carbonate was studied with aragonite-type inorganic substrates. The critical epitaxial mismatch for aragonite growth, when conditions disfavor aragonite, seems to be less than 7.1%. Larger epitaxial strain appeared to prohibit aragonite formation even though the substrates had the same crystal structure. The epitaxy required for aragonite nucleation seems to be more precise than that often suggested for biological systems. (2) Polymers of different aqueous-solution properties were tested to observe the effect on the crystallization of calcium carbonate. Near exclusive formation of aragonite was attained through the inhibition of more stable calcite with poly(vinyl alcohol). The contributing characteristics of poly(vinyl alcohol) seemed to be its ability to hydrogen bond and its tendency to adsorb non-specifically onto solid surfaces. Similar inhibition activity is suggested for various biomacromolecules involved in biogenic aragonite formation of mollusks, with the biomacromolecules acting in the same way as poly(vinyl alcohol). (3) Polymer surfaces imprinted by aragonite-type crystals (strontium carbonate) were studied as substrates for the crystallization of calcium carbonate. Only calcite formed under vaterite-, aragonite-, and calcite-favorable conditions. This result seemed to arise from the nature of functional groups, rather than from the molecular structure of the imprint. Interaction between the functional groups and calcium carbonate is suggested to have enhanced the crystallization rate, resulting in the rapid formation of the thermodynamically stable calcite irrespective of the bulk crystallization conditions. (4) A catechol-based monomer was synthesized in the course of developing a dental adhesive, which mimics the functionalities of mussel adhesive

  5. Calcium carbonate scale control, effect of material and inhibitors.

    PubMed

    Macadam, J; Parsons, S A

    2004-01-01

    This paper focuses on developing a reproducible method for reducing calcium carbonate scale formation on heated surfaces where scaling can cause serious problems. It is known that calcium carbonate precipitation is sensitive to impurity ions, such as iron and zinc, even at trace concentration levels. In this paper two sets of experiments are reported. The first experiments were undertaken to investigate the effect of zinc, copper and iron dosing on CaCO3 nucleation and precipitation. Results from the experiments showed that the most effective inhibitor of CaCO3 precipitation was zinc and the effect was linked to dose levels and temperature. Copper and iron had little effect on precipitation in the dose range investigated. The second trial was undertaken to translate the precipitation data to scale formation. These tests were undertaken at 70 degrees C. 5 mg x L(-1) zinc dose reduced the scale formation by 35%. The effect of iron on calcium carbonate scaling rate was not significant. The physical nature of the material on which the scale is formed also influences the scaling. The scaling experiment was also used to investigate the effect of different surface material (stainless steel, copper and aluminium) on CaCO3 scale formation. Copper surface scaled the most.

  6. Synthesis of nano precipitated calcium carbonate by using a carbonation process through a closed loop reactor

    NASA Astrophysics Data System (ADS)

    Thriveni, Thenepalli; Ahn, Ji Whan; Ramakrishna, Chilakala; Ahn, Young Jun; Han, Choon

    2016-01-01

    Nano calcium carbonate particles have a wide range of industrial applications due to their beneficial properties such as high porosity and high surface area to volume ratio and due to their strengthening the mechanical properties of plastics and paper. Consequently, significant research has been done to deliver a new approach for the synthesis of precipitated nano calcium carbonate by using a carbonation process through a closed loop reactor. Both the experimental and the instrumental parameters, i.e. the CO2 flow rate, the concentration of the starting materials (Ca(OH)2 and CaO), the pH, the orifice diameter, etc., were investigated. The carbonation efficiency was increased due to the diffusion process involved in the loop reactor. The particle size was affected by the CO2 flow rate, reaction time, and orifice diameter. Finally, precipitated nano calcite calcium carbonate (50 to 100 nm) was synthesized by optimizing all the experimental and the instrumental parameters. The synthesized precipitated nano calcium carbonate was characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. This study has proved that the carbonation efficiency can be enhanced for a short time by using a loop reactor and that the carbonation process was more energy efficient and cost effective than other conventional methods.

  7. Effect of some organic solvent-water mixtures composition on precipitated calcium carbonate in carbonation process

    NASA Astrophysics Data System (ADS)

    Konopacka-Łyskawa, Donata; Kościelska, Barbara; Karczewski, Jakub

    2015-05-01

    Precipitated calcium carbonate particles were obtained during carbonation of calcium hydroxide slurry with carbon dioxide. Aqueous solutions of isopropyl alcohol, n-butanol and glycerol were used as solvents. Concentration of organic additives in the reactive mixture was from 0% to 20% (vol). Precipitation process were performed in a stirred tank reactor equipped with gas distributor. Multimodal courses of particles size distribution were determined for produced CaCO3 particles. Calcium carbonate as calcite was precipitated in all experiments. The mean Sauter diameter of CaCO3 particles decreased when the concentration of all used organic additives increased. The amount of small particle fraction in the product increased with the increasing concentration of organic solvents. Similar physical properties of used liquid phase resulted in the similar characteristics of obtained particles.

  8. Adsorbed natural gas storage with activated carbon

    SciTech Connect

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

    1996-12-31

    Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

  9. Carbon adsorption system protects LPG storage sphere

    SciTech Connect

    Gothenquist, C.A.; Rooker, K.M.

    1996-07-01

    Chevron U.S.A. Products Co. installed a carbon adsorption system to protect an LPG storage sphere at its refinery in Richmond, Calif. Vessel damage can result when amine contamination leads to emulsion formation and consequent amine carry-over, thus promoting wet-H{sub 2}S cracking. In Chevron`s No. 5 H{sub 2}S recovery plant, a mixture of butane and propane containing H{sub 2}S is contacted with diethanolamine (DEA) in a liquid-liquid absorber. The absorber is a countercurrent contactor with three packed beds. Because the sweetening system did not include a carbon adsorption unit for amine purification, contaminants were building up in the DEA. The contaminants comprised: treatment chemicals, hydrocarbons, foam inhibitors, and amine degradation products. The paper describes the solution to this problem.

  10. Cogrinding significance for calcium carbonate-calcium phosphate mixed cement. II. Effect on cement properties.

    PubMed

    Tadier, Solène; Bolay, Nadine Le; Fullana, Sophie Girod; Cazalbou, Sophie; Charvillat, Cédric; Labarrère, Michel; Boitel, Daniel; Rey, Christian; Combes, Christèle

    2011-11-01

    In the present study, we aim to evaluate the contribution of the cogrinding process in controlling calcium carbonate-dicalcium phosphate dihydrate cement properties. We set a method designed to evaluate phase separation, usually occurring during paste extrusion, which is quantitative, reliable, and discriminating and points out the determining role of cogrinding to limit filter-pressing. We show that solid-phase cogrinding leads to synergistic positive effects on cement injectability, mechanical properties, and radio-opacity. It allows maintaining a low (<0.4 kg) and constant load during the extrusion of paste, and the paste's composition remains constant and close to that of the initial paste. Analogous behavior was observed when adding a third component into the solid phase, especially SrCO(3) as a contrasting agent. Moreover, the cement's mechanical properties can be enhanced by lowering the L/S ratio because of the lower plastic limit. Finally, unloaded or Sr-loaded cements show uniform and increased optical density because of the enhanced homogeneity of dry component distribution. Interestingly, this study reveals that cogrinding improves and controls essential cement properties and involves processing parameters that could be easily scaled up. This constitutes a decisive advantage for the development of calcium carbonate-calcium phosphate mixed cements and, more generally, of injectable multicomponent bone cements that meet a surgeon's requirements. PMID:21953727

  11. Magnesium and calcium in carbonate bedrock and groundwaters, Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Crowther, J.

    Groundwaters draining Kuala Lumpur Limestone, Kinta Limestone and limestones of the Setul Formation were monitored over a 1 yr period. The closeness of the mean Mg:Ca + Mg ratios of the groundwaters (12.8%) and bedrock (13.3%) indicates calcium and magnesium dissolution to be broadly congruent. Ratios < 2.5and> 35% are much less common in groundwaters than in bedrock because of: (i) heterogeneity in bedrock mineralogy within groundwater catchments; (ii) differential solubilities of calcium and magnesium in calcites, high magnesium calcites and dolomites; and (iii) preferential precipitation of calcium in secondary carbonate deposits. In groundwaters with variable discharges, Mg:Ca + Mg correlates negatively with discharge, as calcium deposition per unit volume of water diminishes at higher flows. Use of groundwater survey data to locate areas of dolomitization and make specific inferences about the mineralogy of limestone formations is discussed, and estimates of net chemical denudation rates (range, 56.6-70.9m 3/km 2/yr) are presented.

  12. Proteomic analysis of a rare urinary stone composed of calcium carbonate and calcium oxalate dihydrate: a case report.

    PubMed

    Kaneko, Kiyoko; Matsuta, Yosuke; Moriyama, Manabu; Yasuda, Makoto; Chishima, Noriharu; Yamaoka, Noriko; Fukuuchi, Tomoko; Miyazawa, Katsuhito; Suzuki, Koji

    2014-03-01

    The objective of the present study was to investigate the matrix protein of a rare urinary stone that contained calcium carbonate. A urinary stone was extracted from a 34-year-old male patient with metabolic alkalosis. After X-ray diffractometry and infrared analysis of the stone, proteomic analysis was carried out. The resulting mass spectra were evaluated with protein search software, and matrix proteins were identified. X-ray diffraction and infrared analysis confirmed that the stone contained calcium carbonate and calcium oxalate dihydrate. Of the identified 53 proteins, 24 have not been previously reported from calcium oxalate- or calcium phosphate-containing stones. The protease inhibitors and several proteins related to cell adhesion or the cytoskeleton were identified for the first time. We analyzed in detail a rare urinary stone composed of calcium carbonate and calcium oxalate dihydrate. Considering the formation of a calcium carbonate stone, the new identified proteins should play an important role on the urolithiasis process in alkaline condition.

  13. Fractional absorption of active absorbable algal calcium (AAACa) and calcium carbonate measured by a dual stable-isotope method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With the use of stable isotopes, this study aimed to compare the bioavailability of active absorbable algal calcium (AAACa), obtained from oyster shell powder heated to a high temperature, with an additional heated seaweed component (Heated Algal Ingredient, HAI), with that of calcium carbonate. In ...

  14. Modification of nanostructured calcium carbonate for efficient gene delivery.

    PubMed

    Zhao, Dong; Wang, Chao-Qun; Zhuo, Ren-Xi; Cheng, Si-Xue

    2014-06-01

    In this study, a facile method to modify nanostructured calcium carbonate (CaCO3) gene delivery systems by adding calcium phosphate (CaP) component was developed. CaCO3/CaP/DNA nanoparticles were prepared by the co-precipitation of Ca(2+) ions with plasmid DNA in the presence of carbonate and phosphate ions. For comparison, CaCO3/DNA nanoparticles and CaP/DNA co-precipitates were also prepared. The effects of carbonate ion/phosphate ion (CO3(2-)/PO4(3-)) ratio on the particle size and gene delivery efficiency were investigated. With an appropriate CO3(2-)/PO4(3-) ratio, the co-existence of carbonate and phosphate ions could control the size of co-precipitates effectively, and CaCO3/CaP/DNA nanoparticles with a decreased size and improved stability could be obtained. The in vitro gene transfections mediated by different nanoparticles in 293T cells and HeLa cells were carried out, using pGL3-Luc as a reporter plasmid. The gene transfection efficiency of CaCO3/CaP/DNA nanoparticles could be significantly improved as compared with CaCO3/DNA nanoparticles and CaP/DNA co-precipitates. The confocal microscopy study indicated that the cellular uptake and nuclear localization of CaCO3/CaP/DNA nanoparticles were significantly enhanced as compared with unmodified CaCO3/DNA nanoparticles.

  15. Precipitation of calcium carbonate and calcium phosphate under diffusion controlled mixing

    SciTech Connect

    Tsigabu Gebrehiwet; James R. Henriksen; Luanjing Guo; Don T. Fox; Hai Huang; Lee Tu; Yoshiko Fujita; Robert W. Smith; George Redden

    2014-07-01

    Multi-component mineral precipitation in porous, subsurface environments is challenging to simulate or engineer when in situ reactant mixing is controlled by diffusion. In contrast to well-mixed systems, the conditions that favor mineral precipitation in porous media are distributed along chemical gradients, which evolve spatially due to concurrent mineral precipitation and modification of solute transport in the media. The resulting physical and chemical characteristics of a mixing/precipitation zone are a consequence of coupling between transport and chemical processes, and the distinctive properties of individual chemical systems. We examined the spatial distribution of precipitates formed in “double diffusion” columns for two chemical systems, calcium carbonate and calcium phosphate. Polyacrylamide hydrogel was used as a low permeability, high porosity medium to maximize diffusive mixing and minimize pressure- and density-driven flow between reactant solutions. In the calcium phosphate system, multiple, visually dense and narrow bands of precipitates were observed that were reminiscent of previously reported Liesegang patterns. In the calcium carbonate system, wider precipitation zones characterized by more sparse distributions of precipitates and a more open channel structure were observed. In both cases, formation of precipitates inhibited, but did not necessarily eliminate, continued transport and mixing of the reactants. A reactive transport model with fully implicit coupling between diffusion, chemical speciation and precipitation kinetics, but where explicit details of nucleation processes were neglected, was able to qualitatively simulate properties of the precipitation zones. The results help to illustrate how changes in the physical properties of a precipitation zone depend on coupling between diffusion-controlled reactant mixing and chemistry-specific details of precipitation kinetics.

  16. Carbon storage in the deep reducing mantle

    NASA Astrophysics Data System (ADS)

    Rohrbach, A.; Ghosh, S.; Schmidt, M. W.; Wijbrans, C. H.; Klemme, S.

    2014-12-01

    To understand the storage and cycling of carbon in/through Earth's deep mantle it is vital to examine carbon speciations at relevant pressure, temperature, and oxygen fugacity (fO2). In particular redox conditions of the mantle critically influence the mobility of carbon bearing phases in the silicate matrix; oxidized species are generally more mobile (carbonatites, carbonated silicate melts) or have a larger impact on silicate solidi (carbonated peridotite/eclogite) than reduced species (diamond, carbides, metals). Within garnet bearing mantle lithologies, fO2 can be expected to decrease with depth [1], eventually reaching values similar to the iron-wüstite equilibrium which implies the precipitation of a Fe-Ni metal phase at pressures corresponding to the base of the upper mantle [2]. Because Ni is more noble than Fe, Ni partitions strongly into the reduced phases such that at low metal fractions the metal phase reaches XNi > 0.5. Thermodynamic calculations suggest that the mantle contains ~0.1 wt.% Fe,Ni metal at ~300 km depth [3], increasing to ~1 wt% in the lower mantle [4]. To understand the nature of carbon bearing reduced phases in the Earth mantle, we examine experimentally phase relations and melting behavior in the system Fe-Ni-C at 10 and 23 GPa. Dependent on Fe-Ni ratio and related fO2, C content, P and T we observe a variety of phases, namely (Fe,Ni)3C and (Fe,Ni)7C3 carbides, carbon bearing Fe-Ni metal, diamond and carbon rich metal-melt. In the subsolidus, mantle bulk C contents of 50 to 500 ppm [5] would result in the phase association (Fe,Ni)3C + metal + diamond at 10 GPa. In the uppermost lower mantle, about 1 wt.% metal would dissolve ca. 100 ppm C, any further C would lead to (Fe,Ni)3C carbide saturation. The solidus temperatures of theses phase assemblages however are considerably lower than the geotherm at upper and lower mantle pressures. We therefore suggest that reduced carbon bearing phases in the deep mantle are largely molten [6]. [1

  17. Strain-Specific Ureolytic Microbial Calcium Carbonate Precipitation

    PubMed Central

    Hammes, Frederik; Boon, Nico; de Villiers, Johan; Verstraete, Willy; Siciliano, Steven Douglas

    2003-01-01

    During a study of ureolytic microbial calcium carbonate (CaCO3) precipitation by bacterial isolates collected from different environmental samples, morphological differences were observed in the large CaCO3 crystal aggregates precipitated within bacterial colonies grown on agar. Based on these differences, 12 isolates were selected for further study. We hypothesized that the striking differences in crystal morphology were the result of different microbial species or, alternatively, differences in the functional attributes of the isolates selected. Sequencing of 16S rRNA genes showed that all of the isolates were phylogenetically closely related to the Bacillus sphaericus group. Urease gene diversity among the isolates was examined by using a novel application of PCR-denaturing gradient gel electrophoresis (DGGE). This approach revealed significant differences between the isolates. Moreover, for several isolates, multiple bands appeared on the DGGE gels, suggesting the apparent presence of different urease genes in these isolates. The substrate affinities (Km) and maximum hydrolysis rates (Vmax) of crude enzyme extracts differed considerably for the different strains. For certain isolates, the urease activity increased up to 10-fold in the presence of 30 mM calcium, and apparently this contributed to the characteristic crystal formation by these isolates. We show that strain-specific calcification occurred during ureolytic microbial carbonate precipitation. The specificity was mainly due to differences in urease expression and the response to calcium. PMID:12902285

  18. Effect of calcium on adsorption capacity of powdered activated carbon.

    PubMed

    Li, Gang; Shang, Junteng; Wang, Ying; Li, Yansheng; Gao, Hong

    2013-12-01

    We investigated the effect of calcium ion on the adsorption of humic acid (HA) (as a target pollutant) by powered activated carbon. The HA adsorption isotherms at different pH and kinetics of two different solutions including HA alone and HA doped Ca(2+), were performed. It was showed that the adsorption capacity of powdered activated carbon (PAC) for HA was markedly enhanced when Ca(2+) was doped into HA. Also, HA and Ca(2+) taken as nitrate were tested on the uptake of each other respectively and it was showed that the adsorbed amounts of both of them were significantly promoted when HA and calcium co-existed. Furthermore, the adsorbed amount of HA slightly decreased with the increasing of Ca(2+) concentration, whereas the amount of calcium increased with the increasing of HA concentration, but all above the amounts without addition. Finally, the change of pH before and after adsorption process is studied. In the two different solutions including HA alone and HA doped Ca(2+), pH had a small rise, but the extent of pH of later solution was bigger. PMID:25078809

  19. Bacillus subtilis Gene Cluster Involved in Calcium Carbonate Biomineralization▿

    PubMed Central

    Barabesi, Chiara; Galizzi, Alessandro; Mastromei, Giorgio; Rossi, Mila; Tamburini, Elena; Perito, Brunella

    2007-01-01

    Calcium carbonate precipitation, a widespread phenomenon among bacteria, has been investigated due to its wide range of scientific and technological implications. Nevertheless, little is known of the molecular mechanisms by which bacteria foster calcium carbonate mineralization. In our laboratory, we are studying calcite formation by Bacillus subtilis, in order to identify genes involved in the biomineralization process. A previous screening of UV mutants and of more than one thousand mutants obtained from the European B. subtilis Functional Analysis project allowed us to isolate strains altered in the precipitation phenotype. Starting from these results, we focused our attention on a cluster of five genes (lcfA, ysiA, ysiB, etfB, and etfA) called the lcfA operon. By insertional mutagenesis, mutant strains carrying each of the five genes were produced. All of them, with the exception of the strain carrying the mutated lcfA operon, were unable to form calcite crystals. By placing transcription under IPTG (isopropyl-β-d-thiogalactopyranoside) control, the last gene, etfA, was identified as essential for the precipitation process. To verify cotranscription in the lcfA operon, reverse transcription-PCR experiments were performed and overlapping retrocotranscripts were found comprising three adjacent genes. The genes have putative functions linked to fatty acid metabolism. A link between calcium precipitation and fatty acid metabolism is suggested. PMID:17085570

  20. Absorption of inorganic halides produced from Freon 12 by calcium carbonate containing iron(III) oxide

    SciTech Connect

    Imamura, Seiichiro; Matsuba, Yoichi; Yamada, Etsu; Takai, Kenji; Utani, Kazunori

    1997-09-01

    Inorganic halides produced by the catalytic decomposition of Freon 12 were fixed by calcium carbonate, which is the main component of limestone. Iron(III) oxide, which is present as a contaminant in limestone, promoted the absorption of the halides by calcium carbonate at low temperatures. The supposed action of iron(III) oxide was to first react with inorganic halides, forming iron halides, and, then, transfer them to calcium carbonate to replace carbonate ion in a catalytic way. Thus, calcium carbonate containing iron oxides (limestone) can be used as an effective absorbent for the inorganic halogens produced during the decomposition of Freons.

  1. Calcium carbonate-calcium phosphate mixed cement compositions for bone reconstruction.

    PubMed

    Combes, C; Bareille, R; Rey, C

    2006-11-01

    The feasibility of making calcium carbonate-calcium phosphate (CaCO(3)-CaP) mixed cements, comprising at least 40% (w/w) CaCO(3) in the dry powder ingredients, has been demonstrated. Several original cement compositions were obtained by mixing metastable crystalline CaCO(3) phases with metastable amorphous or crystalline CaP powders in aqueous medium. The cements set within at most 1 h at 37 degrees C in atmosphere saturated with water. The hardened cement is microporous and exhibits weak compressive strength. The setting reaction appeared to be essentially related to the formation of a highly carbonated nanocrystalline apatite phase by reaction of the metastable CaP phase with part or almost all of the metastable CaCO(3) phase. The recrystallization of metastable CaP varieties led to a final cement consisting of a highly carbonated poorly crystalline apatite analogous to bone mineral associated with various amounts of vaterite and/or aragonite. The presence of controlled amounts of CaCO(3) with a higher solubility than that of the apatite formed in the well-developed CaP cements might be of interest to increase resorption rates in biomedical cement and favors its replacement by bone tissue. Cytotoxicity testing revealed excellent cytocompatibility of CaCO(3)-CaP mixed cement compositions.

  2. Carbonate-containing apatite (CAP) synthesis under moderate conditions starting from calcium carbonate and orthophosphoric acid.

    PubMed

    Pham Minh, Doan; Tran, Ngoc Dung; Nzihou, Ange; Sharrock, Patrick

    2013-07-01

    The synthesis of carbonate-containing apatite (CAP) from calcium carbonate and orthophosphoric acid under moderate conditions was investigated. In all cases, complete precipitation of orthophosphate species was observed. The reaction temperature influenced strongly the decomposition of calcium carbonate and therefore the composition of formed products. The reaction temperature of 80 °C was found to be effective for the complete decomposition of calcium carbonate particles after 48 h of reaction. Infra-red spectroscopy (IR), nuclear magnetic resonance (NMR), thermogravimetry/mass spectroscopy (TG-MS) coupling, and X-ray diffraction (XRD) characterizations allowed the identification of the composition of formed products. By increasing the reaction temperature from 20 °C to 80 °C, the content of A-type CAP increased and that of B-type CAP decreased, according to the favorable effect of temperature on the formation of A-type CAP. The total amount of carbonate content incorporated in CAP's structure, which was determined by TG-MS analysis, increased with the reaction temperature and reached up to 4.1% at 80 °C. At this temperature, the solid product was mainly composed of apatitic components and showed the typical flat-needle-like structure of CAP particles obtained in hydrothermal conditions. These results show an interesting one-step synthesis of CAP from calcium carbonate and orthophosphoric acid as low cost but high purity starting materials.

  3. Evaluation of cellular influences caused by calcium carbonate nanoparticles.

    PubMed

    Horie, Masanori; Nishio, Keiko; Kato, Haruhisa; Endoh, Shigehisa; Fujita, Katsuhide; Nakamura, Ayako; Kinugasa, Shinichi; Hagihara, Yoshihisa; Yoshida, Yasukazu; Iwahashi, Hitoshi

    2014-03-01

    The cellular effects of calcium carbonate (CaCO₃) nanoparticles were evaluated. Three kinds of CaCO₃ nanoparticles were employed in our examinations. One of the types of CaCO₃ nanoparticles was highly soluble. And solubility of another type of CaCO₃ nanoparticle was lower. A stable CaCO₃ nanoparticle medium dispersion was prepared and applied to human lung carcinoma A549 cells and human keratinocyte HaCaT cells. Then, mitochondrial activity, cell membrane damage, colony formation ability, DNA injury, induction of oxidative stress, and apoptosis were evaluated. Although the influences of CaCO₃ nanoparticles on mitochondrial activity and cell membrane damage were small, "soluble" CaCO₃ nanoparticles exerted some cellular influences. Soluble CaCO₃ nanoparticles also induced a cell morphological change. Colony formation was inhibited by CaCO₃ nanoparticle exposure. In particular, soluble CaCO₃ nanoparticles completely inhibited colony formation. The influence on intracellular the reactive oxygen species (ROS) level was small. Soluble CaCO₃ nanoparticles caused an increase in C/EBP-homologous protein (CHOP) expression and the activation of caspase-3. Moreover, CaCO₃ exposure increased intracellular the Ca²⁺ level and activated calpain. These results suggest that cellular the influences of CaCO₃ nanoparticles are mainly caused by intracellular calcium release and subsequently disrupt the effect of calcium signaling. In conclusion, there is possibility that soluble CaCO₃ nanoparticles induce cellular influences such as a cell morphological change. Cellular influence of CaCO₃ nanoparticles is caused by intracellular calcium release. If inhaled CaCO₃ nanoparticles have the potential to influence cellular events. However, the effect might be not severe because calcium is omnipresent element in cell.

  4. Alginate hydrogel-mediated crystallization of calcium carbonate

    SciTech Connect

    Ma, Yufei; Feng, Qingling

    2011-05-15

    We documented a specific method for combining calcium ions and alginate molecules slowly and continuously in the mineralization system for the purpose of understanding the mediating function of alginate on the crystallization of calcium carbonate. The alginate was involved in the nucleation and the growth process of CaCO{sub 3}. The crystal size, morphology and roughness of crystal surface were significantly influenced by the type of the alginate, which could be accounted for by the length of the G blocks in alginate. A combination of Fourier transform infrared spectroscopy and thermogravimetric analysis showed that there were the chemical interactions between the alginate and the mineral phase. This strategic approach revealed the biologically controlled CaCO{sub 3} mineralization within calcium alginate hydrogels via the selective nucleation and the confined crystallization of CaCO{sub 3}. The results presented here could contribute to the understanding of the mineralization process in hydrogel systems. -- Graphical abstract: Schematic illustration of the growth of calcite aggregates with different morphologies obtained from (a) Low G alginate gels and (b) High G alginate gels. Display Omitted highlights: > We use a specific method for combining calcium ions and alginate molecules slowly and continuously in the mineralization system to understand the mediating function of alginate on the crystallization of CaCO{sub 3} crystals. > The crystal size, morphology and crystal surface roughness are influenced by the length of G blocks in alginate. There are chemical interactions between the alginate and the mineral phase. > We propose a potential mechanism of CaCO{sub 3} crystallization within High G and Low G calcium alginate hydrogel.

  5. Multi-Functions of Carbonated Calcium Deficient Hydroxyapatite (CDHA)

    NASA Astrophysics Data System (ADS)

    Zhou, Huan

    Natural bone is a complex composite mainly constituted of inorganic minerals and organic collagen molecules. Calcium phosphate (CaP) based materials have been proposed as the predominant bone substitute for bone tissue engineering applications due to their chemical similarity to bone mineral. Amorphous carbonated calcium deficient hydroxyapatite (CDHA) is an important compound among CaP materials because of the amorphous crystallite structure. The presence of extra ions in its lattice structure not only influences cell attachment and proliferation of osteoblasts, but also helps in bone metabolism. Biomimetic coating approach is the most widely used approach to produce CDHA coatings to implant. It is a process using simulated body fluid (SBF) to deposit bone-like CDHA coating to various material surfaces. The CDHA formation mechanism, SBF compositions and reacting conditions of biomimetic coating have already been sufficiently studied and compared in the past 20 years. It is an attempt in this thesis to explore new applications of SBF in biomedical research, focusing on different biomaterial applications: 1) based on the low temperature reaction condition of SBF, bisphosphonate incorporated CDHA coatings were deposited onto Ti6Al4V surface for the treatment of osteoporosis; 2) amorphous calcium phosphate nanospheres with extra elements in the lattice structure were prepared by a novel microwave assisted approach, providing a new potential of CaP materials production; 3) CDHA particles formed in SBF can be used as great fillers with biopolymers for preparing biocomposites for biomedical applications; 4) based on the high activity of CDHA amorphous structure and the stabilization ability of ethanol, yttrium and europium doped calcium phosphates were prepared using CDHA as a sacrificing template. In the end, future work based on these observations in the thesis is addressed, including areas of drug delivery, biocomposite fabrication and preparation of functionalized

  6. Transglutaminase-induced crosslinking of gelatin-calcium carbonate composite films.

    PubMed

    Wang, Yuemeng; Liu, Anjun; Ye, Ran; Wang, Wenhang; Li, Xin

    2015-01-01

    The effects of transglutaminase (TGase) on the rheological profiles and interactions of gelatin-calcium carbonate solutions were studied. In addition, mechanical properties, water vapour permeability and microstructures of gelatin-calcium carbonate films were also investigated and compared. Fluorescence data suggested that the interaction of TGase and gelation-calcium carbonate belonged to a static quenching mechanism, and merely one binding site between TGase and gelatin-calcium carbonate was identified. Moreover, differential scanning calorimetry (DSC), the mechanical properties and the water vapour permeability studies revealed that TGase favoured the strong intramolecular polymerisation of the peptides in gelatin. The microstructures of the surfaces and cross sections in gelatin-calcium carbonate films were shown by scanning electron microscope (SEM) micrographs. The results of the fourier transform infrared spectroscopy (FTIR) indicated that TGase caused conformational changes in the proteins films. Therefore, TGase successfully facilitated the formation of gelatin-calcium carbonate composite films.

  7. Nacre-like calcium carbonate controlled by ionic liquid/graphene oxide composite template.

    PubMed

    Yao, Chengli; Xie, Anjian; Shen, Yuhua; Zhu, Jinmiao; Li, Hongying

    2015-06-01

    Nacre-like calcium carbonate nanostructures have been mediated by an ionic liquid (IL)-graphene oxide (GO) composite template. The resultant crystals were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffractometry (XRD). The results showed that either 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) or graphene oxide can act as a soft template for calcium carbonate formation with unusual morphologies. Based on the time-dependent morphology changes of calcium carbonate particles, it is concluded that nacre-like calcium carbonate nanostructures can be formed gradually utilizing [BMIM]BF4/GO composite template. During the process of calcium carbonate formation, [BMIM]BF4 acted not only as solvents but also as morphology templates for the fabrication of calcium carbonate materials with nacre-like morphology. Based on the observations, the possible mechanisms were also discussed.

  8. Nacre-like calcium carbonate controlled by ionic liquid/graphene oxide composite template.

    PubMed

    Yao, Chengli; Xie, Anjian; Shen, Yuhua; Zhu, Jinmiao; Li, Hongying

    2015-06-01

    Nacre-like calcium carbonate nanostructures have been mediated by an ionic liquid (IL)-graphene oxide (GO) composite template. The resultant crystals were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and X-ray powder diffractometry (XRD). The results showed that either 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) or graphene oxide can act as a soft template for calcium carbonate formation with unusual morphologies. Based on the time-dependent morphology changes of calcium carbonate particles, it is concluded that nacre-like calcium carbonate nanostructures can be formed gradually utilizing [BMIM]BF4/GO composite template. During the process of calcium carbonate formation, [BMIM]BF4 acted not only as solvents but also as morphology templates for the fabrication of calcium carbonate materials with nacre-like morphology. Based on the observations, the possible mechanisms were also discussed. PMID:25842135

  9. Increased calcium absorption from synthetic stable amorphous calcium carbonate: double-blind randomized crossover clinical trial in postmenopausal women.

    PubMed

    Vaisman, Nachum; Shaltiel, Galit; Daniely, Michal; Meiron, Oren E; Shechter, Assaf; Abrams, Steven A; Niv, Eva; Shapira, Yami; Sagi, Amir

    2014-10-01

    Calcium supplementation is a widely recognized strategy for achieving adequate calcium intake. We designed this blinded, randomized, crossover interventional trial to compare the bioavailability of a new stable synthetic amorphous calcium carbonate (ACC) with that of crystalline calcium carbonate (CCC) using the dual stable isotope technique. The study was conducted in the Unit of Clinical Nutrition, Tel Aviv Sourasky Medical Center, Israel. The study population included 15 early postmenopausal women aged 54.9 ± 2.8 (mean ± SD) years with no history of major medical illness or metabolic bone disorder, excess calcium intake, or vitamin D deficiency. Standardized breakfast was followed by randomly provided CCC or ACC capsules containing 192 mg elemental calcium labeled with 44Ca at intervals of at least 3 weeks. After swallowing the capsules, intravenous CaCl2 labeled with 42Ca on was administered on each occasion. Fractional calcium absorption (FCA) of ACC and CCC was calculated from the 24-hour urine collection following calcium administration. The results indicated that FCA of ACC was doubled (± 0.96 SD) on average compared to that of CCC (p < 0.02). The higher absorption of the synthetic stable ACC may serve as a more efficacious way of calcium supplementation.

  10. Epitaxial relationships between calcium carbonate and inorganic substrates.

    PubMed

    Yang, Taewook; Jho, Jae Young; Kim, Il Won

    2014-09-15

    The polymorph-selective crystallization of calcium carbonate has been studied in terms of epitaxial relationship between the inorganic substrates and the aragonite/calcite polymorphs with implication in bioinspired mineralization. EpiCalc software was employed to assess the previously published experimental results on two different groups of inorganic substrates: aragonitic carbonate crystals (SrCO3, PbCO3, and BaCO3) and a hexagonal crystal family (α-Al2O3, α-SiO2, and LiNbO3). The maximum size of the overlayer (aragonite or calcite) was calculated for each substrate based on a threshold value of the dimensionless potential to estimate the relative nucleation preference of the polymorphs of calcium carbonate. The results were in good agreement with previous experimental observations, although stereochemical effects between the overlayer and substrate should be separately considered when existed. In assessing the polymorph-selective nucleation, the current method appeared to provide a better tool than the oversimplified mismatch parameters without invoking time-consuming molecular simulation.

  11. Design of a continuous process setup for precipitated calcium carbonate production from steel converter slag.

    PubMed

    Mattila, Hannu-Petteri; Zevenhoven, Ron

    2014-03-01

    A mineral carbonation process "slag2PCC" for carbon capture, utilization, and storage is discussed. Ca is extracted from steel slag by an ammonium salt solvent and carbonated with gaseous CO2 after the separation of the residual slag. The solvent is reused after regeneration. The effects of slag properties such as the content of free lime, fractions of Ca, Si, Fe, and V, particle size, and slag storage on the Ca extraction efficiency are studied. Small particles with a high free-lime content and minor fractions of Si and V are the most suitable. To limit the amount of impurities in the process, the slag-to-liquid ratio should remain below a certain value, which depends on the slag composition. Also, the design of a continuous test setup (total volume ∼75 L) is described, which enables quick process variations needed to adapt the system to the varying slag quality. Different precipitated calcium carbonate crystals (calcite and vaterite) are generated in different parts of the setup.

  12. Bivalves build their shells from amorphous calcium carbonate

    NASA Astrophysics Data System (ADS)

    Jacob, D. E.; Wirth, R.; Soldati, A. L.; Wehrmeister, U.

    2012-04-01

    One of the most common shell structures in the bivalve class is the prism and nacre structure. It is widely distributed amongst both freshwater and marine species and gives cultured pearls their sought-after lustre. In freshwater bivalves, both shell structures (prism and nacre) consist of aragonite. Formation of the shell form an amorphous precursor phase is a wide-spread strategy in biomineralization and presents a number of advantages for the organisms in the handling of the CaCO3 material. While there is already evidence that larval shells of some mollusk species use amorphous calcium carbonate (ACC) as a transient precursor phase for aragonite, the use of this strategy by adult animals was only speculated upon. We present results from in-situ geochemistry, Raman spectroscopy and focused-ion beam assisted TEM on three species from two different bivalve families that show that remnants of ACC can be found in shells from adult species. We show that the amorphous phase is not randomly distributed, but is systematically found in a narrow zone at the interface between periostracum and prism layer. This zone is the area where spherulitic CaCO3- structures protrude from the inner periostracum to form the initial prisms. These observations are in accordance with our earlier results on equivalent structures in freshwater cultured pearls (Jacob et al., 2008) and show that the original building material for the prisms is amorphous calcium carbonate, secreted in vesicles at the inner periostracum layer. Quantitative temperature calibrations for paleoclimate applications using bivalve shells are based on the Mg-Ca exchange between inorganic aragonite (or calcite) and water. These calibrations, thus, do not take into account the biomineral crystallization path via an amorphous calcium carbonate precursor and are therefore likely to introduce a bias (a so-called vital effect) which currently is not accounted for. Jacob et al. (2008) Geochim. Cosmochim. Acta 72, 5401-5415

  13. Constraints on Biogenic Emplacement of Crystalline Calcium Carbonate and Dolomite

    NASA Astrophysics Data System (ADS)

    Colas, B.; Clark, S. M.; Jacob, D. E.

    2015-12-01

    Amorphous calcium carbonate (ACC) is a biogenic precursor of calcium carbonates forming shells and skeletons of marine organisms, which are key components of the whole marine environment. Understanding carbonate formation is an essential prerequisite to quantify the effect climate change and pollution have on marine population. Water is a critical component of the structure of ACC and the key component controlling the stability of the amorphous state. Addition of small amounts of magnesium (1-5% of the calcium content) is known to promote the stability of ACC presumably through stabilization of the hydrogen bonding network. Understanding the hydrogen bonding network in ACC is fundamental to understand the stability of ACC. Our approach is to use Monte-Carlo simulations constrained by X-ray and neutron scattering data to determine hydrogen bonding networks in ACC as a function of magnesium doping. We have already successfully developed a synthesis protocol to make ACC, and have collected X-ray data, which is suitable for determining Ca, Mg and O correlations, and have collected neutron data, which gives information on the hydrogen/deuterium (as the interaction of X-rays with hydrogen is too low for us to be able to constrain hydrogen atom positions with only X-rays). The X-ray and neutron data are used to constrain reverse Monte-Carlo modelling of the ACC structure using the Empirical Potential Structure Refinement program, in order to yield a complete structural model for ACC including water molecule positions. We will present details of our sample synthesis and characterization methods, X-ray and neutron scattering data, and reverse Monte-Carlo simulations results, together with a discussion of the role of hydrogen bonding in ACC stability.

  14. Calcium isotope evidence for suppression of carbonate dissolution in carbonate-bearing organic-rich sediments

    NASA Astrophysics Data System (ADS)

    Turchyn, Alexandra V.; DePaolo, Donald J.

    2011-11-01

    Pore fluid calcium isotope, calcium concentration and strontium concentration data are used to measure the rates of diagenetic dissolution and precipitation of calcite in deep-sea sediments containing abundant clay and organic material. This type of study of deep-sea sediment diagenesis provides unique information about the ultra-slow chemical reactions that occur in natural marine sediments that affect global geochemical cycles and the preservation of paleo-environmental information in carbonate fossils. For this study, calcium isotope ratios (δ 44/40Ca) of pore fluid calcium from Ocean Drilling Program (ODP) Sites 984 (North Atlantic) and 1082 (off the coast of West Africa) were measured to augment available pore fluid measurements of calcium and strontium concentration. Both study sites have high sedimentation rates and support quantitative sulfate reduction, methanogenesis and anaerobic methane oxidation. The pattern of change of δ 44/40Ca of pore fluid calcium versus depth at Sites 984 and 1082 differs markedly from that of previously studied deep-sea Sites like 590B and 807, which are composed of nearly pure carbonate sediment. In the 984 and 1082 pore fluids, δ 44/40Ca remains elevated near seawater values deep in the sediments, rather than shifting rapidly toward the δ 44/40Ca of carbonate solids. This observation indicates that the rate of calcite dissolution is far lower than at previously studied carbonate-rich sites. The data are fit using a numerical model, as well as more approximate analytical models, to estimate the rates of carbonate dissolution and precipitation and the relationship of these rates to the abundance of clay and organic material. Our models give mutually consistent results and indicate that calcite dissolution rates at Sites 984 and 1082 are roughly two orders of magnitude lower than at previously studied carbonate-rich sites, and the rate correlates with the abundance of clay. Our calculated rates are conservative for these

  15. Fracture of ultrafine calcium carbonate/polypropylene composites

    SciTech Connect

    Levita, G.; Marchetti, A.; Lazzeri, A.

    1989-02-01

    The strength and fracture properties of a polypropylene filled with ultrafine calcium carbonate (0.07 micron) have been studied in the composition range of 0 to 40 percent by volume. Untreated and surface treated (with stearic acid and a titanate coupling agent) grades have been considered. The untreated filler caused a decrease of toughness, whereas a maximum, at about 10 percent, was observed for the treated filler. The fracture energy was analyzed in terms of the crack-pinning model. Due to the very small size of particles, the pinning contribution proved to be negligible. 30 references.

  16. Calcium carbonate production, coral reef growth, and sea level change.

    PubMed

    Smith, S V; Kinsey, D W

    1976-11-26

    Shallow, seaward portions of modern coral reefs produce about 4 kilograms of calcium carbonate per square meter per year, and protected areas produce about 0.8 kilogram per square meter per year. The difference is probably largely a function of water motion. The more rapid rate, equivalent to a maximum vertical accretion of 3 to 5 millimeters per year, places an upper limit on the potential of modern coral reef communities to create a significant vertical structure on a rising sea. PMID:17748553

  17. 46 CFR 193.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Carbon dioxide storage. 193.15-20 Section 193.15-20... PROTECTION EQUIPMENT Carbon Dioxide and Clean Agent Extinguishing Systems, Details § 193.15-20 Carbon dioxide...-5(d), consisting of not more than 300 pounds of carbon dioxide, may have cylinders located...

  18. 46 CFR 193.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Carbon dioxide storage. 193.15-20 Section 193.15-20... PROTECTION EQUIPMENT Carbon Dioxide and Clean Agent Extinguishing Systems, Details § 193.15-20 Carbon dioxide...-5(d), consisting of not more than 300 pounds of carbon dioxide, may have cylinders located...

  19. 46 CFR 193.15-20 - Carbon dioxide storage.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Carbon dioxide storage. 193.15-20 Section 193.15-20... PROTECTION EQUIPMENT Carbon Dioxide and Clean Agent Extinguishing Systems, Details § 193.15-20 Carbon dioxide...-5(d), consisting of not more than 300 pounds of carbon dioxide, may have cylinders located...

  20. Spectral features of biogenic calcium carbonates and implications for astrobiology

    NASA Astrophysics Data System (ADS)

    Berg, B. L.; Ronholm, J.; Applin, D. M.; Mann, P.; Izawa, M.; Cloutis, E. A.; Whyte, L. G.

    2014-09-01

    The ability to discriminate biogenic from abiogenic calcium carbonate (CaCO3) would be useful in the search for extant or extinct life, since CaCO3 can be produced by both biotic and abiotic processes on Earth. Bioprecipitated CaCO3 material was produced during the growth of heterotrophic microbial isolates on medium enriched with calcium acetate or calcium citrate. These biologically produced CaCO3, along with natural and synthetic non-biologically produced CaCO3 samples, were analysed by reflectance spectroscopy (0.35-2.5 μm), Raman spectroscopy (532 and 785 nm), and laser-induced fluorescence spectroscopy (365 and 405 nm excitation). Optimal instruments for the discrimination of biogenic from abiogenic CaCO3 were determined to be reflectance spectroscopy, and laser-induced fluorescence spectroscopy. Multiple absorption features in the visible light region occurred in reflectance spectra for most biogenic CaCO3 samples, which are likely due to organic pigments. Multiple fluorescence peaks occurred in emission spectra (405 nm excitation) of biogenic CaCO3 samples, which also are best attributed to the presence of organic compounds; however, further analyses must be performed in order to better determine the cause of these features to establish criteria for confirming the origin of a given CaCO3 sample. Raman spectroscopy was not useful for discrimination since any potential Raman peaks in spectra of biogenic carbonates collected by both the 532 and 785 nm lasers were overwhelmed by fluorescence. However, this also suggests that biogenic carbonates may be identified by the presence of this organic-associated fluorescence. No reliable spectroscopic differences in terms of parameters such as positions or widths of carbonate-associated absorption bands were found between the biogenic and abiogenic carbonate samples. These results indicate that the presence or absence of organic matter intimately associated with carbonate minerals is the only potentially useful

  1. Carbon nanotube materials for hydrogen storage

    SciTech Connect

    Dillon, A.C.; Parilla, P.A.; Jones, K.M.; Riker, G.; Heben, M.J.

    1998-08-01

    Carbon single-wall nanotubes (SWNTs) are essentially elongated pores of molecular dimensions and are capable of adsorbing hydrogen at relatively high temperatures and low pressures. This behavior is unique to these materials and indicates that SWNTs are the ideal building block for constructing safe, efficient, and high energy density adsorbents for hydrogen storage applications. In past work the authors developed methods for preparing and opening SWNTs, discovered the unique adsorption properties of these new materials, confirmed that hydrogen is stabilized by physical rather than chemical interactions, measured the strength of interaction to be {approximately} 5 times higher than for adsorption on planar graphite, and performed infrared absorption spectroscopy to determine the chemical nature of the surface terminations before, during, and after oxidation. This year the authors have made significant advances in synthesis and characterization of SWNT materials so that they can now prepare gram quantities of high-purity SWNT samples and measure and control the diameter distribution of the tubes by varying key parameters during synthesis. They have also developed methods which purify nanotubes and cut nanotubes into shorter segments. These capabilities provide a means for opening the tubes which were unreactive to the oxidation methods that successfully opened tubes, and offer a path towards organizing nanotube segments to enable high volumetric hydrogen storage densities. They also performed temperature programmed desorption spectroscopy on high purity carbon nanotube material obtained from collaborator Prof. Patrick Bernier and finished construction of a high precision Seivert`s apparatus which will allow the hydrogen pressure-temperature-composition phase diagrams to be evaluated for SWNT materials.

  2. Analysis of barium hydroxide and calcium hydroxide slurry carbonation reactors

    SciTech Connect

    Patch, K.D.; Hart, R.P.; Schumacher, W.A.

    1980-05-01

    The removal of CO/sub 2/ from air was investigated by using a continuous-agitated-slurry carbonation reactor containing either barium hydroxide (Ba(OH)/sub 2/) or calcium hydroxide (Ca(OH)/sub 2/). Such a process would be applied to scrub /sup 14/CO/sub 2/ from stack gases at nuclear-fuel reprocessing plants. Decontamination factors were characterized for reactor conditions which could alter hydrodynamic behavior. An attempt was made to characterize reactor performance with models assuming both plug flow and various degrees of backmixing in the gas phase. The Ba(OH)/sub 2/ slurry enabled increased conversion, but apparently the process was controlled under some conditions by phenomena differing from those observed for carbonation by Ca(OH)/sub 2/. Overall reaction mechanisms are postulated.

  3. Is Carbon Capture and Storage Really Needed?

    SciTech Connect

    Tsouris, Costas; Williams, Kent Alan; Aaron, D

    2010-01-01

    Two of the greatest contemporary global challenges are anthropogenic greenhouse gas emissions and energy sustainability. A popular proposed solution to the former problem is carbon capture and storage (CCS). Unfortunately, CCS has little benefit for energy sustainability and introduces significant long-term costs and risks. Thus, we propose the adoption of 'virtual CCS' by directing the resources that would have been spent on CCS to alternative energy technologies. (The term 'virtual' is used here because the concept described in this work satisfies the Merriam-Webster Dictionary definition of virtual: 'being such in essence or effect though not formally recognized or admitted.') In this example, we consider wind and nuclear power and use the funds that would have been required by CCS to invest in installation and operation of these technologies. Many other options exist in addition to wind and nuclear power including solar, biomass, geothermal, and others. These additional energy technologies can be considered in future studies. While CCS involves spending resources to concentrate CO{sub 2} in sinks, such as underground reservoirs, low-carbon alternative energy produces power, which will displace fossil fuel use while simultaneously generating revenues. Thus, these alternative energy technologies achieve the same objective as that of CCS, namely, the avoidance of atmospheric CO{sub 2} emissions.

  4. Calcium Carbonate Precipitation by Bacillus and Sporosarcina Strains Isolated from Concrete and Analysis of the Bacterial Community of Concrete.

    PubMed

    Kim, Hyun Jung; Eom, Hyo Jung; Park, Chulwoo; Jung, Jaejoon; Shin, Bora; Kim, Wook; Chung, Namhyun; Choi, In-Geol; Park, Woojun

    2016-03-01

    Microbially induced calcium carbonate precipitation (CCP) is a long-standing but re-emerging environmental engineering process for production of self-healing concrete, bioremediation, and long-term storage of CO2. CCP-capable bacteria, two Bacillus strains (JH3 and JH7) and one Sporosarcina strain (HYO08), were isolated from two samples of concrete and characterized phylogenetically. Calcium carbonate crystals precipitated by the three strains were morphologically distinct according to field emission scanning electron microscopy. Energy dispersive X-ray spectrometry mapping confirmed biomineralization via extracellular calcium carbonate production. The three strains differed in their physiological characteristics: growth at alkali pH and high NaCl concentrations, and urease activity. Sporosarcina sp. HYO08 and Bacillus sp. JH7 were more alkali- and halotolerant, respectively. Analysis of the community from the same concrete samples using barcoded pyrosequencing revealed that the relative abundance of Bacillus and Sporosarcina species was low, which indicated low culturability of other dominant bacteria. This study suggests that calcium carbonate crystals with different properties can be produced by various CCP-capable strains, and other novel isolates await discovery. PMID:26699752

  5. Calcium Carbonate Precipitation by Bacillus and Sporosarcina Strains Isolated from Concrete and Analysis of the Bacterial Community of Concrete.

    PubMed

    Kim, Hyun Jung; Eom, Hyo Jung; Park, Chulwoo; Jung, Jaejoon; Shin, Bora; Kim, Wook; Chung, Namhyun; Choi, In-Geol; Park, Woojun

    2016-03-01

    Microbially induced calcium carbonate precipitation (CCP) is a long-standing but re-emerging environmental engineering process for production of self-healing concrete, bioremediation, and long-term storage of CO2. CCP-capable bacteria, two Bacillus strains (JH3 and JH7) and one Sporosarcina strain (HYO08), were isolated from two samples of concrete and characterized phylogenetically. Calcium carbonate crystals precipitated by the three strains were morphologically distinct according to field emission scanning electron microscopy. Energy dispersive X-ray spectrometry mapping confirmed biomineralization via extracellular calcium carbonate production. The three strains differed in their physiological characteristics: growth at alkali pH and high NaCl concentrations, and urease activity. Sporosarcina sp. HYO08 and Bacillus sp. JH7 were more alkali- and halotolerant, respectively. Analysis of the community from the same concrete samples using barcoded pyrosequencing revealed that the relative abundance of Bacillus and Sporosarcina species was low, which indicated low culturability of other dominant bacteria. This study suggests that calcium carbonate crystals with different properties can be produced by various CCP-capable strains, and other novel isolates await discovery.

  6. Effects of nano calcium carbonate and nano calcium citrate on toxicity in ICR mice and on bone mineral density in an ovariectomized mice model

    NASA Astrophysics Data System (ADS)

    Huang, Sherry; Chen, Jin Ching; Hsu, Chin Wei; Chang, Walter H.

    2009-09-01

    Taking calcium supplements can reduce the risk of developing osteoporosis, but they are not readily absorbed in the gastrointestinal tract. Nanotechnology is expected to resolve this problem. In the present study, we examined whether the bioavailability of calcium carbonate and calcium citrate can be improved by reducing the particle size. The morphology of nano calcium carbonate and nano calcium citrate was characterized by dynamic laser-light scattering (DLS), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The measurements obtained from DLS, FE-SEM and TEM were comparable. Acute and sub-chronic toxicity tests were performed to establish the safety of these products after oral administration. The no-observed-adverse-effect levels of nano calcium carbonate and nano calcium citrate were 1.3 and 2.3 g kg-1 body weight, respectively. The results of our in vivo studies indicate that administering nano calcium carbonate and nano calcium citrate can enhance the serum calcium concentration and maintain the whole-body bone mineral density in ovariectomized mice. These data suggest that nano calcium carbonate and nano calcium citrate are more bioavailable than micro calcium carbonate and micro calcium citrate, respectively.

  7. Effects of nano calcium carbonate and nano calcium citrate on toxicity in ICR mice and on bone mineral density in an ovariectomized mice model.

    PubMed

    Huang, Sherry; Chen, Jin Ching; Hsu, Chin Wei; Chang, Walter H

    2009-09-16

    Taking calcium supplements can reduce the risk of developing osteoporosis, but they are not readily absorbed in the gastrointestinal tract. Nanotechnology is expected to resolve this problem. In the present study, we examined whether the bioavailability of calcium carbonate and calcium citrate can be improved by reducing the particle size. The morphology of nano calcium carbonate and nano calcium citrate was characterized by dynamic laser-light scattering (DLS), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The measurements obtained from DLS, FE-SEM and TEM were comparable. Acute and sub-chronic toxicity tests were performed to establish the safety of these products after oral administration. The no-observed-adverse-effect levels of nano calcium carbonate and nano calcium citrate were 1.3 and 2.3 g kg(-1) body weight, respectively. The results of our in vivo studies indicate that administering nano calcium carbonate and nano calcium citrate can enhance the serum calcium concentration and maintain the whole-body bone mineral density in ovariectomized mice. These data suggest that nano calcium carbonate and nano calcium citrate are more bioavailable than micro calcium carbonate and micro calcium citrate, respectively.

  8. Protein mapping of calcium carbonate biominerals by immunogold.

    PubMed

    Marin, Frédéric; Pokroy, Boaz; Luquet, Gilles; Layrolle, Pierre; De Groot, Klaas

    2007-05-01

    The construction of metazoan calcium carbonate skeletons is finely regulated by a proteinaceous extracellular matrix, which remains embedded within the exoskeleton. In spite of numerous biochemical studies, the precise localization of skeletal proteins has remained for a long time as an elusive goal. In this paper, we describe a technique for visualizing shell matrix proteins on the surface of calcium carbonate crystals or within the biominerals. The technique is as follows: freshly broken pieces of biominerals or NaOCl then EDTA-etched polished surfaces are incubated with an antibody elicited against one matrix protein, then with a secondary gold-coupled antibody. After silver enhancement, the samples are subsequently observed with scanning electron microscopy by using back-scattered electron mode. In the present case, the technique is applied to a particular example, the calcitic prisms that compose the outer shell layer of the mediterranean fan mussel Pinna nobilis. One major soluble protein, caspartin, which was identified recently, was partly de novo sequenced after enzymatic digestions. A polyclonal antibody raised against caspartin was used for its localization within and on the prisms. The immunogold localization indicated that caspartin surrounds the calcitic prisms, but is also dispersed within the biominerals. This example illustrates the deep impact of the technique on the definition of intracrystalline versus intercrystalline matrix proteins. Furthermore, it is an important tool for assigning a putative function to a matrix protein of interest.

  9. Constitutive modeling of calcium carbonate supersaturated seawater mixtures

    NASA Astrophysics Data System (ADS)

    Reis, Martina; Sousa, Maria De Fátima; Bertran, Celso; Bassi, Adalberto

    2014-11-01

    Calcium carbonate supersaturated seawater mixtures have attracted attention of many researchers since the deposition of CaCO3(s) from such solutions can lead to scaling problems in oil fields. However, despite their evident practical importance in petroleum engineering, the hydro and thermodynamic behaviors of these mixtures have not been well-understood yet. In this work, a constitutive model based on the foundations of the constitutive theory of continuum mechanics, and the Müller-Liu entropy principle is proposed. The calcium carbonate supersaturated seawater mixture is regarded as a reactive viscous fluid with heat and electrical conductions. The obtained results indicate that the thermodynamic behavior of CaCO3 supersaturated seawater mixtures is closely related to the individual dynamics of each constituent of the mixture, particularly to the linear momentum, and mass exchanges. Furthermore, the results show that, unlike classical continuum mixtures, the extra entropy flux is not null, and higher-order gradients of deformation contribute to the residual entropy production of the class of mixtures under study. The results of this work may be relevant for the prevention of the mineral scale formation in oil fields. The first author acknowledges the São Paulo Research Foundation (Grant 2013/ 20872-2) for its funding.

  10. Uptake of chloride and carbonate ions by calcium monosulfoaluminate hydrate

    SciTech Connect

    Mesbah, Adel; Cau-dit-Coumes, Celine; Frizon, Fabien

    2012-08-15

    Decommissioning of old nuclear reactors may produce waste streams containing chlorides and carbonates, including radioactive {sup 36}Cl{sup -} and {sup 14}CO{sub 3}{sup 2-}. Their insolubilization by calcium monosulfoaluminate hydrate was investigated. Carbonates were readily depleted from the solution, giving at thermodynamic equilibrium monocarboaluminate, monocarboaluminate + calcite, or calcite only, depending on the initial ratio between the anion and calcium monosulfoaluminate hydrate. Chloride ions reacted more slowly and were precipitated as Kuzel's salt, Kuzel's and Friedel's salts, or Friedel's salt only. Rietveld refinement of X-Ray powder diffraction patterns was successfully used to quantify the phase distributions, which were compared to thermodynamic calculations. Moreover, analysing the lattice parameters of Kuzel's salt as a function of its chloride content showed the occurrence of a restricted solid solution towards the sulfate side with general formula 3CaO{center_dot}Al{sub 2}O{sub 3}{center_dot}xCaCl{sub 2}{center_dot}(1 - x)CaSO{sub 4}{center_dot}(12 - 2x){center_dot}H{sub 2}O (0.36 {<=} x {<=} 0.50).

  11. Effect of calcium carbonate saturation of seawater on coral calcification

    USGS Publications Warehouse

    Gattuso, J.-P.; Frankignoulle, M.; Bourge, I.; Romaine, S.; Buddemeier, R.W.

    1998-01-01

    The carbonate chemistry of seawater is usually not considered to be an important factor influencing calcium-carbonate-precipitation by corals because surface seawater is supersaturated with respect to aragonite. Recent reports, however, suggest that it could play a major role in the evolution and biogeography of recent corals. We investigated the calcification rates of five colonies of the zooxanthellate coral Stylophora pistillata in synthetic seawater using the alkalinity anomaly technique. Changes in aragonite saturation from 98% to 585% were obtained by manipulating the calcium concentration. The results show a nonlinear increase in calcification rate as a function of aragonite saturation level. Calcification increases nearly 3-fold when aragonite saturation increases from 98% to 390%, i.e., close to the typical present saturation state of tropical seawater. There is no further increase of calcification at saturation values above this threshold. Preliminary data suggest that another coral species, Acropora sp., displays a similar behaviour. These experimental results suggest: (l) that the rate of calcification does not change significantly within the range of saturation levels corresponding to the last glacial-interglacial cycle, and (2) that it may decrease significantly in the future as a result of the decrease in the saturation level due to anthropogenic release of CO2 into the atmosphere. Experimental studies that control environmental conditions and seawater composition provide unique opportunities to unravel the response of corals to global environmental changes.

  12. Novel protein inhibits in vitro precipitation of calcium carbonate.

    PubMed

    Burgess, S K; Carey, D M; Oxendine, S L

    1992-09-01

    Organic molecules both coexist and interact with inorganic crystal lattices in biomineralizing tissues. Mineral precipitation and crystal morphology are tightly regulated by the actions of these molecules. Polyacrylamide gel electrophoresis studies on water soluble extracts from the cuticle of Callinectes sapidus (Atlantic blue crab) reveal the presence, in unmineralized nascent premolt cuticle, of proteins which are absent in the mineralized postmolt cuticle. In the present studies, homogenates from both premolt and postmolt C. sapidus cuticles have been tested for their effect on the in vitro precipitation of calcium carbonate. The role of protein in this process was determined by heat pretreatment and trypsin pretreatment of the cuticle homogenates prior to the precipitation assay. The results from these experiments indicate that proteins, with molecular weights of approximately 75,000 and between 10,000 and 20,000, concentrated in the C. sapidus premolt cuticle, inhibit calcium carbonate precipitation in vitro. The inhibitory activity of these proteins appears to be a result of specific interactions since trypsin, myoglobin, and ovalbumin are not inhibitory. The presence of lower amounts of these inhibitory proteins in C. sapidus postmolt cuticle may be responsible for the subsequent mineralization of this tissue.

  13. Policy Needs for Carbon Capture & Storage

    NASA Astrophysics Data System (ADS)

    Peridas, G.

    2007-12-01

    Climate change is one of the most pressing environmental problems of our time. The widespread consensus that exists on climate science requires deep cuts in greenhouse gas emissions, on the order of 50-80% globally from current levels. Reducing energy demand, increasing energy efficiency and sourcing our energy from renewable sources will, and should, play a key role in achieving these cuts. Fossil fuels however are abundant, relatively inexpensive, and still make up the backbone of our energy system. Phasing out fossil fuel use will be a gradual process, and is likely to take far longer than the timeframe dictated by climate science for reducing emissions. A reliable way of decarbonizing the use of fossil fuels is needed. Carbon capture and storage (CCS) has already proven to be a technology that can safely and effectively accomplish this task. The technological know-how and the underground capacity exist to store billions of tons of carbon dioxide in mature oil and gas fields, and deep saline formations. Three large international commercial projects and several other applications have proved this, but substantial barriers remain to be overcome before CCS becomes the technology of choice in all major emitting sectors. Government has a significant role to play in surmounting these barriers. Without mandatory limits on greenhouse gas emissions and a price on carbon, CCS is likely to linger in the background. The expected initial carbon price levels and their potential volatility under such a scheme dictates that further policies be used in the early years in order for CCS to be implemented. Such policies could include a new source performance standard for power plants, and a low carbon generation obligation that would relieve first movers by spreading the additional cost of the technology over entire sectors. A tax credit for capturing and permanently sequestering anthropogenic CO2 would aid project economics. Assistance in the form of loan guarantees for components

  14. [Estimation for vegetation carbon storage in Tiantong National Forest Park].

    PubMed

    Guo, Chun-Zi; Wu, Yang-Yang; Ni, Jian

    2014-11-01

    Based on the field investigation and the data combination from literature, vegetation carbon storage, carbon density, and their spatial distribution were examined across six forest community types (Schima superba--Castanopsis fargesii community, S. superba--C. fargesii with C. sclerophylla community, S. superba--C. fargesii with Distylium myricoides community, Illicium lanceolatum--Choerospondias axillaris community, Liquidambar formosana--Pinus massoniana community and Hedyotis auricularia--Phylostachys pubescens community) in Tiantong National Forest Park, Zhejiang Province, by using the allometric biomass models for trees and shrubs. Results showed that: Among the six communities investigated, carbon storage and carbon density were highest in the S. superba--C. fargesii with C. sclerophylla community (storage: 12113.92 Mg C; density: 165.03 Mg C · hm(-2)), but lowest in the I. lanceolatum--C. axillaris community (storage: 680.95 Mg C; density: 101.26 Mg C · hm(-2)). Carbon storage was significantly higher in evergreen trees than in deciduous trees across six communities. Carbon density ranged from 76.08 to 144.95 Mg C · hm(-2), and from 0. 16 to 20. 62 Mg C · hm(-2) for evergreen trees and deciduous trees, respectively. Carbon storage was highest in stems among tree tissues in the tree layer throughout communities. Among vegetation types, evergreen broad-leaved forest had the highest carbon storage (23092.39 Mg C), accounting for 81.7% of the total carbon storage in all forest types, with a car- bon density of 126.17 Mg C · hm(-2). Total carbon storage for all vegetation types in Tiantong National Forest Park was 28254.22 Mg C, and the carbon density was 96.73 Mg C · hm(-2).

  15. Carbon cryogel based nanomaterials for efficient energy storage

    NASA Astrophysics Data System (ADS)

    Feaver, Aaron

    As demand for fossil fuel alternatives intensifies, energy storage will be a growing concern especially for portable power needs such as automobiles and portable electronic devices. In this work Carbon cryogels have been investigated as an energy storage material for applications in super capacitor electrodes as well as both natural gas storage and hydrogen storage. Carbon cryogels can be tuned to achieve a wide range of pore size, pore volume and surface area as well as have their surface chemistry manipulated. It is this flexibility that enables carbon cryogel application in different energy storage approaches including: (1) Super capacitor electrode materials with electrolyte ions adsorbed on the vast surface area of the carbon cryogel network; (2) Adsorbed natural gas storage where 1--2nm pores and extremely high surface area are required; (3) Carbon cryogel/hydride composite hydrogen storage materials where large pore sizes are required to admit metal hydride particles; (4) Carbon cryogel/hydride composite hydrogen storage materials where high surface area is required and surface chemistry must be strictly controlled. The use of carbon cryogels in each of these approaches has shown to have significant benefits over traditional materials used in the field. High surface area carbon cryogels (>2500m2/g) have been produced and show high capacitance, power, and specific energy as well as high gravimetric methane storage capacity. Carbon cryogel have also been produced to accommodate both metal and complex hydride hydrogen storage materials and the decomposition temperature of both materials has been reduced while the complex hydride material released significantly more hydrogen. The implication of these benefits and how they can be achieved will be discussed.

  16. Calcium carbonate nucleation in an alkaline lake surface water, Pyramid Lake, Nevada, USA

    USGS Publications Warehouse

    Reddy, Michael M.; Hoch, Anthony

    2012-01-01

    Calcium concentration and calcite supersaturation (Ω) needed for calcium carbonate nucleation and crystal growth in Pyramid Lake (PL) surface water were determined during August of 1997, 2000, and 2001. PL surface water has Ω values of 10-16. Notwithstanding high Ω, calcium carbonate growth did not occur on aragonite single crystals suspended PL surface water for several months. However, calcium solution addition to PL surface-water samples caused reproducible calcium carbonate mineral nucleation and crystal growth. Mean PL surface-water calcium concentration at nucleation was 2.33 mM (n = 10), a value about nine times higher than the ambient PL surface-water calcium concentration (0.26 mM); mean Ω at nucleation (109 with a standard deviation of 8) is about eight times the PL surface-water Ω. Calcium concentration and Ω regulated the calcium carbonate formation in PL nucleation experiments and surface water. Unfiltered samples nucleated at lower Ω than filtered samples. Calcium concentration and Ω at nucleation for experiments in the presence of added particles were within one standard deviation of the mean for all samples. Calcium carbonate formation rates followed a simple rate expression of the form, rate (mM/min) = A (Ω) + B. The best fit rate equation "Rate (Δ mM/Δ min) = -0.0026 Ω + 0.0175 (r = 0.904, n = 10)" was statistically significant at greater than the 0.01 confidence level and gives, after rearrangement, Ω at zero rate of 6.7. Nucleation in PL surface water and morphology of calcium carbonate particles formed in PL nucleation experiments and in PL surface-water samples suggest crystal growth inhibition by multiple substances present in PL surface water mediates PL calcium carbonate formation, but there is insufficient information to determine the chemical nature of all inhibitors.

  17. Calcium Carbonate Nucleation in an Alkaline Lake Surface Water, Pyramid Lake, Nevada, USA

    USGS Publications Warehouse

    Reddy, M.M.; Hoch, A.

    2012-01-01

    Calcium concentration and calcite supersaturation (??) needed for calcium carbonate nucleation and crystal growth in Pyramid Lake (PL) surface water were determined during August of 1997, 2000, and 2001. PL surface water has ?? values of 10-16. Notwithstanding high ??, calcium carbonate growth did not occur on aragonite single crystals suspended PL surface water for several months. However, calcium solution addition to PL surface-water samples caused reproducible calcium carbonate mineral nucleation and crystal growth. Mean PL surface-water calcium concentration at nucleation was 2.33 mM (n = 10), a value about nine times higher than the ambient PL surface-water calcium concentration (0.26 mM); mean ?? at nucleation (109 with a standard deviation of 8) is about eight times the PL surface-water ??. Calcium concentration and ?? regulated the calcium carbonate formation in PL nucleation experiments and surface water. Unfiltered samples nucleated at lower ?? than filtered samples. Calcium concentration and ?? at nucleation for experiments in the presence of added particles were within one standard deviation of the mean for all samples. Calcium carbonate formation rates followed a simple rate expression of the form, rate (mM/min) = A (??) + B. The best fit rate equation "Rate (?? mM/?? min) = -0.0026 ?? + 0.0175 (r = 0.904, n = 10)" was statistically significant at greater than the 0.01 confidence level and gives, after rearrangement, ?? at zero rate of 6.7. Nucleation in PL surface water and morphology of calcium carbonate particles formed in PL nucleation experiments and in PL surface-water samples suggest crystal growth inhibition by multiple substances present in PL surface water mediates PL calcium carbonate formation, but there is insufficient information to determine the chemical nature of all inhibitors. ?? 2011 U.S. Government.

  18. Effect of strength enhancement of soil treated with environment-friendly calcium carbonate powder.

    PubMed

    Park, Kyungho; Jun, Sangju; Kim, Daehyeon

    2014-01-01

    This study aims to investigate the effects of the strength improvement of soft ground (sand) by producing calcium carbonate powder through microbial reactions. To analyze the cementation effect of calcium carbonate produced through microbial reaction for different weight ratios, four different types of specimens (untreated, calcium carbonate, cement, and calcium carbonate + cement) with different weight ratios (2%, 4%, 6%, and 8%) were produced and cured for a period of 3 days, 7 days, 14 days, 21 days, and 28 days to test them. The uniaxial compression strength of specimens was measured, and the components in the specimen depending on the curing period were analyzed by means of XRD analysis. The result revealed that higher weight ratios and longer curing period contributed to increased strength of calcium carbonate, cement, and calcium carbonate + cement specimens. The calcium carbonate and the calcium carbonate + cement specimens in the same condition showed the tendency of decreased strength approximately 3 times and two times in comparison with the 8% cement specimens cured for 28 days, but the tendency of increased strength was approximately 4 times and 6 times in comparison with the untreated specimen.

  19. Effect of strength enhancement of soil treated with environment-friendly calcium carbonate powder.

    PubMed

    Park, Kyungho; Jun, Sangju; Kim, Daehyeon

    2014-01-01

    This study aims to investigate the effects of the strength improvement of soft ground (sand) by producing calcium carbonate powder through microbial reactions. To analyze the cementation effect of calcium carbonate produced through microbial reaction for different weight ratios, four different types of specimens (untreated, calcium carbonate, cement, and calcium carbonate + cement) with different weight ratios (2%, 4%, 6%, and 8%) were produced and cured for a period of 3 days, 7 days, 14 days, 21 days, and 28 days to test them. The uniaxial compression strength of specimens was measured, and the components in the specimen depending on the curing period were analyzed by means of XRD analysis. The result revealed that higher weight ratios and longer curing period contributed to increased strength of calcium carbonate, cement, and calcium carbonate + cement specimens. The calcium carbonate and the calcium carbonate + cement specimens in the same condition showed the tendency of decreased strength approximately 3 times and two times in comparison with the 8% cement specimens cured for 28 days, but the tendency of increased strength was approximately 4 times and 6 times in comparison with the untreated specimen. PMID:24688401

  20. Calcium absorbability from milk products, an imitation milk, and calcium carbonate

    SciTech Connect

    Recker, R.R.; Bammi, A.; Barger-Lux, M.J.; Heaney, R.P.

    1988-01-01

    Whole milk, chocolate milk, yogurt, imitation milk (prepared from dairy and nondairy products), cheese, and calcium carbonate were labeled with /sup 45/Ca and administered as a series of test meals to 10 healthy postmenopausal women. Carrier Ca content of the test meals was held constant at 250 mg and subjects fasted before each meal. The absorbability of Ca from the six sources was compared by measuring fractional absorption by the double isotope method. The mean absorption values for all six sources were tightly clustered between 21 and 26% and none was significantly different from the others using one-way analysis of variance. We conclude that none of the sources was significantly superior or inferior to the others.

  1. Sodium-Ion Storage in Pyroprotein-Based Carbon Nanoplates.

    PubMed

    Yun, Young Soo; Park, Kyu-Young; Lee, Byoungju; Cho, Se Youn; Park, Young-Uk; Hong, Sung Ju; Kim, Byung Hoon; Gwon, Hyeokjo; Kim, Haegyeom; Lee, Sungho; Park, Yung Woo; Jin, Hyoung-Joon; Kang, Kisuk

    2015-11-18

    Pyroprotein-based carbon nanoplates are fabricated from self-assembled silk proteins as a versatile platform to examine sodium-ion storage characteristics in various carbon environments. It is found that, depending on the local carbon structure, sodium ions are stored via chemi-/physisorption, insertion, or nanoclustering of metallic sodium.

  2. Sociopolitical drivers in the development of deliberate carbon storage

    NASA Astrophysics Data System (ADS)

    Stephens, Jennie C.

    The idea of engineering the storage of carbon released from fossil fuel burning in reservoirs other than the atmosphere has developed in the past 20 years from an obscure idea to an increasingly recognized potential approach that could be an important contributor to stabilizing atmospheric carbon dioxide (CO2) concentrations. Despite the intense application of scientific and technological expertise to the development of options for deliberate carbon storage, nontechnical factors play an important role. This chapter identifies sociopolitical, nontechnical factors that have contributed to the development of ideas and technologies associated with deliberate carbon storage. Broadly, interest in deliberate storage has expanded in response to increasing societal attention to reducing CO2 emissions for climate change mitigation. Specific societal groups, or stakeholders, which have contributed to the recent focus on carbon storage include the fossil fuel industry that has been shifting to a strategy of confronting rather than denying the CO2-climate change connection, a scientific community motivated by an increased sense of urgency of the need to reduce atmospheric CO2 concentrations, the general public with little knowledge about or awareness of carbon storage, and environmental advocacy groups that have demonstrated some divergence in levels of support for deliberate carbon storage. Among the policy mechanisms that have provided incentives for deliberate carbon storage are national accounting of carbon sources and sinks and carbon taxes. Another driver with particular importance in the United States is the political preference of some politicians to support development of advanced technologies for climate change mitigation rather than supporting mandatory CO2 regulations.

  3. Rheological properties of polyolefin composites highly filled with calcium carbonate

    NASA Astrophysics Data System (ADS)

    Nobile, Maria Rossella; Fierro, Annalisa; Jakubowska, Paulina; Sterzynski, Tomasz

    2016-05-01

    In this paper the rheological properties of highly filled polyolefin composites (HFPCs) have been investigated. Calcium carbonate (CaCO3), with stearic acid modified surface, was used as filler. Ternary compounds have been obtained by the inclusion of a CaCO3/polypropylene master batch into the high density polyethylene matrix. The highly filled polyolefin composites with CaCO3 content in the range between 40 and 64 wt% have been prepared in the molten state using a single-screw extruder, the temperature of the extrusion die was set at 230°C. The melt rheological properties of the HFPCs have been extensively investigated both in oscillatory and steady shear flow.

  4. Coexistence of amorphous and crystalline calcium carbonate in skeletal tissues.

    PubMed

    Aizenberg, J; Weiner, S; Addadi, L

    2003-01-01

    We describe a new type of composite skeletal tissues in which calcite and stabilized amorphous calcium carbonate (ACC) coexist in well-defined domains. The organisms that form such structures are widely separated in the animal kingdom phylogenetic tree: calcareous sponges and ascidians. This paper compares the microstructures of their composite skeletal elements: The triradiate spicules from the sponge Clathrina are composed of a core of calcite embedded in a thick layer of ACC and covered by a thin calcitic envelope; the tunic spicules from the ascidian Pyura pachydermatina are composed of a core of ACC enveloped by an insoluble organic sheath and covered by a thick calcitic layer. We compare and contrast the macromolecules associated with different amorphous and crystalline phases and their ability to induce the formation of stabilized ACC in vitro.

  5. Calcium carbonate obstructive urolithiasis in a red kangaroo (Macropus rufus).

    PubMed

    Lindemann, Dana M; Gamble, Kathryn C; Corner, Sarah

    2013-03-01

    A 6-yr-old male red kangaroo (Macropus rufus) presented for a history of inappetance, abnormal behavior, and unconfirmed elimination for 6 hr prior to presentation. Based on abdominal ultrasound, abdominocentesis, and cystocentesis, a presumptive diagnosis of urinary tract obstruction with uroabdomen and hydronephrosis was reached. Abdominal radiographs did not assist in reaching an antemortem diagnosis. Postmortem examination confirmed a urinary bladder rupture secondary to urethral obstruction by a single urethrolith. Bilateral hydronephrosis and hydroureter were identified and determined to be a result of bilateral ureteroliths. Urolith analysis revealed a composition of 100% calcium carbonate. A dietary analysis was performed, implicating an increased Ca:P ratio from a food preparation miscommunication as a contributing factor. Appropriate husbandry changes were made, and mob surveillance procedures were performed, which resolved the urolithiasis risk for the remaining five animals.

  6. Size control and structure features of spherical calcium carbonate particles

    NASA Astrophysics Data System (ADS)

    Trushina, D. B.; Sulyanov, S. N.; Bukreeva, T. V.; Kovalchuk, M. V.

    2015-07-01

    The size of porous spherical calcium carbonate particles obtained by precipitation from a supersaturated solution has been controlled using bovine serum albumin as an organic additive and ethylene glycol and glycerol as cosolvents of the reaction mixture. The structural aspects of the formation of these particles, which affect the possibility of controlling their sizes, are considered. Highly porous vaterite particles with an average size of about 500 nm have been obtained by adding ethylene glycol and glycerol to the reaction mixture and agitation for no less than 30 min. It is shown that particles are formed as a result of the attachment of vaterite nanocrystallites, the shape of which is anisotropic and can be described by a biaxial ellipsoid.

  7. Calcium carbonate antacids alter esophageal motility in heartburn sufferers.

    PubMed

    Rodriguez-Stanley, Sheila; Ahmed, Tanveer; Zubaidi, Sattar; Riley, Susan; Akbarali, Hamid I; Mellow, Mark H; Miner, Philip B

    2004-01-01

    Chewed calcium carbonate (CaCO3) rapidly neutralizes esophageal acid and may prevent reflux, suggesting another mechanism of action independent of acid neutralization. Calcium is essential for muscle tone. Our aim was to determine if luminal calcium released from chewed antacids improved esophageal motor function in heartburn sufferers. Esophageal manometry and acid clearance (swallows and time to raise esophageal pH to 5 after a 15-ml 0.1 N HCl bolus) were performed in 18 heartburn sufferers before and after chewing two Tums EX (1500 mg CaCO3, 600 mg calcium). Subjects with hypertensive esophageal contractions or hypertensive lower esophageal sphincter pressure (LESP) were excluded. Subjects with normal to low LESP were included. Differences between parameters were determined by two-tailed paired t-tests, P < 0.05. Proximal esophageal contractile amplitude was significantly increased after CaCO3 (47.18 vs 52.97 mm Hg; P = 0.02), distal onset velocity was significantly decreased after CaCO3 (4.34 vs 3.71 cm/sec; P = 0.02), and acid clearance was significantly increased 30 min after CaCO3 (20.35 vs 11.7 swallows, [P < 0.005] and 12.19 vs 6.29 min [P < 0.007]). LESP was not altered after CaCO3 (22.70 vs 23.79 mm Hg; P = 0.551), however, LESP increased in 9 of 18 subjects. Depth of LES relaxation, medial and distal esophageal contractile amplitude, and duration of contractions were not altered by CaCO3. CaCO3 did not alter salivary secretion and pH in a subset of these subjects, and CaCO3 with secreted saliva did not neutralize a 15-ml acid bolus. The Ca2+ released after chewing of CaCO3 antacids may be partially responsible for the reduction of heartburn by significantly improving initiation of peristalsis and acid clearance.

  8. Formate oxidation-driven calcium carbonate precipitation by Methylocystis parvus OBBP.

    PubMed

    Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Arvaniti, Eleni Charalampous; Hosseinkhani, Baharak; Ramos, Jose Angel; Rahier, Hubert; Boon, Nico

    2014-08-01

    Microbially induced carbonate precipitation (MICP) applied in the construction industry poses several disadvantages such asammonia release to the air and nitric acid production. An alternative MICP from calcium formate by Methylocystis parvus OBBP is presented here to overcome these disadvantages. To induce calcium carbonate precipitation, M. parvus was incubated at different calcium formate concentrations and starting culture densities. Up to 91.4% ± 1.6% of the initial calcium was precipitated in the methane-amended cultures compared to 35.1% ± 11.9% when methane was not added. Because the bacteria could only utilize methane for growth, higher culture densities and subsequently calcium removals were exhibited in the cultures when methane was added. A higher calcium carbonate precipitate yield was obtained when higher culture densities were used but not necessarily when more calcium formate was added. This was mainly due to salt inhibition of the bacterial activity at a high calcium formate concentration. A maximum 0.67 ± 0.03 g of CaCO3 g of Ca(CHOOH)2(-1) calcium carbonate precipitate yield was obtained when a culture of 10(9) cells ml(-1) and 5 g of calcium formate liter(-)1 were used. Compared to the current strategy employing biogenic urea degradation as the basis for MICP, our approach presents significant improvements in the environmental sustainability of the application in the construction industry.

  9. Formate Oxidation-Driven Calcium Carbonate Precipitation by Methylocystis parvus OBBP

    PubMed Central

    Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Arvaniti, Eleni Charalampous; Hosseinkhani, Baharak; Ramos, Jose Angel; Rahier, Hubert

    2014-01-01

    Microbially induced carbonate precipitation (MICP) applied in the construction industry poses several disadvantages such as ammonia release to the air and nitric acid production. An alternative MICP from calcium formate by Methylocystis parvus OBBP is presented here to overcome these disadvantages. To induce calcium carbonate precipitation, M. parvus was incubated at different calcium formate concentrations and starting culture densities. Up to 91.4% ± 1.6% of the initial calcium was precipitated in the methane-amended cultures compared to 35.1% ± 11.9% when methane was not added. Because the bacteria could only utilize methane for growth, higher culture densities and subsequently calcium removals were exhibited in the cultures when methane was added. A higher calcium carbonate precipitate yield was obtained when higher culture densities were used but not necessarily when more calcium formate was added. This was mainly due to salt inhibition of the bacterial activity at a high calcium formate concentration. A maximum 0.67 ± 0.03 g of CaCO3 g of Ca(CHOOH)2−1 calcium carbonate precipitate yield was obtained when a culture of 109 cells ml−1 and 5 g of calcium formate liter−1 were used. Compared to the current strategy employing biogenic urea degradation as the basis for MICP, our approach presents significant improvements in the environmental sustainability of the application in the construction industry. PMID:24837386

  10. Grain-based activated carbons for natural gas storage.

    PubMed

    Zhang, Tengyan; Walawender, Walter P; Fan, L T

    2010-03-01

    Natural gas has emerged as a potential alternative to gasoline due to the increase in global energy demand and environmental concerns. An investigation was undertaken to explore the technical feasibility of implementing the adsorbed natural gas (ANG) storage in the fuel tanks of motor vehicles with activated carbons from biomass, e.g., sorghum and wheat. The grain-based activated carbons were prepared by chemical activation; the experimental parameters were varied to identify the optimum conditions. The porosity of the resultant activated carbons was evaluated through nitrogen adsorption; and the storage capacity, through methane adsorption. A comparative study was also carried out with commercial activated carbons from charcoal. The highest storage factor attained was 89 for compacted grain-based activated carbons from grain sorghum with a bulk density of 0.65 g/cm(3), and the highest storage factor attained is 106 for compacted commercial activated carbons (Calgon) with a bulk density of 0.70 g/cm(3). The storage factor was found to increase approximately linearly with increasing bulk density and to be independent of the extent of compaction. This implies that the grain-based activated carbons are the ideal candidates for the ANG storage.

  11. Co-precipitation of dissolved organic matter by calcium carbonate in Pyramid Lake, Nevada

    USGS Publications Warehouse

    Leenheer, Jerry A.; Reddy, Michael M.

    2008-01-01

    Our previous research has demonstrated that dissolved organic matter (DOM) influences calcium carbonate mineral formation in surface and ground water. To better understand DOM mediation of carbonate precipitation and DOM co-precipitation and/or incorporation with carbonate minerals, we characterized the content and speciation of DOM in carbonate minerals and in the lake water of Pyramid Lake, Nevada, USA. A 400-gram block of precipitated calcium carbonate from the Pyramid Lake shore was dissolved in 8 liters of 10% acetic acid. Particulate matter not dissolved by acetic acid was removed by centrifugation. DOM from the carbonate rock was fractionated into nine portions using evaporation, dialysis, resin adsorption, and selective precipitations to remove acetic acid and inorganic constituents. The calcium carbonate rock contained 0.23% DOM by weight. This DOM was enriched in polycarboxylic proteinaceous acids and hydroxy-acids in comparison with the present lake water. DOM in lake water was composed of aliphatic, alicyclic polycarboxylic acids. These compound classes were found in previous studies to inhibit calcium carbonate precipitation. DOM fractions from the carbonate rock were 14C-age dated at about 3,100 to 3,500 years before present. The mechanism of DOM co-precipitation and/or physical incorporation in the calcium carbonate is believed to be due to formation of insoluble calcium complexes with polycarboxylic proteinaceous acids and hydroxy-acids that have moderately large stability constants at the alkaline pH of the lake. DOM co-precipitation with calcium carbonate and incorporation in precipitated carbonate minerals removes proteinaceous DOM, but nearly equivalent concentrations of neutral and acidic forms of organic nitrogen in DOM remain in solution. Calcium carbonate precipitation during lime softening pretreatment of drinking water may have practical applications for removal of proteinaceous disinfection by-product precursors.

  12. New insights into the nation's carbon storage potential

    USGS Publications Warehouse

    Warwick, Peter D.; Zhu, Zhi-Liang

    2012-01-01

    Carbon sequestration is a method of securing carbon dioxide (CO2) to prevent its release into the atmosphere, where it contributes to global warming as a greenhouse gas. Geologic storage of CO2 in porous and permeable rocks involves injecting high-pressure CO2 into a subsurface rock unit that has available pore space. Biologic carbon sequestration refers to both natural and anthropogenic processes by which CO2 is removed from the atmosphere and stored as carbon in vegetation, soils, and sediments.

  13. Spectrophotometric measurement of calcium carbonate saturation states in seawater.

    PubMed

    Easley, Regina A; Patsavas, Mark C; Byrne, Robert H; Liu, Xuewu; Feely, Richard A; Mathis, Jeremy T

    2013-02-01

    Measurements of ocean pH and carbonate ion concentrations in the North Pacific and Arctic Oceans were used to determine calcium carbonate saturation states (Ω(CaCO(3))) from spectrophotometric methods alone. Total carbonate ion concentrations, [CO(3)(2-)](T), were for the first time at sea directly measured using Pb(II) UV absorbance spectra. The basis of the method is given by the following: [formula see text] where (CO(3))β(1) is the PbCO(3)(0) formation constant, e(i) are molar absorptivity ratios, and R = (250)A/(234)A (ratio of absorbances measured at 250 and 234 nm). On the basis of shipboard and laboratory Pb(II) data and complementary carbon-system measurements, the experimental parameters were determined to be (25 °C) the following: [formula see text]. The resulting mean difference between the shipboard spectrophotometric and conventional determinations of [CO(3)(2-)](T) was ±2.03 μmol kg(-1). The shipboard analytical precision of the Pb(II) method was ∼1.71 μmol kg(-1) (2.28%). Spectrophotometric [CO(3)(2-)](T) and pH(T) were then combined to calculate Ω(CaCO(3)). For the case of aragonite, 95% of the spectrophotometric aragonite saturation states (Ω(Aspec)) were within ±0.06 of the conventionally calculated values (Ω(Acalc)) when 0.5 ≤ Ω(A) ≤ 2.0. When Ω(A) > 2.0, 95% of the Ω(Aspec) values were within ±0.18 of Ω(Acalc). Our shipboard experience indicates that spectrophotometric determinations of [CO(3)(2-)](T) and Ω(CaCO(3)) are straightforward, fast, and precise. The method yields high-quality measurements of two important, rapidly changing aspects of ocean chemistry and offers capabilities suitable for long-term automated in situ monitoring.

  14. Controlled synthesis of crystalline calcium carbonate aggregates with unusual morphologies involving the phase transformation from amorphous calcium carbonate

    SciTech Connect

    Tang Hua; Yu Jiaguo Zhao Xiufeng

    2009-04-02

    Peanut-shaped CaCO{sub 3} aggregates, featured of two dandelion-like heads built up from rod-like subunits, have been synthesized via a facile precipitation reaction between Na{sub 2}CO{sub 3} and CaCl{sub 2} at ambient temperature in the presence of magnesium ions and ethanol solvent. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The results show that a high magnesium concentration and ethanol solvent are necessary for the formation of the unusual peanut-like aggregates. In addition, a multistep phase transformation process from amorphous calcium carbonate (ACC) to a mixture of ACC and calcite and ultimately to calcite and aragonite was observed in the formation process of the unusual structures. A possible mechanism for the formation of the unusual peanut-shape aggregates has been proposed and discussed.

  15. Carbon Nanotube Films for Energy Storage Applications

    NASA Astrophysics Data System (ADS)

    Kozinda, Alina

    With the rising demands for small, lightweight, and long-lasting portable electronics, the need for energy storage devices with both large power and large energy densities becomes vitally important. From their usage in hybrid electric vehicles to wearable electronics, supercapacitors and rechargeable batteries have been the focus of many previous works. Electrode materials with large specific surface areas can enhance the charging speed and total amount of stored energy. To this end, vertically self-aligned carbon nanotube (CNT) forests are well suited, as they possess outstanding electrical conductivities as well as high mechanical strength and large specific surface areas. In addition, forests of vertically aligned CNTs allow the ions within an electrolyte to pass freely between the individual CNTs from electrode to electrode. In order to minimize the system resistance of the battery or supercapacitor, a thin molybdenum current collector layer is deposited beneath catalyst of the CNT forest, thus ensuring that when the CNT forest grows from its substrate, each CNT has an innate connection to the current collector. This versatile CNT-Mo film architecture is used in this work as both supercapacitor as well as lithium-ion battery electrodes. It is desirable to have energy storage devices of adjustable shapes, such that they may conform to the shrinking form factors of modern portable electronics and mechanically flexible electrodes are an attractive prospect. The CNT-Mo film is shown here to easily release from its growth substrate, after which it may be placed onto a number of surfaces and topographies and densified. Two polymer films, KaptonRTM and Thermanox(TM) , have been used as substrates for the demonstrations of flexible supercapacitor electrodes. Test results show that the attached active CNT-Mo film can withstand bending to at least as large an angle as 180°. The specific capacitance of a 5 mm by 5 mm area electrode in the K2SO 4 aqueous electrolyte with

  16. Conversion of calcium sulphide to calcium carbonate during the process of recovery of elemental sulphur from gypsum waste.

    PubMed

    de Beer, M; Maree, J P; Liebenberg, L; Doucet, F J

    2014-11-01

    The production of elemental sulphur and calcium carbonate (CaCO3) from gypsum waste can be achieved by thermally reducing the waste into calcium sulphide (CaS), which is then subjected to a direct aqueous carbonation step for the generation of hydrogen sulphide (H2S) and CaCO3. H2S can subsequently be converted to elemental sulphur via the commercially available chemical catalytic Claus process. This study investigated the carbonation of CaS by examining both the solution chemistry of the process and the properties of the formed carbonated product. CaS was successfully converted into CaCO3; however, the reaction yielded low-grade carbonate products (i.e. <90 mass% as CaCO3) which comprised a mixture of two CaCO3 polymorphs (calcite and vaterite), as well as trace minerals originating from the starting material. These products could replace the Sappi Enstra CaCO3 (69 mass% CaCO3), a by-product from the paper industry which is used in many full-scale AMD neutralisation plants but is becoming insufficient. The insight gained is now also being used to develop and optimize an indirect aqueous CaS carbonation process for the production of high-grade CaCO3 (i.e. >99 mass% as CaCO3) or precipitated calcium carbonate (PCC).

  17. Hydrogen storage in carbon materials—preliminary results

    NASA Astrophysics Data System (ADS)

    Jörissen, Ludwig; Klos, Holger; Lamp, Peter; Reichenauer, Gudrun; Trapp, Victor

    1998-08-01

    Recent developments aiming at the accelerated commercialization of fuel cells for automotive applications have triggered an intensive research on fuel storage concepts for fuel cell cars. The fuel cell technology currently lacks technically and economically viable hydrogen storage technologies. On-board reforming of gasoline or methanol into hydrogen can only be regarded as an intermediate solution due to the inherently poor energy efficiency of such processes. Hydrogen storage in carbon nanofibers may lead to an efficient solution to the above described problems.

  18. Filled Carbon Nanotubes: Superior Latent Heat Storage Enhancers

    SciTech Connect

    2009-04-01

    This factsheet describes a rstudy whose technical objective is to demonstrate the feasibility of filled carbon nanotubes (CNT) as latent heat storage enhancers, with potential applications as next generation thermal management fluids in diverse applications in industries ranging from high-demand microelectronic cooling, manufacturing, power generation, transportation, to solar energy storage.

  19. Effect of cationic and anionic surfactants on the application of calcium carbonate nanoparticles in paper coating.

    PubMed

    Barhoum, Ahmed; Rahier, Hubert; Abou-Zaied, Ragab Esmail; Rehan, Mohamed; Dufour, Thierry; Hill, Gavin; Dufresne, Alain

    2014-02-26

    Modification of calcium carbonate particles with surfactant significantly improves the properties of the calcium carbonate coating on paper. In this study, unmodified and CTAB (hexadecyltetramethylammonium bromide)- and oleate-modified calcium carbonate nanoparticles were prepared using the wet carbonation technique for paper coating. CTAB (cationic surfactant) and sodium oleate (anionic surfactant) were used to modify the size, morphology, and surface properties of the precipitated nanoparticles. The obtained particles were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, zeta potential measurements, thermal gravimetric analysis (TGA), and transmission electron microscopy (TEM). Coating colors were formulated from the prepared unmodified and modified calcium carbonates and examined by creating a thin coating layer on reference paper. The effect of calcium carbonate particle size and surface modification on paper properties, such as coating thickness, coating weight, surface roughness, air permeability, brightness, whiteness, opacity, and hydrophobicity, were investigated and compared with commercial ground (GCC) calcium carbonate-coated papers. The results show that the obtained calcium carbonate nanoparticles are in the calcite phase. The morphology of the prepared calcium carbonate nanoparticles is rhombohedral, and the average particle diameter is less than 100 nm. Compared to commercial GCC, the use of unmodified and CTAB- and oleate-modified calcium carbonate nanoparticles in paper coating improves the properties of paper. The highest measured paper properties were observed for paper coated with oleate-modifed nanoparticles, where an increase in smoothness (decrease in paper roughness) (+23%), brightness (+1.3%), whiteness (+2.8%), and opacity (+2.3%) and a decrease in air permeability (-26%) was obtained with 25% less coat weight. The water contact angle at a drop age time of 10 min was about 112° for the paper

  20. Characterization of bacteria isolated from palaeoproterozoic metasediments for sequestration of carbon dioxide and formation of calcium carbonate.

    PubMed

    Srivastava, Shaili; Bharti, Randhir K; Thakur, Indu Shekhar

    2015-01-01

    Bacterial community of palaeoproterozoic metasediments was enriched in the chemostat in the presence of different concentrations of NaHCO3. Six bacterial isolates were isolated from the chemostat on nutrient agar plates on the basis of distinct morphology. Denaturing gradient gel electrophoresis (DGGE) proved the presence of six operational taxonomic units (OTUs) at 50 and 100 mM NaHCO3. The OTU was reduced to three and one at enrichment concentration of 150 and 200 mM NaHCO3 respectively. These six isolates were tested for sequestration of carbon dioxide by (14)C metabolic labeling of NaH(14)CO3. Among the six isolates, one of the bacterium showed better potency to fix radiolabeled NaH(14)CO3. The isolate (ISTD04) was identified as Serratia sp. by 16S ribosomal RNA (16S rRNA) sequence analysis and was found to be same as the DGGE OTU sequence at 200-mM NaHCO3 concentration. The bacterium was tested for product formation in form of calcite crystals in presence of 5 % CO2. Scanning electron microscopy (SEM) of product formed by the bacterium revealed defined faceted rhombohedral structure which resembled calcite and vaterite phases of the crystal. Formation of calcium carbonate crystals was further confirmed by Fourier transform infrared (FTIR) spectroscopy as carbonate group showing strong vibration at 1,456 cm(-1). Major calcite phase diffraction peaks were determined by X-ray diffraction (XRD) analysis, and energy-dispersive X-ray (EDX) analysis showed the presence of CaO (72 %) and carbon (18 %). Bacterium use bicarbonate as carbon source for their growth as well as by-product formation in form of calcite shows carbon circulation and storage. PMID:25163561

  1. Characterization of bacteria isolated from palaeoproterozoic metasediments for sequestration of carbon dioxide and formation of calcium carbonate.

    PubMed

    Srivastava, Shaili; Bharti, Randhir K; Thakur, Indu Shekhar

    2015-01-01

    Bacterial community of palaeoproterozoic metasediments was enriched in the chemostat in the presence of different concentrations of NaHCO3. Six bacterial isolates were isolated from the chemostat on nutrient agar plates on the basis of distinct morphology. Denaturing gradient gel electrophoresis (DGGE) proved the presence of six operational taxonomic units (OTUs) at 50 and 100 mM NaHCO3. The OTU was reduced to three and one at enrichment concentration of 150 and 200 mM NaHCO3 respectively. These six isolates were tested for sequestration of carbon dioxide by (14)C metabolic labeling of NaH(14)CO3. Among the six isolates, one of the bacterium showed better potency to fix radiolabeled NaH(14)CO3. The isolate (ISTD04) was identified as Serratia sp. by 16S ribosomal RNA (16S rRNA) sequence analysis and was found to be same as the DGGE OTU sequence at 200-mM NaHCO3 concentration. The bacterium was tested for product formation in form of calcite crystals in presence of 5 % CO2. Scanning electron microscopy (SEM) of product formed by the bacterium revealed defined faceted rhombohedral structure which resembled calcite and vaterite phases of the crystal. Formation of calcium carbonate crystals was further confirmed by Fourier transform infrared (FTIR) spectroscopy as carbonate group showing strong vibration at 1,456 cm(-1). Major calcite phase diffraction peaks were determined by X-ray diffraction (XRD) analysis, and energy-dispersive X-ray (EDX) analysis showed the presence of CaO (72 %) and carbon (18 %). Bacterium use bicarbonate as carbon source for their growth as well as by-product formation in form of calcite shows carbon circulation and storage.

  2. Raman investigation of calcium carbonate bone substitutes and related biomaterials.

    PubMed

    Penel, G; Pottier, E Cau; Leroy, G

    2003-01-01

    The interaction between biomaterials used in surgical procedures and the host bone is not yet perfectly understood. It appears that these problems may have been encountered because of insufficient characterisation of the basic component used in the synthesis of such biomaterials. Calcium carbonate (CaCO3) is interesting for bone filling or regeneration procedures because of its resorbability. The aim of this work is to compare different CaCO3 biomaterials and their basic source with the help of microRaman spectroscopy. Bionacre and Biocoral are analysed. The main bands of carbonate internal modes are observed around 1084-86 and 704-12 cm-1. In the lattice modes region, for both Biocoral and synthetic aragonite, two bands at 206 and 155 cm-1 are observed. The eggshell, oyster shell and synthetic calcite samples exhibit bands at 281 and 155 cm-1. Three bands are present at 280, 206 and 155 cm-1 on the Bionacre sample. The 206 and the 280 cm-1 bands are due to aragonite and calcite forms respectively. Therefore it appears to be a mixture of aragonite and calcite whereas Biocoral is pure aragonite. Additional Raman investigations should be of great interest in evaluating the structural modifications and their influence on the biological behaviour of these biomaterials. Lity index, the percentage of prematurity and of low birth weight are the indices of national health status. PMID:15148877

  3. Record Methane Storage in Monolithic and Powdered Activated Carbons

    NASA Astrophysics Data System (ADS)

    Soo, Yuchoong; Nordwald, E.; Hester, B.; Romanos, J.; Isaacson, B.; Stalla, D.; Moore, D.; Kraus, M.; Burress, J.; Dohnke, E.; Pfeifer, P.

    2010-03-01

    The Alliance for Collaborative Research in Alternative Fuel Technology (ALL-CRAFT) has developed activated carbons from corn cob as adsorbent materials for methane gas storage by physisorption at low pressures. KOH activated carbons were compressed into carbon monolith using chemical binders. High pressure methane isotherms up to 250 bar at room temperature on monolithic and powdered activated carbons were measured gravimetrically and volumetrically. Record methane storage capacities of 250 g CH4/kg carbon and 130 g CH4/liter carbon at 35 bar and 293 K have been achieved. BET surface area, porosity, and pore size distributions were measured from sub-critical nitrogen isotherms. Pore entrances were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A prototype adsorbed natural gas (ANG) tank, loaded with carbon monoliths, was tested in Kansas City.

  4. Carbon Storage in Wetlands and Lakes of the Eastern US

    NASA Technical Reports Server (NTRS)

    Renik, Byrdie; Peteet, Dorothy; Hansen, James E. (Technical Monitor)

    2001-01-01

    Carbon stored underground may participate in a positive feedback with climate warming, as higher temperatures accelerate decomposition reactions and hence CO2 release. Assessing how below-ground carbon storage varies with modern climate and paleoclimate will advance understanding of this feedback in two ways. First, it will estimate the sensitivity of carbon storage to temperature and precipitation changes. Second, it will help quantify the size of carbon stocks available for the feedback, by indicating how current regional climate differences affect carbon storage. Whereas many studies of below-ground carbon storage concentrate on soils, this investigation focuses on the saturated and primarily organic material stored in wetlands and lake sediments. This study surveys research done on organic sediment depth and organic content at 50-100 sites in the eastern U.S., integrating our own research with the work of others. Storage depth is evaluated for sediments from the past 10,000 years, a date reflected in pollen profiles. Organic content is measured chiefly by loss-on-ignition (101). These variables are compared to characteristics of the sites such as latitude, altitude, and vegetation as well as local climate. Preliminary results suggest a strong relationship between latitude and depth of organic material stored over the last 10,000 years, with more accumulation in the northeastern US than the southeastern US. Linking the percent organic matter to actual carbon content is in progress with wetlands from Black Rock Forest and Alpine Swamp.

  5. Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau.

    PubMed

    Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

    2016-01-01

    The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland. PMID:27494253

  6. Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau

    PubMed Central

    Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

    2016-01-01

    The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland. PMID:27494253

  7. Two competitive nucleation mechanisms of calcium carbonate biomineralization in response to surface functionality in low calcium ion concentration solution

    PubMed Central

    Deng, Hua; Wang, Shuo; Wang, Xiumei; Du, Chang; Shen, Xingcan; Wang, Yingjun; Cui, Fuzhai

    2015-01-01

    Four self-assembled monolayer surfaces terminated with –COOH, –OH, –NH2 and –CH3 functional groups are used to direct the biomineralization processes of calcium carbonate (CaCO3) in low Ca2+ concentration, and the mechanism of nucleation and initial crystallization within 12 h was further explored. On −COOH surface, nucleation occurs mainly via ion aggregation mechanism while prenucleation ions clusters may be also involved. On −OH and −NH2 surfaces, however, nucleation forms via calcium carbonate clusters, which aggregate in solution and then are adsorbed onto surfaces following with nucleation of amorphous calcium carbonate (ACC). Furthermore, strongly negative-charged −COOH surface facilitates the direct formation of calcites, and the −OH and −NH2 surfaces determine the formation of vaterites with preferred crystalline orientations. Neither ACC nor crystalline CaCO3 is observed on −CH3 surface. Our findings present a valuable model to understand the CaCO3 biomineralization pathway in natural system where functional groups composition plays a determining role during calcium carbonate crystallization. PMID:26814639

  8. Two competitive nucleation mechanisms of calcium carbonate biomineralization in response to surface functionality in low calcium ion concentration solution.

    PubMed

    Deng, Hua; Wang, Shuo; Wang, Xiumei; Du, Chang; Shen, Xingcan; Wang, Yingjun; Cui, Fuzhai

    2015-09-01

    Four self-assembled monolayer surfaces terminated with -COOH, -OH, -NH2 and -CH3 functional groups are used to direct the biomineralization processes of calcium carbonate (CaCO3) in low Ca(2+) concentration, and the mechanism of nucleation and initial crystallization within 12 h was further explored. On -COOH surface, nucleation occurs mainly via ion aggregation mechanism while prenucleation ions clusters may be also involved. On -OH and -NH2 surfaces, however, nucleation forms via calcium carbonate clusters, which aggregate in solution and then are adsorbed onto surfaces following with nucleation of amorphous calcium carbonate (ACC). Furthermore, strongly negative-charged -COOH surface facilitates the direct formation of calcites, and the -OH and -NH2 surfaces determine the formation of vaterites with preferred crystalline orientations. Neither ACC nor crystalline CaCO3 is observed on -CH3 surface. Our findings present a valuable model to understand the CaCO3 biomineralization pathway in natural system where functional groups composition plays a determining role during calcium carbonate crystallization.

  9. Biomineralization of calcium carbonate polymorphs by the bacterial strains isolated from calcareous sites.

    PubMed

    Dhami, Navdeep Kaur; Reddy, M Sudhakara; Mukherjee, Abhijit

    2013-05-01

    Microbially induced calcium carbonate precipitation (MICCP) is a naturally occurring biological process that has various applications in remediation and restoration of a range of building materials. In the present investigation, five ureolytic bacterial isolates capable of inducing calcium carbonate precipitation were isolated from calcareous soils on the basis of production of urease, carbonic anhydrase, extrapolymeric substances, and biofilm. Bacterial isolates were identified as Bacillus megaterium, B. cereus, B. thuringiensis, B. subtilis, and Lysinibacillus fusiformis based on 16S rRNA analysis. The calcium carbonate polymorphs produced by various bacterial isolates were analyzed by scanning electron microscopy, confocal laser scanning microscopy, X ray diffraction, and Fourier transmission infra red spectroscopy. A strainspecific precipitation of calcium carbonate forms was observed from different bacterial isolates. Based on the type of polymorph precipitated, the technology of MICCP can be applied for remediation of various building materials.

  10. FT-Raman spectroscopic study of calcium-rich and magnesium-rich carbonate minerals.

    PubMed

    Edwards, Howell G M; Villar, Susana E Jorge; Jehlicka, Jan; Munshi, Tasnim

    2005-08-01

    Calcium and magnesium carbonates are important minerals found in sedimentary environments. Although sandstones are the most common rock colonized by endolith organisms, the production of calcium and magnesium carbonates is important in survival strategies of organisms and as a source for the removal of oxalate ions. Extremophile organisms in some situations may convert or destroy carbonates of calcium and magnesium, which gives important information about the conditions under which these organisms can survive. The identification on the surface of Mars of 'White Rock' formations, in Juventae Chasma or Sabaea Terra, as possibly carbonate rocks makes the study of these minerals a prerequisite of remote Martian exploration. Here, we show the protocol for the identification by Raman spectroscopy of different calcium and magnesium carbonates and we present a database of relevance in the search for life, extinct or extant, on Mars; this will be useful for the assessment of data obtained from remote, miniaturized Raman spectrometers now proposed for Mars exploration.

  11. Calcium carbonate corrosivity in an Alaskan inland sea

    NASA Astrophysics Data System (ADS)

    Evans, W.; Mathis, J. T.; Cross, J. N.

    2013-12-01

    Ocean acidification is the hydrogen ion increase caused by the oceanic uptake of anthropogenic CO2, and is a focal point in marine biogeochemistry, in part, because this chemical reaction reduces calcium carbonate (CaCO3) saturation states (Ω) to levels that are corrosive (i.e. Ω ≤ 1) to shell-forming marine organisms. However, other processes can drive CaCO3 corrosivity; specifically, the addition of tidewater glacier melt. To highlight this process, we present carbonate system data collected in May (spring) and September (autumn) starting 2009 through 2012 from Prince William Sound (PWS), a semi-enclosed inland sea located on the south-central coast of Alaska that is ringed with fjords containing tidewater glaciers. Initial sampling in PWS covered limited stations in the western sound, and Ω levels corrosive to aragonite, a form of CaCO3, were observed in association with glacial melt during autumn. Beginning in September 2011, expanded sampling spanned the western and central sound, and included two fjords proximal to tidewater glaciers: Icy Bay and Columbia Bay. The observed conditions in these fjords affected CaCO3 corrosivity in the upper water column (< 50 m) in PWS in two ways: (1) as spring-time formation sites of mode water with near-corrosive Ω levels seen below the mixed layer depth across the sound, and (2) as point sources for surface plumes of glacial melt with corrosive Ω levels (Ω for aragonite and calcite down to 0.60 and 1.02, respectively) and carbon dioxide partial pressures (pCO2) well below atmospheric levels. The cumulative effect of glacial melt is likely responsible for the seasonal widespread reduction of Ω in PWS; however, glacial melt-driven CaCO3 corrosivity is poorly reflected by pCO2 or pHT, indicating that any one of those carbonate parameters alone would inadequately track corrosive conditions in PWS. The unique conditions of the carbonate system in the surface glacial melt plumes enhances atmospheric CO2 uptake, which, if

  12. Poly (vinylsulfonic acid) assisted synthesis of aqueous solution stable vaterite calcium carbonate nanoparticles.

    PubMed

    Nagaraja, Ashvin T; Pradhan, Sulolit; McShane, Michael J

    2014-03-15

    Calcium carbonate nanoparticles of the vaterite polymorph were synthesized by combining CaCl2 and Na2CO3 in the presence of poly (vinylsulfonic acid) (PVSA). By studying the important experimental parameters we found that controlling PVSA concentration, reaction temperature, and order of reagent addition the particle size, monodispersity, and surface charge can be controlled. By increasing PVSA concentration or by decreasing temperature CCNPs with an average size from ≈150 to 500 nm could be produced. We believe the incorporation of PVSA into the reaction plays a dual role to (1) slow down the nucleation rate by sequestering calcium and to (2) stabilize the resulting CCNPs as the vaterite polymorph, preventing surface calcification or aggregation into microparticles. The obtained vaterite nanoparticles were found to maintain their crystal structure and surface charge after storage in aqueous buffer for at least 5 months. The aqueous stable vaterite nanoparticles could be a useful platform for the encapsulation of a large variety of biomolecules for drug delivery or as a sacrificial template toward capsule formation for biosensor applications.

  13. Calcium Carbonate Formation by Genetically Engineered Inorganic Binding Peptides

    NASA Astrophysics Data System (ADS)

    Gresswell, Carolyn Gayle

    Understanding how organisms are capable of forming (synthesize, crystallize, and organize) solid minerals into complex architectures has been a fundamental question of biomimetic materials chemistry and biomineralization for decades. This study utilizes short peptides selected using a cell surface display library for the specific polymorphs of calcium carbonate, i.e., aragonite and calcite, to identify two sets of sequences which can then be used to examine their effects in the formation, crystal structure, morphology of the CaCO3 minerals. A procedure of counter selection, along with fluorescence microscopy (FM) characterization, was adapted to insure that the sequences on the cells were specific to their respective substrate, i.e., aragonite or calcite. From the resulting two sets of sequences selected, five distinct strong binders were identified with a variety of biochemical characteristics and synthesized for further study. Protein derived peptides, using the known sequences of the proteins that are associated with calcite or aragonite, were also designed using a bioinformatics-based similarity analysis of the two sets of binders. In particular, an aragonite binding protein segment, AP7, a protein found in nacre, was chosen for this design and the resulting effects of the designed peptides and the AP7 were examined. Specifically, the binding affinities of the selected and the protein derived peptides off the cells were then tested using FM; these studies resulted in different binding characteristics of the synthesized and cellular bound peptides. Two of the peptides that displayed strong binding on the cells bound to neither of the CaCO 3 substrates and both the high and low similarity protein-derived peptides bound to both polymorphs. However, two of the peptides were found to only bind to their respective polymorph showing; these results are significant in that with this study it is demonstrated that the designed peptides based on experimental library

  14. Waste oil shale ash as a novel source of calcium for precipitated calcium carbonate: carbonation mechanism, modeling, and product characterization.

    PubMed

    Velts, O; Uibu, M; Kallas, J; Kuusik, R

    2011-11-15

    In this paper, a method for converting lime-containing oil shale waste ash into precipitated calcium carbonate (PCC), a valuable commodity is elucidated. The mechanism of ash leachates carbonation was experimentally investigated in a stirred semi-batch barboter-type reactor by varying the CO(2) partial pressure, gas flow rate, and agitation intensity. A consistent set of model equations and physical-chemical parameters is proposed to describe the CaCO(3) precipitation process from oil shale ash leachates of complex composition. The model enables the simulation of reactive species (Ca(2+), CaCO(3), SO(4)(2-), CaSO(4), OH(-), CO(2), HCO(3)(-), H(+), CO(3)(2-)) concentration profiles in the liquid, gas, and solid phases as well as prediction of the PCC formation rate. The presence of CaSO(4) in the product may also be evaluated and used to assess the purity of the PCC product. A detailed characterization of the PCC precipitates crystallized from oil shale ash leachates is also provided. High brightness PCC (containing up to ∼ 96% CaCO(3)) with mean particle sizes ranging from 4 to 10 μm and controllable morphology (such as rhombohedral calcite or coexisting calcite and spherical vaterite phases) was obtained under the conditions studied.

  15. Calcium in diet

    MedlinePlus

    ... of calcium dietary supplements include calcium citrate and calcium carbonate. Calcium citrate is the more expensive form of ... the body on a full or empty stomach. Calcium carbonate is less expensive. It is absorbed better by ...

  16. Calcium-bismuth electrodes for large-scale energy storage (liquid metal batteries)

    SciTech Connect

    Kim, H; Boysen, DA; Ouchi, T; Sadoway, DR

    2013-11-01

    Calcium is an attractive electrode material for use in grid-scale electrochemical energy storage due to its low electronegativity, earth abundance, and low cost. The feasibility of combining a liquid Ca-Bi positive electrode with a molten salt electrolyte for use in liquid metal batteries at 500-700 degrees C was investigated. Exhibiting excellent reversibility up to current densities of 200 mA cm(-2), the calcium bismuth liquid alloy system is a promising positive electrode candidate for liquid metal batteries. The measurement of low self-discharge current suggests that the solubility of calcium metal in molten salt electrolytes can be sufficiently suppressed to yield high coulombic efficiencies >98%. The mechanisms giving rise to Ca-Bi electrode overpotentials were investigated in terms of associated charge transfer and mass transport resistances. The formation of low density Ca11Bi10 intermetallics at the electrode electrolyte interface limited the calcium deposition rate capability of the electrodes; however, the co-deposition of barium into bismuth from barium-containing molten salts suppressed Ca-Bi intermetallic formation thereby improving the discharge capacity. (C) 2013 Elsevier B.V. All rights reserved.

  17. Calcium-bismuth electrodes for large-scale energy storage (liquid metal batteries)

    NASA Astrophysics Data System (ADS)

    Kim, Hojong; Boysen, Dane A.; Ouchi, Takanari; Sadoway, Donald R.

    2013-11-01

    Calcium is an attractive electrode material for use in grid-scale electrochemical energy storage due to its low electronegativity, earth abundance, and low cost. The feasibility of combining a liquid Ca-Bi positive electrode with a molten salt electrolyte for use in liquid metal batteries at 500-700 °C was investigated. Exhibiting excellent reversibility up to current densities of 200 mA cm-2, the calcium-bismuth liquid alloy system is a promising positive electrode candidate for liquid metal batteries. The measurement of low self-discharge current suggests that the solubility of calcium metal in molten salt electrolytes can be sufficiently suppressed to yield high coulombic efficiencies >98%. The mechanisms giving rise to Ca-Bi electrode overpotentials were investigated in terms of associated charge transfer and mass transport resistances. The formation of low density Ca11Bi10 intermetallics at the electrode-electrolyte interface limited the calcium deposition rate capability of the electrodes; however, the co-deposition of barium into bismuth from barium-containing molten salts suppressed Ca-Bi intermetallic formation thereby improving the discharge capacity.

  18. Detection and impacts of leakage from sub-seafloor deep geological carbon dioxide storage

    NASA Astrophysics Data System (ADS)

    Blackford, Jerry; Stahl, Henrik; Bull, Jonathan M.; Bergès, Benoît J. P.; Cevatoglu, Melis; Lichtschlag, Anna; Connelly, Douglas; James, Rachael H.; Kita, Jun; Long, Dave; Naylor, Mark; Shitashima, Kiminori; Smith, Dave; Taylor, Peter; Wright, Ian; Akhurst, Maxine; Chen, Baixin; Gernon, Tom M.; Hauton, Chris; Hayashi, Masatoshi; Kaieda, Hideshi; Leighton, Timothy G.; Sato, Toru; Sayer, Martin D. J.; Suzumura, Masahiro; Tait, Karen; Vardy, Mark E.; White, Paul R.; Widdicombe, Steve

    2014-11-01

    Fossil fuel power generation and other industrial emissions of carbon dioxide are a threat to global climate, yet many economies will remain reliant on these technologies for several decades. Carbon dioxide capture and storage (CCS) in deep geological formations provides an effective option to remove these emissions from the climate system. In many regions storage reservoirs are located offshore, over a kilometre or more below societally important shelf seas. Therefore, concerns about the possibility of leakage and potential environmental impacts, along with economics, have contributed to delaying development of operational CCS. Here we investigate the detectability and environmental impact of leakage from a controlled sub-seabed release of CO2. We show that the biological impact and footprint of this small leak analogue (<1 tonne CO2 d-1) is confined to a few tens of metres. Migration of CO2 through the shallow seabed is influenced by near-surface sediment structure, and by dissolution and re-precipitation of calcium carbonate naturally present in sediments. Results reported here advance the understanding of environmental sensitivity to leakage and identify appropriate monitoring strategies for full-scale carbon storage operations.

  19. Annual Report: Carbon Storage (30 September 2012)

    SciTech Connect

    Strazisar, Brian; Guthrie, George

    2013-11-07

    Activities include laboratory experimentation, field work, and numerical modeling. The work is divided into five theme areas (or first level tasks) that each address a key research need: Flow Properties of Reservoirs and Seals, Fundamental Processes and Properties, Estimates of Storage Potential, Verifying Storage Performance, and Geospatial Data Resources. The project also includes a project management effort which coordinates the activities of all the research teams.

  20. Increasing carbon storage in intact African tropical forests.

    PubMed

    Lewis, Simon L; Lopez-Gonzalez, Gabriela; Sonké, Bonaventure; Affum-Baffoe, Kofi; Baker, Timothy R; Ojo, Lucas O; Phillips, Oliver L; Reitsma, Jan M; White, Lee; Comiskey, James A; Djuikouo K, Marie-Noël; Ewango, Corneille E N; Feldpausch, Ted R; Hamilton, Alan C; Gloor, Manuel; Hart, Terese; Hladik, Annette; Lloyd, Jon; Lovett, Jon C; Makana, Jean-Remy; Malhi, Yadvinder; Mbago, Frank M; Ndangalasi, Henry J; Peacock, Julie; Peh, Kelvin S-H; Sheil, Douglas; Sunderland, Terry; Swaine, Michael D; Taplin, James; Taylor, David; Thomas, Sean C; Votere, Raymond; Wöll, Hannsjörg

    2009-02-19

    The response of terrestrial vegetation to a globally changing environment is central to predictions of future levels of atmospheric carbon dioxide. The role of tropical forests is critical because they are carbon-dense and highly productive. Inventory plots across Amazonia show that old-growth forests have increased in carbon storage over recent decades, but the response of one-third of the world's tropical forests in Africa is largely unknown owing to an absence of spatially extensive observation networks. Here we report data from a ten-country network of long-term monitoring plots in African tropical forests. We find that across 79 plots (163 ha) above-ground carbon storage in live trees increased by 0.63 Mg C ha(-1) yr(-1) between 1968 and 2007 (95% confidence interval (CI), 0.22-0.94; mean interval, 1987-96). Extrapolation to unmeasured forest components (live roots, small trees, necromass) and scaling to the continent implies a total increase in carbon storage in African tropical forest trees of 0.34 Pg C yr(-1) (CI, 0.15-0.43). These reported changes in carbon storage are similar to those reported for Amazonian forests per unit area, providing evidence that increasing carbon storage in old-growth forests is a pan-tropical phenomenon. Indeed, combining all standardized inventory data from this study and from tropical America and Asia together yields a comparable figure of 0.49 Mg C ha(-1) yr(-1) (n = 156; 562 ha; CI, 0.29-0.66; mean interval, 1987-97). This indicates a carbon sink of 1.3 Pg C yr(-1) (CI, 0.8-1.6) across all tropical forests during recent decades. Taxon-specific analyses of African inventory and other data suggest that widespread changes in resource availability, such as increasing atmospheric carbon dioxide concentrations, may be the cause of the increase in carbon stocks, as some theory and models predict.

  1. Carbon Materials for Chemical Capacitive Energy Storage

    SciTech Connect

    Zhai, Yunpu; Dou, Yuqian; Zhao, Dongyuan; Fulvio, Pasquale F.; Mayes, Richard T.; Dai, Sheng

    2011-09-26

    Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.

  2. Carbon materials for chemical capacitive energy storage.

    PubMed

    Zhai, Yunpu; Dou, Yuqian; Zhao, Dongyuan; Fulvio, Pasquale F; Mayes, Richard T; Dai, Sheng

    2011-11-01

    Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed. PMID:21953940

  3. Carbon materials for chemical capacitive energy storage.

    PubMed

    Zhai, Yunpu; Dou, Yuqian; Zhao, Dongyuan; Fulvio, Pasquale F; Mayes, Richard T; Dai, Sheng

    2011-11-01

    Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.

  4. Calcium carbonate corrosivity in an Alaskan inland sea

    NASA Astrophysics Data System (ADS)

    Evans, W.; Mathis, J. T.; Cross, J. N.

    2014-01-01

    Ocean acidification is the hydrogen ion increase caused by the oceanic uptake of anthropogenic CO2, and is a focal point in marine biogeochemistry, in part, because this chemical reaction reduces calcium carbonate (CaCO3) saturation states (Ω) to levels that are corrosive (i.e., Ω ≤ 1) to shell-forming marine organisms. However, other processes can drive CaCO3 corrosivity; specifically, the addition of tidewater glacial melt. Carbonate system data collected in May and September from 2009 through 2012 in Prince William Sound (PWS), a semienclosed inland sea located on the south-central coast of Alaska and ringed with fjords containing tidewater glaciers, reveal the unique impact of glacial melt on CaCO3 corrosivity. Initial limited sampling was expanded in September 2011 to span large portions of the western and central sound, and included two fjords proximal to tidewater glaciers: Icy Bay and Columbia Bay. The observed conditions in these fjords affected CaCO3 corrosivity in the upper water column (< 50 m) in PWS in two ways: (1) as spring-time formation sites of mode water with near-corrosive Ω levels seen below the mixed layer over a portion of the sound, and (2) as point sources for surface plumes of glacial melt with corrosive Ω levels (Ω for aragonite and calcite down to 0.60 and 1.02, respectively) and carbon dioxide partial pressures (pCO2) well below atmospheric levels. CaCO3 corrosivity in glacial melt plumes is poorly reflected by pCO2 or pHT, indicating that either one of these carbonate parameters alone would fail to track Ω in PWS. The unique Ω and pCO2 conditions in the glacial melt plumes enhances atmospheric CO2 uptake, which, if not offset by mixing or primary productivity, would rapidly exacerbate CaCO3 corrosivity in a positive feedback. The cumulative effects of glacial melt and air-sea gas exchange are likely responsible for the seasonal reduction of Ω in PWS, making PWS highly sensitive to increasing atmospheric CO2 and amplified Ca

  5. Calcium carbonate corrosivity in an Alaskan inland sea

    NASA Astrophysics Data System (ADS)

    Evans, W.; Mathis, J. T.; Cross, J. N.

    2013-09-01

    Ocean acidification is the hydrogen ion increase caused by the oceanic uptake of anthropogenic CO2, and is a focal point in marine biogeochemistry, in part, because this chemical reaction reduces calcium carbonate (CaCO3) saturation states (Ω) to levels that are corrosive (i.e. Ω ≤ 1) to shell-forming marine organisms. However, other processes can drive CaCO3 corrosivity; specifically, the addition of tidewater glacial melt. Carbonate system data collected in May and September from 2009 through 2012 in Prince William Sound (PWS), a semi-enclosed inland sea located on the south-central coast of Alaska that is ringed with fjords containing tidewater glaciers, reveal the unique impact of glacial melt on CaCO3 corrosivity. Initial limited sampling was expanded in September 2011 to span large portions of the western and central sound, and included two fjords proximal to tidewater glaciers: Icy Bay and Columbia Bay. The observed conditions in these fjords affected CaCO3 corrosivity in the upper water column (<50 m) in PWS in two ways: (1) as spring-time formation sites of mode water with near-corrosive Ω levels seen below the mixed layer across the sound, and (2) as point sources for surface plumes of glacial melt with corrosive Ω levels (Ω for aragonite and calcite down to 0.60 and 1.02, respectively) and carbon dioxide partial pressures (pCO2) well below atmospheric levels. CaCO3 corrosivity in glacial melt plumes is poorly reflected by pCO2 or pHT, indicating that either one of these carbonate parameters alone would fail to track Ω in PWS. The unique Ω and pCO2 conditions in the glacial melt plumes enhances atmospheric CO2 uptake, which, if not offset by mixing or primary productivity, would rapidly exacerbate CaCO3 corrosivity in a positive feedback. The cumulative effects of glacial melt and air-sea gas exchange are likely responsible for the seasonal widespread reduction of Ω in PWS; making PWS highly sensitive to increasing atmospheric CO2 and amplified

  6. Growth Rate of Calcite Steps as a Function of Aqueous Calcium-to-Carbonate Ratio: Independent Attachment and Detachment of Calcium and Carbonate Ions

    SciTech Connect

    Stack, Andrew G; Grantham, Ms. Meg

    2010-01-01

    Growth rates of monolayer-height steps on the {1014} calcite surface have been measured as a function of the aqueous calcium-to-carbonate ratio. The maximum growth rates of the two common crystallographic orientations were found to deviate from the ideal stoichiometric ratio of 1:1, and dissolution features were observed under supersaturated solutions containing high calcium-to-carbonate ratios. To explain these phenomena, a theory is applied that treats the rates of attachment and detachment of aqueous calcium and carbonate ions separately. The resultant attachment rate constants are 1-3 orders of magnitude smaller than the water exchange rate of the constituent aqueous ions, suggesting that ligand-exchange processes may directly drive attachment. The broader implication is that the saturation state alone is not adequate to fully describe the rates of the multiple, independent reactions that occur on mineral surfaces under these conditions.

  7. Mechanisms of soil carbon storage in experimental grasslands

    NASA Astrophysics Data System (ADS)

    Steinbeiss, S.; Temperton, V. M.; Gleixner, G.

    2007-10-01

    We investigated the fate of root and litter derived carbon into soil organic matter and dissolved organic matter in soil profiles, in order to explain unexpected positive effects of plant diversity on carbon storage. A time series of soil and soil solution samples was investigated at the field site of The Jena Experiment. In addition to the main biodiversity experiment with C3 plants, a C4 species (Amaranthus retroflexus L.) naturally labeled with 13C was grown on an extra plot. Changes in organic carbon concentration in soil and soil solution were combined with stable isotope measurements to follow the fate of plant carbon into the soil and soil solution. A split plot design with plant litter removal versus double litter input simulated differences in biomass input. After 2 years, the no litter and double litter treatment, respectively, showed an increase of 381 g C m-2 and 263 g C m-2 to 20 cm depth, while 71 g C m-2 and 393 g C m-2 were lost between 20 and 30 cm depth. The isotopic label in the top 5 cm indicated that 11 and 15% of soil organic carbon were derived from plant material on the no litter and the double litter treatment, respectively. Without litter, this equals the total amount of carbon newly stored in soil, whereas with double litter this corresponds to twice the amount of stored carbon. Our results indicate that litter input resulted in lower carbon storage and larger carbon losses and consequently accelerated turnover of soil organic carbon. Isotopic evidence showed that inherited soil organic carbon was replaced by fresh plant carbon near the soil surface. Our results suggest that primarily carbon released from soil organic matter, not newly introduced plant organic matter, was transported in the soil solution and contributed to the observed carbon storage in deeper horizons.

  8. Carbon monoxide effects on calcium levels in vascular smooth muscle

    SciTech Connect

    Lin, H.; McGrath, J.J.

    1988-01-01

    Previously the authors showed that carbon monoxide (CO) relaxes vascular smooth muscle in the working heart and thoracic aorta preparation perfused with hemoglobin-free, Krebs-Henseleit (KH) solution. The CO-induced relaxation was not caused by hypoxia, nor was it mediated by adrenergic influences, adenosine, or prostaglandins. In these studies the effect of CO on calcium (Ca/sup + +/) concentrations in vascular smooth muscle was determined using /sup 45/Ca as a tracer. Isolated rat thoracic aorta segments were incubated with /sup 45/Ca and gassed with O/sub 2/, N/sub 2/, or CO for 60 min. Verapamil was used to verify the effectiveness of the test system. Ca/sup + +/ concentrations were 488 /+ -/ 35 and 515 /+ -/ 26 mM/g tissue (X /+ -/ SE) in aortic rings gassed with O/sub 2/ and N/sub 2/, respectively. CO reduced Ca/sup + +/ concentrations significantly (P<0.01) by 29% to 369 /+ -/ 18 mM/g tissue. Verapamil treatment reduced Ca/sup + +/ concentrations by 40% to 314 /+ -/ 23 mM/g tissue. These results suggest that CO relaxes vascular smooth muscle and dilates blood vessels by decreasing Ca/sup + +/ concentrations in vascular smooth muscle.

  9. Cell-specific vacuolar calcium storage mediated by "CAX1" regulates apoplastic calcium concentration, gas exchange, and plant productivity in "Arabidopsis"

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The physiological role and mechanism of nutrient storage within vacuoles of specific cell types is poorly understood. Transcript profiles from "Arabidopsis thaliana" leaf cells differing in calcium concentration ([Ca], epidermis <10 mM versus mesophyll >60 mM) were compared using a microarray screen...

  10. Clinical and histologic evaluation of calcium carbonate in sinus augmentation: a case series.

    PubMed

    Mangano, Carlo; Iaculli, Flavia; Piattelli, Adriano; Mangano, Francesco; Shibli, Jamil Awad; Perrotti, Vittoria; Iezzi, Giovanna

    2014-01-01

    The aim of this case series was a clinical, histologic, and histomorphometric evaluation of calcium carbonate in sinus elevation procedures. Sinus augmentation was performed in the atrophic maxillae of 24 subjects using calcium carbonate. Six months after the regeneration procedures, 68 implants were placed and clinically followed for 1 to 5 years, depending on the placement timing. At the last implant placement procedure, 8 bone cores were harvested and processed for histology. After a 6-month healing period, sinuses grafted with calcium carbonate showed a mean vertical bone gain of 6.93 ± 0.23 mm. The histomorphometric analysis revealed 15% ± 3% residual grafted biomaterial, 28% ± 2% newly formed bone, and 57% ± 2% marrow spaces. The implant survival rate was 98.5%. It can be concluded that calcium carbonate was shown to be clinically suitable for sinus elevation procedures after 1 to 5 years of follow-up and histologically biocompatible and osteoconductive.

  11. Influence of the surfactant nature on the calcium carbonate synthesis in water-in-oil emulsion

    NASA Astrophysics Data System (ADS)

    Szcześ, Aleksandra

    2009-02-01

    Calcium carbonate has been precipitated from water-in-oil emulsions consisting of n-hexane/nonionic surfactant (Brij 30) and its mixture with cationic (DTAB) or anionic surfactant (SDS) to which calcium chloride and sodium carbonate were added. It was found that the surfactant kind and its amount can regulate the size, form and morphology of the precipitated particles. In case of nonionic surfactant the water/surfactant ratio is the most important parameter that allows to obtain small and regular calcium carbonate crystals. Addition of the DTAB results in different morphology of particles having the same crystal form, whereas addition of SDS changes the kind of emulsion from water-in-oil to oil-in-water. Moreover, light transmittance and backscattering light measurements have been used as a method to study the kinetics of calcium carbonate precipitation in emulsion systems.

  12. Crystal growth of calcium carbonate in silk fibroin/sodium alginate hydrogel

    NASA Astrophysics Data System (ADS)

    Ming, Jinfa; Zuo, Baoqi

    2014-01-01

    As known, silk fibroin-like protein plays a pivotal role during the formation of calcium carbonate (CaCO3) crystals in the nacre sheets. Here, we have prepared silk fibroin/sodium alginate nanofiber hydrogels to serve as templates for calcium carbonate mineralization. In this experiment, we report an interesting finding of calcium carbonate crystal growth in the silk fibroin/sodium alginate nanofiber hydrogels by the vapor diffusion method. The experimental results indicate calcium carbonate crystals obtained from nanofiber hydrogels with different proportions of silk fibroin/sodium alginate are mixture of calcite and vaterite with unusual morphologies. Time-dependent growth study was carried out to investigate the crystallization process. It is believed that nanofiber hydrogels play an important role in the process of crystallization. This study would help in understanding the function of organic polymers in natural mineralization, and provide a novel pathway in the design and synthesis of new materials related unique morphology and structure.

  13. Floodplain Organic Carbon Storage in the Central Yukon River Basin

    NASA Astrophysics Data System (ADS)

    Lininger, K.; Wohl, E.

    2014-12-01

    Floodplain storage of organic carbon is an important aspect of the global carbon cycle that is not well understood or quantified. Although it is understood that rivers transport organic carbon to the ocean, little is known about the quantity of stored carbon in boreal floodplains and the influence of fluvial processes on this storage. We present results on total organic carbon (TOC) content within the floodplains of two rivers, the Dall River and Preacher Creek, in the central Yukon River Basin in the Yukon Flats National Wildlife Refuge of Alaska. The results indicate that organic carbon storage is influenced by fluvial disturbance and grain size. The Dall River, which contains a large amount of floodplain carbon, is meandering and incised, with well-developed floodplain soils, a greater percentage of relatively old floodplain surfaces and a slower floodplain turnover time, and finer grain sizes. Preacher Creek stores less TOC, transports coarser grain sizes, and has higher rates of avulsion and floodplain turnover time. Within the floodplain of a particular river, large spatial heterogeneity in TOC content also exists as a function of depositional environment and age and vegetation community of the site. In addition, saturated regions of the floodplains, such as abandoned channels and oxbow lakes, contain more TOC compared to drier floodplain environments. Frozen alluvial soils likely contain carbon that could be released into the environment with melting permafrost, and thus quantifying the organic carbon content in the active layer of floodplain soils could provide insight into the characteristics of the permafrost beneath. The hydrology in these regions is changing due to permafrost melt, and floodplain areas usually saturated could be dried out, causing breakdown and outgassing of carbon stored in previously saturated soils. Ongoing work will result in a first-order estimate of active-layer floodplain carbon storage for the central Yukon River Basin.

  14. Incorporation of strontium in earthworm-secreted calcium carbonate granules produced in strontium-amended and strontium-bearing soil

    NASA Astrophysics Data System (ADS)

    Brinza, Loredana; Quinn, Paul D.; Schofield, Paul F.; Mosselmans, J. Frederick W.; Hodson, Mark E.

    2013-07-01

    This paper investigates the incorporation of Sr into biomineralized calcium carbonate granules secreted by the earthworm Lumbricus terrestris. Experiments were conducted using an agricultural soil amended with Sr(NO3)2 to give concentrations in the range 50-500 mg kg-1 Sr and a naturally Sr-rich, Celestine-bearing soil containing up to 11 000 mg kg-1 Sr. Granule production rates were in the range 0.26-2.3 mgCaCO3 earthworm-1 day-1; they showed no relationship with soil or soil solution Sr concentration but decreased with decreasing pH. Strong relationships exist (r2 ⩾ 0.8, p ⩽ 0.01) between the Sr concentrations and Sr/Ca ratios of the granules and those of the soil, soil solution and earthworms. The highest bulk Sr concentration we recorded in the calcium carbonate granules was 5.1 wt.% Sr whilst electron microprobe analysis recorded spot concentrations of up to 4.3 wt.% Sr. X-ray diffraction and X-ray absorption spectroscopy indicate that the majority of the calcium carbonate is present as Sr-bearing calcite with trace amounts of Sr-bearing vaterite also being present. The granules produced in the Sr-amended soils concentrated Sr relative to Ca from the bulk soil and the earthworms. This suggests that earthworm secreted calcium carbonate may be significant in the cycling of 90Sr released into soils via nuclear accidents or leakage from nuclear waste storage facilities.

  15. How does an amorphous surface influence molecular binding?--ovocleidin-17 and amorphous calcium carbonate.

    PubMed

    Freeman, Colin L; Harding, John H; Quigley, David; Rodger, P Mark

    2015-07-14

    Atomistic molecular dynamics simulations of dehydrated amorphous calcium carbonate interacting with the protein ovocleidin-17 are presented. These simulations demonstrate that the amorphisation of the calcium carbonate surface removes water structure from the surface. This reduction of structure allows the protein to bind with many residues, unlike on crystalline surfaces where binding is strongest when only a few residues are attached to the surface. Basic residues are observed to dominate the binding interactions. The implications for protein control over crystallisation are discussed.

  16. Enhanced lithium ion storage in nanoimprinted carbon

    SciTech Connect

    Wang, Peiqi; Chen, Qian Nataly; Li, Jiangyu; Xie, Shuhong; Liu, Xiaoyan

    2015-07-27

    Disordered carbons processed from polymers have much higher theoretical capacity as lithium ion battery anode than graphite, but they suffer from large irreversible capacity loss and have poor cyclic performance. Here, a simple process to obtain patterned carbon structure from polyvinylpyrrolidone was demonstrated, combining nanoimprint lithography for patterning and three-step heat treatment process for carbonization. The patterned carbon, without any additional binders or conductive fillers, shows remarkably improved cycling performance as Li-ion battery anode, twice as high as the theoretical value of graphite at 98 cycles. Localized electrochemical strain microscopy reveals the enhanced lithium ion activity at the nanoscale, and the control experiments suggest that the enhancement largely originates from the patterned structure, which improves surface reaction while it helps relieving the internal stress during lithium insertion and extraction. This study provides insight on fabricating patterned carbon architecture by rational design for enhanced electrochemical performance.

  17. Enhanced lithium ion storage in nanoimprinted carbon

    NASA Astrophysics Data System (ADS)

    Wang, Peiqi; Chen, Qian Nataly; Xie, Shuhong; Liu, Xiaoyan; Li, Jiangyu

    2015-07-01

    Disordered carbons processed from polymers have much higher theoretical capacity as lithium ion battery anode than graphite, but they suffer from large irreversible capacity loss and have poor cyclic performance. Here, a simple process to obtain patterned carbon structure from polyvinylpyrrolidone was demonstrated, combining nanoimprint lithography for patterning and three-step heat treatment process for carbonization. The patterned carbon, without any additional binders or conductive fillers, shows remarkably improved cycling performance as Li-ion battery anode, twice as high as the theoretical value of graphite at 98 cycles. Localized electrochemical strain microscopy reveals the enhanced lithium ion activity at the nanoscale, and the control experiments suggest that the enhancement largely originates from the patterned structure, which improves surface reaction while it helps relieving the internal stress during lithium insertion and extraction. This study provides insight on fabricating patterned carbon architecture by rational design for enhanced electrochemical performance.

  18. Recent advances in modeling depth distribution of soil carbon storage

    NASA Astrophysics Data System (ADS)

    Mishra, U.; Shu, S.

    2015-12-01

    Depth distribution of soil carbon storage determines the sensitivity of soil carbon to environmental change. We present different approaches that have been used to represent the vertical heterogeneity of soil carbon both in mapping and modeling studies. In digital soil mapping, many studies applied exponential decay functions in soils where carbon concentration has been observed to decline with depth. Recent studies used various forms of spline functions to better represent the vertical distribution of soil carbon along with soil horizons. These studies fitted mathematical functions that described the observations and then interpolated the model coefficients using soil-forming factors and used maps of model coefficients with depth to predict the SOC storage at desired depth intervals. In general, the prediction accuracy decreased with depth and the challenge remains to find appropriate soil-forming factors that determine/explain subsurface soil variation. Models such as Century, RothC, and Terrestrial Ecosystem Model use the exponential depth distribution functions of soil carbon in their model structures. In CLM 4.5 the soil profile is partitioned into 10 layers down to 3.8 m depth and the carbon input from plant roots is assumed to decrease following an exponential function. Not accounting for soil horizons in representing biogeochemistry and the assumption of globally uniform soil depth remain major sources of uncertainty in these models. In this presentation, we will discuss the merits and demerits of using various profile depth distribution functions to represent the vertical heterogeneity of soil carbon storage.

  19. Weathering controls on mechanisms of carbon storage in grassland soils

    USGS Publications Warehouse

    Masiello, C.A.; Chadwick, O.A.; Southon, J.; Torn, M.S.; Harden, J.W.

    2004-01-01

    On a sequence of soils developed under similar vegetation, temperature, and precipitation conditions, but with variations in mineralogical properties, we use organic carbon and 14C inventories to examine mineral protection of soil organic carbon. In these soils, 14C data indicate that the creation of slow-cycling carbon can be modeled as occurring through reaction of organic ligands with Al3+ and Fe3+ cations in the upper horizons, followed by sorption to amorphous inorganic Al compounds at depth. Only one of these processes, the chelation Al3+ and Fe3+ by organic ligands, is linked to large carbon stocks. Organic ligands stabilized by this process traverse the soil column as dissolved organic carbon (both from surface horizons and root exudates). At our moist grassland site, this chelation and transport process is very strongly correlated with the storage and long-term stabilization of soil organic carbon. Our 14C results show that the mechanisms of organic carbon transport and storage at this site follow a classic model previously believed to only be significant in a single soil order (Spodosols), and closely related to the presence of forests. The presence of this process in the grassland Alfisol, Inceptisol, and Mollisol soils of this chronosequence suggests that this process is a more significant control on organic carbon storage than previously thought. Copyright 2004 by the American Geophysical Union.

  20. Weathering controls on mechanisms of carbon storage in grassland soils

    SciTech Connect

    Masiello, C.A.; Chadwick, O.A.; Southon, J.; Torn, M.S.; Harden, J.W.

    2004-09-01

    On a sequence of soils developed under similar vegetation, temperature, and precipitation conditions, but with variations in mineralogical properties, we use organic carbon and 14C inventories to examine mineral protection of soil organic carbon. In these soils, 14C data indicate that the creation of slow-cycling carbon can be modeled as occurring through reaction of organic ligands with Al3+ and Fe3+ cations in the upper horizons, followed by sorption to amorphous inorganic Al compounds at depth. Only one of these processes, the chelation of Al3+ and Fe3+ by organic ligands, is linked to large carbon stocks. Organic ligands stabilized by this process traverse the soil column as dissolved organic carbon (both from surface horizons and root exudates). At our moist grassland site, this chelation and transport process is very strongly correlated with the storage and long-term stabilization of soil organic carbon. Our 14C results show that the mechanisms of organic carbon transport and storage at this site follow a classic model previously believed to only be significant in a single soil order (Spodosols), and closely related to the presence of forests. The presence of this process in the grassland Alfisol, Inceptisol, and Mollisol soils of this chronosequence suggests that this process is a more significant control on organic carbon storage than previously thought.

  1. Concurrent calcium peroxide pretreatment and wet storage of water hyacinth for fermentable sugar production.

    PubMed

    Cheng, Yu-Shen; Chen, Kuan-Yu; Chou, Tzung-Han

    2015-01-01

    In the present study, a novel concurrent process of pretreatment and wet storage was developed and investigated by applying calcium peroxide for preservation and conversion of fresh water hyacinth biomass to fermentable sugars. The effects of CaO2 loading concentration and moisture content on the lignin reduction, carbohydrate preservation and enzymatic saccharification of water hyacinth biomass were evaluated by experimental design using a response surface methodology. The data showed that the concurrent process could conserve 70% carbohydrates and remove 40% lignin from biomass of water hyacinth at the best condition in this study. The enzymatic digestibility and reducing sugar yield from the best condition of concurrent process were around 93% and 325mg/g (dry weight) of fresh biomass, respectively. The result suggested that the concurrent process developed in this work could be a potential alternative to consolidate the pretreatment and storage of aquatic plant biomass for fermentable sugar production. PMID:25461012

  2. High Calcium (~80mol%) Late Stage Carbonate in ALH84001

    NASA Astrophysics Data System (ADS)

    Gildea, K. J.; Holland, G.; Lyon, I. C.; Chatzitheodoridis, E.; Burgess, R.

    2006-03-01

    Brief petrological, chemical and textural description of previously undescribed high Ca late stage carbonate in Martian meteorite ALH84001. This carbonate surrounds Mg rich carbonates and rosette fragments.

  3. Nanowire modified carbon fibers for enhanced electrical energy storage

    NASA Astrophysics Data System (ADS)

    Shuvo, Mohammad Arif Ishtiaque; (Bill) Tseng, Tzu-Liang; Ashiqur Rahaman Khan, Md.; Karim, Hasanul; Morton, Philip; Delfin, Diego; Lin, Yirong

    2013-09-01

    The study of electrochemical super-capacitors has become one of the most attractive topics in both academia and industry as energy storage devices because of their high power density, long life cycles, and high charge/discharge efficiency. Recently, there has been increasing interest in the development of multifunctional structural energy storage devices such as structural super-capacitors for applications in aerospace, automobiles, and portable electronics. These multifunctional structural super-capacitors provide structures combining energy storage and load bearing functionalities, leading to material systems with reduced volume and/or weight. Due to their superior materials properties, carbon fiber composites have been widely used in structural applications for aerospace and automotive industries. Besides, carbon fiber has good electrical conductivity which will provide lower equivalent series resistance; therefore, it can be an excellent candidate for structural energy storage applications. Hence, this paper is focused on performing a pilot study for using nanowire/carbon fiber hybrids as building materials for structural energy storage materials; aiming at enhancing the charge/discharge rate and energy density. This hybrid material combines the high specific surface area of carbon fiber and pseudo-capacitive effect of metal oxide nanowires, which were grown hydrothermally in an aligned fashion on carbon fibers. The aligned nanowire array could provide a higher specific surface area that leads to high electrode-electrolyte contact area thus fast ion diffusion rates. Scanning Electron Microscopy and X-Ray Diffraction measurements are used for the initial characterization of this nanowire/carbon fiber hybrid material system. Electrochemical testing is performed using a potentio-galvanostat. The results show that gold sputtered nanowire carbon fiber hybrid provides 65.9% higher energy density than bare carbon fiber cloth as super-capacitor.

  4. Hydrogen storage capacity of catalytically grown carbon nanofibers.

    PubMed

    Rzepka, Matthias; Bauer, Erich; Reichenauer, Gudrun; Schliermann, Thomas; Bernhardt, Babette; Bohmhammel, Klaus; Henneberg, Eva; Knoll, Uta; Maneck, Heinz-Eberhard; Braue, Wolfgang

    2005-08-11

    In 1996, R. T. K. Baker, and N. M. Rodriguez claimed to have synthesized a new type of carbon nanofiber material capable of storing large amounts of hydrogen at room temperature and pressures above 100 bar, thus making it a powerful candidate for a very efficient energy storage system in mobile applications. Consequently, many scientists all over the world tried to test and verify these findings, however, with partly inconsistent results. We present here for the first time independent hydrogen storage measurements for several types of nanofibers, both synthesized by our group following precisely the specifications given in the literature as well as original samples supplied by Rodriguez and Baker for this study. The hydrogen storage capacities at room temperature and pressures up to 140 bar were quantified independently by gravimetric and volumetric methods, respectively. No significant hydrogen storage capacity has been detected for all carbon nanofibers investigated.

  5. On carbon dioxide storage based on biomineralization strategies.

    PubMed

    Lee, Seung-Woo; Park, Seung-Bin; Jeong, Soon-Kwan; Lim, Kyoung-Soo; Lee, Si-Hyun; Trachtenberg, Michael C

    2010-06-01

    This study focuses on the separation and storage of the global warming greenhouse gas CO(2), and the use of natural biocatalysts in the development of technologies to improve CO(2) storage rates and provide new methods for CO(2) capture. Carbonic anhydrase (CA) has recently been used as a biocatalyst to sequester CO(2) through the conversion of CO(2) to HCO(-) in the mineralization of CaCO(3). Biomimetic CaCO(3) mineralization for carbon capture and storage offers potential as a stable CO(2) capture technology. In this report, we review recent developments in this field and assess disadvantages and improvements in the use of CA in industrial applications. We discuss the contribution that understanding of mechanisms of CO(2) conversion to CO(3)(-) in the formation and regeneration of bivalve shells will make to developments in biomimetic CO(2) storage.

  6. Mechanochemically Activated, Calcium Oxide-Based, Magnesium Oxide-Stabilized Carbon Dioxide Sorbents.

    PubMed

    Kurlov, Alexey; Broda, Marcin; Hosseini, Davood; Mitchell, Sharon J; Pérez-Ramírez, Javier; Müller, Christoph R

    2016-09-01

    Carbon dioxide capture and storage (CCS) is a promising approach to reduce anthropogenic CO2 emissions and mitigate climate change. However, the costs associated with the capture of CO2 using the currently available technology, that is, amine scrubbing, are considered prohibitive. In this context, the so-called calcium looping process, which relies on the reversible carbonation of CaO, is an attractive alternative. The main disadvantage of naturally occurring CaO-based CO2 sorbents, such as limestone, is their rapid deactivation caused by thermal sintering. Here, we report a scalable route based on wet mechanochemical activation to prepare MgO-stabilized, CaO-based CO2 sorbents. We optimized the synthesis conditions through a fundamental understanding of the underlying stabilization mechanism, and the quantity of MgO required to stabilize CaO could be reduced to as little as 15 wt %. This allowed the preparation of CO2 sorbents that exceed the CO2 uptake of the reference limestone by 200 %. PMID:27529608

  7. Mechanochemically Activated, Calcium Oxide-Based, Magnesium Oxide-Stabilized Carbon Dioxide Sorbents.

    PubMed

    Kurlov, Alexey; Broda, Marcin; Hosseini, Davood; Mitchell, Sharon J; Pérez-Ramírez, Javier; Müller, Christoph R

    2016-09-01

    Carbon dioxide capture and storage (CCS) is a promising approach to reduce anthropogenic CO2 emissions and mitigate climate change. However, the costs associated with the capture of CO2 using the currently available technology, that is, amine scrubbing, are considered prohibitive. In this context, the so-called calcium looping process, which relies on the reversible carbonation of CaO, is an attractive alternative. The main disadvantage of naturally occurring CaO-based CO2 sorbents, such as limestone, is their rapid deactivation caused by thermal sintering. Here, we report a scalable route based on wet mechanochemical activation to prepare MgO-stabilized, CaO-based CO2 sorbents. We optimized the synthesis conditions through a fundamental understanding of the underlying stabilization mechanism, and the quantity of MgO required to stabilize CaO could be reduced to as little as 15 wt %. This allowed the preparation of CO2 sorbents that exceed the CO2 uptake of the reference limestone by 200 %.

  8. Efficient in vivo gene transfer by intraperitoneal injection of plasmid DNA and calcium carbonate microflowers in mice.

    PubMed

    Fumoto, Shintaro; Nakajima, Sayuri; Mine, Toyoharu; Yoshikawa, Naoki; Kitahara, Takashi; Sasaki, Hitoshi; Miyamoto, Hirotaka; Nishida, Koyo

    2012-07-01

    Gene transfer to intraperitoneal organs is thought to be a promising approach to treat such conditions as peritoneal fibrosis and peritoneal dissemination of cancers. We previously discovered that simple instillation of naked plasmid DNA (pDNA) onto intraperitoneal organs such as the liver and stomach could effectively transfer foreign genes in mice. In this study, we developed a novel nonviral method to enhance transfection efficiency of naked pDNA to intraperitoneal organs using a calcium carbonate suspension containing pDNA. Using commercially available calcium carbonate, we successfully transfected pDNA to the stomach. Handling of commercially available calcium carbonate, however, was troublesome owing to rapid precipitation and caking. To obtain slowly settling particles of calcium carbonate, we tried to synthesize novel versions of such particles and succeeded in creating flower-shaped particles, named calcium carbonate microflowers. Sedimentation of calcium carbonate microflowers was sufficiently slow for in vivo experiments. Moreover, the transfection efficiency of the suspension of calcium carbonate microflowers to the stomach was more effective than that of commercially available calcium carbonate, especially at low concentrations. Intraperitoneal injection of the suspension of calcium carbonate microflowers containing pDNA greatly enhanced naked pDNA transfer to whole intraperitoneal organs in mice. Furthermore, lactate dehydrogenase activities in intraperitoneal fluid and plasma were not raised by the suspension of calcium carbonate microflowers.

  9. Mountaineer Commerical Scale Carbon Capture and Storage (CCS) Project

    SciTech Connect

    Deanna Gilliland; Matthew Usher

    2011-12-31

    The Final Technical documents all work performed during the award period on the Mountaineer Commercial Scale Carbon Capture & Storage project. This report presents the findings and conclusions produced as a consequence of this work. As identified in the Cooperative Agreement DE-FE0002673, AEP's objective of the Mountaineer Commercial Scale Carbon Capture and Storage (MT CCS II) project is to design, build and operate a commercial scale carbon capture and storage (CCS) system capable of treating a nominal 235 MWe slip stream of flue gas from the outlet duct of the Flue Gas Desulfurization (FGD) system at AEP's Mountaineer Power Plant (Mountaineer Plant), a 1300 MWe coal-fired generating station in New Haven, WV. The CCS system is designed to capture 90% of the CO{sub 2} from the incoming flue gas using the Alstom Chilled Ammonia Process (CAP) and compress, transport, inject and store 1.5 million tonnes per year of the captured CO{sub 2} in deep saline reservoirs. Specific Project Objectives include: (1) Achieve a minimum of 90% carbon capture efficiency during steady-state operations; (2) Demonstrate progress toward capture and storage at less than a 35% increase in cost of electricity (COE); (3) Store CO{sub 2} at a rate of 1.5 million tonnes per year in deep saline reservoirs; and (4) Demonstrate commercial technology readiness of the integrated CO{sub 2} capture and storage system.

  10. National assessment of geologic carbon dioxide storage resources: results

    USGS Publications Warehouse

    ,

    2013-01-01

    In 2012, the U.S. Geological Survey (USGS) completed an assessment of the technically accessible storage resources (TASR) for carbon dioxide (CO2) in geologic formations underlying the onshore and State waters area of the United States. The formations assessed are at least 3,000 feet (914 meters) below the ground surface. The TASR is an estimate of the CO2 storage resource that may be available for CO2 injection and storage that is based on present-day geologic and hydrologic knowledge of the subsurface and current engineering practices. Individual storage assessment units (SAUs) for 36 basins were defined on the basis of geologic and hydrologic characteristics outlined in the assessment methodology of Brennan and others (2010, USGS Open-File Report 2010–1127) and the subsequent methodology modification and implementation documentation of Blondes, Brennan, and others (2013, USGS Open-File Report 2013–1055). The mean national TASR is approximately 3,000 metric gigatons (Gt). The estimate of the TASR includes buoyant trapping storage resources (BSR), where CO2 can be trapped in structural or stratigraphic closures, and residual trapping storage resources, where CO2 can be held in place by capillary pore pressures in areas outside of buoyant traps. The mean total national BSR is 44 Gt. The residual storage resource consists of three injectivity classes based on reservoir permeability: residual trapping class 1 storage resource (R1SR) represents storage in rocks with permeability greater than 1 darcy (D); residual trapping class 2 storage resource (R2SR) represents storage in rocks with moderate permeability, defined as permeability between 1 millidarcy (mD) and 1 D; and residual trapping class 3 storage resource (R3SR) represents storage in rocks with low permeability, defined as permeability less than 1 mD. The mean national storage resources for rocks in residual trapping classes 1, 2, and 3 are 140 Gt, 2,700 Gt, and 130 Gt, respectively. The known recovery

  11. Sulfur Cycling Mediates Calcium Carbonate Geochemistry in Modern Marine Stromatolites

    NASA Technical Reports Server (NTRS)

    Visscher, P. T.; Hoeft, S. E.; Bebout, B. M.; Reid, R. P.

    2004-01-01

    Modem marine stromatolites forming in Highborne Cay, Exumas (Bahamas), contain microbial mats dominated by Schizothrix. Although saturating concentrations of Ca2+ and CO32- exist, microbes mediate CaCO3 precipitation. Cyanobacterial photosynthesis in these stromatolites aids calcium carbonate precipitation by removal of HS+ through CO2 use. Photorespiration and exopolymer production predominantly by oxygenic phototrophs fuel heterotrophic activity: aerobic respiration (approximately 60 umol/sq cm.h) and sulfate reduction (SR; 1.2 umol SO42-/sq cm.h) are the dominant C- consuming processes. Aerobic microbial respiration and the combination of SR and H2S oxidation both facilitate CaCO3 dissolution through H+ production. Aerobic respiration consumes much more C on an hourly basis, but duel fluctuating O2 and H2 depth profiles indicate that overall, SR consumes only slightly less (0.2-0.5) of the primary production. Moreover, due to low O2 concentrations when SR rates are peaking, reoxidation of the H2S formed is incomplete: both thiosulfate and polythionates are formed. The process of complete H2S oxidation yields H+. However, due to a low O2 concentration late in the day and relatively high O2 concentrations early in the following morning, a two-stage oxidation takes place: first, polythionates are formed from H2S, creating alkalinity which coincides with CaCO3 precipitation; secondly, oxidation of polythionates to sulfate yields acidity, resulting in dissolution, etc. Vertical profiles confirmed that the pH peaked late in the afternoon (greater than 8.8) and had the lowest values (less than 7.4) early in the morning. Thus, the effect of this S-cycling through alkalinity production, followed by acidification during H2S oxidation, results in a six times stronger fluctuation in acidity than photosynthesis plus aerobic respiration accomplish. This implies that anaerobic processes play a pivotal role in stromatolite formation.

  12. National assessment of geologic carbon dioxide storage resources: methodology implementation

    USGS Publications Warehouse

    Blondes, Madalyn S.; Brennan, Sean T.; Merrill, Matthew D.; Buursink, Marc L.; Warwick, Peter D.; Cahan, Steven M.; Corum, Margo D.; Cook, Troy A.; Craddock, William H.; DeVera, Christina A.; Drake II, Ronald M.; Drew, Lawrence J.; Freeman, P.A.; Lohr, Celeste D.; Olea, Ricardo A.; Roberts-Ashby, Tina L.; Slucher, Ernie R.; Varela, Brian A.

    2013-01-01

    In response to the 2007 Energy Independence and Security Act, the U.S. Geological Survey (USGS) conducted a national assessment of potential geologic storage resources for carbon dioxide (CO2). Storage of CO2 in subsurface saline formations is one important method to reduce greenhouse gas emissions and curb global climate change. This report provides updates and implementation details of the assessment methodology of Brennan and others (2010, http://pubs.usgs.gov/of/2010/1127/) and describes the probabilistic model used to calculate potential storage resources in subsurface saline formations.

  13. [Variation of forest vegetation carbon storage and carbon sequestration rate in Liaoning Province, Northeast China].

    PubMed

    Zhen, Wei; Huang, Mei; Zhai, Yin-Li; Chen, Ke; Gong, Ya-Zhen

    2014-05-01

    The forest vegetation carbon stock and carbon sequestration rate in Liaoning Province, Northeast China, were predicted by using Canadian carbon balance model (CBM-CFS3) combining with the forest resource data. The future spatio-temporal distribution and trends of vegetation carbon storage, carbon density and carbon sequestration rate were projected, based on the two scenarios, i. e. with or without afforestation. The result suggested that the total forest vegetation carbon storage and carbon density in Liaoning Province in 2005 were 133.94 Tg and 25.08 t x hm(-2), respectively. The vegetation carbon storage in Quercus was the biggest, while in Robinia pseudoacacia was the least. Both Larix olgensis and broad-leaved forests had higher vegetation carbon densities than others, and the vegetation carbon densities of Pinus tabuliformis, Quercus and Robinia pseudoacacia were close to each other. The spatial distribution of forest vegetation carbon density in Liaoning Province showed a decrease trend from east to west. In the eastern forest area, the future increase of vegetation carbon density would be smaller than those in the northern forest area, because most of the forests in the former part were matured or over matured, while most of the forests in the later part were young. Under the scenario of no afforestation, the future increment of total forest vegetation carbon stock in Liaoning Province would increase gradually, and the total carbon sequestration rate would decrease, while they would both increase significantly under the afforestation scenario. Therefore, afforestation plays an important role in increasing vegetation carbon storage, carbon density and carbon sequestration rate.

  14. Effect of a magnetic water treatment on homogeneous and heterogeneous precipitation of calcium carbonate.

    PubMed

    Fathi, Alimi; Mohamed, Tlili; Claude, Gabrielli; Maurin, Georges; Mohamed, Ben Amor

    2006-06-01

    In this paper are reported experimental results on the effect of a magnetic field on the precipitation process of calcium carbonate scale from a hard water. Carbonically pure water was circulated at a constant flow rate in a magnetic field. After this treatment, calcium carbonate precipitation was induced by degassing dissolved carbonic gas. The nucleation time was identified from the variations of the pH and the Ca(2+) concentration. The ratio between homogeneous and heterogeneous nucleation was determined from the measurement of the mass of precipitated calcium carbonate. It is shown that the magnetic treatment increases the total amount of precipitate. This effect depends on the solution pH, the flow rate and the duration of the treatment. In addition, the magnetic treatment modifies the ratio between homogeneous/heterogeneous nucleation. Homogeneous nucleation is promoted by an increasing the pH of water, the flow rate as well as the residence time. The magnetic treatment enhances these effects with a maximum for a 15 min treatment time. It is shown that the presence of calcium carbonate colloid particles is not necessary. It is advanced that the main magnetic effects concern the associations of ionic species which are present in the solution and which are involved in the nucleation process of calcium carbonate precipitation.

  15. Improved integration potential for calcium-phosphate-coated implants after glow-discharge and water-storage.

    PubMed

    Sendax, V I; Baier, R E

    1992-01-01

    Laboratory and clinical data support the conclusion that Radio-Frequency-Glow-Discharge-Treatment (RFGDT) of calcium-phosphate-coated implants can accelerate their functional integration with bone at host sites. In addition to the benefits of surface cleaning and activation associated with RFGDT, a period of water-storage prior to implantation also seems to be beneficial in eluting easily solubilized alkaline calcium components.

  16. Bioinspired synthesis of fluorescent calcium carbonate/carbon dot hybrid composites.

    PubMed

    Guo, Shanshan; Yang, Miao; Chen, Min; Zhang, Juan; Liu, Kang; Ye, Ling; Gu, Wei

    2015-05-01

    Herein, we report a novel method to synthesise fluorescent calcium carbonate/carbon dots (CaCO3/CDs) by simply mixing CaCl2 and Na2CO3 solutions in the presence of CDs. There are two roles of CDs in this easy and cost-effective biomimetic strategy, that is as the template to direct the formation and assembly of calcite nanocrystals into hierarchical spheres with diameters in the range of 200-300 nm and simultaneously as the phosphor to enable the CaCO3 to emit blue fluorescence under UV (365 nm) irradiation with a quantum yield of 56.2%. The CaCO3/CD hybrid composites possessing unique fluorescence properties are potentially useful in various applications.

  17. Can intensive management increase carbon storage in forests

    SciTech Connect

    Schroeder, P.

    1991-01-01

    A possible response to increasing atmospheric CO2 concentration is to attempt to increase the amount of carbon stored in terrestrial vegetation. One approach to increasing the size of the terrestrial carbon sink is to increase the growth of forests by utilizing intensive forest management practices. The paper uses data from the literature and from forest growth and yield models to analyze the impact of three management practices on carbon storage: thinning, fertilization, and control of competing vegetation. Using Douglas-fir (Pseudotsuga menziesii) and loblolly pine (Pinus taeda) as example species, results showed that thinning generally does not increase carbon storage, and may actually cause a decrease. The exception is thinning of very dense young stands.

  18. Global Ocean Storage of Anthropogenic Carbon (GOSAC)

    SciTech Connect

    Orr, J C

    2002-04-02

    GOSAC was an EC-funded project (1998-2001) focused on improving the predictive capacity and accelerating development of global-scale, three-dimensional, ocean carbon-cycle models by means of standardized model evaluation and model intercomparison. Through the EC Environment and Climate Programme, GOSAC supported the participation of seven European modeling groups in the second phase of the larger international effort OCMIP (the Ocean Carbon-Cycle Model Intercomparison Project). OCMIP included model comparison and validation for both CO{sub 2} and other ocean circulation and biogeochemical tracers. Beyond the international OCMIP effort, GOSAC also supported the same EC ocean carbon cycle modeling groups to make simulations to evaluate the efficiency of purposeful sequestration of CO{sub 2} in the ocean. Such sequestration, below the thermocline has been proposed as a strategy to help mitigate the increase of CO{sub 2} in the atmosphere. Some technical and scientific highlights of GOSAC are given.

  19. Carbon coated textiles for flexible energy storage

    SciTech Connect

    Jost, Kristy; Perez, Carlos O; Mcdonough, John; Presser, Volker; Heon, Min; Dion, Genevieve; Gogotsi, Yury

    2011-01-01

    This paper describes a flexible and lightweight fabric supercapacitor electrode as a possible energy source in smart garments. We examined the electrochemical behavior of porous carbon materials impregnated into woven cotton and polyester fabrics using a traditional printmaking technique (screen printing). The porous structure of such fabrics makes them attractive for supercapacitor applications that need porous films for ion transfer between electrodes. We used cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy to study the capacitive behaviour of carbon materials using nontoxic aqueous electrolytes including sodium sulfate and lithium sulfate. Electrodes coated with activated carbon (YP17) and tested at 0.25 A$g1 achieved a high gravimetric and areal capacitance, an average of 85 F$g1 on cotton lawn and polyester microfiber, both corresponding to 0.43 F$cm2.

  20. Carbon coated textiles for flexible energy storage

    SciTech Connect

    Jost, Kristy; Perez, Carlos R.; McDonough, John K.; Presser, Volker; Heon, Min; Dion, Genevieve; Gogotsi, Yury

    2011-10-20

    This paper describes a flexible and lightweight fabric supercapacitor electrode as a possible energy source in smart garments. We examined the electrochemical behavior of porous carbon materials impregnated into woven cotton and polyester fabrics using a traditional printmaking technique (screen printing). The porous structure of such fabrics makes them attractive for supercapacitor applications that need porous films for ion transfer between electrodes. We used cyclic voltammetry, galvanostatic cycling and electrochemical impedance spectroscopy to study the capacitive behaviour of carbon materials using nontoxic aqueous electrolytes including sodium sulfate and lithium sulfate. Electrodes coated with activated carbon (YP17) and tested at ~0.25 A·g⁻¹ achieved a high gravimetric and areal capacitance, an average of 85 F·g⁻¹ on cotton lawn and polyester microfiber, both corresponding to ~0.43 F·cm⁻².

  1. Effect of calcium carbonate combined with calcitonin on hypercalcemia in hemodialysis patients.

    PubMed

    Wei, Yong; Kong, Xiang Lei; Li, Wen Bin; Wang, Zun Song

    2014-12-01

    This short-term study assessed the efficacy and safety of calcium carbonate combined with calcitonin in the treatment of hypercalcemia in hemodialysis patients. Patients (n=64) on hemodialysis for chronic kidney disease for more than 6 months were included based on total serum calcium more than 10.5 mg/dL. All patients were randomized (1:1) to receive calcium carbonate combined with calcitonin (Group I) or lanthanum carbonate (Group II) for 12 weeks. Blood levels of calcium, phosphorus and intact parathyroid hormone (iPTH) were measured every month, bone mass density (BMD) and coronary artery calcium scores (CACS) were measured at 3 months. During the study period, serum calcium decreased from 10.72 ± 0.39 to 10.09 ± 0.28 mg/dL (P < 0.05), serum phosphorus decreased from 6.79 ± 1.05 to 5.46 ± 1.18 mg/dL (P < 0.05), and serum iPTH levels in the Group I and Group II were not significantly different from the baseline. There were no significant differences in CACS in either group. There were no significant differences in the BMD values between Group I and baseline. In Group II, the BMD values at the lumbar spine and femoral neck were significantly lower than those before the trial and significantly lower than the corresponding values of Group I (P<0.05). Calcium carbonate combined with calcitonin and lanthanum carbonate were equally effective in the suppression of hypercalcemia in hemodialysis patients. There were no serious treatment-related adverse events in treatment with calcium carbonate combined with calcitonin.

  2. Effects of switching from calcium carbonate to lanthanum carbonate on bone mineral metabolism in hemodialysis patients.

    PubMed

    Manabe, Rie; Fukami, Kei; Ando, Ryotaro; Sakai, Kazuko; Kusumoto, Takuo; Hazama, Takuma; Adachi, Takeki; Kaida, Yusuke; Nakayama, Yosuke; Ueda, Seiji; Kohno, Keisuke; Wada, Yoshifumi; Yamagishi, Sho-ichi; Okuda, Seiya

    2013-04-01

    Phosphate binders are useful for the treatment of hyperphosphatemia in hemodialysis (HD) patients. This study was performed to examine the effects of switching from calcium carbonate (CC) to lanthanum carbonate (LC) on bone mineral metabolism and inflammatory markers in HD patients. We conducted 29 stable HD patients receiving CC, which was replaced by LC and followed-up for 12 weeks. Patients underwent determinants of blood chemistries such as serum calcium (Ca), phosphorus, parathyroid hormone (PTH) and vitamin D status, and interleukin-6 (IL-6) mRNA levels in whole blood cells were evaluated by real-time PCR just before and after the treatment with LC. Corrected Ca [corrected] levels were significantly reduced, but serum phosphorus levels (P levels) were unchanged after LC treatment. Switching to LC increased whole-PTH, osteocalcin, 1,25(OH)(2) D(3) levels and 1,25(OH)(2) D(3)/25(OH)D(3) ratio. 1,25(OH)(2) D(3)/25(OH)D(3) ratio was negatively correlated with HD duration. Furthermore, whole blood cell IL-6 mRNA levels were significantly reduced by LC treatment. We provided that the switching from CC to LC improved Ca overload and ameliorated vitamin D and inflammatory status in HD patients. These observations suggest that LC may play a protective role for the progression of atherosclerosis and vascular calcification in these patients.

  3. Calcium

    MedlinePlus

    ... milligrams) of calcium each day. Get it from: Dairy products. Low-fat milk, yogurt, cheese, and cottage ... lactase that helps digest the sugar (lactose) in dairy products, and may have gas, bloating, cramps, or ...

  4. Calcium

    MedlinePlus

    ... supplements and fortified foods include gluconate, lactate, and phosphate. Calcium absorption is best when a person consumes ... also interfere with the body's ability to absorb iron and zinc, but this effect is not well ...

  5. Preparation of pure calcium carbonate by mineral carbonation using industrial byproduct FGD gypsum

    NASA Astrophysics Data System (ADS)

    Song, K.; Kim, W.; Bang, J. H.; Park, S.; Jeon, C. W.

    2015-12-01

    Mineral carbonation is one of the geological approaches for the sequestration of anthropogenic CO2 gas. Its concept is based on the natural weathering processes in which silicate minerals containing divalent cations such as Ca or Mg are carbonated to CaCO3 or MgCO3 in the reaction with CO2gas. Raw materials for the mineral carbonation have been extended to various industrial solid wastes such as steel slag, ashes, or FGD (flue gas desulfurization) gypsum which are rich in divalent cations. These materials have economic advantages when they are produced in CO2 emission sites. Flue gas desulfurization (FGD) gypsum is such a byproduct obtained in at coal-fired power plants. Recently, we carried out a research on the direct mineral carbonation of FGD gypsum for CO2sequestration. It showed high carbonation reactivity under ambient conditions and the process can be described as follows: CaSO4·2H2O + CO2(g) + 2NH4OH(aq) → CaCO3(s) + (NH4)2SO4(aq) (1) At the early stage of the process, calcium carbonate (CaCO3) exists as a dissolved ion pair during the induction period. High-purity CaCO3 could be precipitated from dissolved calcium carbonate solution extracted during the induction period. The effect of experimental parameters on pure CaCO3 was evaluated: CO2 flow rate (1-3 L/min), ammonia content (4-12%), and solid-to-liquid (S/L) ratio (5-300 g/L). FE-SEM (field-emission scanning electron microscopy) and XRD (X-ray diffraction) study revealed that the precipitated CaCO3 was round-shaped vaterite crystals. The induction time was inversely proportional to the CO2 flow rate and the yield for pure CaCO3 increased with the ammonia content. The formation efficiency for pure CaCO3 decreased with S/L (solid/liquid) ratio. It was 90% (mol/mol) when the S/L ratio was 5 g/L. However, S/L ratio didn't affect the maximum solubility limit of dissolved CaCO3.

  6. Practical modeling approaches for geological storage of carbon dioxide.

    PubMed

    Celia, Michael A; Nordbotten, Jan M

    2009-01-01

    The relentless increase of anthropogenic carbon dioxide emissions and the associated concerns about climate change have motivated new ideas about carbon-constrained energy production. One technological approach to control carbon dioxide emissions is carbon capture and storage, or CCS. The underlying idea of CCS is to capture the carbon before it emitted to the atmosphere and store it somewhere other than the atmosphere. Currently, the most attractive option for large-scale storage is in deep geological formations, including deep saline aquifers. Many physical and chemical processes can affect the fate of the injected CO2, with the overall mathematical description of the complete system becoming very complex. Our approach to the problem has been to reduce complexity as much as possible, so that we can focus on the few truly important questions about the injected CO2, most of which involve leakage out of the injection formation. Toward this end, we have established a set of simplifying assumptions that allow us to derive simplified models, which can be solved numerically or, for the most simplified cases, analytically. These simplified models allow calculation of solutions to large-scale injection and leakage problems in ways that traditional multicomponent multiphase simulators cannot. Such simplified models provide important tools for system analysis, screening calculations, and overall risk-assessment calculations. We believe this is a practical and important approach to model geological storage of carbon dioxide. It also serves as an example of how complex systems can be simplified while retaining the essential physics of the problem.

  7. Impacts of Geological Variability on Carbon Storage Potential

    NASA Astrophysics Data System (ADS)

    Eccles, Jordan Kaelin

    The changes to the environment caused by anthropogenic climate change pose major challenges for energy production in the next century. Carbon Capture and Storage (CCS) is a group of technologies that would permit the continued use of carbon-intense fuels such as coal for energy production while avoiding further impact on the global climate system. The mechanism most often proposed for storage is injection of CO2 below the surface of the Earth in geological media, with the most promising option for CO2 reservoirs being deep saline aquifers (DSA's). Unlike oil and gas reservoirs, deep saline aquifers are poorly characterized and the variability in their properties is large enough to have a high impact on the overall physical and economic viability of CCS. Storage in saline aquifers is likely to be a very high-capacity resource, but its economic viability is almost unknown. We consider the impact of geological variability on the total viability of the CO 2 storage system from several perspectives. First, we examine the theoretical range of costs of storage by coupling a physical and economic model of CO 2 storage with a range of possible geological settings. With the relevant properties of rock extending over several orders of magnitude, it is not surprising that we find costs and storage potential ranging over several orders of magnitude. Second, we use georeferenced data to evaluate the spatial distribution of cost and capacity. When paired together to build a marginal abatement cost curve (MACC), this cost and capacity data indicates that low cost and high capacity are collocated; storage in these promising areas is likely to be quite viable but may not be available to all CO2 sources. However, when we continue to explore the impact of geological variability on realistic, commercial-scale site sizes by invoking capacity and pressure management constraints, we find that the distribution costs and footprints of these sites may be prohibitively high. The combination

  8. National assessment of geologic carbon dioxide storage resources: data

    USGS Publications Warehouse

    ,

    2013-01-01

    In 2012, the U.S. Geological Survey (USGS) completed the national assessment of geologic carbon dioxide storage resources. Its data and results are reported in three publications: the assessment data publication (this report), the assessment results publication (U.S. Geological Survey Geologic Carbon Dioxide Storage Resources Assessment Team, 2013a, USGS Circular 1386), and the assessment summary publication (U.S. Geological Survey Geologic Carbon Dioxide Storage Resources Assessment Team, 2013b, USGS Fact Sheet 2013–3020). This data publication supports the results publication and contains (1) individual storage assessment unit (SAU) input data forms with all input parameters and details on the allocation of the SAU surface land area by State and general land-ownership category; (2) figures representing the distribution of all storage classes for each SAU; (3) a table containing most input data and assessment result values for each SAU; and (4) a pairwise correlation matrix specifying geological and methodological dependencies between SAUs that are needed for aggregation of results.

  9. Effects of calcium carbonate and hydroxyapatite on zinc and iron retention in postmenopausal women

    SciTech Connect

    Dawson-Hughes, B.; Seligson, F.H.; Hughes, V.A.

    1986-07-01

    We measured the effect of calcium carbonate and hydroxyapatite on whole-body retention of zinc-65 in 11 and iron-59 in 13 healthy, postmenopausal women. In a single-blind, controlled, crossover study, each subject, on three occasions, ingested a standard test meal supplemented with iron-59 or zinc-65 and capsules containing placebo or 500 mg elemental calcium as calcium carbonate or hydroxyapatite. Whole-body countings were performed prior to, 30 min after, and 2 wk after each meal. Mean (SEM) zinc retention was 18.1 +/- 1.0% with placebo (control) and did not vary significantly with calcium carbonate (110.0 +/- 8.6% of control) or hydroxyapatite (106.0 +/- 7.9% of control). Iron retention, 6.3 +/- 2.0% with placebo, was significantly reduced with both calcium carbonate (43.3 +/- 8.8% of control, p = 0.002) and hydroxyapatite (45.9 +/- 10.0% of control, p = 0.003). Iron absorption may be significantly reduced when calcium supplements are taken with meals.

  10. Carbon foams for energy storage devices

    DOEpatents

    Kaschmitter, James L.; Mayer, Steven T.; Pekala, Richard W.

    1996-01-01

    A high energy density capacitor incorporating a variety of carbon foam electrodes is described. The foams, derived from the pyrolysis of resorcinol-formaldehyde and related polymers, are high density (0.1 g/cc-1.0 g/cc) electrically conductive and have high surface areas (400 m.sup.2 /g-1000 m.sup.2 /g). Capacitances on the order of several tens of farad per gram of electrode are achieved.

  11. Carbon foams for energy storage devices

    DOEpatents

    Kaschmitter, J.L.; Mayer, S.T.; Pekala, R.W.

    1996-06-25

    A high energy density capacitor incorporating a variety of carbon foam electrodes is described. The foams, derived from the pyrolysis of resorcinol-formaldehyde and related polymers, are high density (0.1 g/cc--1.0 g/cc) electrically conductive and have high surface areas (400 m{sup 2}/g-1000 m{sup 2}/g). Capacitances on the order of several tens of farad per gram of electrode are achieved. 9 figs.

  12. Carbon Honeycomb High Capacity Storage for Gaseous and Liquid Species

    NASA Astrophysics Data System (ADS)

    Krainyukova, Nina V.; Zubarev, Evgeniy N.

    2016-02-01

    We report an exceptionally stable honeycomb carbon allotrope obtained by deposition of vacuum-sublimated graphite. The allotrope structures are derived from our low temperature electron diffraction and electron microscopy data. These structures can be both periodic and random and are built exclusively from s p2 -bonded carbon atoms, and may be considered as three-dimensional graphene. They demonstrate high levels of physical absorption of various gases unattainable in other carbon forms such as fullerites or nanotubes. These honeycomb structures can be used not only for storage of various gases and liquids but also as a matrix for new composites.

  13. Doping of carbon foams for use in energy storage devices

    DOEpatents

    Mayer, S.T.; Pekala, R.W.; Morrison, R.L.; Kaschmitter, J.L.

    1994-10-25

    A polymeric foam precursor, wetted with phosphoric acid, is pyrolyzed in an inert atmosphere to produce an open-cell doped carbon foam, which is utilized as a lithium intercalation anode in a secondary, organic electrolyte battery. Tests were conducted in a cell containing an organic electrolyte and using lithium metal counter and reference electrodes, with the anode located there between. Results after charge and discharge cycling, for a total of 6 cycles, indicated a substantial increase in the energy storage capability of the phosphorus doped carbon foam relative to the undoped carbon foam, when used as a rechargeable lithium ion battery. 3 figs.

  14. Doping of carbon foams for use in energy storage devices

    DOEpatents

    Mayer, Steven T.; Pekala, Richard W.; Morrison, Robert L.; Kaschmitter, James L.

    1994-01-01

    A polymeric foam precursor, wetted with phosphoric acid, is pyrolyzed in an inert atmosphere to produce an open-cell doped carbon foam, which is utilized as a lithium intercalation anode in a secondary, organic electrolyte battery. Tests were conducted in a cell containing an organic electrolyte and using lithium metal counter and reference electrodes, with the anode located therebetween. Results after charge and discharge cycling, for a total of 6 cycles, indicated a substantial increase in the energy storage capability of the phosphorus doped carbon foam relative to the undoped carbon foam, when used as a rechargeable lithium ion battery.

  15. pH control in biological systems using calcium carbonate.

    PubMed

    Salek, S S; van Turnhout, A G; Kleerebezem, R; van Loosdrecht, M C M

    2015-05-01

    Due to its abundance, calcium carbonate (CaCO3) has high potentials as a source of alkalinity for biotechnological applications. The application of CaCO3 in biological systems as neutralizing agent is, however, limited due to potential difficulties in controlling the pH. The objective of the present study was to determine the dominant processes that control the pH in an acid-forming microbial process in the presence of CaCO3. To achieve that, a mathematical model was made with a minimum set of kinetically controlled and equilibrium reactions that was able to reproduce the experimental data of a batch fermentation experiment using finely powdered CaCO3. In the model, thermodynamic equilibrium was assumed for all speciation, complexation and precipitation reactions whereas, rate limited reactions were included for the biological fatty acid production, the mass transfer of CO2 from the liquid phase to the gas phase and the convective transport of CO2 out of the gas phase. The estimated pH-pattern strongly resembled the measured pH, suggesting that the chosen set of kinetically controlled and equilibrium reactions were establishing the experimental pH. A detailed analysis of the reaction system with the aid of the model revealed that the pH establishment was most sensitive to four factors: the mass transfer rate of CO2 to the gas phase, the biological acid production rate, the partial pressure of CO2 and the Ca(+2) concentration in the solution. Individual influences of these factors on the pH were investigated by extrapolating the model to a continuously stirred-tank reactor (CSTR) case. This case study indicates how the pH of a commonly used continuous biotechnological process could be manipulated and adjusted by altering these four factors. Achieving a better insight of the processes controlling the pH of a biological system using CaCO3 as its neutralizing agent can result in broader applications of CaCO3 in biotechnological industries.

  16. Drug loading into porous calcium carbonate microparticles by solvent evaporation.

    PubMed

    Preisig, Daniel; Haid, David; Varum, Felipe J O; Bravo, Roberto; Alles, Rainer; Huwyler, Jörg; Puchkov, Maxim

    2014-08-01

    Drug loading into porous carriers may improve drug release of poorly water-soluble drugs. However, the widely used impregnation method based on adsorption lacks reproducibility and efficiency for certain compounds. The aim of this study was to evaluate a drug-loading method based on solvent evaporation and crystallization, and to investigate the underlying drug-loading mechanisms. Functionalized calcium carbonate (FCC) microparticles and four drugs with different solubility and permeability properties were selected as model substances to investigate drug loading. Ibuprofen, nifedipine, losartan potassium, and metronidazole benzoate were dissolved in acetone or methanol. After dispersion of FCC, the solvent was removed under reduced pressure. For each model drug, a series of drug loads were produced ranging from 25% to 50% (w/w) in steps of 5% (w/w). Loading efficiency was qualitatively analyzed by scanning electron microscopy (SEM) using the presence of agglomerates and drug crystals as indicators of poor loading efficiency. The particles were further characterized by mercury porosimetry, specific surface area measurements, differential scanning calorimetry, and USP2 dissolution. Drug concentration was determined by HPLC. FCC-drug mixtures containing equivalent drug fractions but without specific loading strategy served as reference samples. SEM analysis revealed high efficiency of pore filling up to a drug load of 40% (w/w). Above this, agglomerates and separate crystals were significantly increased, indicating that the maximum capacity of drug loading was reached. Intraparticle porosity and specific surface area were decreased after drug loading because of pore filling and crystallization on the pore surface. HPLC quantification of drugs taken up by FCC showed only minor drug loss. Dissolution rate of FCC loaded with metronidazole benzoate and nifedipine was faster than the corresponding FCC-drug mixtures, mainly due to surface enlargement, because only small

  17. National assessment of geologic carbon dioxide storage resources: summary

    USGS Publications Warehouse

    ,

    2013-01-01

    The U.S. Geological Survey (USGS) recently completed an evaluation of the technically accessible storage resource (TASR) for carbon dioxide (CO2) for 36 sedimentary basins in the onshore areas and State waters of the United States. The TASR is an estimate of the geologic storage resource that may be available for CO2 injection and storage and is based on current geologic and hydrologic knowledge of the subsurface and current engineering practices. By using a geology-based probabilistic assessment methodology, the USGS assessment team members obtained a mean estimate of approximately 3,000 metric gigatons (Gt) of subsurface CO2 storage capacity that is technically accessible below onshore areas and State waters; this amount is more than 500 times the 2011 annual U.S. energy-related CO2 emissions of 5.5 Gt (U.S. Energy Information Administration, 2012, http://www.eia.gov/environment/emissions/carbon/). In 2007, the Energy Independence and Security Act (Public Law 110–140) directed the U.S. Geological Survey to conduct a national assessment of geologic storage resources for CO2 in consultation with the U.S. Environmental Protection Agency, the U.S. Department of Energy, and State geological surveys. The USGS developed a methodology to estimate storage resource potential in geologic formations in the United States (Burruss and others, 2009, USGS Open-File Report (OFR) 2009–1035; Brennan and others, 2010, USGS OFR 2010–1127; Blondes, Brennan, and others, 2013, USGS OFR 2013–1055). In 2012, the USGS completed the assessment, and the results are summarized in this Fact Sheet and are provided in more detail in companion reports (U.S. Geological Survey Geologic Carbon Dioxide Storage Resources Assessment Team, 2013a,b; see related reports at right). The goal of this project was to conduct an initial assessment of storage capacity on a regional basis, and results are not intended for use in the evaluation of specific sites for potential CO2 storage. The national

  18. The effect of pigeon yolk sac fluid on the growth behavior of calcium carbonate crystals.

    PubMed

    Song, Juan; Cheng, Haixia; Shen, Xinyu; Tong, Hua

    2015-03-01

    Previous experiments have proved that thermodynamically unstable calcium carbonate vaterite can exist for long periods in the yolk sac of a pigeon embryo. The aim of this article was to demonstrate the effect of in vitro mineralization of yolk sac fluid on calcium carbonate by direct precipitation. Experiments were conducted using pigeon yolk sac fluid and using lecithin extracted from pigeon yolk sac fluid as a control to investigate the regulating effects of the organic components in the embryo on the formation of the calcium carbonate precipitate. Multiple characterization methods were employed to study the various morphological patterns, sizes, crystal growth, and crystal phase transformations of the calcium carbonate precipitates as regulated by the yolk sac fluid extracted at different stages of incubation. The experimental results demonstrate that as the incubation proceeds towards the later stages, the composition and environmental features of the yolk sac fluid become more favorable for the formation of relatively unstable calcium carbonate phases with high energies of the vaterite state. The experiments conducted with extracted lecithin as the template for crystal growth yielded similar results. A large amount of organic molecules with polar functional groups carried by the yolk sac fluid have strong effects and can both initially induce the crystallization and regulate the aggregation of calcium carbonate. Furthermore, this regulation process is found to be closely related to the lecithin contained in yolk sac fluid. These observations confirm the changes in yolk sac fluid composition during incubation have significant effects on the production of vaterite, which implicates the calcium transport during embryo growth.

  19. The skeletal organic matrix from Mediterranean coral Balanophyllia europaea influences calcium carbonate precipitation.

    PubMed

    Goffredo, Stefano; Vergni, Patrizia; Reggi, Michela; Caroselli, Erik; Sparla, Francesca; Levy, Oren; Dubinsky, Zvy; Falini, Giuseppe

    2011-01-01

    Scleractinian coral skeletons are made mainly of calcium carbonate in the form of aragonite. The mineral deposition occurs in a biological confined environment, but it is still a theme of discussion to what extent the calcification occurs under biological or environmental control. Hence, the shape, size and organization of skeletal crystals from the cellular level through the colony architecture, were attributed to factors as diverse as mineral supersaturation levels and organic mediation of crystal growth. The skeleton contains an intra-skeletal organic matrix (OM) of which only the water soluble component was chemically and physically characterized. In this work that OM from the skeleton of the Balanophyllia europaea, a solitary scleractinian coral endemic to the Mediterranean Sea, is studied in vitro with the aim of understanding its role in the mineralization of calcium carbonate. Mineralization of calcium carbonate was conducted by overgrowth experiments on coral skeleton and in calcium chloride solutions containing different ratios of water soluble and/or insoluble OM and of magnesium ions. The precipitates were characterized by diffractometric, spectroscopic and microscopic techniques. The results showed that both soluble and insoluble OM components influence calcium carbonate precipitation and that the effect is enhanced by their co-presence. The role of magnesium ions is also affected by the presence of the OM components. Thus, in vitro, OM influences calcium carbonate crystal morphology, aggregation and polymorphism as a function of its composition and of the content of magnesium ions in the precipitation media. This research, although does not resolve the controversy between environmental or biological control on the deposition of calcium carbonate in corals, sheds a light on the role of OM, which appears mediated by the presence of magnesium ions. PMID:21799830

  20. DEVELOPMENT OF DOPED NANOPOROUS CARBONS FOR HYDROGEN STORAGE

    SciTech Connect

    Lueking, Angela D.; Li, Qixiu; Badding, John V.; Fonseca, Dania; Gutierrez, Humerto; Sakti, Apurba; Adu, Kofi; Schimmel, Michael

    2010-03-31

    Hydrogen storage materials based on the hydrogen spillover mechanism onto metal-doped nanoporous carbons are studied, in an effort to develop materials that store appreciable hydrogen at ambient temperatures and moderate pressures. We demonstrate that oxidation of the carbon surface can significantly increase the hydrogen uptake of these materials, primarily at low pressure. Trace water present in the system plays a role in the development of active sites, and may further be used as a strategy to increase uptake. Increased surface density of oxygen groups led to a significant enhancement of hydrogen spillover at pressures less than 100 milibar. At 300K, the hydrogen uptake was up to 1.1 wt. % at 100 mbar and increased to 1.4 wt. % at 20 bar. However, only 0.4 wt% of this was desorbable via a pressure reduction at room temperature, and the high lowpressure hydrogen uptake was found only when trace water was present during pretreatment. Although far from DOE hydrogen storage targets, storage at ambient temperature has significant practical advantages oner cryogenic physical adsorbents. The role of trace water in surface modification has significant implications for reproducibility in the field. High-pressure in situ characterization of ideal carbon surfaces in hydrogen suggests re-hybridization is not likely under conditions of practical interest. Advanced characterization is used to probe carbon-hydrogen-metal interactions in a number of systems and new carbon materials have been developed.

  1. [Carbon capture and storage (CCS) and its potential role to mitigate carbon emission in China].

    PubMed

    Chen, Wen-Ying; Wu, Zong-Xin; Wang, Wei-Zhong

    2007-06-01

    Carbon capture and storage (CCS) has been widely recognized as one of the options to mitigate carbon emission to eventually stabilize carbon dioxide concentration in the atmosphere. Three parts of CCS, which are carbon capture, transport, and storage are assessed in this paper, covering comparisons of techno-economic parameters for different carbon capture technologies, comparisons of storage mechanism, capacity and cost for various storage formations, and etc. In addition, the role of CCS to mitigate global carbon emission is introduced. Finally, China MARKAL model is updated to include various CCS technologies, especially indirect coal liquefaction and poly-generation technologies with CCS, in order to consider carbon emission reduction as well as energy security issue. The model is used to generate different scenarios to study potential role of CCS to mitigate carbon emissions by 2050 in China. It is concluded that application of CCS can decrease marginal abatement cost and the decrease rate can reach 45% for the emission reduction rate of 50%, and it can lessen the dependence on nuclear power development for stringent carbon constrains. Moreover, coal resources can be cleanly used for longer time with CCS, e.g., for the scenario C70, coal share in the primary energy consumption by 2050 will increase from 10% when without CCS to 30% when with CCS. Therefore, China should pay attention to CCS R&D activities and to developing demonstration projects. PMID:17674718

  2. Effect of acid rain on calcium carbonate saturation in the Albemarle sound of North Carolina

    SciTech Connect

    Rudolph, K.A.; Burgess, S.K.; Willey, J.D.; Kieber, R.J.

    1996-10-01

    The effects of acidic rainwater additions on calcium carbonate solubility and alkalinity in the poorly buffered, biologically active and commercially important waters of the Albemarle Sound, NC are reported. Samples collected monthly at four sites were analyzed for salinity, pK total alkalinity, and calcium concentrations. Five percent and 10% dilutions of sulfuric acid at pH 4, mimicking acid rain additions, were added and total alkalinity and calcium concentrations again determined. The addition of acid decreased the alkalinity in the Albemarle samples by as much as 15%, although the magnitude of the impact depended both on site and season. The effects of acid additions on dissolved calcium concentrations were more variable,. and also displayed a site and season dependency. Calcium concentrations, alkalinity, and pH values were also determined during controlled laboratory experiments, where 25 mg/L Callinectes sapidus shells were added to Albemarle Sound water. All three analytes increased significantly upon acid additions relative to controls.

  3. Ubiquitylation functions in the calcium carbonate biomineralization in the extracellular matrix.

    PubMed

    Fang, Dong; Pan, Cong; Lin, Huijuan; Lin, Ya; Xu, Guangrui; Zhang, Guiyou; Wang, Hongzhong; Xie, Liping; Zhang, Rongqing

    2012-01-01

    Mollusks shell formation is mediated by matrix proteins and many of these proteins have been identified and characterized. However, the mechanisms of protein control remain unknown. Here, we report the ubiquitylation of matrix proteins in the prismatic layer of the pearl oyster, Pinctada fucata. The presence of ubiquitylated proteins in the prismatic layer of the shell was detected with a combination of western blot and immunogold assays. The coupled ubiquitins were separated and identified by Edman degradation and liquid chromatography/mass spectrometry (LC/MS). Antibody injection in vivo resulted in large amounts of calcium carbonate randomly accumulating on the surface of the nacreous layer. These ubiquitylated proteins could bind to specific faces of calcite and aragonite, which are the two main mineral components of the shell. In the in vitro calcium carbonate crystallization assay, they could reduce the rate of calcium carbonate precipitation and induce the calcite formation. Furthermore, when the attached ubiquitins were removed, the functions of the EDTA-soluble matrix of the prismatic layer were changed. Their potency to inhibit precipitation of calcium carbonate was decreased and their influence on the morphology of calcium carbonate crystals was changed. Taken together, ubiquitylation is involved in shell formation. Although the ubiquitylation is supposed to be involved in every aspect of biophysical processes, our work connected the biomineralization-related proteins and the ubiquitylation mechanism in the extracellular matrix for the first time. This would promote our understanding of the shell biomineralization and the ubiquitylation processes.

  4. A facile magnesium-containing calcium carbonate biomaterial as potential bone graft.

    PubMed

    He, Fupo; Zhang, Jing; Tian, Xiumei; Wu, Shanghua; Chen, Xiaoming

    2015-12-01

    The calcium carbonate is the main composition of coral which has been widely used as bone graft in clinic. Herein, we readily prepared novel magnesium-containing calcium carbonate biomaterials (MCCs) under the low-temperature conditions based on the dissolution-recrystallization reaction between unstable amorphous calcium carbonate (ACC) and metastable vaterite-type calcium carbonate with water involved. The content of magnesium in MCCs was tailored by adjusting the proportion of ACC starting material that was prepared using magnesium as stabilizer. The phase composition of MCCs with various amounts of magnesium was composed of one, two or three kinds of calcium carbonates (calcite, aragonite, and/or magnesian calcite). The different MCCs differed in topography. The in vitro degradation of MCCs accelerated with increasing amount of introduced magnesium. The MCCs with a certain amount of magnesium not only acquired higher compressive strength, but also promoted in vitro cell proliferation and osteogenic differentiation. Taken together, the facile MCCs shed light on their potential as bone graft.

  5. Control of calcium carbonate polymorphism and morphology through biomimetic mineralization by means of nanotechnology.

    PubMed

    Ichikawa, Kazuhiko; Shimomura, Noriyuki; Yamada, Masanori; Ohkubo, Naoki

    2003-07-21

    In vitro biomimetic mineralization by means of nanotechnology allows the formation of calcium carbonate polymorphs at low temperatures (<25 degrees C) under a CO(2) atmosphere of 500-1500 ppm. A two-dimensional zinc-ion ordered array (zinc array), which acts as an active-site mimic of carbonic anhydrase, has been prepared by immersing the self-organized monolayer of 3-(2-imidazolin-1-y)propyltriethosilane on mica (ImSi substrate) into aqueous zinc solution. The zinc array mounted on the ImSi substrate catalyzed the conversion from CO(2) to HCO(3) (-), and accelerated the formation of calcium carbonate. In situ X-ray diffraction data of the formed calcium carbonate on the poly(L-aspartate)-coated chitin substrate (pAsp substrate), with calcium ion-recognition sites, demonstrated that the interaction between the zinc array and pAsp substrates formed both vaterite and calcite at low temperature (15 degrees C) and mainly vaterite at 25 degrees C; this interaction also controlled the morphology of calcium carbonate formed on pAsp substrate.

  6. A facile magnesium-containing calcium carbonate biomaterial as potential bone graft.

    PubMed

    He, Fupo; Zhang, Jing; Tian, Xiumei; Wu, Shanghua; Chen, Xiaoming

    2015-12-01

    The calcium carbonate is the main composition of coral which has been widely used as bone graft in clinic. Herein, we readily prepared novel magnesium-containing calcium carbonate biomaterials (MCCs) under the low-temperature conditions based on the dissolution-recrystallization reaction between unstable amorphous calcium carbonate (ACC) and metastable vaterite-type calcium carbonate with water involved. The content of magnesium in MCCs was tailored by adjusting the proportion of ACC starting material that was prepared using magnesium as stabilizer. The phase composition of MCCs with various amounts of magnesium was composed of one, two or three kinds of calcium carbonates (calcite, aragonite, and/or magnesian calcite). The different MCCs differed in topography. The in vitro degradation of MCCs accelerated with increasing amount of introduced magnesium. The MCCs with a certain amount of magnesium not only acquired higher compressive strength, but also promoted in vitro cell proliferation and osteogenic differentiation. Taken together, the facile MCCs shed light on their potential as bone graft. PMID:26539810

  7. pH-dependent release property of alginate beads containing calcium carbonate particles.

    PubMed

    Han, M R; Kwon, M C; Lee, H Y; Kim, J C; Kim, J D; Yoo, S K; Sin, I S; Kim, S M

    2007-12-01

    Alginate bead containing calcium carbonate particle were prepared by dropping the suspension of alginate/calcium carbonate (4/1, w/w) into aqueous solution of CaCl(2) (0.1 M). The pH-dependent release property of the bead was observed for 12 h using blue dextran as a model drug. The release increased up to 4 h in a saturation manner. When no calcium carbonate was contained, the release exhibited no marked variation with pH and the values were 27-39%. On the other hand, in case calcium carbonate was included in the matrix of alginate beads, intensive release(40-50%) was achieved in acidic and neutral conditions and the degrees of release were suppressed in alkali conditions and the values were approximately 20%. The pH-sensitive release property is possibly because the particles of calcium carbonate embedded in the matrix of beads were leached out in acidic and neutral conditions, leaving cavities in the matrix. The cavities are likely to be main pathways for the release of blue dextran.

  8. Valuing the European 'coastal blue carbon' storage benefit.

    PubMed

    Luisetti, T; Jackson, E L; Turner, R K

    2013-06-15

    'Blue' carbon ecosystems are important carbon storage providers that are currently not protected by any international mechanism, such as REDD. This study aims to contribute to raising awareness in the political domain about the 'blue' carbon issue. This analysis also provides guidance in terms of how to value stock and flows of ecosystem services adding to the debate begun by the Costanza et al. (1997) paper in Nature. Through scenario analysis we assess how human welfare benefits will be affected by changes in the European coastal blue carbon stock provision. The current extent of European coastal blue carbon has an accounting stock value of about US$180 million. If EU Environmental Protection Directives continue to be implemented and effectively enforced, society will gain an appreciating asset over time. However, a future policy reversal resulting in extensive ecosystem loss could mean economic value losses as high as US$1 billion by 2060. PMID:23623654

  9. Valuing the European 'coastal blue carbon' storage benefit.

    PubMed

    Luisetti, T; Jackson, E L; Turner, R K

    2013-06-15

    'Blue' carbon ecosystems are important carbon storage providers that are currently not protected by any international mechanism, such as REDD. This study aims to contribute to raising awareness in the political domain about the 'blue' carbon issue. This analysis also provides guidance in terms of how to value stock and flows of ecosystem services adding to the debate begun by the Costanza et al. (1997) paper in Nature. Through scenario analysis we assess how human welfare benefits will be affected by changes in the European coastal blue carbon stock provision. The current extent of European coastal blue carbon has an accounting stock value of about US$180 million. If EU Environmental Protection Directives continue to be implemented and effectively enforced, society will gain an appreciating asset over time. However, a future policy reversal resulting in extensive ecosystem loss could mean economic value losses as high as US$1 billion by 2060.

  10. Forest management techniques for carbon dioxide storage

    SciTech Connect

    Fujimori, Takao

    1993-12-31

    In the global ecosystem concerning carbon dioxide content in the atmosphere, the forest ecosystem plays an important role. In effect, the ratio of forest biomass to total terrestrial biomass is about 90%, and the ratio of carbon stored in the forest biomass to that in the atmosphere is two thirds. When soils and detritus of forests are added, there is more C stored in forests than in the atmosphere, about 1.3 times or more. Thus, forests can be regarded as the great holder of C on earth. If the area of forest land on the earth is constantly maintained and forests are in the climax stage, the uptake of C and the release of C by and from the forests will balance. In this case, forests are neither sinks nor sources of CO{sub 2} although they store a large amount of C. However, when forests are deforested, they become a source of C; through human activities, forests have become a source of C. According to a report by the IPCC, 1.6{+-}1.2 PgC is annually added to the atmosphere by deforestation. According to the FAO (1992), the area of land deforested annually in the tropics from 1981 to 1990 was 16.9 x 10{sup 6} ha. This value is nearly half the area of Japanese land. The most important thing for the CO{sub 2} environment concerning forests is therefore how to reduce deforestation and to successfully implement a forestation or reforestation.

  11. Calcium.

    PubMed

    Williams, Robert J P

    2002-01-01

    This chapter describes the chemical and biological value of the calcium ion. In calcium chemistry, our main interest is in equilibria within static, nonflowing systems. Hence, we examined the way calcium formed precipitates and complex ions in solution. We observed thereafter its uses by humankind in a vast number of materials such as minerals, e.g., marble, concrete, mortars, which parallel the biological use in shells and bones. In complex formation, we noted that many combinations were of anion interaction with calcium for example in the uses of detergents and medicines. The rates of exchange of calcium from bound states were noted but they had little application. Calcium ions do not act as catalysts of organic reactions. In biological systems, interest is in the above chemistry, but extends to the fact that Ca2+ ions can carry information by flowing in one solution or from one solution to another through membranes. Hence, we became interested in the details of rates of calcium exchange. The fast exchange of this divalent ion from most organic binding sites has allowed it to develop as the dominant second messenger. Now the flow can be examined in vitro as calcium binds particular isolated proteins, which it activates as seen in physical mechanical changes or chemical changes and this piece-by-piece study of cells is common. Here, however, we have chosen to stress the whole circuit of Ca2+ action indicating that the cell is organized both at a basal and an activated state kinetic level by the steady state flow of the ion (see Fig. 11). Different time constants of exchange utilizing very similar binding constants lead to: 1) fast responses as in the muscle of an animal; or 2) slower change as in differentiation of an egg or seed. Many other changes of state may relate to Ca2+ steady-state levels of flow in the circuitry and here we point to two: 1) dormancy in reptiles and animals; and 2) sporulation in both bacteria and lower plants. In the other chapters of

  12. Elucidating the Effect of Biomolecule Structure on Calcium Carbonate Crystal Formation

    NASA Astrophysics Data System (ADS)

    Kulbok, K. E.; Duckworth, O.

    2011-12-01

    Anthropogenic emissions of carbon dioxide have lead to a steady increase in atmospheric concentration. This greenhouse gas has been identified as a key driver of climate change and also has lead to increased acidification of marine and terrestrial waters. Calcium carbonate precipitation at the Earth's surface is an integral linkage in the global carbon cycle, especially in regards to regulating atmospheric carbon dioxide. As concern for the effect of increasing atmospheric CO2 levels grows, the need to understand calcium carbonate systems escalates concurrently. Calcium carbonate phases are the most abundant group of biominerals; therefore, elucidating the mechanism of biomineralization is critical to understanding CaCO3 precipitation and may aid in the development of novel carbon sequestration strategies. The ubiquity of microorganisms leads to an extensive number of biomolecules present in the Earth's systems, and thus an extensive range of possible effects on CaCO3 formation. Carboxylic acids are very common biomolecules and have a relatively simple structure, thus making them an ideal family of model compounds. This study examines the kinetics, thermodynamics, phase, and morphology of calcium carbonate crystals precipitated in the presence of carboxylate-containing biomolecules, including citric acid, succinic acid, and aspartic acid. The experiments utilize a unique (NH4)2CO3 gas-diffusion reactor, which allows in-situ measurements of chemical conditions during the precipitation and growth of crystals. Continuous monitoring of the in-situ conditions of pCO2, pH, [Ca2+], and optical absorbance provides data on the supersaturation at which nucleation occurs and the kinetics of mineral growth. The use of scanning electron microscopy and X-ray diffraction provides information on the morphology and mineralogy of precipitates. The combination of these data sets will provide an in-depth view of the ideal concentration of calcium ions required for solution saturation

  13. Efficient phosphate binding using a combination of gluconolactate and carbonate calcium salts.

    PubMed

    Legendre, J Y; Cote, S; Pradeau, D; Hamon, M; Vitzling, C; Lavene, D; Tarral, A

    1994-08-01

    Although renal-failure-related hyperphosphataemia can be corrected by various phosphate binders, there remains a need for safer and more efficient formulations to precipitate phosphate. This work describes both a theoretical approach and a phosphate precipitation test in order to design efficient binding calcium salts formulations. The results show that the combination of a soluble calcium salt (the gluconolactate) and a proton-consuming calcium salt (the carbonate) can precipitate phosphate effectively. Furthermore, the theoretical computations correlate well with the ability of the salt to bind phosphate in vitro. PMID:7989401

  14. Calcium Carbonate Formation by Synechococcus sp. Strain PCC 8806 and Synechococcus sp. Strain PCC 8807

    SciTech Connect

    Lee, Brady D.; William A. Apel; Michelle R. Walton

    2006-12-01

    Precipitation of CaCO3 catalyzed by the growth and physiology of cyanobacteria in the Genus Synechococcus represents a potential mechanism for sequestration of CO2 produced during the burning of coal for power generation. Microcosm experiments were performed in which Synechococcus sp. strain PCC 8806 and Synechococcus sp. strain PCC 8807 were tested for their ability to calcify when exposed to a fixed calcium concentration of 3.4 mM and bicarbonate concentrations of 0.5, 1.25 and 2.5 mM. Disappearance of soluble calcium was used as an indicator of CaCO3 formation; results from metabolically active microcosms were compared to controls with no cells or no carbonate added. Synechococcus sp. strain PCC 8806 removed calcium continuously over the duration of the experiment with approximately 18.6 mg of calcium in the solid phase. Calcium removal occurred over a two-day time period when Synechococcus sp. strain PCC 8807 was tested and only 8.9 mg of calcium was removed in the solid phase. The ability of the cyanobacteria to create an alkaline growth environment appeared to be the primary factor responsible for CaCO3 precipitation in these experiments. Removal of inorganic carbon by fixation into biomass was insignificant compared to the mass of inorganic carbon removed by incorporation into the growing CaCO3 solid.

  15. An Integrated Approach to Predicting Carbon Dioxide Storage Capacity in Carbonate Reservoirs

    NASA Astrophysics Data System (ADS)

    Smith, M. M.; Hao, Y.; Mason, H. E.; Carroll, S.

    2015-12-01

    Carbonate reservoirs are widespread globally but pose unique challenges for geologic carbon dioxide (CO2) storage due to the reactive nature of carbonate minerals and the inherently heterogeneous pore structures of these rock types. Carbonate mineral dissolution resulting from CO2-acidified fluids may actually create new storage capacity, but predicting the extent and location of enhanced storage is complicated by the presence of pore size distributions spanning orders of magnitude as well as common microfractures. To address this issue, core samples spanning a wide range of depths and predicted permeabilities were procured from wells drilled into the Weyburn-Midale reservoir from the IEA GHG's CO2 Monitoring and Storage Project, Saskatchewan, Canada; and from the Arbuckle dolomite at the Kansas Geological Survey's South-central Kansas CO2 Project. Our approach integrated non-invasive characterization, complex core-flooding experiments, and 3-D reactive transport simulations to calibrate relevant CO2 storage relationships among fluid flow, porosity, permeability, and chemical reactivity. The resulting observations from this work permit us to constrain (and place uncertainty limits on) some of the model parameters needed for estimating evolving reservoir CO2 storage capacity. The challenge remains, however, as to how to best interpret and implement these observations at the actual reservoir scale. We present our key findings from these projects and recommendations for storage capacity predictions. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. Optimizing carbon storage and biodiversity protection in tropical agricultural landscapes.

    PubMed

    Gilroy, James J; Woodcock, Paul; Edwards, Felicity A; Wheeler, Charlotte; Medina Uribe, Claudia A; Haugaasen, Torbjørn; Edwards, David P

    2014-07-01

    With the rapidly expanding ecological footprint of agriculture, the design of farmed landscapes will play an increasingly important role for both carbon storage and biodiversity protection. Carbon and biodiversity can be enhanced by integrating natural habitats into agricultural lands, but a key question is whether benefits are maximized by including many small features throughout the landscape ('land-sharing' agriculture) or a few large contiguous blocks alongside intensive farmland ('land-sparing' agriculture). In this study, we are the first to integrate carbon storage alongside multi-taxa biodiversity assessments to compare land-sparing and land-sharing frameworks. We do so by sampling carbon stocks and biodiversity (birds and dung beetles) in landscapes containing agriculture and forest within the Colombian Chocó-Andes, a zone of high global conservation priority. We show that woodland fragments embedded within a matrix of cattle pasture hold less carbon per unit area than contiguous primary or advanced secondary forests (>15 years). Farmland sites also support less diverse bird and dung beetle communities than contiguous forests, even when farmland retains high levels of woodland habitat cover. Landscape simulations based on these data suggest that land-sparing strategies would be more beneficial for both carbon storage and biodiversity than land-sharing strategies across a range of production levels. Biodiversity benefits of land-sparing are predicted to be similar whether spared lands protect primary or advanced secondary forests, owing to the close similarity of bird and dung beetle communities between the two forest classes. Land-sparing schemes that encourage the protection and regeneration of natural forest blocks thus provide a synergy between carbon and biodiversity conservation, and represent a promising strategy for reducing the negative impacts of agriculture on tropical ecosystems. However, further studies examining a wider range of ecosystem

  17. Why to synthesize vaterite polymorph of calcium carbonate on the cellulose matrix via sonochemistry process?

    PubMed

    Fu, Lian-Hua; Dong, Yan-Yan; Ma, Ming-Guo; Yue, Wen; Sun, Shao-Long; Sun, Run-Cang

    2013-09-01

    Vaterite is an important biomedical material due to its features such as high specific surface area, high solubility, high dispersion, and small specific gravity. The purposes of this article were to explore the growth mechanism of vaterite on the cellulose matrix via sonochmistry process. In the work reported herein, the influences of experimental parameters on the polymorph of calcium carbonate were investigated in detail. The calcium carbonate crystals on the cellulose matrix were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Experimental results revealed that all the reactants, solvent, and synthesis method played an important role in the polymorph of calcium carbonate. The pure phase of vaterite polymorph was obtained using Na2CO3 as reactant in ethylene glycol on the cellulose matrix via sonochmistry process. Based on the experimental results, one can conclude that the synthesis of vaterite polymorph is a system process.

  18. Bio-deposition of a calcium carbonate layer on degraded limestone by Bacillus species.

    PubMed

    Dick, Jan; De Windt, Wim; De Graef, Bernard; Saveyn, Hans; Van der Meeren, Paul; De Belie, Nele; Verstraete, Willy

    2006-08-01

    To obtain a restoring and protective calcite layer on degraded limestone, five different strains of the Bacillus sphaericus group and one strain of Bacillus lentus were tested for their ureolytic driven calcium carbonate precipitation. Although all the Bacillus strains were capable of depositing calcium carbonate, differences occurred in the amount of precipitated calcium carbonate on agar plate colonies. Seven parameters involved in the process were examined: calcite deposition on limestone cubes, pH increase, urea degrading capacity, extracellular polymeric substances (EPS)-production, biofilm formation, zeta-potential and deposition of dense crystal layers. The strain selection for optimal deposition of a dense CaCO(3) layer on limestone, was based on decrease in water absorption rate by treated limestone. Not all of the bacterial strains were effective in the restoration of deteriorated Euville limestone. The best calcite precipitating strains were characterised by high ureolytic efficiency, homogeneous calcite deposition on limestone cubes and a very negative zeta-potential. PMID:16491305

  19. Synthesis of novel amorphous calcium carbonate by sono atomization for reactive mixing.

    PubMed

    Kojima, Yoshiyuki; Kanai, Makoto; Nishimiya, Nobuyuki

    2012-03-01

    Droplets of several micrometers in size can be formed in aqueous solution by atomization under ultrasonic irradiation at 2 MHz. This phenomenon, known as atomization, is capable of forming fine droplets for use as a reaction field. This synthetic method is called SARM (sono atomization for reactive mixing). This paper reports on the synthesis of a novel amorphous calcium carbonate formed by SARM. The amorphous calcium carbonate, obtained at a solution concentration of 0.8 mol/dm(3), had a specific surface area of 65 m(2)/g and a composition of CaCO(3)•0.5H(2)O as determined using thermogravimetric/differential thermal analysis (TG-DTA). Because the ACC had a lower hydrate composition than conventional amorphous calcium carbonate (ACC), the ACC synthesized in this paper was very stable at room temperature.

  20. Bio-deposition of a calcium carbonate layer on degraded limestone by Bacillus species.

    PubMed

    Dick, Jan; De Windt, Wim; De Graef, Bernard; Saveyn, Hans; Van der Meeren, Paul; De Belie, Nele; Verstraete, Willy

    2006-08-01

    To obtain a restoring and protective calcite layer on degraded limestone, five different strains of the Bacillus sphaericus group and one strain of Bacillus lentus were tested for their ureolytic driven calcium carbonate precipitation. Although all the Bacillus strains were capable of depositing calcium carbonate, differences occurred in the amount of precipitated calcium carbonate on agar plate colonies. Seven parameters involved in the process were examined: calcite deposition on limestone cubes, pH increase, urea degrading capacity, extracellular polymeric substances (EPS)-production, biofilm formation, zeta-potential and deposition of dense crystal layers. The strain selection for optimal deposition of a dense CaCO(3) layer on limestone, was based on decrease in water absorption rate by treated limestone. Not all of the bacterial strains were effective in the restoration of deteriorated Euville limestone. The best calcite precipitating strains were characterised by high ureolytic efficiency, homogeneous calcite deposition on limestone cubes and a very negative zeta-potential.

  1. Immobilization of Pseudomonas sp. DG17 onto sodium alginate–attapulgite–calcium carbonate

    PubMed Central

    Wang, Hong Qi; Hua, Fei; Zhao, Yi Cun; Li, Yi; Wang, Xuan

    2014-01-01

    A strain of Pseudomonas sp. DG17, capable of degrading crude oil, was immobilized in sodium alginate–attapulgite–calcium carbonate for biodegradation of crude oil contaminated soil. In this work, proportion of independent variables, the laboratory immobilization parameters, the micromorphology and internal structure of the immobilized granule, as well as the crude oil biodegradation by sodium alginate–attapulgite–calcium carbonate immobilized cells and sodium alginate–attapulgite immobilized cells were studied to build the optimal immobilization carrier and granule-forming method. The results showed that the optimal concentrations of sodium alginate–attapulgite–calcium carbonate and calcium chloride were 2.5%–3.5%, 0.5%–1%, 3%–7% and 2%–4%, respectively. Meanwhile, the optimal bath temperature, embedding cell amount, reaction time and multiplication time were 50–60 °C, 2%, 18 h and 48 h, respectively. Moreover, biodegradation was enhanced by immobilized cells with a total petroleum hydrocarbon removal ranging from 33.56% ± 3.84% to 56.82% ± 3.26% after 20 days. The SEM results indicated that adding calcium carbonate was helpful to form internal honeycomb-like pores in the immobilized granules. PMID:26019567

  2. The effect of bile on the crystallisation of calcium carbonate, a constituent of gallstones.

    PubMed

    Sutor, D J; Percival, J M

    1978-11-01

    When calcium and bicarbonate ions were mixed at room temperature (approximately 20 degrees C) to give concentrations of 4 mmol/1 and 21 mmol/1 respectively and the pH of the solution was kept at 8.3, vaterite, a form of calcium carbonate, was precipitated almost immediately as spheres of diameter 45 micron. The crystallisation of this material could be slowed down by adding to the crystallising medium small amounts of pyrophosphate or citrate which often inhibit crystal growth. High concentrations of sodium chloride (90 mmol/1) did not, however, affect the reaction. Very small amounts of gallbladder bile from patients with only cholesterol on the surface of their gallstones inhibited the crystallisation of calcium carbonate, and the size of the spheres was only 0.37 times those produced in water. The activity of the bile could be attributed to material with a molecular weight greater than 10 000. On the other hand, bile from patients having some calcium carbonate on the gallstone surface had less activity than comparable amounts of bile from patients with only cholesterol in this area. The active material may, therefore, play a part in preventing the deposition of calcium carbonate in gallstones. PMID:30554

  3. The influence of electron discharge and magnetic field on calcium carbonate (CaCO3) precipitation

    NASA Astrophysics Data System (ADS)

    Putro, Triswantoro; Endarko

    2016-04-01

    The influences of electron discharge and magnetic field on calcium carbonate (CaCO3) precipitation in water have been successfully investigated. The study used three pairs of magnetic field 0.1 T whilst the electron discharge was generated from television flyback transformer type BW00607 and stainless steel SUS 304 as an electrode. The water sample with an initial condition of 230 mg/L placed in the reactor with flow rate 375 mL/minutes, result showed that the electron discharge can be reduced contain of calcium carbonate the water sample around 17.39% within 2 hours. Meanwhile for the same long period of treatment and flow rate, around 56.69% from initial condition of 520 mg/L of calcium carbonate in the water sample can be achieved by three pairs of magnetic field 0.1 T. When the combination of three pairs of magnetic field 0.1 T and the electron discharge used for treatment, the result showed that the combination of electron discharge and magnetic field methods can be used to precipitate calcium carbonate in the water sample 300 mg/L around 76.66% for 2 hours of treatment. The study then investigated the influence of the polar position of the magnetic field on calcium carbonate precipitation. Two positions of magnetic field were tested namely the system with alternated polar magnetics and the system without inversion of the polar magnetics. The influence of the polar position showed that the percentage reduction in levels of calcium carbonate in the water sample (360 mg/L) is significant different. Result showed that the system without inversion of the polar magnetics is generally lower than the system with alternated polar magnetics, with reduction level at 30.55 and 57.69%, respectively.

  4. Effect of calcium carbonate on clinical compliance of apatitic calcium phosphate bone cement.

    PubMed

    Khairoun, I; Boltong, M G; Driessens, F C; Planell, J A

    1997-01-01

    Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time, and the ultimate compressive strength. Two cement formulations were tested. Biocement F was made of a powder containing alpha-tertiary calcium phosphate, precipitated hydroxyapatite, and monetite. Biocement D powder also contained CaCO3. The liquid/powder (L/P) ratio of the cement paste and the accelerator concentrations (% Na2HPO4) in the cement liquid were varied. For Biocement F there was a small area of combinations of L/P ratio and percent Na2HPO4 for which all clinical requirements were satisfied. This area covered only pastes that could be applied as doughs. However, Biocement D showed a much larger area of full compliance and it covered both doughlike and injectable pastes.

  5. The potential for carbon storage in UK peatlands

    NASA Astrophysics Data System (ADS)

    Rowson, J.; Worrall, F.; Evans, M.; Bonn, A.; Reed, M.; Chapman, D.; Holden, J.

    2008-12-01

    Upland peat soils represent a large terrestrial carbon store and as such have the potential to be either an ongoing net sink of carbon or a significant net source of carbon. In the UK many upland peats are managed for a range of purposes but these purposes have rarely included carbon stewardship. However, there is now an opportunity to consider whether management practices could be altered to enhance storage of carbon in upland peats. Further, there are now voluntary and regulated carbon trading schemes operational throughout Europe that mean stored carbon, if verified, could have an economic and tradeable value. This means that new income streams could become available for upland management. The 'Sustainable Uplands' RELU project has developed a model for calculating carbon fluxes from peat soils that covers all carbon uptake and release pathways (e.g. fluvial and gaseous pathways). The model has been developed so that the impact of common management options within UK upland peats can be considered. The model was run for a decade from 1997-2006 and applied to an area of 550 km2 of upland peat soils in the Peak District. The study estimates that the region is presently a net sink of -62 Ktonnes CO2 equivalent at an average export of - 136 tonnes CO2 equivalent/km2/yr. If management interventions were targeted across the area the total sink could increase to -160 Ktonnes CO2/yr at an average export of- 219 tonnes CO2 equivalent/km2/yr. The model suggests which management interventions would be most effective and given present costs of peatland restoration and value of carbon offsets the study suggests that 51% of those areas, where a carbon benefit was estimated by modelling for targeted action of management interventions, would show a profit from carbon offsetting within 30 years.

  6. Fracture Dissolution of Carbonate Rock: An Innovative Process for Gas Storage

    SciTech Connect

    James W. Castle; Ronald W. Falta; David Bruce; Larry Murdoch; Scott E. Brame; Donald Brooks

    2006-10-31

    The goal of the project is to develop and assess the feasibility and economic viability of an innovative concept that may lead to commercialization of new gas-storage capacity near major markets. The investigation involves a new approach to developing underground gas storage in carbonate rock, which is present near major markets in many areas of the United States. Because of the lack of conventional gas storage and the projected growth in demand for storage capacity, many of these areas are likely to experience shortfalls in gas deliverability. Since depleted gas reservoirs and salt formations are nearly non-existent in many areas, alternatives to conventional methods of gas storage are required. The need for improved methods of gas storage, particularly for ways to meet peak demand, is increasing. Gas-market conditions are driving the need for higher deliverability and more flexibility in injection/withdrawal cycling. In order to meet these needs, the project involves an innovative approach to developing underground storage capacity by creating caverns in carbonate rock formations by acid dissolution. The basic concept of the acid-dissolution method is to drill to depth, fracture the carbonate rock layer as needed, and then create a cavern using an aqueous acid to dissolve the carbonate rock. Assessing feasibility of the acid-dissolution method included a regional geologic investigation. Data were compiled and analyzed from carbonate formations in six states: Indiana, Ohio, Kentucky, West Virginia, Pennsylvania, and New York. To analyze the requirements for creating storage volume, the following aspects of the dissolution process were examined: weight and volume of rock to be dissolved; gas storage pressure, temperature, and volume at depth; rock solubility; and acid costs. Hydrochloric acid was determined to be the best acid to use because of low cost, high acid solubility, fast reaction rates with carbonate rock, and highly soluble products (calcium chloride

  7. Nanostructured carbon and carbon nanocomposites for electrochemical energy storage applications.

    PubMed

    Su, Dang Sheng; Schlögl, Robert

    2010-02-22

    Electrochemical energy storage is one of the important technologies for a sustainable future of our society, in times of energy crisis. Lithium-ion batteries and supercapacitors with their high energy or power densities, portability, and promising cycling life are the cores of future technologies. This Review describes some materials science aspects on nanocarbon-based materials for these applications. Nanostructuring (decreasing dimensions) and nanoarchitecturing (combining or assembling several nanometer-scale building blocks) are landmarks in the development of high-performance electrodes for with long cycle lifes and high safety. Numerous works reviewed herein have shown higher performances for such electrodes, but mostly give diverse values that show no converging tendency towards future development. The lack of knowledge about interface processes and defect dynamics of electrodes, as well as the missing cooperation between material scientists, electrochemists, and battery engineers, are reasons for the currently widespread trial-and-error strategy of experiments. A concerted action between all of these disciplines is a prerequisite for the future development of electrochemical energy storage devices.

  8. How does an amorphous surface influence molecular binding?--ovocleidin-17 and amorphous calcium carbonate.

    PubMed

    Freeman, Colin L; Harding, John H; Quigley, David; Rodger, P Mark

    2015-07-14

    Atomistic molecular dynamics simulations of dehydrated amorphous calcium carbonate interacting with the protein ovocleidin-17 are presented. These simulations demonstrate that the amorphisation of the calcium carbonate surface removes water structure from the surface. This reduction of structure allows the protein to bind with many residues, unlike on crystalline surfaces where binding is strongest when only a few residues are attached to the surface. Basic residues are observed to dominate the binding interactions. The implications for protein control over crystallisation are discussed. PMID:26009013

  9. The mechanical and NIR studies on ultrafine calcium carbonate treated by four surface modifiers.

    PubMed

    Shui, Miao; Yue, Linhai; Xu, Zhude

    2004-01-01

    Calcium carbonate was surface treated by acrylic acid monomer, its polymerization with varied mean molecular weight and PS/PAA copolymer. Coating efficiencies for these four series of surface-treated calcium carbonate were investigated. They differ from each other in many aspects. We hypothesize that the treating molecules bond to and align on the particle surface in different ways before and after monolayer coverage was reached. NIR spectra of surface-treated samples studied not only reflected the amount of bonded treating agents by means of the value of absorbance, but also gave rich structural information of surface layer. This gave us a powerful means to investigate the interface of particle surface.

  10. Synthesis, characterization and hydrogen storage studies on porous carbon

    SciTech Connect

    Ruz, Priyanka Banerjee, Seemita; Sudarsan, V.; Pandey, M.

    2015-06-24

    Porous carbon sample has been prepared, using zeolite-Y as template followed by annealing at 800°C, with view to estimate the extent of hydrogen storage by the sample. Based on XRD, {sup 13}C MAS NMR and Raman spectroscopic studies it is confirmed that the porous Carbon sample contains only sp{sup 2} hybridized carbon. The hydrogen sorption isotherms have been recorded for the sample at 273, 223K and 123K and the maximum hydrogen absorption capacity is found to be 1.47wt% at 123K. The interaction energy of hydrogen with the carbon framework was determined to be ∼ 10 kJ mol{sup −1}at lower hydrogen uptake and gradually decreases with increase in hydrogen loading.

  11. Thermal breakdown of calcium carbonate and constraints on its use as a biomarker

    NASA Astrophysics Data System (ADS)

    Thompson, Stephen P.; Parker, Julia E.; Tang, Chiu C.

    2014-02-01

    Observed differences in the thermal behaviour of calcium carbonates of biogenic and abiogenic origin (phase transformation and breakdown temperatures) are widely cited as potential biomarkers for whether life once existed on Mars. Although seemingly compelling, there has been no systematic investigation into the physical mechanism behind these apparent differences and therefore no direct proof that they are uniquely diagnostic of a biogenic versus abiogenic formation. In this paper we present a laboratory investigation into the thermal behaviour of two high purity calcium carbonates, one of which was produced in the presence of an amino acid as a biomimetic carbonate. In situ synchrotron X-ray powder diffraction measurements show the aragonite-to-calcite phase transition and calcite-to-oxide breakdown temperatures are significantly lower in the biomimetic carbonate. The observed thermal differences closely match reported differences between biogenic and geological abiogenic carbonates. The biomimetic carbonate exhibits a modified crystal morphology, with a highly strained internal crystal lattice, similar to biogenic carbonate structures. Since biogenic carbonates are formed in the presence of organic macromolecules such as amino acids, the induced microstrain appears to be the defining common factor as it adds an additional energy term to the carbonate lattice energy, which lowers the activation energy required for structural transformation or decomposition. Although produced via biomimetic means, the carbonate investigated here is nevertheless abiogenic in origin and we propose that given suitable localised conditions such as pooled water and a supply of organic molecules, naturally occurring biomimetic carbonates could have similarly formed on the martian surface and could therefore exhibit the same thermal characteristics as biogenic carbonate. Thus as a limiting case - without other supporting observations - the thermal behaviour of martian calcium carbonate

  12. The Potential of Microbial Activity to Increase the Efficacy of Geologic Carbon Capture and Storage

    NASA Astrophysics Data System (ADS)

    Cunningham, A. B.; Gerlach, R.; Phillips, A. J.; Eldring, J.; Lauchnor, E.; Klapper, I.; Ebigbo, A.; Mitchell, A. C.; Spangler, L.

    2012-12-01

    Geologic carbon capture and storage involves the injection of CO2 into underground formations such as brine aquifers where microbe-rock-fluid interactions will occur. These interactions may be important for the long-term fate of the injected CO2 particularly near well bores and potential leakage pathways. Herein, concepts and results are presented from bench to meso-scale experiments focusing on the utility of attached microorganisms and biofilms to enhance storage security of injected CO2. Batch and flow experiments at atmospheric and geologic CO2storage-relevant pressures have demonstrated the ability of microbial biofilms to decrease the permeability of natural and artificial porous media, survive the exposure to scCO2, and facilitate the conversion of CO2 into long-term stable carbonate phases as well as increase the solubility of CO2 in brines. Recently, the microbially catalyzed process of ureolysis has been investigated for the potential to promote calcium carbonate mineralization in subsurface reservoirs using native or introduced ureolytic microorganisms, which increase the saturation state of CaCO3 via the hydrolysis of urea. The anticipated applications for this biomineralization process in the subsurface include sealing microfractures and CO2 leakage pathways for increased security of geologic carbon storage. Recent work has focused on facilitating this biomineralization process in large scale (74 cm diameter, 38 cm high sandstone) radial flow systems under ambient and subsurface relevant pressures with the goal of developing injection strategies suited for field scale deployment. Methods for microscopic and macroscopic visualization of relevant processes, such as growth of microbial biofilms, their interactions with minerals and influence on pore spaces in porous media reactors are being developed and have been used to calibrate reactive transport models. As a result, these models are being used to predict the effect of biological processes on CO2

  13. Effects of Sigma Anti-bonding Molecule Calcium Carbonate on bone turnover and calcium balance in ovariectomized rats.

    PubMed

    Choi, So-Young; Park, Dongsun; Yang, Goeun; Lee, Sun Hee; Bae, Dae Kwon; Hwang, Seock-Yeon; Lee, Paul K; Kim, Yun-Bae; Kim, Ill-Hwa; Kang, Hyun-Gu

    2011-12-01

    This study was conducted to evaluate the effect of Sigma Anti-bonding Molecule Calcium Carbonate (SAC) as therapy for ovariectomy-induced osteoporosis in rats. Three weeks after surgery, fifteen ovariectomized Sprague-Dawley rats were divided randomly into 3 groups: sham-operated group (sham), ovariectomized group (OVX) and SAC-treatment group (OVX+SAC). The OVX+SAC group was given drinking water containing 0.0012% SAC for 12 weeks. Bone breaking force and mineralization as well as blood parameters related to the bone metabolism were analyzed. In OVX animals, blood concentration of 17β-estradiol decreased significantly, while osteocalcin and type I collagen C-terminal telopeptides (CTx) increased. Breaking force, bone mineral density (BMD), calcium and phosphorus in femurs, as well as uterine and vaginal weights, decreased significantly following OVX. However, SAC treatment (0.0012% in drinking water) not only remarkably restored the decreased 17β-estradiol and increased osteocalcin and CTx concentrations, but also recovered decreased femoral breaking force, BMD, calcium and phosphorus, although it did not reversed reproductive organ weights. It is suggested that SAC effectively improve bone density by preventing bone turnover mediated osteocalcin, CTx and minerals, and that it could be a potential candidate for therapy or prevention of postmenopausal osteoporosis.

  14. The Influence of Calcium Carbonate Grain Coatings on Contaminant Reactivity in Vadose Zone Sediments

    SciTech Connect

    Zachara, John M.; Chambers, Scott; Brown Jr., Gordon E.; Eggleston, Carrick M.

    2001-06-01

    Calcium carbonate (CaCO3) is widely distributed through the Hanford vadose zone as a minor phase. As a result of current and past geochemical processes, CaCO3 exists as grain coatings, intergrain fill, and distinct caliche layers in select locations. Calcium carbonate may also precipitate when high-level wastes react with naturally Ca- and Mg-saturated Hanford sediments. Calcium carbonate is a very reactive mineral phase. Sorption reactions on its surface may slow the migration of certain contaminants (Co, Sr), but its surface coatings on other mineral phases may diminish contaminant retardation (for example, Cr) by blocking surface reaction sites of the substrate. This project explores the behavior of calcium carbonate grain coatings, including how they form and dissolve, their reactivity toward key Hanford contaminants, their impact (as surface coatings) on the reactivity of other mineral substrates, and on their in-ground composition and minor element enrichment. The importance of CaCO3 as a contaminant sorbent will be defined in all of its different manifestations in Hanford sediments: dispersed minor lithic fragments, pedogenic carbonate coatings on gravel and stringers in silt, and nodules in clay and paleosols. Mass action models will be developed that allow understanding and prediction of the geochemical effects of CaCO3 on contaminant retardation in Hanford sediments.

  15. Enzyme-accelerated and structure-guided crystallization of calcium carbonate: role of the carbonic anhydrase in the homologous system.

    PubMed

    Müller, Werner E G; Schlossmacher, Ute; Schröder, Heinz C; Lieberwirth, Ingo; Glasser, Gunnar; Korzhev, Michael; Neufurth, Meik; Wang, Xiaohong

    2014-01-01

    The calcareous spicules from sponges, e.g. from Sycon raphanus, are composed of almost pure calcium carbonate. In order to elucidate the formation of those structural skeletal elements, the function of the enzyme carbonic anhydrase (CA), isolated from this species, during the in vitro calcium carbonate-based spicule formation, was investigated. It is shown that the recombinant sponge CA substantially accelerates calcium carbonate formation in the in vitro diffusion assay. A stoichiometric calculation revealed that the turnover rate of the sponge CA during the calcification process amounts to 25 CO2s(-1) × molecule CA(-1). During this enzymatically driven process, initially pat-like particles are formed that are subsequently transformed to rhomboid/rhombohedroid crystals with a dimension of ~50 μm. The CA-catalyzed particles are smaller than those which are formed in the absence of the enzyme. The Martens hardness of the particles formed is ~4 GPa, a value which had been determined for other biogenic calcites. This conclusion is corroborated by energy-dispersive X-ray spectroscopy, which revealed that the particles synthesized are composed predominantly of the elements calcium, oxygen and carbon. Surprising was the finding, obtained by light and scanning electron microscopy, that the newly formed calcitic crystals associate with the calcareous spicules from S. raphanus in a highly ordered manner; the calcitic crystals almost perfectly arrange in an array orientation along the two opposing planes of the spicules, leaving the other two plane arrays uncovered. It is concluded that the CA is a key enzyme controlling the calcium carbonate biomineralization process, which directs the newly formed particles to existing calcareous spicular structures. It is expected that with the given tools new bioinspired materials can be fabricated.

  16. Degraded tropical rain forests possess valuable carbon storage opportunities in a complex, forested landscape.

    PubMed

    Alamgir, Mohammed; Campbell, Mason J; Turton, Stephen M; Pert, Petina L; Edwards, Will; Laurance, William F

    2016-07-20

    Tropical forests are major contributors to the terrestrial global carbon pool, but this pool is being reduced via deforestation and forest degradation. Relatively few studies have assessed carbon storage in degraded tropical forests. We sampled 37,000 m(2) of intact rainforest, degraded rainforest and sclerophyll forest across the greater Wet Tropics bioregion of northeast Australia. We compared aboveground biomass and carbon storage of the three forest types, and the effects of forest structural attributes and environmental factors that influence carbon storage. Some degraded forests were found to store much less aboveground carbon than intact rainforests, whereas others sites had similar carbon storage to primary forest. Sclerophyll forests had lower carbon storage, comparable to the most heavily degraded rainforests. Our findings indicate that under certain situations, degraded forest may store as much carbon as intact rainforests. Strategic rehabilitation of degraded forests could enhance regional carbon storage and have positive benefits for tropical biodiversity.

  17. Degraded tropical rain forests possess valuable carbon storage opportunities in a complex, forested landscape.

    PubMed

    Alamgir, Mohammed; Campbell, Mason J; Turton, Stephen M; Pert, Petina L; Edwards, Will; Laurance, William F

    2016-01-01

    Tropical forests are major contributors to the terrestrial global carbon pool, but this pool is being reduced via deforestation and forest degradation. Relatively few studies have assessed carbon storage in degraded tropical forests. We sampled 37,000 m(2) of intact rainforest, degraded rainforest and sclerophyll forest across the greater Wet Tropics bioregion of northeast Australia. We compared aboveground biomass and carbon storage of the three forest types, and the effects of forest structural attributes and environmental factors that influence carbon storage. Some degraded forests were found to store much less aboveground carbon than intact rainforests, whereas others sites had similar carbon storage to primary forest. Sclerophyll forests had lower carbon storage, comparable to the most heavily degraded rainforests. Our findings indicate that under certain situations, degraded forest may store as much carbon as intact rainforests. Strategic rehabilitation of degraded forests could enhance regional carbon storage and have positive benefits for tropical biodiversity. PMID:27435389

  18. Degraded tropical rain forests possess valuable carbon storage opportunities in a complex, forested landscape

    NASA Astrophysics Data System (ADS)

    Alamgir, Mohammed; Campbell, Mason J.; Turton, Stephen M.; Pert, Petina L.; Edwards, Will; Laurance, William F.

    2016-07-01

    Tropical forests are major contributors to the terrestrial global carbon pool, but this pool is being reduced via deforestation and forest degradation. Relatively few studies have assessed carbon storage in degraded tropical forests. We sampled 37,000 m2 of intact rainforest, degraded rainforest and sclerophyll forest across the greater Wet Tropics bioregion of northeast Australia. We compared aboveground biomass and carbon storage of the three forest types, and the effects of forest structural attributes and environmental factors that influence carbon storage. Some degraded forests were found to store much less aboveground carbon than intact rainforests, whereas others sites had similar carbon storage to primary forest. Sclerophyll forests had lower carbon storage, comparable to the most heavily degraded rainforests. Our findings indicate that under certain situations, degraded forest may store as much carbon as intact rainforests. Strategic rehabilitation of degraded forests could enhance regional carbon storage and have positive benefits for tropical biodiversity.

  19. Degraded tropical rain forests possess valuable carbon storage opportunities in a complex, forested landscape

    PubMed Central

    Alamgir, Mohammed; Campbell, Mason J.; Turton, Stephen M.; Pert, Petina L.; Edwards, Will; Laurance, William F.

    2016-01-01

    Tropical forests are major contributors to the terrestrial global carbon pool, but this pool is being reduced via deforestation and forest degradation. Relatively few studies have assessed carbon storage in degraded tropical forests. We sampled 37,000 m2 of intact rainforest, degraded rainforest and sclerophyll forest across the greater Wet Tropics bioregion of northeast Australia. We compared aboveground biomass and carbon storage of the three forest types, and the effects of forest structural attributes and environmental factors that influence carbon storage. Some degraded forests were found to store much less aboveground carbon than intact rainforests, whereas others sites had similar carbon storage to primary forest. Sclerophyll forests had lower carbon storage, comparable to the most heavily degraded rainforests. Our findings indicate that under certain situations, degraded forest may store as much carbon as intact rainforests. Strategic rehabilitation of degraded forests could enhance regional carbon storage and have positive benefits for tropical biodiversity. PMID:27435389

  20. [Effects of climate change on forest soil organic carbon storage: a review].

    PubMed

    Zhou, Xiao-yu; Zhang, Cheng-yi; Guo, Guang-fen

    2010-07-01

    Forest soil organic carbon is an important component of global carbon cycle, and the changes of its accumulation and decomposition directly affect terrestrial ecosystem carbon storage and global carbon balance. Climate change would affect the photosynthesis of forest vegetation and the decomposition and transformation of forest soil organic carbon, and further, affect the storage and dynamics of organic carbon in forest soils. Temperature, precipitation, atmospheric CO2 concentration, and other climatic factors all have important influences on the forest soil organic carbon storage. Understanding the effects of climate change on this storage is helpful to the scientific management of forest carbon sink, and to the feasible options for climate change mitigation. This paper summarized the research progress about the distribution of organic carbon storage in forest soils, and the effects of elevated temperature, precipitation change, and elevated atmospheric CO2 concentration on this storage, with the further research subjects discussed.

  1. Interplay between microorganisms and geochemistry in geological carbon storage

    DOE PAGES

    Altman, Susan J.; Kirk, Matthew Fletcher; Santillan, Eugenio-Felipe U.; Bennett, Philip C.

    2016-02-28

    Researchers at the Center for Frontiers of Subsurface Energy Security (CFSES) have conducted laboratory and modeling studies to better understand the interplay between microorganisms and geochemistry for geological carbon storage (GCS). We provide evidence of microorganisms adapting to high pressure CO2 conditions and identify factors that may influence survival of cells to CO2 stress. Factors that influenced the ability of cells to survive exposure to high-pressure CO2 in our experiments include mineralogy, the permeability of cell walls and/or membranes, intracellular buffering capacity, and whether cells live planktonically or within biofilm. Column experiments show that, following exposure to acidic water, biomassmore » can remain intact in porous media and continue to alter hydraulic conductivity. Our research also shows that geochemical changes triggered by CO2 injection can alter energy available to populations of subsurface anaerobes and that microbial feedbacks on this effect can influence carbon storage. Our research documents the impact of CO2 on microorganisms and in turn, how subsurface microorganisms can influence GCS. Furthermore, we conclude that microbial presence and activities can have important implications for carbon storage and that microorganisms should not be overlooked in further GCS research.« less

  2. CO.sub.2 Pretreatment prevents calcium carbonate formation

    DOEpatents

    Neavel, Richard C.; Brunson, Roy J.; Chaback, Joseph J.

    1980-01-01

    Scale formation during the liquefaction of lower ranking coals and similar carbonaceous materials is significantly reduced and/or prevented by pretreatment with carbon dioxide. The carbon dioxide pretreatment is believed to convert the scale-forming components to the corresponding carbonate prior to liquefaction. The pretreatment is accomplished at a total pressure within the range from about 14 to about 68 atmospheres and a carbon dioxide partial pressure within the range from about 14 to about 34 atmospheres. Temperature during pretreatment will generally be within the range from about 100.degree. to about 200.degree. C.

  3. Chemical analysis and molecular models for calcium-oxygen-carbon interactions in black carbon found in fertile Amazonian anthrosoils.

    PubMed

    Archanjo, Braulio S; Araujo, Joyce R; Silva, Alexander M; Capaz, Rodrigo B; Falcão, Newton P S; Jorio, Ado; Achete, Carlos A

    2014-07-01

    Carbon particles containing mineral matter promote soil fertility, helping it to overcome the rather unfavorable climate conditions of the humid tropics. Intriguing examples are the Amazonian Dark Earths, anthropogenic soils also known as "Terra Preta de Índio'' (TPI), in which chemical recalcitrance and stable carbon with millenary mean residence times have been observed. Recently, the presence of calcium and oxygen within TPI-carbon nanoparticles at the nano- and mesoscale ranges has been demonstrated. In this work, we combine density functional theory calculations, scanning transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transformed infrared spectroscopy, and high resolution X-ray photoelectron spectroscopy of TPI-carbons to elucidate the chemical arrangements of calcium-oxygen-carbon groups at the molecular level in TPI. The molecular models are based on graphene oxide nanostructures in which calcium cations are strongly adsorbed at the oxide sites. The application of material science techniques to the field of soil science facilitates a new level of understanding, providing insights into the structure and functionality of recalcitrant carbon in soil and its implications for food production and climate change. PMID:24892495

  4. Chemical analysis and molecular models for calcium-oxygen-carbon interactions in black carbon found in fertile Amazonian anthrosoils.

    PubMed

    Archanjo, Braulio S; Araujo, Joyce R; Silva, Alexander M; Capaz, Rodrigo B; Falcão, Newton P S; Jorio, Ado; Achete, Carlos A

    2014-07-01

    Carbon particles containing mineral matter promote soil fertility, helping it to overcome the rather unfavorable climate conditions of the humid tropics. Intriguing examples are the Amazonian Dark Earths, anthropogenic soils also known as "Terra Preta de Índio'' (TPI), in which chemical recalcitrance and stable carbon with millenary mean residence times have been observed. Recently, the presence of calcium and oxygen within TPI-carbon nanoparticles at the nano- and mesoscale ranges has been demonstrated. In this work, we combine density functional theory calculations, scanning transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transformed infrared spectroscopy, and high resolution X-ray photoelectron spectroscopy of TPI-carbons to elucidate the chemical arrangements of calcium-oxygen-carbon groups at the molecular level in TPI. The molecular models are based on graphene oxide nanostructures in which calcium cations are strongly adsorbed at the oxide sites. The application of material science techniques to the field of soil science facilitates a new level of understanding, providing insights into the structure and functionality of recalcitrant carbon in soil and its implications for food production and climate change.

  5. Traceable components of terrestrial carbon storage capacity in biogeochemical models.

    PubMed

    Xia, Jianyang; Luo, Yiqi; Wang, Ying-Ping; Hararuk, Oleksandra

    2013-07-01

    Biogeochemical models have been developed to account for more and more processes, making their complex structures difficult to be understood and evaluated. Here, we introduce a framework to decompose a complex land model into traceable components based on mutually independent properties of modeled biogeochemical processes. The framework traces modeled ecosystem carbon storage capacity (Xss ) to (i) a product of net primary productivity (NPP) and ecosystem residence time (τE ). The latter τE can be further traced to (ii) baseline carbon residence times (τ'E ), which are usually preset in a model according to vegetation characteristics and soil types, (iii) environmental scalars (ξ), including temperature and water scalars, and (iv) environmental forcings. We applied the framework to the Australian Community Atmosphere Biosphere Land Exchange (CABLE) model to help understand differences in modeled carbon processes among biomes and as influenced by nitrogen processes. With the climate forcings of 1990, modeled evergreen broadleaf forest had the highest NPP among the nine biomes and moderate residence times, leading to a relatively high carbon storage capacity (31.5 kg cm(-2) ). Deciduous needle leaf forest had the longest residence time (163.3 years) and low NPP, leading to moderate carbon storage (18.3 kg cm(-2) ). The longest τE in deciduous needle leaf forest was ascribed to its longest τ'E (43.6 years) and small ξ (0.14 on litter/soil carbon decay rates). Incorporation of nitrogen processes into the CABLE model decreased Xss in all biomes via reduced NPP (e.g., -12.1% in shrub land) or decreased τE or both. The decreases in τE resulted from nitrogen-induced changes in τ'E (e.g., -26.7% in C3 grassland) through carbon allocation among plant pools and transfers from plant to litter and soil pools. Our framework can be used to facilitate data model comparisons and model intercomparisons via tracking a few traceable components for all terrestrial carbon

  6. The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer

    USGS Publications Warehouse

    Kramer, Henry

    1956-01-01

    A method has been developed for the determination of calcium in phosphate, carbonate, and silicate rocks using the Beckman flame photometer, with photomultiplier attachement. The sample is dissolved in hydrofluoric, nitric, and perchloric acids, the hydrofluoric and nitric acids are expelled, a radiation buffer consisting of aluminum, magnesium, iron, sodium, potassium, phosphoric acid, and nitric acid is added, and the solution is atomized in an oxy-hydrogen flame with an instrument setting of 554 mµ. Measurements are made by comparison against calcium standards, prepared in the same manner, in the 0 to 50 ppm range. The suppression of calcium emission by aluminum and phosphate was overcome by the addition of a large excess of magnesium. This addition almost completely restores the standard curve obtained from a solution of calcium nitrate. Interference was noted when the iron concentration in the aspirated solution (including the iron from the buffer) exceeded 100 ppm iron. Other common rock-forming elements did not interfere. The results obtained by this procedure are within ± 2 percent of the calcium oxide values obtained by other methods in the range 1 to 95 percent calcium oxide. In the 0 to 1 percent calcium oxide range the method compares favorably with standard methods.

  7. Factors affecting ex-situ aqueous mineral carbonation using calcium and magnesium silicate minerals

    SciTech Connect

    Gerdemann, Stephen J.; Dahlin, David C.; O'Connor, William K.; Penner, Larry R.; Rush, G.E.

    2004-01-01

    Carbonation of magnesium- and calcium-silicate minerals to form their respective carbonates is one method to sequester carbon dioxide. Process development studies have identified reactor design as a key component affecting both the capital and operating costs of ex-situ mineral sequestration. Results from mineral carbonation studies conducted in a batch autoclave were utilized to design and construct a unique continuous pipe reactor with 100% recycle (flow-loop reactor). Results from the flow-loop reactor are consistent with batch autoclave tests, and are being used to derive engineering data necessary to design a bench-scale continuous pipeline reactor.

  8. Carbon Capture and Storage (CCS): Overview, Developments, and Challenges

    NASA Astrophysics Data System (ADS)

    Busch, Andreas; Amann, Alexandra; Kronimus, Alexander; Kühn, Michael

    2010-05-01

    Carbon dioxide capture and storage (CCS) is a technology that will allow the continued combustion of fossil fuels (coal, oil, gas) for e.g. power generation, transportation and industrial processes for the next decades. It therefore facilitates to bridge to a more renewable energy dominated world, enhances the stability and security of energy systems and at the same time reduces global carbon emissions as manifested by many western countries. Geological media suitable for CO2 storage are mainly saline aquifers due to the large storage volumes associated with them, but also depleted oil and gas reservoirs or deep unminable coal beds. Lately, CO2 storage into mafic- to ultramafic rocks, associated with subsequent mineral carbonation are within the R&D scope and first demonstration projects are being executed. For all these storage options various physical and chemical trapping mechanisms must reveal the necessary capacity and injectivity, and must confine the CO2 both, vertically (through an effective seal) or horizontally (through a confining geological structure). Confinement is the prime prerequisite to prevent leakage to other strata, shallow potable groundwater, soils and/or atmosphere. Underground storage of gases (e.g. CO2, H2S, CH4) in these media has been demonstrated on a commercial scale by enhanced oil recovery operations, natural gas storage and acid gas disposal. Some of the risks associated with CO2 capture and geological storage are comparable with any of these industrial activities for which extensive safety and regulatory frameworks are in place. Specific risks associated with CO2 storage relate to the operational (injection) phase and to the post-operational phase. In both phases the risks of most concern are those posed by the potential for acute or chronic CO2 leakage from the storage site. Currently there are only few operations worldwide where CO2 is injected and stored in the subsurface. Some are related to oil production enhancement but the

  9. Effect of calcium carbonate on the compliance of an apatitic calcium phosphate bone cement.

    PubMed

    Khairoun, I; Boltong, M G; Driessens, F C; Planell, J A

    1997-12-01

    Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time and the ultimate compressive strength. Three cement formulations were tested. The previously developed Biocement H was made of a powder containing alpha-tertiary calcium phosphate and precipitated hydroxyapatite. Biocement B2 powder was made by adding some CaCO3 to Biocement H, whereas Biocement B1 was made by adding some CaCO3 but with simultaneous adjustment of the amount of precipitated hydroxyapatite.The liquid/ powder ratio of the cement paste and the accelerator concentrations (percentage Na2HPO4) in cement liquid were varied. For Biocement H there was no combination of L/P ratio and percentage Na2HPO4 for which all clinical requirements were satisfied. However, there was an area of full compliance for Biocements B1 and B2, of which that for B1 was the largest. Therefore, Biocement B1 may be applied in clinical situations as those in orthopaedics, plastic and reconstructive surgery and oral and maxillofacial surgery, even when early contact with blood is inevitable.

  10. Constant-distance mode scanning potentiometry. 1. Visualization of calcium carbonate dissolution in aqueous solution.

    PubMed

    Etienne, Mathieu; Schulte, Albert; Mann, Stefan; Jordan, Guntram; Dietzel, Irmgard D; Schuhmann, Wolfgang

    2004-07-01

    Constant-distance mode scanning potentiometry was established by integrating potentiometric microsensors as ion-selective scanning probes into a SECM setup that was equipped with a piezoelectric shear force-based tip-to-sample distance control. The combination of specially designed micrometer-sized potentiometric tips with an advanced system for tip positioning allowed simultaneous acquisition of both topographic and potentiometric information at solid/liquid interfaces with high spatial resolution. The performance of the approach was evaluated by applying Ca(2+)-selective constant-distance mode potentiometry to monitor the dissolution of calcium carbonate occurring either at the (104) surface of calcite crystals or in proximity to the more complex surface of cross sections of a calcium carbonate shell of Mya arenaria exposed to slightly acidic aqueous solutions. Micrometer-scale heterogeneities in the apparent calcium activity profiles have successfully been resolved for both samples.

  11. Evidence for Calcium Carbonate at the Phoenix Landing Site

    NASA Technical Reports Server (NTRS)

    Boynton, W. V.; Ming, D. W.; Sutter, B.; Arvidson, R. E.; Hoffman, J.; Niles, P. B.; Smith, P.

    2009-01-01

    The Phoenix mission has recently finished its study of the north polar environment of Mars with the aim to help understand both the current climate and to put constraints on past climate. An important part of understanding the past climate is the study of secondary minerals, those formed by reaction with volatile compounds such as H2O and CO2. This work describes observations made by the Thermal and Evolved-Gas Analyzer (TEGA) on the Phoenix Lander related to carbonate minerals. Carbonates are generally considered to be products of aqueous processes. A wet and warmer climate during the early history of Mars coupled with a much denser CO2 atmosphere are ideal conditions for the aqueous alteration of basaltic materials and the subsequent formation of carbonates. Carbonates (Mg- and Ca-rich) are predicted to be thermodynamically stable minerals in the present martian environment, however, there have been only a few indications of carbonates on the surface by a host of orbiting and landed missions to Mars. Carbonates (Mg-rich) have been suggested to be a component (2-5 wt %) of the martian global dust based upon orbital thermal emission spectroscopy. The identifications, based on the presence of a 1480 cm-1 absorption feature, are consistent with Mgcarbonates. A similar feature is observed in brighter, undisturbed soils by Mini-TES on the Gusev plains. Recently, Mg-rich carbonates have been identified in the Nili Fossae region by the CRISM instrument onboard the Mars Reconnaissance Orbiter. Carbonates have also been confirmed as aqueous alteration phases in martian meteorites so it is puzzling why there have not been more discoveries of carbonates by landers, rovers, and orbiters. Carbonates may hold important clues about the history of liquid water and aqueous processes on the surface of Mars.

  12. [Contribution of tropical upland forests to carbon storage in Colombia].

    PubMed

    Yepes, Adriana; Herrera, Johana; Phillips, Juan; Galindo, Gustavo; Granados, Edwin; Duque, Alvaro; Barbosa, Adriana; Olarte, Claudia; Cardona, María

    2015-03-01

    The tropical montane forests in the Colombian Andean region are located above 1500 m, and have been heavily deforested. Despite the general presumption that productivity and hence carbon stocks in these ecosystems are low, studies in this regard are scarce. This study aimed to (i) to estimate Above Ground Biomass (AGB) in forests located in the South of the Colombian Andean region, (ii) to identify the carbon storage potential of tropical montane forests dominated by the black oak Colombobalanus excelsa and to identify the relationship between AGB and altitude, and (iii) to analyze the role of tropical mountain forests in conservation mechanisms such as Payment for Environmental Services (PES) and Reducing Emissions from Deforestation and Degradation (REDD+). Twenty six 0.25 ha plots were randomly distributed in the forests and all trees with D > or =10 cm were measured. The results provided important elements for understanding the role of tropical montane forests as carbon sinks. The information produced can be used in subnational initiatives, which seek to mitigate or reduce the effects of deforestation through management or conservation of these ecosystems, like REDD+ or PES. The AGB and carbon stocks results obtained were similar to those reported for lowland tropical forests. These could be explained by the dominance and abundance of C. excelsa, which accounted for over 81% of AGB/carbon. The error associated with the estimates of AGB/carbon was 10.58%. We found a negative and significant relationship between AGB and altitude, but the higher AGB values were in middle altitudes (approximatly = 700-1800 m), where the environmental conditions could be favorable to their growth. The carbon storage potential of these forests was higher. However, if the historical rate of the deforestation in the study area continues, the gross emissions of CO2e to the atmosphere could turn these forests in to an important emissions source. Nowadays, it is clear that tropical

  13. [Study on solid dispersion of precipitated calcium carbonate-based oleanolic acid].

    PubMed

    Yan, Hong-mei; Zhang, Zhen-hai; Jia, Xiao-bin; Jiang, Yan-rong; Sun, E

    2015-05-01

    Oleanolic acid-precipitated calcium carbonate solid dispersion was prepared by using solvent evaporation method. The microscopic structure and physicochemical properties of solid dispersion were analyzed using differential scanning calorimetry and scanning electron microscopy (SEM). And its in vitro release also was investigated. The properties of the precipitated calcium carbonate was studied which was as a carrier of oleanolic acid solid dispersion. Differential scanning calorimetry analysis suggested that oleanolic acid may be present in solid dispersion as amorphous substance. The in vitro release determination results of oleanolic acid-precipitated calcium carbonate (1: 5) solid dispersion showed accumulated dissolution rate of.oleanolic acid was up to 90% at 45 min. Accelerating experiment showed that content and in vitro dissolution of oleanolic acid solid dispersion did not change after storing over 6 months. The results indicated that in vitro dissolution of oleanolic acid was improved greatly by the solid dispersion with precipitated calcium carbonate as a carrier. The solid dispersion is a stabilizing system which has actual applied value.

  14. Coexistence of three calcium carbonate polymorphs in the shell of the Antarctic clam Laternula elliptica

    NASA Astrophysics Data System (ADS)

    Nehrke, Gernot; Poigner, Harald; Wilhelms-Dick, Dorothee; Brey, Thomas; Abele, Doris

    2012-05-01

    We analyzed shell cuts of five individuals of the Antarctic bivalve Laternula elliptica from three locations along the Antarctic Peninsula by means of Confocal Raman Microscopy (CRM) as well as Electron Microprobe (EMP). The shell of L. elliptica has been previously described as being composed of aragonite exclusively. Now, CRM mapping reveals that three polymorphs of calcium carbonate - aragonite, calcite, and vaterite - are present in the chondrophore region of the examined individuals. Annual shell growth layers continue through aragonite and vaterite, suggesting simultaneous mineralization of both polymorphs. Spatially congruent EMP scans showed that the calcium carbonate polymorph affects the distribution of magnesium and strontium within the chondrophore. This is, to our knowledge, the first report of the coexistence of these three calcium carbonate polymorphs within the mineralized structures of a marine calcifying organism. Particularly the presence of vaterite is unexpected, but shows striking similarities to some fish otoliths. The strong effect of the calcium carbonate polymorph on trace element incorporation restrict the suitability of magnesium and strontium based proxies for the chondrophore area of L. elliptica.

  15. Ethanol assisted synthesis of pure and stable amorphous calcium carbonate nanoparticles.

    PubMed

    Chen, Shao-Feng; Cölfen, Helmut; Antonietti, Markus; Yu, Shu-Hong

    2013-10-25

    Stable monodispersed amorphous calcium carbonate (ACC) nanoparticles can be synthesized in ethanol media by a facile method, and crystallization of ACC is kinetically controlled, resulting in the formation of three polymorphs in a mixed solvent of ethanol-water at different pH values.

  16. Growth of calcium carbonate crystals on the European Retrievable carrier flight

    NASA Astrophysics Data System (ADS)

    Nielsen, K. F.; Lind, M. D.; Lindegaard-Andersen, A.; Gerward, L.; Groth-Andersen, L.

    1995-08-01

    On the Solution Growth Facility (SGF) of the European Retrievable Carrier (EURECA), clear, colorless crystals of calcium carbonate up to 3 mm long have been grown from aqueous solution without the use of a gel. This is a much improved result compared with previous solution growth of CaCO_3.

  17. Carbon-based electrocatalysts for advanced energy conversion and storage

    PubMed Central

    Zhang, Jintao; Xia, Zhenhai; Dai, Liming

    2015-01-01

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries. Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries. We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance. PMID:26601241

  18. Carbon-based electrocatalysts for advanced energy conversion and storage.

    PubMed

    Zhang, Jintao; Xia, Zhenhai; Dai, Liming

    2015-08-01

    Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play curial roles in electrochemical energy conversion and storage, including fuel cells and metal-air batteries. Having rich multidimensional nanoarchitectures [for example, zero-dimensional (0D) fullerenes, 1D carbon nanotubes, 2D graphene, and 3D graphite] with tunable electronic and surface characteristics, various carbon nanomaterials have been demonstrated to act as efficient metal-free electrocatalysts for ORR and OER in fuel cells and batteries. We present a critical review on the recent advances in carbon-based metal-free catalysts for fuel cells and metal-air batteries, and discuss the perspectives and challenges in this rapidly developing field of practical significance. PMID:26601241

  19. Novel Carbons as Electrodes for Electrical Energy Storage

    NASA Astrophysics Data System (ADS)

    Ruoff, Rodney S.

    2014-03-01

    In this talk I will speculate about directions for carbon materials as the electrode(s) in EES systems such as ultracapacitors and Li ion batteries. Perhaps the penultimate electrode material for ultracapacitors (based on charge storage by electrical double layer capacitance, EDLC) would be a ``negative curvature carbon'' (NCC, akin to the Schwartzite structures) with atom thick walls, and possibly substitutionally doped with, e.g., N atoms in case the all-carbon structure were limited by quantum (i.e., intrinsic) capacitance. Such an NCC would have a distribution of pore sizes that would likely (for optimal performance) span ``mesoscale'' and ``microscale'' pores, which in the parlance of porous materials means pores ``above 2-3 nanometers'' and pores ``below about 2 nanometers,'' respectively. Making such materials offers exciting challenges for materials chemists/synthetic chemists, and to date only the ``basic'' Schwarzite structures (ideal crystals studied by DFT with periodic boundary conditions and relatively simple unit cells) have been modeled in terms of properties such as their electronic states and in some cases, potential as all carbon ferromagnets. I identified the NCCs as candidates for EES for ultracapacitors, in a paper published in Science in 2011 with coauthors. We made an aperiodic carbon that had atom thick walls and surface areas as high as 3200 m2/g, along with ``good'' powder electrical conductivity, high carbon content, and apparently close to 100% trivalently bonded carbon in the walls of this very porous carbon. We have learned in one set of experiments, as published in Energy and Environmental Science, that doping with N atoms can increase the EDLC, which we suggest could be a consequence of limiting quantum capacitance in the all-carbon analogue.

  20. Electron and phonon properties and gas storage in carbon honeycombs

    NASA Astrophysics Data System (ADS)

    Gao, Yan; Chen, Yuanping; Zhong, Chengyong; Zhang, Zhongwei; Xie, Yuee; Zhang, Shengbai

    2016-06-01

    A new kind of three-dimensional carbon allotrope, termed carbon honeycomb (CHC), has recently been synthesized [PRL 116, 055501 (2016)]. Based on the experimental results, a family of graphene networks has been constructed, and their electronic and phonon properties are studied by various theoretical approaches. All networks are porous metals with two types of electron transport channels along the honeycomb axis and they are isolated from each other: one type of channel originates from the orbital interactions of the carbon zigzag chains and is topologically protected, while the other type of channel is from the straight lines of the carbon atoms that link the zigzag chains and is topologically trivial. The velocity of the electrons can reach ~106 m s-1. Phonon transport in these allotropes is strongly anisotropic, and the thermal conductivities can be very low when compared with graphite by at least a factor of 15. Our calculations further indicate that these porous carbon networks possess high storage capacity for gaseous atoms and molecules in agreement with the experiments.A new kind of three-dimensional carbon allotrope, termed carbon honeycomb (CHC), has recently been synthesized [PRL 116, 055501 (2016)]. Based on the experimental results, a family of graphene networks has been constructed, and their electronic and phonon properties are studied by various theoretical approaches. All networks are porous metals with two types of electron transport channels along the honeycomb axis and they are isolated from each other: one type of channel originates from the orbital interactions of the carbon zigzag chains and is topologically protected, while the other type of channel is from the straight lines of the carbon atoms that link the zigzag chains and is topologically trivial. The velocity of the electrons can reach ~106 m s-1. Phonon transport in these allotropes is strongly anisotropic, and the thermal conductivities can be very low when compared with graphite by

  1. Carbon sequestration kinetic and storage capacity of ultramafic mining waste.

    PubMed

    Pronost, Julie; Beaudoin, Georges; Tremblay, Joniel; Larachi, Faïçal; Duchesne, Josée; Hébert, Réjean; Constantin, Marc

    2011-11-01

    Mineral carbonation of ultramafic rocks provides an environmentally safe and permanent solution for CO(2) sequestration. In order to assess the carbonation potential of ultramafic waste material produced by industrial processing, we designed a laboratory-scale method, using a modified eudiometer, to measure continuous CO(2) consumption in samples at atmospheric pressure and near ambient temperature. The eudiometer allows monitoring the CO(2) partial pressure during mineral carbonation reactions. The maximum amount of carbonation and the reaction rate of different samples were measured in a range of experimental conditions: humidity from dry to submerged, temperatures of 21 and 33 °C, and the proportion of CO(2) in the air from 4.4 to 33.6 mol %. The most reactive samples contained ca. 8 wt % CO(2) after carbonation. The modal proportion of brucite in the mining residue is the main parameter determining maximum storage capacity of CO(2). The reaction rate depends primarily on the proportion of CO(2) in the gas mixture and secondarily on parameters controlling the diffusion of CO(2) in the sample, such as relative saturation of water in pore space. Nesquehonite was the dominant carbonate for reactions at 21 °C, whereas dypingite was most common at 33 °C.

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

    USGS Publications Warehouse

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

    1996-01-01

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

  3. Measurement of carbon storage in landfills from the biogenic carbon content of excavated waste samples.

    PubMed

    De la Cruz, Florentino B; Chanton, Jeffrey P; Barlaz, Morton A

    2013-10-01

    Landfills are an anaerobic ecosystem and represent the major disposal alternative for municipal solid waste (MSW) in the U.S. While some fraction of the biogenic carbon, primarily cellulose (Cel) and hemicellulose (H), is converted to carbon dioxide and methane, lignin (L) is essentially recalcitrant. The biogenic carbon that is not mineralized is stored within the landfill. This carbon storage represents a significant component of a landfill carbon balance. The fraction of biogenic carbon that is not reactive in the landfill environment and therefore stored was derived for samples of excavated waste by measurement of the total organic carbon, its biogenic fraction, and the remaining methane potential. The average biogenic carbon content of the excavated samples was 64.6±18.0% (average±standard deviation), while the average carbon storage factor was 0.09±0.06g biogenic-C stored per g dry sample or 0.66±0.16g biogenic-C stored per g biogenic C.

  4. Carbon dioxide transport in molten calcium carbonate occurs through an oxo-Grotthuss mechanism via a pyrocarbonate anion.

    PubMed

    Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

    2016-05-01

    The reactivity, speciation and solvation structure of CO2 in carbonate melts are relevant for both the fate of carbon in deep geological formations and for its electroreduction to CO (to be used as fuel) when solvated in a molten carbonate electrolyte. In particular, the high solubility of CO2 in carbonate melts has been tentatively attributed to the formation of the pyrocarbonate anion, C2O5(2-). Here we study, by first-principles molecular dynamics simulations, the behaviour of CO2 in molten calcium carbonate. We find that pyrocarbonate forms spontaneously and the identity of the CO2 molecule is quickly lost through O(2-) exchange. The transport of CO2 in this molten carbonate thus occurs in a fashion similar to the Grotthuss mechanism in water, and is three times faster than molecular diffusion. This shows that Grotthuss-like transport is more general than previously thought. PMID:27102679

  5. Carbon dioxide transport in molten calcium carbonate occurs through an oxo-Grotthuss mechanism via a pyrocarbonate anion

    NASA Astrophysics Data System (ADS)

    Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

    2016-05-01

    The reactivity, speciation and solvation structure of CO2 in carbonate melts are relevant for both the fate of carbon in deep geological formations and for its electroreduction to CO (to be used as fuel) when solvated in a molten carbonate electrolyte. In particular, the high solubility of CO2 in carbonate melts has been tentatively attributed to the formation of the pyrocarbonate anion, C2O52–. Here we study, by first-principles molecular dynamics simulations, the behaviour of CO2 in molten calcium carbonate. We find that pyrocarbonate forms spontaneously and the identity of the CO2 molecule is quickly lost through O2– exchange. The transport of CO2 in this molten carbonate thus occurs in a fashion similar to the Grotthuss mechanism in water, and is three times faster than molecular diffusion. This shows that Grotthuss-like transport is more general than previously thought.

  6. Amorphous calcium carbonate controls avian eggshell mineralization: A new paradigm for understanding rapid eggshell calcification.

    PubMed

    Rodríguez-Navarro, Alejandro B; Marie, Pauline; Nys, Yves; Hincke, Maxwell T; Gautron, Joel

    2015-06-01

    Avian eggshell mineralization is the fastest biogenic calcification process known in nature. How this is achieved while producing a highly crystalline material composed of large calcite columnar single crystals remains largely unknown. Here we report that eggshell mineral originates from the accumulation of flat disk-shaped amorphous calcium carbonate (ACC) particles on specific organic sites on the eggshell membrane, which are rich in proteins and sulfated proteoglycans. These structures known as mammillary cores promote the nucleation and stabilization of a amorphous calcium carbonate with calcitic short range order which predetermine the calcite composition of the mature eggshell. The amorphous nature of the precursor phase was confirmed by the diffuse scattering of X-rays and electrons. The nascent calcitic short-range order of this transient mineral phase was revealed by infrared spectroscopy and HRTEM. The ACC mineral deposited around the mammillary core sites progressively transforms directly into calcite crystals without the occurrence of any intermediate phase. Ionic speciation data suggest that the uterine fluid is equilibrated with amorphous calcium carbonate, throughout the duration of eggshell mineralization process, supporting that this mineral phase is constantly forming at the shell mineralization front. On the other hand, the transient amorphous calcium carbonate mineral deposits, as well as the calcite crystals into which they are converted, form by the ordered aggregation of nanoparticles that support the rapid mineralization of the eggshell. The results of this study alter our current understanding of avian eggshell calcification and provide new insights into the genesis and formation of calcium carbonate biominerals in vertebrates.

  7. Progress and new developments in carbon capture and storage

    SciTech Connect

    Plasynski, S.I.; Litynski, J.T.; McIlvried, H.G.; Srivastava, R.D.

    2009-07-01

    Growing concern over the impact on global climate change of the buildup of greenhouse gases (GHGs) in the atmosphere has resulted in proposals to capture carbon dioxide (CO{sub 2}) at large point sources and store it in geologic formations, such as oil and gas reservoirs, unmineable coal seams, and saline formations, referred to as carbon capture and storage (CCS). There are three options for capturing CO{sub 2} from point sources: post-combustion capture, pre-combustion capture, and oxy-combustion. Several processes are available to capture CO{sub 2}, and new or improved processes are under development. However, CO{sub 2} capture is the most expensive part of CCS, typically accounting for 75% of overall cost. CCS will benefit significantly from the development of a lower cost post-combustion CO{sub 2} capture process that can be retrofitted to existing power plants. Once captured, the CO{sub 2} is compressed to about 150 atm and pipelined at supercritical conditions to a suitable storage site. Oil and gas reservoirs, because they have assured seals and are well characterized, are promising early opportunity sites. Saline formations are much more extensive and have a huge potential storage capacity, but are much less characterized. Several commercial and a number of pilot CCS projects are underway around the world.

  8. Lithium storage on carbon nitride, graphenylene and inorganic graphenylene.

    PubMed

    Hankel, Marlies; Searles, Debra J

    2016-06-01

    We present results of density functional theory calculations on the lithium (Li) ion storage capacity of three different two dimensional porous graphene-like membranes. The graphitic carbon nitride membrane, g-CN, is found to have a large Li storage capacity of at least 813 mA h g(-1) (LiCN). However, it is also found that the Li interacts very strongly with the membrane indicating that this is most likely irreversible. According to the calculations, graphenylene or biphenylene carbon (BPC) has a storage capacity of 487 mA h g(-1) (Li1.5C6) which is higher than that for graphite. We also find that Li is very mobile on these materials and does not interact as strongly with the membrane making it a more suitable anode material. Inorganic graphenylene, which is a boron nitride analog of graphenylene, shows very low binding energies, much lower than the cohesive energy of lithium, and it appears to be unsuitable as an anode material for lithium ion batteries. We discuss how charge transfer leads to the very different behaviour observed in these three similar materials.

  9. Calcium carbonate mineralization: involvement of extracellular polymeric materials isolated from calcifying bacteria.

    PubMed

    Ercole, Claudia; Bozzelli, Paola; Altieri, Fabio; Cacchio, Paola; Del Gallo, Maddalena

    2012-08-01

    This study highlights the role of specific outer bacterial structures, such as the glycocalix, in calcium carbonate crystallization in vitro. We describe the formation of calcite crystals by extracellular polymeric materials, such as exopolysaccharides (EPS) and capsular polysaccharides (CPS) isolated from Bacillus firmus and Nocardia calcarea. Organic matrices were isolated from calcifying bacteria grown on synthetic medium--in the presence or absence of calcium ions--and their effect on calcite precipitation was assessed. Scanning electron microscopy observations and energy dispersive X-ray spectrometry analysis showed that CPS and EPS fractions were involved in calcium carbonate precipitation, not only serving as nucleation sites but also through a direct role in crystal formation. The utilization of different synthetic media, with and without addition of calcium ions, influenced the biofilm production and protein profile of extracellular polymeric materials. Proteins of CPS fractions with a molecular mass between 25 and 70 kDa were overexpressed when calcium ions were present in the medium. This higher level of protein synthesis could be related to the active process of bioprecipitation.

  10. Effects of Sevelamer Hydrochloride and Calcium Carbonate on Renal Osteodystrophy in Hemodialysis Patients

    PubMed Central

    Ferreira, Aníbal; Frazão, João Miguel; Monier-Faugere, Marie-Claude; Gil, Célia; Galvao, José; Oliveira, Carlos; Baldaia, Jorge; Rodrigues, Ilidio; Santos, Carla; Ribeiro, Silvia; Hoenger, Regula Mueller; Duggal, Ajay; Malluche, Hartmut H.

    2008-01-01

    Disturbances in mineral metabolism play a central role in the development of renal bone disease. In a 54-wk, randomized, open-label study, 119 hemodialysis patients were enrolled to compare the effects of sevelamer hydrochloride and calcium carbonate on bone. Biopsy-proven adynamic bone disease was the most frequent bone abnormality at baseline (59%). Serum phosphorus, calcium, and intact parathyroid hormone were well controlled in both groups, although calcium was consistently lower and intact parathyroid hormone higher among patients who were randomly assigned to sevelamer. Compared with baseline values, there were no changes in mineralization lag time or measures of bone turnover (e.g., activation frequency) after 1 yr in either group. Osteoid thickness significantly increased in both groups, but there was no significant difference between them. Bone formation rate per bone surface, however, significantly increased from baseline only in the sevelamer group (P = 0.019). In addition, of those with abnormal microarchitecture at baseline (i.e., trabecular separation), seven of 10 in the sevelamer group normalized after 1 yr compared with zero of three in the calcium group. In summary, sevelamer resulted in no statistically significant changes in bone turnover or mineralization compared with calcium carbonate, but bone formation increased and trabecular architecture improved with sevelamer. Further studies are required to assess whether these changes affect clinical outcomes, such as rates of fracture. PMID:18199805

  11. Calcium carbonate mineralization: involvement of extracellular polymeric materials isolated from calcifying bacteria.

    PubMed

    Ercole, Claudia; Bozzelli, Paola; Altieri, Fabio; Cacchio, Paola; Del Gallo, Maddalena

    2012-08-01

    This study highlights the role of specific outer bacterial structures, such as the glycocalix, in calcium carbonate crystallization in vitro. We describe the formation of calcite crystals by extracellular polymeric materials, such as exopolysaccharides (EPS) and capsular polysaccharides (CPS) isolated from Bacillus firmus and Nocardia calcarea. Organic matrices were isolated from calcifying bacteria grown on synthetic medium--in the presence or absence of calcium ions--and their effect on calcite precipitation was assessed. Scanning electron microscopy observations and energy dispersive X-ray spectrometry analysis showed that CPS and EPS fractions were involved in calcium carbonate precipitation, not only serving as nucleation sites but also through a direct role in crystal formation. The utilization of different synthetic media, with and without addition of calcium ions, influenced the biofilm production and protein profile of extracellular polymeric materials. Proteins of CPS fractions with a molecular mass between 25 and 70 kDa were overexpressed when calcium ions were present in the medium. This higher level of protein synthesis could be related to the active process of bioprecipitation. PMID:22697480

  12. Climatically driven loss of calcium in steppe soil as a sink for atmospheric carbon

    USGS Publications Warehouse

    Lapenis, A.G.; Lawrence, G.B.; Bailey, S.W.; Aparin, B.F.; Shiklomanov, A.I.; Speranskaya, N.A.; Torn, M.S.; Calef, M.

    2008-01-01

    During the last several thousand years the semi-arid, cold climate of the Russian steppe formed highly fertile soils rich in organic carbon and calcium (classified as Chernozems in the Russian system). Analysis of archived soil samples collected in Kemannaya Steppe Preserve in 1920, 1947, 1970, and fresh samples collected in 1998 indicated that the native steppe Chernozems, however, lost 17-28 kg m-2 of calcium in the form of carbonates in 1970-1998. Here we demonstrate that the loss of calcium was caused by fundamental shift in the steppe hydrologic balance. Previously unleached soils where precipitation was less than potential evapotranspiration are now being leached due to increased precipitation and, possibly, due to decreased actual evapotranspiration. Because this region receives low levels of acidic deposition, the dissolution of carbonates involves the consumption of atmospheric CO2. Our estimates indicate that this climatically driven terrestrial sink of atmospheric CO2 is ???2.1-7.4 g C m-2 a-1. In addition to the net sink of atmospheric carbon, leaching of pedogenic carbonates significantly amplified seasonal amplitude of CO2 exchange between atmosphere and steppe soil. Copyright 2008 by the American Geophysical Union.

  13. Nanoscale analysis of the morphology and surface stability of calcium carbonate polymorphs

    NASA Astrophysics Data System (ADS)

    Sekkal, W.; Zaoui, A.

    2013-04-01

    Under earth surface conditions, in ocean and natural water, calcium carbonate is ubiquitous, forming anhydrous and hydrous minerals. These hydrous phases are of considerable interest for their role as precursors to stable carbonate minerals. Atomistic simulation techniques have been employed here to perform a comprehensive and quantitative study of the structural and energetic stability of dry and hydrous surfaces of calcium carbonate polymorphs using two recently developed forcefields. Results show that the dry forms are prone to ductility; while hydrous phases are found to be brittle. The (001) surface of monohydrocalcite appears to be the most stable (0.99 J/m2) whereas for the ikaite phase, the (001) surface is the most stable. The corresponding value is 0.2 J/m2, i.e. even lower than the surface energy of the Beautiful computed morphology pictures are obtained with Xiao's model and are very similar to the observed SEM images.

  14. Water availability and calcium propionate affect fungal population and aflatoxins production in broiler finisher feed during storage.

    PubMed

    Alam, Sahib; Shah, Hamid Ullah; Khan, Nazir Ahmad; Zeb, Alam; Shah, Abdul Sattar; Magan, Naresh

    2014-01-01

    The aim of this study was to investigate the effects of calcium propionate, water activity (aw) and incubation time on the total fungal count and aflatoxins B₁ (AFB₁), B₂ (AFB₂), G₁ (AFG₁) and G₂ (AFG₂) production in the broiler finisher feed. The feed was added with calcium propionate (5 g kg(-1)), adjusted to 0.85, 0.90 and 0.95 aw and stored for 28 days at 25°C, analysing for mould growth and aflatoxins production every 7 days. Analysis of variance indicated that all the factors (preservative, aw and storage time) alone and in combination significantly (p < 0.001) affected the total fungal count and aflatoxins production in the feed. Minimum total fungal counts (1.99 × 10(2) CFU g(-1)) were observed in calcium propionate feed at 0.85 aw on day 1 and the highest (4.36 × 10(9) CFUs g(-1)) in control sample at 0.95 aw on day 28 of storage. During the storage period, AFB₁ content in control samples increased from 11.35 to 73.44, from 11.58 to 81.81 and from 11.54 to 102.68 ng g(-1), whereas in preserved feed the content of B₁ increased from 11.47 to 37.83, from 11.54 to 49.07 and from 11.20 to 53.14 ng g(-1) at 0.85, 0.90 and 0.95 aw, respectively. Similar patterns were noted for AFB2, AFG₁ and AFG₂ contents. All the aflatoxins readily increased over storage time; however, the increase was much slower in preserved feed that contained a lower amount of available water. This study reveals that calcium propionate addition to poultry litter along with water activity amelioration is an effective tool for controlling mould incidence and aflatoxin production in poultry feed.

  15. ATP-stabilized amorphous calcium carbonate nanospheres and their application in protein adsorption.

    PubMed

    Qi, Chao; Zhu, Ying-Jie; Lu, Bing-Qiang; Zhao, Xin-Yu; Zhao, Jing; Chen, Feng; Wu, Jin

    2014-05-28

    Calcium carbonate is a common substance found in rocks worldwide, and is the main biomineral formed in shells of marine organisms and snails, pearls and eggshells. Amorphous calcium carbonate (ACC) is the least stable polymorph of calcium carbonate, which is so unstable under normal conditions that it is difficult to be prepared in vitro because it rapidly crystallizes to form one of the more stable polymorphs in aqueous solution. Herein, we report the successful synthesis of highly stable ACC nanospheres in vitro using adenosine 5'-triphosphate disodium salt (ATP) as a stabilizer. The effect of ATP on the stability of ACC nanospheres is investigated. Our experiments show that ATP plays an unique role in the stabilization of ACC nanospheres in aqueous solution. Moreover, the as-prepared ACC nanospheres are highly stable in phosphate buffered saline for a relatively long period of time (12 days) even under relatively high concentrations of calcium and phosphate ions. The cytotoxicity tests show that the as-prepared highly stable ACC nanospheres have excellent biocompatibility. The highly stable ACC nanospheres have high protein adsorption capacity, implying that they are promising for applications in biomedical fields such as drug delivery and protein adsorption.

  16. Characterization of calcium carbonate crystals in pigeon yolk sacs with different incubation times.

    PubMed

    Song, Juan; Cheng, Haixia; Shen, Xinyu; Hu, Jingxiao; Tong, Hua

    2014-05-01

    Calcium carbonate crystals are known to form in the yolk sacs of fertile pigeon eggs at late stages of incubation. The composition and structure of these crystals were investigated, the crystallization environment was inspected, and the physical chemistry constants of the yolk fluid were determined through the incubation period. Polarized light microscopy was used to observe the generation and distribution of calcium carbonate crystals in the yolk sac. In addition, X-ray diffraction was employed to analyze the composition and crystal phase of the yolk sac. A decalcification and deproteination method was established to analyze the ultrastructure and composition of the crystals, as well as the internal relationship between inorganic and organic phases of the crystals. Additionally, scanning electron microscopy, transmission electron microscopy, X-ray energy dispersive spectroscopy, and Fourier transform infrared spectroscopy were used to evaluate the characteristics of the crystals. Our results demonstrated that the calcium carbonate crystals were mainly composed of vaterite and calcite, with vaterite being the major component. Vaterite, a type of biomaterial generated by an organic template control, presented as a concentric hierarchical spherical structure. The organic nature of the biomaterial prevented vaterite from transforming into calcite, which is more thermodynamically stable than vaterite. Additionally, the configuration, size, and aggregation of vaterite were also mediated by the organic template. This bio-vaterite was found during the incubation period and is valuable in calcium transport during embryonic development.

  17. Complexation/encapsulation of green tea polyphenols in mixed calcium carbonate and phosphate micro-particles.

    PubMed

    Elabbadi, Amal; Jeckelmann, Nicolas; Haefliger, Olivier P; Ouali, Lahoussine

    2011-01-01

    We used a double-jet mixer to encapsulate water-soluble polyphenols, green tea extract (GTE), with calcium-based inorganic materials. The device mixed calcium chloride solutions with a solution of carbonate and phosphate in the presence of a GTE solution, and formed micro-particles which capture the GTE molecules. The micro-particles were analysed by liquid chromatography coupled to tandem mass spectroscopy to determine the encapsulation yield and loading of the different GTE components. We established correlations between (1) the efficiency of the GTE encapsulation and the composition of the mixed anion solutions and (2) the protonation degree of the ions and the molar ratio of calcium cations and carbonate/phosphate anions. An optimal and reproducible GTE loading of about 40% with an encapsulation yield of 65% was observed for a carbonate/phosphate molar composition of 4 : 1. In addition, our experimental results showed that the process is selective and favours the encapsulation of gallated species which form stronger complexes with calcium cations. PMID:20945969

  18. Soil Carbon Storage in Christmas Tree Farms: Maximizing Ecosystem Management and Sustainability for Carbon Sequestration

    NASA Astrophysics Data System (ADS)

    Chapman, S. K.; Shaw, R.; Langley, A.

    2008-12-01

    Management of agroecosystems for the purpose of manipulating soil carbon stocks could be a viable approach for countering rising atmospheric carbon dioxide concentrations, while maximizing sustainability of the agroforestry industry. We investigated the carbon storage potential of Christmas tree farms in the southern Appalachian mountains as a potential model for the impacts of land management on soil carbon. We quantified soil carbon stocks across a gradient of cultivation duration and herbicide management. We compared soil carbon in farms to that in adjacent pastures and native forests that represent a control group to account for variability in other soil-forming factors. We partitioned tree farm soil carbon into fractions delineated by stability, an important determinant of long-term sequestration potential. Soil carbon stocks in the intermediate pool are significantly greater in the tree farms under cultivation for longer periods of time than in the younger tree farms. This pool can be quite large, yet has the ability to repond to biological environmental changes on the centennial time scale. Pasture soil carbon was significantly greater than both forest and tree farm soil carbon, which were not different from each other. These data can help inform land management and soil carbon sequestration strategies.

  19. Influence of substrate mineralogy on bacterial mineralization of calcium carbonate: implications for stone conservation.

    PubMed

    Rodriguez-Navarro, Carlos; Jroundi, Fadwa; Schiro, Mara; Ruiz-Agudo, Encarnación; González-Muñoz, María Teresa

    2012-06-01

    The influence of mineral substrate composition and structure on bacterial calcium carbonate productivity and polymorph selection was studied. Bacterial calcium carbonate precipitation occurred on calcitic (Iceland spar single crystals, marble, and porous limestone) and silicate (glass coverslips, porous sintered glass, and quartz sandstone) substrates following culturing in liquid medium (M-3P) inoculated with different types of bacteria (Myxococcus xanthus, Brevundimonas diminuta, and a carbonatogenic bacterial community isolated from porous calcarenite stone in a historical building) and direct application of sterile M-3P medium to limestone and sandstone with their own bacterial communities. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), and 2-dimensional XRD (2D-XRD) analyses revealed that abundant highly oriented calcite crystals formed homoepitaxially on the calcitic substrates, irrespective of the bacterial type. Conversely, scattered spheroidal vaterite entombing bacterial cells formed on the silicate substrates. These results show that carbonate phase selection is not strain specific and that under equal culture conditions, the substrate type is the overruling factor for calcium carbonate polymorph selection. Furthermore, carbonate productivity is strongly dependent on the mineralogy of the substrate. Calcitic substrates offer a higher affinity for bacterial attachment than silicate substrates, thereby fostering bacterial growth and metabolic activity, resulting in higher production of calcium carbonate cement. Bacterial calcite grows coherently over the calcitic substrate and is therefore more chemically and mechanically stable than metastable vaterite, which formed incoherently on the silicate substrates. The implications of these results for technological applications of bacterial carbonatogenesis, including building stone conservation, are discussed.

  20. Influence of substrate mineralogy on bacterial mineralization of calcium carbonate: implications for stone conservation.

    PubMed

    Rodriguez-Navarro, Carlos; Jroundi, Fadwa; Schiro, Mara; Ruiz-Agudo, Encarnación; González-Muñoz, María Teresa

    2012-06-01

    The influence of mineral substrate composition and structure on bacterial calcium carbonate productivity and polymorph selection was studied. Bacterial calcium carbonate precipitation occurred on calcitic (Iceland spar single crystals, marble, and porous limestone) and silicate (glass coverslips, porous sintered glass, and quartz sandstone) substrates following culturing in liquid medium (M-3P) inoculated with different types of bacteria (Myxococcus xanthus, Brevundimonas diminuta, and a carbonatogenic bacterial community isolated from porous calcarenite stone in a historical building) and direct application of sterile M-3P medium to limestone and sandstone with their own bacterial communities. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), and 2-dimensional XRD (2D-XRD) analyses revealed that abundant highly oriented calcite crystals formed homoepitaxially on the calcitic substrates, irrespective of the bacterial type. Conversely, scattered spheroidal vaterite entombing bacterial cells formed on the silicate substrates. These results show that carbonate phase selection is not strain specific and that under equal culture conditions, the substrate type is the overruling factor for calcium carbonate polymorph selection. Furthermore, carbonate productivity is strongly dependent on the mineralogy of the substrate. Calcitic substrates offer a higher affinity for bacterial attachment than silicate substrates, thereby fostering bacterial growth and metabolic activity, resulting in higher production of calcium carbonate cement. Bacterial calcite grows coherently over the calcitic substrate and is therefore more chemically and mechanically stable than metastable vaterite, which formed incoherently on the silicate substrates. The implications of these results for technological applications of bacterial carbonatogenesis, including building stone conservation, are discussed. PMID:22447589

  1. A calcium oxide sorbent process for bulk separation of carbon dioxide

    SciTech Connect

    Harrison, D.P.

    1990-09-01

    This research effort is designed to investigate the technical feasibility of a high-temperature, high-pressure process for the bulk separation of CO{sub 2} from coal-derived gases. The two-year contract was awarded in September 1989. This report describes the research effort and results obtained during the first year of the effort. The overall project consists of 6 tasks, four of which were active during year 01. Tasks 1 and 2 were completed during the year while activity in Tasks 3 and 6 will carry over into year 02. Tasks 4 and 5 will be initiated during year 02. Three primary objectives were met in Task 1. A literature search on the calcination-carbonation reactions of CO{sub 2} with calcium-based sorbents was completed. A high temperature, high pressure (HTHP) electrobalance reactor suitable for studying the calcination and carbonation reactions was constructed. This reactor system is now fully operable and we are routinely collecting kinetics data at temperatures in the range of 550-900{degree}C and pressures of 1 to 15 atm. Samples of nine candidate calcium-based sorbents were acquired and tested. These samples were subjected to reaction screening tests as part of Task 2. As a result of these screening tests, chemically pure calcium carbonate, chemically pure calcium acetate, and the commercial dolomite were selected for more detailed kinetic testing. In Task 3, the HTHP electrobalance reactor is being used to study the calcination-carbonation behavior of the three base sorbents as a function of calcination temperature, carbonation temperature, carbonation pressure, and CO{sub 2} concentration.

  2. Influence of Substrate Mineralogy on Bacterial Mineralization of Calcium Carbonate: Implications for Stone Conservation

    PubMed Central

    Jroundi, Fadwa; Schiro, Mara; Ruiz-Agudo, Encarnación; González-Muñoz, María Teresa

    2012-01-01

    The influence of mineral substrate composition and structure on bacterial calcium carbonate productivity and polymorph selection was studied. Bacterial calcium carbonate precipitation occurred on calcitic (Iceland spar single crystals, marble, and porous limestone) and silicate (glass coverslips, porous sintered glass, and quartz sandstone) substrates following culturing in liquid medium (M-3P) inoculated with different types of bacteria (Myxococcus xanthus, Brevundimonas diminuta, and a carbonatogenic bacterial community isolated from porous calcarenite stone in a historical building) and direct application of sterile M-3P medium to limestone and sandstone with their own bacterial communities. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), and 2-dimensional XRD (2D-XRD) analyses revealed that abundant highly oriented calcite crystals formed homoepitaxially on the calcitic substrates, irrespective of the bacterial type. Conversely, scattered spheroidal vaterite entombing bacterial cells formed on the silicate substrates. These results show that carbonate phase selection is not strain specific and that under equal culture conditions, the substrate type is the overruling factor for calcium carbonate polymorph selection. Furthermore, carbonate productivity is strongly dependent on the mineralogy of the substrate. Calcitic substrates offer a higher affinity for bacterial attachment than silicate substrates, thereby fostering bacterial growth and metabolic activity, resulting in higher production of calcium carbonate cement. Bacterial calcite grows coherently over the calcitic substrate and is therefore more chemically and mechanically stable than metastable vaterite, which formed incoherently on the silicate substrates. The implications of these results for technological applications of bacterial carbonatogenesis, including building stone conservation, are discussed. PMID:22447589

  3. A comparative study on the lithium-ion storage performances of carbon nanotubes and tube-in-tube carbon nanotubes.

    PubMed

    Xu, Yi-Jun; Liu, Xi; Cui, Guanglei; Zhu, Bo; Weinberg, Gisela; Schlögl, Robert; Maier, Joachim; Su, Dang Sheng

    2010-03-22

    A comparative study of the electrochemical performances of carbon nanotubes and tube-in-tube carbon nanotubes reveals a dependence effect of lithium-ion storage behavior on the detailed nanostructure of carbon nanotubes. In particular, the impurity that graphitic particles or graphene fragments inherently present in carbon nanotubes plays a crucial role in the lithium-ion storage capacity of the carbon nanotubes. Compared to acid-washed carbon nanotubes, the assembly of graphitic impurity fragments in the tube-in-tube structures hinders lithium-ion diffusion, thus drastically decreasing the rate performance of lithium-ion storage. Significantly, our results indicate that the lithium-ion storage capacity of carbon nanotubes as anode electrodes can be improved or controlled by optimizing the microstructure composition of impurity graphitic nanoparticles or graphene fragments in the matrix of the carbon nanotubes.

  4. Investigating the Role of Carbonate Ion Concentration on the Magnesium Content of Amorphous Calcium Carbonate

    NASA Astrophysics Data System (ADS)

    Blue, C.; Dove, P. M.; Han, N.

    2011-12-01

    The fields of biomineralization and carbonate geochemistry are undergoing a paradigm shift with the realization that the formation of calcite with diverse compositions and textures can be understood within the framework of multiple pathways to mineralization. Many organisms do not form their skeletons via the classical step-growth process, but instead mineralization occurs through a mesocrystal pathway that begins with the formation of amorphous calcium carbonate (ACC), which subsequently transforms to calcite. Little is known about factors that regulate this type of calcification because the last 50 years of research have focused almost entirely on step-growth processes. In particular, new findings indicate that the chemical signatures and properties of calcites that form via an amorphous pathway are significantly different. Variable temperature has been shown to influence the amount of magnesium that is incorporated into ACC, but the effect of alkalinity has not been constrained. Here, a flow-through method was developed to produce ACC within a geochemically relevant pH range and with a constant supersaturation, and to determine the effect of carbonate ion concentration on magnesium uptake. The experimental approach uses a high precision syringe pump to prepare ACC under specified and constant chemical conditions. This study used two syringes that contained: 1) 100 ml of MgCl2?6H2O and CaCl2?2H2O such that the Mg/Ca ratio is fixed at 5:1 (modern seawater), and 2) 100 ml of 60mM - 400mM NaHCO3. The initial sodium bicarbonate solutions were buffered to a pH of 9.75 using NaOH, and upon mixing with the 5:1 Mg/Ca solution the resulting pH range was 9.2 - 9.7. All experiments were performed at temperatures between 21.5 and 23 degrees Celsius. Solution and solids were collected on 0.20 micron filter paper with a vacuum pump running continuously. Experiments were typically conducted for an hour and a half and all samples were rinsed with distilled deionized water before

  5. The Properties and Characteristics of Concretes Containing Calcium Carbonate (CaCO3) and Synthetic Lightweight Aggregate

    NASA Astrophysics Data System (ADS)

    Ramos, Matthew J.

    The purpose of this study was to investigate the efficacy of precipitated calcium carbonate as a means for enhancing the mechanical and environmental favorability of concretes containing synthetic lightweight aggregates (SLA), which are comprised of recycled mixed plastic and fly ash. Compressive strength tests show that 2% calcium carbonate additions are able to mitigate strength decreases induced by SLA as well as decrease concrete density when compared to NWA concretes. SLA concretes containing 5% calcium carbonate do not show the same trend. Instead, strength decreases and density increases are observed. Furthermore, increases in aluminum trisulphate (AFt) phase mineralization are observed through scanning electron microscopy. Results suggest that calcium carbonate additions increase early hydration and stabilize AFt minerals thaumasite and ettringite throughout hydration. It is proposed that increased AFt phase mineralization causes reductions in concrete density. However, a limit to this relationship was observed as additions of greater than 2% calcium carbonate exceed the potential for increased hydration, causing a threshold effect that resulted in calcium carbonate acting as filler, which increases density. Improved mechanical properties and the ability to stabilize waste plastics, fly ash, and CO2 emissions make the use of 2% calcium carbonate in conjunction with SLA a favorable alternative to ordinary concretes.

  6. Comparative study on in vivo response of porous calcium carbonate composite ceramic and biphasic calcium phosphate ceramic.

    PubMed

    He, Fupo; Ren, Weiwei; Tian, Xiumei; Liu, Wei; Wu, Shanghua; Chen, Xiaoming

    2016-07-01

    In a previous study, robust calcium carbonate composite ceramics (CC/PG) were prepared by using phosphate-based glass (PG) as an additive, which showed good cell response. In the present study the in vivo response of porous CC/PG was compared to that of porous biphasic calcium phosphate ceramics (BCP), using a rabbit femoral critical-size grafting model. The materials degradation and bone formation processes were evaluated by general observation, X-ray radiography, micro-computed tomography, and histological examination. The results demonstrated excellent biocompatibility and osteoconductivity, and progressive degradation of CC/PG and BCP. Although the in vitro degradation rate of CC/PG was distinctly faster than that of BCP, at 4week post-implantation, the bone generation and material degradation of CC/PG were less than those of BCP. Nevertheless, at postoperative week 8, the increment of bone formation and material degradation of CC/PG was pronouncedly larger than that of BCP. These results show that CC/PG is a potential resorbable bone graft aside from the traditional synthetic ones.

  7. Comparative study on in vivo response of porous calcium carbonate composite ceramic and biphasic calcium phosphate ceramic.

    PubMed

    He, Fupo; Ren, Weiwei; Tian, Xiumei; Liu, Wei; Wu, Shanghua; Chen, Xiaoming

    2016-07-01

    In a previous study, robust calcium carbonate composite ceramics (CC/PG) were prepared by using phosphate-based glass (PG) as an additive, which showed good cell response. In the present study the in vivo response of porous CC/PG was compared to that of porous biphasic calcium phosphate ceramics (BCP), using a rabbit femoral critical-size grafting model. The materials degradation and bone formation processes were evaluated by general observation, X-ray radiography, micro-computed tomography, and histological examination. The results demonstrated excellent biocompatibility and osteoconductivity, and progressive degradation of CC/PG and BCP. Although the in vitro degradation rate of CC/PG was distinctly faster than that of BCP, at 4week post-implantation, the bone generation and material degradation of CC/PG were less than those of BCP. Nevertheless, at postoperative week 8, the increment of bone formation and material degradation of CC/PG was pronouncedly larger than that of BCP. These results show that CC/PG is a potential resorbable bone graft aside from the traditional synthetic ones. PMID:27127035

  8. The mineral phase in the cuticles of two species of Crustacea consists of magnesium calcite, amorphous calcium carbonate, and amorphous calcium phosphate.

    PubMed

    Becker, Alexander; Ziegler, Andreas; Epple, Matthias

    2005-05-21

    The cuticules (shells) of the woodlice Porcellio scaber and Armadillidium vulgare were analysed with respect to their content of inorganic material. It was found that the cuticles consist of crystalline magnesium calcite, amorphous calcium carbonate (ACC), and amorphous calcium phosphate (ACP), besides small amounts of water and an organic matrix. It is concluded that the cuticle, which constitutes a mineralized protective organ, is chemically adapted to the biological requirements by this combination of different materials. PMID:15877152

  9. Microbially-Mediated Precipitation of Calcium Carbonate Nanoparticles.

    PubMed

    Kang, Ser Ku; Roh, Yul

    2016-02-01

    The objective of this study was to investigate the biomineralization of carbonate minerals using microorganisms (Wu Do-1) enriched from rhodoliths. A 16S rRNA sequence analysis showed that Wu Do-1 mainly contained Proteus mirabilis. The pH decreased from 6.5 to 5.3 over the first 4 days of incubation due to microbial oxidation of organic acids, after which it increased to 7.8 over the remaining incubation period. XRD analysis showed that the precipitates were Mg-rich cal- cite (MgxCa(1-x)CO3), whereas no precipitates were formed without the addition of Wu Do-1 in D-1 medium. SEM-EDS analyses showed that the Mg-rich calcite had a rhombohedron shape and consisted of Ca, Si and Mg with an extracelluar polymeric substance (EPS). In addition, TEM-EDS analyses revealed they were hexagon in shape, 500-700 nm in size, and composed of Ca, Mg, C, and O. These results indicated that Wu Do-1 induced precipitation of Mg-rich calcite on the cell walls and EPS via the accumulation of Ca and/or Mg ions. Therefore, microbial precipitation of carbonate nanoparticles may play an important role in metal and carbon biogeochemistry, as well as in carbon sequestration in natural environments. PMID:27433711

  10. Microbially-Mediated Precipitation of Calcium Carbonate Nanoparticles.

    PubMed

    Kang, Ser Ku; Roh, Yul

    2016-02-01

    The objective of this study was to investigate the biomineralization of carbonate minerals using microorganisms (Wu Do-1) enriched from rhodoliths. A 16S rRNA sequence analysis showed that Wu Do-1 mainly contained Proteus mirabilis. The pH decreased from 6.5 to 5.3 over the first 4 days of incubation due to microbial oxidation of organic acids, after which it increased to 7.8 over the remaining incubation period. XRD analysis showed that the precipitates were Mg-rich cal- cite (MgxCa(1-x)CO3), whereas no precipitates were formed without the addition of Wu Do-1 in D-1 medium. SEM-EDS analyses showed that the Mg-rich calcite had a rhombohedron shape and consisted of Ca, Si and Mg with an extracelluar polymeric substance (EPS). In addition, TEM-EDS analyses revealed they were hexagon in shape, 500-700 nm in size, and composed of Ca, Mg, C, and O. These results indicated that Wu Do-1 induced precipitation of Mg-rich calcite on the cell walls and EPS via the accumulation of Ca and/or Mg ions. Therefore, microbial precipitation of carbonate nanoparticles may play an important role in metal and carbon biogeochemistry, as well as in carbon sequestration in natural environments.

  11. Precipitation of calcium carbonate in aqueous solutions in presence of ethylene glycol and dodecane.

    NASA Astrophysics Data System (ADS)

    Natsi, Panagiota D.; Rokidi, Stamatia; Koutsoukos, Petros G.

    2015-04-01

    The formation of calcium carbonate (CaCO3) in aqueous supersaturated solutions has been intensively studied over the past decades, because of its significance for a number of processes of industrial and environmental interest. In the oil and gas production industry the deposition of calcium carbonate affects adversely the productivity of the wells. Calcium carbonate scale deposits formation causes serious problems in water desalination, CO2 sequestration in subsoil wells, in geothermal systems and in heat exchangers because of the low thermal coefficient of the salt. Amelioration of the operational conditions is possible only when the mechanisms underlying nucleation and crystal growth of calcium carbonate in the aqueous fluids is clarified. Given the fact that in oil production processes water miscible and immiscible hydrocarbons are present the changes of the dielectric constant of the fluid phase has serious impact in the kinetics of calcium carbonate precipitation, which remains largely unknown. The problem becomes even more complicated if polymorphism exhibited by calcium carbonate is also taken into consideration. In the present work, the stability of aqueous solutions supersaturated with respect to all calcium carbonate polymorphs and the subsequent kinetics of calcium carbonate precipitation were measured. The measurements included aqueous solutions and solutions in the presence of water miscible (ethylene glycol, MEG) and water immiscible organics (n-dodecane). All measurements were done at conditions of sustained supersaturation using the glass/ Ag/AgCl combination electrode as a probe of the precipitation and pH as the master variable for the addition of titrant solutions with appropriate concentration needed to maintenance the solution supersaturation. Initially, the metastable zone width was determined from measurements of the effect of the solution supersaturation on the induction time preceding the onset of precipitation at free-drift conditions. The

  12. Tamarind (Tamarindus indica) fruit shell carbon: A calcium-rich promising adsorbent for fluoride removal from groundwater.

    PubMed

    Sivasankar, V; Rajkumar, S; Murugesh, S; Darchen, A

    2012-07-30

    Tamarindus indica fruit shells (TIFSs) are naturally calcium rich compounds. They were impregnated with ammonium carbonate and then carbonized, leading to ammonium carbonate activated ACA-TIFS carbon. The resulting materials and carbon arising from virgin fruit shells V-TIFS were characterized and assayed as adsorbent for the removal of fluoride anions from groundwater. The fluoride scavenging ability of TIFS carbons was due to naturally dispersed calcium compounds. X-ray diffraction (XRD) showed that TIFS carbon contained a mixture of calcium oxalate and calcium carbonate. Batch studies on the fluoride removal efficiency of TIFS carbons with respect to contact time, pH, initial fluoride concentration, and co-ion interference were conducted. Applicability of various kinetic models (viz., pseudo-first-order, pseudo-second-order, intra-particle diffusion and Elovich) and sorption isotherms were tested for batch techniques. The fluoride removal capacity of TIFS carbons was found to be 91% and 83% at a pH of 7.05 for V-TIFS and ACA-TIFS carbons, respectively. The practical applicability of TIFS carbons using groundwater samples was approved. The fluoride removal was greater in groundwater without hydrogen carbonate ions than those containing these ions. The characterizations of fluoride unloaded and loaded TIFS carbons were done by SEM and XRD studies.

  13. [Multiple calcium oxalate stone formation in a patient with glycogen storage disease type I (von Gierke's disease) and renal tubular acidosis type I: a case report].

    PubMed

    Kanematsu, A; Segawa, T; Kakehi, Y; Takeuchi, H

    1993-07-01

    A case of multiple urinary stones in a patient with glycogen storage disease type 1 (GSD-1) is reported. In spite of the presence of hyperuricemia, these stones did not consist of uric acid, but mainly of calcium oxalate. Laboratory studies revealed distal renal tubular acidosis and hypocitraturia, but no significant abnormality in calcium metabolism. We discussed the mechanism of calcium stone formation in our case, and its prophylactic treatment by oral administration of citrate compound. PMID:8362684

  14. Aggregation of carbon dioxide sequestration storage assessment units

    USGS Publications Warehouse

    Blondes, Madalyn S.; Schuenemeyer, John H.; Olea, Ricardo A.; Drew, Lawrence J.

    2013-01-01

    The U.S. Geological Survey is currently conducting a national assessment of carbon dioxide (CO2) storage resources, mandated by the Energy Independence and Security Act of 2007. Pre-emission capture and storage of CO2 in subsurface saline formations is one potential method to reduce greenhouse gas emissions and the negative impact of global climate change. Like many large-scale resource assessments, the area under investigation is split into smaller, more manageable storage assessment units (SAUs), which must be aggregated with correctly propagated uncertainty to the basin, regional, and national scales. The aggregation methodology requires two types of data: marginal probability distributions of storage resource for each SAU, and a correlation matrix obtained by expert elicitation describing interdependencies between pairs of SAUs. Dependencies arise because geologic analogs, assessment methods, and assessors often overlap. The correlation matrix is used to induce rank correlation, using a Cholesky decomposition, among the empirical marginal distributions representing individually assessed SAUs. This manuscript presents a probabilistic aggregation method tailored to the correlations and dependencies inherent to a CO2 storage assessment. Aggregation results must be presented at the basin, regional, and national scales. A single stage approach, in which one large correlation matrix is defined and subsets are used for different scales, is compared to a multiple stage approach, in which new correlation matrices are created to aggregate intermediate results. Although the single-stage approach requires determination of significantly more correlation coefficients, it captures geologic dependencies among similar units in different basins and it is less sensitive to fluctuations in low correlation coefficients than the multiple stage approach. Thus, subsets of one single-stage correlation matrix are used to aggregate to basin, regional, and national scales.

  15. Ocean acidification accelerates net calcium carbonate loss in a coral rubble community

    NASA Astrophysics Data System (ADS)

    Stubler, Amber D.; Peterson, Bradley J.

    2016-09-01

    Coral rubble communities are an important yet often overlooked component of a healthy reef ecosystem. The organisms inhabiting reef rubble are primarily bioeroders that contribute to the breakdown and dissolution of carbonate material. While the effects of ocean acidification on calcifying communities have been well studied, there are few studies investigating the response of bioeroding communities to future changes in pH and calcium carbonate saturation state. Using a flow-through pH-stat system, coral rubble pieces with a naturally occurring suite of organisms, along with bleached control rubble pieces, were subjected to three different levels of acidification over an 8-week period. Rates of net carbonate loss in bleached control rubble doubled in the acidification treatments (0.02 vs. 0.04% CaCO3 d-1 in ambient vs. moderate and high acidification), and living rubble communities experienced significantly increased rates of net carbonate loss from ambient to high acidification conditions (0.06 vs. 0.10% CaCO3 d-1, respectively). Although more experimentation is necessary to understand the long-term response and succession of coral rubble communities under projected conditions, these results suggest that rates of carbonate loss will increase in coral rubble as pH and calcium carbonate saturation states are reduced. This study demonstrates a need to thoroughly investigate the contribution of coral rubble to the overall carbonate budget, reef resilience, recovery, and function under future conditions.

  16. Storage of Hydrogen in Single-Walled Carbon Nanotubes

    SciTech Connect

    Dillon, A. C.; Jones, K. M.; Bekkedahl, T. A.; Kiang, C. H.; Bethune, D. S.; Heben, M. J.

    1997-03-27

    Pores of molecular dimensions can adsorb large quantities of gases owing to the enhanced density of the adsorbed material inside the pores, a consequence of the attractive potential of the pore walls. Pederson and Broughton have suggested that carbon nanotubes, which have diameters of typically a few nanometres, should be able to draw up liquids by capillarity, and this effect has been seen for low-surface-tension liquids in large-diameter, multi-walled nanotubes. Here we show that a gas can condense to high density inside narrow, single-walled nanotubes (SWNTs). Temperature-programmed desorption spectroscopy shows that hydrogen will condense inside SWNTs under conditions that do not induce adsorption within a standard mesoporous activated carbon. The very high hydrogen uptake in these materials suggests that they might be effective as a hydrogen-storage material for fuel-cell electric vehicles.

  17. Environmental Responses to Carbon Mitigation through Geological Storage

    SciTech Connect

    Cunningham, Alfred; Bromenshenk, Jerry

    2013-08-30

    In summary, this DOE EPSCoR project is contributing to the study of carbon mitigation through geological storage. Both deep and shallow subsurface research needs are being addressed through research directed at improved understanding of environmental responses associated with large scale injection of CO{sub 2} into geologic formations. The research plan has two interrelated research objectives. Objective 1: Determine the influence of CO{sub 2}-related injection of fluids on pore structure, material properties, and microbial activity in rock cores from potential geological carbon sequestration sites. Objective 2: Determine the Effects of CO{sub 2} leakage on shallow subsurface ecosystems (microbial and plant) using field experiments from an outdoor field testing facility.

  18. Lignin Based Carbon Materials for Energy Storage Applications

    SciTech Connect

    Chatterjee, Sabornie; Saito, Tomonori; Rios, Orlando; Johs, Alexander

    2014-01-01

    The implementation of Li-ion battery technology into electric and hybrid electric vehicles and portable electronic devices such as smart phones, laptops and tablets, creates a demand for efficient, economic and sustainable materials for energy storage. However, the high cost and long processing time associated with manufacturing battery-grade anode and cathode materials are two big constraints for lowering the total cost of batteries and environmentally friendly electric vehicles. Lignin, a byproduct of the pulp and paper industry and biorefinery, is one of the most abundant and inexpensive natural biopolymers. It can be efficiently converted to low cost carbon fibers with optimal properties for use as anode materials. Recent developments in the preparation of lignin precursors and conversion to carbon fiber-based anode materials have created a new class of anode materials with excellent electrochemical characteristics suitable for immediate use in existing Li- or Na-ion battery technologies.

  19. Ecosystem and Societal Consequences of Ocean versus Atmosphere Carbon Storage

    NASA Astrophysics Data System (ADS)

    Barry, J. P.; Adams, E. E.; Bleck, R.; Caldeira, K.; Carman, K.; Erickson, D.; Kennett, J. P.; Sarmiento, J. L.; Tsouris, C.

    2005-12-01

    Climate stabilization during the next 100 to 200 y will require significant reductions in atmospheric carbon dioxide emissions to avoid large increases in global temperature. While there is only mild disagreement concerning carbon management options such as energy efficiency, alternative energy sources, and even geologic C storage, ocean storage remains controversial, due to its potential impacts for deep-sea ecosystems. A cautionary approach to carbon management might avoid any ocean C storage. However, this approach does not consider the balance between ocean and terrestrial ecosystems, or societal concerns. Using a broader perspective, we might ask whether atmospheric CO2 storage (i.e. the status quo), or deep ocean sequestration is better for Earth's ecosystems and societies? We explored the potential storage capacity of the deep ocean for carbon dioxide, under scenarios producing a 0.2 pH unit reduction, a level similar to observed scale of pH variability in deep ocean basins, which may also represent coarse thresholds for deep-sea ecosystem impacts. Roughly 500 PgC could be stored in the deep ocean to lower pH by 0.2 units, yielding a long term (~250 y) ocean sequestration program of 2 PgCy-1. The mitigation value of such ocean C sequestration for upper ocean and terrestrial systems depends strongly on future emission scenarios. Under a low emission scenario (e.g. SRES scenario A1T, B1; atm CO2 ~575 ppm, global temperature change of ~+2 oC), a 2 PgCy-1 ocean CO2 injection program could mitigate global temperature by ~-0.4 oC (20%) by 2100. This could reduce significantly the number of people at risk of water shortage and tropical diseases, with lesser improvement expected for hunger or coastal flooding. Mitigation for terrestrial and shallow ocean ecosystems is difficult to predict. A 0.4 oC reduction in warming this century is expected to delay the progression of coral reef devastation by roughly 20 y. The mitigation potential of ocean storage under very

  20. EFFECTS OF SODIUM AND CALCIUM IN LIGNITE ON THE PERFORMANCE OF ACTIVATED CARBON PRODUCTS

    SciTech Connect

    Edwin S. Olson; Kurt E. Eylands; Daniel J. Stepan

    2001-12-01

    Powdered activated carbon (PAC) has traditionally been used by the water treatment industry for the removal of compounds contributing to taste and odor problems. PAC also has the potential to remove naturally occurring organic matter (NOM) from raw waters prior to disinfection, thus controlling the formation of regulated disinfection by-products (DBPs). Many small water systems are currently using PAC for taste and odor control and have the potential to use PAC for controlling DBPs. The Energy & Environmental Research Center has been working on the development of a PAC product to remove NOM from surface water supplies to prevent the formation of carcinogenic DBPs during chlorination. During previous studies, the sodium and calcium content of the lignites showed a significant effect on the sorption capacity of the activated carbon product. As much as a 130% increase in the humic acid sorption capacity of a PAC produced from a high-sodium-content lignite was observed. During this study, activated carbons were prepared from three coals representing high-sodium, low-sodium--low-calcium, and high-calcium compositions in two steps, an initial char formation followed by mild activation with steam to avoid excessive burnout. This set of carbons was characterized with respect to physical and chemical properties. The BET (Brunauer-Emmett-Teller) nitrogen adsorption isotherms gave relatively low surface areas (ranging from 245 to 370 m{sup 2}/g). The lowest-BET area was obtained for the high-sodium carbon, which can be attributed to enlargement of micropores as a result of sodium-catalyzed gasification reaction of the carbon structure. This hypothesis is consistent with the scanning electron microscopy microprobe analyses, which show that in both the coal and the activated carbon from this coal, the sodium is distributed over both the carbon structure and the mineral particles. Thus it is initially associated with carboxylate groups on the coal and then as sodium oxide or

  1. A review: Different methods producing different particles size and distribution in synthesis of calcium carbonate nano particles

    NASA Astrophysics Data System (ADS)

    Sulimai, N. H.; Rusop, M.; Alrokayan, Salman A. H.; Khan, Haseeb A.

    2016-07-01

    Carbonates exist as 73 percent of world crust carbon. Abundance and bioavailability of Calcium Carbonates offer reliable resources, costs saving and environmental friendly potentials in its applications. Studies proven nano-sized Calcium Cabonate (nCC) employs a more significant characteristics compared to larger sizes. Properties of nCC is affected by the dispersion of the particles in which agglomeration occurs. It is important to gain more understanding of the conditions contributing or stunting the agglomeration to gain more control of the particles morphology and dynamic. A few recent studies with different methods to prepare calcium carbonate nanoparticles were listed in Table 1 .Particle size and dispersity of calcium carbonate are affected by different conditions of its preparation. Other factors such as mechanical aggression, concentration of solution, temperature of precipitation, pH of reaction are all contributing factors towards particle sizes and distribution.

  2. A geospatial assessment of the relationship between reef flat community calcium carbonate production and wave energy

    NASA Astrophysics Data System (ADS)

    Hamylton, S. M.; Pescud, A.; Leon, J. X.; Callaghan, D. P.

    2013-12-01

    The ability of benthic communities inhabiting coral reefs to produce calcium carbonate underpins the development of reef platforms and associated sedimentary landforms, as well as the fixation of inorganic carbon and buffering of diurnal pH fluctuations in ocean surface waters. Quantification of the relationship between reef flat community calcium carbonate production and wave energy provides an empirical basis for understanding and managing this functionally important process. This study employs geospatial techniques across the reef platform at Lizard Island, Great Barrier Reef, to (1) map the distribution and estimate the total magnitude of reef community carbonate production and (2) empirically ascertain the influence of wave energy on community carbonate production. A World-View-2 satellite image and a field data set of 364 ground referencing points are employed, along with data on physical reef characteristics (e.g. bathymetry, rugosity) to map and validate the spatial distribution of the four major community carbonate producers (live coral, carbonate sand, green calcareous macroalgae and encrusting calcified algae) across the reef platform. Carbonate production is estimated for the complete reef platform from the composition of these community components. A synoptic model of wave energy is developed using the Simulating WAves Nearshore (SWAN) two-dimensional model for the entire reef platform. The relationship between locally derived measures of carbonate production and wave energy is evaluated at both the global scale and local scale along spatial gradients of wave energy traversing the reef platform. A wave energy threshold is identified, below which carbonate production levels appear to increase with wave energy and above which mechanical forcing reduces community production. This implies an optimal set of hydrodynamic conditions characterized by wave energy levels of approximately 300 J m-2, providing an empirical basis for management of potential changes

  3. Geophysical monitoring and reactive transport modeling of ureolytically-driven calcium carbonate precipitation.

    PubMed

    Wu, Yuxin; Ajo-Franklin, Jonathan B; Spycher, Nicolas; Hubbard, Susan S; Zhang, Guoxiang; Williams, Kenneth H; Taylor, Joanna; Fujita, Yoshiko; Smith, Robert

    2011-09-23

    Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH4

  4. Geophysical monitoring and reactive transport modeling of ureolytically-driven calcium carbonate precipitation

    PubMed Central

    2011-01-01

    Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH4

  5. Geophysical Monitoring and Reactive Transport Modeling of Ureolytically-Driven Calcium Carbonate Precipitation

    SciTech Connect

    Yuxin Wu; Jonathan B. Ajo-Franklin; Nicolas Spycher; Susan S. Hubbard; Guoxiang Zhang; Kenneth H. Williams; Joanna Taylor; Yoshiko Fujita; Robert Smith

    2011-09-01

    Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH4

  6. Geophysical monitoring and reactive transport modeling of ureolytically-driven calcium carbonate precipitation

    SciTech Connect

    Wu, Y.; Ajo-Franklin, J.B.; Spycher, N.; Hubbard, S.S.; Zhang, G.; Williams, K.H.; Taylor, J.; Fujita, Y.; Smith, R.

    2011-07-15

    Ureolytically-driven calcium carbonate precipitation is the basis for a promising in-situ remediation method for sequestration of divalent radionuclide and trace metal ions. It has also been proposed for use in geotechnical engineering for soil strengthening applications. Monitoring the occurrence, spatial distribution, and temporal evolution of calcium carbonate precipitation in the subsurface is critical for evaluating the performance of this technology and for developing the predictive models needed for engineering application. In this study, we conducted laboratory column experiments using natural sediment and groundwater to evaluate the utility of geophysical (complex resistivity and seismic) sensing methods, dynamic synchrotron x-ray computed tomography (micro-CT), and reactive transport modeling for tracking ureolytically-driven calcium carbonate precipitation processes under site relevant conditions. Reactive transport modeling with TOUGHREACT successfully simulated the changes of the major chemical components during urea hydrolysis. Even at the relatively low level of urea hydrolysis observed in the experiments, the simulations predicted an enhanced calcium carbonate precipitation rate that was 3-4 times greater than the baseline level. Reactive transport modeling results, geophysical monitoring data and micro-CT imaging correlated well with reaction processes validated by geochemical data. In particular, increases in ionic strength of the pore fluid during urea hydrolysis predicted by geochemical modeling were successfully captured by electrical conductivity measurements and confirmed by geochemical data. The low level of urea hydrolysis and calcium carbonate precipitation suggested by the model and geochemical data was corroborated by minor changes in seismic P-wave velocity measurements and micro-CT imaging; the latter provided direct evidence of sparsely distributed calcium carbonate precipitation. Ion exchange processes promoted through NH{sub 4}{sup

  7. Construction of two ureolytic model organisms for the study of microbially induced calcium carbonate precipitation.

    PubMed

    Connolly, James; Kaufman, Megan; Rothman, Adam; Gupta, Rashmi; Redden, George; Schuster, Martin; Colwell, Frederick; Gerlach, Robin

    2013-09-01

    Two bacterial strains, Pseudomonas aeruginosa MJK1 and Escherichia coli MJK2, were constructed that both express green fluorescent protein (GFP) and carry out ureolysis. These two novel model organisms are useful for studying bacterial carbonate mineral precipitation processes and specifically ureolysis-driven microbially induced calcium carbonate precipitation (MICP). The strains were constructed by adding plasmid-borne urease genes (ureABC, ureD and ureFG) to the strains P. aeruginosa AH298 and E. coli AF504gfp, both of which already carried unstable GFP derivatives. The ureolytic activities of the two new strains were compared to the common, non-GFP expressing, model organism Sporosarcina pasteurii in planktonic culture under standard laboratory growth conditions. It was found that the engineered strains exhibited a lower ureolysis rate per cell but were able to grow faster and to a higher population density under the conditions of this study. Both engineered strains were successfully grown as biofilms in capillary flow cell reactors and ureolysis-induced calcium carbonate mineral precipitation was observed microscopically. The undisturbed spatiotemporal distribution of biomass and calcium carbonate minerals were successfully resolved in 3D using confocal laser scanning microscopy. Observations of this nature were not possible previously because no obligate urease producer that expresses GFP had been available. Future observations using these organisms will allow researchers to further improve engineered application of MICP as well as study natural mineralization processes in model systems.

  8. Amorphous calcium carbonate precipitation by cellular biomineralization in mantle cell cultures of Pinctada fucata.

    PubMed

    Xiang, Liang; Kong, Wei; Su, Jing-Tan; Su, Jingtan; Liang, Jian; Zhang, Gui-You; Zhang, Guiyou; Xie, Li-Ping; Xie, Liping; Zhang, Rong-Qing; Zhang, Rongqing

    2014-01-01

    The growth of molluscan shell crystals is generally thought to be initiated from the extrapallial fluid by matrix proteins, however, the cellular mechanisms of shell formation pathway remain unknown. Here, we first report amorphous calcium carbonate (ACC) precipitation by cellular biomineralization in primary mantle cell cultures of Pinctada fucata. Through real-time PCR and western blot analyses, we demonstrate that mantle cells retain the ability to synthesize and secrete ACCBP, Pif80 and nacrein in vitro. In addition, the cells also maintained high levels of alkaline phosphatase and carbonic anhydrase activity, enzymes responsible for shell formation. On the basis of polarized light microscopy and scanning electron microscopy, we observed intracellular crystals production by mantle cells in vitro. Fourier transform infrared spectroscopy and X-ray diffraction analyses revealed the crystals to be ACC, and de novo biomineralization was confirmed by following the incorporation of Sr into calcium carbonate. Our results demonstrate the ability of mantle cells to perform fundamental biomineralization processes via amorphous calcium carbonate, and these cells may be directly involved in pearl oyster shell formation.

  9. Amorphous Calcium Carbonate Precipitation by Cellular Biomineralization in Mantle Cell Cultures of Pinctada fucata

    PubMed Central

    Xiang, Liang; Kong, Wei; Su, Jingtan; Liang, Jian; Zhang, Guiyou; Xie, Liping; Zhang, Rongqing

    2014-01-01

    The growth of molluscan shell crystals is generally thought to be initiated from the extrapallial fluid by matrix proteins, however, the cellular mechanisms of shell formation pathway remain unknown. Here, we first report amorphous calcium carbonate (ACC) precipitation by cellular biomineralization in primary mantle cell cultures of Pinctada fucata. Through real-time PCR and western blot analyses, we demonstrate that mantle cells retain the ability to synthesize and secrete ACCBP, Pif80 and nacrein in vitro. In addition, the cells also maintained high levels of alkaline phosphatase and carbonic anhydrase activity, enzymes responsible for shell formation. On the basis of polarized light microscopy and scanning electron microscopy, we observed intracellular crystals production by mantle cells in vitro. Fourier transform infrared spectroscopy and X-ray diffraction analyses revealed the crystals to be ACC, and de novo biomineralization was confirmed by following the incorporation of Sr into calcium carbonate. Our results demonstrate the ability of mantle cells to perform fundamental biomineralization processes via amorphous calcium carbonate, and these cells may be directly involved in pearl oyster shell formation. PMID:25405357

  10. Carbon storage in Swedish bedrock - current status regarding potential storage areas and geophysical information

    NASA Astrophysics Data System (ADS)

    Bergman, B.; Juhojuntti, N. G.

    2010-12-01

    Carbon Capture and Storage (CCS) is increasingly considered as an option to reduce the release of CO2 to the atmosphere. There is today a significant interest from Swedish heavy industry in CCS-technology. Large point sources are found within process industry related to e.g. production of paper and steel (operating under European Union regulations). There is also significant emission of CO2 from burning of biomass for energy production. However, this process is considered to be climate neutral and thus the emissions are not included in the carbon trading schemes. Based on recent work at the Geological Survey of Sweden and by other organizations we discuss the possibilities for geological storage of CO2 in Sweden, including the locations of the potential storage sites and the main CO2 emitters. In this context, we also review the relevant geophysical data available at the Geological Survey, focusing on the seismic data but also including gravity and magnetic data. Deep saline aquifers are presently considered as the most realistic storage alternative in Sweden. Sedimentary bedrock containing such layers and which could be suitable for CO2 storage is mainly found within the southern Baltic Sea and around southernmost Sweden, close to Denmark. The knowledge about the sedimentary bedrock in these areas is mainly based on seismic measurements and drilling in connection with hydrocarbon prospecting during the 70’s and the 80’s. Approximately 40.000 km’s of seismic reflection profiles were acquired, mostly in the potential CO2 storage areas mentioned above. Data from these profiles are now archived at the Geological Survey, and currently the magnetic tapes (8000-9000 reels) are being transcribed to modern storage media, a work that will likely be finished during 2011. Despite the hydrocarbon prospecting in these areas there are remaining uncertainties regarding the suitability of the sedimentary bedrock for CO2 storage, in particular related to the porosity and

  11. Carbonation as a binding mechanism for coal/calcium hydroxide pellets. [Quarterly] technical report, March 1, 1993--May 31, 1993

    SciTech Connect

    Lytle, J.; Hackley, K.; Dagamac, M.; Berger, R.; Schanche, G.

    1993-09-01

    This research is an investigation of calcium hydroxide, a sulfur-capturing sorbent, as a binder for coal fines. The reaction of carbon dioxide with calcium hydroxide, referred to as carbonation, is being studied as a method of improving pellet quality. Carbonation forms a cementitious matrix of calcium carbonate. The effect of particle size and compaction pressure on pellet strength was studied using a laboratory hydraulic press. Particle distributions with mean sizes of 200, 90 and 40 microns were tested. The results indicate that pellet strength increased with decreasing particle size and increasing compaction pressure when calcium hydroxide was used as a binder. Pellets containing 10 wt% calcium hydroxide increased in strength by approximately 40% when air dried for one day. This increase in strength is attributed to carbonation of the calcium hydroxide via atmospheric carbon dioxide. Corn starch, an adhesive binder, was tested at the finest particle size. Pellet strength did not increase as a function of increasing compaction pressure. At the finest particle size and highest compaction pressure (18,750 psi), dried pellets formed with 2 wt% corn starch were equivalent in strength to pellets containing 5 wt% calcium hydroxide.

  12. Impact of bioenergy production on carbon storage and soil functions

    NASA Astrophysics Data System (ADS)

    Prays, Nadia; Franko, Uwe

    2016-04-01

    An important renewable energy source is methane produced in biogas plants (BGPs) that convert plant material and animal excrements to biogas and a residue (BGR). If the plant material stems from crops produced specifically for that purpose, a BGP have a 'footprint' that is defined by the area of arable land needed for the production of these energy crops and the area for distributing the BGRs. The BGR can be used to fertilize these lands (reducing the need for carbon and nitrogen fertilizers), and the crop land can be managed to serve as a carbon sink, capturing atmospheric CO2. We focus on the ecological impact of different BGPs in Central Germany, with a specific interest in the long-term effect of BGR-fertilization on carbon storage within the footprint of a BGP. We therefore studied nutrient fluxes using the CANDY (CArbon and Nitrogen Dynamics) model, which processes site-specific information on soils, crops, weather, and land management to compute stocks and fluxes of carbon and nitrogen for agricultural fields. We used CANDY to calculated matter fluxes within the footprints of BGPs of different sizes, and studied the effect of the substrate mix for the BGP on the carbon dynamics of the soil. This included the land requirement of the BGR recycling when used as a fertilizer: the footprint of a BGP required for the production of the energy crop generally differs from its footprint required to take up its BGR. We demonstrate how these findings can be used to find optimal cropping choices and land management for sustainable soil use, maintaining soil fertility and other soil functions. Furthermore, site specific potentials and limitations for agricultural biogas production can be identified and applied in land-use planning.

  13. Hierarchical cellulose-derived carbon nanocomposites for electrostatic energy storage

    NASA Astrophysics Data System (ADS)

    Kuzmenko, V.; Saleem, A. M.; Bhaskar, A.; Staaf, H.; Desmaris, V.; Enoksson, P.

    2015-12-01

    The problem of energy storage and its continuous delivery on demand needs new effective solutions. Supercapacitors are viewed as essential devices for solving this problem since they can quickly provide high power basically countless number of times. The performance of supercapacitors is mostly dependent on the properties of electrode materials used for electrostatic charge accumulation, i.e. energy storage. This study presents new sustainable cellulose-derived materials that can be used as electrodes for supercapacitors. Nanofibrous carbon nanofiber (CNF) mats were covered with vapor-grown carbon nanotubes (CNTs) in order to get composite CNF/CNT electrode material. The resulting composite material had significantly higher surface area and was much more conductive than pure CNF material. The performance of the CNF/CNT electrodes was evaluated by various analysis methods such as cyclic voltammetry, galvanostatic charge-discharge, electrochemical impedance spectroscopy and cyclic stability. The results showed that the cellulose-derived composite electrodes have fairly high values of specific capacitance and power density and can retain excellent performance over at least 2 000 cycles. Therefore it can be stated that sustainable cellulose-derived CNF/CNT composites are prospective materials for supercapacitor electrodes.

  14. Viability of Carbon Dioxide Storage in Deep Sea Sediment

    NASA Astrophysics Data System (ADS)

    Bielicki, J. M.

    2007-12-01

    Despite the public's general aversion to using the ocean to dispose of captured carbon dioxide (CO2), recent revisions of the London Protocol have removed a hurdle to subsea injection of CO2. This paper constructs a map of the worldwide "prospectivity" of CO2 storage in deep sea sediment, i.e. amenable locations are determined and storage capacities estimated. CO2 injected into deep sea sediment is expected to be gravitationally trapped and secondarily capped by CO2 hydrate formation. Capture, transport, and storage costs are estimated and a mixed-integer linear programming model that generates spatially optimized infrastructure networks is applied. The model captures CO2 from fixed point sources, uses minimum cost routing paths, aggregates CO2 flow into trunk distribution pipelines where appropriate, and injects the CO2 in potential deep sea injection sites. Economies of scale for this climate change mitigation intervention in the United States Exclusive Economic Zone are discussed, including provisions for destabilizing and/or harvesting methane from in situ gas hydrates.

  15. Hydrogen storage reactions on titanium decorated carbon nanocones theoretical study

    NASA Astrophysics Data System (ADS)

    Shalabi, A. S.; Taha, H. O.; Soliman, K. A.; Abeld Aal, S.

    2014-12-01

    Hydrogen storage reactions on Ti decorated carbon nanocones (CNC) are investigated by using the state of the art density functional theory calculations. The single Ti atom prefers to bind at the bridge site between two hexagonal rings, and can bind up to 6 hydrogen molecules with average adsorption energies of -1.73, -0.74, -0.57, -0.45, -0.42, and -0.35 eV per hydrogen molecule. No evidence for metal clustering in the ideal circumstances, and the hydrogen storage capacity is expected to be as large as 14.34 wt%. Two types of interactions are recognized. While the interaction of 2H2 with Ti-CNC is irreversible at 532 K, the interaction of 3H2 with Ti-CNC is reversible at 392 K. Further characterizations of the former two reactions are considered in terms of projected densities of states, simulated infrared and proton magnetic resonance spectra, electrophilicity, and statistical thermodynamic stability. The free energy of the highest hydrogen storage capacity reaction between 6H2 and Ti-CNC meets the ultimate targets of department of energy at (233.15 K) and (11.843 atm) with surface coverage (0.941) and (direct/inverse) rate constants ratio (1.35).

  16. Carbon Nanomaterials for Energy Storage, Actuators and Environmental Applications

    NASA Astrophysics Data System (ADS)

    Wang, Chengwei

    Carbon nanomaterials have caught tremendous attention in the last few decades due to their unique physical and chemical properties. Tremendous effort has been made to develop new synthesis techniques for carbon nanomaterials and investigate their properties for different applications. In this work, carbon nanospheres (CNSs), carbon foams (CF), and single-walled carbon nanotubes (SWNTs) were studied for various applications, including water treatment, energy storage, actuators, and sensors. A facile spray pyrolysis synthesis technique was developed to synthesize individual CNSs with specific surface area (SSA) up to 1106 m2/g. The hollow CNSs showed adsorption of up to 300 mg rhodamine B dye per gram carbon, which is more than 15 times higher than that observed for conventional carbon black. They were also evaluated as adsorbents for removal of arsenate and selenate from water and displayed good binding to both species, outperforming commercial activated carbons for arsenate removal in pH > 8. When evaluated as supercapacitor electrode materials, specific capacitances of up to 112 F/g at a current density of 0.1 A/g were observed. When used as Li-ion battery anode materials, the CNSs achieved a discharge capacity of 270 mAh/g at a current density of 372 mA/g (1C), which is 4-fold higher than that of commercial graphite anode. Carbon foams were synthesized using direct pyrolysis and had SSA up to 2340 m2/g. When used as supercapacitor electrode materials, a specific capacitance up to 280 F/g was achieved at current density of 0.1 A/g and remained as high as 207 F/g, even at a high current density of 10 A/g. A printed walking robot was made from common plastic films and coatings of SWNTs. The solid-state thermal bimorph actuators were multifunctional energy transducers powered by heat, light, or electricity. The actuators were also investigated for photo/thermal detection. Electrochemical actuators based on MnO2 were also studied for potential underwater applications

  17. X-ray Absorption Spectroscopy Identifies Calcium-Uranyl-Carbonate Complexes at Environmental Concentrations

    SciTech Connect

    Kelly, Shelly D; Kemner, Kenneth M; Brooks, Scott C

    2007-01-01

    Current research on bioremediation of uranium-contaminated groundwater focuses on supplying indigenous metal-reducing bacteria with the appropriate metabolic requirements to induce microbiological reduction of soluble uranium(VI) to poorly soluble uranium(IV). Recent studies of uranium(VI) bioreduction in the presence of environmentally relevant levels of calcium revealed limited and slowed uranium(VI) reduction and the formation of a Ca-UO2-CO3 complex. However, the stoichiometry of the complex is poorly defined and may be complicated by the presence of a Na-UO2-CO3 complex. Such a complex might exist even at high calcium concentrations, as some UO2-CO3 complexes will still be present. The number of calcium and/or sodium atoms coordinated to a uranyl carbonate complex will determine the net charge of the complex. Such a change in aqueous speciation of uranium(VI) in calcareous groundwater may affect the fate and transport properties of uranium. In this paper, we present the results from X-ray absorption fine structure (XAFS) measurements of a series of solutions containing 50 lM uranium(VI) and 30 mM sodium bicarbonate, with various calcium concentrations of 0-5 mM. Use of the data series reduces the uncertainty in the number of calcium atoms bound to the UO2-CO3 complex to approximately 0.6 and enables spectroscopic identification of the Na-UO2-CO3 complex. At nearly neutral pH values, the numbers of sodium and calcium atoms bound to the uranyl triscarbonate species are found to depend on the calcium concentration, as predicted by speciation calculations.

  18. X-ray absorption spectroscopy identifies calcium-uranyl-carbonate complexes at environmental concentrations.

    SciTech Connect

    Kelly, S. D.; Kemner, K. M.; Brooks, S. C.; Biosciences Division; ORNL

    2007-01-01

    Current research on bioremediation of uranium-contaminated groundwater focuses on supplying indigenous metal-reducing bacteria with the appropriate metabolic requirements to induce microbiological reduction of soluble uranium(VI) to poorly soluble uranium(IV). Recent studies of uranium(VI) bioreduction in the presence of environmentally relevant levels of calcium revealed limited and slowed uranium(VI) reduction and the formation of a Ca-UO{sub 2}-CO{sub 3} complex. However, the stoichiometry of the complex is poorly defined and may be complicated by the presence of a Na-UO{sub 2}-CO{sub 3} complex. Such a complex might exist even at high calcium concentrations, as some UO{sub 2}-CO{sub 3} complexes will still be present. The number of calcium and/or sodium atoms coordinated to a uranyl carbonate complex will determine the net charge of the complex. Such a change in aqueous speciation of uranium(VI) in calcareous groundwater may affect the fate and transport properties of uranium. In this paper, we present the results from X-ray absorption fine structure (XAFS) measurements of a series of solutions containing 50 {micro}M uranium(VI) and 30 mM sodium bicarbonate, with various calcium concentrations of 0-5 mM. Use of the data series reduces the uncertainty in the number of calcium atoms bound to the UO{sub 2}-CO{sub 3} complex to approximately 0.6 and enables spectroscopic identification of the Na-UO{sub 2}-CO{sub 3} complex. At nearly neutral pH values, the numbers of sodium and calcium atoms bound to the uranyl triscarbonate species are found to depend on the calcium concentration, as predicted by speciation calculations.

  19. Chemistry of calcium carbonate-rich shallow water sediments in the Bahamas

    SciTech Connect

    Morse, J.W.; Zullig, J.J.; Bernstein, L.D.; Millero, F.J.; Milne, P.; Mucci, A.; Choppin, G.R.

    1985-02-01

    The geochemistry of calcium carbonate-rich sediments from a variety of environments throughout the Bahamas was investigated with particular emphasis on the factors that control the pore water chemistry. Most sediments are supersaturated with respect to aragonite, the most abundant carbonate component. Experimental studies indicate that the observed in situ calcium carbonate ion activity products can often be produced as reversible metastable equilibria between the sediments and seawater. This is interpreted as being the result of interactions between the solutions and the minor high Mg-calcite component present in these sediments. Although the overlying waters are more supersaturated than the pore waters, carbonate dissolution, not precipitation, dominates in these sediments as a result of organic matter oxidation and the resulting increase in P/sub CO/sub 2//. The carbonate sediments of the Bahamas are remarkable for their purity, with the exception of special environments such as mangrove swamps and tidal flats with algal mats. Organic matter and heavy metal content is extremely low. Only minor sulfate reduction is occurring in most sediments. Phosphate is undetectable in all pore waters, probably as a result of adsorption on carbonate mineral surfaces. Other dissolved pore water components such as ammonia and DOC are much lower than typically found in shallow water fine-grained terrigeneous sediments.

  20. Extraction of iron and calcium from low rank coal by supercritical carbon dioxide with entrainers

    SciTech Connect

    Iwai, Y.; Okamoto, N.; Ohta, S.; Arai, Y.; Sakanishi, K.

    2007-03-15

    Iron and calcium were extracted from low rank coal with supercritical carbon dioxide and methanol, ethanol, acetic acid, acetyl acetone, ethanol and acetic acid, or acetyl acetone and water entrainers at 313.2 K and 15.0 MPa. The low rank coal used in this study was Berau coal from Indonesia. The addition of methanol, ethanol, or acetic acid entrainers in supercritical carbon dioxide showed very limited effect on enhancement of the recovery rates of Fe. The recovery rates of Fe from dried coal by supercritical carbon dioxide with acetyl acetone were low however, the addition of acetyl acetone with water in supercritical carbon dioxide remarkably enhanced the recovery rates of Fe. Water seems to play an important role in extracting Fe from coal with supercritical carbon dioxide and acetyl acetone. On the other hand, the extraction rates of Ca with supercritical carbon dioxide and water, methanol, ethanol, and acetyl acetone entrainers were very low. The addition of acetic acid with or without water in supercritical carbon dioxide slightly enhanced the recovery rates of Ca. The addition of acetic acid with ethanol in supercritical carbon dioxide remarkably enhanced the recovery rates of Ca. The effect of carbon dioxide flow rate and coal particle size on the recovery rates of Fe were examined. The recovery rate of Fe increased with increasing carbon dioxide flow rate and with decreasing particle size of the low rank coal.

  1. Calcifying Cyanobacteria - The potential of biomineralization for Carbon Capture and Storage

    SciTech Connect

    Jansson, Christer G; Northen, Trent

    2010-03-26

    Employment of cyanobacteria in biomineralization of carbon dioxide by calcium carbonate precipitation offers novel and self-sustaining strategies for point-source carbon capture and sequestration. Although details of this process remain to be elucidated, a carbon-concentrating mechanism, and chemical reactions in exopolysaccharide or proteinaceous surface layers are assumed to be of crucial importance. Cyanobacteria can utilize solar energy through photosynthesis to convert carbon dioxide to recalcitrant calcium carbonate. Calcium can be derived from sources such as gypsum or industrial brine. A better understanding of the biochemical and genetic mechanisms that carry out and regulate cynaobacterial biomineralization should put us in a position where we can further optimize these steps by exploiting the powerful techniques of genetic engineering, directed evolution, and biomimetics.

  2. Calcifying cyanobacteria--the potential of biomineralization for carbon capture and storage.

    PubMed

    Jansson, Christer; Northen, Trent

    2010-06-01

    Employment of cyanobacteria in biomineralization of carbon dioxide by calcium carbonate precipitation offers novel and self-sustaining strategies for point-source carbon capture and sequestration. Although details of this process remain to be elucidated, a carbon-concentrating mechanism, and chemical reactions in exopolysaccharide or proteinaceous surface layers are assumed to be of crucial importance. Cyanobacteria can utilize solar energy through photosynthesis to convert carbon dioxide to recalcitrant calcium carbonate. Calcium can be derived from sources such as gypsum or industrial brine. A better understanding of the biochemical and genetic mechanisms that carry out and regulate cynaobacterial biomineralization should put us in a position where we can further optimize these steps by exploiting the powerful techniques of genetic engineering, directed evolution, and biomimetics.

  3. [Distribution of soil organic carbon storage and carbon density in Gahai Wetland ecosystem].

    PubMed

    Ma, Wei-Wei; Wang, Hui; Huang, Rong; Li, Jun-Zhen; Li, De-Yu

    2014-03-01

    The profile distribution and accumulation characteristics of organic carbon of four typical marshes (herbaceous peat, marsh wetland, mountain wetland, subalpine meadow) were studied in Gahai Wetlands of Gannan in July 2011. The results showed that the soil bulk densities of the four typical marshes ranged from 0.22 to 1.29 g x cm(-3). The content of soil organic carbon in the herbaceous peat was higher than in other types, with its average content of organic carbon (286. 80 g x kg(-1)) being about 2.91, 4.99, 7.31 times as much as that of the marsh wetland, mountain wetland and subalpine meadow, respectively. The average organic carbon densities were in order of herbaceous peat > subalpine meadow > marsh wetland > mountain wetland, with the highest in the 0-10 cm layer. The change of organic carbon density along the soil profile was basically in accordance with the organic carbon content in the four typical marshes, but fluctuated with soil depth. There were obviously two carbon storage layers (0-10 and 20-40 cm, respectively) in the four typical marshes. The amounts of organic carbon stored in the 0-60 cm layer of the four typical marshes were 369.46, 278.83, 276.16, 292.23 t x hm(-2), respectively. The total amount of organic carbon stored in the 0-60 cm of the four typical marshes was about 9.50 x 10(6) t.

  4. [Changes of carbon storage and carbon sequestration in plantation ecosystems on purple soil].

    PubMed

    Yu, Zhanyuan; Yang, Yusheng; Chen, Guangshui

    2004-10-01

    This paper studied the carbon storages and carbon sequestration capacities of degraded plantation ecosystems in purple soil area. Using space-time replacement method, four ecological restoration treatments (I, II, III and IV) were selected on the basis of erosion intensions from high to low in Ninghua, Fujian. Treatment I was not treated with any other measures after afforestation. Treatment II adopted engineering soil and water conservation measure after afforestation. In treatment III, the engineering measure associated biological measure was taken after afforestation. As for treatment IV, enclosure was adopted to protect against anthropogenic disturbances after afforestation. We observed that the carbon sequestration potential was increased with weakening erosion degree, i.e., I < II < III < IV. The carbon storage of 4 treatments was 1.4, 8.5, 25.6 and 37.6 t x hm(-2), and the annual assimilation of CO2 was 712.87, 1458.01, 9718.10 and 11,109.56 kg x hm(-2), respectively. It was suggested that the restored forest ecosystem was one of the important carbon sinks in this area. Engineering soil and water conservation measure associated biological measure would be the main means of restoring degraded ecosystem. But presently, the reasonable strategy was to decrease human's disturbances, and hence, the enclosure for reforestation could be used to transform forest ecosystem into carbon sink.

  5. Carbonation acceleration of calcium hydroxide nanoparticles: induced by yeast fermentation

    NASA Astrophysics Data System (ADS)

    Lopez-Arce, Paula; Zornoza-Indart, Ainara

    2015-09-01

    Carbonation of Ca(OH)2 nanoparticles and consolidation of limestone are accelerated by high humidity and a yeast fermentation system that supplies a saturated atmosphere on CO2, H2O vapor and ethanol during 28 days. Nanoparticles were analyzed by X-ray diffraction and differential thermal analyses with thermogravimetry. Spectrophotometry, scanning electron microscopy analyses, and hydric and mechanical tests were also performed in stones specimens. Samples exposed to the yeast environment achieve 100 % relative CaCO3 yield, whereas at high humidity but without the yeast and under laboratory environment, relative yields of 95 % CaCO3 and 15 % CaCO3 are, respectively, reached, with white crusts and glazing left on the stone surfaces when the nanoparticles are applied at a concentration of 25 g/l. The largest increase in the drilling resistance and surface hardness values with slight increase in the capillarity absorption and desorption coefficients and with lesser stone color changes are produced at a concentration of 5 g/l, in the yeast system environment. This especially happens in stone specimens initially with bimodal pore size distributions, more amounts of pores with diameters between 0.1 and 1 µm, higher open porosity values and faster capillary coefficients. An inexpensive and reliable method based on water and yeast-sugar solution is presented to speed up carbonation of Ca(OH)2 nanoparticles used as a consolidating product to improve the mechanical properties of decayed limestone from archaeological and architectural heritage.

  6. Lithium and calcium carbides with polymeric carbon structures.

    PubMed

    Benson, Daryn; Li, Yanling; Luo, Wei; Ahuja, Rajeev; Svensson, Gunnar; Häussermann, Ulrich

    2013-06-01

    We studied the binary carbide systems Li2C2 and CaC2 at high pressure using an evolutionary and ab initio random structure search methodology for crystal structure prediction. At ambient pressure Li2C2 and CaC2 represent salt-like acetylides consisting of C2(2-) dumbbell anions. The systems develop into semimetals (P3m1-Li2C2) and metals (Cmcm-Li2C2, Cmcm-CaC2, and Immm-CaC2) with polymeric anions (chains, layers, strands) at moderate pressures (below 20 GPa). Cmcm-CaC2 is energetically closely competing with the ground state structure. Polyanionic forms of carbon stabilized by electrostatic interactions with surrounding cations add a new feature to carbon chemistry. Semimetallic P3m1-Li2C2 displays an electronic structure close to that of graphene. The π* band, however, is hybridized with Li-sp states and changed into a bonding valence band. Metallic forms are predicted to be superconductors. Calculated critical temperatures may exceed 10 K for equilibrium volume structures.

  7. Calcium carbonate mineralization mediated by in vitro cultured mantle cells from Pinctada fucata.

    PubMed

    Kong, Wei; Li, Shiguo; Xiang, Liang; Xie, Liping; Zhang, Rongqing

    2015-08-01

    Formation of the molluscan shell is believed to be an extracellular event mediated by matrix proteins. We report calcium carbonate mineralization mediated by Pinctada fucata mantle cells. Crystals only appeared when mantle cells were present in the crystallization solution. These crystals were piled up in highly ordered units and showed the typical characteristics of biomineralization products. A thin organic framework was observed after dissolving the crystals in EDTA. Some crystals had etched surfaces with a much smoother appearance than other parts. Mantle cells were observed to be attached to some of these smooth surfaces. These results suggest that mantle cells may be directly involved in the nucleation and remodeling process of calcium carbonate mineralization. Our result demonstrate the practicability of studying the mantle cell mechanism of biomineralization and contribute to the overall understanding of the shell formation process.

  8. Tubular electrodeposition of chitosan-carbon nanotube implants enriched with calcium ions.

    PubMed

    Nawrotek, Katarzyna; Tylman, Michał; Rudnicka, Karolina; Gatkowska, Justyna; Balcerzak, Jacek

    2016-07-01

    A new approach for obtaining chitosan-carbon nanotube implants enriched with calcium ions in the form of tubular hydrogels is fostered. The intended application of the hydrogels is tissue engineering, especially peripheral nervous tissue regeneration. The fabrication method, based on an electrodeposition phenomenon, shows significant advantages over current solutions as implants can now be obtained rapidly at any required dimensions. Thus, it may open a new avenue to treat patients with peripheral nerve injuries. Either single walled or multiwalled carbon nanotubes enhance the mechanical properties of the tubular hydrogels. The controlled presence of calcium ions, sourced from hydroxyapatite, is also expected to augment the regenerative response. Because in vitro cytotoxic assays on mouse cell lines (L929 fibroblasts and mHippoE-18 hippocampal cells) as well as pro-inflammatory tests on THP-1XBlue™ cells show that the manufactured implants are biocompatible, we next intend to evaluate their immune- and nervous-safety on an animal model.

  9. [The effect of crystallization of calcium carbonate on the secondary structure of pepsin].

    PubMed

    Zhu, Shu-fa; Tang, Jun-ming; Ma, Xiao-ming; Guo, Yu-ming; Zhang, Xiu-ying; Yang, Lin

    2003-06-01

    The effect of crystallization of calcium carbonate on the secondary structure of pepsin was studied by Fourier transform infrared spectroscopy, derivative, deconvolution and curve-fitting techniques in this paper. The result shows that the pure protein is composed of 24.38% alpha-helices, 29.91% beta-sheets, 39.22% beta-turns and 6.49% random structures, and the pepsin in the CaCO3/pepsin solution is composed of 2.09% alpha-helices, 93.304% beta-sheets, 4.60% beta-turns and 0.006% random structures. From these data we can see that the alpha-helices decrease and the beta-turns increase with the formation of the crystal of calcium carbonate. The essence of these changes is discussed in the paper.

  10. Comparative study of calcium alginate, activated carbon, and their composite beads on methylene blue adsorption.

    PubMed

    Hassan, A F; Abdel-Mohsen, A M; Fouda, Moustafa M G

    2014-02-15

    Three adsorbents, calcium alginate beads (AB), sodium hydroxide activated carbon based coconut shells (C), and calcium alginate/activated carbon composite beads (ACB) were prepared. Their textural properties were characterized by N2-adsorption at -196°C and scanning electron microscopy. The porosity, surface area and total pore volume of C>ACB>AB, but AB adsorbent was more acidic function groups more than the other adsorbents. Adsorption experiments were conducted to examine the effects of adsorbent dosage, pH, time, temperature and initial concentration of methylene blue. Methylene blue adsorption on C, AB and ACB was observed at pH>6 to avoid the competition of H(+). The amount of dye adsorbed increases as the adsorbent dosage increase. Adsorption of dye follows pseudo-second order mechanism. Thermodynamic studies show spontaneous and endothermic nature of the overall adsorption process.

  11. Effect of silk sericin on morphology and structure of calcium carbonate crystal

    NASA Astrophysics Data System (ADS)

    Zhao, Rui-Bo; Han, Hua-Feng; Ding, Shao; Li, Ze-Hao; Kong, Xiang-Dong

    2013-06-01

    In this paper, silk sericin was employed to regulate the mineralization of calcium carbonate (CaCO3). CaCO3 composite particles were prepared by the precipitation reaction of sodium carbonate with calcium chloride solution in the presence of silk sericin. The as-prepared samples were collected at different reaction time to study the crystallization process of CaCO3 by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The results showed that silk sericin significantly affected the morphology and crystallographic polymorph of CaCO3. With increasing the reaction time, the crystal phase of CaCO3 transferred from calcite dominated to vaterite dominated mixtures, while the morphology of CaCO3 changed from disk-like calcite crystal to spherical vaterite crystal. These studies showed the potential of silk sericin used as a template molecule to control the growth of inorganic crystal.

  12. The inhibition of calcium carbonate crystal growth by the cysteine-rich Mdm2 peptide.

    PubMed

    Dalas, E; Chalias, A; Gatos, D; Barlos, K

    2006-08-15

    The crystal growth of calcite, the most stable calcium carbonate polymorph, in the presence of the cysteine-rich Mdm2 peptide (containing 48 amino acids in the ring finger configuration), has been investigated by the constant composition technique. Crystallization took place exclusively on well-characterized calcite crystals in solutions supersaturated only with respect to this calcium carbonate salt. The kinetic results indicated a surface diffusion spiral growth mechanism. The presence of the Mdm2 peptide inhibited the crystal growth of calcite by 22-58% in the concentration range tested, through adsorption onto the active growth sites of the calcite crystal surface. The kinetic results favored a Langmuir-type adsorption model, and the value of the calculated affinity constant was k(aff)=147x10(4) dm(3)mol(-1), a(ads)=0.29. PMID:16678843

  13. Dehydration and crystallization of amorphous calcium carbonate in solution and in air.

    PubMed

    Ihli, Johannes; Wong, Wai Ching; Noel, Elizabeth H; Kim, Yi-Yeoun; Kulak, Alexander N; Christenson, Hugo K; Duer, Melinda J; Meldrum, Fiona C

    2014-01-01

    The mechanisms by which amorphous intermediates transform into crystalline materials are poorly understood. Currently, attracting enormous interest is the crystallization of amorphous calcium carbonate, a key intermediary in synthetic, biological and environmental systems. Here we attempt to unify many contrasting and apparently contradictory studies by investigating this process in detail. We show that amorphous calcium carbonate can dehydrate before crystallizing, both in solution and in air, while thermal analyses and solid-state nuclear magnetic resonance measurements reveal that its water is present in distinct environments. Loss of the final water fraction--comprising less than 15% of the total--then triggers crystallization. The high activation energy of this step suggests that it occurs by partial dissolution/recrystallization, mediated by surface water, and the majority of the particle then crystallizes by a solid-state transformation. Such mechanisms are likely to be widespread in solid-state reactions and their characterization will facilitate greater control over these processes.

  14. Development of antimicrobial water filtration hybrid material from bio source calcium carbonate and silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Apalangya, Vitus; Rangari, Vijaya; Tiimob, Boniface; Jeelani, Shaik; Samuel, Temesgen

    2014-03-01

    Biobased calcium carbonate and silver hybrid nanoparticles were synthesized using a simple mechanochemical milling technique. The XRD spectrum showed that the hybrid materials is composed of crystalline calcite and silver nanoparticles. The TEM results indicated that the silver nanoparticles are discrete, uncapped and well stabilized in the surface of the eggshell derived calcium carbonate particles. The silver nanoparticles are spherical in shape and 5-20 nm in size. The SEM studies indicated that the eggshells are in micron size with the silver nanoparticle embedded in their surface. The hybrid eggshell/silver nanocomposite exhibited superior inhibition of E. coli growth using the Kirby-Bauer discs diffusion assay and comparing the zone of inhibition around the filter paper disc impregnated with the hybrid particles against pristine silver nanoparticles.

  15. A transparent hybrid of nanocrystalline cellulose and amorphous calcium carbonate nanoparticles

    NASA Astrophysics Data System (ADS)

    Gebauer, Denis; Oliynyk, Vitaliy; Salajkova, Michaela; Sort, Jordi; Zhou, Qi; Bergström, Lennart; Salazar-Alvarez, German

    2011-09-01

    Nanocellulose hybrids are promising candidates for biodegradable multifunctional materials. Hybrids of nanocrystalline cellulose (NCC) and amorphous calcium carbonate (ACC) nanoparticles were obtained through a facile chemical approach over a wide range of compositions. Controlling the interactions between NCC and ACC results in hard, transparent structures with tunable composition, homogeneity and anisotropy.Nanocellulose hybrids are promising candidates for biodegradable multifunctional materials. Hybrids of nanocrystalline cellulose (NCC) and amorphous calcium carbonate (ACC) nanoparticles were obtained through a facile chemical approach over a wide range of compositions. Controlling the interactions between NCC and ACC results in hard, transparent structures with tunable composition, homogeneity and anisotropy. Electronic supplementary information (ESI) available: Additional experimental procedures and results. See DOI: 10.1039/c1nr10681c

  16. The Impact of Adsorbed Triethylene Glycol on Water Wettability of the {1014} Calcium Carbonate Surface

    NASA Astrophysics Data System (ADS)

    Olsen, R.

    2015-12-01

    Water flooding is increasingly being used as a method of enhanced oil recovery and frequently involves calcium carbonate reservoirs. Very often, thermodynamic conditions in the upper few hundred meters allow for hydrate formation. One possible method of preventing hydrates is to inject hydrate inhibitors such as triethylene glycol (TEG) into the reservoir. Thus, it is of importance to know how such glycols affect water wettability, which is an important factor defining the oil behavior in such reservoirs. Wettability of a surface is defined by the contact angle of a liquid drop on the surface. The stronger the liquid is attracted to the surface, the smaller the wetting angle becomes, implying an increased degree of wetting. Therefore, it is possible to gain qualitative knowledge of the change in wetting properties with respect to external influences by studying corresponding changes in free energy of adsorption of the liquid. In our work [1], we used molecular dynamics (MD) and Born-Oppenheimer molecular dynamics (BOMD) to study how adsorbed TEG on the {1014} calcium carbonate surface affected adsorbed water. We used the changes in density profiles of water to estimate changes in adsorption free energy of water. The adaptive biasing force (ABF) method was applied to TEG to calculate the adsorption free energy of TEG on the calcium carbonate surface. We found that water wetting of the calcium carbonate surface decreased in the presence of adsorbed TEG. [1] - Olsen, R.; Leirvik, K.; Kvamme, B.; Kuznetsova, T. Adsorption Properties of Triethylene Glycol on a Hydrated {1014} Calcite Surface and Its Effect on Adsorbed Water, Langmuir 2015, DOI: 10.1021/acs.langmuir.5b02228

  17. Capillarity creates single-crystal calcite nanowires from amorphous calcium carbonate.

    PubMed

    Kim, Yi-Yeoun; Hetherington, Nicola B J; Noel, Elizabeth H; Kröger, Roland; Charnock, John M; Christenson, Hugo K; Meldrum, Fiona C

    2011-12-23

    Single-crystal calcite nanowires are formed by crystallization of morphologically equivalent amorphous calcium carbonate (ACC) particles within the pores of track etch membranes. The polyaspartic acid stabilized ACC is drawn into the membrane pores by capillary action, and the single-crystal nature of the nanowires is attributed to the limited contact of the intramembrane ACC particle with the bulk solution. The reaction environment then supports transformation to a single-crystal product.

  18. Imaging calcium carbonate distribution in human sweat pore in vivo using nonlinear microscopy

    NASA Astrophysics Data System (ADS)

    Chen, Xueqin; Gasecka, Alicja; Formanek, Florian; Galey, Jean-Baptiste; Rigneault, Hervé

    2015-03-01

    Nonlinear microscopies, including two-photon excited autofluorescence (TPEF) and coherent anti-Stokes Raman scattering (CARS), were used to study individual human sweat pore morphology and topically applied antiperspirant salt penetration inside sweat pore, in vivo on human palms. Sweat pore inner morphology in vivo was imaged up to the depth of 100 μm by TPEF microscopy. The 3D penetration and distribution of "in situ calcium carbonate" (isCC), an antiperspirant salt model, was investigated using CARS microscopy.

  19. Macromolecule loading into spherical, elliptical, star-like and cubic calcium carbonate carriers.

    PubMed

    Parakhonskiy, Bogdan V; Yashchenok, Alexey M; Donatan, Senem; Volodkin, Dmitry V; Tessarolo, Francesco; Antolini, Renzo; Möhwald, Helmuth; Skirtach, Andre G

    2014-09-15

    We fabricated calcium carbonate particles with spherical, elliptical, star-like and cubical morphologies by varying relative salt concentrations and adding ethylene glycol as a solvent to slow down the rate of particle formation. The loading capacity of particles of different isotropic (spherical and cubical) and anisotropic (elliptical and star-like) geometries is investigated, and the surface area of such carriers is analysed. Potential applications of such drug delivery carriers are highlighted.

  20. Rapid hydrothermal flow synthesis and characterisation of carbonate- and silicate-substituted calcium phosphates

    PubMed Central

    Knowles, Jonathan C; Rehman, Ihtesham; Darr, Jawwad A

    2013-01-01

    A range of crystalline and nano-sized carbonate- and silicate-substituted hydroxyapatite has been successfully produced by using continuous hydrothermal flow synthesis technology. Ion-substituted calcium phosphates are better candidates for bone replacement applications (due to improved bioactivity) as compared to phase-pure hydroxyapatite. Urea was used as a carbonate source for synthesising phase pure carbonated hydroxyapatite (CO3-HA) with ≈5 wt% substituted carbonate content (sample 7.5CO3-HA) and it was found that a further increase in urea concentration in solution resulted in biphasic mixtures of carbonate-substituted hydroxyapatite and calcium carbonate. Transmission electron microscopy images revealed that the particle size of hydroxyapatite decreased with increasing urea concentration. Energy-dispersive X-ray spectroscopy result revealed a calcium deficient apatite with Ca:P molar ratio of 1.45 (±0.04) in sample 7.5CO3-HA. For silicate-substituted hydroxyapatite (SiO4-HA) silicon acetate was used as a silicate ion source. It was observed that a substitution threshold of ∼1.1 wt% exists for synthesis of SiO4-HA in the continuous hydrothermal flow synthesis system, which could be due to the decreasing yields with progressive increase in silicon acetate concentration. All the as-precipitated powders (without any additional heat treatments) were analysed using techniques including Transmission electron microscopy, X-ray powder diffraction, Differential scanning calorimetry, Thermogravimetric analysis, Raman spectroscopy and Fourier transform infrared spectroscopy. PMID:22983020

  1. Chemical immobilization of Pb, Cu, and Cd by phosphate materials and calcium carbonate in contaminated soils.

    PubMed

    Huang, Guoyong; Su, Xiaojuan; Rizwan, Muhammad Shahid; Zhu, Yifei; Hu, Hongqing

    2016-08-01

    Soil contamination with toxic metals has increasingly become a global concern over the past few decades. Phosphate and carbonate compounds are good passivation materials for Pb immobilization, while the effect of phosphate and carbonate on the immobilization of multiple heavy metals (Pb, Cu, and Cd) in contaminated soils was seldom investigated. In this study, bone meal (BM), phosphate rock (PR), oxalic acid-activated phosphate rock (APR), super phosphate (SP), and calcium carbonate (CC) were added to the contaminated soils to evaluate the effect of phosphate materials and calcium carbonate on the immobilization of Pb, Cu, and Cd. The results showed that the pH of the treated soils increased 1.3-2.7, except SP which decreased 0.5 at most. Compared to the control treatment, all phosphates and calcium carbonate added to the polluted soils increased the fraction of residual metals, and the application of APR, PR, BM, and CC significantly reduced exchangeable and carbonate-bound fraction metals. PR and APR were the most effective for the immobilization of Pb, Cu, and Cd in the soils among these materials. Moreover, the concentrations of all metals in the toxicity characteristic leaching procedure (TCLP) leachate decreased with increasing amounts of amendments, and the concentrations of Pb in the TCLP leachate for soils treated with PR and APR were below the nonhazardous regulatory limit of 5 mg L(-1) (US Environmental Protection Agency). Based on our results, phosphate rock and oxalic acid-activated phosphate rock are effective in the immobilization of multiple metals by reducing their mobility in the co-contaminated soils. PMID:27197655

  2. Chemical immobilization of Pb, Cu, and Cd by phosphate materials and calcium carbonate in contaminated soils.

    PubMed

    Huang, Guoyong; Su, Xiaojuan; Rizwan, Muhammad Shahid; Zhu, Yifei; Hu, Hongqing

    2016-08-01

    Soil contamination with toxic metals has increasingly become a global concern over the past few decades. Phosphate and carbonate compounds are good passivation materials for Pb immobilization, while the effect of phosphate and carbonate on the immobilization of multiple heavy metals (Pb, Cu, and Cd) in contaminated soils was seldom investigated. In this study, bone meal (BM), phosphate rock (PR), oxalic acid-activated phosphate rock (APR), super phosphate (SP), and calcium carbonate (CC) were added to the contaminated soils to evaluate the effect of phosphate materials and calcium carbonate on the immobilization of Pb, Cu, and Cd. The results showed that the pH of the treated soils increased 1.3-2.7, except SP which decreased 0.5 at most. Compared to the control treatment, all phosphates and calcium carbonate added to the polluted soils increased the fraction of residual metals, and the application of APR, PR, BM, and CC significantly reduced exchangeable and carbonate-bound fraction metals. PR and APR were the most effective for the immobilization of Pb, Cu, and Cd in the soils among these materials. Moreover, the concentrations of all metals in the toxicity characteristic leaching procedure (TCLP) leachate decreased with increasing amounts of amendments, and the concentrations of Pb in the TCLP leachate for soils treated with PR and APR were below the nonhazardous regulatory limit of 5 mg L(-1) (US Environmental Protection Agency). Based on our results, phosphate rock and oxalic acid-activated phosphate rock are effective in the immobilization of multiple metals by reducing their mobility in the co-contaminated soils.

  3. Compaction of functionalized calcium carbonate, a porous and crystalline microparticulate material with a lamellar surface.

    PubMed

    Stirnimann, Tanja; Atria, Susanna; Schoelkopf, Joachim; Gane, Patrick A C; Alles, Rainer; Huwyler, Jörg; Puchkov, Maxim

    2014-05-15

    In the present study, we aimed to characterize the compressibility and compactibility of the novel pharmaceutical excipient, functionalized calcium carbonate (FCC). We studied three FCC modifications and compared the values for compressibility and compactibility with mannitol, microcrystalline cellulose (MCC), and ground calcium carbonate (CC 330) as well as mixtures of paracetamol and MCC or FCC at drug loads of 0%, 25%, 50%, 75%, and 100% (w/w). We used Heckel analysis, modified Heckel analysis, and Leuenberger analysis to characterize the compaction and compression behavior of the mixtures. Compaction analysis of FCC showed this material to markedly differ from ground calcium carbonate, exhibiting properties, i.e. plastic deformability, similar to those of MCC. This effect was attributed to the highly lamellar structure of FCC particles whose thickness is of the order of a single crystal unit cell. According to Leuenberger parameters, we concluded that FCC-based tablet formulations had mechanical properties equal or superior to those formulated with MCC. FCC tablets with high tensile strength were obtained already at low compressive pressures. Owing to these favorable properties (i.e. marked tensile strength and porosity), FCC promises to be suitable for the preparation of solid dosage forms.

  4. Calcium carbonate crystal growth beneath Langmuir monolayers of acidic β-hairpin peptides.

    PubMed

    Gong, Haofei; Yang, Yi; Pluntke, Manuela; Marti, Othmar; Majer, Zsuzsa; Sewald, Norbert; Volkmer, Dirk

    2014-11-28

    Four amphiphilic peptides with designed hairpin structure were synthesized and their monolayers were employed as model systems to study biologically inspired calcium carbonate crystallization. Langmuir monolayers of hairpin peptides were investigated by surface pressure area isotherms, surface potential isotherms, Brewster angle microscopy (BAM), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy. A β-hairpin conformation was found for all peptides at the air-water interface although their packing arrangements seem to be different. Crystallization of calcium carbonate under these peptide monolayers was investigated at different surface pressures and growth times both by in situ optical microscopy, BAM and ex situ investigations such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). An amorphous calcium carbonate precursor was found at the initial crystallization stage. The crystallization process occurred in three stages. It starts from the nucleation of amorphous particles being a kinetically controlled process. Crystal nuclei subsequently aggregate to large particles and vaterite crystals start to form inside the amorphous layer, with the monolayer fluidity exerting an important role. The third process includes the re-crystallization of vaterite to calcite, which is thermodynamically controlled by monolayer structural factors including the monolayer flexibility and packing arrangement of the polar headgroups. Thus, the kinetic factors, monolayer fluidity and flexibility as well as structure factors govern the crystal morphology and polymorph distribution simultaneously and synergistically.

  5. EPR investigation of UV light effect on calcium carbonate powders with different grain sizes.

    PubMed

    Kabacińska, Zuzanna; Krzyminiewski, Ryszard; Dobosz, Bernadeta

    2014-06-01

    This study is based on investigation of calcium carbonate powders with different grain sizes exposed to UV light. Calcium carbonate is widely used in many branches of industry, e.g. as a filler for polymer materials; therefore, knowing its properties, among them also its reaction to UV light, is essential. Samples of powdered calcium carbonate with average grain sizes of 69 and 300 nm and 2.1, 6, 16, 25 µm were used in this investigation. Measurements were performed at room temperature using EPR X-band spectrometer, and they have shown the additional signals induced by the light from Hg lamp. The effect of annealing of the micro-grain samples was also studied. The spectra of four micro-grain samples after irradiation are similar, but there are differences between them and the other two powders, which could be related to the different sizes of their grains. Further studies based on these preliminary results may prove useful in research of photodegradation of CaCO3-filled materials, as well as helpful in increasing the accuracy of dating of archaeological and geological objects.

  6. Fracture Sealing with Microbially-Induced Calcium Carbonate Precipitation: A Field Study.

    PubMed

    Phillips, Adrienne J; Cunningham, Alfred B; Gerlach, Robin; Hiebert, Randy; Hwang, Chiachi; Lomans, Bartholomeus P; Westrich, Joseph; Mantilla, Cesar; Kirksey, Jim; Esposito, Richard; Spangler, Lee

    2016-04-01

    A primary environmental risk from unconventional oil and gas development or carbon sequestration is subsurface fluid leakage in the near wellbore environment. A potential solution to remediate leakage pathways is to promote microbially induced calcium carbonate precipitation (MICP) to plug fractures and reduce permeability in porous materials. The advantage of microbially induced calcium carbonate precipitation (MICP) over cement-based sealants is that the solutions used to promote MICP are aqueous. MICP solutions have low viscosities compared to cement, facilitating fluid transport into the formation. In this study, MICP was promoted in a fractured sandstone layer within the Fayette Sandstone Formation 340.8 m below ground surface using conventional oil field subsurface fluid delivery technologies (packer and bailer). After 24 urea/calcium solution and 6 microbial (Sporosarcina pasteurii) suspension injections, the injectivity was decreased (flow rate decreased from 1.9 to 0.47 L/min) and a reduction in the in-well pressure falloff (>30% before and 7% after treatment) was observed. In addition, during refracturing an increase in the fracture extension pressure was measured as compared to before MICP treatment. This study suggests MICP is a promising tool for sealing subsurface fractures in the near wellbore environment. PMID:26911511

  7. Fracture Sealing with Microbially-Induced Calcium Carbonate Precipitation: A Field Study.

    PubMed

    Phillips, Adrienne J; Cunningham, Alfred B; Gerlach, Robin; Hiebert, Randy; Hwang, Chiachi; Lomans, Bartholomeus P; Westrich, Joseph; Mantilla, Cesar; Kirksey, Jim; Esposito, Richard; Spangler, Lee

    2016-04-01

    A primary environmental risk from unconventional oil and gas development or carbon sequestration is subsurface fluid leakage in the near wellbore environment. A potential solution to remediate leakage pathways is to promote microbially induced calcium carbonate precipitation (MICP) to plug fractures and reduce permeability in porous materials. The advantage of microbially induced calcium carbonate precipitation (MICP) over cement-based sealants is that the solutions used to promote MICP are aqueous. MICP solutions have low viscosities compared to cement, facilitating fluid transport into the formation. In this study, MICP was promoted in a fractured sandstone layer within the Fayette Sandstone Formation 340.8 m below ground surface using conventional oil field subsurface fluid delivery technologies (packer and bailer). After 24 urea/calcium solution and 6 microbial (Sporosarcina pasteurii) suspension injections, the injectivity was decreased (flow rate decreased from 1.9 to 0.47 L/min) and a reduction in the in-well pressure falloff (>30% before and 7% after treatment) was observed. In addition, during refracturing an increase in the fracture extension pressure was measured as compared to before MICP treatment. This study suggests MICP is a promising tool for sealing subsurface fractures in the near wellbore environment.

  8. Tribological and antioxidation synergistic effect study of sulfonate-modified nano calcium carbonate.

    PubMed

    Zhongyi, He; Liping, Xiong; Sheng, Han; Aixi, Chen; Jianwei, Qiu; Xisheng, Fu

    2013-01-01

    A middle base number sulphonate-modified nano calcium carbonate (SMC) with an average size of 35 nm was synthesized, and its tribological and antioxidation synergistic behaviors with ashless antioxidant N-phenyl-α-naphthylamine (T531) in hydrogenated oil (5Cst) were evaluated. The results demonstrate that adding this synthesized additive even at a low amount (<2.0 wt.%) can evidently improve its load-carrying capacity by 1.5 times and enhance its antiwear performance; in addition, the friction-reducing effect of additive in the high load was better than that in low load. The SMC have a good synergistic antioxidation effect with T531, which verifies the nano calcium carbonate compound was a kind of multifunctional and high-performance additive. The chemical composition of the rubbing surface which formed on the boundary film was analyzed by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results indicating that the excellent antiwear and load-carrying performance could be attributed to the forming of boundary lubrication film which composed of calcium carbonate, oxides, ferrites, sulphide and FeSO4, and so on. Its ability to increase oxidation free energy of base oil is the main reason for increasing its antioxidant collaboration property with ashless antioxidant T531. PMID:23658705

  9. Tribological and Antioxidation Synergistic Effect Study of Sulfonate-Modified Nano Calcium Carbonate

    PubMed Central

    Zhongyi, He; Liping, Xiong; Sheng, Han; Aixi, Chen; Jianwei, Qiu; Xisheng, Fu

    2013-01-01

    A middle base number sulphonate-modified nano calcium carbonate (SMC) with an average size of 35 nm was synthesized, and its tribological and antioxidation synergistic behaviors with ashless antioxidant N-phenyl-α-naphthylamine (T531) in hydrogenated oil (5Cst) were evaluated. The results demonstrate that adding this synethesized additive even at a low amount (<2.0 wt.%) can evidently improve its load-carrying capacity by 1.5 times and enhance its antiwear performance; in addition, the friction-reducing effect of additive in the high load was better than that in low load. The SMC have a good synergistic antioxidation effect with T531, which verifies the nano calcium carbonate compound was a kind of multifunctional and high-performance additive. The chemical composition of the rubbing surface which formed on the boundary film was analyzed by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results indicating that the excellent antiwear and load-carrying performance could be attributed to the forming of boundary lubrication film which composed of calcium carbonate, oxides, ferrites, sulphide and FeSO4, and so on. Its ability to increase oxidation free energy of base oil is the main reason for increasing its antioxidant collaboration property with ashless antioxidant T531. PMID:23658705

  10. Remediation of heavy metal contaminated groundwater originated from abandoned mine using lime and calcium carbonate.

    PubMed

    Lee, Minhee; Paik, In Sung; Kim, Insu; Kang, Hyunmin; Lee, Sanghoon

    2007-06-01

    Column and pilot scale experiments for a chemical treatment involving the use of coagulants to remediate heavy metal contaminated groundwater were performed. Granulated lime (Ca(OH)(2)) and calcium carbonate (CaCO(3)) were used as coagulants and contaminated groundwater obtained at an abandoned Fe-mine in Korea was used for the experiments. The main removal mechanism of heavy metals in the experiments was "sweep precipitation" by coagulation. Using granulated lime as a coagulant in the column experiment, more than 98% of As and Ni were removed from artificially contaminated water. When granulated calcium carbonate was used in the artificially contaminated water, the removal efficiencies of Ni and Zn were more than 97%, but As removal efficiency was lower than 50%. For the continuous column experiment with mixed lime and calcium carbonate at a 1:1 (v/v) ratio, almost all As was removed and more than 98 % of Ni was removed. For pilot scale experiments (acryl tank: 34 cm in length and 24 cm in diameter), the removal efficiencies of As and Cd were above 96% for 150l groundwater treatment and their accumulated removal capacities linearly maintained. This suggests that coagulants could treat more than 22 times greater groundwater volume compared with the volume of coagulants used.

  11. Carbide-Derived Carbon Films for Integrated Electrochemical Energy Storage

    NASA Astrophysics Data System (ADS)

    Heon, Min

    Active RFID tags, which can communicate over tens or even hundreds of meters, MEMS devices of several microns in size, which are designed for the medical and pharmaceutical purposes, and sensors working in wireless monitoring systems, require microscale power sources that are able to provide enough energy and to satisfy the peak power demands in those applications. Supercapacitors have not been an attractive candidate for micro-scale energy storage, since most nanoporous carbon electrode materials are not compatible with micro-fabrication techniques and have failed to meet the requirements of high volumetric energy density and small form factor for power supplies for integrated circuits or microelectronic devices or sensors. However, supercapacitors can provide high power density, because of fast charging/discharging, which can enable self-sustaining micro-modules when combined with energy-harvesting devices, such as solar cell, piezoelectric or thermoelectric micro-generators. In this study, carbide-derived carbon (CDC) films were synthesized via vacuum decomposition of carbide substrates and gas etching of sputtered carbide thin films. This approach allowed manufacturing of porous carbon films on SiC and silicon substrates. CDC films were studied for micro-supercapacitor electrodes, and showed good double layer capacitance. Since the gas etching technique is compatible with conventional micro-device fabrication processes, it can be implemented to manufacture integrated on-chip supercapacitors on silicon wafers.

  12. Plant growth-rate dependence of detrital carbon storage in ecosystems

    SciTech Connect

    Cebrian, J.; Duarte, C.M.

    1995-06-16

    Detrital carbon accumulation accounts for most of an ecosystem`s capacity to store organic carbon because the carbon contained as plant detritus exceeds that stored in living plants by about threefold. A comparative analysis of the mass and turnover of detrital carbon in ecosystems demonstrates that these properties are strongly related to the turnover rate of the dominant primary producers and are poorly related to ecosystem primary production. These results contribute to an understanding of the factors that control carbon storage in ecosystems and the role of carbon storage in the global carbon budget. 24 refs., 3 figs.

  13. Degradation and swelling issues of poly-(d,l-lactide)/β-tricalcium phosphate/calcium carbonate composites for bone replacement.

    PubMed

    Abert, Jessica; Amella, Alessandro; Weigelt, Simone; Fischer, Horst

    2016-02-01

    Recently a tri-phase material consisting of poly-(d,l-lactide) (PDLLA), β-tricalcium phosphate (β-TCP), and calcium carbonate (CC) was proposed as a novel bone substitute candidate. β-TCP is suitable because of its bone-like mineral phase, PDLLA is introduced as a biodegradable adhesive phase, and CC is essential for buffering the acidic degradation of the lactate component. We hypothesize that the amounts of the three different components in the composite material must be carefully balanced in order to avoid issues such as accelerated degradation or pronounced volumetric swelling. To prove this, granulates made of different mixing ratios of the tri-phase compound were prepared by grinding. Specimens of the different compounds were manufactured by a hot pressing process. The bending strength of the specimens was determined before and after storing in demineralized water and phosphate buffered saline (PBS). The particle size of the compound granulates was smaller than 100µm. A ratio of 60wt% of the PDLLA component indicated the best compromise between stability of test specimens based on a strong melting network and bone-like properties. The specimens exhibited a bending strength up to 90MPa. The strength increased with an increasing ratio of β-TCP to calcium carbonate (based on 60wt% PDLLA). A vast volumetric swelling up to 40%, and thus a huge reduction of the bending strength, was observed during the storage of specimens in PBS. A swelling and thus a volume increase could be critical, especially for using the tri-phase bone substitute compound as 3D scaffold with defined dimensions. This must be considered with regard to the composition of the compound and the scaffold design.

  14. Bacillus megaterium mediated mineralization of calcium carbonate as biogenic surface treatment of green building materials.

    PubMed

    Dhami, Navdeep Kaur; Reddy, M Sudhakara; Mukherjee, Abhijit

    2013-12-01

    Microbially induced calcium carbonate precipitation is a biomineralization process that has various applications in remediation and restoration of range of building materials. In the present study, calcifying bacteria, Bacillus megaterium SS3 isolated from calcareous soil was applied as biosealant to enhance the durability of low energy, green building materials (soil-cement blocks). This bacterial isolate produced high amounts of urease, carbonic anhydrase, extra polymeric substances and biofilm. The calcium carbonate polymorphs produced by B. megaterium SS3 were analyzed by scanning electron microscopy, confocal laser scanning microscopy, X-ray diffraction and Fourier transmission infra red spectroscopy. These results suggested that calcite is the most predominant carbonate formed by this bacteria followed by vaterite. Application of B. megaterium SS3 as biogenic surface treatment led to 40 % decrease in water absorption, 31 % decrease in porosity and 18 % increase in compressive strength of low energy building materials. From the present investigation, it is clear that surface treatment of building materials by B. megaterium SS3 is very effective and eco friendly way of biodeposition of coherent carbonates that enhances the durability of building materials.

  15. Bacillus megaterium mediated mineralization of calcium carbonate as biogenic surface treatment of green building materials.

    PubMed

    Dhami, Navdeep Kaur; Reddy, M Sudhakara; Mukherjee, Abhijit

    2013-12-01

    Microbially induced calcium carbonate precipitation is a biomineralization process that has various applications in remediation and restoration of range of building materials. In the present study, calcifying bacteria, Bacillus megaterium SS3 isolated from calcareous soil was applied as biosealant to enhance the durability of low energy, green building materials (soil-cement blocks). This bacterial isolate produced high amounts of urease, carbonic anhydrase, extra polymeric substances and biofilm. The calcium carbonate polymorphs produced by B. megaterium SS3 were analyzed by scanning electron microscopy, confocal laser scanning microscopy, X-ray diffraction and Fourier transmission infra red spectroscopy. These results suggested that calcite is the most predominant carbonate formed by this bacteria followed by vaterite. Application of B. megaterium SS3 as biogenic surface treatment led to 40 % decrease in water absorption, 31 % decrease in porosity and 18 % increase in compressive strength of low energy building materials. From the present investigation, it is clear that surface treatment of building materials by B. megaterium SS3 is very effective and eco friendly way of biodeposition of coherent carbonates that enhances the durability of building materials. PMID:23793943

  16. Structuralization of Ca(2+)-Based Metal-Organic Frameworks Prepared via Coordination Replication of Calcium Carbonate.

    PubMed

    Sumida, Kenji; Hu, Ming; Furukawa, Shuhei; Kitagawa, Susumu

    2016-04-01

    The emergence of metal-organic frameworks (MOFs) as potential candidates to supplant existing adsorbent types in real-world applications has led to an explosive growth in the number of compounds available to researchers, as well as in the diversity of the metal salts and organic linkers from which they are derived. In this context, the use of carbonate-based precursors as metal sources is of interest due to their abundance in mineral deposits and their reaction chemistry with acids, resulting in just water and carbon dioxide as side products. Here, we have explored the use of calcium carbonate as a metal source and demonstrate its versatility as a precursor to several known frameworks, as well as a new flexible compound based on the 2,5-dihydroxybenzoquinone (H2dhbq) linker, Ca(dhbq)(H2O)2. Furthermore, inspired by the ubiquity and unique structures of biomineralized forms of calcium carbonate, we also present examples of the preparation of superstructures of Ca-based MOFs via the coordination replication technique. In all, the results confirm the suitability of carbonate-based metal sources for the preparation of MOFs and further expand upon the growing scope of coordination replication as a convenient strategy for the preparation of structuralized materials. PMID:27002690

  17. Dissolved Calcium and Magnesium Carbonates Promote Arsenate Release From Ferrihydrite in Flow Systems

    NASA Astrophysics Data System (ADS)

    Saalfield, S. L.; Bostick, B. C.

    2007-12-01

    Field data from water systems around the world have shown that arsenic can reach toxic concentrations in dynamic groundwater systems. This is generally in contrast to analogous static systems at circumneutral pH, where arsenic is strongly retained by sorption to iron (hydr)oxides. Our research examines the effect of calcium and magnesium carbonates on As(V) mobility. In both dynamic flow and static experiments, arsenate was pre- sorbed to poorly crystalline iron hydroxides (1-10% sorption capacity), with varying aqueous compositions including calcium, magnesium, carbonate, sulfate, lactate, and other common groundwater species (pH 7.5-8). Thus we investigated how the dissolution of common carbonate minerals, specifically CaCO3 and MgCO3, affect arsenic behavior in the context of groundwater solutions. Under static (batch) conditions, no measurable arsenic (<10 μg/L) is released into solutions containing alkaline earth metals (AEMs) and carbonates. When elevated concentrations of AEMs and carbonate are introduced by dynamic flow, however, arsenic is mobilized at up to 500 μg/L, releasing significant proportions the total arsenic present. This is only the case when both of these species are present; with other common ion pairs, little to no arsenic is released. These results indicate that arsenate adsorption is kinetically controlled under flow conditions, resulting in very different mobility relative to otherwise equivalent static systems. Furthermore, the combination of alkaline earth metals and carbonates promotes As(V) mobility in column-based systems. We propose that these phenomena indicate a combination of physical and chemical effects by which diffusion limitation becomes dominant in limiting arsenic sorption in flow systems. Many carbonate-buffered aquifers, as well as those undergoing rapid mineralization of organic matter, could be affected by these processes of AEM-carbonate-limited sorption and increased arsenic mobility.

  18. Synthesis and characterization of carbonated hydroxyapatite and bioinspired polymer-calcium phosphate nanocomposites

    NASA Astrophysics Data System (ADS)

    Yusufoglu, Yusuf

    Taking the inspiration from natural bone, where collagen provides sites for the nucleation and growth of carbonated hydroxyapatite, we have developed self-assembling calcium phosphate-block copolymer nanocomposites by using a bottom-up approach. In this regard, self-assembling thermo-reversibly gelling block copolymers based on the nonionic, zwitterionic, anionic, block copolymers conjugated to hydroxyapatite-nucleating peptides, and polylysine-polyleucine diblock copoly-peptides were employed as templates for the precipitation of nano-sized calcium phosphates from aqueous solutions. Calcium phosphate nanocrystals were formed at the polymer-inorganic interface presumably nucleated by the ionic interactions. Solid-state NMR, XRD, TEM, TGA, FTIR and X-ray scattering techniques were used to characterize the nanocomposites. NMR and scattering measurements of polymer-inorganic gel composites proved nanocomposite formation and templating by the polymer micelles. The inorganic fraction of the nanocomposites was found to vary between 30-55 wt%. TEM studies showed that the morphology and the size of the hydroxyapatite crystals in the nanocomposites were similar to the apatite in the bone. The findings in our studies provide information for developing guidelines for design of novel HAp-polymer nanocomposites and for the understanding of the mechanism of biomineralization. Moreover, this study may also offer routes for bioinspired bottom-up approaches for the development of a number of nanostructured composites including injectable nanocomposite biomaterials for potential orthopedic applications. As a part of the present study, the carbonate incorporation into the hydroxyapatite lattice under various pH conditions was also investigated. Crystalline sodium and carbonate containing calcium hydroxyapatite (NaCO 3HAp) powders were prepared using an oxidative decomposition of calcium-EDTA chelates in the sodium phosphate solution with hydrogen peroxide. Depending on pH, spherical

  19. Biological Origin of Micro-laminated Calcium Carbonate Deposits on Antarctic Rock Surfaces

    NASA Astrophysics Data System (ADS)

    Farmer, M.; Stone, J. O.

    2001-12-01

    We have observed and sampled patchy encrustations of calcium carbonate on rock surfaces in East and West Antarctica. Individual disk-like deposits are up to 1 cm across and a few mm thick, but in places coalesce to form more extensive, colloform coatings. We have observed these deposits on substrates of granite, sandstone, and schist. Their distribution appears similar to that of Antarctic lichens and endolithic algae, extending up to ca. 1000m elevation, but has no consistent relationship to snow drifts, solar radiation, or prevailing winds. The morphology and position of the deposits are distinct from sub-glacial carbonate precipitates. In Marie Byrd Land, the encrustations occur on the surfaces exposed by deglaciation within the past 5000 yrs, and the sample from East Antarctica contains live C-14 (M. Mabin, pers. comm.), suggesting a possible biological origin Electron microprobe and SEM examination of cross-sectioned specimens reveals micron-scale layering of predominantly calcium carbonate, but with a number of bright laminae in SEM images, believed to be calcium fluoride. Sections closely resemble desert varnish in micro-morphology, though not in mineralogy. Isotopic analysis of an organic carbon extract (as opposed to C from the CaCO3 itself) gave a delta C-13 PDB value of -23.3 per mil, similar to values expected in carbon of biological origin. However, we have no proof yet that the carbon analyzed was produced by organisms within the encrustation, rather than being entrapped during an inorganic precipitation process. To investigate the possible biological origin of this material, we attempted to sequence the 16S segment of rRNA in the organic extract, but have not yet completed successful PCR replication. We are continuing attempts to isolate and analyze the pertinent genetic material. The micro-morphology, strongly negative delta C-13 and presence of live C-14 suggest a biological process for precipitation of these calcium carbonate deposits. We hope to

  20. Purifications of calcium carbonate and molybdenum oxide powders for neutrinoless double beta decay experiment, AMoRE

    SciTech Connect

    Park, HyangKyu

    2015-08-17

    The AMoRE (Advanced Mo based Rare process Experiment) collaboration is going to use calcium molybdate crystals to search for neutrinoless double beta decay of {sup 100}Mo isotope. In order to make the crystal, we use calcium carbonate and molybdenum oxide powders as raw materials. Therefore it is highly necessary to reduce potential sources for radioactive backgrounds such as U and Th in the powders. In this talk, we will present our studies for purification of calcium carbonate and molybdenum oxide powders.

  1. CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    CALCIUM CHLORIDE PLANT LOOKING EAST. CALCIUM CHLORIDE BUILDING IN CENTER, CALCIUM CHLORIDE STORAGE BUILDING ON RIGHT WITH SA (SODA ASH) BUILDING IN RIGHT BACKGROUND. - Solvay Process Company, Calcium Chloride Plant, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

  2. Integrated Assessment Modeling for Carbon Storage Risk and Uncertainty Quantification

    NASA Astrophysics Data System (ADS)

    Bromhal, G. S.; Dilmore, R.; Pawar, R.; Stauffer, P. H.; Gastelum, J.; Oldenburg, C. M.; Zhang, Y.; Chu, S.

    2013-12-01

    The National Risk Assessment Partnership (NRAP) has developed tools to perform quantitative risk assessment at site-specific locations for long-term carbon storage. The approach that is being used is to divide the storage and containment system into components (e.g., reservoirs, seals, wells, groundwater aquifers), to develop detailed models for each component, to generate reduced order models (ROMs) based on the detailed models, and to reconnect the reduced order models within an integrated assessment model (IAM). CO2-PENS, developed at Los Alamos National Lab, is being used as the IAM for the simulations in this study. The benefit of this approach is that simulations of the complete system can be generated on a relatively rapid time scale so that Monte Carlo simulation can be performed. In this study, hundreds of thousands of runs of the IAMs have been generated to estimate likelihoods of the quantity of CO2 released to the atmosphere, size of aquifer impacted by pH, size of aquifer impacted by TDS, and size of aquifer with different metals concentrations. Correlations of the output variables with different reservoir, seal, wellbore, and aquifer parameters have been generated. Importance measures have been identified, and inputs have been ranked in the order of their impact on the output quantities. Presentation will describe the approach used, representative results, and implications for how the Monte Carlo analysis is implemented on uncertainty quantification.

  3. Fresh Water Generation from Aquifer-Pressured Carbon Storage

    SciTech Connect

    Aines, R D; Wolery, T J; Bourcier, W L; Wolfe, T; Haussmann, C

    2010-02-19

    Can we use the pressure associated with sequestration to make brine into fresh water? This project is establishing the potential for using brine pressurized by Carbon Capture and Storage (CCS) operations in saline formations as the feedstock for desalination and water treatment technologies including reverse osmosis (RO) and nanofiltration (NF). Possible products are: Drinking water, Cooling water, and Extra aquifer space for CO{sub 2} storage. The conclusions are: (1) Many saline formation waters appear to be amenable to largely conventional RO treatment; (2) Thermodynamic modeling indicates that osmotic pressure is more limiting on water recovery than mineral scaling; (3) The use of thermodynamic modeling with Pitzer's equations (or Extended UNIQUAC) allows accurate estimation of osmotic pressure limits; (4) A general categorization of treatment feasibility is based on TDS has been proposed, in which brines with 10,000-85,000 mg/L are the most attractive targets; (5) Brines in this TDS range appear to be abundant (geographically and with depth) and could be targeted in planning future CCS operations (including site selection and choice of injection formation); and (6) The estimated cost of treating waters in the 10,000-85,000 mg/L TDS range is about half that for conventional seawater desalination, due to the anticipated pressure recovery.

  4. Healing and Preventive Effects of Calcium Alginate on Carbon Tetrachloride Induced Liver Injury in Rats

    PubMed Central

    Khotimchenko, Yuri S.; Khotimchenko, Maxim Y.

    2004-01-01

    The purpose of this study was to investigate the pharmacological effects of calcium alginate on carbon tetrachloride (CCL4)-induced hepatotoxicity in rats. The study included two experiments. In the first experiment the animals were given daily CCL4 through gavage for 7 days and then 10, 50, or 250 mg/kg b.w. of calcium alginate for 21 days. The increased bilirubin level, enhanced alanine and aspartate aminotransferase activity in plasma and reduced liver glycogen content induced by CCL4 were partly normalized by alginate administration in a dose-dependent manner. In addition, alginate significantly improved CCL4-induced alterations of pro-oxidant and antioxidant biochemical parameters in liver and plasma compared to those of rats administered CCL4. In the second experiment the animals were given daily 10, 50 or 250 mg/kg b.w. of calcium alginate for 21 days before 7-day administration of CCL4. Pretreatment with alginate before CCL4 administration resulted in significantly inhibited increase of the blood enzymatic activities of alanine and aspartate aminotransferases and bilirubin level in a dose-dependent manner. Also, preliminary administration of alginate prevented elevation of lipid peroxidation products and reduction of liver glutathione content in rats given CCL4. These results suggest that calcium alginate exerts healing and preventive effects on CCL4-induced hepatotoxicity in rats.

  5. Application of pulsed spark discharge for calcium carbonate precipitation in hard water.

    PubMed

    Yang, Yong; Kim, Hyoungsup; Starikovskiy, Andrey; Fridman, Alexander; Cho, Young I

    2010-06-01

    The effect of underwater pulsed spark discharge on the precipitation of dissolved calcium ions was investigated in the present study. Water samples with different calcium hardness were prepared by continuous evaporation of tap water using a laboratory cooling tower. It was shown that the concentration of calcium ions dropped by 20-26% after 10-min plasma treatment, comparing with no drop for untreated cases. A laser particle counting method demonstrated that the total number of solid particles suspended in water increased by over 100% after the plasma treatment. The morphology and the crystal form of the particles were identified by both scanning electron microscopy and X-ray diffraction. Calcite with rhombohedron morphology was observed for plasma treated cases, comparing with the round structure observed for no-treatment cases. It was hypothesized that the main mechanisms for the plasma-assisted calcium carbonate precipitation might include electrolysis, local heating in the vicinity of plasma channel and a high electric field at the tip of plasma streamers, inducing structural changes in the electric double layer of hydrated ions. PMID:20494397

  6. Incorporation of lead into calcium carbonate granules secreted by earthworms living in lead contaminated soils

    NASA Astrophysics Data System (ADS)

    Fraser, A.; Lambkin, D. C.; Lee, M. R.; Schofield, P. F.; Mosselmans, J. F. W.; Hodson, M. E.

    2011-05-01

    The influence of soil organisms on metal mobility and bioavailability in soils is not currently fully understood. We conducted experiments to determine whether calcium carbonate granules secreted by the earthworm Lumbricus terrestris could incorporate and immobilise lead in lead- and calcium-amended artificial soils. Soil lead concentrations were up to 2000 mg kg -1 and lead:calcium ratios by mass were 0.5-8. Average granule production rates of 0.39 ± 0.04 mg calcite earthworm -1 day -1 did not vary with soil lead concentration. The lead:calcium ratio in granules increased significantly with that of the soil ( r2 = 0.81, p = 0.015) with lead concentrations in granules reaching 1577 mg kg -1. X-ray diffraction detected calcite and aragonite in the granules with indications that lead was incorporated into the calcite at the surface of the granules. In addition to the presence of calcite and aragonite X-ray absorption spectroscopy indicated that lead was present in the granules mainly as complexes sorbed to the surface but with traces of lead-bearing calcite and cerussite. The impact that lead-incorporation into earthworm calcite granules has on lead mobility at lead-contaminated sites will depend on the fraction of total soil lead that would be otherwise mobile.

  7. Climate warming shifts carbon allocation from stemwood to roots in calcium-depleted spruce forests

    NASA Astrophysics Data System (ADS)

    Lapenis, Andrei; Lawrence, Gregory; Buyantuev, Alexander

    2015-04-01

    Increased greening of northern forests, measured by the Normalized Difference Vegetation Index (NDVI), has been presented as evidence that a warmer climate has increased both net primary productivity (NPP) and the carbon sink in boreal forests. However, higher production and greener canopies may accompany changes in carbon allocation that favor foliage or fine roots over less decomposable woody biomass. Furthermore, tree core data throughout mid- and northern latitudes have revealed a divergence problem (DP), a weakening in tree ring responses to warming over the past half century that is receiving increasing attention, but remains poorly understood. Often, the same sites exhibit trend inconsistency phenomenon (TIP), namely positive, or no trends in growing season NDVI where negative trends in tree ring indexes are observed. Here we studied growth of two Norway spruce (Picea abies) stands in western Russia that exhibited both the DP and TIP but were subject to soil acidification and calcium depletion of differing timing and severity. Our results link the decline in radial growth starting in 1980 to a shift in carbon allocation from wood to roots driven by a combination of two factors: (a) soil acidification that depleted calcium and impaired root function and (b) earlier onset of the growing season that further taxed the root system. The latter change in phenology appears to act as a trigger at both sites to push trees into nutrient limitation as the demand for Ca increased with the longer growing season, thereby causing the shift in carbon allocation.

  8. Climate warming shifts carbon allocation from stemwood to roots in calcium-depleted spruce forests

    USGS Publications Warehouse

    Lapenis, Andrei Gennady; Lawrence, Gregory B.; Heim, Alexander; Zheng, Chengyang; Shortle, Walter

    2013-01-01

    Increased greening of northern forests, measured by the Normalized Difference Vegetation Index (NDVI), has been presented as evidence that a warmer climate has increased both net primary productivity (NPP) and the carbon sink in boreal forests. However, higher production and greener canopies may accompany changes in carbon allocation that favor foliage or fine roots over less decomposable woody biomass. Furthermore, tree core data throughout mid- and northern latitudes have revealed a divergence problem (DP), a weakening in tree ring responses to warming over the past half century that is receiving increasing attention, but remains poorly understood. Often, the same sites exhibit trend inconsistency phenomenon (TIP), namely positive, or no trends in growing season NDVI where negative trends in tree ring indexes are observed. Here we studied growth of two Norway spruce (Picea abies) stands in western Russia that exhibited both the DP and TIP but were subject to soil acidification and calcium depletion of differing timing and severity. Our results link the decline in radial growth starting in 1980 to a shift in carbon allocation from wood to roots driven by a combination of two factors: (a) soil acidification that depleted calcium and impaired root function and (b) earlier onset of the growing season that further taxed the root system. The latter change in phenology appears to act as a trigger at both sites to push trees into nutrient limitation as the demand for Ca increased with the longer growing season, thereby causing the shift in carbon allocation.

  9. Electrospinning of calcium carbonate fibers and their conversion to nanocrystalline hydroxyapatite.

    PubMed

    Holopainen, Jani; Santala, Eero; Heikkilä, Mikko; Ritala, Mikko

    2014-12-01

    Calcium carbonate (CaCO3) fibers were prepared by electrospinning followed by annealing. Solutions consisting of calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) and polyvinylpyrrolidone (PVP) dissolved in ethanol or 2-methoxyethanol were used for the fiber preparation. By varying the precursor concentrations in the electrospinning solutions CaCO3 fibers with average diameters from 140 to 290 nm were obtained. After calcination the fibers were identified as calcite by X-ray diffraction (XRD). The calcination process was studied in detail with high temperature X-ray diffraction (HTXRD) and thermogravimetric analysis (TGA). The initially weak fiber-to-substrate adhesion was improved by adding a strengthening CaCO3 layer by spin or dip coating Ca(NO3)2/PVP precursor solution on the CaCO3 fibers followed by annealing of the gel formed inside the fiber layer. The CaCO3 fibers were converted to nanocrystalline hydroxyapatite (HA) fibers by treatment in a dilute phosphate solution. The resulting hydroxyapatite had a plate-like crystal structure with resemblance to bone mineral. The calcium carbonate and hydroxyapatite fibers are interesting materials for bone scaffolds and bioactive coatings.

  10. Nucleation of calcium carbonate in presence of citric acid, DTPA, EDTA and pyromellitic acid.

    PubMed

    Westin, K-J; Rasmuson, A C

    2005-02-15

    The influence of four calcium complexing additives, i.e., citric acid (CIT), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA) and pyromellitic acid (PMA), and their concentration on the induction time of calcium carbonate nucleation has been studied. The experiments were performed by rapidly mixing a sodium carbonate solution and a calcium chloride solution of various concentrations. The induction time was obtained by recording the white light absorption of the solution. Chemical speciation was used to estimate the initial thermodynamic driving force of each experiment. The induction time was found to increase with additive concentration. The effect varies from one additive to another. CIT causes the greatest increase in induction time and PMA the least. Using classical nucleation theory the experimental data were evaluated in terms of the interfacial energy. In pure water a value of 37.8 mJ m(-2) was obtained, showing good agreement with other works. CIT, DTPA and EDTA caused a notable increase of the interfacial energy at a concentration of 0.5 mmol l(-1). PMA does not appear to have any effect at all on the interfacial energy. Different mechanisms for the influence of the additives on the measured induction time and on the estimated interfacial energy are discussed. PMID:15589542

  11. A Chemical Template for Synthesis of Molecular Sheets of Calcium Carbonate

    PubMed Central

    Rianasari, Ina; Benyettou, Farah; Sharma, Sudhir Kumar; Blanton, Thomas; Kirmizialtin, Serdal; Jagannathan, Ramesh

    2016-01-01

    Inspired by the discovery of graphene and its unique properties, we focused our research to develop a scheme to create nacre like lamellar structures of molecular sheets of CaCO3 interleaved with an organic material, namely carbon. We developed a facile, chemical template technique, using a formulation of poly(acrylic) acid (PAA) and calcium acetate to create lamellar stacks of single crystal sheets of CaCO3, with a nominal thickness of 17 Å, the same as a unit-cell dimension for calcite (c–axis = 17.062 Å), interleaved with amorphous carbon with a nominal thickness of 8 Å. The strong binding affinity between carboxylate anions and calcium cations in the formulation was used as a molecular template to guide CaCO3 crystallization. Computational modeling of the FTIR spectra showed good agreement with experimental data and confirmed that calcium ions are bridged between polymer chains, resulting in a net-like polymer structure. The process readily lends itself to explore the feasibility of creating molecular sheets of other important inorganic materials and potentially find applications in many fields such as super capacitors and “low k di-electric” systems. PMID:27145699

  12. A Chemical Template for Synthesis of Molecular Sheets of Calcium Carbonate.

    PubMed

    Rianasari, Ina; Benyettou, Farah; Sharma, Sudhir Kumar; Blanton, Thomas; Kirmizialtin, Serdal; Jagannathan, Ramesh

    2016-01-01

    Inspired by the discovery of graphene and its unique properties, we focused our research to develop a scheme to create nacre like lamellar structures of molecular sheets of CaCO3 interleaved with an organic material, namely carbon. We developed a facile, chemical template technique, using a formulation of poly(acrylic) acid (PAA) and calcium acetate to create lamellar stacks of single crystal sheets of CaCO3, with a nominal thickness of 17 Å, the same as a unit-cell dimension for calcite (c-axis = 17.062 Å), interleaved with amorphous carbon with a nominal thickness of 8 Å. The strong binding affinity between carboxylate anions and calcium cations in the formulation was used as a molecular template to guide CaCO3 crystallization. Computational modeling of the FTIR spectra showed good agreement with experimental data and confirmed that calcium ions are bridged between polymer chains, resulting in a net-like polymer structure. The process readily lends itself to explore the feasibility of creating molecular sheets of other important inorganic materials and potentially find applications in many fields such as super capacitors and "low k di-electric" systems. PMID:27145699

  13. A Chemical Template for Synthesis of Molecular Sheets of Calcium Carbonate

    NASA Astrophysics Data System (ADS)

    Rianasari, Ina; Benyettou, Farah; Sharma, Sudhir Kumar; Blanton, Thomas; Kirmizialtin, Serdal; Jagannathan, Ramesh

    2016-05-01

    Inspired by the discovery of graphene and its unique properties, we focused our research to develop a scheme to create nacre like lamellar structures of molecular sheets of CaCO3 interleaved with an organic material, namely carbon. We developed a facile, chemical template technique, using a formulation of poly(acrylic) acid (PAA) and calcium acetate to create lamellar stacks of single crystal sheets of CaCO3, with a nominal thickness of 17 Å, the same as a unit-cell dimension for calcite (c–axis = 17.062 Å), interleaved with amorphous carbon with a nominal thickness of 8 Å. The strong binding affinity between carboxylate anions and calcium cations in the formulation was used as a molecular template to guide CaCO3 crystallization. Computational modeling of the FTIR spectra showed good agreement with experimental data and confirmed that calcium ions are bridged between polymer chains, resulting in a net-like polymer structure. The process readily lends itself to explore the feasibility of creating molecular sheets of other important inorganic materials and potentially find applications in many fields such as super capacitors and “low k di-electric” systems.

  14. Profile storage of organic/inorganic carbon in soil: from forest to desert.

    PubMed

    Wang, Yugang; Li, Yan; Ye, Xuehua; Chu, Yu; Wang, Xinping

    2010-03-15

    Understanding the distribution of organic/inorganic carbon storage in soil profile is crucial for assessing regional, continental and global soil C stores and predicting the consequences of global change. However, little is known about the organic/inorganic carbon storages in deep soil layers at various landscapes. This study was conducted to determine the soil organic/inorganic carbon storage in soil profile of 0-3m at 5 sites of natural landscape from forest to desert. Landscapes are temperate forest, temperate grassland, temperate shrub-grassland, temperate shrub desert, and temperate desert. Root mass density and carbon contents at the profile were determined for each site. The results showed that considerable decrease in root biomass and soil organic carbon content at the soil profile of 0-3m when landscape varied from forest to desert along a precipitation gradient, while soil inorganic carbon content increased significantly along the precipitation gradient. Namely, for density of soil organic carbon: forest>grassland>shrub-grassland>shrub desert>desert; for density of soil inorganic carbon: forest, grasslandcarbon storage was found in 1-3m depth. For grassland and shrub-grassland, the contribution from 1-3m was mainly in the form of organic carbon, while for shrub desert and desert the contribution from this depth was mainly in the form of inorganic carbon. The comparison of soil C storage between top 0-1m and 1-3m showed that the using top 1m of soil profile to estimate soil carbon storages would considerably underestimate soil carbon storage. This is especially true for organic soil carbon at grassland region, and for soil inorganic carbon at desert region.

  15. Microscopic Evidence for a dense liquid phase of calcium carbonate (Invited)

    NASA Astrophysics Data System (ADS)

    Wallace, A. F.; Hedges, L.; Fernandez-Martinez, A.; Raiteri, P.; Gale, J. D.; Waychunas, G.; Whitelam, S.; Banfield, J. F.; De Yoreo, J. J.

    2013-12-01

    In the classical sense, minerals are presumed to nucleate directly from solution by overcoming a size-dependent free energy barrier that scales as the ratio of the macroscopic mineral-water interfacial tension cubed to the square of the thermodynamic supersaturation. However, experimental observations of the early stages of calcium carbonate mineralization demonstrate that under certain conditions formation of the crystalline polymorphs is preceded by the apparently spontaneous appearance of nanoscopic clusters that aggregate to produce metastable amorphous phases. This aggregation-based pathway is seemingly at odds with classical expectations. This research (Wallace et al., in press, Science) uses computational approaches to characterize the thermodynamic and dynamic properties of hydrated calcium carbonate cluster species, which are thus far only loosely constrained by experimental investigations. Replica exchange molecular dynamics simulations are employed to probe the initial formation of the clusters and lattice gas simulations are used to explore the general behavior of clusters at the onset of mineralization. The results suggest the growth of carbonate clusters may indeed proceed in the absence of any significant thermodynamic barrier. Moreover, the dynamical properties of the clusters are consistent with those of a dense liquid phase. Coalescence and dehydration of the nanoscale droplets result in the formation of a phase whose structure is consistent with that of amorphous calcium carbonate. These findings indicate that a spontaneous liquid-liquid phase separation may occur within the range of supersaturations spanned by natural waters. The coexistence of the dense and dilute liquid phases is described by a liquid-liquid binodal that may express a lower critical point near ambient temperature. Though liquid-liquid separation in simulations of the CaCO3-H2O system is an unexpected result, it suggests a means of generating nano- and mesoscopic phases

  16. Fabrication and cellular biocompatibility of porous carbonated biphasic calcium phosphate ceramics with a nanostructure.

    PubMed

    Li, Bo; Chen, Xuening; Guo, Bo; Wang, Xinlong; Fan, Hongsong; Zhang, Xingdong

    2009-01-01

    Microwave heating was applied to fabricate interconnective porous structured bodies by foaming as-synthesized calcium-deficient hydroxyapatite (Ca-deficient HA) precipitate containing H(2)O(2). The porous bodies were sintered by a microwave process with activated carbon as the embedding material to prepare nano- and submicron-structured ceramics. By comparison, conventional sintering was used to produce microstructured ceramics. The precursor particles and bulk ceramics were characterized by transmission electron microscopy (TEM), dynamic light scattering, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR) and mechanical testing. TEM micrographs and assessment of the size distribution showed that the needle-like precursor particles are on the nanoscale. SEM observation indicated that the ceramics formed by microwave sintering presented a structure of interconnective pores, with average grain sizes of approximately 86 and approximately 167nm. XRD patterns and FTIR spectra confirmed the presence of carbonated biphasic calcium phosphate (BCP), and the mechanical tests showed that the ceramics formed by microwave sintering had a compressive strength comparable to that obtained by conventional methods. Rat osteoblasts were cultured on the three kinds of BCP ceramics to evaluate their biocompatibility. Compared with the microscale group formed by conventional sintering, MTT assay and ALP assay showed that nanophase scaffolds promoted cell proliferation and differentiation respectively, and SEM observation showed that the nanoscale group clearly promoted cell adhesion. The results from this study suggest that porous carbonated biphasic calcium phosphate ceramics with a nanostructure promote osteoblast adhesion, proliferation and differentiation. In conclusion, porous carbonated BCP ceramics with a nanostructure are simple and quick to prepare using microwaves and compared with those produced by conventional

  17. Capacitive energy storage in nanostructured carbon-electrolyte systems.

    PubMed

    Simon, P; Gogotsi, Y

    2013-05-21

    Securing our energy future is the most important problem that humanity faces in this century. Burning fossil fuels is not sustainable, and wide use of renewable energy sources will require a drastically increased ability to store electrical energy. In the move toward an electrical economy, chemical (batteries) and capacitive energy storage (electrochemical capacitors or supercapacitors) devices are expected to play an important role. This Account summarizes research in the field of electrochemical capacitors conducted over the past decade. Overall, the combination of the right electrode materials with a proper electrolyte can successfully increase both the energy stored by the device and its power, but no perfect active material exists and no electrolyte suits every material and every performance goal. However, today, many materials are available, including porous activated, carbide-derived, and templated carbons with high surface areas and porosities that range from subnanometer to just a few nanometers. If the pore size is matched with the electrolyte ion size, those materials can provide high energy density. Exohedral nanoparticles, such as carbon nanotubes and onion-like carbon