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Sample records for supercritical co2 fluid

  1. Supercritical CO2 fluid radiochromatography system used to purify [11C]toluene for PET.

    PubMed

    Muller, Ryan D; Ferrieri, Richard A; Gerasimov, Madina; Garza, Victor

    2002-04-01

    Abuse of inhalants in today's society has become such a widespread problem among today's adolescents that in many parts of the world their use exceeds that of many other illicit drugs or alcohol. Even so, little is known how such inhalants affect brain function to an extent that can lead to an abuse liability. While methodologies exist for radiolabeling certain inhalants of interest with short-lived positron emitting radioisotopes that would allow their investigation in human subjects using positron emission tomography (PET), the purification methodologies necessary to separate these volatile substances from the organic starting materials have not been developed. We've adapted supercritical fluid technology to this specific PET application by building a preparative-scale supercritical CO2 fluid radiochromatograph, and applied it to the purification of [11C]toluene. We've demonstrated that [11C]toluene can be separated from the starting materials using a conventional C18 HPLC column and pure supercritical CO2 fluid as the mobile phase operating at 2000 psi and 40 degrees C. We've also shown that the purified radiotracer can be quantitatively captured on Tenax GR, a solid support material, as it exits the supercritical fluid stream, thus allowing for later desorption into a 1.5% cyclodextrin solution that is suitable for human injection, or into a breathing tube for direct inhalation. PMID:11929706

  2. Insights into Silicate Carbonation Processes in Water-Bearing Supercritical CO2 Fluids

    SciTech Connect

    Miller, Quin RS; Thompson, Christopher J.; Loring, John S.; Windisch, Charles F.; Bowden, Mark E.; Hoyt, David W.; Hu, Jian Z.; Arey, Bruce W.; Rosso, Kevin M.; Schaef, Herbert T.

    2013-07-01

    Long-term geologic storage of carbon dioxide (CO2) is considered an integral part to moderating CO2 concentrations in the atmosphere and subsequently minimizing effects of global climate change. Although subsurface injection of CO2 is common place in certain industries, deployment at the scale required for emission reduction is unprecedented and therefore requires a high degree of predictability. Accurately modeling geochemical processes in the subsurface requires experimental derived data for mineral reactions occurring between the CO2, water, and rocks. Most work in this area has focused on aqueous-dominated systems in which dissolved CO2 reacts to form crystalline carbonate minerals. Comparatively little laboratory research has been conducted on reactions occurring between minerals in the host rock and the wet supercritical fluid phase. In this work, we studied the carbonation of wollastonite [CaSiO3] exposed to variably hydrated supercritical CO2 (scCO2) at a range of temperatures (50, 55 and 70 °C) and pressures (90,120 and 160 bar) that simulate conditions in geologic repositories. Mineral transformation reactions were followed by three novel in situ high pressure techniques, including x-ray diffraction that tracked the rate and extents of wollastonite conversion to calcite. Increased dissolved water concentrations in the supercritical CO2 resulted in increased silicate carbonation approaching ~50 wt. %. Development of thin water films on the mineral surface were directly observed with infrared spectroscopy and determined to be critical for facilitating carbonation processes. Even in extreme low water conditions, magic angle spinning nuclear magnetic resonance detected formation of Q3 [Si(OSi)3OH] and Q4 [Si(OSi)4] amorphous silica species. Unlike the thick (<10 μm) passivating silica layers observed in the fully water saturated scCO2 experiments, images obtained from a focused ion beam sectioned sample indicted these coatings were chemically wollastonite

  3. Two-Dimensional Nanoparticle Cluster Formation in Supercritical Fluid CO2.

    PubMed

    Wang, Joanna S; Wai, Chien M; Brown, Gail J; Apt, Scott D

    2016-05-10

    Supercritical fluid carbon dioxide (sc-CO2) is capable of depositing nanoparticles in small structures of silicon substrates because of its gas-like penetration, liquid-like solvation abilities, and near-zero surface tension. In nanometer-sized shallow wells on silicon surface, formation of two-dimensional (2D) monolayer metal nanoparticle (NP) clusters can be achieved using the sc-CO2 deposition method. Nanoparticles tend to fill nanostructured holes first, and then, if sufficient nanoparticles are available, they will continue to cover the flat areas nearby, unless defects or other surface imperfections are available. In addition, SEM images of two-dimensional gold (Au) nanoparticle clusters formed on a flat silicon surface with two to a dozen or more of the nanoparticles are provided to illustrate the patterns of nanoparticle cluster formation in sc-CO2. PMID:27088712

  4. Supercritical fluid behavior at nanoscale interfaces: implications for CO2 sequestration in geologic formations

    SciTech Connect

    Cole, David R; Chialvo, Ariel A; Rother, Gernot; Vlcek, L.; Cummings, Peter T

    2010-01-01

    Injection of CO2 into subsurface geologic formations has been identified as a key strategy for mitigating the impact of anthropogenic emissions of CO2. A key aspect of this process is the prevention of leakage from the host formation by an effective cap or seal rock which has low porosity and permeability characteristics. Shales comprise the majority of cap rocks encountered in subsurface injection sites with pore sizes typically less than 100 nm and whose surface chemistries are dominated by quartz (SiO2) and clays. We report the behavior of pure CO2 interacting with simple substrates, i.e. SiO2 and mica, that act as proxies for more complex mineralogical systems. Modeling of small-angle neutron scattering (SANS) data taken from CO2- silica aerogel (95% porosity; 6 nm pores) interactions indicates the presence of fluid depletion for conditions above the critical density. A theoretical framework, i.e. integral equation approximation (IEA), is presented that describes the fundamental behavior of near-critical adsorption onto a non-confining substrate that is consistent with SANS experimental results. Structural and dynamic behavior for supercritical CO2 interaction in K-mica slit pores was assessed by classical molecular dynamics (CMD). These results indicate the development of distinct layers of CO2 within slit pores, reduced mobility by one to two orders of magnitudes compared to bulk CO2 depending on pore size and formation of bonds between CO2 oxygens and H from mica hydroxyls. Analysis of simple, well-characterized fluid-substrate systems can provide details on the thermodynamic, structural and dynamic properties of CO2 at conditions relevant to sequestration.

  5. Silicate Carbonation Processes in Water-Bearing Supercritical CO2 Fluids: Implications for Geologic Carbon Sequestration

    NASA Astrophysics Data System (ADS)

    Miller, Q. R.; Schaef, T.; Thompson, C.; Loring, J. S.; Windisch, C. F.; Bowden, M. E.; Arey, B. W.; McGrail, P.

    2012-12-01

    Global climate change is viewed by many as an anthropogenic phenomenon that could be mitigated through a combination of conservation efforts, alternative energy sources, and the development of technologies capable of reducing carbon dioxide (CO2) emissions. Continued increases of atmospheric CO2 concentrations are projected over the next decade, due to developing nations and growing populations. One economically favorable option for managing CO2 involves subsurface storage in deep basalt formations. The silicate minerals and glassy mesostasis basalt components act as metal cation sources, reacting with the CO2 to form carbonate minerals. Most prior work on mineral reactivity in geologic carbon sequestration settings involves only aqueous dominated reactions. However, in most sequestration scenarios, injected CO2 will reside as a buoyant fluid in contact with the sealing formation (caprock) and slowly become water bearing. Comparatively little laboratory research has been conducted on reactions occurring between minerals in the host rock and the wet scCO2. In this work, we studied the carbonation of wollastonite [CaSiO3] exposed to variably wet supercritical CO2 (scCO2) at a range of temperatures (50, 55 and 70 °C) and pressures (90,120 and 160 bar) in order to gain insight into reaction processes. Mineral transformation reactions were followed by two novel in situ high pressure techniques, including x-ray diffraction that tracked the rate and extents of wollastonite conversion to calcite. Increased dissolved water concentrations in the scCO2 resulted in increased carbonation approaching ~50 wt. %. Development of thin water films on the mineral surface were directly observed with infrared (IR) spectroscopy and indirectly with 18O isotopic labeling techniques (Raman spectroscopy). The thin water films were determined to be critical for facilitating carbonation processes in wet scCO2. Even in extreme low water conditions, the IR technique detected the formation of

  6. Impacts of Organic Ligands on Forsterite Reactivity in Supercritical CO2 Fluids

    SciTech Connect

    Miller, Quin R.; Kaszuba, John; Schaef, Herbert T.; Bowden, Mark E.; McGrail, B. Peter

    2015-04-07

    Subsurface injection of CO2 for enhanced hydrocarbon recovery, hydraulic fracturing of unconventional reservoirs, and geologic carbon sequestration produces a complex geochemical setting in which CO2-dominated fluids containing dissolved water and organic compounds interact with rocks and minerals. The details of these reactions are relatively unknown and benefit from additional experimentally derived data. In this study, we utilized an in situ X-ray diffraction technique to examine the carbonation reactions of forsterite (Mg2SiO4) during exposure to supercritical CO2 (scCO2) that had been equilibrated with aqueous solutions of acetate, oxalate, malonate, or citrate at 50 °C and 90 bar. The organics affected the relative abundances of the crystalline reaction products, nesquehonite (MgCO3·3H2O) and magnesite (MgCO3), likely due to enhanced dehydration of the Mg2+ cations by the organic ligands. These results also indicate that the scCO2 solvated and transported the organic ligands to the forsterite surface. This phenomenon has profound implications for mineral transformations and mass transfer in the upper crust.

  7. Impacts of organic ligands on forsterite reactivity in supercritical CO2 fluids.

    PubMed

    Miller, Quin R S; Kaszuba, John P; Schaef, Herbert T; Bowden, Mark E; McGrail, Bernard P

    2015-04-01

    Subsurface injection of CO2 for enhanced hydrocarbon recovery, hydraulic fracturing of unconventional reservoirs, and geologic carbon sequestration produces a complex geochemical setting in which CO2-dominated fluids containing dissolved water and organic compounds interact with rocks and minerals. The details of these reactions are relatively unknown and benefit from additional experimentally derived data. In this study, we utilized an in situ X-ray diffraction technique to examine the carbonation reactions of forsterite (Mg2SiO4) during exposure to supercritical CO2 (scCO2) that had been equilibrated with aqueous solutions of acetate, oxalate, malonate, or citrate at 50 °C and 90 bar. The organics affected the relative abundances of the crystalline reaction products, nesquehonite (MgCO3 · 3H2O) and magnesite (MgCO3), likely due to enhanced dehydration of the Mg(2+) cations by the organic ligands. These results also indicate that the scCO2 solvated and transported the organic ligands to the forsterite surface. This phenomenon has profound implications for mineral transformations and mass transfer in the upper crust. PMID:25807011

  8. Calcite solubility in supercritical CO 2H 2O fluids

    NASA Astrophysics Data System (ADS)

    Fein, Jeremy B.; Walther, John V.

    1987-06-01

    An extraction-quench apparatus was used to measure calcite solubilities in supercritical CO 2H 2O mixtures. Experiments were conducted at 1 kbar and 2 kbar, between 240°C and 620°C and from XCO 2 = .02 toXCO 2 = .15 in order to determine the solubility behavior as a function of pressure, temperature and CO 2 content. The results indicate that calcite solubilities under these conditions behave similarly to previously investigated calcite solubilities at lower pressures and temperatures (SHARP and Kennedy, 1965). At constant XCO 2, the solubility increases with increasing pressure, but it decreases with increasing temperature. When the temperature and pressure are constant, the calcite solubility rises with increasing XCO 2 to a maximum value at XCO 2 between 0.02 and 0.05. For higher CO 2 contents, up to XCO 2 = .15, the calcite solubility decreases, probably due to the decrease of H 2O activities to values significantly below unity. The solubility behavior can be successfully modeled by making the assumption that Ca ++ is the dominant calcium species and that the carbon-bearing species are CO 2(aq) and HCO -3. Since for these dilute H 2OCO 2 fluids, all activity coefficients can be assumed to not differ significantly from unity, ionization constants for the reaction H 2O + CO 2(aq) H + + HCO -3 can be calculated at 1 and 2 kbar between 250°C and 550°C. These calculated values are in good agreement with the low temperature determinations of the ionization constants for this reaction determined by Read (1975). Values of the molal Gibbs free energy of CO 2(aq) obtained in our study exhibit a much greater positive departure from ideality than those calculated with the modified Redlich-Kwong equations of either Flowers (1979) or Kerrick and Jacobs (1981) for dilute CO 2 aqueous solutions.

  9. Shale Micromodel Experiments: Fluid Flow and Mobilization using Supercritical CO2

    NASA Astrophysics Data System (ADS)

    Porter, M. L.; Carey, J. W.; Viswanathan, H.

    2014-12-01

    In recent years, use of engineered micromodels to investigate pore-scale fluid flow and transport phenomena to better understand and model field-scale observables has steadily increased. Micromodels are thin porous structures in which flow is restricted to two-dimensions and have become common since they are effective, relatively inexpensive tools for visualizing and quantifying complex flow phenomena. We describe a unique micromodel experimental system recently developed at Los Alamos National Laboratory (LANL). The system consists of a pressure chamber, which allows us to conduct experiments at geologic conditions. The maximum working pressure and temperature is 1500 psig and 80° C, respectively, allowing for supercritical carbon dioxide (scCO2) to be used as a working fluid. Additionally, we have developed micromodels fabricated in geomaterials (e.g., shale and Portland cement), whereas typical micromodels are fabricated in engineered materials such as glass or silicon. The use of geomaterial micromodels allows us to better represent the fluid-rock interactions including wetting angles and chemical reactivity at conditions representative of natural subsurface environments. In this work, we present experimental results in simple fracture systems (e.g., straight channels, pore doublets) with applications to hydrocarbon mobility in hydraulically fractured shale. We use both shale and glass micromodels, allowing for a detailed comparison between flow phenomena in different materials. In the straight channel micromodels, we investigate interfacial velocities and compare the results with theoretical models. In the pore doublet micromodels, we investigate mobilization of oil blobs and contrast the effectiveness of water and scCO2 in the extraction of hydrocarbon from fracture networks. Next, we present experimental results in complex fracture network patterns derived from 3D x-ray tomography images of actual fractures created in shale rock cores. We discuss

  10. Modeling of mass transfer of Phospholipids in separation process with supercritical CO2 fluid by RBF artificial neural networks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An artificial Radial Basis Function (RBF) neural network model was developed for the prediction of mass transfer of the phospholipids from canola meal in supercritical CO2 fluid. The RBF kind of artificial neural networks (ANN) with orthogonal least squares (OLS) learning algorithm were used for mod...

  11. Viability and adaptation potential of indigenous microorganisms from natural gas field fluids in high pressure incubations with supercritical CO2.

    PubMed

    Frerichs, Janin; Rakoczy, Jana; Ostertag-Henning, Christian; Krüger, Martin

    2014-01-21

    Carbon Capture and Storage (CCS) is currently under debate as large-scale solution to globally reduce emissions of the greenhouse gas CO2. Depleted gas or oil reservoirs and saline aquifers are considered as suitable reservoirs providing sufficient storage capacity. We investigated the influence of high CO2 concentrations on the indigenous bacterial population in the saline formation fluids of a natural gas field. Bacterial community changes were closely examined at elevated CO2 concentrations under near in situ pressures and temperatures. Conditions in the high pressure reactor systems simulated reservoir fluids i) close to the CO2 injection point, i.e. saturated with CO2, and ii) at the outer boundaries of the CO2 dissolution gradient. During the incubations with CO2, total cell numbers remained relatively stable, but no microbial sulfate reduction activity was detected. After CO2 release and subsequent transfer of the fluids, an actively sulfate-respiring community was re-established. The predominance of spore-forming Clostridiales provided evidence for the resilience of this taxon against the bactericidal effects of supercritical (sc)CO2. To ensure the long-term safety and injectivity, the viability of fermentative and sulfate-reducing bacteria has to be considered in the selection, design, and operation of CCS sites. PMID:24320192

  12. Natural wax constituents of a supercritical fluid CO(2) extract from quince (Cydonia oblonga Mill.) pomace.

    PubMed

    Lorenz, Peter; Berger, Melanie; Bertrams, Julia; Wende, Kristian; Wenzel, Kristin; Lindequist, Ulrike; Meyer, Ulrich; Stintzing, Florian C

    2008-05-01

    The chemical constituents of a lipophilic extract from quince (Cydonia oblonga Mill.), obtained by supercritical fluid CO(2) extraction of the dried fruit pomace were investigated. Solvent partition of quince wax with n-hexane or acetone yielded an insoluble (crystalline) and a soluble (oily) fraction. Both fractions were analyzed separately using gas chromatography/mass spectrometry (GC/MS). The insoluble fraction consisted of saturated n-aldehydes, n-alcohols and free n-alkanoic acids of carbon chain lengths between 22 and 32, with carbon chain lengths of 26 and 28 dominating. Also odd-numbered unbranched hydrocarbons, mainly C27, C29 and C31, were detected particularly in the acetone-insoluble fraction (total, 15.8%). By means of vacuum liquid chromatography, triterpenoic acids were separated from the hexane-insoluble matter and identified as a mixture of ursolic, oleanolic and betulinic acids. The major constituents of the hexane-soluble fraction were glycerides of linoleic [Δ(9,12), 18:2] and oleic [Δ(9), 18:1] acids, accompanied by free linoleic, oleic and palmitic acids (C16). Moreover β-sitosterol, Δ(5)-avenasterol as well as trace amounts of other sterols were assigned. Finally the carotenoids phytoene and phytofluene were identified and quantified by UV/vis and high-performance liquid chromatography/MS techniques, yielding 1.0 and 0.3% of the quince wax, respectively. It is anticipated that the complex of lipid constituents from quince wax may exert interesting biological activities, the elucidation of which awaits further studies. PMID:18418588

  13. Reducing operation current of Ni-doped silicon oxide resistance random access memory by supercritical CO2 fluid treatment

    NASA Astrophysics Data System (ADS)

    Chang, Kuan-Chang; Tsai, Tsung-Ming; Chang, Ting-Chang; Syu, Yong-En; Wang, Chia-C.; Chuang, Siang-Lan; Li, Cheng-Hua; Gan, Der-Shin; Sze, Simon M.

    2011-12-01

    In the study, we reduced the operation current of resistance random access memory (RRAM) by supercritical CO2 (SCCO2) fluids treatment. The power consumption and joule heating degradation of RRAM device can be improved greatly by SCCO2 treatment. The defect of nickel-doped silicon oxide (Ni:SiOx) was passivated effectively by the supercritical fluid technology. The current conduction of high resistant state in post-treated Ni:SiOx film was transferred to Schottky emission from Frenkel-Pool due to the passivation effect. Additionally, we can demonstrate the passivation mechanism of SCCO2 for Ni:SiOx by material analyses of x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy.

  14. Diameter-sensitive biocompatibility of anodic TiO2 nanotubes treated with supercritical CO2 fluid

    PubMed Central

    2013-01-01

    This work reports on the diameter-sensitive biocompatibility of anodic TiO2 nanotubes with different nanotube diameters grown by a self-ordering process and subsequently treated with supercritical CO2 (ScCO2) fluid. We find that highly hydrophilic as-grown TiO2 nanotubes become hydrophobic after the ScCO2 treatment but can effectively recover their surface wettability under UV light irradiation as a result of photo-oxidation of C-H functional groups formed on the nanotube surface. It is demonstrated that human fibroblast cells show more obvious diameter-specific behavior on the ScCO2-treated TiO2 nanotubes than on the as-grown ones in the range of diameters of 15 to 100 nm. This result can be attributed to the removal of disordered Ti(OH)4 precipitates from the nanotube surface by the ScCO2 fluid, thus resulting in purer nanotube topography and stronger diameter dependence of cell activity. Furthermore, for the smallest diameter of 15 nm, ScCO2-treated TiO2 nanotubes reveal higher biocompatibility than the as-grown sample. PMID:23547743

  15. Electrodeposition from supercritical fluids.

    PubMed

    Bartlett, P N; Cook, D A; George, M W; Hector, A L; Ke, J; Levason, W; Reid, G; Smith, D C; Zhang, W

    2014-05-28

    Recent studies have shown that it is possible to electrodeposit a range of materials, such as Cu, Ag and Ge, from various supercritical fluids, including hydrofluorocarbons and mixtures of CO2 with suitable co-solvents. In this perspective we discuss the relatively new field of electrodeposition from supercritical fluids. The perspective focuses on some of the underlying physical chemistry and covers both practical and scientific aspects of electrodeposition from supercritical fluids. We also discuss possible applications for supercritical fluid electrodeposition and suggest some key developments that are required to take the field to the next stage. PMID:24469309

  16. Heat Transfer and Fluid Transport of Supercritical CO2 in Enhanced Geothermal System with Local Thermal Non-equilibrium Model

    DOE PAGESBeta

    Zhang, Le; Luo, Feng; Xu, Ruina; Jiang, Peixue; Liu, Huihai

    2014-12-31

    The heat transfer and fluid transport of supercritical CO2 in enhanced geothermal system (EGS) is studied numerically with local thermal non-equilibrium model, which accounts for the temperature difference between solid matrix and fluid components in porous media and uses two energy equations to describe heat transfer in the solid matrix and in the fluid, respectively. As compared with the previous results of our research group, the effect of local thermal non-equilibrium mainly depends on the volumetric heat transfer coefficient ah, which has a significant effect on the production temperature at reservoir outlet and thermal breakthrough time. The uniformity of volumetricmore » heat transfer coefficient ah has little influence on the thermal breakthrough time, but the temperature difference become more obvious with time after thermal breakthrough with this simulation model. The thermal breakthrough time reduces and the effect of local thermal non-equilibrium becomes significant with decreasing ah.« less

  17. Inhibitory effect of rape pollen supercritical CO2 fluid extract against testosterone-induced benign prostatic hyperplasia in rats

    PubMed Central

    YANG, BI-CHENG; JIN, LI-LI; YANG, YI-FANG; LI, KUN; PENG, DAN-MING

    2014-01-01

    Benign prostatic hyperplasia (BPH) can lead to lower urinary tract symptoms. Rape pollen is an apicultural product that is composed of nutritionally valuable and biologically active substances. The aim of the present study was to investigate the protective effect of rape pollen supercritical CO2 fluid extract (SFE-CO2) in BPH development using a testosterone-induced BPH rat model. BPH was induced in the experimental groups by daily subcutaneous injections of testosterone for a period of 30 days. Rape pollen SFE-CO2 was administered daily by oral gavage concurrently with the testosterone injections. Animals were sacrificed at the scheduled termination and the prostates were weighed and subjected to histopathological examination. Testosterone, dihydrotestosterone (DHT), 5α-reductase and cyclooxygenase-2 (COX-2) levels were also measured. BPH-induced animals exhibited an increase in prostate weight with increased testosterone, DHT, 5α-reductase and COX-2 expression levels. However, rape pollen SFE-CO2 treatment resulted in significant reductions in the prostate index and testosterone, DHT, 5α-reductase and COX-2 levels compared with those in BPH-induced animals. Histopathological examination also demonstrated that rape pollen SFE-CO2 treatment suppressed testosterone-induced BPH. These observations indicate that rape pollen SFE-CO2 inhibits the development of BPH in rats and these effects are closely associated with reductions in DHT, 5α-reductase and COX-2 levels. Therefore, the results of the present study clearly indicate that rape pollen SFE-CO2 extract may be a useful agent in BPH treatment. PMID:24944593

  18. Fundamental study of CO2-H2O-mineral interactions for carbon sequestration, with emphasis on the nature of the supercritical fluid-mineral interface.

    SciTech Connect

    Bryan, Charles R.; Dewers, Thomas A.; Heath, Jason E.; Wang, Yifeng; Matteo, Edward N.; Meserole, Stephen P.; Tallant, David Robert

    2013-09-01

    In the supercritical CO2-water-mineral systems relevant to subsurface CO2 sequestration, interfacial processes at the supercritical fluid-mineral interface will strongly affect core- and reservoir-scale hydrologic properties. Experimental and theoretical studies have shown that water films will form on mineral surfaces in supercritical CO2, but will be thinner than those that form in vadose zone environments at any given matric potential. The theoretical model presented here allows assessment of water saturation as a function of matric potential, a critical step for evaluating relative permeabilities the CO2 sequestration environment. The experimental water adsorption studies, using Quartz Crystal Microbalance and Fourier Transform Infrared Spectroscopy methods, confirm the major conclusions of the adsorption/condensation model. Additional data provided by the FTIR study is that CO2 intercalation into clays, if it occurs, does not involve carbonate or bicarbonate formation, or significant restriction of CO2 mobility. We have shown that the water film that forms in supercritical CO2 is reactive with common rock-forming minerals, including albite, orthoclase, labradorite, and muscovite. The experimental data indicate that reactivity is a function of water film thickness; at an activity of water of 0.9, the greatest extent of reaction in scCO2 occurred in areas (step edges, surface pits) where capillary condensation thickened the water films. This suggests that dissolution/precipitation reactions may occur preferentially in small pores and pore throats, where it may have a disproportionately large effect on rock hydrologic properties. Finally, a theoretical model is presented here that describes the formation and movement of CO2 ganglia in porous media, allowing assessment of the effect of pore size and structural heterogeneity on capillary trapping efficiency. The model results also suggest possible engineering approaches for optimizing trapping capacity and for

  19. HPLC Method for the Simultaneous Determination of Ten Annonaceous Acetogenins after Supercritical Fluid CO2 Extraction

    PubMed Central

    Yang, Haijun; Zhang, Ning; Zeng, Qingqi; Yu, Qiping; Ke, Shihuai; Li, Xiang

    2010-01-01

    Annonaceous acetogenins (ACGs) isolated from Annonaceae plants exhibited a broad range of biological bioactivities such as cytotoxic, antitumoral, antiparasitic, pesticidal and immunosuppresive activities. However, their structures were liable to change at more than 60°C and their extraction yields were low using traditional organic solvent extraction. In the present study, all samples from Annona genus plant seeds were extracted by supercritical carbon dioxide under optimized conditions and a high-performance liquid chromatography (HPLC) method was established for simultaneously determining ten ACGs. All of the ten compounds were simultaneously separated on reversed-phase C18 column (250 mm × 4.6 mm, 5 μm) with the column temperature at 30°C. The mobile phase was composed of (A) methanol and (B) distilled water, the flow rate was 1.0 ml/min and the detection wavelength was set at 220 nm. All calibration curves showed good linear regression (γ>0.9995) within the test range. The established method showed good precision and accuracy with overall intra-day and inter-day variations of 0.99-2.56% and 1.93-3.65%, respectively, and overall recoveries of 95.16-105.01% for the ten compounds analyzed. The established method can be applied to evaluate the intrinsic quality of Annonaceae plant seeds. The determination results recover the content-variation regularities of various ACGs in different species, which are helpful to choose the good-quality Annonaceae plant seeds for anticancer lead compound discovery. PMID:23675194

  20. ANALYSIS OF FLAVOR COMPOUNDS FROM MICROWAVE POPCORN USING SUPERCRITICAL FLUID CO2 FOLLOWED BY DYNAMIC/STATIC HEADSPACE TECHNIQUES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dynamic headspace purge (DHP) analysis was used to observe volatile compounds from freshly popped commercial flavored and non-flavored microwave popcorn. The obtained results were compared with supercritical fluid extraction (SFE) followed by DHP. The sensitivity of the latter method (SFE-DHP), in...

  1. Pulsed laser ablation plasmas generated in CO2 under high-pressure conditions up to supercritical fluid

    NASA Astrophysics Data System (ADS)

    Kato, Toru; Stauss, Sven; Kato, Satoshi; Urabe, Keiichiro; Baba, Motoyoshi; Suemoto, Tohru; Terashima, Kazuo

    2012-11-01

    Pulsed laser ablation of solids in supercritical media has a large potential for nanomaterials fabrication. We investigated plasmas generated by pulsed laser ablation of Ni targets in CO2 at pressures ranging from 0.1 to 16 MPa at 304.5 K. Plasma species were characterized by optical emission spectroscopy, and the evolution of cavitation bubbles and shockwaves were observed by time-resolved shadowgraph imaging. Ni and O atomic emissions decreased with increasing gas pressure; however, near the critical point the intensities reached local maxima, probably due to the enhancement of the plasma excitation and effective quenching resulting from the large density fluctuation.

  2. Reducing Oyster-Associated Bacteria Levels Using Supercritical Fluid CO2 as an Agent of Warm Pasteurization

    PubMed Central

    Meujo, Damaris A.F.; Kevin, Dion; Peng, Jiangnan; Bowling, John J.; Liu, Jianping; Hamann, Mark T.

    2010-01-01

    An innovative approach to Post-Harvest Processing (PHP) of oysters is introduced focusing on the effects of supercritical carbon dioxide (scCO2) on bacterial contaminants trapped in the digestive system of oysters. Oysters were exposed to scCO2 under two conditions: (1) 100 bar and 37 °C for 30 minutes and (2) 172 bar and 60 °C for 60 minutes. Using FDA standard guidelines for food analysis, variations in the Aerobic Plate Count (APC) was assessed. It was established that exposing oysters to CO2 at 100 bar and 37 °C for 30 minutes and at 172 bar and 60°C for 60 minutes induced 2-log and 3-log reductions in the APC respectively. The decrease in the microbial load as a result of treatment with scCO2 was found to be significant (P=0.002). A release of adductor muscles from the shell was noted in oysters treated at 172 bar and 60 °C for 60 minutes; this was not the case for oysters treated at 100 bar and 37 °C for 30 minutes. A blind study allowing sensory analysis of treated vs. untreated oysters was also completed and no significant change in the physical appearance, smell, or texture was recorded. In this paper, we also report the effect of scCO2 on several bacterial isolates, including a referenced ATCC strain of a non pathogenic Vibrio (V. fisherii) as well as several other bacterial isolates cultured from oyster’ tissues and found to share biochemical features common to pathogenic Vibrio strains. A complete inactivation (minimum 7-log reduction) was achieved with these latter bacterial isolates. A 6-log reduction was observed with V. fisherii. PMID:20022650

  3. Microbial Growth under Supercritical CO2

    PubMed Central

    Peet, Kyle C.; Freedman, Adam J. E.; Hernandez, Hector H.; Britto, Vanya; Boreham, Chris; Ajo-Franklin, Jonathan B.

    2015-01-01

    Growth of microorganisms in environments containing CO2 above its critical point is unexpected due to a combination of deleterious effects, including cytoplasmic acidification and membrane destabilization. Thus, supercritical CO2 (scCO2) is generally regarded as a sterilizing agent. We report isolation of bacteria from three sites targeted for geologic carbon dioxide sequestration (GCS) that are capable of growth in pressurized bioreactors containing scCO2. Analysis of 16S rRNA genes from scCO2 enrichment cultures revealed microbial assemblages of varied complexity, including representatives of the genus Bacillus. Propagation of enrichment cultures under scCO2 headspace led to isolation of six strains corresponding to Bacillus cereus, Bacillus subterraneus, Bacillus amyloliquefaciens, Bacillus safensis, and Bacillus megaterium. Isolates are spore-forming, facultative anaerobes and capable of germination and growth under an scCO2 headspace. In addition to these isolates, several Bacillus type strains grew under scCO2, suggesting that this may be a shared feature of spore-forming Bacillus spp. Our results provide direct evidence of microbial activity at the interface between scCO2 and an aqueous phase. Since microbial activity can influence the key mechanisms for permanent storage of sequestered CO2 (i.e., structural, residual, solubility, and mineral trapping), our work suggests that during GCS microorganisms may grow and catalyze biological reactions that influence the fate and transport of CO2 in the deep subsurface. PMID:25681188

  4. Final Report: Development of a Chemical Model to Predict the Interactions between Supercritical CO2, Fluid and Rock in EGS Reservoirs

    SciTech Connect

    McPherson, Brian J.; Pan, Feng

    2014-09-24

    This report summarizes development of a coupled-process reservoir model for simulating enhanced geothermal systems (EGS) that utilize supercritical carbon dioxide as a working fluid. Specifically, the project team developed an advanced chemical kinetic model for evaluating important processes in EGS reservoirs, such as mineral precipitation and dissolution at elevated temperature and pressure, and for evaluating potential impacts on EGS surface facilities by related chemical processes. We assembled a new database for better-calibrated simulation of water/brine/ rock/CO2 interactions in EGS reservoirs. This database utilizes existing kinetic and other chemical data, and we updated those data to reflect corrections for elevated temperature and pressure conditions of EGS reservoirs.

  5. Applications of supercritical fluids.

    PubMed

    Brunner, Gerd

    2010-01-01

    This review discusses supercritical fluids in industrial and near-to-industry applications. Supercritical fluids are flexible tools for processing materials. Supercritical fluids have been applied to mass-transfer processes, phase-transition processes, reactive systems, materials-related processes, and nanostructured materials. Some applications are already at industrial capacity, whereas others remain under development. In addition to extraction, application areas include impregnation and cleaning, multistage countercurrent separation, particle formation, coating, and reactive systems such as hydrogenation, biomass gasification, and supercritical water oxidation. Polymers are modified with supercritical fluids, and colloids and emulsions as well as nanostructured materials exhibit interesting phenomena when in contact with supercritical fluids that can be industrially exploited. For these applications to succeed, the properties of supercritical fluids in combination with the materials processed must be clearly determined and fundamental knowledge of the complex behavior must be made readily available. PMID:22432584

  6. Dehydrating and Sterilizing Wastes Using Supercritical CO2

    NASA Technical Reports Server (NTRS)

    Brown, Ian J.

    2006-01-01

    A relatively low-temperature process for dehydrating and sterilizing biohazardous wastes in an enclosed life-support system exploits (1) the superior mass-transport properties of supercritical fluids in general and (2) the demonstrated sterilizing property of supercritical CO2 in particular. The wastes to be treated are placed in a chamber. Liquid CO2, drawn from storage at a pressure of 850 psi (approx.=5.9 MPa) and temperature of 0 C, is compressed to pressure of 2 kpsi (approx.=14 MPa) and made to flow into the chamber. The compression raises the temperature to 10 C. The chamber and its contents are then further heated to 40 C, putting the CO2 into a supercritical state, in which it kills microorganisms in the chamber. Carrying dissolved water, the CO2 leaves the chamber through a back-pressure regulator, through which it is expanded back to the storage pressure. The expanded CO2 is refrigerated to extract the dissolved water as ice, and is then returned to the storage tank at 0 C

  7. 10 MW Supercritical CO2 Turbine Test

    SciTech Connect

    Turchi, Craig

    2014-01-29

    The Supercritical CO2 Turbine Test project was to demonstrate the inherent efficiencies of a supercritical carbon dioxide (s-CO2) power turbine and associated turbomachinery under conditions and at a scale relevant to commercial concentrating solar power (CSP) projects, thereby accelerating the commercial deployment of this new power generation technology. The project involved eight partnering organizations: NREL, Sandia National Laboratories, Echogen Power Systems, Abengoa Solar, University of Wisconsin at Madison, Electric Power Research Institute, Barber-Nichols, and the CSP Program of the U.S. Department of Energy. The multi-year project planned to design, fabricate, and validate an s-CO2 power turbine of nominally 10 MWe that is capable of operation at up to 700°C and operates in a dry-cooled test loop. The project plan consisted of three phases: (1) system design and modeling, (2) fabrication, and (3) testing. The major accomplishments of Phase 1 included: Design of a multistage, axial-flow, s-CO2 power turbine; Design modifications to an existing turbocompressor to provide s-CO2 flow for the test system; Updated equipment and installation costs for the turbomachinery and associated support infrastructure; Development of simulation tools for the test loop itself and for more efficient cycle designs that are of greater commercial interest; Simulation of s-CO2 power cycle integration into molten-nitrate-salt CSP systems indicating a cost benefit of up to 8% in levelized cost of energy; Identification of recuperator cost as a key economic parameter; Corrosion data for multiple alloys at temperatures up to 650ºC in high-pressure CO2 and recommendations for materials-of-construction; and Revised test plan and preliminary operating conditions based on the ongoing tests of related equipment. Phase 1 established that the cost of the facility needed to test the power turbine at its full power and temperature would exceed the planned funding for Phases 2 and 3. Late

  8. Supercritical fluid extraction

    DOEpatents

    Wai, Chien M.; Laintz, Kenneth

    1994-01-01

    A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated or lipophilic crown ether or fluorinated dithiocarbamate. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.

  9. Separation of biomolecules using supercritical fluid extraction.

    PubMed

    Lucien, F P; Liong, K K; Cotton, N J; Macnaughton, S J; Foster, N R

    1993-01-01

    Supercritical fluids are increasingly being used as a replacement for more conventional organic solvents in the extraction of biomolecules from a range of matrices. Supercritical fluid extraction of essential fatty acids from fish oils is discussed. Supercritical CO2 was used to fractionate two fatty acids, EPA and DHA from fish oil ethyl esters. EPA and DHA were obtained with a purity of 58% and 67% respectively from Sardine oil with an original composition of 17% and 12%. PMID:7763846

  10. Biofilm enhanced subsurface sequestration of supercritical CO2

    NASA Astrophysics Data System (ADS)

    Mitchell, A. C.; Phillips, A.; Hiebert, R.; Gerlach, R.; Kaszuba, J.; Cunningham, A.

    2007-12-01

    In order to develop subsurface CO2 storage as a viable engineered mechanism to reduce concentrations of atmospheric CO2, any potential ¡°leakage¡± of injected supercritical CO2 (scCO2) from the ground to the atmosphere must be reduced. Here, we investigate the utility of biofilms, which are microorganism assemblages firmly attached to a surface, as a means of reducing scCO2 leakage. Firstly, experiments were performed to test whether biofilms were more resilient than planctonic cells to scCO2. Bacillus mojavensis biofilms were grown on a sand support matrix in scCO2 extractor cartridges at 30°C. B. mojavensis was also grown under suspended planctonic conditions in the same media overnight and aliquots were decanted into scCO2 extractor cartridges. Biofilm and suspended B. mojavensis samples were processed on a Supercritical Fluid Extractor with pressurization to 2000 psi at 35°C, and a 20 minute flow of scCO2. Suspended growth samples revealed a 3 log reduction in cell viability while biofilm only showed a 1 log reduction, demonstrating that B. mojavensis biofilms are more resilient than planctonic cells to scCO2. Protective extra cellular polymeric substances which make up the biofilm matrix likely provide a protective barrier against scCO2. Secondly, the ability of biofilms to grow under high pressure and reduce the permeability of porous geological matrices was investigated using a unique high pressure (8.9MPa), moderate temperature (¡Ý 32°C) flow reactor containing 40 millidarcy Berea sandstone cores. The flow reactor was inoculated with the biofilm forming organism Shewanella fridgidimarina. Electron microscopy of the rock core revealed substantial biofilm accumulation in rock pores which resulted in <99% reduction in core permeability. Permeability did not increase in response to starvation and scCO2 challenges. Viable population assays of organisms in the effluent indicated survival of the microorganisms following scCO2 challenges of <71h and

  11. Towards Overhauser DNP in supercritical CO2

    NASA Astrophysics Data System (ADS)

    van Meerten, S. G. J.; Tayler, M. C. D.; Kentgens, A. P. M.; van Bentum, P. J. M.

    2016-06-01

    Overhauser Dynamic Nuclear Polarization (ODNP) is a well known technique to improve NMR sensitivity in the liquid state, where the large polarization of an electron spin is transferred to a nucleus of interest by cross-relaxation. The efficiency of the Overhauser mechanism for dipolar interactions depends critically on fast local translational dynamics at the timescale of the inverse electron Larmor frequency. The maximum polarization enhancement that can be achieved for 1H at high magnetic fields benefits from a low viscosity solvent. In this paper we investigate the option to use supercritical CO2 as a solvent for Overhauser DNP. We have investigated the diffusion constants and longitudinal nuclear relaxation rates of toluene in high pressure CO2. The change in 1H T1 by addition of TEMPO radical was analyzed to determine the Overhauser cross-relaxation in such a mixture, and is compared with calculations based on the Force Free Hard Sphere (FFHS) model. By analyzing the relaxation data within this model we find translational correlation times in the range of 2-4 ps, depending on temperature, pressure and toluene concentration. Such short correlation times may be instrumental for future Overhauser DNP applications at high magnetic fields, as are commonly used in NMR. Preliminary DNP experiments have been performed at 3.4 T on high pressure superheated water and model systems such as toluene in high pressure CO2.

  12. Towards Overhauser DNP in supercritical CO2.

    PubMed

    van Meerten, S G J; Tayler, M C D; Kentgens, A P M; van Bentum, P J M

    2016-06-01

    Overhauser Dynamic Nuclear Polarization (ODNP) is a well known technique to improve NMR sensitivity in the liquid state, where the large polarization of an electron spin is transferred to a nucleus of interest by cross-relaxation. The efficiency of the Overhauser mechanism for dipolar interactions depends critically on fast local translational dynamics at the timescale of the inverse electron Larmor frequency. The maximum polarization enhancement that can be achieved for (1)H at high magnetic fields benefits from a low viscosity solvent. In this paper we investigate the option to use supercritical CO2 as a solvent for Overhauser DNP. We have investigated the diffusion constants and longitudinal nuclear relaxation rates of toluene in high pressure CO2. The change in (1)H T1 by addition of TEMPO radical was analyzed to determine the Overhauser cross-relaxation in such a mixture, and is compared with calculations based on the Force Free Hard Sphere (FFHS) model. By analyzing the relaxation data within this model we find translational correlation times in the range of 2-4ps, depending on temperature, pressure and toluene concentration. Such short correlation times may be instrumental for future Overhauser DNP applications at high magnetic fields, as are commonly used in NMR. Preliminary DNP experiments have been performed at 3.4T on high pressure superheated water and model systems such as toluene in high pressure CO2. PMID:27082277

  13. Supercritical fluid regeneration of adsorbents

    NASA Astrophysics Data System (ADS)

    Defilippi, R. P.; Robey, R. J.

    1983-05-01

    The results of a program to perform studies supercritical (fluid) carbon dioxide (SCF CO2) regeneration of adsorbents, using samples of industrial wastewaters from manufacturing pesticides and synthetic solution, and to estimate the economics of the specific wastewater treatment regenerations, based on test data are given. Processing costs for regenerating granular activated carbon GAC) for treating industrial wastewaters depend on stream properties and regeneration throughput.

  14. EGS rock reactions with Supercritical CO2 saturated with water and water saturated with Supercritical CO2

    SciTech Connect

    Earl D. Mattson; Travis L. McLing; William Smith; Carl Palmer

    2013-02-01

    EGS using CO2 as a working fluid will likely involve hydro-shearing low-permeability hot rock reservoirs with a water solution. After that process, the fractures will be flushed with CO2 that is maintained under supercritical conditions (> 70 bars). Much of the injected water in the main fracture will be flushed out with the initial CO2 injection; however side fractures, micro fractures, and the lower portion of the fracture will contain connate water that will interact with the rock and the injected CO2. Dissolution/precipitation reactions in the resulting scCO2/brine/rock systems have the potential to significantly alter reservoir permeability, so it is important to understand where these precipitates form and how are they related to the evolving ‘free’ connate water in the system. To examine dissolution / precipitation behavior in such systems over time, we have conducted non-stirred batch experiments in the laboratory with pure minerals, sandstone, and basalt coupons with brine solution spiked with MnCl2 and scCO2. The coupons are exposed to liquid water saturated with scCO2 and extend above the water surface allowing the upper portion of the coupons to be exposed to scCO2 saturated with water. The coupons were subsequently analyzed using SEM to determine the location of reactions in both in and out of the liquid water. Results of these will be summarized with regard to significance for EGS with CO2 as a working fluid.

  15. Operation and analysis of a supercritical CO2 Brayton cycle.

    SciTech Connect

    Wright, Steven Alan; Radel, Ross F.; Vernon, Milton E.; Pickard, Paul S.; Rochau, Gary Eugene

    2010-09-01

    Sandia National Laboratories is investigating advanced Brayton cycles using supercritical working fluids for use with solar, nuclear or fossil heat sources. The focus of this work has been on the supercritical CO{sub 2} cycle (S-CO2) which has the potential for high efficiency in the temperature range of interest for these heat sources, and is also very compact, with the potential for lower capital costs. The first step in the development of these advanced cycles was the construction of a small scale Brayton cycle loop, funded by the Laboratory Directed Research & Development program, to study the key issue of compression near the critical point of CO{sub 2}. This document outlines the design of the small scale loop, describes the major components, presents models of system performance, including losses, leakage, windage, compressor performance, and flow map predictions, and finally describes the experimental results that have been generated.

  16. Electrochemistry in supercritical fluids.

    PubMed

    Branch, Jack A; Bartlett, Philip N

    2015-12-28

    A wide range of supercritical fluids (SCFs) have been studied as solvents for electrochemistry with carbon dioxide and hydrofluorocarbons (HFCs) being the most extensively studied. Recent advances have shown that it is possible to get well-resolved voltammetry in SCFs by suitable choice of the conditions and the electrolyte. In this review, we discuss the voltammetry obtained in these systems, studies of the double-layer capacitance, work on the electrodeposition of metals into high aspect ratio nanopores and the use of metallocenes as redox probes and standards in both supercritical carbon dioxide-acetonitrile and supercritical HFCs. PMID:26574527

  17. Electrochemistry in supercritical fluids

    PubMed Central

    Branch, Jack A.; Bartlett, Philip N.

    2015-01-01

    A wide range of supercritical fluids (SCFs) have been studied as solvents for electrochemistry with carbon dioxide and hydrofluorocarbons (HFCs) being the most extensively studied. Recent advances have shown that it is possible to get well-resolved voltammetry in SCFs by suitable choice of the conditions and the electrolyte. In this review, we discuss the voltammetry obtained in these systems, studies of the double-layer capacitance, work on the electrodeposition of metals into high aspect ratio nanopores and the use of metallocenes as redox probes and standards in both supercritical carbon dioxide–acetonitrile and supercritical HFCs. PMID:26574527

  18. Forsterite Carbonation in Wet Supercritical CO2 and Sodium Citrate

    NASA Astrophysics Data System (ADS)

    Qiu, L.; Schaef, T.; Wang, Z.; Miller, Q.; McGrail, P.

    2013-12-01

    Lin Qiu1*, Herbert T. Schaef2, Zhengrong Wang1, Quin R.S. Miller3, BP McGrail2 1. Yale University, New Haven, CT, USA 2. Pacific Northwest National Laboratory, Richland, WA, USA 3. University of Wyoming, Laramie, WY, USA Geologic reservoirs for managing carbon emissions (mostly CO2) have expanded over the last 5 years to include unconventional formations including basalts and fractured shales. Recently, ~1000 metric tons of CO2 was injected into the Columbia River Basalt (CRB) in Eastern Washington as part of the Wallula Pilot Project, Big Sky Regional Carbon Partnership. Based on reservoir conditions, the injected CO2 is present as a supercritical fluid that dissolves into the formation water over time, and reacts with basalt components to form carbonate minerals. In this paper, we discuss mineral transformation reactions occurring when the forsterite (Mg2SiO4) is exposed to wet scCO2 in equilibrium with pure water and sodium citrate solutions. Forsterite was selected as it is an important olivine group mineral present in igneous and mafic rocks. Citrate was selected as it has been shown to enhance mineral dissolution and organic ligands are possible degradation products of the microbial communities present in the formational waters of the CRB. For the supercritical phase, transformation reactions were examined by in situ high pressure x-ray diffraction (HXRD) in the presence of supercritical carbon dioxide (scCO2) in contact with water and sodium citrate solutions at conditions relevant to carbon sequestration. Experimental results show close-to-complete dissolution of forsterite in contact with scCO2 equilibrated with pure water for 90 hours (90 bar and 50°C). Under these conditions, thin films of water coated the mineral surface, providing a mechanism for silicate dissolution and transport of cations necessary for carbonate formation. The primary crystalline component initially detected with in situ HXRD was the hydrated magnesium carbonate, nesquehonite [Mg

  19. Homopolymers and Micelles in Supercritical CO2 : a SANS Study

    NASA Astrophysics Data System (ADS)

    Chillura-Martino, D.; McClain, J. B.; Canelas, D.; Betts, D.; Samulski, E. T.; Desimone, J. M.; Wignall, G. D.; Londono, J. D.; Triolo, R.

    1996-03-01

    Supercritical Carbon Dioxide (SC-CO_2) is becoming an attractive alternative to the liquid solvents traditionally used as polymerization media. We have applied small-angle neutron scattering (SANS) to characterize homopolymers and micellar systems in SC-CO_2. Although polymerizations are carried out at high pressures, the penetrating power of the neutron beam means that typical cell windows are virtually transparent. Homopolymers studied include polyfluoro-octyl acrylate (PFOA), hexafluoro-polypropylene oxide and Polydimethyl-siloxane. Also, copolymers of amphiphilic character in CO_2, were characterized via SANS. Systems studied were PFOA-polystyrene diblocks and PFOA-polyethyleneoxide (PFOA-PEO) graft copolymers, which swell as the CO2 medium is saturated with water. This work illustrates the utility of SANS to measure molecular dimensions, thermodynamic variables, molecular weights, micelle structures etc. in supercritical CO_2.

  20. Supercritical fluids cleaning

    SciTech Connect

    Butner, S.; Hjeresen, D.; Silva, L.; Spall, D.; Stephenson, R.

    1991-01-01

    This paper discusses a proposed multi-party research and development program which seeks to develop supercritical fluid cleaning technology as an alternative to existing solvent cleaning applications. While SCF extraction technology has been in commercial use for several years, the use of these fluids as cleaning agents poses several new technical challenges. Problems inherent in the commercialization of SCF technology include: the cleaning efficacy and compatibility of supercritical working fluids with the parts to be cleaned must be assessed for a variety of materials and components; process parameters and equipment design Have been optimized for extractive applications and must be reconsidered for application to cleaning; and co-solvents and entrainers must be identified to facilitate the removal of polar inorganic and organic contaminants, which are often not well solvated in supercritical systems. The proposed research and development program would address these issues and lead to the development and commercialization of viable SCF-based technology for precision cleaning applications. This paper provides the technical background, program scope, and delineates the responsibilities of each principal participant in the program.

  1. QENS from polymeric micelles in supercritical CO2

    NASA Astrophysics Data System (ADS)

    Triolo, R.; Arrighi, V.; Triolo, A.; Migliardo, P.; Magazù, S.; McClain, J. B.; Betts, D.; DeSimone, J. M.; Middendorf, H. D.

    2000-04-01

    We report QENS measurements from PS-b-PFOA aggregates in supercritical CO2. These consist of dense cores of CO2-insoluble polystyrene surrounded by a `corona' of PFOA surfactant molecules whose CO2-philic groups interface with supercritical CO2. Lineshapes are dominated by localized diffusive modes and segmental dynamics of the anchored, finite-length PFOA chains. For Q˜0.6 Å-1, we obtain effective diffusion coefficients of ≈0.8×10-6 cm2/sec. At higher Q, a single component is not sufficient as shown by excess intensity on the flanks. For Q>1.5 Å-1, the wings reflect contributions due to a distribution of faster, more localized chain modes.

  2. Investigations of supercritical CO2 Rankine cycles for geothermal power plants

    SciTech Connect

    Sabau, Adrian S; Yin, Hebi; Qualls, A L; McFarlane, Joanna

    2011-01-01

    Supercritical CO2 Rankine cycles are investigated for geothermal power plants. The system of equations that describe the thermodynamic cycle is solved using a Newton-Rhapson method. This approach allows a high computational efficiency of the model when thermophysical properties of the working fluid depend strongly on the temperature and pressure. Numerical simulation results are presented for different cycle configurations in order to assess the influences of heat source temperature, waste heat rejection temperatures and internal heat exchanger design on cycle efficiency. The results show that thermodynamic cycle efficiencies above 10% can be attained with the supercritical brayton cycle while lower efficiencies can be attained with the transcritical CO2 Rankine cycle.

  3. Metal extraction from the artificially contaminated soil using supercritical CO2 with mixed ligands.

    PubMed

    Park, Kwangheon; Lee, Jeongken; Sung, Jinhyun

    2013-04-01

    Supercritical fluids have good penetrating power with a high capacity to dissolve certain solutes in the fluid itself, making it applicable for soil cleaning. Supercritical CO2 along with mixed ligands has been used for cleaning artificially contaminated soil. The extraction of metal from the soil was successful, and the molar ratio of ligands to the extracted metal was as low as 3. Complicated structures with a large surface area of the real soil seemed to cause the lower efficiency. Reduced efficiency was also observed over time after the sample preparation, indicating the possibility of chemisorption of the metal ion onto the soil. The use of supercritical CO2 with dissolved mixed ligands was sufficient to extract metal from the soil. PMID:23347618

  4. Corrosion in supercritical fluids

    SciTech Connect

    Propp, W.A.; Carleson, T.E.; Wai, Chen M.; Taylor, P.R.; Daehling, K.W.; Huang, Shaoping; Abdel-Latif, M.

    1996-05-01

    Integrated studies were carried out in the areas of corrosion, thermodynamic modeling, and electrochemistry under pressure and temperature conditions appropriate for potential applications of supercritical fluid (SCF) extractive metallurgy. Carbon dioxide and water were the primary fluids studied. Modifiers were used in some tests; these consisted of 1 wt% water and 10 wt% methanol for carbon dioxide and of sulfuric acid, sodium sulfate, ammonium sulfate, and ammonium nitrate at concentrations ranging from 0.00517 to 0.010 M for the aqueous fluids. The materials studied were Types 304 and 316 (UNS S30400 and S31600) stainless steel, iron, and AISI-SAE 1080 (UNS G10800) carbon steel. The thermodynamic modeling consisted of development of a personal computer-based program for generating Pourbaix diagrams at supercritical conditions in aqueous systems. As part of the model, a general method for extrapolating entropies and related thermodynamic properties from ambient to SCF conditions was developed. The experimental work was used as a tool to evaluate the predictions of the model for these systems. The model predicted a general loss of passivation in iron-based alloys at SCF conditions that was consistent with experimentally measured corrosion rates and open circuit potentials. For carbon-dioxide-based SCFs, measured corrosion rates were low, indicating that carbon steel would be suitable for use with unmodified carbon dioxide, while Type 304 stainless steel would be suitable for use with water or methanol as modifiers.

  5. SOLUBILITY OF ORGANIC BIOCIDES IN SUPERCRITICAL CO2 AND CO2+ COSOLVENT MIXTURES

    EPA Science Inventory

    Solubilities of four organic biocides in supercritical carbon dioxide (Sc-CO2) were measured using a dynamic flowr apparatus over a pressure range of 10 to 30 MPa and temperature of 35-80 degrees C. The biocides studied were: Amical-48 (diiodomethyl p-tolyl sulfone), chlorothalo...

  6. Supercritical Fluid Infusion of Iron Additives in Polymeric Matrices

    NASA Technical Reports Server (NTRS)

    Nazem, Negin; Taylor, Larry T.

    1999-01-01

    The objective of this project was the experimentation to measure preparation of iron nanophases within polymeric matrices via supercritical fluid infusion of iron precursors followed by thermal reduction. Another objective was to determine if supercritical CO2 could infuse into the polymer. The experiment is described along with the materials, and the supercritical fluid infusion and cure procedures. X-ray photoelectron spectra and transmission electron micrographs were obtained. The results are summarized in charts, and tables.

  7. Physical and Chemical Effects of Two-Phase Brine/Supercritical-CO2 Fluid Flow on Clastic Rocks: Real-Time Monitoring and NMR Imaging of Flow-Through Core Experiments

    NASA Astrophysics Data System (ADS)

    Shaw, C. A.; Vogt, S.; Maneval, J. E.; Brox, T.; Skidmore, M. L.; Codd, S. L.; Seymour, J. D.

    2010-12-01

    Sandstone core samples were challenged with a supercritical CO2-saturated brine mixture in a laboratory flow-through core reactor system over a range of temperatures and brine strengths. Cores of quartz arenite from the Berea formation were selected to represent ideal ‘clean’ sandstone These laboratory experiments potentially provide an analog for the acidification of pore fluids near the brine/CO2 interface during CO2 flooding of depleted clastic hydrocarbon reservoirs for carbon sequestration. Flow in the reactor was perpendicular to bedding. Initial experiments were run at 50°C and 100°C with brine concentrations of 1g/L and 10g/L (TDS) to test effects of different temperatures and brine compositions. Real-time monitoring of fluid pH and conductivity provided a measure of reaction rates. Introduction of supercritical CO2 into the brine-saturated cores initiated a reduction in pH accompanied by an increase in conductivity. NMR images of fresh cores were compared with images of challenged cores using a protocol for pixel-by-pixel comparison to determine the effects on bulk pore volume and geometry. Two types of imaging experiments were conducted: multi-slice spin echo and 3-D spin echo images. Multi-slice experiments had a slice thickness of 1.5 mm and an in-plane resolution of 0.27 mm x 0.27 mm, and 3-D experiments had a resolution of 0.47 mm x 0.55 mm x 0.55mm. Imaging results reflected the observed changes in the physical and chemical structure post-challenge. Two-dimensional relaxation correlation experiments were also conducted to probe the pore sizes, connectivity and fluid saturation of the rock cores before and after challenging. Chemical analyses and microscopic examination of the challenged cores will provide a better understanding of alteration in the cores and the changes in the volume, geometry and connectivity of pore space.

  8. RPCSIM-SCO2 (Reactor Power and Control SIMulator for Supercritical CO2)

    SciTech Connect

    Wright, Steven A.

    2012-09-12

    The RPCSIM-SCO2 code performs a dynamic simulation of a supercritical CO2 (carbon dioxide) Brayton cycle loop. The code is based on the MathLabTM program SimulinkTM from Mathworks. The Supercritical CO2 (S-CO2) model uses direct calls to the National Institute of Standards Refprop 9.0 Fortran library for the Equation-of-State (EOS) model for the CO2 working fluid (Lemmon, 2010). The calls to Refprop are made in the form of Simulink s-Functions that use a C interface to directly call the compiled Refprop fortran program library functions. Minor changes to the code can be made to use other working fluids. The code is intended to be used to perform many different types of dynamic cycle analysis for supercritical CO2 power producing systems. The code will calculate the transient temperature and pressure and all other thermodynamic properties at the inlet and outlet of each component given user supplied inputs such as rotor shaft speed, and heater power.

  9. RPCSIM-SCO2 (Reactor Power and Control SIMulator for Supercritical CO2)

    Energy Science and Technology Software Center (ESTSC)

    2012-09-12

    The RPCSIM-SCO2 code performs a dynamic simulation of a supercritical CO2 (carbon dioxide) Brayton cycle loop. The code is based on the MathLabTM program SimulinkTM from Mathworks. The Supercritical CO2 (S-CO2) model uses direct calls to the National Institute of Standards Refprop 9.0 Fortran library for the Equation-of-State (EOS) model for the CO2 working fluid (Lemmon, 2010). The calls to Refprop are made in the form of Simulink s-Functions that use a C interface tomore » directly call the compiled Refprop fortran program library functions. Minor changes to the code can be made to use other working fluids. The code is intended to be used to perform many different types of dynamic cycle analysis for supercritical CO2 power producing systems. The code will calculate the transient temperature and pressure and all other thermodynamic properties at the inlet and outlet of each component given user supplied inputs such as rotor shaft speed, and heater power.« less

  10. Supercritical fluid extraction in natural products analyses.

    PubMed

    Nahar, Lutfun; Sarker, Satyajit D

    2012-01-01

    Supercritical fluids (SCFs) are increasingly replacing the organic solvents, e.g., n-hexane, chloroform, dichloromethane, or methanol, that are conventionally used in industrial extraction, purification, and recrystallization operations because of regulatory and environmental pressures on hydrocarbon and ozone-depleting emissions. In natural products extraction and isolation, supercritical fluid extraction (SFE), especially employing supercritical CO(2), has become a popular choice. Sophisticated modern technologies allow precise regulation of changes in temperature and pressure, and thus manipulation of solvating property of the SCF, which helps the extraction of natural products of a wide range of polarities. This chapter deals mainly with the application of the SFE technology in the natural products extraction and isolation, and outlines various methodologies with specific examples. PMID:22367893

  11. Supercritical fluid technology

    SciTech Connect

    Penninger, J.M.L.; McHugh, M.A.; Radosz, M.; Krukonis, V.J.

    1985-01-01

    This book presents the state-of-the-art in the science and technology of supercritical fluid (scf) processing. Current research as described in the book, focuses on developments in equations of state for binary and multicomponent mixtures (including polymer solutions), solubility measurements at near-critical conditions, measurements of critical properties of binary mixtures and their correlation with equations of state. Progress in thermodynamics, coupled with advances in the design and construction of high pressure equipment, has opened up a wide avenue of commercial application (e.g. decaffeination of coffee beans, extractions of flavours and spices, purification of pharmaceutical products, separations of polymeric materials, deodorization and deacidification of vegetable oils, fractionation of fatty acids, coal liquefaction, wood delignitication, etc.)

  12. Sorption Phase of Supercritical CO2 in Silica Aerogel: Experiments and Mesoscale Computer Simulations

    SciTech Connect

    Rother, Gernot; Vlcek, Lukas; Gruszkiewicz, Miroslaw {Mirek} S; Chialvo, Ariel A; Anovitz, Lawrence {Larry} M; Banuelos, Jose Leo; Wallacher, Dirk; Grimm, Nico; Cole, David

    2014-01-01

    Adsorption of supercritical CO2 in nanoporous silica aerogel was investigated by a combination of experiments and molecular-level computer modeling. High-pressure gravimetric and vibrating tube densimetry techniques were used to measure the mean pore fluid density and excess sorption at 35 C and 50 C and pressures of 0-200 bar. Densification of the pore fluid was observed at bulk fluid densities below 0.7 g/cm3. Far above the bulk fluid density, near-zero sorption or weak depletion effects were measured, while broad excess sorption maxima form in the vicinity of the bulk critical density region. The CO2 sorption properties are very similar for two aerogels with different bulk densities of 0.1 g/cm3 and 0.2 g/cm3, respectively. The spatial distribution of the confined supercritical fluid was analyzed in terms of sorption- and bulk-phase densities by means of the Adsorbed Phase Model (APM), which used data from gravimetric sorption and small-angle neutron scattering experiments. To gain more detailed insight into supercritical fluid sorption, large-scale lattice gas GCMC simulations were utilized and tuned to resemble the experimental excess sorption data. The computed three-dimensional pore fluid density distributions show that the observed maximum of the excess sorption near the critical density originates from large density fluctuations pinned to the pore walls. At this maximum, the size of these fluctuations is comparable to the prevailing pore sizes.

  13. Recovery of Minerals in Martian Soils Via Supercritical Fluid Extraction

    NASA Astrophysics Data System (ADS)

    Debelak, Kenneth A.; Roth, John A.

    2001-03-01

    We are investigating the use of supercritical fluids to extract mineral and/or carbonaceous material from Martian surface soils and its igneous crust. Two candidate supercritical fluids are carbon dioxide and water. The Martian atmosphere is composed mostly of carbon dioxide (approx. 95.3%) and could therefore provide an in-situ source of carbon dioxide. Water, although present in the Martian atmosphere at only approx. 0.03%, is also a candidate supercritical solvent. Previous work done with supercritical fluids has focused primarily on their solvating properties with organic compounds. Interestingly, the first work reported by Hannay and Hogarth at a meeting of the Royal Society of London in 1879 observed that increasing or decreasing the pressure caused several inorganic salts e.g., cobalt chloride, potassium iodide, and potassium bromide, to dissolve or precipitate in supercritical ethanol. In high-pressure boilers, silica, present in most boiler feed waters, is dissolved in supercritical steam and transported as dissolved silica to the turbine blades. As the pressure is reduced the silica precipitates onto the turbine blades eventually requiring the shutdown of the generator. In supercritical water oxidation processes for waste treatment, dissolved salts present a similar problem. The solubility of silicon dioxide (SiO2) in supercritical water is shown. The solubility curve has a shape characteristic of supercritical systems. At a high pressure (greater than 1750 atmospheres) increasing the temperature results in an increase in solubility of silica, while at low pressures, less than 400 atm., the solubility decreases as temperature increases. There are only a few studies in the literature where supercritical fluids are used in extractive metallurgy. Bolt modified the Mond process in which supercritical carbon monoxide was used to produce nickel carbonyl (Ni(CO)4). Tolley and Tester studied the solubility of titanium tetrachloride (TiCl4) in supercritical CO2

  14. Supercritical CO2 extraction and purification of compounds with antioxidant activity.

    PubMed

    Díaz-Reinoso, Beatriz; Moure, Andrés; Domínguez, Herminia; Parajó, Juan Carlos

    2006-04-01

    Supercritical fluid extraction (SCFE), based on the utilization of a fluid under supercritical conditions, is a technology suitable for extraction and purification of a variety of compounds, particularly those that have low volatility and/or are susceptible to thermal degradation. The interest in SCFE is promoted by legal limitations of conventional solvents for food and pharmaceutical uses. The physicochemical properties of supercritical CO2 (higher diffusivity, lower viscosity, and lower surface tension than conventional solvents) facilitate mass transfer and allow an environmentally friendly operation. This article presents a comprehensive compilation of data on the supercritical CO2 extraction of antioxidant compounds from vegetal materials, with particular attention to those of a phenolic nature. Aspects concerning the supercritical operation for extraction and fractionation of antioxidants compounds are considered, including equilibrium solubility of pure compounds and effects of the operational conditions on the antioxidant activity of isolated fractions. The data are compared to those reported for synthetic antioxidants and natural extracts obtained by conventional solvent extraction from vegetal matrices. PMID:16569029

  15. Acoustic emission monitoring of hydraulic fracturing laboratory experiment with supercritical and liquid CO2

    NASA Astrophysics Data System (ADS)

    Ishida, Tsuyoshi; Aoyagi, Kazuhei; Niwa, Tomoya; Chen, Youqing; Murata, Sumihiko; Chen, Qu; Nakayama, Yoshiki

    2012-08-01

    Carbon dioxide (CO2) is often used for enhanced oil recovery in depleted petroleum reservoirs, and its behavior in rock is also of interest in CO2 capture and storage projects. CO2 usually becomes supercritical (SC-CO2) at depths greater than 1,000 m, while it is liquid (L-CO2) at low temperatures. The viscosity of L-CO2 is one order lower than that of normal liquid water, and that of SC-CO2 is much lower still. To clarify fracture behavior induced with injection of the low viscosity fluids, we conducted hydraulic fracturing experiments using 17 cm cubic granite blocks. The AE sources with the SC- and L-CO2 injections tend to distribute in a larger area than those with water injection, and furthermore, SC-CO2 tended to generate cracks extending more three dimensionally rather than along a flat plane than L-CO2. It was also found that the breakdown pressures for SC- and L-CO2 injections are expected to be considerably lower than for water.

  16. Modification of SiO2 nanowires with metallic nanocrystals from supercritical CO2.

    PubMed

    Ye, Xiang-Rong; Zhang, Hai-Feng; Lin, Yuehe; Wang, Lai-Sheng; Wai, Chien M

    2004-01-01

    Through hydrogen reduction of metal precursors in supercritical CO2, Cu, and Pd, nanocrystals were deposited onto SiO2 nanowires to form different types of nanostructured materials, including nanocrystal-nanowire, spherical aggregation-nanowire, shell-nanowire composites, and "mesoporous" metals supported by the framework of nanowires. This supercritical fluid deposition technique is an attractive approach for modifying nanowires because of its generality and simplicity; the modified nanowires could be useful as catalysts and for further fabrication of multifunctional composites. PMID:15112546

  17. Alteration of bentonite when contacted with supercritical CO2

    NASA Astrophysics Data System (ADS)

    Jinseok, K.; Jo, H. Y.; Yun, S. T.

    2014-12-01

    Deep saline formations overlaid by impermeable caprocks with a high sealing capacity are attractive CO2 storage reservoirs. Shales, which consist of mainly clay minerals, are potential caprocks for the CO2 storage reservoirs. The properties of clay minerals in shales may affect the sealing capacity of shales. In this study, changes in clay minerals' properties when contacted with supercritical (SC) CO2 at various conditions were investigated. Bentonite, whichis composed of primarily montmorillonite, was used as the clay material in this study. Batch reactor tests on wet bentonite samples in the presence of SC CO2 with or without aqueous phases were conducted at high pressure (12 MPa) and moderate temperature (50 oC) conditions for a week. Results show that the bentonite samples obtained from the tests with SC CO2 had less change in porosity than those obtained from the tests without SC CO2 (vacuum-drying) at a given reaction time, indicating that the bentonite samples dried in the presence of SC CO2 maintained their structure. These results suggest that CO2 molecules can diffuse into interlayer of montmorillonite, which is a primary mineral of bentonite, and form a single CO2 molecule layer or double CO2 molecule layers. The CO2 molecules can displace water molecules in the interlayer, resulting in maintaining the interlayer spacing when dehydration occurs. Noticeable changes in reacted bentonite samples obtained from the tests with an aqueous phase (NaCl, CaCl2, or sea water) are decreases in the fraction of plagioclase and pyrite and formation of carbonate minerals (i.e., calcite and dolomite) and halite. In addition, no significant exchanges of Na or Ca on the exchangeable complex of the montmorillonite in the presence of SC CO2 occurred, resulting in no significant changes in the swelling capacity of bentonite samples after reacting with SC CO2 in the presence of aqueous phases. These results might be attributed by the CO2 molecule layer, which prevents

  18. Solvation of Esters and Ketones in Supercritical CO2.

    PubMed

    Kajiya, Daisuke; Imanishi, Masayoshi; Saitow, Ken-ichi

    2016-02-01

    Vibrational Raman spectra for the C═O stretching modes of three esters with different functional groups (methyl, a single phenyl, and two phenyl groups) were measured in supercritical carbon dioxide (scCO2). The results were compared with Raman spectra for three ketones involving the same functional groups, measured at the same thermodynamic states in scCO2. The peak frequencies of the Raman spectra of these six solute molecules were analyzed by decomposition into the attractive and repulsive energy components, based on the perturbed hard-sphere theory. For all solute molecules, the attractive energy is greater than the repulsive energy. In particular, a significant difference in the attractive energies of the ester-CO2 and ketone-CO2 systems was observed when the methyl group is attached to the ester or ketone. This difference was significantly reduced in the solute systems with a single phenyl group and was completely absent in those with two phenyl groups. The optimized structures among the solutes and CO2 molecules based on quantum chemical calculations indicate that greater attractive energy is obtained for a system where the oxygen atom of the ester is solvated by CO2 molecules. PMID:26741296

  19. Compositional changes of reservoir rocks through the injection of supercritical CO2

    NASA Astrophysics Data System (ADS)

    Scherf, Ann-Kathrin; Schulz, Hans-Martin; Zetzl, Carsten; Smirnova, Irina; Andersen, Jenica; Vieth, Andrea

    2010-05-01

    The European project CO2SINK is the first project on the on-shore underground storage of carbon dioxide in Europe. CO2SINK is part of the ongoing efforts to understand the impact, problems, and likelihood of using deep saline aquifers for long term storage of CO2. In Ketzin (north-east Germany, 40 km west of Berlin) a saline sandstone aquifer of the younger Triassic (Stuttgart Formation) has been chosen as a reservoir for the long-term storage of carbon dioxide. Our monitoring focuses on the composition and mobility of the organic carbon pools within the saline aquifer and their changes due to the storage of carbon dioxide. Supercritical carbon dioxide is known as an excellent solvent of non- to moderately polar organic compounds, depending on temperature and pressure (Hawthorne, 1990). The extraction of organic matter (OM) from reservoir rock, using multiple extraction methods, allows insight into the composition of the OM and the biomarker inventory of the deep biosphere. The extraction of reservoir rock using supercritical CO2 may additionally simulate the impact of CO2 storage on the deep biosphere by the possible mobilisation of OM. We will present compound specific results from laboratory CO2 extraction experiments on reservoir rocks from the CO2 storage site in Ketzin, Germany. A total of five rock samples (silt and sandstones) from the injection well and two observation wells were applied to supercritical CO2 extraction. In the experimental setup, a supercritical fluid extractor is used to simulate the conditions within the saline aquifer. The results show distinct quantitative and qualitative differences in extraction yields between the rock samples. This may be due to differences in mineralogy and porosity (12 - 27%; Norden et al., 2007a, b, c), which seem to be extraction-controlling key factors. Furthermore, the results illustrate that the amount of extracted materials depends on the length of the time interval in which CO2 flows through the rock

  20. Supercritical Fluid Reactions for Coal Processing

    SciTech Connect

    Eckert, Charles A

    1997-07-01

    Exciting opportunities exist for the application of supercritical fluid (SCF) reactions for the pre-treatment of coal. Utilizing reactants which resemble the organic nitrogen containing components of coal, we propose to develop a method to tailor chemical reactions in supercritical fluid solvents for the specific application of coal denitrogenation. The Diels-Alder reaction of anthracene and 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) was chosen as the model system and was investigated in supercritical carbon dioxide. Kinetic data have been previously collected for pure CO2 at 40C and pressures between the critical pressure of CO2 (73.8 bar) and 216 bar. These data support the theory of local density enhancements suggested in the literature. Data taken at 50C and pressures ranging from 70 bar to 195 bar are currently reported; they do not exhibit the molecular clustering evident closer to the critical temperature. The data taken at 40C are now being used to construct mathematical forms which can model these pressure-induced kinetic changes. One promising avenue of investigation involves treating the supercritical medium as a dense gas, which allows a kinetic model based on high reference pressure fugacity coefficients to be derived.

  1. QENS from polymer aggregates in supercritical CO 2

    NASA Astrophysics Data System (ADS)

    Triolo, R.; Arrighi, V.; Triolo, A.; Migliardo, P.; Magazù, S.; McClain, J. B.; Betts, D.; DeSimone, J. M.; Middendorf, H. D.

    2000-03-01

    We report QENS measurements from PS-b-PFOA aggregates in supercritical CO 2. Line shapes are dominated by localized diffusive modes and segmental dynamics of the anchored, finite-length PFOA chains. For Q⩽0.6 Å -1, we obtain effective diffusion coefficients of ≅0.8 10 -6 cm 2/s. At higher Q, a single component is not sufficient as shown by excess intensity on the flanks. For Q⩾1.5 Å -1, the wings reflect contributions due to a distribution of faster, more localized chain modes.

  2. CFD analysis of supercritical CO2 used as HTF in a solar tower receiver

    NASA Astrophysics Data System (ADS)

    Roldán, M. I.; Fernández-Reche, J.

    2016-05-01

    The relative cost of a solar receiver can be minimized by the selection of an appropriate heat transfer fluid capable of achieving high receiver efficiencies. In a conventional central receiver system, the concentrated solar energy is transferred from the receiver tube walls to the heat transfer fluid (HTF), which passes through a heat exchanger to generate steam for a Rankine cycle. Thus, higher working fluid temperature is associated with greater efficiency in receiver and power cycle. Emerging receiver designs that can enable higher efficiencies using advanced power cycles, such as supercritical CO2 (s-CO2) closed-loop Brayton cycles, include direct heating of s-CO2 in tubular receiver designs capable of withstanding high internal fluid pressures (around 20 MPa) and temperatures (900 K). Due to the high pressures required and the presence of moving components installed in pipelines (ball-joints and/or flexible connections), the use of s-CO2 presents many technical challenges due to the compatibility of seal materials and fluid leakages of the moving connections. These problems are solved in solar tower systems because the receiver is fixed. In this regard, a preliminary analysis of a tubular receiver with s-CO2 as HTF has been developed using the design of a molten-salt receiver which was previously tested at Plataforma Solar de Almería (PSA). Therefore, a simplified CFD model has been carried out in this study in order to analyze the feasibility of s-CO2 as HTF in solar towers. Simulation results showed that the heat gained by s-CO2 was around 75% greater than the one captured by molten salts (fluid inlet temperature of 715 K), but at a pressure range of 7.5-9.7 MPa. Thus, the use of s-CO2 as HTF in solar tower receivers appears to be a promising alternative, taking into account both the operating conditions required and their maintenance cost.

  3. Surface Studies of HSLA Steel after Electrochemical Corrosion in Supercritical CO2-H2O Environment

    SciTech Connect

    Ziomek-Moroz, M. Holcomb, G. Tylczak, J Beck, J Fedkin, M. Lvov, S.

    2011-10-01

    In aqueous phase saturated with CO2, X-65 sample underwent general corrosion with formation of FeCO3. In supercritical CO2 containing water phase, two major regions are present on the sample surface after the EIS experiment. One region covered with corrosion products identified as FeCO3 and the other containing Fe, oxygen, and carbon-rich islands embedded in metal matrix identified as {alpha}-Fe. Precipitation of FeCO3 from Fe2+ and CO3 2- is responsible for formation of passive layer in oxygen-deficient, CO2 rich aqueous environment. Mechanisms of corrosion degradation occurring in supercritical CO2 as a function. Transport of supercritical CO{sub 2} is a critical element for carbon capture from fossil fuel power plants and underground sequestration. Although acceptable levels of water in supercritical CO{sub 2} (up to {approx} 5 x 10{sup -4}g/dm{sup 3}) have been established, their effects on the corrosion resistance of pipeline steels are not fully known. Moreover, the presence of SO{sub 2}, O{sub 2} impurities in addition to the water can make the fluid more corrosive and, therefore, more detrimental to service materials. Also, in this case, limited data are available on materials performance of carbon steels. to advance this knowledge, other service alloys are being investigated in the high pressure high temperature cell containing impure CO{sub 2} fluids using reliable non-destructive in-situ electrochemical methods. The electrochemical results are being augmented by a number of surface analyses of the corroded surfaces.

  4. High Resolution X-ray CMT Imaging of Supercritical CO2 in Porous Media: Experimental Challenges, Solutions, and Results

    NASA Astrophysics Data System (ADS)

    Herring, A. L.; Andersson, L.; Newell, D. L.; Carey, J. W.; Wildenschild, D.

    2013-12-01

    Geologic carbon dioxide (CO2) sequestration has been proposed as a climate change mitigation strategy to limit emissions of CO2 to the atmosphere from large fossil-fuel burning CO2 point sources; however, there are concerns associated with the long-term stability of a mobile subsurface CO2 plume. Capillary trapping of supercritical CO2 (scCO2), wherein the CO2 is held within the pore structure of the geologic matrix by capillary forces, is a more secure form of subsurface storage than structural trapping, which relies on an impermeable caprock to contain the buoyant CO2 plume. To understand the multiphase physics of CO2 transport, and to subsequently produce quantitative estimates of potential CO2 capillary trapping, it is necessary to study field, core, and pore-scale processes. X-ray computed microtomography (x-ray CMT) allows for three-dimensional (3D) in-situ visualization of fluid phases within and the physical structure of a porous medium at the pore-scale. We have designed and built a mobile experimental set-up capable of running at pressures up to 2000 PSI and temperatures up to 50°C, made with materials that are compatible with corrosive fluids. Our experimental procedure includes pressurizing, mixing, and separating fluids; and subsequently running immiscible drainage and imbibition flow experiments with brine and supercritical CO2. With this set-up and procedure, we successfully conducted a brine-scCO2 drainage experiment in Bentheimer sandstone at 1200 PSI and 36°C, and confirmed and quantified CO2 flow in the sandstone core via synchrotron-based x-ray CMT with a resolution of 4.65 μm at the Advanced Photon Source at Argonne National Laboratory. We have proven that we can observe, on a pore-scale basis, the movement of supercritical CO2 within a porous media. The properties of supercritical CO2 (e.g. viscosity, density, interfacial tension and solubility in brine) vary significantly with changes in pressure and temperature; consequently, precise

  5. Formation of Magnesite at Low Temperature in Mineral:Supercritical CO2 Systems

    NASA Astrophysics Data System (ADS)

    Qafoku, O.; Hu, J.; Arey, B.; Liu, J.; Ilton, E. S.; Felmy, A.

    2013-12-01

    One of the most promising options for mitigating the impacts of greenhouse gases on global warming is storage and sequestration of the anthropogenic CO2 in deep geologic formations. Consequently, evaluating mineral-fluid interaction in aqueous systems saturated with supercritical CO2 (scCO2) has been the focus for subsurface CO2 storage research. An important factor in assessing mineral-fluid interactions is the potential for the formation of stable divalent metal carbonates, principally Ca and Mg, which can immobilize the disposed CO2 as mineral precipitates. The formation of some of these phases, especially the Mg anhydrous phase magnesite (MgCO3), has been hindered by slow precipitation kinetics owing to the strong affinity of Mg2+ ion for the waters of hydration. Understanding conditions that lead to formation of magnesite at temperatures significant to subsurface disposal of CO2 can be substantial in the development of efficient carbon sequestration techniques. Here we present recently obtained experimental data on the formation of magnesite at low temperature (as low as 350C) and microscopy data that can elucidate factors that might contribute to magnesite formation. The experimental studies were conducted over a range of temperature, pressure, pH, and initial Mg(HCO3)2 concentration to map out the specific solution phase conditions which result in nucleation of magnesite in aqueous solution saturated with scCO2.

  6. The Role of H2O in the Carbonation of Forsterite in Supercritical CO2

    SciTech Connect

    Kwak, Ja Hun; Hu, Jian Z.; Turcu, Romulus VF; Rosso, Kevin M.; Ilton, Eugene S.; Wang, Chong M.; Sears, Jesse A.; Engelhard, Mark H.; Felmy, Andrew R.; Hoyt, David W.

    2011-07-01

    The water concentration dependence of forsterite carbonation in supercritical CO2 (scCO2) at 80°C and 76 bars was investigated by a combination of NMR, XRD, TEM and XPS. Reaction products were not detected using scCO2 alone without added H2O. When trace amounts of water were included, limited reaction was observed. Below saturation, reaction products were a mixture of partially hydrated/hydroxylated magnesium carbonates and hydroxylated silica species that were mainly in an amorphous state, forming a non-resolved layer on the forsterite surface. At water concentrations above saturation, where forsterite was in contact with both a CO2-saturated aqueous fluid and a water-saturated scCO2 fluid, solid reaction products were magnesite (MgCO3) and an amorphous polymerized SiO2 dominated by Q4, and to a lesser extent by Q3 silica coordination. Formation of these phases implies H2O initially bound in precursor hydrated/hydroxylated reaction products was liberated, inducing further reaction. Hence, for a given fluid/mineral ratio there is a water threshold above which a significant portion of the water serves in a catalytic role where more extensive carbonation reaction occurs. Defining the role of water, even in low water content environments, is therefore critical to determining the long term impact of CO2 reactivity in the subsurface.

  7. Assessment of supercritical fluids for drug analysis.

    PubMed

    Messer, D C; Taylor, L T; Moore, W N; Weiser, W E

    1993-12-01

    Supercritical fluid (SF) CO2 is receiving a great deal of interest in the scientific and engineering community as a replacement for toxic organic solvents. Analytical chemists employ large quantities of organic solvents during preparation of the sample for analysis. The application of SF extraction with CO2 and modified CO2 to the isolation of active drug components and metabolites from various pharmaceutical and biological matrices is reviewed. Studies are described that deal with spiked drugs in animal feed, residual solvent in drug formulations, and active ingredients in over-the-counter products. The experimental challenges to implementing this technology for trace analysis are discussed. While much of the impetus for working with SFs is prompted by regulatory issues, it would appear that SFs afford the analyst a better-cheaper-faster-safer way of performing drug analysis. PMID:8122298

  8. Supercritical or compressed CO2 as a stimulus for tuning surfactant aggregations.

    PubMed

    Zhang, Jianling; Han, Buxing

    2013-02-19

    surfactant aggregation. We can adjust the aggregation behaviors continuously by pressure and can easily remove CO(2) without contaminating the product, and the method is environmentally benign. We can explain the mechanisms for these effects on surfactant aggregation in terms of molecular interactions. These studies expand the areas of colloid and interface science, supercritical fluid science and technology, and chemical thermodynamics. We hope that the work will influence other fundamental and applied research in these areas. PMID:23106121

  9. An investigation of supercritical-CO2 copper electroplating parameters for application in TSV chips

    NASA Astrophysics Data System (ADS)

    Chuang, Ho-Chiao; Lai, Wei-Hong; Sanchez, Jorge

    2015-01-01

    This study uses supercritical electroplating for the filling of through silicon vias (TSVs) in chips. The present study utilizes the inductively coupled plasma reactive ion etching (ICP RIE) process technique to etch the TSVs and discusses different supercritical-CO2 electroplating parameters, such as the supercritical pressure, the electroplating current density’s effect on the TSV Cu pillar filling time, the I-V curve, the electrical resistance and the hermeticity. In addition, the results for all the tests mentioned above have been compared to results from traditional electroplating techniques. For the testing, we will first discuss the hermeticity of the TSV Cu pillars, using a helium leaking test apparatus to assess the vacuum sealing of the fabricated TSV Cu pillars. In addition, this study also conducts tests for the electrical properties, which include the measurement of the electrical resistance of the TSV at both ends in the horizontal direction, followed by the passing of a high current (10 A, due to probe limitations) to check if the TSV can withstand it without burnout. Finally, the TSV is cut in half in cross-section to observe the filling of Cu pillars by the supercritical electroplating and check for voids. The important characteristic of this study is the use of the supercritical electroplating process without the addition of any surfactants to aid the filling of the TSVs, but by taking advantage of the high permeability and low surface tension of supercritical fluids to achieve our goal. The results of this investigation point to a supercritical pressure of 2000 psi and a current density of 3 A dm-2 giving off the best electroplating filling and hermeticity, while also being able to withstand a high current of 10 A, with a relatively short electroplating time of 3 h (when compared to our own traditional dc electroplating).

  10. MALEIC ANHYDRIDE HYDROGENATION OF PD/AL2O3 CATALYST UNDER SUPERCRITICAL CO2 MEDIUM

    EPA Science Inventory

    Hydrogenation of maleic anhydride (MA) to either y-butyrolactone of succinic anhydride over simple Pd/Al2O3 impregnated catalyst in supercritical CO2 medium has been studied at different temperatures and pressures. A comparison of the supercritical CO2 medium reaction with the c...

  11. In Situ Infrared Spectroscopic Study of Forsterite Carbonation in Wet Supercritical CO2

    SciTech Connect

    Loring, John S.; Thompson, Christopher J.; Wang, Zheming; Joly, Alan G.; Sklarew, Deborah S.; Schaef, Herbert T.; Ilton, Eugene S.; Rosso, Kevin M.; Felmy, Andrew R.

    2011-07-19

    Carbonation reactions are central to the prospect of CO2 trapping by mineralization in geologic reservoirs. In contrast to the relevant aqueous-mediated reactions, little is known about the propensity for carbonation in the long-term partner fluid: water-containing supercritical carbon dioxide (‘wet’ scCO2). We employed in situ mid-infrared spectroscopy to follow the reaction of a model silicate mineral (forsterite, Mg2SiO4) for 24 hr with wet scCO2 at 50°C and 180 atm, using water concentrations corresponding to 0%, 55%, 95%, and 136% saturation. Results show a dramatic dependence of reactivity on water concentration and the presence of liquid water on the forsterite particles. Exposure to neat scCO2 showed no detectable carbonation reaction. At 55% and 95% water saturation, a liquid-like thin water film was detected on the forsterite particles; less than 1% of the forsterite transformed, mostly within the first 3 hours of exposure to the fluid. At 136% saturation, where an (excess) liquid water film approximately several nanometers thick was intentionally condensed on the forsterite, the carbonation reaction proceeded continuously for 24 hr with 10% to 15% transformation. Our collective results suggest constitutive links between water concentration, water film formation, reaction rate and extent, and reaction products in wet scCO2.

  12. In situ infrared spectroscopic study of forsterite carbonation in wet supercritical CO2.

    PubMed

    Loring, John S; Thompson, Christopher J; Wang, Zheming; Joly, Alan G; Sklarew, Deborah S; Schaef, H Todd; Ilton, Eugene S; Rosso, Kevin M; Felmy, Andrew R

    2011-07-15

    Carbonation reactions are central to the prospect of CO(2) trapping by mineralization in geologic reservoirs. In contrast to the relevant aqueous-mediated reactions, little is known about the propensity for carbonation in the key partner fluid: supercritical carbon dioxide containing dissolved water ("wet" scCO(2)). We employed in situ mid-infrared spectroscopy to follow the reaction of a model silicate mineral (forsterite, Mg(2)SiO(4)) for 24 h with wet scCO(2) at 50 °C and 180 atm. The results show a dramatic dependence of reactivity on water concentration and the presence of liquid water on the forsterite particles. Exposure to neat scCO(2) showed no detectable carbonation reaction. At 47% and 81% water saturation, an Ångstrom-thick liquid-like water film was detected on the forsterite particles and less than 1% of the forsterite transformed. Most of the reaction occurred within the first 3 h of exposure to the fluid. In experiments at 95% saturation and with an excess of water (36% above water saturation), a nanometer-thick water film was detected, and the carbonation reaction proceeded continuously with approximately 2% and 10% conversion, respectively. Our collective results suggest constitutive links between water concentration, water film formation, reaction rate and extent, and reaction products in wet scCO(2). PMID:21699182

  13. Supercritical CO2 extract of Cinnamomum zeylanicum: chemical characterization and antityrosinase activity.

    PubMed

    Marongiu, Bruno; Piras, Alessandra; Porcedda, Silvia; Tuveri, Enrica; Sanjust, Enrico; Meli, Massimo; Sollai, Francesca; Zucca, Paolo; Rescigno, Antonio

    2007-11-28

    The volatile oil of the bark of Cinnamomum zeylanicum was extracted by means of supercritical CO2 fluid extraction in different conditions of pressure and temperature. Its chemical composition was characterized by GC-MS analysis. Nineteen compounds, which in the supercritical extract represented >95% of the oil, were identified. (E)-Cinnamaldehyde (77.1%), (E)-beta-caryophyllene (6.0%), alpha-terpineol (4.4%), and eugenol (3.0%) were found to be the major constituents. The SFE oil of cinnamon was screened for its biological activity about the formation of melanin in vitro. The extract showed antityrosinase activity and was able to reduce the formation of insoluble flakes of melanin from tyrosine. The oil also delayed the browning effect in apple homogenate. (E)-Cinnamaldehyde and eugenol were found to be mainly responsible of this inhibition effect. PMID:17966976

  14. Supercritical fluid reverse micelle separation

    DOEpatents

    Fulton, J.L.; Smith, R.D.

    1993-11-30

    A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W[sub o] that determines the maximum size of the reverse micelles. The maximum ratio W[sub o] of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions. 27 figures.

  15. Supercritical fluid reverse micelle separation

    DOEpatents

    Fulton, John L.; Smith, Richard D.

    1993-01-01

    A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W.sub.o that determines the maximum size of the reverse micelles. The maximum ratio W.sub.o of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions.

  16. An environmentally friendly approach for contaminants removal using supercritical CO2 for remanufacturing industry

    NASA Astrophysics Data System (ADS)

    Liu, Wei-wei; Zhang, Bin; Li, Yan-zeng; He, Yan-ming; Zhang, Hong-chao

    2014-02-01

    The cleaning technology plays an important role in product quality during the remanufacturing processing. Remanufacturing cleaning is among the most demanding steps and is a particularly essential process in remanufacturing. In the meantime, remanufacturing cleaning is often the main source of pollution in the remanufacturing process. During the past decades, supercritical fluids due to their unique properties gained an increasingly attention in many cleaning industries. The supercritical carbon dioxide as a novel cleaning technology for remanufacturing cleaning process is discussed, which can realize cleaning and drying at the same time, promoting a greener solution for remanufacturing industry. In this paper, we reported the experimental results of the effect of some operating parameters. The CO2 at different operating pressures, temperatures and residence time was made to continuously flowing over this. The decontamination rate and amount were monitored and compared. The obtained results show that the optimum parameters were operating temperature and pressure of 60 °C and 20 MPa respectively, to have the highest decontamination rate value at the investigated experimental conditions. In additon, the success of supercritical CO2 cleaning effectively promotes the research for next-generation cleaning methods for remanufacturing industry.

  17. Partitioning of Organic Compounds between Crude Oil and Water under Supercritical CO2 Condition

    NASA Astrophysics Data System (ADS)

    Rod, K. A.; Wang, G.

    2015-12-01

    In recent years depleted oil reservoirs have received special interest as carbon storage reservoirs because of their potential to offset costs through collaboration with enhanced oil recovery projects. Leakage of the injected CO2 may occur either as supercritical CO2 or CO2-saturated (brine) water. The injected supercritical CO2 is a nonpolar solvent that can potentially mobilize the residual oil compounds into supercritical CO2 and brine water through phase partitioning. For detailed risk assessment of CO2 leakage, various models can be used to quantify the mass of organic contaminants transported from carbon storage sites to potential receptors such as potable aquifers, in which the partition coefficients of crude oil hydrocarbons between CO2/crude oil/brines for subsurface CO2 sequestration scenarios are the key parameters controlling the fate and transport of organic contaminants along the CO2 leakage pathways. However, the solubilities of many of the oil organic compounds in brines under supercritical CO2 condition have not been yet fully determined. In this study, we developed a novel method to accurately measure the partitioning of crude oil organic compounds (BTEX, PAHs, etc.) between supercritical CO2 and brines and to study the effects of temperature, pressure, salinity, and compound's cosolvency (solubility enhancement) on the partitioning behavior of oil organic compounds along the various CO2 leakage paths in the subsurface.

  18. LBM simulation for CO2 saturation monitoring from elastic velocity and resistivity: Migration of supercritical CO2 in porous media under several PT conditions

    NASA Astrophysics Data System (ADS)

    Tsuji, T.; Yamabe, H.; Matsuoka, T.

    2012-12-01

    In Carbon dioxide Capture and Storage (CCS), the monitoring of injected CO2 is critical for (1) predicting the risk of CO2 leakage from storage reservoirs, (2) reducing the cost and increasing the efficiency of CO2 injection, (3) reducing the risk of injection-induced seismicity, and (4) reducing the risk of creating new fractures, and hence opening new flow paths in an otherwise low-permeability capping formation. In seismic approaches, the change in seismic velocity derived from time-lapse seismic surveys can be used to evaluate the distribution of injected CO2, because the P-wave velocity decreases dramatically as the CO2 starts to invade the pore space of a rock initially saturated with brine. However, the rate of change decreases considerably when the saturation of CO2 reaches a value of 20% making the estimation of higher saturations a difficult task. Usefulness of resistivity to estimate CO2 saturation in wide porosity range was presented from laboratory experiments; the resistivity value increases with CO2 saturation even in higher saturation range. However, we cannot characterize the CO2 distribution within pore space only from laboratory experiments. The detailed investigation is needed to generate quantitative description of CO2 migration in porous media and to construct relationship between CO2 saturation and field-derived properties (i.e., seismic velocity and electric resistivity) for the quantitative monitoring of injected CO2. In this study, we apply two-phase lattice Boltzmann method (LBM) to the digital rock models, in order to investigate (a) seismic velocity and (b) electric resistivity under several pressure-temperature (PT) conditions. The simulation study has been compared with laboratory experiments. LBM is one of the computational fluid dynamics methods. In this algorithm, fluid as well as supercritical CO2 is represented as aggregation of imaginary fluid particles, then the movement of microscopic and discretized particles is calculated

  19. Lipidomics by Supercritical Fluid Chromatography.

    PubMed

    Laboureur, Laurent; Ollero, Mario; Touboul, David

    2015-01-01

    This review enlightens the role of supercritical fluid chromatography (SFC) in the field of lipid analysis. SFC has been popular in the late 1980s and 1990s before almost disappearing due to the commercial success of liquid chromatography (LC). It is only 20 years later that a regain of interest appeared when new commercial instruments were introduced. As SFC is fully compatible with the injection of extracts in pure organic solvent, this technique is perfectly suitable for lipid analysis and can be coupled with either highly universal (UV or evaporative light scattering) or highly specific (mass spectrometry) detection methods. A short history of the use of supercritical fluids as mobile phase for the separation oflipids will be introduced first. Then, the advantages and drawbacks of SFC are discussed for each class of lipids (fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, prenols, polyketides) defined by the LIPID MAPS consortium. PMID:26090714

  20. Lipidomics by Supercritical Fluid Chromatography

    PubMed Central

    Laboureur, Laurent; Ollero, Mario; Touboul, David

    2015-01-01

    This review enlightens the role of supercritical fluid chromatography (SFC) in the field of lipid analysis. SFC has been popular in the late 1980s and 1990s before almost disappearing due to the commercial success of liquid chromatography (LC). It is only 20 years later that a regain of interest appeared when new commercial instruments were introduced. As SFC is fully compatible with the injection of extracts in pure organic solvent, this technique is perfectly suitable for lipid analysis and can be coupled with either highly universal (UV or evaporative light scattering) or highly specific (mass spectrometry) detection methods. A short history of the use of supercritical fluids as mobile phase for the separation oflipids will be introduced first. Then, the advantages and drawbacks of SFC are discussed for each class of lipids (fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, prenols, polyketides) defined by the LIPID MAPS consortium. PMID:26090714

  1. Diffusion of gaseous and supercritical CO2 through polycarbonate

    NASA Astrophysics Data System (ADS)

    Goodman, Michael; Ozisik, Rahmi

    2013-03-01

    The design of polymeric materials for applications such as separation membranes and nanostructured foams requires prediction of gas transport properties under a wide range of pressures. In the current study, transport of CO2 both in gaseous and supercritical state through samples of polycarbonate at 51 °C and pressures from 15 to 2000 psi was measured using an asymptotic time lag apparatus. Through volumetric calibration, the traditional analysis was extended to yield permeability (P) and solubility (S), in addition to the usual asymptotic diffusivity (Da). Nonlinear least squares fitting to a truncated series solution then provided an alternative measurement of the (transient) diffusivity (Dt), as well as the surface concentration (Co) of adsorbed gas. At 1 atm, Da and Dt were within a factor of 2 from selected handbook values; and with increasing pressure, both exhibited an overall downward trend, consistent with other studies, but an unexpected dropoff occurred between 1350 and 1500 psi. As expected, Co showed an overall increase with pressure, but as with P and S, displayed a peculiar drop between 1350 and 1500 psi. Measurement of Co in polycarbonate has never been done before and constitutes a novel feature of this study. This work was partially supported by DUE-1003574.

  2. Geochemical simulations on CO2-fluid-rock interactions in EGS reservoirs

    NASA Astrophysics Data System (ADS)

    Pan, F.; McPherson, B. J.; Lichtner, P. C.; Kaszuba, J. P.; Lo Re, C.; Karra, S.; Lu, C.; Xu, T.

    2012-12-01

    Supercritical CO2 has been suggested as a heat transmission fluid in Enhanced Geothermal Systems (EGS) reservoirs to improve energy extraction. Understanding the geochemical processes of CO2-fluid-rock interactions in EGS reservoirs is significant important to investigate the performance of energy extraction with CO2 instead of water as a working fluid, carbon sequestration and risk assessment. The objectives of this study: (1) to calibrate and evaluate the kinetic rate constants and specific reactive surface areas of minerals based on the batch experimental data conducted by other researchers (collaborators Kaszuba and Lo Ré at the University of Wyoming); (2) to investigate the effects of CO2-fluid-rock geochemical interactions on the energy extraction efficiency, carbon sequestration, and risk assessment. A series of laboratory experiments were conducted (Lo Ré et al., 2012) to investigate the geochemical reactions among water, fractured granite rocks, and injected supercritical CO2 at elevated temperatures of 250 oC, and pressures of 250-450 bars. The batch simulations were firstly conducted to mimic the laboratory experiments with the calibration of mineral reactive surface areas using TOUGHREACT model and parameter estimation software (PEST). Then, we performed 2-D geochemical modeling to simulate the chemical interactions among CO2, fluids, and rocks at high temperatures and pressures of EGS reservoirs. We further investigated the effects of fluid-rock interactions on the energy extraction, carbon sequestration, and risk assessment with CO2 as a heat transmission fluid instead of water for EGS reservoirs. Results of carbonate mineral precipitations suggested that the CO2 as a working fluid instead of water was favorable for EGS reservoirs on the CO2 sequestration. Our simulations also suggested that the energy extraction could be enhanced using CO2 as the transmission fluid compared to water.

  3. Supercritical CO2 migration in a fractured rock at reservoir conditions

    NASA Astrophysics Data System (ADS)

    Oh, J.; Kim, K.; Han, W.; Kim, T.; Kim, J.; Park, E.

    2012-12-01

    Suitable geological formations should guarantee a long-term safe and reliable storage of the injected supercritical CO2 (scCO2), and thus densely fractured natural reservoirs are reluctant to consider as a candidate formation. Nevertheless, fractures occur in nearly all geological settings and play a major role for fluid flow. A series of core flooding test were performed to investigate the effect of a fracture on supercritical CO2 migration under reservoir conditions. In the experiment, twin samples of Berea sandstone cores were employed which have 20 % porosity and 1.7×10-13 m2 permeability. One of the twin samples was cut through the center in the direction of longitudinal axis in order to induce a single artificial fracture. The other core represents the homogeneous core. During the test, the downstream pressure was maintained at 10 MPa, and the confining pressure was kept at 20 MPa. The temperature was set to be 40 degrees to reflect the 1 km subsurface environment. The CO2-flooding (drainage) tests with brine-saturated core were performed with different injection rates (q) for both the homogeneous and the fractured core. The scCO2 saturation was measured with linear X-ray scanner. While piston-like brine displacement was observed in homogeneous core with minor effects of gravity over-run, the fractured core showed scCO2 displacing brine at fracture zone instantaneously as the injection started. As the injected volume increased, more CO2 intruded the matrix zone. Injection rates lower than a critical value (3ml/min in our conditions) only allowed CO2 displace brine along fractured zone as the built up pressure did not overcome the entry pressure of the matrix zone. In case q = 5 ml/min, the pressure drop across the cores showed 6 kPa and 13 kPa for fractured and homogeneous core, respectively, revealing that fractured reservoir has advantage on injectivity. The storage capacity was estimated by calculating scCO2 mass stored in both the homogeneous and

  4. Seismic signatures of supercritical CO2 injection/drainage within brine saturated sandstone samples

    NASA Astrophysics Data System (ADS)

    Nakagawa, S.; Kneafsey, T. J.; Rees, E. V.

    2011-12-01

    Successful sequestration of CO2 in geological formations requires high-resolution monitoring of injected CO2 location and accurate determination of CO2 saturation in the pore space, typically using seismic methods. Although understanding of the rock physics (relationship between geophysical properties such as seismic velocities and attenuations and the physical characteristics and environmental parameters of rock including porosity and saturation) of partially saturated rock has advanced significantly in recent years, relationships between heterogeneities of rock (both inherent heterogeneity in the rock fabric and structure and distribution of multiple fluid phases in the rock) and its impact on seismic properties are complex and difficult to understand using existing models. Further, most laboratory experiments to date examining the seismic signatures of fluid substitution involving liquid or supercritical (sc-) CO2 have been conducted at ultrasonic frequencies which could result in very different results from field measurements, and also their interpretations are often made assuming sample homogeneity. We present the results of our recent laboratory measurements on the changes in sonic-frequency seismic properties of initially brine saturated sandstone samples during sc-CO2 injection and drainage. High-permeability reference sandstone sample (Berea, ~680 mD) and a medium-permeability (~15 mD) reservoir sandstone used for sequestration (Tuscaloosa formation from Cranfield, Mississippi) were tested. A modified resonant bar method (the Split Hopkinson Resonant Bar method) was used to measure near-1 kHz seismic velocities and attenuations. This method allows us to use small core samples which are typically available from boreholes. Although our measurement frequency was higher than typical field seismic measurements, it is close to the frequencies which have been used for recent cross-hole seismic monitoring of CO2 injection at several sequestration demonstration

  5. Supercritical Fluid Reactions for Coal Processing

    SciTech Connect

    Charles A. Eckert

    1997-11-01

    Exciting opportunities exist for the application of supercritical fluid (SCF) reactions for the pre-treatment of coal. Utilizing reactants which resemble the organic nitrogen containing components of coal, we developed a method to tailor chemical reactions in supercritical fluid solvents for the specific application of coal denitrogenation. The tautomeric equilibrium of a Schiff base was chosen as one model system and was investigated in supercritical ethane and cosolvent modified supercritical ethane. The Diels-Alder reaction of anthracene and 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) was selected as a second model system, and it was investigated in supercritical carbon dioxide.

  6. Biocompatibility of supercritical CO2-treated titanium implants in a rat model.

    PubMed

    Hill, C M; Kang, Q K; Wahl, C; Jimenez, A; Laberge, M; Drews, M; Matthews, M A; An, Y H

    2006-04-01

    Supercritical phase CO2 is a promising method for sterilizing implantable devices and tissue grafts. The goal of this study is to evaluate the biocompatibility of titanium implants sterilized by supercritical phase CO2 in a rat subcutaneous implantation model. At 5 weeks post implantation titanium implants sterilized by supercritical phase CO2 produce a soft tissue reaction that is comparable to other methods of sterilization (steam autoclave, ultraviolet light radiation, ethylene oxide gas, and radio-frequency glow-discharge), as indicated by the thickness and density of the foreign body capsule, although there were some differences on the capillary density. Overall the soft tissue response to the implants was similar among all methods of sterilization, indicating supercritical phase CO2 treatment did not compromise the biocompatibility of the titanium implant. PMID:16705612

  7. Applicability of Supercritical CO2 Speleogenesis to Exo-Planetary Karst Systems

    NASA Astrophysics Data System (ADS)

    Decker, D. D.; Polyak, V. J.; Asmerom, Y.

    2015-10-01

    Supercritical CO2 hypogene speleogenesis and its applications to exo-planetary karst features are discussed. What to look for on the planet's surface to find these types of caves and their possible use is also visited.

  8. PULSE RADIOLYSIS IN SUPERCRITICAL RARE GAS FLUIDS

    SciTech Connect

    HOLROYD,R.

    2007-01-01

    Recently, supercritical fluids have become quite popular in chemical and semiconductor industries for applications in chemical synthesis, extraction, separation processes, and surface cleaning. These applications are based on: the high dissolving power due to density build-up around solute molecules, and the ability to tune the conditions of a supercritical fluid, such as density and temperature, that are most suitable for a particular reaction. The rare gases also possess these properties and have the added advantage of being supercritical at room temperature. Information about the density buildup around both charged and neutral species can be obtained from fundamental studies of volume changes in the reactions of charged species in supercritical fluids. Volume changes are much larger in supercritical fluids than in ordinary solvents because of their higher compressibility. Hopefully basic studies, such as discussed here, of the behavior of charged species in supercritical gases will provide information useful for the utilization of these solvents in industrial applications.

  9. Investigation of Potassium Feldspar Reactivity in Wet Supercritical CO2 by In Situ Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thompson, C.; Widener, C.; Schaef, T.; Loring, J.; McGrail, B. P.

    2014-12-01

    Capture and subsequent storage of CO2 in deep geologic reservoirs is progressively being considered as a viable approach to reduce anthropogenic greenhouse gas emissions. In the long term, injected CO2 may become permanently entrapped as silicate minerals react with CO2 enriched fluids to form stable carbonate minerals. Potassium feldspars are highly abundant in the earth's crust and are present in the caprocks and storage formations of many target reservoirs. While the dissolution kinetics and carbonation reactions of feldspars have been well studied in the aqueous phase, comparatively little work has focused on K-feldspar reactivity in the CO2-rich fluid. In this study, we used in situ infrared spectroscopy to investigate the carbonation reactions of natural microcline samples. Experiments were carried out at 50 °C and 91 bar by circulating dry or wet supercritical CO2 (scCO2) past a thin film of powdered sample. Water concentrations ranged from 0% to 125% relative to saturation, and transmission-mode absorbance spectra were recorded as a function of time for 48 hours. No discernible reaction was detected when the samples were exposed to anhydrous scCO2. However, in fully water-saturated scCO2, a thin film of liquid-like water was observed on the samples' surfaces, and up to 0.6% of the microcline was converted to a carbonate phase. Potassium carbonate is the most likely reaction product, but minor amounts of sodium carbonate and siderite may also have formed from minor sample impurities. The extent of reaction appears to be related to the thickness of the water film and is likely a consequence of the film's ability to solvate and transport ions in the vicinity of the mineral surface. Other features observed in the spectra correspond to microcline dissolution and precipitation of amorphous silica. Implications about the role of water in these reactions and the relative effectiveness of alkali feldspars for mineral trapping of CO2 will be discussed.

  10. Investigation of Plagioclase Reactivity in Wet Supercritical CO2 by In Situ Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thompson, C.; Gauglitz, K.; Loring, J.; Schaef, T.; Miller, Q.; Johnson, K. T.; Wang, Z.; Rosso, K. M.; McGrail, P.

    2013-12-01

    Increasingly, CO2 capture and subsequent storage in deep geologic reservoirs is being implemented as a viable approach for reducing anthropogenic emissions of CO2 into the atmosphere. Several mechanisms may act to secure the injected CO2, including hydrodynamic confinement, dissolution into reservoir fluids, retention of CO2 as a separate phase in pore spaces, and carbonation of reservoir minerals. This latter mechanism is the most permanent, but it requires the presence of reactive minerals and potentially significant amounts of time for the reactions to proceed. Plagioclase feldspars are highly abundant in the earth's crust and are present in the caprocks and storage formations of many target reservoirs. Although the dissolution kinetics and carbonation reactions of feldspars have been well studied in the aqueous phase, comparatively little work has focused on plagioclase reactivity in the CO2-rich fluid at conditions relevant to geologic carbon sequestration. In this study, we used in situ infrared spectroscopy to investigate the carbonation potential of a powdered plagioclase sample similar to labradorite [(Ca,Na)(Al,Si)4O8] that had been isolated from a Hawaiian basalt. Experiments were carried out at 50 °C and 91 bar by circulating a stream of dry or wet supercritical CO2 (scCO2) past a sample overlayer deposited on the window of a high-pressure infrared flow cell. Water concentrations ranged from 0% to 125% relative to saturation, and transmission-mode absorbance spectra were recorded as a function of time for 24 hours. In experiments with excess water, a controlled temperature gradient was used to intentionally condense a film of liquid water on the overlayers' surfaces. No discernible reaction was detected when the samples were exposed to anhydrous scCO2. When water was added, a thin film of liquid-like water was observed on the samples' surfaces, and up to 0.3% of the plagioclase was converted to a carbonate phase. Calcite is the most likely reaction

  11. Characterization of microbe-mineral interaction under supercritical CO2: Possible roles for bacteria during geologic carbon sequestration

    NASA Astrophysics Data System (ADS)

    Freedman, A. J.; Peet, K. C.; Ajo Franklin, J. B.; Ajo-Franklin, C.; Cappuccio, J. A.; Thompson, J. R.

    2011-12-01

    The injection of CO2 into geological formations at quantities necessary to significantly reduce CO2 emissions will represent an environmental perturbation on a continental scale. Evaluation of potential impacts at and below the surface requires a multifaceted approach that includes accurate prediction of how the CO2 behaves after injection. Microbial activity can significantly catalyze dissolution and nucleation of minerals in subsurface environments. However, the extent to which biogeochemical processes may play a role in the fate and transport of CO2 injected into geological formations has remained an open question due to the fact that at temperatures and pressures associated with reservoirs targeted for sequestration CO2 exists as a supercritical fluid (scCO2), which has generally been regarded as a sterilizing agent. To investigate whether microbial activity may mediate mineral trapping of CO2 on post-injection timescales we have developed a model system for incubating the scCO2 tolerant strain Bacillus MIT0214 (Hernandez, et al.) with minerals under scCO2 using a novel CO2 delivery apparatus. Growth of Bacillus strain MIT0214 under scCO2 (37°C at 120 atm) with a suite of index and accessory minerals associated with sandstone injection zone formations occurred at the same rate as cultures that were not exposed to mineral preparations (i.e. albite, quartz, calcite, biotite, bytownite feldspar, olivine and diopside - identified and characterized by XRD and BET). Further characterization of interactions between MIT0214 and each mineral by scanning electron microscopy and energy-dispersive x-ray spectroscopy (SEM-EDAX) sheds light on the nature of microbe-mineral contacts under scCO2 and the extent to which heterotrophic microbial activity can transform minerals under the high pCO2 conditions associated with geologic CO2 sequestration. The ability to study the dynamics of biocatalyzed mineral dissolution, alteration and nucleation (e.g. silicate weathering

  12. Relative permeability hysteresis and capillary trapping characteristics of supercritical CO2/brine systems: An experimental study at reservoir conditions

    NASA Astrophysics Data System (ADS)

    Akbarabadi, Morteza; Piri, Mohammad

    2013-02-01

    We present the results of an experimental study on the effects of hysteresis on capillary trapping and relative permeability of CO2/brine systems at reservoir conditions. We performed thirty unsteady- and steady-state drainage and imbibition full-recirculation flow experiments in three different sandstone rock samples, low- and high-permeability Berea and Nugget sandstones. The experiments were carried out at various flow rates with both supercritical CO2 (scCO2)/brine and gaseous CO2 (gCO2)/brine fluid systems. The unsteady-state experiments were carried out with a wide range of flow rates to establish a broad range of initial brine saturations (Swi). This allowed investigation of the sensitivity of residual trapped CO2 saturation (S) to changes in Swi. The values were successfully compared with those available in the literature. For a given Swi, the trapped scCO2 saturation was less than that of gCO2 in the same sample. This was attributed to brine being less wetting in the presence of scCO2 than in the presence of gCO2. Post-imbibition dissolution of trapped CO2 and formation of dissolution front was also investigated. During the steady-state experiments, scCO2 and brine were co-injected with monotonically increasing or decreasing fractional flows to perform drainage and imbibition processes. We carried out seven sets of steady-state flow tests with various trajectories generating a comprehensive group of relative permeability hysteresis curves. The scanning curves revealed distinct features with potentially important implications for storage of scCO2 in geological formations. For both series of experiments, the ratio of S to initial CO2 saturation (1- Swi) was found to be much higher for low initial CO2 saturations. The results indicate that very promising fractions (about 49 to 83%) of the initial CO2 saturation can be stored through capillary trapping.

  13. Supercritical CO2 Cleaning System for Planetary Protection and Contamination Control Applications

    NASA Technical Reports Server (NTRS)

    Lin, Ying; Zhong, Fang; Aveline, David C.; Anderson, Mark S.

    2012-01-01

    Current spacecraft-compatible cleaning protocols involve a vapor degreaser, liquid sonication, and alcohol wiping. These methods are not very effective in removing live and dead microbes from spacecraft piece parts of slightly complicated geometry, such as tubing and loosely fitted nuts and bolts. Contamination control practices are traditionally focused on cleaning and monitoring of particulate and oily residual. Vapor degreaser and outgassing bakeout have not been proven to be effective in removing some less volatile, hydrophilic biomolecules of significant relevance to life detection. A precision cleaning technology was developed using supercritical CO2 (SCC). SCC is used as both solvent and carrier for removing organic and particulate contaminants. Supercritical fluid, like SCC, is characterized by physical and thermal properties that are between those of the pure liquid and gas phases. The fluid density is a function of the temperature and pressure. Its solvating power can be adjusted by changing the pressure or temperature, or adding a secondary solvent such as alcohol or water. Unlike a regular organic solvent, SCC has higher diffusivities, lower viscosity, and lower surface tension. It readily penetrates porous and fibrous solids and can reach hard-to-reach surfaces of the parts with complex geometry. Importantly, the CO2 solvent does not leave any residue. The results using this new cleaning device demonstrated that both supercritical CO2 with 5% water as a co-solvent can achieve cleanliness levels of 0.01 mg/cm2 or less for contaminants of a wide range of hydrophobicities. Experiments under the same conditions using compressed Martian air mix, which consists of 95% CO2, produced similar cleaning effectiveness on the hydrophobic compounds. The main components of the SCC cleaning system are a high-pressure cleaning vessel, a boil-off vessel located downstream from the cleaning vessel, a syringe-type high-pressure pump, a heat exchanger, and a back pressure

  14. Molecular dynamics investigation of the various atomic force contributions to the interfacial tension at the supercritical CO2-water interface.

    PubMed

    Zhao, Lingling; Lin, Shangchao; Mendenhall, Jonathan D; Yuet, Pak K; Blankschtein, Daniel

    2011-05-19

    Sequestration of carbon dioxide (CO(2)) in deep, geological formations involves the injection of supercritical CO(2) into depleted reservoirs containing fluids such as brine or oil. The interfacial tension (IFT) between supercritical CO(2) and the reservoir fluid is an important contribution to the sequestration efficiency. In turn, the IFT is a complex function of the reservoir fluid phase composition, the molecular structure of each reservoir fluid component, and environmental conditions (i.e., temperature and pressure). Molecular dynamics simulations can be used to probe the dependence of the IFT on these factors, since the IFT can be calculated directly from the simulated atomic forces and velocities at system equilibrium using the mechanical definition of the IFT. Here, we examine the contribution of each type of atomic force to the IFT, including bonded and nonbonded forces, as quantified by the anisotropy of the atomic virial tensor. In particular, we first examine a supercritical CO(2)-pure liquid water interface, at typical reservoir conditions (temperature of 343 K and pressure of 20 MPa), as a reference state against which CO(2)-brine systems can be compared. In this system, we note that the interactions between water molecules and between CO(2) molecules ("self" interactions) contribute positively to the IFT, while the interactions between water and CO(2) molecules ("cross" interactions) contribute negatively to the IFT. We find that the magnitude of the water "self" interactions is the dominant contribution. In terms of specific types of forces, we find that nonbonded electrostatic (QQ), bonded angle-bending, and bonded bond-stretching interactions contribute positively to the IFT, while nonbonded Lennard-Jones (LJ) interactions contribute negatively to the IFT. We also find that the balance between the LJ interactions and the bond-stretching interactions, in particular, plays a significant role in determining the magnitude of the IFT. Using

  15. Investigation of Mineral Transformations in Wet Supercritical CO2 by Electron Microscopy

    SciTech Connect

    Arey, Bruce W.; Kovarik, Libor; Wang, Zheming; Felmy, Andrew R.

    2011-10-10

    The capture and storage of carbon dioxide and other greenhouse gases in deep geologic formations represents one of the most promising options for mitigating the impacts of greenhouse gases on global warming. In this regard, mineral-fluid interactions are of prime importance since such reactions can result in the long term sequestration of CO2 by trapping in mineral phases. Recently it has been recognized that interactions with neat to water-saturated non-aqueous fluids are of prime importance in understanding mineralization reactions since the introduced CO2 is likely to contain water initially or soon after injection and the supercritical CO2 (scCO2) is less dense than the aqueous phase which can result in a buoyant scCO2 plume contacting the isolating caprock. As a result, unraveling the molecular/microscopic mechanisms of mineral transformation in neat to water saturated scCO2 has taken on an added important. In this study, we are examining the interfacial reactions of the olivine mineral forsterite (Mg2SiO4) over a range of water contents up to and including complete water saturation in scCO2. The surface precipitates that form on the reacted forsterite grains are extremely fragile and difficult to experimentally characterize. In order to address this issue we have developed experimental protocols for preparing and imaging electron-transparent samples from fragile structures. These electron-transparent samples are then examined using a combination of STEM/EDX, FIB-TEM, and helium ion microscope (HIM) imaging (Figures 1-3). This combination of capabilities has provided unique insight into the geochemical processes that occur on scCO2 reacted mineral surfaces. The experimental procedures and protocols that have been developed also have useful applications for examining fragile structures on a wide variety of materials. This research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and

  16. SPECTROSCOPY, MODELING AND COMPUTATION OF METAL CHELATE SOLUBILITY IN SUPERCRITICAL CO2

    EPA Science Inventory

    The objectives of this project are to gain a fundamental understanding of the solubility and stability of metal chelates in supercritical CO2. Extraction with CO2 is a excellent way to remove organic compounds from soils, sludges and aqueous solutions and recent research has demo...

  17. Identification of fragile microscopic structures during mineral transformations in wet supercritical CO2.

    PubMed

    Arey, Bruce W; Kovarik, Libor; Qafoku, Odeta; Wang, Zheming; Hess, Nancy J; Felmy, Andrew R

    2013-04-01

    This study examines the nature of highly fragile reaction products that form in low water content supercritical carbon dioxide (scCO2) using a combination of focus ion beam/scanning electron microscopy, confocal Raman spectroscopy, helium ion microscopy (HeIM), and transmission electron microscopy (TEM). HeIM images show these precipitates are fragile rosettes. Using the TEM revealed details on the interfacial structure between the newly formed surface precipitates and the underlying initial solid phases. Detailed microscopy analysis revealed that growth of the precipitates either followed a tip growth mechanism, with precipitates forming directly on the forsterite surface if the initial solid was nonporous (natural forsterite) or growth from the surface of the precipitates, where fluid was conducted through the porous (nanoforsterite) agglomerates to the growth center. Identification of the mechanism of formation of hydrated/hydroxylated magnesium carbonate compound phases is a key factor in unraveling the impact of water recycling on mineral reactivity in low water content scCO2 solutions, which has received a great deal of attention as a result of the potential for CO2 to act as an atmospheric greenhouse gas. Techniques used here to examine these fragile structures are also used to examine a wide range of fragile material surfaces. PMID:23388324

  18. Concentration dependent refractive index of CO2/CH4 mixture in gaseous and supercritical phase.

    PubMed

    Giraudet, C; Marlin, L; Bégué, D; Croccolo, F; Bataller, H

    2016-04-01

    Carbon dioxide (CO2)/methane (CH4) binary mixtures are investigated at pressure values up to 20 MPa at 303 K in order to investigate the pressure dependence of the optical concentration contrast factor, ∂n/∂cP,T, through gaseous and supercritical phase. Refractive index is measured by means of a Michelson interferometer. Refractivities of the mixtures are found in good agreement with Lorentz-Lorenz predictions after density calculations by means of the AGA8-DC92 equation of state. Experimental polarizabilities of pure fluids are compared to quantum calculations of monomers and dimers for each pressure; it results that the quantity of dimers is small in the investigated thermodynamic conditions. Finally, by extending our experimental database with numerical simulations, we evidence that ∂n/∂cP,T presents a critical enhancement similar to heat capacity. PMID:27059567

  19. Concentration dependent refractive index of CO2/CH4 mixture in gaseous and supercritical phase

    NASA Astrophysics Data System (ADS)

    Giraudet, C.; Marlin, L.; Bégué, D.; Croccolo, F.; Bataller, H.

    2016-04-01

    Carbon dioxide (CO2)/methane (CH4) binary mixtures are investigated at pressure values up to 20 MPa at 303 K in order to investigate the pressure dependence of the optical concentration contrast factor, (" separators=" ∂ n / ∂ c ) P , T , through gaseous and supercritical phase. Refractive index is measured by means of a Michelson interferometer. Refractivities of the mixtures are found in good agreement with Lorentz-Lorenz predictions after density calculations by means of the AGA8-DC92 equation of state. Experimental polarizabilities of pure fluids are compared to quantum calculations of monomers and dimers for each pressure; it results that the quantity of dimers is small in the investigated thermodynamic conditions. Finally, by extending our experimental database with numerical simulations, we evidence that (" separators=" ∂ n / ∂ c ) P , T presents a critical enhancement similar to heat capacity.

  20. Effect of impurities on the corrosion behavior of CO2 transmission pipeline steel in supercritical CO2-water environments.

    PubMed

    Choi, Yoon-Seok; Nesic, Srdjan; Young, David

    2010-12-01

    The corrosion property of carbon steel was evaluated using an autoclave under CO(2)-saturated water phase and water-saturated CO(2) phase with impurities (O(2) and SO(2)) at 80 bar CO(2) and 50 °C to simulate the condition of CO(2) transmission pipeline in the carbon capture and storage (CCS) applications. The results showed that the corrosion rate of carbon steel in CO(2)-saturated water was very high and it increased with adding O(2) in the system due to the inhibition effect of O(2) on the formation of protective FeCO(3). It is noteworthy that corrosion took place in the water-saturated CO(2) phase under supercritical condition when no free water is present. The addition of O(2) increased the corrosion rates of carbon steel in water-saturated CO(2) phase. The addition of 0.8 bar SO(2) (1%) in the gas phase dramatically increased the corrosion rate of carbon steel from 0.38 to 5.6 mm/y. This then increased to more than 7 mm/y with addition of both O(2) and SO(2). SO(2) can promote the formation of iron sulfite hydrate (FeSO(3)·3H(2)O) on the steel surface which is less protective than iron carbonate (FeCO(3)), and it is further oxidized to become FeSO(4) and FeOOH when O(2) is present with SO(2) in the CO(2)-rich phase. The corrosion rates of 13Cr steel were very low compared with carbon steel in CO(2)-saturated water environments with O(2), whereas it was as high as carbon steel in a water-saturated CO(2) phase with O(2) and SO(2). PMID:21049923

  1. Electrodeposition of metals from supercritical fluids

    PubMed Central

    Ke, Jie; Su, Wenta; Howdle, Steven M.; George, Michael W.; Cook, David; Perdjon-Abel, Magda; Bartlett, Philip N.; Zhang, Wenjian; Cheng, Fei; Levason, William; Reid, Gillian; Hyde, Jason; Wilson, James; Smith, David C.; Mallik, Kanad; Sazio, Pier

    2009-01-01

    Electrodeposition is a widely used materials-deposition technology with a number of unique features, in particular, the efficient use of starting materials, conformal, and directed coating. The properties of the solvent medium for electrodeposition are critical to the technique's applicability. Supercritical fluids are unique solvents which give a wide range of advantages for chemistry in general, and materials processing in particular. However, a widely applicable approach to electrodeposition from supercritical fluids has not yet been developed. We present here a method that allows electrodeposition of a range of metals from supercritical carbon dioxide, using acetonitrile as a co-solvent and supercritical difluoromethane. This method is based on a careful selection of reagent and supporting electrolyte. There are no obvious barriers preventing this method being applied to deposit a range of materials from many different supercritical fluids. We present the deposition of 3-nm diameter nanowires in mesoporous silica templates using this methodology. PMID:19706479

  2. Geothermal energy production with supercritical fluids

    DOEpatents

    Brown, Donald W.

    2003-12-30

    There has been invented a method for producing geothermal energy using supercritical fluids for creation of the underground reservoir, production of the geothermal energy, and for heat transport. Underground reservoirs are created by pumping a supercritical fluid such as carbon dioxide into a formation to fracture the rock. Once the reservoir is formed, the same supercritical fluid is allowed to heat up and expand, then is pumped out of the reservoir to transfer the heat to a surface power generating plant or other application.

  3. Design and Analysis of an Axial Bypass Compressor Blade in a Supercritical CO2 Gas Turbine

    NASA Astrophysics Data System (ADS)

    Ishizuka, Takao; Muto, Yasushi; Aritomi, Masanori; Tsuzuki, Nobuyoshi; Kikura, Hiroshige

    A supercritical carbon dioxide gas turbine can generate power at a high cycle thermal efficiency, even at modest temperatures of 500-550°C. Consequently, a more reliable and economically advantageous power generation system is achieved by coupling with a Na-cooled fast reactor. This paper mainly describes the bypass compressor (a key component) design and thermal hydraulic analysis using CFD (with FLUENT code). Fluid conditions of the bypass compressor are determined by the cycle calculation of this system. Aerodynamic design was conducted using the loss model described by Cohen et al., which enables the use of several stages while providing total adiabatic efficiency of 21 and 87%, respectivly. Blade shapes were prepared based on flow angles and chord length obtained for the aerodynamic design. In the CFD analysis, the calculated value of the mass flow rate for each stage was adjusted to that of the design. The value of the design outlet pressure was reached at stage No. 16, which is fewer stages than that for design, No. 21. The difference between these stage numbers is attributed to the three-dimensional effect in design. If these effects are eliminated, then the design calculation yields an almost identical number of stages. Therefore, it was concluded that the existing design method is applicable to the supercritical CO2 bypass compressor. Furthermore, CFD analysis appears to be an effective aerodynamic design tool, but these conclusions should be verified experimentally.

  4. Mechanism of extreme ultraviolet photoresist development with a supercritical CO2 compatible salt.

    PubMed

    Zweber, Amy E; Wagner, Mark; DeYoung, James; Carbonell, Ruben G

    2009-06-01

    The mechanism of developing an extreme ultraviolet (EUV) commercial photoresist with supercritical carbon dioxide (scCO2) and a CO2 compatible salt (CCS) solution was studied. The cloud point of CCS in CO2 and the pressure at which the photoresist dissolves in CCS/scCO2 were determined for temperatures between 35 and 50 degrees C. For this temperature range, it was found that the CCS cloud point ranges between 11.2 and 16.1 MPa, while the photoresist dissolution point ranges from 15.5 to 21.3 MPa. The kinetics of the CCS/scCO2 development was modeled using a simplified rate equation, where the rate-limiting steps were photoresist dissolution and mass transfer. The effects of temperature, mass transfer, pressure, and CCS concentration on photoresist removal rate were further explored experimentally using a high-pressure quartz crystal microbalance (QCM). Increasing temperature (35-50 degrees C) at a constant fluid density of 0.896 g/mL was found to increase the removal rate following an Arrhenius behavior with a photoresist dissolution energy of activation, Ea, equal to 79.0 kJ/mol. The removal was zero order in CCS concentration, signifying photoresist phase transfer, photoresist mass transfer, or both were rate limiting. Mass transfer studies showed that circulation enhanced the photoresist removal rate, but that the mass transfer coefficient was independent of temperature from 35 degrees C to 50 degrees C. In pressure studies, increasing pressure (27.6-34.5 MPa) at a constant temperature of 40 degrees C increased the removal rate by enhancing the fluid density, but at 50 degrees C increasing pressure had little effect on the removal rate. When the total CCS concentration was in large global excess over the number of Bronsted acid groups in the polymer (2400:1 at 5 mM CCS concentration), the mass of photoresist removed varied linearly with time. At lower CCS concentrations but still in global excess of the number of Bronsted acid groups, the photoresist removal

  5. Lattice Boltzmann simulations of supercritical CO2-water drainage displacement in porous media: CO2 saturation and displacement mechanism.

    PubMed

    Yamabe, Hirotatsu; Tsuji, Takeshi; Liang, Yunfeng; Matsuoka, Toshifumi

    2015-01-01

    CO2 geosequestration in deep aquifers requires the displacement of water (wetting phase) from the porous media by supercritical CO2 (nonwetting phase). However, the interfacial instabilities, such as viscous and capillary fingerings, develop during the drainage displacement. Moreover, the burstlike Haines jump often occurs under conditions of low capillary number. To study these interfacial instabilities, we performed lattice Boltzmann simulations of CO2-water drainage displacement in a 3D synthetic granular rock model at a fixed viscosity ratio and at various capillary numbers. The capillary numbers are varied by changing injection pressure, which induces changes in flow velocity. It was observed that the viscous fingering was dominant at high injection pressures, whereas the crossover of viscous and capillary fingerings was observed, accompanied by Haines jumps, at low injection pressures. The Haines jumps flowing forward caused a significant drop of CO2 saturation, whereas Haines jumps flowing backward caused an increase of CO2 saturation (per injection depth). We demonstrated that the pore-scale Haines jumps remarkably influenced the flow path and therefore equilibrium CO2 saturation in crossover domain, which is in turn related to the storage efficiency in the field-scale geosequestration. The results can improve our understandings of the storage efficiency by the effects of pore-scale displacement phenomena. PMID:25427299

  6. Pore-scale Evolution of Supercritical CO2 within Bentheimer Sandstone during Multiple Drainage-Imbibition Cycles

    NASA Astrophysics Data System (ADS)

    Herring, A. L.; Andersson, L.; Wildenschild, D.

    2014-12-01

    Geologic CO2 sequestration has been proposed as a climate change mitigation strategy to limit emissions of CO2 to the atmosphere from large fossil-fuel burning CO2 point sources; however, there are concerns associated with the long-term stability of a mobile subsurface CO2 plume. The large-scale movement of subsurface supercritical CO2 (scCO2) can be prevented via capillary trapping, wherein scCO2 is immobilized in the subsurface by capillary interactions between the solid surface, resident brine, and scCO2. Capillary trapping occurs in two steps: first, the porous medium undergoes drainage as scCO2 is injected into the system; then, wetting fluid re-enters the medium in an imbibition process, isolating small bubbles of scCO2 in the pore bodies of the medium. There are many empirical models which predict capillary trapping for a single drainage-imbibition cycle; however, in an engineered CO2 sequestration project, it is possible to implement cyclic scCO2-water injections in a water-alternating-gas (WAG) injection scheme in which the system may undergo multiple CO2 injections to potentially increase the trapping efficiency of scCO2. We present experimental results of multiple drainage-imbibition cycles of scCO2 and 1:6 by mass potassium iodide (KI) brine within Bentheimer sandstone. Capillary (differential) pressure and absolute pressures for each phase were continuously measured throughout each flow process, which is a unique feature of our experimental system. Experiments were conducted at a working pressure of 8.3 MPa (1200 PSI) and 40oC, and synchrotron x-ray computed microtomography (x-ray CMT) images were collected of the drainage and imbibition process endpoints at a resolution of 3.19 μm at the Advanced Photon Source at Argonne National Laboratory. The evolution of the connectivity, topology, morphology, and capillary trapping of scCO2 phase is analyzed as a function of capillary pressure, scCO2 saturation, and sample history. Preliminary results suggest

  7. Scaling considerations for a multi-megawatt class supercritical CO2 brayton cycle and commercialization.

    SciTech Connect

    Fleming, Darryn D.; Holschuh, Thomas Vernon,; Conboy, Thomas M.; Pasch, James Jay; Wright, Steven Alan; Rochau, Gary Eugene; Fuller, Robert Lynn

    2013-11-01

    Small-scale supercritical CO2 demonstration loops are successful at identifying the important technical issues that one must face in order to scale up to larger power levels. The Sandia National Laboratories supercritical CO2 Brayton cycle test loops are identifying technical needs to scale the technology to commercial power levels such as 10 MWe. The small size of the Sandia 1 MWth loop has demonstration of the split flow loop efficiency and effectiveness of the Printed Circuit Heat Exchangers (PCHXs) leading to the design of a fully recuperated, split flow, supercritical CO2 Brayton cycle demonstration system. However, there were many problems that were encountered, such as high rotational speeds in the units. Additionally, the turbomachinery in the test loops need to identify issues concerning the bearings, seals, thermal boundaries, and motor controller problems in order to be proved a reliable power source in the 300 kWe range. Although these issues were anticipated in smaller demonstration units, commercially scaled hardware would eliminate these problems caused by high rotational speeds at small scale. The economic viability and development of the future scalable 10 MWe solely depends on the interest of DOE and private industry. The Intellectual Property collected by Sandia proves that the ~10 MWe supercritical CO2 power conversion loop to be very beneficial when coupled to a 20 MWth heat source (either solar, geothermal, fossil, or nuclear). This paper will identify a commercialization plan, as well as, a roadmap from the simple 1 MWth supercritical CO2 development loop to a power producing 10 MWe supercritical CO2 Brayton loop.

  8. In Situ Molecular Spectroscopic Evidence for CO2 Intercalation into Montmorillonite in Supercritical Carbon Dioxide

    SciTech Connect

    Loring, John S.; Schaef, Herbert T.; Turcu, Romulus VF; Thompson, Christopher J.; Miller, Quin RS; Martin, Paul F.; Hu, Jian Z.; Hoyt, David W.; Qafoku, Odeta; Ilton, Eugene S.; Felmy, Andrew R.; Rosso, Kevin M.

    2012-04-25

    The interaction of anhydrous supercritical CO2 (scCO2) with both kaolinite and ~1W (i.e. close to but less than one layer of hydration) calcium-saturated montmorillonite was investigated under conditions relevant to geologic carbon sequestration (50 °C and 90 bar). The CO2 molecular environment was probed in situ using a combination of three novel high-pressure techniques: X-ray diffraction, magic angle spinning nuclear magnetic resonance spectroscopy and attenuated total reflection infrared spectroscopy. We report the first direct evidence that the expansion of montmorillonite under scCO2 conditions is due to CO2 migration into the interlayer. Intercalated CO2 molecules are rotationally constrained and do not appear to react with waters to form bicarbonate or carbonic acid. In contrast, CO2 does not intercalate into kaolinite. The findings show that predicting the seal integrity of caprock will have complex dependence on clay mineralogy and hydration state.

  9. In situ molecular spectroscopic evidence for CO2 intercalation into montmorillonite in supercritical carbon dioxide.

    PubMed

    Loring, John S; Schaef, Herbert T; Turcu, Romulus V F; Thompson, Christopher J; Miller, Quin R S; Martin, Paul F; Hu, Jianzhi; Hoyt, David W; Qafoku, Odeta; Ilton, Eugene S; Felmy, Andrew R; Rosso, Kevin M

    2012-05-01

    The interaction of anhydrous supercritical CO(2) (scCO(2)) with both kaolinite and ~1W (i.e., close to but less than one layer of hydration) calcium-saturated montmorillonite was investigated under conditions relevant to geologic carbon sequestration (50 °C and 90 bar). The CO(2) molecular environment was probed in situ using a combination of three novel high-pressure techniques: X-ray diffraction, magic angle spinning nuclear magnetic resonance spectroscopy, and attenuated total reflection infrared spectroscopy. We report the first direct evidence that the expansion of montmorillonite under scCO(2) conditions is due to CO(2) migration into the interlayer. Intercalated CO(2) molecules are rotationally constrained and do not appear to react with waters to form bicarbonate or carbonic acid. In contrast, CO(2) does not intercalate into kaolinite. The findings show that predicting the seal integrity of caprock will have complex dependence on clay mineralogy and hydration state. PMID:22533894

  10. A first principles approach to the electronic properties of liquid and supercritical CO2.

    PubMed

    Cabral, Benedito J Costa; Rivelino, Roberto; Coutinho, Kaline; Canuto, Sylvio

    2015-01-14

    The electronic absorption spectra of liquid and supercritical CO2 (scCO2) are investigated by coupling a many-body energy decomposition scheme to configurations generated by Born-Oppenheimer molecular dynamics. A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies were calculated with time dependent density functional theory. A red-shift of ∼ 0.2 eV relative to the gas-phase monomer is observed for the first electronic absorption maximum in liquid and scCO2. The origin of this shift, which is not very dependent on deviations from the linearity of the CO2 molecule, is mainly related to polarization effects. However, the geometry changes of the CO2 monomer induced by thermal effects and intermolecular interactions in condensed phase lead to the appearance of an average monomeric electric dipole moment〈μ〉= 0.26 ± 0.04 D that is practically the same at liquid and supercritical conditions. The predicted average quadrupole moment for both liquid and scCO2 is〈Θ〉= - 5.5 D Å, which is increased by ∼ -0.9 D Å relative to its gas-phase value. The importance of investigating the electronic properties for a better understanding of the role played by CO2 in supercritical solvation is stressed. PMID:25591369

  11. A first principles approach to the electronic properties of liquid and supercritical CO2

    NASA Astrophysics Data System (ADS)

    Cabral, Benedito J. Costa; Rivelino, Roberto; Coutinho, Kaline; Canuto, Sylvio

    2015-01-01

    The electronic absorption spectra of liquid and supercritical CO2 (scCO2) are investigated by coupling a many-body energy decomposition scheme to configurations generated by Born-Oppenheimer molecular dynamics. A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies were calculated with time dependent density functional theory. A red-shift of ˜ 0.2 eV relative to the gas-phase monomer is observed for the first electronic absorption maximum in liquid and scCO2. The origin of this shift, which is not very dependent on deviations from the linearity of the CO2 molecule, is mainly related to polarization effects. However, the geometry changes of the CO2 monomer induced by thermal effects and intermolecular interactions in condensed phase lead to the appearance of an average monomeric electric dipole moment <μ> = 0.26 ± 0.04 D that is practically the same at liquid and supercritical conditions. The predicted average quadrupole moment for both liquid and scCO2 is <Θ> = - 5.5 D Å, which is increased by ˜ -0.9 D Å relative to its gas-phase value. The importance of investigating the electronic properties for a better understanding of the role played by CO2 in supercritical solvation is stressed.

  12. A Procedure for the supercritical fluid extraction of coal samples, with subsequent analysis of extracted hydrocarbons

    USGS Publications Warehouse

    Kolak, Jonathan J.

    2006-01-01

    Introduction: This report provides a detailed, step-by-step procedure for conducting extractions with supercritical carbon dioxide (CO2) using the ISCO SFX220 supercritical fluid extraction system. Protocols for the subsequent separation and analysis of extracted hydrocarbons are also included in this report. These procedures were developed under the auspices of the project 'Assessment of Geologic Reservoirs for Carbon Dioxide Sequestration' (see http://pubs.usgs.gov/fs/fs026-03/fs026-03.pdf) to investigate possible environmental ramifications associated with CO2 storage (sequestration) in geologic reservoirs, such as deep (~1 km below land surface) coal beds. Supercritical CO2 has been used previously to extract contaminants from geologic matrices. Pressure-temperature conditions within deep coal beds may render CO2 supercritical. In this context, the ability of supercritical CO2 to extract contaminants from geologic materials may serve to mobilize noxious compounds from coal, possibly complicating storage efforts. There currently exists little information on the physicochemical interactions between supercritical CO2 and coal in this setting. The procedures described herein were developed to improve the understanding of these interactions and provide insight into the fate of CO2 and contaminants during simulated CO2 injections.

  13. EMPIRICAL METHOD TO PREDICT SOLUBILITY IN SUPERCRITICAL FLUIDS

    EPA Science Inventory

    The ability to predict the solubility of analytes in supercritical fluids is important in understanding supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC). n SFE, an analyte must dissolve in the supercritical solvent before it can be extracted. n SF...

  14. Surfactant/Supercritical Fluid Cleaning of Contaminated Substrates

    NASA Technical Reports Server (NTRS)

    White, Gary L.

    1997-01-01

    CFC's and halogenated hydrocarbon solvents have been the solvents of choice to degrease and otherwise clean precision metal parts to allow proper function. Recent regulations have, however, rendered most of these solvents unacceptable for these purposes. New processes which are being used or which have been proposed to replace these solvents usually either fail to remove water soluble contaminants or produce significant aqueous wastes which must then be disposed of. In this work, a new method for cleaning surfaces will be investigated. Solubility of typical contaminants such as lubricating greases and phosphatizing bath residues will be studied in several surfactant/supercritical fluid solutions. The effect of temperature, pressure, and the composition of the cleaning mixture on the solubility of oily, polar, and ionic contaminants will be investigated. A reverse micellar solution in a supercritical light hydrocarbon solvent will be used to clean samples of industrial wastes. A reverse micellar solution is one where water is dissolved into a non-polar solvent with the aid of a surfactant. The solution will be capable of dissolving both water-soluble contaminants and oil soluble contaminants. Once the contaminants have been dissolved into the solution they will be separated from the light hydrocarbon and precipitated by a relatively small pressure drop and the supercritical solvent will be available for recycle for reuse. The process will be compared to the efficacy of supercritical CO2 cleaning by attempting to clean the same types of substrates and machining wastes with the same contaminants using supercritical CO2. It is anticipated that the supercritical CO2 process will not be capable of removing ionic residues.

  15. Experimental study of crossover from capillary to viscous fingering for supercritical CO2-water displacement in a homogeneous pore network.

    PubMed

    Wang, Ying; Zhang, Changyong; Wei, Ning; Oostrom, Mart; Wietsma, Thomas W; Li, Xiaochun; Bonneville, Alain

    2013-01-01

    Carbon sequestration in saline aquifers involves displacing brine from the pore space by supercritical CO(2) (scCO(2)). The displacement process is considered unstable due to the unfavorable viscosity ratio between the invading scCO(2) and the resident brine. The mechanisms that affect scCO(2)-water displacement under reservoir conditions (41 °C, 9 MPa) were investigated in a homogeneous micromodel. A large range of injection rates, expressed as the dimensionless capillary number (Ca), was studied in two sets of experiments: discontinuous-rate injection, where the micromodel was saturated with water before each injection rate was imposed, and continuous-rate injection, where the rate was increased after quasi-steady conditions were reached for a certain rate. For the discontinuous-rate experiments, capillary fingering and viscous fingering are the dominant mechanisms for low (logCa ≤ -6.61) and high injection rates (logCa ≥ -5.21), respectively. Crossover from capillary to viscous fingering was observed for logCa = -5.91 to -5.21, resulting in a large decrease in scCO(2) saturation. The discontinuous-rate experimental results confirmed the decrease in nonwetting fluid saturation during crossover from capillary to viscous fingering predicted by numerical simulations by Lenormand et al. (J. Fluid Mech.1988, 189, 165-187). Capillary fingering was the dominant mechanism for all injection rates in the continuous-rate experiment, resulting in monotonic increase in scCO(2) saturation. PMID:22676368

  16. Supercritical fluid thermodynamics for coal processing

    SciTech Connect

    van Swol, F. . Dept. of Chemical Engineering); Eckert, C.A. . School of Chemical Engineering)

    1988-09-15

    The main objective of this research is to develop an equation of state that can be used to predict solubilities and tailor supercritical fluid solvents for the extraction and processing of coal. To meet this objective we have implemented a two-sided. approach. First, we expanded the database of model coal compound solubilities in higher temperature fluids, polar fluids, and fluid mixtures systems. Second, the unique solute/solute, solute/cosolvent and solute/solvent intermolecular interactions in supercritical fluid solutions were investigated using spectroscopic techniques. These results increased our understanding of the molecular phenomena that affect solubility in supercritical fluids and were significant in the development of an equation of state that accurately reflects the true molecular makeup of the solution. (VC)

  17. Migration behavior of supercritical and liquid CO2 in a stratified system: Experiments and numerical simulations

    NASA Astrophysics Data System (ADS)

    Oh, Junho; Kim, Kue-Young; Han, Weon Shik; Park, Eungyu; Kim, Jeong-Chan

    2015-10-01

    Multiple scenarios of upward CO2 migration driven by both injection-induced pressure and buoyancy force were investigated in a horizontally and vertically stratified core utilizing a core-flooding system with a 2-D X-ray scanner. Two reservoir-type scenarios were considered: (1) the terrestrial reservoir scenario (10 MPa and 50°C), where CO2 exists in a supercritical state and (2) the deep-sea sediment reservoir scenario (28 MPa and 25°C), where CO2 is stored in the liquid phase. The core-flooding experiments showed a 36% increase in migration rate in the vertical core setting compared with the horizontal setting, indicating the significance of the buoyancy force under the terrestrial reservoir scenario. Under both reservoir conditions, the injected CO2 tended to find a preferential flow path (low capillary entry pressure and high-permeability (high-k) path) and bypass the unfavorable pathways, leaving low CO2 saturation in the low-permeability (low-k) layers. No distinctive fingering was observed as the CO2 moved upward, and the CO2 movement was primarily controlled by media heterogeneity. The CO2 saturation in the low-k layers exhibited a more sensitive response to injection rates, implying that the increase in CO2 injection rates could be more effective in terms of storage capacity in the low-k layers in a stratified reservoir. Under the deep-sea sediment condition, the storage potential of liquid CO2 was more than twice as high as that of supercritical CO2 under the terrestrial reservoir scenario. In the end, multiphase transport simulations were conducted to assess the effects of heterogeneity on the spatial variation of pressure buildup, CO2 saturation, and CO2 flux. Finally, we showed that a high gravity number (Ngr) tended to be more influenced by the heterogeneity of the porous media.

  18. Mineral Carbonation in Wet Supercritical CO2: An in situ High-Pressure Magic Angle Spinning Nuclear Magnetic Resonance Study

    NASA Astrophysics Data System (ADS)

    Turcu, R. V.; Hoyt, D. H.; Sears, J. A.; Rosso, K. M.; Felmy, A. R.; Hu, J. Z.

    2011-12-01

    Understanding the mechanisms and kinetics of mineral carbonation reactions relevant to sequestering carbon dioxide as a supercritical fluid (scCO2) in geologic formations is crucial for accurately predicting long-term storage risks. In situ probes that provide molecular-level information at geologically relevant temperatures and pressures are highly desirable and challenging to develop. Magic angle spinning nuclear magnetic resonance (MAS NMR) is a powerful tool for obtaining detailed molecular structure and dynamics information of a system regardless whether the system is in a solid, a liquid, a gaseous, a supercritical state, or a mixture thereof. However, MAS NMR under scCO2 conditions has never been realized due to the tremendous technical difficulties of achieving and maintaining high pressure within a fast spinning MAS sample rotor. In this work, we report development of a unique high pressure MAS NMR capability capable of handling fluid pressure exceeding 170 bars and temperatures up to 80°C, and its application to mineral carbonation in scCO2 under geologically relevant temperatures and pressures. Mineral carbonation reactions of the magnesium silicate mineral forsterite and the magnesium hydroxide brucite reacted with scCO2 (up to 170 bar) and containing variable content of H2O (at, below, and above saturation in scCO2) were investigated at 50 to 70°C. In situ 13C MAS NMR spectra show peaks corresponding to the reactants, intermediates, and the magnesium carbonation products in a single spectrum. For example, Figure 1 shows the reaction dynamics, i.e., the formation and conversion of reaction intermediates, i.e., HCO3- and nesquehonite, to magnesite as a function of time at 70°C. This capability offers a significant advantage over traditional ex situ 13C MAS experiments on similar systems, where, for example, CO2 and HCO3- are not directly observable.

  19. Materials, Turbomachinery and Heat Exchangers for Supercritical CO2 Systems

    SciTech Connect

    Anderson, Mark; Nellis, Greg; Corradini, Michael

    2012-10-19

    The objective of this project is to produce the necessary data to evaluate the performance of the supercritical carbon dioxide cycle. The activities include a study of materials compatibility of various alloys at high temperatures, the heat transfer and pressure drop in compact heat exchanger units, and turbomachinery issues, primarily leakage rates through dynamic seals. This experimental work will serve as a test bed for model development and design calculations, and will help define further tests necessary to develop high-efficiency power conversion cycles for use on a variety of reactor designs, including the sodium fast reactor (SFR) and very high-temperature gas reactor (VHTR). The research will be broken into three separate tasks. The first task deals with the analysis of materials related to the high-temperature S-CO{sub 2} Brayton cycle. The most taxing materials issues with regard to the cycle are associated with the high temperatures in the reactor side heat exchanger and in the high-temperature turbine. The system could experience pressures as high as 20MPa and temperatures as high as 650°C. The second task deals with optimization of the heat exchangers required by the S-CO{sub 2} cycle; the S-CO{sub 2} flow passages in these heat exchangers are required whether the cycle is coupled with a VHTR or an SFR. At least three heat exchangers will be required: the pre-cooler before compression, the recuperator, and the heat exchanger that interfaces with the reactor coolant. Each of these heat exchangers is unique and must be optimized separately. The most challenging heat exchanger is likely the pre-cooler, as there is only about a 40°C temperature change but it operates close to the CO{sub 2} critical point, therefore inducing substantial changes in properties. The proposed research will focus on this most challenging component. The third task examines seal leakage through various dynamic seal designs under the conditions expected in the S-CO{sub 2} cycle

  20. CO2-based mixtures as working fluids for geothermal turbines.

    SciTech Connect

    Wright, Steven Alan; Conboy, Thomas M.; Ames, David E.

    2012-01-01

    Sandia National Laboratories is investigating advanced Brayton cycles using supercritical working fluids for application to a variety of heat sources, including geothermal, solar, fossil, and nuclear power. This work is centered on the supercritical CO{sub 2} (S-CO{sub 2}) power conversion cycle, which has the potential for high efficiency in the temperature range of interest for these heat sources and is very compact-a feature likely to reduce capital costs. One promising approach is the use of CO{sub 2}-based supercritical fluid mixtures. The introduction of additives to CO{sub 2} alters the equation of state and the critical point of the resultant mixture. A series of tests was carried out using Sandia's supercritical fluid compression loop that confirmed the ability of different additives to increase or lower the critical point of CO{sub 2}. Testing also demonstrated that, above the modified critical point, these mixtures can be compressed in a turbocompressor as a single-phase homogenous mixture. Comparisons of experimental data to the National Institute of Standards and Technology (NIST) Reference Fluid Thermodynamic and Transport Properties (REFPROP) Standard Reference Database predictions varied depending on the fluid. Although the pressure, density, and temperature (p, {rho}, T) data for all tested fluids matched fairly well to REFPROP in most regions, the critical temperature was often inaccurate. In these cases, outside literature was found to provide further insight and to qualitatively confirm the validity of experimental findings for the present investigation.

  1. Supercritical CO2 Cleaning for Planetary Protection and Contamination Control

    NASA Technical Reports Server (NTRS)

    Lin, Ying; Zhong, Fang; Aveline, David; Anderson, Mark; Chung, Shirley; Mennella, Jerami; Schubert, Wayne

    2010-01-01

    We have designed and built a prototype Supercritical CO? Cleaning (SCC) system at JPL. The key features of the system are: 1) the parts inside a high-pressure vessel can be rotated at high speeds; 2) the same thermodynamic condition is maintained during First-In First-Out flushing to keep solvent power constant; and 3) the boil-off during decompression is induced in a separate vessel downstream. Our goal is to demonstrate SCC's ability to remove trace amounts of microbial and organic contaminants down to parts per billion levels from spacecraft material surfaces for future astrobiology missions. The initial cleaning test results showed that SCC can achieve cleanliness levels of 0.01 microgram/cm(sup 2) or less for hydrophobic contaminants such as dioctyl phthalate and silicone and it is less effective in the removal and inactivation of the hydrophilic bacterial spores as expected. However, with the use of a polar co-solvent, the efficacy may improve dramatically. The same results were obtained using liquid CO?. This opens up the possibility of using subcritical cleaning conditions, which may prove to be more compatible with certain spacecraft hardware.

  2. High-resolution x-ray tomography imaging of supercritical CO2: Investigating capillary trapping under reservoir conditions and addressing wettability alteration

    NASA Astrophysics Data System (ADS)

    Andersson, L.; Herring, A. L.; Newell, D. L.; Carey, B.; Wildenschild, D.

    2013-12-01

    In geological carbon sequestration, CO2 is stored in a supercritical state in subsurface reservoirs. Deep saline aquifers are particularly attractive because of their abundance and potentially large storage volumes. Despite very broad research efforts there are still substantial uncertainties related to the effectiveness of the trapping processes controlling the permanent storage of CO2. After injection of CO2 the saline water (brine) will imbibe back and reoccupy the pore space as the buoyant CO2 moves upwards. Some of the CO2 will remain behind in a trapping mechanism known as capillary trapping that occurs as CO2 bubbles are isolated by the brine inside some of the pore space. The large-scale movement of the trapped CO2 within the brine is thereby prevented. Capillary trapping thus constitutes an important storage mechanism following CO2 injection until subsequent aqueous dissolution and precipitation of carbonate minerals depletes the reservoir of free-phase CO2. We present pressure-saturation curves derived from drainage and imbibition experiments with brine and supercritical CO2 at 1200 PSI and at 36°C for Bentheimer sandstone cores. We compare the supercritical CO2 experiments with ambient pressure and temperature experiments using water and air (supercritical CO2 proxy fluid) for Bentheimer sandstone. The pressure-saturation curves are accompanied with quantitative results on non-wetting phase saturation, topology and connectivity as determined from three-dimensional (3D) images. The 3D data with a resolution of 4.65 μm were derived from high-resolution synchrotron x-ray computed micro-tomography (CMT), collected at the GSECARS beam line 13-BM-D at the Advanced Photon Source, Argonne National Laboratory. Drainage and imbibition experiments, performed under ambient pressure and temperature conditions, indicate that the topology of the non-wetting phase after drainage correlates with the final trapping of the non-wetting phase, after imbibition. Pressure

  3. Using supercritical fluids to refine hydrocarbons

    DOEpatents

    Yarbro, Stephen Lee

    2015-06-09

    A system and method for reactively refining hydrocarbons, such as heavy oils with API gravities of less than 20 degrees and bitumen-like hydrocarbons with viscosities greater than 1000 cp at standard temperature and pressure, using a selected fluid at supercritical conditions. A reaction portion of the system and method delivers lightweight, volatile hydrocarbons to an associated contacting unit which operates in mixed subcritical/supercritical or supercritical modes. Using thermal diffusion, multiphase contact, or a momentum generating pressure gradient, the contacting unit separates the reaction products into portions that are viable for use or sale without further conventional refining and hydro-processing techniques.

  4. The Mechanism of Diopside-Water-Supercritical CO2 Reaction:Relevance to CO2 Sequestration

    NASA Astrophysics Data System (ADS)

    Jiang, D.; Dong, S.; Zhao, L.; Teng, H.

    2013-12-01

    In order to study fundamental mineral carbonation process and reaction extent relevance to CO2 geological sequestration, in situ Raman spectroscopy was used to detect the silicate mineral diopside (CaMgSi2O6)-H2O-scCO2 reaction. In the experiment, diopside bulk grain (0.09g) and grinded powder (0.09g, 200mesh) were put into the sample pool of in situ Raman spectroscopy apparatus in water-saturated condition (10μlH2O: experimental H2O mole fraction in CO2 is 8.1×10-2, solubility of H2O in CO2 at experimental condition is 4.8×10-3), setting at the temperature of 60 degrees centigrade and the pressure of 7.9MPa. Experiment was done following the Lambert-Beer's law:Iv=KLCI0, which shows that Raman intensity(Iv) is proportional to the substance concentration(C)(K, L and I0 are constant in this experiment). The Raman spectrum analysis was performed at the beginning day, day 13, day 28 and day 42 successively. The results indicate that at day 13, a new peak appeared at 1124cm-1 , revealing that in water-saturated scCO2 condition, diopside is converted to huntite (Mg3Ca(CO3)4). The intensity ratio of diopside(1014cm-1) and huntite varies from 4.51:1(beginning) to 2.59:1(day 13) and then to 3.46:1(day 28). However, at day 42, almost no huntite remained in the experiment settings. According to Beer's law, we can conclude that the concentration of huntite increased firstly and then decreased after day 13 until we could not detect it at day 49. The XRD, SEM and FTIR test at day 49 also support the conclusion above. The huntite might form at the very first stage and then got dissolved into HCO3-; further experiments need to be conducted to detect HCO3-. The Raman test on the bulk grain also shows a similar trend as powder, but the reaction of the grain is much slower than powder. Besides, from the test on the grain at day 28, the water film could been detected 100-150μm above the surface of the grain with the thickness of 50-150μm.

  5. Bioanalytical applications using supercritical fluid techniques.

    PubMed

    Ríos, Angel; Zougagh, Mohammed; de Andrés, Fernando

    2010-01-01

    The bioanalytical applications of supercritical fluid techniques, such as supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC), are of increasing interest. The main role of these techniques is in the sample preparation and separation of biologically active compounds, particularly drugs and their metabolites, as well as endogenous compounds. An insight is given into the different types of extracting fluids and modifiers, detectors, stationary phases, mobile phases and collection strategies. A critical discussion is presented on the existing state of the art concerning the applications of SFC and SFE with a specific focus on its advantages and limitations in the bioanalytical field. New developments and the possibilities for routine work in the near future are also covered. PMID:21083113

  6. Supercritical fluid (SCF) technologies: Assessment of applicability to installation restoration processes

    NASA Astrophysics Data System (ADS)

    1994-03-01

    USAEC has conducted an evaluation of supercritical fluid (SCF) technologies for their applicability to treatment of explosives, chlorinated hydrocarbons, and metals in soils, water, and/or waste sludge media. Off-specification explosives and propellants that have traditionally been open burned or openly detonated were also examined. Supercritical fluids are substances which have been heated and compressed to above their critical temperatures and pressures and which possess unique transport and mass transfer properties. Supercritical fluid extraction (SFE) uses the solvating properties of supercritical fluids to extract one or more organic components from a mixture into a supercritical solvent (commonly CO2). The concentrated extract stream may then be recycled, reclaimed, or destroyed by other methods.

  7. Synthesis of higher diamondoids by pulsed laser ablation plasmas in supercritical CO2

    NASA Astrophysics Data System (ADS)

    Nakahara, Sho; Stauss, Sven; Kato, Toru; Sasaki, Takehiko; Terashima, Kazuo

    2011-06-01

    Pulsed laser ablation (wavelength 532 nm; fluence 18 J/cm2; pulse width 7 ns; repetition rate 10 Hz) of highly oriented pyrolytic graphite was conducted in adamantane-dissolved supercritical CO2 with and without cyclohexane as a cosolvent. Micro-Raman spectroscopy of the products revealed the presence of hydrocarbons possessing sp3-hybridized carbons similar to diamond structures. The synthesis of diamantane and other possible diamondoids consisting of up to 12 cages was confirmed by gas chromatography-mass spectrometry. Furthermore, gas chromatography-mass spectrometry measurements of samples before and after pyrolysis treatment indicate the synthesis of the most compact decamantane, namely, superadamantane. It is thought that oxidant species originating from CO2 during pulsed laser ablation might lead to the selective dissociation of C-H bonds, enabling the synthesis of low H/C ratio molecules. Therefore, laser ablation in supercritical CO2 is proposed as a practical method for synthesizing diamondoids.

  8. Structure and Dynamics of Confined Water and CO2 in Clays under Supercritical Conditions

    NASA Astrophysics Data System (ADS)

    Glezakou, V.; Lee, M.; Schaef, T.; Loring, J.; Davidson, C.; McGrail, P.

    2013-12-01

    Carbon dioxide (CO2) driven enhanced gas recovery (EGR) from depleted fractured shale gas reservoirs has the potential for producing economic benefits and providing long term storage options for anthropogenic derived CO2 emissions. However key scientific processes related to CO2:CH4 exchange rates, mineral volume changes, organic mobility, and mineral stability in the presence of acid gas injections are not well understood. In this paper, we conduct atomistic simulations to examine interactions occurring between model clay minerals and supercritical CO2 equilibrated with water or brines to identify parameters controlling adsorption and desorption of gases. Integrated within these simulations are results derived from a set of newly developed experimental techniques designed to characterize physico-chemical reactions at reservoir conditions. In a series of cell optimizations under pressures relevant to sequestration scenarios, molecular simulations within the NVT and NPT ensembles with varying water/CO2 ratios showed a range of interlayer expansion for specific cation-saturated smectites. In conjunction with experimental in situ high pressure x-ray diffraction (HXRD), semi-quantitative concentrations of interlayer H2O and CO2 were established. For example, Ca saturated smectites maintaining sub-single to single hydration states (<1W to 1W), expand approximately 1.7-2.0 Å when exposed to anhydrous supercritical CO2. In contrast, for single to double hydration states (1W-2W), the simulations indicate formation of a quasi-single, metastable state, leading to a reduced interlayer spacing. Partial dehydration of the interlayer spacing while in contact with CO2 is due to a reduction of the interlayer cation coordination number. Structural analysis of the intercalated species shows an increase in the hydrogen bonding between waters during CO2 intercalation coincident with a decrease in the coordination population around the cations. Power spectra reveal rotationally

  9. Theoretical models for supercritical fluid extraction.

    PubMed

    Huang, Zhen; Shi, Xiao-Han; Jiang, Wei-Juan

    2012-08-10

    For the proper design of supercritical fluid extraction processes, it is essential to have a sound knowledge of the mass transfer mechanism of the extraction process and the appropriate mathematical representation. In this paper, the advances and applications of kinetic models for describing supercritical fluid extraction from various solid matrices have been presented. The theoretical models overviewed here include the hot ball diffusion, broken and intact cell, shrinking core and some relatively simple models. Mathematical representations of these models have been in detail interpreted as well as their assumptions, parameter identifications and application examples. Extraction process of the analyte solute from the solid matrix by means of supercritical fluid includes the dissolution of the analyte from the solid, the analyte diffusion in the matrix and its transport to the bulk supercritical fluid. Mechanisms involved in a mass transfer model are discussed in terms of external mass transfer resistance, internal mass transfer resistance, solute-solid interactions and axial dispersion. The correlations of the external mass transfer coefficient and axial dispersion coefficient with certain dimensionless numbers are also discussed. Among these models, the broken and intact cell model seems to be the most relevant mathematical model as it is able to provide realistic description of the plant material structure for better understanding the mass-transfer kinetics and thus it has been widely employed for modeling supercritical fluid extraction of natural matters. PMID:22560346

  10. The influence of water and supercritical CO2 on the failure behavior of chalk

    NASA Astrophysics Data System (ADS)

    Liteanu, E.; Spiers, C. J.; de Bresser, J. H. P.

    2013-06-01

    Reduction of compressive strength by injection of water into chalk is a well-known mechanism responsible for increased compaction in chalk reservoirs. This raises the question of whether such effects might be enhanced in the context of long-term storage of CO2 or of CO2 injection for enhanced oil and gas recovery (EOR/EGR) purposes. Therefore, data regarding the effect of supercritical CO2 on the mechanical behavior of chalk are needed. The effect of supercritical CO2 on the short-term failure behavior of wet chalk was accordingly investigated by means of conventional triaxial deformation experiments, performed on Maastrichtian chalk cores under dry conditions, in the presence of saturated chalk solution and using CO2-saturated solution at temperatures simulating reservoir conditions (20-80 °C) and effective confining pressures up to 7 MPa. Increasing temperature from 20 to 80 °C did not show any significant effects on the strength of the dry samples. Addition of aqueous solution to the samples led to drastic weakening of the chalk, the effect being more pronounced at high effective confining pressures (Peff > 3 MPa). Addition of 10 MPa supercritical CO2 to wet samples did not produce any significant additional effect in comparison with the wet samples. All samples showed a yield strength envelope characterized by shear failure at low effective mean stresses giving way to a compaction cap at high mean stresses. The weakening effect of aqueous solution was explained in terms of a reduction in frictional resistance of the material, due to water-enhanced grain-contact cracking, and perhaps pressure solution, with a possible contribution by disjoining pressure effects caused by water adsorption. While CO2 does not seem to reduce short-term failure strength of wet chalk, processes such as intergranular pressure solution have to be considered for assessing mechanical stability of chalk in the context of long-term CO2 storage or EOR/EGR operations.

  11. Optical emission spectroscopy and shadowgraph imaging of pulsed laser plasmas generated in gaseous, liquid and supercritical CO2

    NASA Astrophysics Data System (ADS)

    Kato, Toru; Takizawa, Yoshihiko; Stauss, Sven; Baba, Motoyoshi; Suemoto, Tohru; Terashima, Kazuo

    2012-10-01

    Pulsed laser ablation (PLA) in liquids has attracted a lot of attention due to its potential for the synthesis of a wide range of nanomaterials. Contrary to PLA in vacuum, in liquids the plasma plume is confined due to the high density of the medium. This restricts the diffusion of active species and leads to rapid quenching, which limits particle growth. Compared to liquids, supercritical fluids (SCFs) possess superior transport properties and PLA in SCFs has been used for realizing chemical synthesis of nanomaterials such as diamondoids. We have investigated the dynamics of PLA (laser: Nd-YAG, wavelength 532 nm; pulse width 7 ns; frequency 10 Hz; target: carbon, nickel) in gaseous (0.1-6 MPa), liquid and supercritical CO2 (Tcrit: 304.1 K, Pcrit: 7.38 MPa). From shadowgraphs of PLA taken in gaseous, liquid and supercritical CO2, images of PLA in SCF showed characteristics similar to that of PLA in liquid. Compared to PLA in the gaseous and liquid states, optical emission spectra in SCF revealed enhanced interactions between plasma and solvent species, especially near the critical point. Owing to the high density fluctuation near the critical point, PLA in SCF is expected to lead to a better control of the synthesis of diamondoids and other nanomaterials.

  12. Hydraulic fracture characterization resulting from low-viscosity fluid injection: Implications for CO2 sequestration

    NASA Astrophysics Data System (ADS)

    Burbey, T. J.; Zhou, X.

    2013-12-01

    The initiation of hydraulic fractures during CO2 sequestration can be either engineered or induced unintentionally. Some fractures may be desirable such as horizontal fractures that can facilitate fluid injection and migration; whereas some fractures may be unfavorable if the fractures tend to extend vertically above a certain limit, thus creating a potential leaking condition. Historically, carbon dioxide as a liquefied gas has been used in oil and gas field stimulation since the early1960s because it eliminates formation damage and residual fluids. Carbon dioxide injection is considered to be one of the most effective technologies for improving oil recovery from hard-to-extract oil reserves because CO2 is effective in penetrating the formation due to its high diffusivity, while the rock associated with petroleum-containing formations is generally porous. However, low viscosity and high compressibility fluids such as CO2 exhibit different effects on the hydraulic fracture initiation/propagation behavior in comparison with high viscosity and low compressibility fluids. Laboratory tests show that viscous fluids tend to generate thick and planar cracks with few branches, while low viscosity fluids tend to generate narrow and wavelike cracks with many secondary branches. A numerical comparison between water and supercritical CO2-like fluid has been made to investigate the influence of fluids to fracture propagation behavior. Simulation results indicate that the pore pressure fields are very different for different pore fluids even when the initial field conditions and injection schemes (rate and time) are kept the same. Thin fluids with properties of supercritical CO2 will create relatively thin and much shorter fractures in comparison to fluids exhibiting properties of water under similar injection schemes. Two significant times are recognized during fracture propagation. One is the time at which a crack ceases opening, and he other is the time at which a crack

  13. Laboratory-scale interaction between CO2-rich brine and limestone and sandstone under supercritical CO2 conditions

    NASA Astrophysics Data System (ADS)

    Garcia-Rios, Maria; Cama, Jordi; Luquot, Linda; Soler, Josep

    2014-05-01

    A test site for a prospective CO2 geological storage is situated in Hontomín (Burgos, northern Spain) with a reservoir rock that is composed of limestone (calcite) and sandstone (66 wt.% calcite, 28 wt.% quartz and 6 wt.% microcline). During and after CO2 injection, the resulting CO2-rich acid brine will likely promote the dissolution of carbonate minerals (calcite) and aluminosilicates (microcline). Since the reservoir Hontomín brine contains sulfate, gypsum (or anhydrite at depth) may precipitate. These coupled dissolution and precipitation reactions may induce changes in porosity and pore structure of the repository rocks. Percolations experiments with mechanically fractured cores (8.6 mm in diameter and 18 mm length) were performed under CO2 supercritical conditions (Pfluid = 150 bar; pCO2 ≡ 90 bar and T = 60 ºC) in order to evaluate and quantify variations in fracture permeability, preferential path formation and fracture volume. The brine sulfate content and the flow rate were varied. Regarding limestone, as the synthetic brines circulated through the fracture, the fracture permeability initially increased slowly, to thereafter increase rapidly. This change was due to a localized dissolution process (wormhole formation) along the core that occurred regardless gypsum precipitation. Nonetheless, the originated fracture volume in the sulfate-rich brine experiments was a factor of two smaller than that in sulfate-free brine experiments. Also, an increase in flow rate from 0.2 to 60 mL/h increased the volume of both dissolved calcite and precipitated gypsum. Regarding sandstone, permeability increased gradually with time. Nonetheless, this increase was not always continuous due to eventual fracture clogging. Formation of wormholes was observed. Acknowledgements This study was financed by CIUDEN (Ciudad de la Energía), the Compostilla OXYCFB300 project and the PANACEA project (European Community's Seventh Framework Programme FP7/2007-2013 under grant

  14. Solubility of caffeine from green tea in supercritical CO2: a theoretical and empirical approach.

    PubMed

    Gadkari, Pravin Vasantrao; Balaraman, Manohar

    2015-12-01

    Decaffeination of fresh green tea was carried out with supercritical CO2 in the presence of ethanol as co-solvent. The solubility of caffeine in supercritical CO2 varied from 44.19 × 10(-6) to 149.55 × 10(-6) (mole fraction) over a pressure and temperature range of 15 to 35 MPa and 313 to 333 K, respectively. The maximum solubility of caffeine was obtained at 25 MPa and 323 K. Experimental solubility data were correlated with the theoretical equation of state models Peng-Robinson (PR), Soave Redlich-Kwong (SRK), and Redlich-Kwong (RK). The RK model had regressed experimental data with 15.52 % average absolute relative deviation (AARD). In contrast, Gordillo empirical model regressed the best to experimental data with only 0.96 % AARD. Under supercritical conditions, solubility of caffeine in tea matrix was lower than the solubility of pure caffeine. Further, solubility of caffeine in supercritical CO2 was compared with solubility of pure caffeine in conventional solvents and a maximum solubility 90 × 10(-3) mol fraction was obtained with chloroform. PMID:26604372

  15. Supercritical fluid mixing in Diesel Engine Applications

    NASA Astrophysics Data System (ADS)

    Bravo, Luis; Ma, Peter; Kurman, Matthew; Tess, Michael; Ihme, Matthias; Kweon, Chol-Bum

    2014-11-01

    A numerical framework for simulating supercritical fluids mixing with large density ratios is presented in the context of diesel sprays. Accurate modeling of real fluid effects on the fuel air mixture formation process is critical in characterizing engine combustion. Recent work (Dahms, 2013) has suggested that liquid fuel enters the chamber in a transcritical state and rapidly evolves to supercritical regime where the interface transitions from a distinct liquid/gas interface into a continuous turbulent mixing layer. In this work, the Peng Robinson EoS is invoked as the real fluid model due to an acceptable compromise between accuracy and computational tractability. Measurements at supercritical conditions are reported from the Constant Pressure Flow (CPF) chamber facility at the Army Research Laboratory. Mie and Schlieren optical spray diagnostics are utilized to provide time resolved liquid and vapor penetration length measurement. The quantitative comparison presented is discussed. Oak Ridge Associated Universities (ORAU).

  16. Control system options and strategies for supercritical CO2 cycles.

    SciTech Connect

    Moisseytsev, A.; Kulesza, K. P.; Sienicki, J. J.; Nuclear Engineering Division; Oregon State Univ.

    2009-06-18

    The Supercritical Carbon Dioxide (S-CO{sub 2}) Brayton Cycle is a promising alternative to Rankine steam cycle and recuperated gas Brayton cycle energy converters for use with Sodium-Cooled Fast Reactors (SFRs), Lead-Cooled Fast Reactors (LFRs), as well as other advanced reactor concepts. The S-CO{sub 2} Brayton Cycle offers higher plant efficiencies than Rankine or recuperated gas Brayton cycles operating at the same liquid metal reactor core outlet temperatures as well as reduced costs or size of key components especially the turbomachinery. A new Plant Dynamics Computer Code has been developed at Argonne National Laboratory for simulation of a S-CO{sub 2} Brayton Cycle energy converter coupled to an autonomous load following liquid metal-cooled fast reactor. The Plant Dynamics code has been applied to investigate the effectiveness of a control strategy for the S-CO{sub 2} Brayton Cycle for the STAR-LM 181 MWe (400 MWt) Lead-Cooled Fast Reactor. The strategy, which involves a combination of control mechanisms, is found to be effective for controlling the S-CO{sub 2} Brayton Cycle over the complete operating range from 0 to 100 % load for a representative set of transient load changes. While the system dynamic analysis of control strategy performance for STARLM is carried out for a S-CO{sub 2} Brayton Cycle energy converter incorporating an axial flow turbine and compressors, investigations of the S-CO{sub 2} Brayton Cycle have identified benefits from the use of centrifugal compressors which offer a wider operating range, greater stability near the critical point, and potentially further cost reductions due to fewer stages than axial flow compressors. Models have been developed at Argonne for the conceptual design and performance analysis of centrifugal compressors for use in the SCO{sub 2} Brayton Cycle. Steady state calculations demonstrate the wider operating range of centrifugal compressors versus axial compressors installed in a S-CO{sub 2} Brayton Cycle as

  17. FINAL REPORT. MICELLE FORMATION AND SURFACE INTERACTIONS IN SUPERCRITICAL CO2: FUNDAMENTAL STUDIES FOR THE EXTRACTION OF ACTINIDES FROM CONTAMINATED SURFACES

    EPA Science Inventory

    The goal of this research was to build the fundamental understanding of microemulsion formation and mobility in supercritical CO2 necessary to develop an innovative extraction system for selectively removing metals (actinides) from contaminated surfaces. Supercritical CO2 has man...

  18. Applications of supercritical fluid extraction and chromatography in forensic science.

    PubMed

    Radcliffe, C; Maguire, K; Lockwood, B

    2000-07-01

    Supercritical fluid technology is a rapidly expanding analytical technique. Here we give a brief insight into the background of supercritical fluid technology and how supercritical fluid extraction and supercritical fluid chromatography work in analysis. The applications of these two techniques in forensic science are known to be important. The main area of forensic use of supercritical fluid technology is in the sample preparation and separation of drugs of abuse particularly opiates, cannabinoids, cocaine and sedatives. Supercritical fluid technology can be used for both time-of-death-related drug analysis and for obtaining information relating to long term drug abuse. We also give a review of the use of supercritical fluids in two other major forensic areas, fingerprinting and the extraction and separation of explosives from both bombing events and gunshot residues. Overall we show that supercritical fluid technology is fast becoming a major part of forensic investigations and that it is an invaluable analysis technique. PMID:10869681

  19. Supercritical Fluid Facilitated Growth of Copper and Aluminum Oxide Nanoparticles

    ERIC Educational Resources Information Center

    Williams, Geoffrey L.; Vohs, Jason K.; Brege, Jonathan J.; Fahlman, Bradley D.

    2005-01-01

    Supercritical fluids (SCFs) possess properties that are intermediate between liquids and gases. The combination of supercritical fluid technology with advanced characterization techniques such as electron microscopy provided a practical and rewarding undergraduate laboratory experiment.

  20. Water Reactivity in the Liquid and Supercritical CO2 Phase: Has Half the Story Been Neglected?

    SciTech Connect

    McGrail, B. Peter; Schaef, Herbert T.; Glezakou, Vassiliki Alexandra; Dang, Liem X.; Owen, Antionette T.

    2009-02-01

    Aqueous-phase mediated chemical reactions with dissolved CO2 have long been considered the principal if not only reactive process supporting mineralization reactions with basalt and other reactive reservoir rocks and caprocks in deep geologic sequestration systems. This is not surprising given the quite high solubility of CO2 in the aqueous phase and ample evidence from natural systems of the reactivity of CO2-charged waters with a variety of silicate minerals. In contrast, comparatively scant attention has been directed at reactivity of water solvated in liquid and supercritical CO2, with the exception of interest in the impacts of water in CO2 on the corrosion of pipeline steels. The results presented in this paper show that the most interesting and important aspects of water reactivity with metal and oxide surfaces of interest in geologic sequestration systems actually occurs in the liquid or supercritical CO2 phase. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  1. Stable carbon isotope ratios as proxies for CO2 migration: An experimental approach with analogue fluids

    NASA Astrophysics Data System (ADS)

    Myrttinen, A.; Becker, V.; Mayer, B.; Barth, J. A.

    2012-12-01

    Stable carbon isotope ratios have proven to be highly sensitive tracers of CO2 migration in the subsurface, provided that the δ13C value of injected CO2 is distinct from that of baseline carbon in the reservoir and in shallow aquifers. This is of great importance for tracing the movement and the fate of injected CO2 in storage reservoirs where fluid and gas samples for chemical and isotope analyses can be obtained. One fundamental aspect that needs to be considered is carbon isotope fractionation between the various dissolved inorganic carbon (DIC) species and sub- or super-critical CO2. Such isotope fractionation may occur at various stages of CO2 migration including, the initial stages of injection during CO2 dissolution; during possible CO2 desiccation in pores; during CO2 migration within the reservoir or even during potential leakage into the near-surface environment. The magnitude and direction of carbon isotope fractionation (1000lnαDIC-CO2) between the DIC species and the injected CO2 depends highly on temperature and pH. At shallow depths, where temperatures are moderate and pH values are typically close to neutral, HCO3- is the dominant form of DIC. Carbon isotope fractionation between CO2 and DIC is therefore expected to reach ~ +10 ‰, resulting in a more positive δ13C value of DIC compared to that of the injected CO2. On the other hand, during injection, elevated temperatures and pH values of below 6 are usually observed. Here, H2CO3 is the dominant form of DIC and carbon isotope fractionation of close to -1 ‰ is expected. However, literature data on isotope fractionation values between H2CO3 and CO2 at temperatures above ˜ 60 °C are limited. In order to investigate the effects of pH and temperature on carbon isotope fractionation at various subsurface conditions, including elevated temperatures and pressures typical for CO2 reservoirs, laboratory experiments with analogue fluids were conducted within the framework of the CO2ISO-LABEL project

  2. Research activities on supercritical fluid science in food biotechnology.

    PubMed

    Khosravi-Darani, Kianoush

    2010-06-01

    This article serves as an overview, introducing the currently popular area of supercritical fluids and their uses in food biotechnology. Within each application, and wherever possible, the basic principles of the technique, as well as a description of the history, instrumentation, methodology, uses, problems encountered, and advantages over the traditional, non-supercritical methods are given. Most current commercial application of the supercritical extraction involve biologically-produced materials; the technique may be particularly relevant to the extraction of biological compounds in cases where there is a requirement for low-temperature processing, high mass-transfer rates, and negligible carrying over of the solvent into the final product. Special applications to food processing include the decaffeination of green coffee beans, the production of hops extracts, the recovery of aromas and flavors from herbs and spices, the extraction and fractionation of edible oils, and the removal of contaminants, among others. New advances, in which the extraction is combined with reaction or crystallization steps, may further increase the attractiveness of supercritical fluids in the bioprocess industries. To develop and establish a novel and effective alternative to heating treatment, the lethal action of high hydrostatic pressure CO(2) on microorganisms, with none or only a minimal heating process, has recently received a great deal of attention. PMID:20544439

  3. Pore-scale supercritical CO2 dissolution and mass transfer under imbibition conditions

    NASA Astrophysics Data System (ADS)

    Chang, Chun; Zhou, Quanlin; Kneafsey, Timothy J.; Oostrom, Mart; Wietsma, Thomas W.; Yu, Qingchun

    2016-06-01

    In modeling of geological carbon storage, dissolution of supercritical CO2 (scCO2) is often assumed to be instantaneous with equilibrium phase partitioning. In contrast, recent core-scale imbibition experiments have shown a prolonged depletion of residual scCO2 by dissolution, implying a non-equilibrium mechanism. In this study, eight pore-scale scCO2 dissolution experiments in a 2D heterogeneous, sandstone-analog micromodel were conducted at supercritical conditions (9 MPa and 40 °C). The micromodel was first saturated with deionized (DI) water and drained by injecting scCO2 to establish a stable scCO2 saturation. DI water was then injected at constant flow rates after scCO2 drainage was completed. High resolution time-lapse images of scCO2 and water distributions were obtained during imbibition and dissolution, aided by a scCO2-soluble fluorescent dye introduced with scCO2 during drainage. These images were used to estimate scCO2 saturations and scCO2 depletion rates. Experimental results show that (1) a time-independent, varying number of water-flow channels are created during imbibition and later dominant dissolution by the random nature of water flow at the micromodel inlet, and (2) a time-dependent number of water-flow channels are created by coupled imbibition and dissolution following completion of dominant imbibition. The number of water-flow paths, constant or transient in nature, greatly affects the overall depletion rate of scCO2 by dissolution. The average mass fraction of dissolved CO2 (dsCO2) in water effluent varies from 0.38% to 2.72% of CO2 solubility, indicating non-equilibrium scCO2 dissolution in the millimeter-scale pore network. In general, the transient depletion rate decreases as trapped, discontinuous scCO2 bubbles and clusters within water-flow paths dissolve, then remains low with dissolution of large bypassed scCO2 clusters at their interfaces with longitudinal water flow, and finally increases with coupled transverse water flow and

  4. H2O-CO2-S fluid triggering the 1991 Mount Pinatubo climactic eruption (Philippines)

    NASA Astrophysics Data System (ADS)

    Borisova, Anastassia Y.; Toutain, Jean-Paul; Dubessy, Jean; Pallister, John; Zwick, Antoine; Salvi, Stefano

    2014-02-01

    The factors that trigger explosive eruptions often remain elusive because of the lack of direct data from representative samples. Here, we report the first micro-Raman spectroscopy measurements of fluid and multiphase inclusions trapped in quartz xenocrysts and microlites from andesitic lavas and basaltic enclaves of the 1991 Mount Pinatubo eruption. Our analyses reveal two-phase H2O-CO2-S inclusions containing a CO2-dominated phase and an aqueous sulfate-bearing liquid phase and, less commonly, anhydrite (CaSO4(solid)). The two fluid phases are low-temperature products of a supercritical H2O-CO2-S fluid which was associated with a hydrous silicate melt prior to eruption. The average density of the CO2 phase is 0.4 ± 0.2 g/cm3 at room temperature, corresponding to a supercritical fluid density of 0.6 ± 0.1 g/cm3 at the conditions of entrapment at 760-1000 °C and up to ˜260 MPa. For the first time, a dense CO2-bearing fluid is reported in Mount Pinatubo volcanic samples. We suggest that this hybrid H2O-CO2-S fluid originated from mixing between sulfur-rich basaltic and hydrous dacitic magmas, as the former was intruded into and interacted with the pre-eruptive Mount Pinatubo dacite magma reservoir, at depths of at least 10 km. Thermodynamic modeling demonstrates that part of the SO2 liberated from the intruded basaltic magma was consumed via interaction with the aqueous fluid-saturated dacitic magma according to the reaction 4SO2 basalt + 4H2Odacite = 3HSO4 - + H2S + 3H+, yielding early Cu-rich sulfides, late abundant anhydrite, and SO4-rich apatites, which are commonly found in the Mount Pinatubo dacites. We suggest that this hybrid H2O-CO2-S fluid played an important role in triggering the 1991 climactic eruption.

  5. Microbial Inactivation by Ultrasound Assisted Supercritical Fluids

    NASA Astrophysics Data System (ADS)

    Benedito, Jose; Ortuño, Carmen; Castillo-Zamudio, Rosa Isela; Mulet, Antonio

    A method combining supercritical carbon dioxide (SC-CO2) and high power ultrasound (HPU) has been developed and tested for microbial/enzyme inactivation purposes, at different process conditions for both liquid and solid matrices. In culture media, using only SC-CO2, the inactivation rate of E. coli and S. cerevisiae increased with pressure and temperature; and the total inactivation (7-8 log-cycles) was attained after 25 and 140 min of SC-CO2 (350 bar, 36 °C) treatment, respectively. Using SC-CO2+HPU, the time for the total inactivation of both microorganisms was reduced to only 1-2 min, at any condition selected. The SC-CO2+HPU inactivation of both microorganisms was slower in juices (avg. 4.9 min) than in culture media (avg. 1.5 min). In solid samples (chicken, turkey ham and dry-cured pork cured ham) treated with SC-CO2 and SC-CO2+HPU, the inactivation rate of E. coli increased with temperature. The application of HPU to the SC-CO2 treatments accelerated the inactivation rate of E. coli and that effect was more pronounced in treatments with isotonic solution surrounding the solid food samples. The application of HPU enhanced the SC-CO2 inactivation mechanisms of microorganisms, generating a vigorous agitation that facilitated the CO2 solubilization and the mass transfer process. The cavitation generated by HPU could damage the cell walls accelerating the extraction of vital constituents and the microbial death. Thus, using the combined technique, reasonable industrial processing times and mild process conditions could be used which could result into a cost reduction and lead to the minimization in the food nutritional and organoleptic changes.

  6. Amphiphile self-assemblies in supercritical CO2 and ionic liquids.

    PubMed

    Zhang, Jianling; Peng, Li; Han, Buxing

    2014-08-28

    Supercritical (sc) CO2 and ionic liquids (ILs) are very attractive green solvents with tunable properties. Using scCO2 and ILs as alternatives of conventional solvents (water and oil) for forming amphiphile self-assemblies has many advantages. For example, the properties and structures of the amphiphile self-assemblies in these solvents can be easily modulated by tuning the properties of solvents; scCO2 has excellent solvation power and mass-transfer characteristics; ILs can dissolve both organic and inorganic substances and their properties are designable to satisfy the requirements of various applications. Therefore, the amphiphile self-assemblies in scCO2 and ILs have attracted considerable attention in recent years. This review describes the advances of using scCO2 or/and ILs as amphiphile self-assembly media in the last decade. The amphiphile self-assemblies in scCO2 and ILs are first reviewed, followed by the discussion on combination of scCO2 and ILs in creating microemulsions or emulsions. Some future directions on the amphiphile self-assemblies in scCO2 and ILs are highlighted. PMID:25000970

  7. Measurement and visualization of supercritical CO2 in dynamic phase transition

    NASA Astrophysics Data System (ADS)

    Ushifusa, Hiroyuki; Inaba, Kazuaki; Sugasawa, Konosuke; Takahashi, Kosuke; Kishimoto, Kikuo

    2015-05-01

    A new experimental device was developed to observe and measure dynamical generations of supercritical CO2 in a chamber. Temperature and pressure were measured locally by thin thermocouple and pressure transducer. The Rayleigh scattering in the chamber was visualized by a high-speed video camera. Heating of the liquid CO2 was conducted by a ceramic heater from the upper or the lower side of the chamber. In the case of heating from the upper side, temperature profile was stable and generates scCO2 slowly within a few seconds. On the other hand, in the case of heating from the lower side, scCO2 was created faster within a second but natural convection and turbulence were observed. Numerical simulations of the scCO2 creation in a chamber were also performed using the COMSOL Multiphysics with a program package for themophysical properties of CO2 called the PROPATH. It showed that scCO2 creation in the heating from the upper side was stable due to the gas-like properties of the scCO2 near the heater. In the case of heating from the lower side, density distribution depended on temperature distribution firstly but after natural convection grows, flow in the chamber became disturbed and the density distribution depended not only on temperature distribution but also on the density fluctuation caused by the convection vortexes. Same tendency was observed in experimental results.

  8. Residual Supercritical CO2 Saturation in an Oil-wet Sandstone: a Pore-scale Analysis

    NASA Astrophysics Data System (ADS)

    Rahman, T.; Lebedev, M.; Barifcani, A.; Iglauer, S.

    2015-12-01

    Residual supercritical CO2 (scCO2) in an oil-wet Bentheimer sandstone was imaged at high 3D resolution (3.4μm)3 with an x-ray micro-computed tomograph (μCT). The residual saturation measured (SCO2,r = 12%) was significantly lower than in an analogue strongly water-wet plug (SCO2,r = 35%). The residual CO2 was split into many small disconnected clusters, and the cluster size distributions followed a power law correlation, similar to those reported for water-wet rock. However, the CO2 was more frequently located in smaller pores than in the analogue water-wet case. On the μCT images we were able to measure scCO2-water interfacial areas and capillary pressures of each CO2 bubble in-situ. These capillary pressures (Pc) showed a distribution function which ranged from -1 MPa to +1 MPa, and peaked at Pc = 0. This variation in Pc will influence the mass transfer process (of CO2 into water) as it changes the chemical potential; but it is clear that the interfacial areas are large and thus provide a good basis for dissolution trapping. Overall we conclude that oil-wet storage rock has a significantly lower capillary trapping capacity, although we still observed residual CO2 at the pore-scale.

  9. Chemicals loading in acetylated bamboo assisted by supercritical CO2 based on phase equilibrium data

    NASA Astrophysics Data System (ADS)

    Silviana, Petermann, M.

    2015-12-01

    Indonesia has a large tropical forest. However, the deforestation still appears annually and vastly. This reason drives a use of bamboo as wood alternative. Recently, there are many modifications of bamboo in order to prolong the shelf life. Unfortunately, the processes need more chemicals and time. Based on wood modification, esterifying of bamboo was undertaken in present of a dense gas, i.e. supercritical CO2. Calculation of chemicals loading referred to ASTM D1413-99 by using the phase equilibrium data at optimum condition by a statistical design. The results showed that the acetylation of bamboo assisted by supercritical CO2 required 14.73 kg acetic anhydride/m3 of bamboo for a treatment of one hour.

  10. Volumetric Properties and Fluid Phase Equilibria of CO2 + H2O

    SciTech Connect

    Capobianco, Ryan; Gruszkiewicz, Miroslaw {Mirek} S; Wesolowski, David J; Cole, David R; Bodnar, Robert

    2013-01-01

    The need for accurate modeling of fluid-mineral processes over wide ranges of temperature, pressure and composition highlighted considerable uncertainties of available property data and equations of state, even for the CO2 + H2O binary system. In particular, the solubility, activity, and ionic dissociation equilibrium data for the CO2-rich phase, which are essential for understanding dissolution/precipitation, fluid-matrix reactions, and solute transport, are uncertain or missing. In this paper we report the results of a new experimental study of volumetric and phase equilibrium properties of CO2 + H2O, to be followed by measurements for bulk and confined multicomponent fluid mixtures. Mixture densities were measured by vibrating tube densimetry (VTD) over the entire composition range at T = 200 and 250 C and P = 20, 40, 60, and 80 MPa. Initial analysis of the mutual solubilities, determined from volumetric data, shows good agreement with earlier results for the aqueous phase, but finds that the data of Takenouchi and Kennedy (1964) significantly overestimated the solubility of water in supercritical CO2 (by a factor of more than two at 200 C). Resolving this well-known discrepancy will have a direct impact on the accuracy of predictive modeling of CO2 injection in geothermal reservoirs and geological carbon sequestration through improved equations of state, needed for calibration of predictive molecular-scale models and large-scale reactive transport simulations.

  11. Ideality contours and thermodynamic regularities in supercritical molecular fluids

    NASA Astrophysics Data System (ADS)

    Desgranges, Caroline; Margo, Abigail; Delhommelle, Jerome

    2016-08-01

    Using Expanded Wang-Landau simulations, we calculate the ideality contours for 3 molecular fluids (SF6, CO2 and H2O). We analyze how the increase in polarity, and thus, in the strength of the intermolecular interactions, impacts the contours and thermodynamic regularities. This effect results in the increase in the Boyle and H parameters, that underlie the Zeno line and the curve of ideal enthalpy. Furthermore, a detailed analysis reveals that dipole-dipole interactions lead to much larger enthalpic contributions to the Gibbs free energy. This accounts for the much higher temperatures and pressures that are necessary for supercritical H2O to achieve ideal-like thermodynamic properties.

  12. Solute Nucleation and Growth in Supercritical Fluid Mixtures

    NASA Technical Reports Server (NTRS)

    Smedley, Gregory T.; Wilemski, Gerald; Rawlins, W. Terry; Joshi, Prakash; Oakes, David B.; Durgin, William W.

    1996-01-01

    This research effort is directed toward two primary scientific objectives: (1) to determine the gravitational effect on the measurement of nucleation and growth rates near a critical point and (2) to investigate the nucleation process in supercritical fluids to aid in the evaluation and development of existing theoretical models and practical applications. A nucleation pulse method will be employed for this investigation using a rapid expansion to a supersaturated state that is maintained for approximately 1 ms followed by a rapid recompression to a less supersaturated state that effectively terminates nucleation while permitting growth to continue. Nucleation, which occurs during the initial supersaturated state, is decoupled from growth by producing rapid pressure changes. Thermodynamic analysis, condensation modeling, apparatus design, and optical diagnostic design necessary for the initiation of a theoretical and experimental investigation of naphthalene nucleation from supercritical CO2 have been completed.

  13. Supercritical fluid extraction and processing of foods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Consumers are aware of the processing techniques used to manufacture food and health supplements and are concerned about the impact of those processes on their health and the environment. Processes that use supercritical fluids as an alternative to solvents that are used to extract nutrients and bio...

  14. In-situ Optical Spectroscopy Investigation of Water and Its influence on Forsterite Transformation in Supercritical CO2

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Thompson, C. J.; Joly, A. G.; Sklarew, D. S.; Poindexter, L.; Rosso, K. M.

    2009-12-01

    Carbon capture and sequestration (CCS) from coal/gas-burning power plants is currently viewed as one of the most promising technologies for mitigating green house gas emissions. This strategy involves injection of supercritical CO2 (scCO2) into deep geological formations such as depleted oil and gas reservoirs and deep saline aquifers. The feasibility of this approach and the ultimate fate of the stored CO2 are determined by the interactions between scCO2, various minerals in the rock formations, and the host fluids. Currently, there is only limited knowledge about both the thermodynamic and kinetic aspects of the physical and chemical processes that occur between scCO2 and relevant minerals, such as metal silicates and metal aluminosilicates, and the role of water activity for catalyzing mineral transformation reactions. In this work, we have developed a modular in situ optical spectroscopic platform that integrates a scCO2 generation and manipulation system with an array of optical and laser spectroscopies including UV-visible, IR, Raman and laser fluorescence spectroscopy. We have used the system to study i) the dissolution and quantification of H2O/D2O in scCO2 and ii) interaction between scCO2 and a model metal silicate, forsterite (Mg2SiO4), and the effects of the presence of water under variable pressure, temperature and water content. Our results showed that H2O and D2O have unique IR spectral features over a broad spectral range from 700 cm-1 to ~ 2900 cm-1 in scCO2 and their concentrations are directly proportional to the characteristic IR bands that correspond to their stretching (D2O) and bending frequencies (both D2O and H2O). These bands offer a unique spectroscopic signature useful for qualitative and quantitative analysis of the properties and reactivity of small amounts of H2O in scCO2. CO2 in the presence of D2O showed systematic variations at several vibrational

  15. Caryocar brasiliense supercritical CO2 extract possesses antimicrobial and antioxidant properties useful for personal care products

    PubMed Central

    2014-01-01

    Background The cosmetic and pharmaceutical industries have an increasing interest in replacing synthetic antimicrobials in dermatological products due to increased microbial resistance to conventional antimicrobial agents. Pequi (Caryocar brasiliense) is a native fruit tree of the Brazilian Cerrado, specifically used in cosmetics, in the food industry, and for medicinal purposes. Leishmanicidal and antifungal activities have been reported previously. This study was designed to evaluate the antimicrobial and antioxidant activities of a C. brasiliense extract obtained by supercritical CO2 extraction. Methods The minimum inhibitory concentrations (MICs) against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were determined by the classical microdilution method. Antiseptic activity against these organisms was evaluated by the plate diffusion method. The antioxidant potential of the extract was evaluated using a method based on the oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). The extract’s chemical profile was analyzed for the presence of alkaloids, saponins, anthraquinones, steroids, tannins, flavonoids, and phenolic compounds according to standard colorimetric methods. Results The C. brasiliense supercritical CO2 extract exhibits antimicrobial activity against all bacteria tested. It also possesses antioxidant activity, when compared to a vitamin E standard. Conclusions The C. brasiliense supercritical CO2 extract may be useful for the development of personal care products, primarily for antiseptic skin products that inactivate, reduce, prevent, or arrest the growth of microorganisms with the inherent intent to mitigate or prevent disease as well as products that minimize damage caused by free radicals. PMID:24565304

  16. Supercritical CO2-assisted embossing for studying cell behaviour on microtextured surfaces.

    PubMed

    Fujita, Satoshi; Ono, Daizaburo; Ohshima, Masahiro; Iwata, Hiroo

    2008-12-01

    Recently, cell responses to micro- and nanoscale structures have attracted much attention. Although interesting phenomena have been observed, we have encountered some difficulties in elucidating purely topographical effects on cell behaviour. These problems are partially attributable to the introduction of functional groups and the persistence of chemicals during surface processing. In this study, we introduced supercritical CO(2)-assisted embossing, which plasticizes a polycarbonate plate by dissolving supercritical CO(2) and thus can emboss wide-scale patterns onto the plate at a lower temperature than the polycarbonate glass transition temperature. Uniform micro- and nanopatterned surfaces were observed across the whole area of the polycarbonate plate surfaces. Nickel, fluorine, and nitrogen were not detected on the fabricated surfaces, and the surface carbon-to-oxygen ratios were equivalent to the theoretical ratio (C:O=84.2:15.8) calculated from the polycarbonate molecular structure. Human mesenchymal stem cells were cultured on the fabricated microlens and nanogroove substrata. Cell-adhered areas became smaller on the microlens than on non-treated polycarbonate. Meanwhile, cells aligned along the ridges of nanogrooves with valleys deeper than 90 nm. This supercritical CO(2)-assisted embossing can produce fine substrates for studying the effects of surface topography of synthetic materials on cell behaviours. PMID:18793798

  17. Basalt Reactivity in the Presence of H2O-Saturated Supercritical CO2 Containing Gaseous Sulfur Compounds

    NASA Astrophysics Data System (ADS)

    Schaef, H. T.; McGrail, P.; Owen, A. T.

    2009-12-01

    Future impacts of climate change may be minimized by capture of emissions, primarily CO2 from fossil-fueled electric generating stations and subsequent sequestration in deep geologic formations. Injection of dry liquid CO2 into porous geologic reservoirs for long term storage is expected to eventually form a buoyant water-saturated bubble of supercritical fluid. Depending on purification processes and underground injection control regulations, the injected CO2 also could contain trace compounds associated with flue gas streams (SO2, N2, and O2). Once injected, the scCO2 will absorb water (1500 to 3000 ppmw) until becoming immobilized by reservoir trapping mechanisms. Reactivity of the water-bearing scCO2 with silicate minerals is relatively unknown and could have impacts on long term reservoir seal integrity and trapping by mineralization. To examine the reactivity of H2O-saturated scCO2, basalt experiments were conducted at pressures and temperatures relevant to geologic sequestration. Reaction products differed considerably depending on the gas mixtures used and type of basalt. In the presence of H2O-saturated CO2, the Newark Basin basalt reacted to produce secondary mineralization with needle-like morphologies and chemistries similar to aragonite. Exposing the same basalt to a CO2-H2S mixture (H2O saturated) produced two types of reaction products: carbonates in the form of small discrete nodules or needles and metallic-like circular areas similar in chemistry to pyrite and marcarsite. Tests conducted in the presence of CO2-SO2 produced the most extensive surface reaction products observed during the experiments. Some basalts were completely coated in white precipitate identified as a mixture of gypsum, sulfate bearing minerals (rozenite and melanterite), and a magnesium sulfate compound (MgSO4 ●5H2O). Hawaiian flow top basalts contained extensive reaction products including magnesium sulfate (MgSO4●6H2O), which formed on the large olivine crystals present

  18. Supercritical CO2 foamed polycaprolactone scaffolds for controlled delivery of 5-fluorouracil, nicotinamide and triflusal.

    PubMed

    Salerno, Aurelio; Saurina, Javier; Domingo, Concepción

    2015-12-30

    The manufacture of porous polycaprolactone (PCL) scaffolds containing three different drugs, namely 5-fluorouracil, nicotinamide and triflusal, was investigated in this work with the aim of obtaining bioactive systems with controlled drug delivery capabilities. The scaffolds were prepared by means of a supercritical CO2 (scCO2) foaming technique by optimizing the drug loading process. This was achieved by dissolving the drugs in organic solvents miscible with scCO2 and by mixing these drug/solvent solutions with PCL powder. The as prepared mixtures were further compressed to eliminate air bubbles and finally processed by the scCO2 foaming technique. ScCO2 saturation and foaming conditions were optimized to create the porosity within the samples and to allow for the concomitant removal of the organic solvents. Physical and chemical properties of porous scaffolds, as well as drug content and delivery profiles, were studied by HPLC. The results of this study demonstrated that the composition of the starting PCL/drug/solvent mixtures affected polymer crystallization, scaffold morphology and pore structure features. Furthermore, it was found that drug loading efficiency depended on both initial solution composition and drug solubility in scCO2. Nevertheless, in the case of highly scCO2-soluble drugs, such as triflusal, loading efficiency was improved by adding a proper amount of free drug inside of the pressure vessel. The drug delivery study indicated that release profiles depended mainly upon scaffolds composition and pore structure features. PMID:26570986

  19. Multiphase Compositional Modelling of CO2 Injection Under Sub- and Supercritical Conditions

    NASA Astrophysics Data System (ADS)

    Afanasyev, Andrey

    2013-04-01

    Modelling of CO2-H2O mixture flows in a porous media under subcritical conditions remains a challenging issue for carbon sequestration and possible leakage scenarios. Currently, there is no widely used and generally accepted numerical model that can simulate three-phase flows with both gaseous and liquid CO2-rich phases. We propose a new compositional modelling approach for sub- and supercritical three-phase flows of water, liquid CO2 and gaseous CO2. The new approach is based on the calculation of the thermodynamic potential of the mixture as a function of pressure, total enthalpy and mixture composition and storing it values as a spline table, which is then used for the hydrodynamic simulation. A three-parametric generalisation of the Peng-Robinson equation of state is used to fit the experimental data on CO2-H2O mixture properties. Using the developed approach, we assess several sample problems of CO2 injection in shallow reservoirs for the purpose of testing the model. We provide the simulation results for a simple 1D problem with a homogeneous reservoir and for a more complicated 2D problem with a highly heterogeneous reservoir using data from the 10th SPE comparative project reservoir. We analyse the temperature variations in the reservoir due to the dissolution of CO2 in water and the evaporation of liquid CO2 under subcritical conditions. The interplay of these processes results in a complicated non-monotonic temperature distribution. At different distances from the CO2 injection point, the temperature can either decrease or increase with respect to the reservoir temperature before injection. The main phenomenon responsible for the considerable temperature decline around the CO2 injection point is the liquid CO2 evaporation process. We also consider parallel simulations of supercritical CO2 plume evolution at Johansen formation. Firstly, we consider a test scenario using a simplified geological model. Both the free CO2 phase saturation and the integral

  20. How Do Deep Saline Aquifer Microbial Communities Respond to Supercritical CO2 Injection?

    NASA Astrophysics Data System (ADS)

    Mu, A.; Billman-Jacobe, H.; Boreham, C.; Schacht, U.; Moreau, J. W.

    2011-12-01

    Carbon Capture and Storage (CCS) is currently seen as a viable strategy for mitigating anthropogenic carbon dioxide pollution. The Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) is currently conducting a field experiment in the Otway Basin (Australia) studying residual gas saturation in the water-saturated reservoir of the Paaratte Formation. As part of this study, a suite of pre-CO2 injection water samples were collected from approximately 1400 meters depth (60°C, 13.8 MPa) via an in situ sampling system. The in situ sampling system isolates aquifer water from sources of contamination while maintaining the formation pressure. Whole community DNA was extracted from these samples to investigate the prokaryotic biodiversity of the saline Paaratte aquifer (EC = 1509.6 uS/cm). Bioinformatic analysis of preliminary 16S ribosomal gene data revealed Thermincola, Acinetobacter, Sphingobium, and Dechloromonas amongst the closest related genera to environmental clone sequences obtained from a subset of pre-CO2 injection groundwater samples. Epifluorescent microscopy with 4',6-diamidino-2-phenylindole (DAPI) highlighted an abundance of filamentous cells ranging from 5 to 45 μM. Efforts are currently directed towards utilising a high throughput sequencing approach to capture an exhaustive profile of the microbial diversity of the Paaratte aquifer CO2 injection site, and to understand better the response of in situ microbial populations to the injection of large volumes (e.g. many kilotonnes) of supercritical CO2 (sc-CO2). Sequencing results will be used to direct cultivation efforts towards enrichment of a CO2-tolerant microorganism. Understanding the microbial response to sc-CO2 is an integral aspect of carbon dioxide storage, for which very little information exists in the literature. This study aims to elucidate molecular mechanisms, through genomic and cultivation-based methods, for CO2 tolerance with the prospect of engineering biofilms to enhance

  1. Solid catalyzed isoparaffin alkylation at supercritical fluid and near-supercritical fluid conditions

    DOEpatents

    Ginosar, Daniel M.; Fox, Robert V.; Kong, Peter C.

    2000-01-01

    This invention relates to an improved method for the alkylation reaction of isoparaffins with olefins over solid catalysts including contacting a mixture of an isoparaffin, an olefin and a phase-modifying material with a solid acid catalyst member under alkylation conversion conditions at either supercritical fluid, or near-supercritical fluid conditions, at a temperature and a pressure relative to the critical temperature(T.sub.c) and the critical pressure(P.sub.c) of the reaction mixture. The phase-modifying phase-modifying material is employed to promote the reaction's achievement of either a supercritical fluid state or a near-supercritical state while simultaneously allowing for decreased reaction temperature and longer catalyst life.

  2. MICELLE FORMATION AND SURFACE INTERACTIONS IN SUPERCRITICAL CO2: FUNDAMENTAL STUDIES FOR THE EXTRACTION OF ACTINIDES FROM CONTAMINATED SURFACES

    EPA Science Inventory

    This research seeks to build the fundamental understanding of micelle formation and mobility in supercritical CO2, necessary to develop an innovative phase-transfer extraction system for selectively removing metals (actinides) from contaminated surfaces. We will extract metal ion...

  3. MICELLE FORMATION AND SURFACE INTERACTIONS IN SUPERCRITICAL CO2: FUNDAMENTAL STUDIES FOR THE EXTRACTION OF ACTINIDES FROM CONTAMINATED SURFACES

    EPA Science Inventory

    The goal of this research was to build a fundamental understanding of microemulsion formation and mobility in supercritical CO2 necessary to develop an innovative extraction system for selectively removing metals (actinides) from contaminated surfaces. The goals included (1) stud...

  4. Experimental investigation of supercritical CO2 trapping mechanisms at the Intermediate Laboratory Scale in well-defined heterogeneous porous media

    DOE PAGESBeta

    Trevisan, Luca; Pini, Ronny; Cihan, Abdullah; Birkholzer, Jens T.; Zhou, Quanlin; Illangasekare, Tissa H.

    2014-12-31

    The heterogeneous nature of typical sedimentary formations can play a major role in the propagation of the CO2 plume, eventually dampening the accumulation of mobile phase underneath the caprock. From core flooding experiments, it is also known that contrasts in capillary threshold pressure due to different pore size can affect the flow paths of the invading and displaced fluids and consequently influence the build- up of non-wetting phase (NWP) at interfaces between geological facies. The full characterization of the geologic variability at all relevant scales and the ability to make observations on the spatial and temporal distribution of the migrationmore » and trapping of supercritical CO2 is not feasible from a practical perspective. To provide insight into the impact of well-defined heterogeneous systems on the flow dynamics and trapping efficiency of supercritical CO2 under drainage and imbibition conditions, we present an experimental investigation at the meter scale conducted in synthetic sand reservoirs packed in a quasi-two-dimensional flow-cell. Two immiscible displacement experiments have been performed to observe the preferential entrapment of NWP in simple heterogeneous porous media. The experiments consisted of an injection, a fluid redistribution, and a forced imbibition stages conducted in an uncorrelated permeability field and a homogeneous base case scenario. We adopted x-ray attenuation analysis as a non-destructive technique that allows a precise measurement of phase saturations throughout the entire flow domain. By comparing a homogeneous and a heterogeneous scenario we have identified some important effects that can be attributed to capillary barriers, such as dampened plume advancement, higher non-wetting phase saturations, larger contact area between the injected and displaced phases, and a larger range of non-wetting phase saturations.« less

  5. 3-D loaded scaffolds obtained by supercritical CO2 assisted process

    NASA Astrophysics Data System (ADS)

    Cardea, S.; Reverchon, E.

    2014-08-01

    In this work, a supercritical CO2 (SC-CO2) drying process for the formation of 3-D PVDF-HFP loaded scaffolds was tested. Experiments at pressures ranging between 150 and 250 bar and at temperatures ranging between 35 and 55°C were performed. The PVDF-HFP- acetone-ethanol solution at 15% w/w polymer was selected as the base case. The drug (amoxicillin) concentration was varied from 20 to 30% w/w with respect to PVDF-HFP. SC- CO2 drying process was confirmed to be a valid alternative to generate loaded structures; indeed, scaffolds characterized by nanometric networks (with mean pore diameter of about 300 nm) with a homogeneous drug distribution were obtained. Drug controlled release experiments were also performed and a quasi-zero order release kinetic was observed.

  6. SAXS investigation on aggregation phenomena in supercritical \\chem{CO2}

    NASA Astrophysics Data System (ADS)

    Celso, F. Lo; Triolo, A.; Triolo, F.; Donato, D. I.; Steinhart, M.; Kriechbaum, M.; Amenitsch, H.; Triolo, R.

    2002-06-01

    Synchrotron Small-Angle X-Ray scattering (SAXS) measurements on aggregate formation of a Polyvinyl acetate-b-Perfluoro octyl acrylate (PVAc-b-PFOA) block copolymer in supercritical CO{2} are here reported. Experiments were carried out for a series of different thermodynamic conditions, changing the solvent density by profiling both the pressure at constant temperature and the temperature at constant pressure. This block copolymer and in general fluorocarbon-hydrocarbon di-blocks form aggregates depending on the value of CO{2} density. A sharp transition between monomers dissolved as random coils and micelles characterized by a solvophilic shell and a solvophobic core occurs when the CO{2} density reaches a critical value. Results of critical micellization density (CMD) derived from pressure and temperature ramps experiment along with the comparison with previous SANS results are here reported to give additional experimental support to the solvent density-driven aggregation process.

  7. Geophysical Signatures to Monitor Fluids and Mineralization for CO2 Sequestration in Basalts

    NASA Astrophysics Data System (ADS)

    Otheim, L. T.; Adam, L.; Van Wijk, K.; Batzle, M. L.; Mcling, T. L.; Podgorney, R. K.

    2011-12-01

    Carbon dioxide sequestration in large reservoirs can reduce emissions of this green house gas into the atmosphere. Basalts are promising host rocks due to their volumetric extend, worldwide distribution, and recent observations that CO2-water mixtures react with basalt minerals to precipitate as carbonate minerals, trapping the CO2. The chemical reaction between carbonic acid and minerals rich in calcium, magnesium and iron precipitates carbonates in the pore space. This process would increase the elastic modulus and velocity of the rock. At the same time, the higher compressibility of CO2 over water changes the elastic properties of the rock, decreasing the saturated rock bulk modulus and the P-wave velocity. Reservoirs where the rock properties change as a result of fluid or pressure changes are commonly monitored with seismic methods. Here we present experiments to study the feasibility of monitoring CO2 migration in a reservoir and CO2-rock reactions for a sequestration scenario in basalts. Our goal is to measure the rock's elastic response to mineralization with non-contacting ultrasonic lasers, and the effect of fluid substitution at reservoir conditions at seismic and ultrasonic frequencies. For the fluid substitution experiment we observe changes in the P- and S-wave velocities when saturating the sample with super-critical (sc) CO2, CO2-water mixtures and water alone for different pore and confining pressures. The bulk modulus of the rock is significantly dependent on frequency in the 2~to 106~Hz range, for CO2-water mixtures and pure water saturations. Dry and pure CO2 (sc or gas) do not show a frequency dependence on the modulus. Moreover, the shear wave modulus is not dispersive for either fluid. The frequency dependence of the elastic parameters is related to the attenuation (1/Q) of the rock. We will show the correlation between frequency dependent moduli and attenuation data for the different elastic moduli of the rocks. Three other basalt samples

  8. Remote-Raman spectroscopic study of minerals under supercritical CO2 relevant to Venus exploration.

    PubMed

    Sharma, Shiv K; Misra, Anupam K; Clegg, Samuel M; Barefield, James E; Wiens, Roger C; Acosta, Tayro E; Bates, David E

    2011-10-01

    The authors have utilized a recently developed compact Raman spectrometer equipped with an 85 mm focal length (f/1.8) Nikon camera lens and a custom mini-ICCD detector at the University of Hawaii for measuring remote Raman spectra of minerals under supercritical CO(2) (Venus chamber, ∼102 atm pressure and 423 K) excited with a pulsed 532 nm laser beam of 6 mJ/pulse and 10 Hz. These experiments demonstrate that by focusing a frequency-doubled 532 nm Nd:YAG pulsed laser beam with a 10× beam expander to a 1mm spot on minerals located at 2m inside a Venus chamber, it is possible to measure the remote Raman spectra of anhydrous sulfates, carbonates, and silicate minerals relevant to Venus exploration during daytime or nighttime with 10s integration time. The remote Raman spectra of gypsum, anhydrite, barite, dolomite and siderite contain fingerprint Raman lines along with the Fermi resonance doublet of CO(2). Raman spectra of gypsum revealed dehydration of the mineral with time under supercritical CO(2) at 423 K. Fingerprint Raman lines of olivine, diopside, wollastonite and α-quartz can easily be identified in the spectra of these respective minerals under supercritical CO(2). The results of the present study show that time-resolved remote Raman spectroscopy with a compact Raman spectrometer of moderate resolution equipped with a gated intensified CCD detector and low power laser source could be a potential tool for exploring Venus surface mineralogy both during daytime and nighttime from a lander. PMID:21333587

  9. Processing of Materials for Regenerative Medicine Using Supercritical Fluid Technology.

    PubMed

    García-González, Carlos A; Concheiro, Angel; Alvarez-Lorenzo, Carmen

    2015-07-15

    The increase in the world demand of bone and cartilage replacement therapies urges the development of advanced synthetic scaffolds for regenerative purposes, not only providing mechanical support for tissue formation, but also promoting and guiding the tissue growth. Conventional manufacturing techniques have severe restrictions for designing these upgraded scaffolds, namely, regarding the use of organic solvents, shearing forces, and high operating temperatures. In this context, the use of supercritical fluid technology has emerged as an attractive solution to design solvent-free scaffolds and ingredients for scaffolds under mild processing conditions. The state-of-the-art on the technological endeavors for scaffold production using supercritical fluids is presented in this work with a critical review on the key processing parameters as well as the main advantages and limitations of each technique. A special stress is focused on the strategies suitable for the incorporation of bioactive agents (drugs, bioactive glasses, and growth factors) and the in vitro and in vivo performance of supercritical CO2-processed scaffolds. PMID:25587916

  10. MOLECULAR DESIGN OF COLLOIDS IN SUPERCRITICAL FLUIDS

    SciTech Connect

    Keith P. Johnston

    2009-04-06

    The environmentally benign, non-toxic, non-flammable fluids water and carbon dioxide (CO2) are the two most abundant and inexpensive solvents on earth. Emulsions of these fluids are of interest in many industrial processes, as well as CO2 sequestration and enhanced oil recovery. Until recently, formation of these emulsions required stabilization with fluorinated surfactants, which are expensive and often not environmentally friendly. In this work we overcame this severe limitation by developing a fundamental understanding of the properties of surfactants the CO2-water interface and using this knowledge to design and characterize emulsions stabilized with either hydrocarbon-based surfactants or nanoparticle stabilizers. We also discovered a new concept of electrostatic stabilization for CO2-based emulsions and colloids. Finally, we were able to translate our earlier work on the synthesis of silicon and germanium nanocrystals and nanowires from high temperatures and pressures to lower temperatures and ambient pressure to make the chemistry much more accessible.

  11. Silicate Carbonation in Supercritical CO2 Containing Dissolved H2O: An in situ High Pressure X-Ray Diffraction Study

    SciTech Connect

    Schaef, Herbert T.; Miller, Quin RS; Thompson, Christopher J.; Loring, John S.; Bowden, Mark E.; Arey, Bruce W.; McGrail, B. Peter; Rosso, Kevin M.

    2013-01-01

    Technological advances have been significant in recent years for managing environmentally harmful emissions (mostly CO2) resulting from combustion of fossil fuels. Deep underground geologic formations are emerging as reasonable options for long term storage of CO2 but mechanisms controlling rock and mineral stability in contact with injected supercritical fluids containing water are relatively unknown. In this paper, we discuss mineral transformation reactions occurring between supercritical CO2 containing water and the silicate minerals forsterite (Mg2SiO4), wollastonite (CaSiO3), and enstatite (MgSiO3). This study utilizes newly developed in situ high pressure x-ray diffraction (HXRD) and in situ infra red (IR) to examine mineral transformation reactions. Forsterite and enstatite were selected as they are important minerals present in igneous and mafic rocks and have been the subject of a large number of aqueous dissolution studies that can be compared with non-aqueous fluid tests in this study. Wollastonite, classified as a pyroxenoid (similar to a pyroxene), was chosen as a suitably fast reacting proxy for examining silicate carbonation processes associated with a wet scCO2 fluid as related to geologic carbon sequestration. The experiments were conducted under modest pressures (90 to 160 bar), temperatures between 35° to 70° C, and varying concentrations of dissolved water. Under these conditions scCO2 contains up to 3,500 ppm dissolved water.

  12. Investigation of attractive and repulsive interactions associated with ketones in supercritical CO2, based on Raman spectroscopy and theoretical calculations

    NASA Astrophysics Data System (ADS)

    Kajiya, Daisuke; Saitow, Ken-ichi

    2013-08-01

    Carbonyl compounds are solutes that are highly soluble in supercritical CO2 (scCO2). Their solubility governs the efficiency of chemical reactions, and is significantly increased by changing a chromophore. To effectively use scCO2 as solvent, it is crucial to understand the high solubility of carbonyl compounds, the solvation structure, and the solute-solvent intermolecular interactions. We report Raman spectroscopic data, for three prototypical ketones dissolved in scCO2, and four theoretical analyses. The vibrational Raman spectra of the C=O stretching modes of ketones (acetone, acetophenone, and benzophenone) were measured in scCO2 along the reduced temperature Tr = T/Tc = 1.02 isotherm as a function of the reduced density ρr = ρ/ρc in the range 0.05-1.5. The peak frequencies of the C=O stretching modes shifted toward lower energies as the fluid density increased. The density dependence was analyzed by using perturbed hard-sphere theory, and the shift was decomposed into attractive and repulsive energy components. The attractive energy between the ketones and CO2 was up to nine times higher than the repulsive energy, and its magnitude increased in the following order: acetone < acetophenone < benzophenone. The Mulliken charges of the three solutes and CO2 molecules obtained by using quantum chemistry calculations described the order of the magnitude of the attractive energy and optimized the relative configuration between each solute and CO2. According to theoretical calculations for the dispersion energy, the dipole-induced-dipole interaction energy, and the frequency shift due to their interactions, the experimentally determined attractive energy differences in the three solutes were attributed to the dispersion energies that depended on a chromophore attached to the carbonyl groups. It was found that the major intermolecular interaction with the attractive shift varied from dipole-induced dipole to dispersion depending on the chromophore in the ketones in

  13. Comparative Reactivity Study of Natural Silicate Minerals in Wet Supercritical CO2 By In Situ Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thompson, C.; Schaef, T.; Miller, Q. R.; Loring, J. S.; Wang, Z.; Johnson, K. T.; McGrail, P.

    2012-12-01

    Long-term storage of CO2 in deep geologic reservoirs is one of the strategies being developed and implemented for reducing anthropogenic emissions of CO2 into the atmosphere. Reservoirs containing basalt or peridotite have the potential to permanently entrap the CO2 as silicate minerals react with the CO2 and formation waters to form stable carbonate minerals. Although the relevant reactions have been well studied in the aqueous phase, comparatively little work has focused on silicate mineral reactivity in the CO2-rich fluid containing dissolved water at conditions relevant to geologic carbon sequestration. In this study, we used in situ infrared spectroscopy to investigate the carbonation of naturally occurring samples of San Carlos olivine (Mg2SiO4), Bramble enstatite (MgSiO3), and a Hawaiian picritic basalt rich in olivine. To enhance reactivity, subsamples were micronized to obtain higher surface area materials, in the range of 14 to 23 m2g-1. Experiments were carried out at 50 °C and 91 bar by circulating a stream of dry or wet supercritical CO2 (scCO2) past a sample overlayer deposited on the window of a high-pressure infrared flow cell. Water concentrations ranged from 0% to 135% relative to saturation, and transmission-mode absorbance spectra were recorded as a function of time for 24 hours. In experiments with excess water, a controlled temperature gradient was used to intentionally condense a film of liquid water on the overlayers' surfaces. No discernible reaction was detected when the samples were exposed to dry scCO2. When water was added to the scCO2, a thin film of liquid-like water formed on the surfaces of each sample, followed by spectral evidence of carbonation. The extents of reaction were dependent on both the thickness of the water films and the materials being tested. The thinnest water film was associated with the Bramble enstatite, which also appeared minimally reactive. The Hawaiian picritic basalt was slightly more reactive but contained

  14. Non-catalytic transfer hydrogenation in supercritical CO2 for coal liquefaction

    NASA Astrophysics Data System (ADS)

    Elhussien, Hussien

    This thesis presents the results of the investigation on developing and evaluating a low temperature (<150°C) non - catalytic process using a hydrogen transfer agent (instead of molecu-lar hydrogen) for coal dissolution in supercritical CO2. The main idea behind the thesis was that one hydrogen atom from water and one hydrogen atom from the hydrogen transfer agent (HTA) were used to hydrogenate the coal. The products of coal dissolution were non-polar and polar while the supercritical CO2, which enhanced the rates of hydrogenation and dissolution of the non-polar molecules and removal from the reaction site, was non-polar. The polar modifier (PM) for CO2 was added to the freed to aid in the dissolution and removal of the polar components. The addition of a phase transfer agent (PTA) allowed a seamless transport of the ions and by-product between the aqueous and organic phases. DDAB, used as the PTA, is an effective phase transfer catalyst and showed enhancement to the coal dissolution process. COAL + DH- +H 2O → COAL.H2 + DHO-- This process has a great feature due to the fact that the chemicals were obtained without requir-ing to first convert coal to CO and H2 units as in indirect coal liquefaction. The experiments were conducted in a unique reactor set up that can be connected through two lines. one line to feed the reactor with supercritical CO 2 and the other connected to gas chromatograph. The use of the supercritical CO2 enhanced the solvent option due to the chemical extraction, in addition to the low environmental impact and energy cost. In this thesis the experiment were conducted at five different temperatures from atmos-pheric to 140°C, 3000 - 6000 psi with five component of feed mixture, namely water, HTA, PTA, coal, and PM in semi batch vessels reactor system with a volume of 100 mL. The results show that the chemicals were obtained without requiring to first convert coal to CO and H2 units as in indirect coal liquefaction. The results show that

  15. Pt and Pt-Ru/Carbon Nanotube Nanocomposites Synthesized in Supercritical Fluid as Electrocatalysts for Low-Temperature Fuel Cells

    SciTech Connect

    Lin, Yuehe; Cui, Xiaoli; Wang, Jun; Yen, Clive; Wai, Chien M.

    2006-06-01

    In recent years, the use of supercritical fluids (SCFs) for the synthesis and processing of nanomaterials has proven to be a rapid, direct, and clean approach to develop nanomaterials and nanocomposites. The application of supercritical fluid technology can result in products (and processes) that are cleaner, less expensive, and of higher quality than those that are produced using conventional technologies and solvents. In this work, carbon nanotube (CNT)-supported Pt and Pt-Ru nanoparticles catalysts have been synthesized in supercritical carbon dioxide (scCO2). The experimental results demonstrate that Pt, Pt-Ru/CNT nanocomposites synthesized in supercritical carbon dioxide are effective electrocatalysts for low-temperature fuel cells.

  16. Characteristics of optical emission intensities and bubblelike phenomena induced by laser ablation in supercritical fluids

    NASA Astrophysics Data System (ADS)

    Takada, Noriharu; Machmudah, Siti; Goto, Hiroshi; Wahyudiono; Goto, Motonobu; Sasaki, Koichi

    2014-01-01

    We investigated the characteristics of laser ablation phenomena in supercritical fluids by optical emission and shadowgraph imaging. In comparison with laser ablation in liquid H2O, the optical emission of a laser ablation plasma produced in supercritical H2O had a longer lifetime and a larger transport length. It was found in supercritical CO2 that laser ablation plasmas with bright optical emissions were produced at a mass density of approximately 300 kg/m3. A clear correlation between the optical emission intensity and the density fluctuation was not observed in our experimental results, which were obtained in a regime deviated from the critical point. Bubblelike hollows were observed by shadowgraph imaging in both supercritical H2O and CO2. The dynamics of the bubblelike hollows were different from the dynamics of a cavitation bubble induced by laser ablation in a liquid medium but relatively similar to the dynamics of ambient gas in gas-phase laser ablation.

  17. A study of vortex breakdown in supercritical fluids

    NASA Astrophysics Data System (ADS)

    Crook, Loren C.

    The objective of this thesis is to evaluate the hydrodynamic stability theory of vortex breakdown by examining its presence in a swirling supercritical fluid jet. Supercritical fluids were chosen because they are technologically important, and because their strong density gradients near the critical point provide a self-excitable flow regime where hydrodynamic instabilities should be more easily identified. Computations were developed to provide flow conditions for experimental observation of vortex breakdown and to estimate hydrodynamic flow instabilities prior to testing. The RANS computations of an axial-plus-tangential air swirler were developed and verified as grid-independent and in agreement with experimental results reported in the literature. The computations also produced a correlation of momentum swirl number as a function of mass ratio (tangential/total) for estimating swirl number during experiments. Finally, the computations were extended to simulate supercritical CO2 in an axial-plus-tangential swirler that was compatible with the supercritical injection facility. Three mass flow ratio cases were investigated extensively: no-swirl (0%), low-swirl prior to breakdown (25%), and moderate swirl with breakdown (45%). (The three corresponding momentum swirl numbers for these mass flow ratios were 0.0, 0.30 and 0.80.) These three cases also served as the basis for the experimental portion of the work. Swirling supercritical fluid jets were observed in the injection facility using schlieren imaging for three separate swirl numbers. The Sobel method was used to locate the jet edges. The jets were characterized by their radii, including mean and standard deviation, and spreading angles as functions of swirl number and density ratio (2.3, 2.6, and 5.0). The swirl number was identified as the dominant parameter in determining the spreading angle and jet radius. Vortex breakdown was identified as the jet structure changed from straight edges to curved, signifying

  18. The U-tube: A novel system for acquiring borehole fluid samples from a deep geologic CO2 sequestration experiment

    USGS Publications Warehouse

    Freifeld, B.M.; Trautz, R.C.; Kharaka, Y.K.; Phelps, T.J.; Myer, L.R.; Hovorka, S.D.; Collins, D.J.

    2005-01-01

    A novel system has been deployed to obtain geochemical samples of water and gas, at in situ pressure, during a geologic CO2 sequestration experiment conducted in the Frio brine aquifer in Liberty County, Texas. Project goals required high-frequency recovery of representative and uncontaminated aliquots of a rapidly changing two-phase fluid (supercritical CO2 and brine) fluid from 1.5 km depth. The data sets collected, using both the liquid and gas portions of the downhole samples, provide insights into the coupled hydrogeochemical issues affecting CO2 sequestration in brine-filled formations. While the basic premise underlying the U-tube sampler is not new, the system is unique because careful consideration was given to the processing of the recovered two-phase fluids. In particular, strain gauges mounted beneath the high-pressure surface sample cylinders measured the ratio of recovered brine to supercritical CO2. A quadrupole mass spectrometer provided real-time gas analysis for perfluorocarbon and noble gas tracers that were injected along with the CO2. The U-tube successfully acquired frequent samples, facilitating accurate delineation of the arrival of the CO2 plume, and on-site analysis revealed rapid changes in geochemical conditions. Copyright 2005 by the American Geophysical Union.

  19. The U-tube: A novel system for acquiring borehole fluid samples from a deep geologic CO2 sequestration experiment

    NASA Astrophysics Data System (ADS)

    Freifeld, Barry M.; Trautz, Robert C.; Kharaka, Yousif K.; Phelps, Tommy J.; Myer, Larry R.; Hovorka, Susan D.; Collins, Daniel J.

    2005-10-01

    A novel system has been deployed to obtain geochemical samples of water and gas, at in situ pressure, during a geologic CO2 sequestration experiment conducted in the Frio brine aquifer in Liberty County, Texas. Project goals required high-frequency recovery of representative and uncontaminated aliquots of a rapidly changing two-phase fluid (supercritical CO2 and brine) fluid from 1.5 km depth. The data sets collected, using both the liquid and gas portions of the downhole samples, provide insights into the coupled hydrogeochemical issues affecting CO2 sequestration in brine-filled formations. While the basic premise underlying the U-tube sampler is not new, the system is unique because careful consideration was given to the processing of the recovered two-phase fluids. In particular, strain gauges mounted beneath the high-pressure surface sample cylinders measured the ratio of recovered brine to supercritical CO2. A quadrupole mass spectrometer provided real-time gas analysis for perfluorocarbon and noble gas tracers that were injected along with the CO2. The U-tube successfully acquired frequent samples, facilitating accurate delineation of the arrival of the CO2 plume, and on-site analysis revealed rapid changes in geochemical conditions.

  20. Fayalite Dissolution and Siderite Formation in Water-Saturated Supercritical CO2

    SciTech Connect

    Qafoku, Odeta; Kovarik, Libor; Kukkadapu, Ravi K.; Ilton, Eugene S.; Arey, Bruce W.; Tucek, Jiri; Felmy, Andrew R.

    2012-11-25

    Olivines, a significant constituent of basaltic rocks, have the potential to immobilize permanently CO2 after it is injected in the deep subsurface, due to carbonation reactions occurring between CO2 and the host rock. To investigate the reactions of fayalitic olivine with supercritical CO2 (scCO2) and formation of mineral carbonates, experiments were conducted at temperatures of 35 °C to 80 °C, 90 atm pressure and anoxic conditions. For every temperature, the dissolution of fayalite was examined both in the presence of liquid water and H2O-saturated scCO2. The experiments were conducted in a high pressure batch reactor at reaction time extending up to 85 days. The newly formed products were characterized using a comprehensive suite of bulk and surface characterization techniques X-ray diffraction, Transmission/Emission Mössbauer Spectroscopy, Scanning Electron Microscopy coupled with Focused Ion Beam, and High Resolution Transmission Electron Microscopy. Siderite with rhombohedral morphology was formed at 35 °C, 50 °C, and 80 °C in the presence of liquid water and scCO2. In H2O-saturated scCO2, the formation of siderite was confirmed only at high temperature (80 °C). Characterization of reacted samples in H2O-saturated scCO2 with high resolution TEM indicated that siderite formation initiated inside voids created during the initial steps of fayalite dissolution. Later stages of fayalite dissolution result in the formation of siderite in layered vertical structures, columns or pyramids with a rhombus base morphology.

  1. Experimental study on effects of geologic heterogeneity in enhancing dissolution trapping of supercritical CO2

    NASA Astrophysics Data System (ADS)

    Agartan, Elif; Trevisan, Luca; Cihan, Abdullah; Birkholzer, Jens; Zhou, Quanlin; Illangasekare, Tissa H.

    2015-03-01

    Dissolution trapping is one of the primary mechanisms that enhance the storage security of supercritical carbon dioxide (scCO2) in saline geologic formations. When scCO2 dissolves in formation brine produces an aqueous solution that is denser than formation brine, which leads to convective mixing driven by gravitational instabilities. Convective mixing can enhance the dissolution of CO2 and thus it can contribute to stable trapping of dissolved CO2. However, in the presence of geologic heterogeneities, diffusive mixing may also contribute to dissolution trapping. The effects of heterogeneity on mixing and its contribution to stable trapping are not well understood. The goal of this experimental study is to investigate the effects of geologic heterogeneity on mixing and stable trapping of dissolved CO2. Homogeneous and heterogeneous media experiments were conducted in a two-dimensional test tank with various packing configurations using surrogates for scCO2 (water) and brine (propylene glycol) under ambient pressure and temperature conditions. The results show that the density-driven flow in heterogeneous formations may not always cause significant convective mixing especially in layered systems containing low-permeability zones. In homogeneous formations, density-driven fingering enhances both storage in the deeper parts of the formation and contact between the host rock and dissolved CO2 for the potential mineralization. On the other hand, for layered systems, dissolved CO2 becomes immobilized in low-permeability zones with low-diffusion rates, which reduces the risk of leakage through any fault or fracture. Both cases contribute to the permanence of the dissolved plume in the formation.

  2. Assessment of Supercritical Fluid Extraction Use in Whole Sediment Toxicity Identification Evaluations

    EPA Science Inventory

    In this investigation, supercritical fluid extraction (SFE) with pure CO2 was assessed as a confirmatory tool in Phase III of whole sediment toxicity identification evaluations (TIEs). The SFE procedure was assessed on two reference sediments and three contaminated sediments usi...

  3. Silver nanoparticles generated by pulsed laser ablation in supercritical CO2 medium

    NASA Astrophysics Data System (ADS)

    Machmudah, Siti; Sato, Takayuki; Wahyudiono; Sasaki, Mitsuru; Goto, Motonobu

    2012-03-01

    Pulsed laser ablation (PLA) has been widely employed in industrial and biological applications and in other fields. The environmental conditions in which PLA is conducted are important parameters that affect both the solid particle cloud and the deposition produced by the plume. In this work, the generation of nanoparticles (NPs) has been developed by performing PLA of silver (Ag) plates in a supercritical CO2 medium. Ag NPs were successfully generated by allowing the selective generation of clusters. Laser ablation was performed with an excitation wavelength of 532 nm under various pressures and temperatures of CO2 medium. On the basis of the experimental result, both surface of the irradiated Ag plate and structure of Ag NPs were significantly affected by the changes in supercritical CO2 pressure and temperature. With increasing irradiation pressure, plume deposited in the surrounding crater created by the ablation was clearly observed. In Field Emission Scanning Electron Microscopy (FE-SEM) the image of the generated Ag NPs on the silicon wafer and the morphology of Ag particles were basically a sphere-like structure. Ag particles contain NPs with large-varied diameter ranging from 5 nm to 1.2 μm. The bigger Ag NPs melted during the ablation process and then ejected smaller spherical Ag NPs, which formed nanoclusters attached on the molten Ag NPs. The smaller Ag NPs were also formed around the bigger Ag NPs. Based on the results, this new method can also be used to obtain advanced nano-structured materials.

  4. Application of supercritical CO2 and ionic liquids for the preparation of fluorinated nanocomposites.

    PubMed

    Livi, Sébastien; Duchet-Rumeau, Jannick; Gérard, Jean-François

    2012-03-01

    This work is focused on the tailoring of dispersions of layered silicates, such as MICA SOMASIF (ME-100) within a fluoride matrix (polytetrafluoroethylene) through two strategies: the physicochemical interactions between filler and matrix and the processing of materials. The interactions in these complex systems are modified by new environmentally friendly thermally stable surfactants. The ionic liquids used are based on alkyltriphenyl phosphonium and perfluorinated alkylpyridinium cations. The influences of the cation-anion combination and functionalization were investigated. The use of the supercritical carbon dioxide (ScCO(2)) as a solvent is relevant to generate structuring within the material based on ionic liquid phase separation. The tunability of ionic liquids and their combination with the supercritical carbon dioxide enables to design materials with optimized thermal and mechanical properties. PMID:22204975

  5. Microstructural Response of Variably Hydrated Ca-Rich Montmorillonite to Supercritical CO2

    SciTech Connect

    Lee, Mal Soon; McGrail, B. Peter; Glezakou, Vassiliki Alexandra

    2014-08-05

    We report on ab initio molecular dynamics simulations of Ca-rich montmorillonite systems, in different hydration states in the presence of supercritical CO2. Analysis of the molecular trajectories provides estimates of the relative H2O:CO2 ratio per interspatial cation. The vibrational density of states in direct comparison with dipole moment derived IR spectra for these systems provide unique signatures that can used to follow molecular transformation. In a co-sequestration scenario, these signatures could be used to identify the chemical state and fate of Sulfur compounds. Interpretation of CO2 asymmetric stretch shift is given based on a detailed analysis of scCO2 structure and intermolecular interactions of the intercalated species. Based on our simulations, smectites with higher charge interlayer cations at sub-single to single hydration states should be more efficient in capturing CO2, while maintaining caprock integrity. This research would not have been possible without the support of the office of Fossil Energy, Department of Energy. The computational resources were made available through a user proposal of the EMSL User facility, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  6. Geoelectrical characterization of carbonate and silicate porous media in the presence of supercritical CO2-water flow

    NASA Astrophysics Data System (ADS)

    Abidoye, Luqman Kolawole; Das, Diganta Bhusan

    2015-10-01

    The relative permittivity (εr) and the electrical conductivity (σ) of porous media are known to be functions of water saturation (S). As such, their measurements can be useful in effective characterisations and monitoring of geological carbon sequestration using geoelectrical measurement techniques. In this work, the effects of pressure, temperature and salt concentration on bulk εr-S and σ-S relationships were investigated for carbonate (limestone) and silicate porous media (both unconsolidated domains) under dynamic and quasi-static supercritical CO2 (scCO2)-brine/water flow. In the silica sand sample, the bulk εr (εb) for scCO2-water decreases as the temperature increases. On the contrary, slight increase was seen in the εb with temperature in the carbonate sample for the scCO2-water system. These trends are more conspicuous at high water saturation. The εb-S curves for the scCO2-water flow in the silica sand also show clear dependency on the domain pressure, where εb increases as the domain pressure increases. Furthermore, the bulk σ (σb), at any particular saturation for the scCO2-brine system rises as the temperature increases with more significant increase found at very high water saturation. Both εb and σb values are found to be greater in the limestone than silica sand porous samples for similar porosity values. Based on different injection rates investigated, we do not find significant dynamic effects in the εb-S and σb-S relationships for the scCO2-brine/water system. As such, geoelectrical characteristics can be taken as reliable in the monitoring of two-phase flow system in the porous media. It can be inferred from the results that the geoelectrical techniques are highly dependent on water saturation. This dependence is more conspicuous at higher water saturation. Different mathematical models examined show their reliability at different water saturation ranges. The polynomial fit developed in this work takes into consideration the fluid

  7. Application of a phosphazene derivative as a flame retardant for cotton fabric using conventional method and supercritical CO2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conventional pad-dry-cure (non-scCO2) and supercritical carbon dioxide (scCO2) application methods were investigated to study the effectiveness of a phosphazene derivative as a flame retardant on cotton fabric. 1,1',4,5-tetrahydrotrispiro[1,3,2-diazaphosphole-2,2'-[1,3,5,2,4,6]triazatriphosphinine-4...

  8. Draft Genome Sequences of Supercritical CO2-Tolerant Bacteria Bacillus subterraneus MITOT1 and Bacillus cereus MIT0214

    PubMed Central

    Peet, Kyle C.

    2015-01-01

    We report draft genome sequences of Bacillus subterraneus MITOT1 and Bacillus cereus MIT0214 isolated through enrichment of samples from geologic sequestration sites in pressurized bioreactors containing a supercritical (sc) CO2 headspace. Their genome sequences expand the phylogenetic range of sequenced bacilli and allow characterization of molecular mechanisms of scCO2 tolerance. PMID:25858826

  9. Chemical deposition methods using supercritical fluid solutions

    DOEpatents

    Sievers, Robert E.; Hansen, Brian N.

    1990-01-01

    A method for depositing a film of a desired material on a substrate comprises dissolving at least one reagent in a supercritical fluid comprising at least one solvent. Either the reagent is capable of reacting with or is a precursor of a compound capable of reacting with the solvent to form the desired product, or at least one additional reagent is included in the supercritical solution and is capable of reacting with or is a precursor of a compound capable of reacting with the first reagent or with a compound derived from the first reagent to form the desired material. The supercritical solution is expanded to produce a vapor or aerosol and a chemical reaction is induced in the vapor or aerosol so that a film of the desired material resulting from the chemical reaction is deposited on the substrate surface. In an alternate embodiment, the supercritical solution containing at least one reagent is expanded to produce a vapor or aerosol which is then mixed with a gas containing at least one additional reagent. A chemical reaction is induced in the resulting mixture so that a film of the desired material is deposited.

  10. Exfoliation Propensity of Oxide Scale in Heat Exchangers Used for Supercritical CO2 Power Cycles

    SciTech Connect

    Sabau, Adrian S; Shingledecker, John P.; Kung, Steve; Wright, Ian G.; Nash, Jim

    2016-01-01

    Supercritical CO2 (sCO2) Brayton cycle systems offer the possibility of improved efficiency in future fossil energy power generation plants operating at temperatures of 650 C and above. As there are few data on the oxidation/corrosion behavior of structural alloys in sCO2 at these temperatures, modeling to predict the propensity for oxide exfoliation is not well developed, thus hindering materials selection for these novel cycles. The ultimate goal of this effort is to provide needed data on scale exfoliation behavior in sCO2 for confident alloy selection. To date, a model developed by ORNL and EPRI for the exfoliation of oxide scales formed on boiler tubes in high-temperature, high-pressure steam has proven useful for managing exfoliation in conventional steam plants. A major input provided by the model is the ability to predict the likelihood of scale failure and loss based on understanding of the evolution of the oxide morphologies and the conditions that result in susceptibility to exfoliation. This paper describes initial steps taken to extend the existing model for exfoliation of steam-side oxide scales to sCO2 conditions. The main differences between high-temperature, high-pressure steam and sCO2 that impact the model involve (i) significant geometrical differences in the heat exchangers, ranging from standard pressurized tubes seen typically in steam-producing boilers to designs for sCO2 that employ variously-curved thin walls to create shaped flow paths for extended heat transfer area and small channel cross-sections to promote thermal convection and support pressure loads; (ii) changed operating characteristics with sCO2 due to the differences in physical and thermal properties compared to steam; and (iii) possible modification of the scale morphologies, hence properties that influence exfoliation behavior, due to reaction with carbon species from sCO2. The numerical simulations conducted were based on an assumed sCO2 operating schedule and several

  11. Biological Properties of Fucoxanthin in Oil Recovered from Two Brown Seaweeds Using Supercritical CO2 Extraction

    PubMed Central

    Periaswamy Sivagnanam, Saravana; Yin, Shipeng; Choi, Jae Hyung; Park, Yong Beom; Woo, Hee Chul; Chun, Byung Soo

    2015-01-01

    The bioactive materials in brown seaweeds hold great interest for developing new drugs and healthy foods. The oil content in brown seaweeds (Saccharina japonica and Sargassum horneri) was extracted by using environmentally friendly supercritical CO2 (SC-CO2) with ethanol as a co-solvent in a semi-batch flow extraction process and compared the results with a conventional extraction process using hexane, ethanol, and acetone mixed with methanol (1:1, v/v). The SC-CO2 method was used at a temperature of 45 °C and pressure of 250 bar. The flow rate of CO2 (27 g/min) was constant for the entire extraction period of 2 h. The obtained oil from the brown seaweeds was analyzed to determine their valuable compounds such as fatty acids, phenolic compounds, fucoxanthin and biological properties including antioxidant, antimicrobial, and antihypertension effects. The amounts of fucoxanthin extracted from the SC-CO2 oils of S. japonica and S. horneri were 0.41 ± 0.05 and 0.77 ± 0.07 mg/g, respectively. High antihypertensive activity was detected when using mixed acetone and methanol, whereas the phenolic content and antioxidant property were higher in the oil extracted by SC-CO2. The acetone–methanol mix extracts exhibited better antimicrobial activities than those obtained by other means. Thus, the SC-CO2 extraction process appears to be a good method for obtaining valuable compounds from both brown seaweeds, and showed stronger biological activity than that obtained by the conventional extraction process. PMID:26035021

  12. Biological Properties of Fucoxanthin in Oil Recovered from Two Brown Seaweeds Using Supercritical CO2 Extraction.

    PubMed

    Sivagnanam, Saravana Periaswamy; Yin, Shipeng; Choi, Jae Hyung; Park, Yong Beom; Woo, Hee Chul; Chun, Byung Soo

    2015-06-01

    The bioactive materials in brown seaweeds hold great interest for developing new drugs and healthy foods. The oil content in brown seaweeds (Saccharina japonica and Sargassum horneri) was extracted by using environmentally friendly supercritical CO2 (SC-CO2) with ethanol as a co-solvent in a semi-batch flow extraction process and compared the results with a conventional extraction process using hexane, ethanol, and acetone mixed with methanol (1:1, v/v). The SC-CO2 method was used at a temperature of 45 °C and pressure of 250 bar. The flow rate of CO2 (27 g/min) was constant for the entire extraction period of 2 h. The obtained oil from the brown seaweeds was analyzed to determine their valuable compounds such as fatty acids, phenolic compounds, fucoxanthin and biological properties including antioxidant, antimicrobial, and antihypertension effects. The amounts of fucoxanthin extracted from the SC-CO2 oils of S. japonica and S. horneri were 0.41 ± 0.05 and 0.77 ± 0.07 mg/g, respectively. High antihypertensive activity was detected when using mixed acetone and methanol, whereas the phenolic content and antioxidant property were higher in the oil extracted by SC-CO2. The acetone-methanol mix extracts exhibited better antimicrobial activities than those obtained by other means. Thus, the SC-CO2 extraction process appears to be a good method for obtaining valuable compounds from both brown seaweeds, and showed stronger biological activity than that obtained by the conventional extraction process. PMID:26035021

  13. Frenkel line and solubility maximum in supercritical fluids.

    PubMed

    Yang, C; Brazhkin, V V; Dove, M T; Trachenko, K

    2015-01-01

    A new dynamic line, the Frenkel line, has recently been proposed to separate the supercritical state into rigid-liquid and nonrigid gaslike fluid. The location of the Frenkel line on the phase diagram is unknown for real fluids. Here we map the Frenkel line for three important systems: CO(2), H(2)O, and CH(4). This provides an important demarcation on the phase diagram of these systems, the demarcation that separates two distinct physical states with liquidlike and gaslike properties. We find that the Frenkel line can have a similar trend as the melting line above the critical pressure. Moreover, we discuss the relationship between unexplained solubility maxima and Frenkel line, and we propose that the Frenkel line corresponds to the optimal conditions for solubility. PMID:25679575

  14. [Efficiency of supercritical fluid extraction for the production of non-volatile terpenoids from Taraxaci radix].

    PubMed

    Kristó, T S; Terdy, P P; Simándi, B; Szöke, E; Lemberkovics, E; Kéry, A

    2001-10-01

    Supercritical fluid extraction (SFE) is an extraction technique which exploits the solvent properties of fluids above their critical point. As a result supercritical fluid extraction was used to gain various active substances from plants. The use of SFE to obtain bioactive substances from medicinal plants over the past twenty years has been proved to be a viable alternative for the extraction of natural compounds. Dandelion (Taraxacum officinale Wiggers et Webers, Asteraceae) is one of the best known European medicinal plants, not only as a traditional medicine but perspective raw material for modern phytopharmaceuticals. From the characteristic principles our attention has been directed to triterpenes and phytosterols with anti-inflammatory activity, which were extracted with supercritical carbon dioxide. Designed experiments were carried out to determine the optimal extraction parameters. The products obtained by supercritical fluids extraction were compared to extracts prepared by traditional extraction method (Soxhlet) with n-hexane and ethyl alcohol solvents. The content of triterpenes and sterols was monitored after saponification by thin layer chromatography-densitometry. The products gained by supercritical fluid extraction were different from the traditional ones both in their appearance and composition. Triterpenes and their esters were extracted quantitatively by supercritical fluid extraction using CO2 as solvent and the extraction dynamic for triterpenes and phytosterols was different. Triterpenes had a higher concentration in the SFE product then in the extracts prepared by traditional methods. PMID:11961900

  15. Supercritical fluid extraction and separation of uranium from other actinides.

    PubMed

    Quach, Donna L; Mincher, Bruce J; Wai, Chien M

    2014-06-15

    The feasibility of separating U from nitric acid solutions of mixed actinides using tri-n-butylphosphate (TBP)-modified supercritical fluid carbon dioxide (sc-CO2) was investigated. The actinides U, Np, Pu, and Am were extracted into sc-CO2 modified with TBP from a range of nitric acid concentrations, in the absence of, or in the presence of, a number of traditional reducing and/or complexing agents to demonstrate the separation of these metals from U under sc-CO2 conditions. The separation of U from Pu using sc-CO2 was successful at nitric acid concentrations of less than 3M in the presence of acetohydroxamic acid (AHA) or oxalic acid (OA) to mitigate Pu extraction, and the separation of U from Np was successful at nitric acid concentrations of less than 1M in the presence of AHA, OA, or sodium nitrite to mitigate Np extraction. Americium was not well extracted under any condition studied. PMID:24801893

  16. Forsterite [Mg2SiO4)] carbonation in wet supercritical CO2: an in situ high-pressure X-ray diffraction study.

    PubMed

    Todd Schaef, Herbert; McGrail, Bernard P; Loring, John L; Bowden, Mark E; Arey, Bruce W; Rosso, Kevin M

    2013-01-01

    Mechanisms controlling mineral stabilities in contact with injected supercritical fluids containing water are relatively unknown. In this paper, we discuss carbonation reactions occurring with forsterite (Mg(2)SiO(4)) exposed to variably wet supercritical CO(2) (scCO(2)). Transformation reactions were tracked by in situ high-pressure X-ray diffraction in the presence of scCO(2) containing dissolved water. Under modest pressures (90 bar) and temperatures (50 °C), scCO(2) saturated with water converted >70 wt % forsterite to a hydrated magnesium carbonate, nesquehonite (MgCO(3) · 3H(2)O), and magnesite (MgCO(3)) after 72 h. However, comparable tests with scCO(2) at only partial water saturation showed a faster carbonation rate but significantly less nesquehonite formation and no evidence of the anhydrous form (MgCO(3)). The presence and properties of a thin water film, observed by in situ infrared (IR) spectroscopy and with isotopically labeled oxygen ((18)O), appears to be critical for this silicate mineral to carbonate in low water environments. The carbonation products formed demonstrated by temperature and water-content dependence highlights the importance of these kinds of studies to enable better predictions of the long-term fate of geologically stored CO(2). PMID:22612304

  17. Evaluation of progesterone permeability from supercritical fluid processed dispersion systems.

    PubMed

    Falconer, James R; Wen, Jingyuan; Zargar-Shoshtari, Sara; Chen, John J; Farid, Mohammed; El Maghraby, Gamal M; Alany, Raid G

    2014-03-01

    The aim of this study was to investigate the permeability of unique dispersion systems prepared by supercritical fluid (SCF) processing, to deliver bioidentical progesterone (PGN) across mouse skin. Semisolid dispersions of PGN were made up of either polyethylene glycol (PEG) 400/4000, Gelucire 44/14, d-α-tocopheryl PEG 1000 succinate (TPGS), tanscutol P or myritol 318. SCF dispersion systems were compared with various control formulations; a market cream, aqueous suspension, and three conventionally prepared dispersions – comelted, cosolvent and physically mixed systems. The permeability coefficient in the absence or presence of a permeation enhancer was evaluated using ex vivo mouse skin. The permeation study results for the TPGS/myritol/transcutol P dispersion system prepared using supercritical carbon dioxide (SC-CO2) had a two-fold improvement in transdermal permeation over 24 h compared to the control formulation, 245.7 and 126 µg cm(-2), respectively (p value < 0.05). In this study, the skin integrity and morphology was also investigated for changes due to the formulation constituents using histological examination and Fourier transform infrared spectroscopy. The particles from the gas-saturated suspension method and SC-CO2 together with TPGS/myritol/transcutol P may offer potential advantages over the available cream on the market based on the vastly improved lag time and flux of PGN across the skin. PMID:23432633

  18. TheU-Tube: A Novel System for Acquiring Borehole Fluid Samplesfrom a Deep Geologic CO2 Sequestration Experiment

    SciTech Connect

    Freifeld, Barry M.; Trautz, Robert C.; Kharaka, Yousif K.; Phelps, Tommy J.; Myer, Larry R.; Hovorka, Susan D.; Collins, Daniel J.

    2005-03-17

    A novel system has been deployed to obtain geochemical samples of water and gas, at in situ pressure, during a geologic CO2 sequestration experiment conducted in the Frio brine aquifer in Liberty County, Texas. Project goals required high-frequency recovery of representative and uncontaminated aliquots of a rapidly changing two-phase (supercritical CO2-brine) fluid from 1.5 km depth. The datasets collected, using both the liquid and gas portions of the downhole samples, provide insights into the coupled hydro-geochemical issues affecting CO2 sequestration in brine-filled formations. While the basic premise underlying the U-Tube sampler is not new, the system is unique because careful consideration was given to the processing of the recovered two-phase fluids. In particular, strain gauges mounted beneath the high-pressure surface sample cylinders measured the ratio of recovered brine to supercritical CO2. A quadrupole mass spectrometer provided real-time gas analysis for perfluorocarbon and noble gas tracers that were injected along with the CO2. The U-Tube successfully acquired frequent samples, facilitating accurate delineation of the arrival of the CO2 plume, and on-site analysis revealed rapid changes in geochemical conditions.

  19. Effects of fluid dynamics on cleaning efficacy of supercritical fluids

    SciTech Connect

    Phelps, M.R.; Willcox, W.A.; Silva, L.J.; Butner, R.S.

    1993-03-01

    Pacific Northwest Laboratory (PNL) and Boeing Aerospace Company are developing a process to clean metal parts using a supercritical solvent. This work is part of an effort to address issues inhibiting the rapid commercialization of Supercritical Fluid Parts Cleaning (SFPC). PNL assembled a SFPC test stand to observe the relationship between the fluid dynamics of the system and the mass transfer of a contaminant from the surface of a contaminated metal coupon into the bulk fluid. The bench-scale test stand consists of a Berty'' autoclave modified for these tests and supporting hardware to achieve supercritical fluids parts cleaning. Three separate sets of tests were conducted using supercritical carbon dioxide. For the first two tests, a single stainless steel coupon was cleaned with organic solvents to remove surface residue, doped with a single contaminant, and then cleaned in the SFPC test stand. Contaminants studied were Dow Corning 200 fluid (dimethylpolysiloxane) and Castle/Sybron X-448 High-temperature Oil (a polybutane/mineral oil mixture). A set of 5-minute cleaning runs was conducted for each dopant at various autoclave impeller speeds. Test results from the first two sets of experiments indicate that precision cleaning for difficult-to-remove contaminants can be dramatically improved by introducing and increasing turbulence within the system. Metal coupons that had been previously doped with aircraft oil were used in a third set of tests. The coupons were placed in the SFPC test stand and subjected to different temperatures, pressures, and run times at a constant impeller speed. The cleanliness of each part was measured by Optically Stimulated Electron Emission. The third set of tests show that levels of cleanliness attained with supercritical carbon dioxide compare favorably with solvent and aqueous cleaning levels.

  20. Effects of fluid dynamics on cleaning efficacy of supercritical fluids

    SciTech Connect

    Phelps, M.R.; Willcox, W.A.; Silva, L.J.; Butner, R.S.

    1993-03-01

    Pacific Northwest Laboratory (PNL) and Boeing Aerospace Company are developing a process to clean metal parts using a supercritical solvent. This work is part of an effort to address issues inhibiting the rapid commercialization of Supercritical Fluid Parts Cleaning (SFPC). PNL assembled a SFPC test stand to observe the relationship between the fluid dynamics of the system and the mass transfer of a contaminant from the surface of a contaminated metal coupon into the bulk fluid. The bench-scale test stand consists of a ``Berty`` autoclave modified for these tests and supporting hardware to achieve supercritical fluids parts cleaning. Three separate sets of tests were conducted using supercritical carbon dioxide. For the first two tests, a single stainless steel coupon was cleaned with organic solvents to remove surface residue, doped with a single contaminant, and then cleaned in the SFPC test stand. Contaminants studied were Dow Corning 200 fluid (dimethylpolysiloxane) and Castle/Sybron X-448 High-temperature Oil (a polybutane/mineral oil mixture). A set of 5-minute cleaning runs was conducted for each dopant at various autoclave impeller speeds. Test results from the first two sets of experiments indicate that precision cleaning for difficult-to-remove contaminants can be dramatically improved by introducing and increasing turbulence within the system. Metal coupons that had been previously doped with aircraft oil were used in a third set of tests. The coupons were placed in the SFPC test stand and subjected to different temperatures, pressures, and run times at a constant impeller speed. The cleanliness of each part was measured by Optically Stimulated Electron Emission. The third set of tests show that levels of cleanliness attained with supercritical carbon dioxide compare favorably with solvent and aqueous cleaning levels.

  1. Mixtures of SF6 CO2 as working fluids for geothermal power plants

    SciTech Connect

    Yin, Hebi; Sabau, Adrian S; Conklin, Jim; McFarlane, Joanna; Qualls, A L

    2013-01-01

    In this paper, supercritical/transcritical thermodynamic cycles using mixtures of SF6 CO2 as working fluids were investigated for geothermal power plants. The system of equations that described the thermodynamic cycle was solved using a Newton-Raphson method. This approach allows a high computational efficiency even when thermophysical properties of the working fluid depend strongly on the temperature and pressure. The thermophysical properties of the mixtures were obtained from National Institute of Standards and Technology (NIST) REFPROP software and constituent cubic equations. The local heat transfer coefficients in the heat exchangers were calculated based on the local properties of the working fluid, geothermal brine, and cooling water. The heat exchanger areas required were calculated. Numerical simulation results presented for different cycle configurations were used to assess the effects of the SF6 fraction in CO2, brine temperature, and recuperator size on the cycle thermal efficiency, and size of heat exchangers for the evaporator and condenser. Optimal thermodynamic cycle efficiencies were calculated to be approximately 13 and 15% mole content of SF6 in a CO2- SF6 mixture for a Brayton cycle and a Rankine cycle, respectively.

  2. Transport and relaxation processes in supercritical fluids

    NASA Astrophysics Data System (ADS)

    Jonas, J.

    1985-11-01

    Preparations for the study of naphthalene diffusion dissolved in the supercritical fluids carbon dioxide and ethylene have proceeded as follows. We plan to use the fixed field gradient NMR technique to monitor the diffusion of the dissolved naphthalene. However, the technique is not feasible in systems with spin-spin coupling among the nuclei of interest; unfortunately the protons on naphthalene exhibit this coupling. We thus intend to use totally deuterated naphthalene and monitor the deuterium signal, a nucleus whose coupling is negligible. We therefore have designed and built a new high pressure NMR probe for the measurement of deuterium. This probe is similar to the one used in the previous naphthalene solubility study, and accommodates the same supercritical sample cells. The probe is machined from Vespel SP-1 (a high temperature plastic), and houses a 17-1/2 turn solenoid NMR coil along with thermocouples located slightly above and below the sample area. The probe has been successfully tested to 2 kbar gas pressure. The data acquisition system for the NMR spectrometer used for supercritical fluid studies has been developed and described in this report.

  3. Near-infrared spectroscopic investigation of water in supercritical CO2 and the effect of CaCl2

    SciTech Connect

    Wang, Zheming; Felmy, Andrew R.; Thompson, Christopher J.; Loring, John S.; Joly, Alan G.; Rosso, Kevin M.; Schaef, Herbert T.; Dixon, David A.

    2013-01-01

    Near-infrared (NIR) spectroscopy was applied to investigate the dissolution and chemical interaction of water dissolved into supercritical carbon dioxide (scCO2) and the influence of CaCl2 in the co-existing aqueous phase at fo empe e : 40 50 75 nd 100 C at 90 atm. Consistent with the trend of the vapor pressure of water, the solubility of pure water in scCO2 inc e ed f om 40 °C (0.32 mole%) o 100 °C (1.61 mole%). The presence of CaCl2 negatively affects the solubility of water in scCO2: at a given temperature and pressure the solubility of water decreased as the concentration of CaCl2 in the aqueous phase increased, following the trend of the activity of water. A 40 °C, the water concentration in scCO2 in contact with saturated CaCl2 aqueous solution was only 0.16 mole%, a drop of more than 50% as compared to pure water while that a 100 °C was 1.12 mole%, a drop of over 30% as compared to pure water, under otherwise the same conditions. Analysis of the spectral profiles suggested that water dissolved into scCO2 exists in the monomeric form under the evaluated temperature and pressure conditions, for both neat water and CaCl2 solutions. However, its rotational degrees of freedom decrease at lower temperatures due to higher fluid densities, leading to formation of weak H2O:CO2 Lewis acid-base complexes. Similarly, the nearly invariant spectral profiles of dissolved water in the presence and absence of saturated CaCl2 under the same experimental conditions was taken as evidence that CaCl2 dissolution in scCO2 was limited as the dissolved Ca2+/CaCl2 would likely be highly hydrated and would alter the overall spectra of waters in the scCO2 phase.

  4. Using supercritical fluids to refine hydrocarbons

    DOEpatents

    Yarbro, Stephen Lee

    2014-11-25

    This is a method to reactively refine hydrocarbons, such as heavy oils with API gravities of less than 20.degree. and bitumen-like hydrocarbons with viscosities greater than 1000 cp at standard temperature and pressure using a selected fluid at supercritical conditions. The reaction portion of the method delivers lighter weight, more volatile hydrocarbons to an attached contacting device that operates in mixed subcritical or supercritical modes. This separates the reaction products into portions that are viable for use or sale without further conventional refining and hydro-processing techniques. This method produces valuable products with fewer processing steps, lower costs, increased worker safety due to less processing and handling, allow greater opportunity for new oil field development and subsequent positive economic impact, reduce related carbon dioxide, and wastes typical with conventional refineries.

  5. Supercritical fluids and their applications in biotechnology and related areas.

    PubMed

    Williams, John R; Clifford, Anthony A; al-Saidi, Salim H R

    2002-11-01

    This article serves as an overview, introducing the currently popular area of supercritical fluids (SFs) and their uses in biotechnology and related areas. It covers the fundamentals of supercritical science and moves on to the biotechnological and associated applications of these fluids. Subject areas covered include pure substances as supercritical fluids, the properties of supercritical fluids, organic cosolvents, solubility, and the following applications: extraction, chromatography, reactions, particle production, deposition, and the drying of biological specimens. Within each application, and where possible, the basic principles of the technique are given, as well as a description of the history, instrumentation, methodology, uses, problems encountered, and advantages over the traditional, nonsupercritical methods. PMID:12448881

  6. Bioethanol production from raffinate phase of supercritical CO2 extracted Stevia rebaudiana leaves.

    PubMed

    Coban, Isik; Sargin, Sayit; Celiktas, Melih Soner; Yesil-Celiktas, Ozlem

    2012-09-01

    The extracts of Stevia rebaudiana are marketed as dietary supplements and utilized as natural sweetening agent in food products. Subsequent to extraction on industrial scale, large quantities of solid wastes are produced. The aim of this study was to investigate the bioconversion efficiency of supercritical CO(2) extracted S. rebaudiana residues. Therefore, leaves were extracted with supercritical CO(2) and ethanol mixture in order to obtain glycosides, then the raffinate phase was hydrolyzed by both dilute acid and various concentrations of cellulase and β-glucosidase cocktail. The maximum yield of reducing sugars reached 25.67 g/L under the optimal conditions of enzyme pretreatment, whereas 32.00 g/L was reached by consecutive enzymatic and acid hydrolyses. Bioethanol yield (20 g/L, 2.0% inoculum, 2 days) based on the sugar consumed was 45.55% corresponding to a productivity of 0.19 kg/m(3)h which demonstrates challenges to be utilized as a potential feedstock for the production of bioethanol. PMID:22784953

  7. Photothermal deflection in a supercritical fluid

    NASA Astrophysics Data System (ADS)

    Briggs, Matthew E.; Gammon, Robert W.

    1994-11-01

    The total losses due to absorption and scatter from the best optical coatings can be made as low as supercritical fluid, instead of an ordinary (non-critical) fluid, as the sensing fluid in a collinear photothermal-deflection apparatus. The noise floor in our surface-absorption measurements using supercritical xenon, Tc equals 16.7 degree(s)C, corresponds to an absorptance A equals Pabsorbed/Pincident equals 10-10 under illumination of 1 W. Bulk absorption measurements are similarly enhanced: the noise floor corresponds to an absorption coefficient of (alpha) equals 10-13 cm-1 for 1 W of illumination in a sample of length 1 cm. These levels are three orders of magnitude more sensitive than any previously reported. The enhancement is brought about by the divergence in the coefficient of thermal expansion of a fluid near the critical point. In attempting to use this sensitivity to measure the absorption in transmission of low-absorbing (

  8. Supercritical fluids: Reactions, materials and applications

    SciTech Connect

    Tumas, W.; Jacobson, G.B.; Josephsohn, N.S.; Brown, G.H.

    1999-04-09

    A number of important processes utilizing supercritical fluids have been either implemented or are emerging for extractions, separations and a wide range of cleaning applications. Supercritical fluids can be reasonable solvents yet share many of the advantages of gases including miscibility with other gases (i.e. hydrogen and oxygen), low viscosities and high diffusivities. Carbon dioxide has the further advantages of being nontoxic, nonflammable, inexpensive and currently unregulated. The use of compressed gases, either as liquids or supercritical fluids, as reaction media offers the opportunity to replace conventional hazardous solvents and also to optimize and potentially control the effect of solvent on chemical and material processing. The last several years has seen a significant growth in advances in chemical synthesis, catalytic transformations and materials synthesis and processing. The authors report on results from an exploratory program at Los Alamos National Laboratory aimed at investigating the use of dense phase fluids, particularly carbon dioxide, as reaction media for homogeneous, heterogeneous and phase-separable catalytic reactions in an effort to develop new, environmentally-friendly methods for chemical synthesis and processing. This approach offers the possibility of opening up substantially different chemical pathways, increasing selectivity at higher reaction rates, facilitating downstream separations and mitigating the need for hazardous solvents. Developing and understanding chemical and catalytic transformations in carbon dioxide could lead to greener chemistry at three levels: (1) Solvent replacement; (2) Better chemistry (e.g. higher reactivity, selectivity, less energy consumption); and (3) New chemistry (e.g. novel separations, use of COP{sub 2} as a C-1 source).

  9. Supercritical fluid extraction of N-nitrosamines

    SciTech Connect

    Tewani, S.

    1993-01-01

    The detailed chemistry of N-nitrosamines including the mechanism of carcinogenicity, modes of formation, inhibition and destruction are discussed in detail. The occurrence and risk assessment of human exposure of these suspect cancer agents is described. The methods of isolation and analysis of N-nitrosamines are critically discussed with emphasis on Gas Chromatography (GC)-Electrochemical Detectors, GC-High Resolution Mass Spectrometry (GC-HRMS), GC-Thermal Energy Analyser (GC-TEA). The theoretical concepts of supercritical fluid extraction (SFE) are discussed. A comparison of physical and chemical properties of supercritical fluids (SF) with other phases is given. A comparison of static, dynamic, recirculating SFEs shows the versatility of this technique. The advantages over conventional methods such as Soxhlet extraction are discussed. The instrumentation and operational technique of a laboratory built supercritical fluid extractor is explained. A brief review of applications (industrial and analytical) of SFE is given. The evaluation of SFE for analytical sample preparation and analyses of volatile N-nitrosamines (VNAs), tobacco specific N-nitrosamines (TSNAs), and N-nitrosodiethanolamine (NDELA) from spiked matrices, tobacco and cutting fluids is presented. Experimental parameters such as pressure, temperature, equilibration time, collector materials, modifier are evaluated to optimize the recoveries. The extracts are analysed by GC-TEA which is already proven to be highly selective and sensitive to quantitation of N-nitrosamines. The extraction of VNAs in pure SF-CO[sub 2] is quantitative at moderate pressures and low temperatures. For the extraction of TSNAs and NDELA, it is imperative to have high pressures and presence of an additive ([approximately]10% methanol) to achieve satisfactory results. This study offers a simple, rapid, accurate and environmentally advantageous sample preparation technique for the estimation of N-nitrosamines at nanogram levels.

  10. Injection of Super-Critical CO2 in Brine Saturated Sandstone:

    NASA Astrophysics Data System (ADS)

    Ott, Holger; de Kloe, Kees; Taberner, Conxita; Marcelis, Fons; Makurat, Axel

    2010-05-01

    Presently, large-scale geological sequestration of CO2, originating from sources like fossil-fueled power plants and contaminated gas production, is seen as an option to reduce anthropogenic emission of greenhouse gases to the atmosphere. Deep saline aquifers and depleted oil and gas fields are potential subsurface deposits for CO2. Injected CO2, however, interacts physically and chemically with the formation leading to uncertainties for CCS projects. One of these uncertainties is related to a dry-out zone that is likely to form around the well bore owing to the injection of dry CO2. Precipitation of salt (mainly halite) that is associated with that drying out of a saline formation has the potential to impair injectivity, and could even lead to the loss of a well. If dry (or under-saturated), super-critical (SC) CO2 is injected into water-bearing geological formations like saline aquifers, water is removed by either advection of the aqueous phase or by evaporation of water and subsequent advection in the injected CO2-rich phase. Both mechanisms act in parallel, however while advection of the aqueous phase decreases with increasing CO2 saturation (diminished mobility), evaporation becomes increasingly important as the aqueous phase becomes immobile. Below residual water saturation, only evaporation takes place and the formation dries out if no additional source of water is available. If water evaporates, the salts originally present in the water are left behind. In case of highly saline formations, the amount of salt that potentially precipitates per unit volume can be quite substantial. It depends on salinity, the solubility limit of water in the CO2 rich phase, and on the ratio of advection and evaporation rates. Since saturations and flow rates cover a large range as functions of space and time close to the well bore, there is no easy answer to the questions whether, where and how salt precipitation impacts injectivity. The present paper presents results of core

  11. Occurrence of turbulent flow conditions in supercritical fluid chromatography.

    PubMed

    De Pauw, Ruben; Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

    2014-09-26

    Having similar densities as liquids but with viscosities up to 20 times lower (higher diffusion coefficients), supercritical CO2 is the ideal (co-)solvent for fast and/or highly efficient separations without mass-transfer limitations or excessive column pressure drops. Whereas in liquid chromatography the flow remains laminar in both the packed bed and tubing, except in extreme cases (e.g. in a 75 μm tubing, pure acetonitrile at 5 ml/min), a supercritical fluid can experience a transition from laminar to turbulent flow in more typical operation modes. Due to the significant lower viscosity, this transition for example already occurs at 1.3 ml/min for neat CO2 when using connection tubing with an ID of 127 μm. By calculating the Darcy friction factor, which can be plotted versus the Reynolds number in a so-called Moody chart, typically used in fluid dynamics, higher values are found for stainless steel than PEEK tubing, in agreement with their expected higher surface roughness. As a result turbulent effects are more pronounced when using stainless steel tubing. The higher than expected extra-column pressure drop limits the kinetic performance of supercritical fluid chromatography and complicates the optimization of tubing ID, which is based on a trade-off between extra-column band broadening and pressure drop. One of the most important practical consequences is the non-linear increase in extra-column pressure drop over the tubing downstream of the column which leads to an unexpected increase in average column pressure and mobile phase density, and thus decrease in retention. For close eluting components with a significantly different dependence of retention on density, the selectivity can significantly be affected by this increase in average pressure. In addition, the occurrence of turbulent flow is also observed in the detector cell and connection tubing. This results in a noise-increase by a factor of four when going from laminar to turbulent flow (e.g. going

  12. Experimental methods for the simulation of supercritical CO2 injection at laboratory scale aimed to investigate capillary trapping

    NASA Astrophysics Data System (ADS)

    Trevisan, L.; Illangasekare, T. H.; Rodriguez, D.; Sakaki, T.; Cihan, A.; Birkholzer, J. T.; Zhou, Q.

    2011-12-01

    Geological storage of carbon dioxide in deep geologic formations is being considered as a technical option to reduce greenhouse gas loading to the atmosphere. The processes associated with the movement and stable trapping are complex in deep naturally heterogeneous formations. Three primary mechanisms contribute to trapping; capillary entrapment due to immobilization of the supercritical fluid CO2 within soil pores, liquid CO2 dissolving in the formation water and mineralization. Natural heterogeneity in the formation is expected to affect all three mechanisms. A research project is in progress with the primary goal to improve our understanding of capillary and dissolution trapping during injection and post-injection process, focusing on formation heterogeneity. It is expected that this improved knowledge will help to develop site characterization methods targeting on obtaining the most critical parameters that capture the heterogeneity to design strategies and schemes to maximize trapping. This research combines experiments at the laboratory scale with multiphase modeling to upscale relevant trapping processes to the field scale. This paper presents the results from a set of experiments that were conducted in an intermediate scale test tanks. Intermediate scale testing provides an attractive alternative to investigate these processes under controlled conditions in the laboratory. Conducting these types of experiments is highly challenging as methods have to be developed to extrapolate the data from experiments that are conducted under ambient laboratory conditions to high temperatures and pressures settings in deep geologic formations. We explored the use of a combination of surrogate fluids that have similar density, viscosity contrasts and analogous solubility and interfacial tension as supercritical CO2-brine in deep formations. The extrapolation approach involves the use of dimensionless numbers such as Capillary number (Ca) and the Bond number (Bo). A set of

  13. Micro-PIV Study of Supercritical CO2-Water Interactions in Porous Micromodels

    NASA Astrophysics Data System (ADS)

    Kazemifar, Farzan; Blois, Gianluca; Christensen, Kenneth T.

    2015-11-01

    Multiphase flow of immiscible fluids in porous media is encountered in numerous natural systems and engineering applications such as enhanced oil recovery (EOR), and CO2 sequestration among others. Geological sequestration of CO2 in saline aquifers has emerged as a viable option for reducing CO2 emissions, and thus it has been the subject of numerous studies in recent years. A key objective is improving the accuracy of numerical models used for field-scale simulations by incorporation/better representation of the pore-scale flow physics. This necessitates experimental data for developing, testing and validating such models. We have studied drainage and imbibition processes in a homogeneous, two-dimensional porous micromodel with CO2 and water at reservoir-relevant conditions. Microscopic particle image velocimetry (micro-PIV) technique was applied to obtain spatially- and temporally-resolved velocity vector fields in the aqueous phase. The results provide new insight into the flow processes at the pore scale.

  14. Modeling and optimization of a concentrated solar supercritical CO2 power plant

    NASA Astrophysics Data System (ADS)

    Osorio, Julian D.

    Renewable energy sources are fundamental alternatives to supply the rising energy demand in the world and to reduce or replace fossil fuel technologies. In order to make renewable-based technologies suitable for commercial and industrial applications, two main challenges need to be solved: the design and manufacture of highly efficient devices and reliable systems to operate under intermittent energy supply conditions. In particular, power generation technologies based on solar energy are one of the most promising alternatives to supply the world energy demand and reduce the dependence on fossil fuel technologies. In this dissertation, the dynamic behavior of a Concentrated Solar Power (CSP) supercritical CO2 cycle is studied under different seasonal conditions. The system analyzed is composed of a central receiver, hot and cold thermal energy storage units, a heat exchanger, a recuperator, and multi-stage compression-expansion subsystems with intercoolers and reheaters between compressors and turbines respectively. The effects of operating and design parameters on the system performance are analyzed. Some of these parameters are the mass flow rate, intermediate pressures, number of compression-expansion stages, heat exchangers' effectiveness, multi-tank thermal energy storage, overall heat transfer coefficient between the solar receiver and the environment and the effective area of the recuperator. Energy and exergy models for each component of the system are developed to optimize operating parameters in order to lead to maximum efficiency. From the exergy analysis, the components with high contribution to exergy destruction were identified. These components, which represent an important potential of improvement, are the recuperator, the hot thermal energy storage tank and the solar receiver. Two complementary alternatives to improve the efficiency of concentrated solar thermal systems are proposed in this dissertation: the optimization of the system's operating

  15. Mass transfer in supercritical fluids instancing selected fluids in supercritical carbon dioxide

    NASA Astrophysics Data System (ADS)

    Hu, Miao; Benning, Rainer; Delgado, Antonio; Ertunc, Oezguer

    solvent -sub-critical CO2. The ex-periment pressure is reached by reducing the volume of the container above the critical pressure of the solvent. For nucleation the container is firstly filled with saturated mixture of solvent -supercritical CO2 and the sample, the experiment pressure is achieved by enlarging the volume of the container below the critical pressure of the solvent. During the experiments the pressure and temperature data are monitored and recorded. As a direct observation means a high speed camera is used, the visual changes inside are recorded through the windows integrated on the container. The experiments are carried out under three different initial conditions, namely with three start temperatures (313K, 333K and 353K), to cover the area from vicinity of the critical point. This research serves as a pilot project topic in cooperation with DLR, which has the ultimate aim of performing the experiments of mass transfer processes in a longtime microgravity facility (e.g. ISS) in order to further explore the influences and utilities of earth gravity on these basic transport processes.

  16. Modern supercritical fluid technology for food applications.

    PubMed

    King, Jerry W

    2014-01-01

    This review provides an update on the use of supercritical fluid (SCF) technology as applied to food-based materials. It advocates the use of the solubility parameter theory (SPT) for rationalizing the results obtained when employing sub- and supercritical media to food and nutrient-bearing materials and for optimizing processing conditions. Total extraction and fractionation of foodstuffs employing SCFs are compared and are illustrated by using multiple fluids and unit processes to obtain the desired food product. Some of the additional prophylactic benefits of using carbon dioxide as the processing fluid are explained and illustrated with multiple examples of commercial products produced using SCF media. I emphasize the role of SCF technology in the context of environmentally benign and sustainable processing, as well as its integration into an overall biorefinery concept. Conclusions are drawn in terms of current trends in the field and future research that is needed to secure new applications of the SCF platform as applied in food science and technology. PMID:24328430

  17. Effects of supercritical carbon dioxide (SC-CO(2)) oil extraction on the cell wall composition of almond fruits.

    PubMed

    Femenia, A; García-Marín, M; Simal, S; Rosselló, C; Blasco, M

    2001-12-01

    Extraction of oil from almond fruits using supercritical carbon dioxide (SC-CO(2)) was carried out at 50 degrees C and 330 bar on three sets of almonds: raw almond seeds, raw almond kernels, and toasted almond seeds. Three different oil extraction percentages were applied on each set ranging from approximately 15 to 16%, from approximately 27 to 33%, and from approximately 49 to 64%. Although no major changes were detected in the fatty acid composition between fresh and partially defatted samples, carbohydrate analysis of partially defatted materials revealed important changes in cell wall polysaccharides from almond tissues. Thus, at low extraction percentages (up to approximately 33%), pectic polysaccharides and hemicellulosic xyloglucans were the main type of polymers affected, suggesting the modification of the cell wall matrix, although without breakage of the walls. Then, as supercritical fluid extraction (SCFE) continues and higher extraction rates are achieved (up to approximately 64%), a major disruption of the cell wall occurred as indicated by the losses of all major types of cell wall polysaccharides, including cellulose. These results suggest that, under the conditions used for oil extraction using SC-CO(2), fatty acid chains are able to exit the cells through nonbroken walls; the modification of the pectin-hemicellulose network might have increased the porosity of the wall. However, as high pressure is being applied, there is a progressive breakage of the cell walls allowing the free transfer of the fatty acid chains from inside the cells. These findings might contribute to providing the basis for the optimization of SCFE procedures based on plant food sources. PMID:11743770

  18. Modeling and optimization of a concentrated solar supercritical CO2 power plant

    NASA Astrophysics Data System (ADS)

    Osorio, Julian D.

    Renewable energy sources are fundamental alternatives to supply the rising energy demand in the world and to reduce or replace fossil fuel technologies. In order to make renewable-based technologies suitable for commercial and industrial applications, two main challenges need to be solved: the design and manufacture of highly efficient devices and reliable systems to operate under intermittent energy supply conditions. In particular, power generation technologies based on solar energy are one of the most promising alternatives to supply the world energy demand and reduce the dependence on fossil fuel technologies. In this dissertation, the dynamic behavior of a Concentrated Solar Power (CSP) supercritical CO2 cycle is studied under different seasonal conditions. The system analyzed is composed of a central receiver, hot and cold thermal energy storage units, a heat exchanger, a recuperator, and multi-stage compression-expansion subsystems with intercoolers and reheaters between compressors and turbines respectively. The effects of operating and design parameters on the system performance are analyzed. Some of these parameters are the mass flow rate, intermediate pressures, number of compression-expansion stages, heat exchangers' effectiveness, multi-tank thermal energy storage, overall heat transfer coefficient between the solar receiver and the environment and the effective area of the recuperator. Energy and exergy models for each component of the system are developed to optimize operating parameters in order to lead to maximum efficiency. From the exergy analysis, the components with high contribution to exergy destruction were identified. These components, which represent an important potential of improvement, are the recuperator, the hot thermal energy storage tank and the solar receiver. Two complementary alternatives to improve the efficiency of concentrated solar thermal systems are proposed in this dissertation: the optimization of the system's operating

  19. Solute partial molal volumes in supercritical fluids

    SciTech Connect

    Eckert, C.A.; Ziger, D.H.; Johnston, K.P.; Kim, S.

    1986-06-05

    A novel technique is described for the measurement of the partial molal volume at infinite dilution of solutes in supercritical fluids. Results are reported for five systems from 2/sup 0/C above the solvent critical temperature up to 15/sup 0/C above, at pressures from just above the critical pressure to 350 bars. The solute partial molal volumes are small and positive at high pressures, but very large and negative in the highly compressible near-critical region. The results are interpreted in terms of solvent structure and intermolecular forces.

  20. Leaching of organic acids from macromolecular organic matter by non-supercritical CO2

    NASA Astrophysics Data System (ADS)

    Sauer, P.; Glombitza, C.; Kallmeyer, J.

    2012-04-01

    The storage of CO2 in underground reservoirs is discussed controversly in the scientific literature. The worldwide search for suitable storage formations also considers coal-bearing strata. CO2 is already injected into seams for enhanced recovery of coal bed methane. However, the effects of increased CO2 concentration, especially on organic matter rich formations, are rarely investigated. The injected CO2 will dissolve in the pore water, causing a decrease in pH and resulting in acidic formation waters. Huge amounts of low molecular weight organic acids (LMWOAs) are chemically bound to the macromolecular matrix of sedimentary organic matter and may be liberated by hydrolysis, which is enhanced by the acidic porewater. Recent investigations outlined the importance of LMWOAs as a feedstock for microbial life in the subsurface [1]. Therefore, injection of CO2 into coal formations may result in enhanced nutrient supply for subsurface microbes. To investigate the effect of high concentrations of dissolved CO2 on the release of LMWOAs from coal we developed an inexpensive high-pressure high temperature system that allows manipulating the partial pressure of dissolved gases at pressures and temperatures up to 60 MPa and 120° C, respectively. In a reservoir vessel, gases are added to saturate the extraction medium to the desired level. Inside the extraction vessel hangs a flexible and inert PVDF sleeve (polyvinylidene fluoride, almost impermeable for gases), holding the sample and separating it from the pressure fluid. The flexibility of the sleeve allows for subsampling without loss of pressure. Coal samples from the DEBITS-1 well, Waikato Basin, NZ (R0 = 0.29, TOC = 30%). were extracted at 90° C and 5 MPa, either with pure or CO2-saturated water. Subsamples were taken at different time points during the extraction. The extracted LMWOAs such as formate, acetate and oxalate were analysed by ion chromatography. Yields of LMWOAs were higher with pure water than with CO2

  1. Research on Flow Characteristics of Supercritical CO2 Axial Compressor Blades by CFD Analysis

    NASA Astrophysics Data System (ADS)

    Takagi, Kazuhisa; Muto, Yasushi; Ishizuka, Takao; Kikura, Hiroshige; Aritomi, Masanori

    A supercritical CO2 gas turbine of 20MPa is suitable to couple with the Na-cooled fast reactor since Na - CO2 reaction is mild at the outlet temperature of 800K, the cycle thermal efficiency is relatively high and the size of CO2 gas turbine is very compact. In this gas turbine cycle, a compressor operates near the critical point. The property of CO2 and then the behavior of compressible flow near the critical point changes very sharply. So far, such a behavior is not examined sufficiently. Then, it is important to clarify compressible flow near the critical point. In this paper, an aerodynamic design of the axial supercritical CO2 compressor for this system has been carried out based on the existing aerodynamic design method of Cohen1). The cycle design point was selected to achieve the maximum cycle thermal efficiency of 43.8%. For this point, the compressor design conditions were determined. They are a mass flow rate of 2035kg/s, an inlet temperature of 308K, an inlet static pressure of 8.26MPa, an outlet static pressure of 20.6MPa and a rotational speed of 3600rpm. The mean radius was constant through axial direction. The design point was determined so as to keep the diffusion factor and blade stress within the allowable limits. Number of stages and an expected adiabatic efficiency was 14 and 87%, respectively. CFD analyses by FLUENT have been done for this compressor blade. The blade model consists of one set of a guide vane, a rotor blade and a stator blade. The analyses were conducted under the assumption both of the real gas properties and also of the modified ideal gas properties. Using the real gas properties, analysis was conducted for the 14th blade, whose condition is remote from the critical point and the possibility of divergence is very small. Then, the analyses were conducted for the blade whose conditions are nearer to the critical point. Gradually, divergence of calculation was encountered. Convergence was relatively easy for the modified ideal

  2. Modeling Study on Injection of Supercritical CO2 Into a Deep Saline Carbonate Formation

    NASA Astrophysics Data System (ADS)

    Zhang, G.; Taberner, C.; Xu, T.; Cartwright, L.

    2008-12-01

    A modeling study on injection of supercritical CO2 into a deep saline carbonate formation was performed using TOUGHREACT Pitzer ion-interaction model. The carbonate formation consists of calcite (72.5%), dolomite (21.5%) and anhydrite (<6%). The brine of the formation is known as NaCl-dominant with salinity at about 250,000 ppm (NaCl equivalent), temperature at 102° C and pressure at 225 bars. The detailed chemical composition of the brine was unknown. It was reconstructed according to the salinity and the known detailed composition of a brine from a similar formation with slightly lower salinity (about 190,000 ppm). The reconstructed formation brine has an ionic strength ~5 molal and pH 5.4 with considerable concentrations of Ca+2, Mg+2, HCO3- and SO4-2. CO2 injection was considered at a constant rate and for a period of 1 year, through a vertical well in a 2D radial model domain, and a horizontal well in a 3D model domain, respectively. The preliminary simulations found that: (1) at the end of the injection, a dryout zone is developed within a few meters from the injection well due to displacement by the injected supercritical CO2 and the evaporation of water from brine into CO2; (2) at the front of the dryout zone, brine is further concentrated (ionic strength up 20 molal) due to water evaporation, pH is lowered to 3.1, halite (NaCl) and anhydrite (CaSO4) precipitate, and the brine is converted into CaCl2-dominant; (3) precipitation of halite in the dryout zone reduces the formation porosity by about 5%-10%; (4) HCl gas is generated from the dryout front; (5) calcite dissolves close to the injection well and precipitates at areas far from the well, however, the overall mineral trapping is not significant in hundreds of years for this carbonate formation. These findings are valuable for the assessment of the potentials of this carbonate formation for CO2 sequestration, injectivity changes, and well degradation by potential corrosion.

  3. Chemical composition and antioxidant properties of candlenut oil extracted by supercritical CO2.

    PubMed

    Siddique, Bazlul Mobin; Ahmad, Anees; Alkarkhi, Abbas F M; Ibrahim, Mahamad Hakimi; K, Mohd Omar A

    2011-05-01

    Candlenut oil was extracted using supercritical CO(2) (SC-CO(2)) with an optimization of parameters, by the response surface methodology. The ground candlenut samples were treated in 2 different ways, that is, dried in either a heat oven (sample moisture content of 2.91%) or dried in a vacuum oven (sample moisture content of 1.98%), before extraction. An untreated sample (moisture content of 4.87%) was used as a control. The maximum percentage of oil was extracted from the heat-oven-dried sample (77.27%), followed by the vacuum-oven-dried sample (74.32%), and the untreated sample (70.12%). At an SC-CO(2) pressure of 48.26 Mpa and 60 min of extraction time, the optimal temperatures for extraction were found to be 76.4 °C, 73.9 °C, and 70.6 °C for the untreated, heat-oven-dried, and vacuum-oven-dried samples, respectively. The heat-oven-dried sample contains the highest percentage of linoleic acid, followed by the untreated and vacuum-oven-dried samples. The antiradical activity of candlenut oil corresponded to an IC(50) value of 30.37 mg/mL. PMID:22417332

  4. Density functional simulations as a tool to probe molecular interactions in wet supercritical CO2

    SciTech Connect

    Glezakou, Vassiliki Alexandra; McGrail, B. Peter

    2013-06-03

    Recent advances in mixed Gaussian and plane wave algorithms have made possible the effective use of density functional theory (DFT) in ab initio molecular dynamics (AIMD) simulations for large and chemically complex models of condensed phase materials. In this chapter, we are reviewing recent progress on the modeling and characterization of co-sequestration processes and reactivity in wet supercritical CO2 (sc-CO2). We examine the molecular transformations of mineral and metal components of a sequestration system in contact with water-bearing scCO2 media and aim to establish a reliable correspondence between experimental observations and theory models with predictive ability and transferability of results in large scale geomechanical simulators. This work is funded by the Department of Energy, Office of Fossil Energy. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research located at Pacific Northwest National Laboratory. The Pacific Norhtwest National Laboratory (PNNL) is operated by Battelle for DOE under contract DE-AC06-76RL01830.

  5. Supercritical CO2 extraction of oilseeds: review of kinetic and equilibrium models.

    PubMed

    del Valle, José M; de la Fuente, Juan C

    2006-01-01

    Mass transfer models on supercritical carbon dioxide (SC-CO2) extraction of vegetable oils are reviewed, that may facilitate the scale-up of laboratory data for industrial design purposes. Reviewed mechanisms of oil transport within the solid matrix include the desorption from the solid, the formation of a shrinking core of condensed oil in a non-adsorbing porous matrix, and diffusion in a homogenous medium. Analyzed simplificat ions of a general mass transfer model include external control of mass transfer rates, internal control of mass transfer rates, consideration of a linear driving force, and steady state approximations, among others. More complex two-stage models, and critical comparisons of some of the proposed models are also included. Trends for the external mass transfer coefficient and effective diffusivity in the solid matrix from studies on SC-CO2 extraction of oil from vegetable substrates are thoroughly discussed and contrasted with those obtained using simpler model systems. The possible effect of the axial dispersion on the rate of extraction is also discussed. Finally, the high-pressure vegetable oil-CO2 phase equilibrium is discussed in connection with its influence on the mass transfer process. Special emphasis is given to the role of the solid matrix on high-pressure phase equilibrium. PMID:16431407

  6. Geochemical modeling of fluid-fluid and fluid-mineral interactions during geological CO2 storage

    NASA Astrophysics Data System (ADS)

    Zhu, C.; Ji, X.; Lu, P.

    2013-12-01

    The long time required for effective CO2 storage makes geochemical modeling an indispensable tool for CCUS. One area of geochemical modeling research that is in urgent need is impurities in CO2 streams. Permitting impurities, such as H2S, in CO2 streams can lead to potential capital and energy savings. However, predicting the consequences of co-injection of CO2 and impurities into geological formations requires the understanding of the phase equilibrium and fluid-fluid interactions. To meet this need, we developed a statistical associating fluid theory (SAFT)-based equation of state (EOS) for the H2S-CO2-H2O-NaCl system at 373.15 CO2 streams may lead to two-phase flow in pipelines. For H2S-CO2 mixtures at a given temperature the bubble and dew pressures decrease with increasing H2S content, while the mass density increases at low pressures and decreases at high pressures. Furthermore, the EoS can be incorporated into reservoir simulators so that the dynamic development of mixed fluid plumes in the reservoir can be simulated. Accurate modeling of fluid-mineral interactions must confront unresolved uncertainties of silicate dissolution - precipitation reaction kinetics. Most prominent among these uncertainties is the well-known lab-field apparent discrepancy in dissolution rates. Although reactive transport models that simulate the interactions between reservoir rocks and brine, and their attendant effects on porosity and permeability changes, have proliferated, whether these results have acceptable uncertainties are unknown. We have conducted a series of batch experiments at elevated temperatures and numerical simulations of coupled dissolution and precipitation reactions. The results show that taking into account

  7. Supercritical Fluid Extraction and Separation of Uranium from Other Actinides

    SciTech Connect

    Donna L. Quach; Bruce J. Mincher; Chien M. Wai

    2014-06-01

    This paper investigates the feasibility of separating uranium from other actinides by using supercritical fluid carbon dioxide (sc-CO2) as a solvent modified with tri-n-butylphosphate (TBP) for the development of an extraction and counter current stripping technique, which would be a more efficient and environmentally benign technology for used nuclear fuel reprocessing compared to traditional solvent extraction. Several actinides (U(VI), Np(VI), Pu(IV), and Am(III)) were extracted in sc-CO2 modified with TBP over a range of nitric acid concentrations and then the actinides were exposed to reducing and complexing agents to suppress their extractability. According to this study, the separation of uranium from plutonium in sc-CO2 modified with TBP was successful at nitric acid concentrations of less than 3 M in the presence of acetohydroxamic acid or oxalic acid, and the separation of uranium from neptunium was successful at nitric acid concentrations of less than 1 M in the presence of acetohydroxamic acid, oxalic acid, or sodium nitrite.

  8. Supercritical fluid extraction of 5-hydroxymethyl-2-furaldehyde from raisins.

    PubMed

    Palma, M; Taylor, L T

    2001-02-01

    An extraction method based on supercritical CO(2) has been developed for the analysis of 5-hydroxymethyl-2-furaldehyde in raisins. To optimize extraction variables, a fractional factorial experimental design was applied. Six extraction variables were optimized. The organic modifier used for increasing the extraction fluid solvating power was the most important factor. Methanol as organic modifier produced 10-fold higher recoveries of 5-hydroxymethyl-2-furaldehyde than ethyl acetate. The efficiency of the organic modifier in the static extraction phase was compared with using it in the dynamic extraction phase. Repeatability of the analysis method was evaluated, which resulted in an RSD of <5%. 5-Hydroxymethyl-2-furaldehyde was quantified in raisins, and the concentration was found to be 0.128 mg/g of raisin. PMID:11262003

  9. Sequential fractionation of grape seeds into oils, polyphenols, and procyanidins via a single system employing CO2-based fluids.

    PubMed

    Ashraf-Khorassani, Mehdi; Taylor, Larry Thomas

    2004-05-01

    Pure supercritical CO(2) was used to remove >95% of the oil from the grape seeds. Subcritical CO(2) modified with methanol was used for the extraction of monomeric polyphenols, whereas pure methanol was used for the extraction of polyphenolic dimers/trimers and procyanidins from grape seed. At optimum conditions, 40% methanol-modified CO(2) removed >79% of catechin and epicatechin from the grape seed. This extract was light yellow in color, and no higher molecular weight procyanidins were detected. Extraction of the same sample after removal of the oils and polyphenols, but now under enhanced solvent extraction conditions using methanol as a solvent, provided a dark red solution shown via electrospray ionization HPLC-MS to contain a relatively high concentration of procyanidins. The uniqueness of the study is attested to by the use of CO(2)-based fluids and the employment of a single instrumental extraction system. PMID:15113138

  10. Experimental study of the hydrogeochemical properties of the Hontomin cap rock under CO2 supercritical conditions

    NASA Astrophysics Data System (ADS)

    Cama, Jordi; Soler, Josep M.; Davila, Gabriela; Luquot, Linda

    2013-04-01

    Gabriela Dávila, Linda Luquot, Jordi Cama and Josep M. Soler Departament de Geociències, Institut de Diagnosi Ambiental i Estudis de l'Aigua (IDAEA), CSIC, Barcelona 08034. The main cap rock for CO2 injection at the PDT Hontomin site (Spain) is a marly shale made up of calcite (56 %), quartz (21%), illite (17%) clinochlore (3%) and others (albite, gypsum, anhydrite, pyrite) (~3%). Contact with CO2-rich acid brines may induce the dissolution of these minerals. Since the brine contains sulfate, gypsum (or anhydrite at depth) may precipitate, which may coat the surface of the dissolving calcite grains and cause their passivation. These mineral reactions will also induce changes in porosity and permeability. Percolation laboratory experiments with Hontomin shale rock cores under controlled pCO2 (8 MPa) are being performed to quantify these processes. In mechanically fractured cores (7.5 mm in diameter and 18 mm in length), two synthetic brines (a sulfate-free solution and a version of the Hontomin formation brine (sulfate solution)) were injected into the rock at constant flow rates (0.2, 1 and 60 mL/h) under CO2 supercritical conditions (pCO2 = 8 MPa and T = 60 °C). As the pH of the injecting brines in equilibrium with a pCO2 of 8 MPa is acidic (~3), it was observed that in the case of the sulfate-free brine experiments, the main processes that yield variation in the hydrodynamic behavior of the fractured rock was the dissolution of calcite, Si-bearing minerals, clinochlore and pyrite. In the sulfate-rich brine experiments, the dissolution of calcite and Si-bearing minerals also occurred, together with gypsum precipitation in the experiments run at low flow rates. As a result, initial fracture permeability tends (i) to stabilize or increase when the cap rock interacts with the sulfate-free brine and (ii) to decrease as the rock interacts with the sulfate-rich brine. The interpretation (reactive transport modeling) of the changes in mineralogy and solution

  11. Ion mobility spectrometry after supercritical fluid chromatography

    SciTech Connect

    Morrissey, M.A.

    1988-01-01

    In this work, a Fourier transform ion mobility spectrometer (FT-IMS) was constructed and evaluated as a detector for supercritical fluid chromatography (SFC). The FT-IMS provides both quantitative and qualitative data of a wide range of compounds, selective and nonselective modes of chromatographic detection, and it is compatible with a wide range of SFC mobile phases. Drift spectra are presented for a number of samples, including polymers, lipids, herbicides, antibiotics, and pharmaceuticals. The unique properties of supercritical fluids made it possible to introduce these compounds into the spectrometer. While the drift spectra presented are generally simple, showing only a quasi-molecular ion, a few are surprising complex. Examples of selective and non-selective detection demonstrate the usefulness of the detector. Examples are presented for fish oil concentrate, bacon grease extract, soil extract, and polymer mixtures. In the case of Triton X-100, a non-ionic surfactant, the FT-IMS was able to selectively detect individual oligomers in the polymer mixture. In the case of a polydimethylsilicone mixture the detector isolated a contaminant in the mixture.

  12. Bio-oil production from biomass via supercritical fluid extraction

    NASA Astrophysics Data System (ADS)

    Durak, Halil

    2016-04-01

    Supercritical fluid extraction is used for producing bio-fuel from biomass. Supercritical fluid extraction process under supercritical conditions is the thermally disruption process of the lignocellulose or other organic materials at 250-400 °C temperature range under high pressure (4-5 MPa). Supercritical fluid extraction trials were performed in a cylindrical reactor (75 mL) in organic solvents (acetone, ethanol) under supercritical conditions with (calcium hydroxide, sodium carbonate) and without catalyst at the temperatures of 250, 275 and 300 °C. The produced liquids at 300 °C in supercritical liquefaction were analyzed and characterized by elemental, GC-MS and FT-IR. 36 and 37 different types of compounds were identified by GC-MS obtained in acetone and ethanol respectively.

  13. Extraction of atrazine and its metabolites using supercritical fluids and enhanced-fluidity liquids

    PubMed

    Shows; Olesik

    2000-09-01

    Supercritical fluid and enhanced-fluidity liquid extractions are performed on spiked sediment samples containing atrazine (ATRA) and five of its metabolites including desisopropyldesethylatrazine, desethylhydroxyatrazine (DEHA), desisopropylatrazine, desethylatrazine, and hydroxyatrazine (HA). The hydroxylated metabolites are of particular interest because of their increased water solubility and the fact that their high polarity makes them difficult to analyze. Soxhlet extractions using methanol are conducted for the purpose of comparison. Results of the extractions show that the hydroxy-containing metabolites of ATRA are not effectively extracted with supercritical CO2 alone. The solvating or desorbing power of carbon dioxide appears too low to extract HA and DEHA. The extraction recoveries of the hydroxylated metabolites increase when enhanced-fluidity liquid mixtures of methanol/CO2 are used, and these rates increase with the methanol concentration. Enhanced-fluidity ternary liquid mixtures of H2O/methanol/CO2 yield the best recoveries for these compounds. ATRA recoveries are equally effective when using supercritical CO2 or enhanced-fluidity mixtures. The other nonhydroxy-containing metabolites require the increased solvent strength of either large percentages of methanol in CO2 or ternary mixtures of H2O, methanol, and CO2 for high recoveries. Recoveries with enhanced-fluidity liquid ternary mixtures are better than the recoveries from Soxhlet for all the compounds in the study. PMID:11011724

  14. Formation of curcumin nanoparticles via solution-enhanced dispersion by supercritical CO2.

    PubMed

    Zhao, Zheng; Xie, Maobin; Li, Yi; Chen, Aizheng; Li, Gang; Zhang, Jing; Hu, Huawen; Wang, Xinyu; Li, Shipu

    2015-01-01

    In order to enhance the bioavailability of poorly water-soluble curcumin, solution-enhanced dispersion by supercritical carbon dioxide (CO2) (SEDS) was employed to prepare curcumin nanoparticles for the first time. A 2(4) full factorial experiment was designed to determine optimal processing parameters and their influence on the size of the curcumin nanoparticles. Particle size was demonstrated to increase with increased temperature or flow rate of the solution, or with decreased precipitation pressure, under processing conditions with different parameters considered. The single effect of the concentration of the solution on particle size was not significant. Curcumin nanoparticles with a spherical shape and the smallest mean particle size of 325 nm were obtained when the following optimal processing conditions were adopted: P = 20 MPa, T = 35°C, flow rate of solution = 0.5 mL·min(-1), concentration of solution = 0.5%. Fourier transform infrared (FTIR) spectroscopy measurement revealed that the chemical composition of curcumin basically remained unchanged. Nevertheless, X-ray powder diffraction (XRPD) and thermal analysis indicated that the crystalline state of the original curcumin decreased after the SEDS process. The solubility and dissolution rate of the curcumin nanoparticles were found to be higher than that of the original curcumin powder (approximately 1.4 μg/mL vs 0.2 μg/mL in 180 minutes). This study revealed that supercritical CO2 technologies had a great potential in fabricating nanoparticles and improving the bioavailability of poorly water-soluble drugs. PMID:25995627

  15. Formation of curcumin nanoparticles via solution-enhanced dispersion by supercritical CO2

    PubMed Central

    Zhao, Zheng; Xie, Maobin; Li, Yi; Chen, Aizheng; Li, Gang; Zhang, Jing; Hu, Huawen; Wang, Xinyu; Li, Shipu

    2015-01-01

    In order to enhance the bioavailability of poorly water-soluble curcumin, solution-enhanced dispersion by supercritical carbon dioxide (CO2) (SEDS) was employed to prepare curcumin nanoparticles for the first time. A 24 full factorial experiment was designed to determine optimal processing parameters and their influence on the size of the curcumin nanoparticles. Particle size was demonstrated to increase with increased temperature or flow rate of the solution, or with decreased precipitation pressure, under processing conditions with different parameters considered. The single effect of the concentration of the solution on particle size was not significant. Curcumin nanoparticles with a spherical shape and the smallest mean particle size of 325 nm were obtained when the following optimal processing conditions were adopted: P =20 MPa, T =35°C, flow rate of solution =0.5 mL·min−1, concentration of solution =0.5%. Fourier transform infrared (FTIR) spectroscopy measurement revealed that the chemical composition of curcumin basically remained unchanged. Nevertheless, X-ray powder diffraction (XRPD) and thermal analysis indicated that the crystalline state of the original curcumin decreased after the SEDS process. The solubility and dissolution rate of the curcumin nanoparticles were found to be higher than that of the original curcumin powder (approximately 1.4 μg/mL vs 0.2 μg/mL in 180 minutes). This study revealed that supercritical CO2 technologies had a great potential in fabricating nanoparticles and improving the bioavailability of poorly water-soluble drugs. PMID:25995627

  16. Low-temperature, selective catalytic deoxygenation of vegetable oil in supercritical fluid media.

    PubMed

    Kim, Seok Ki; Lee, Hong-Shik; Hong, Moon Hyun; Lim, Jong Sung; Kim, Jaehoon

    2014-02-01

    The effects of supercritical fluids on the production of renewable diesel-range hydrocarbons from natural triglycerides were investigated. Various supercritical fluids, which included CO2 (scCO2 ), propane (scC3 H8 ) and n-hexane (scC6 H14 ), were introduced with H2 and soybean oil into a fixed-bed reactor that contained pre-activated CoMo/γ-Al2 O3 . Among these supercritical fluids, scC3 H8 and scC6 H14 efficiently allowed the reduction of the reaction temperature by as much as 50 °C as a result of facilitated heat and mass transfer and afforded similar yields to reactions in the absence of supercritical fluids. The compositional analyses of the gas and liquid products indicated that the addition of scC3 H8 during the hydrotreatment of soybean oil promoted specific deoxygenation pathways, decarbonylation and decarboxylation, which consumed less H2 than the hydrodeoxygenation pathway. As a result, the quantity of H2 required to obtain a high yield of diesel-range hydrocarbons could be reduced to 57 % if scC3 H8 was used. As decarboxylation and decarbonylation are mildly endothermic reactions, the reduced heat transfer resistance in scC3 H8 may drive the deoxygenation reaction to thermodynamically favourable pathways. PMID:24339322

  17. The influence of water and supercritical CO2 on the frictional strength and velocity dependence of montmorillonite and muscovite and the potential for fault zone reactivation in CO2 storage reservoirs

    NASA Astrophysics Data System (ADS)

    Samuelson, Jon

    2013-04-01

    Recent research indicates that CO2 is capable of inducing swelling in clay minerals in a similar fashion to water, though to a more modest extent. It is therefore of importance for feasibility studies of the geological storage of CO2 to understand if the addition of CO2 to clay rich fault zones has the potential to cause significant frictional weakening, similar to that associated with water. We conduct velocity-stepping direct shear experiments on pre-pressed plates (49 mm long x 35 mm wide x ~1 mm thick), of montmorillonite and muscovite. An effective normal stress of 35 MPa is used in all experiments, which is roughly equivalent to the effective overburden stress expected in many storage projects. Temperature was held constant at ~48 °C, consistent with previous experiments which indicated CO2 induced swelling in montmorillonite. Pore fluid conditions are the main variable in this suite of experiments, in which the frictional strength of each clay mineral is analyzed oven-dry (attached to vacuum), saturated with deionized (DI) water, and oven-dry saturated with supercritical CO2. Pore pressure is maintained at 15 MPa for the water and CO2 saturated experiments (?n=50 MPa, PH20-CO2=15 MPa). Shearing velocity is varied systematically from approximately 11 μm/s to 0.2, 1.1, 11, 1.1, and 0.2 μm/s in order to determine the rate and state friction parameters, a, b, and DC. Additionally, microstructural analysis of the post-shear clay gouges is conducted in an effort to understand the rheology behind changes observed in frictional properties. Preliminary results of experiments on montmorillonite show an overconsolidation peak at strains of approximately 0.3 for each of the oven-dry and water and CO2 saturated experiments. Peak friction (μP) for oven-dry montmorillonite is 0.53, decaying to a steady state friction (μSS) of 0.51. For DI-saturated montmorillonite μP=0.11 and μSS=0.10. CO2-saturated montmorillonite displays frictional strength between that of dry

  18. The influence of water and supercritical CO2 on the frictional strength and velocity dependence of swelling (montmorillonite and saponite) and non-swelling (muscovite and illite) clays and the potential for fault zone reactivation in CO2 storage reservoirs

    NASA Astrophysics Data System (ADS)

    Samuelson, J. E.

    2012-12-01

    Recent research indicates that CO2 is capable of inducing swelling in clay minerals in a similar fashion to water, though to a more modest extent. It is therefore of importance for feasibility studies of the geological storage of CO2 to understand if the addition of CO2 to clay rich fault zones has the potential to cause significant frictional weakening, similar to that associated with water. We conduct velocity-stepping direct shear experiments on pre-pressed plates (49 mm long x 35 mm wide x ~1 mm thick), of montmorillonite and saponite, both known swelling clays, as well as plates of illite and muscovite also important phyllosilicate minerals in faults, though non-swelling. An effective normal stress of 35 MPa is used in all experiments, which is roughly equivalent to the effective overburden stress expected in many storage projects. Temperature was held constant at ~ 48 °C, consistent with previous experiments which indicated CO2 induced swelling in montmorillonite. Pore fluid conditions are the main variable in this suite of experiments, in which the frictional strength of each clay mineral is analyzed dry (open to atmospheric conditions), saturated with deionized (DI) water, and saturated with supercritical CO2. Pore pressure is maintained at 15 MPa for the water and CO2 saturated experiments (σn=50 MPa, PH20/CO2=15 MPa). Shearing velocity is varied systematically from approximately 11 μm/s to 0.2, 1.1, 11, 1.1, and 0.2 μm/s in order to determine the rate and state friction parameters, a, b, and DC. Additionally, microstructural analysis of the post-shear clay gouges is conducted in an effort to understand the rheology behind changes observed in frictional properties. Initial experiments on montmorillonite show an overconsolidation peak at strains of approximately 0.3 for each of the dry and water and CO2 saturated experiments. Peak friction (μP) for dry montmorillonite is 0.18, decaying to a steady state friction (μss) of 0.13. For DI

  19. Optimization of Supercritical CO2 Extraction of Fish Oil from Viscera of African Catfish (Clarias gariepinus)

    PubMed Central

    Sarker, Mohamed Zaidul Islam; Selamat, Jinap; Habib, Abu Sayem Md. Ahsan; Ferdosh, Sahena; Akanda, Mohamed Jahurul Haque; Jaffri, Juliana Mohamed

    2012-01-01

    Fish oil was extracted from the viscera of African Catfish using supercritical carbon dioxide (SC-CO2). A Central Composite Design of Response Surface methodology (RSM) was employed to optimize the SC-CO2 extraction parameters. The oil yield (Y) as response variable was executed against the four independent variables, namely pressure, temperature, flow rate and soaking time. The oil yield varied with the linear, quadratic and interaction of pressure, temperature, flow rate and soaking time. Optimum points were observed within the variables of temperature from 35 °C to 80 °C, pressure from 10 MPa to 40 MPa, flow rate from 1 mL/min to 3 mL/min and soaking time from 1 h to 4 h. However, the extraction parameters were found to be optimized at temperature 57.5 °C, pressure 40 MPa, flow rate 2.0 mL/min and soaking time 2.5 h. At this optimized condition, the highest oil yields were found to be 67.0% (g oil/100 g sample on dry basis) in the viscera of catfish which was reasonable to the yields of 78.0% extracted using the Soxhlet method. PMID:23109854

  20. Experimental investigation of buoyancy effects on convection heat transfer of supercritical CO2 flow in a horizontal tube

    NASA Astrophysics Data System (ADS)

    Tanimizu, Katsuyoshi; Sadr, Reza

    2016-04-01

    The heat transfer characteristics of supercritical carbon dioxide (S-CO2) turbulent flow were investigated experimentally in a horizontal circular pipe with an inner diameter of 8.7 mm. Local convection coefficients and Nusselt numbers of the flow were obtained at different locations along the pipe with a constant heat flux ranging from 16 to 64 kW/m2. Experiments were performed for fluid mass flow rate ranging from 0.011 to 0.017 kg/s, an inlet fluid temperature ranging from 24 to 28 °C, and a flow pressure ranging from 7.5 to 9.0 MPa to investigate their effects on the convection heat transfer in the pipe. Both enhancement as well as deterioration in the heat transfer coefficient was observed for the flow conditions examined in this work. Experimental results were then compared with the widely used empirical correlation for pipe flow. Three commonly used buoyancy parameters were utilized to investigate their applicability in the present test conditions. Results indicate that all the parameters show a strong presence of buoyancy effects in the present test conditions. The trend and magnitude of these parameters, however, do not agree with the trend and magnitude of heat transfer enhancement and deterioration along the pipe.

  1. Thermally and Acoustically Driven Transport in Supercritical Fluids

    NASA Astrophysics Data System (ADS)

    Hasan, Nusair Mohammed Ibn

    Supercritical fluids are fluids at temperature and pressure above their respective critical values. Such fluids are increasingly being used in power generation, refrigeration and chemical process industry. The objectives of the current research were to develop a fundamental understanding of the transport phenomena in near-critical supercritical fluids via high-resolution numerical simulations and careful experiments for improved design of industrial processes and applications that employ supercritical fluids. A set of synergistic experimental and numerical studies were proposed in this research. Four main focus areas under the broad spectrum of supercritical fluid transport were chosen -- (a) characterization of thermoacoustic transport, (b) interaction of thermoacoustic transport with natural convection, (c) characterization of acoustically augmented transport and (d) enhancement of mass transport using acoustic waves. A numerical model to simulate thermoacoustic convection in near-critical fluids was developed. In the computational model, the conservation equations were solved along with a real-fluid equation of state for supercritical fluid and variable thermo-physical properties. Thermoacoustic waves in near-critical carbon dioxide were also investigated experimentally on acoustic time scales using a fast response measurement system. The predicted results from the calculation and the measurements provide interesting details regarding the thermal transport mechanisms at near-critical states. The numerical model was applied to investigate the interaction of buoyancy driven flows with thermoacoustic convection in near-critical supercritical fluids. This model can be extensively used for studying the steady-state thermal transport and stability behavior of near-critical fluids. Mechanically driven acoustic waves in supercritical fluid generated by a vibrating wall in a cylindrical resonator were studied both numerically and experimentally. The simulations revealed

  2. HYDROGENATION OF 4-OXOISOPHORONE OVER PD/AL2/O2 CATALYST UNDER SUPERCRITICAL CO2 MEDIUM

    EPA Science Inventory

    Hydrogenation of 4-oxoisophorone has been studied over 1% Pd/Al2O3 impregnated catalyst in supercritical CO2 medium at different reaction conditions. The effect of temperature, pressure and reaction medium on the conversion and product selectivity is discussed. Phase behavior stu...

  3. SUPERCRITICAL FLUID EXTRACTION OF TOXIC HEAVY METALS FROM SOLID AND AQUEOUS MATRICES

    SciTech Connect

    Wang, S; Lin, Yuehe; Wai, C M.

    2003-04-09

    The feasibility of using dithiocarbamate chelating agents or sulfur-containing organophosphorus reagents for the supercritical fluid extraction (SFE) of toxic heavy metals from solid and aqueous matrices is investigated. Effective extraction of heavy metal ions from both sand matrix and water samples was demonstrated by using supercritical CO2 containing dithiocarbamatechelating agents. A commercially available sulfur-containing organophosphorus reagent, Cyanex 302, was used for the extraction of toxic heavy metals from wood samples. The extraction profiles were initially rapid followed by a very low level of metal extraction, indicating that the process is limited to extraction of leachable toxic metals.

  4. Significant Improvement of Thermal Stability for CeZrPrNd Oxides Simply by Supercritical CO2 Drying

    PubMed Central

    Fan, Yunzhao; Wang, Zizi; Xin, Ying; Li, Qian; Zhang, Zhaoliang; Wang, Yingxia

    2014-01-01

    Pr and Nd co-doped Ce-Zr oxide solid solutions (CZPN) were prepared using co-precipitation and microemulsion methods. It is found that only using supercritical CO2 drying can result in a significant improvement of specific surface area and oxygen storage capacity at lower temperatures for CZPN after aging at 1000°C for 12 h in comparison with those using conventional air drying and even supercritical ethanol drying. Furthermore, the cubic structure was obtained in spite of the fact that the atomic ratio of Ce/(Ce+Zr+Pr+Nd) is as low as 29%. The high thermal stability can be attributed to the loosely aggregated morphology and the resultant Ce enrichment on the nanoparticle surface, which are caused by supercritical CO2 drying due to the elimination of surface tension effects on the gas-liquid interface. PMID:24516618

  5. Significant improvement of thermal stability for CeZrPrNd oxides simply by supercritical CO(2) drying.

    PubMed

    Fan, Yunzhao; Wang, Zizi; Xin, Ying; Li, Qian; Zhang, Zhaoliang; Wang, Yingxia

    2014-01-01

    Pr and Nd co-doped Ce-Zr oxide solid solutions (CZPN) were prepared using co-precipitation and microemulsion methods. It is found that only using supercritical CO(2) drying can result in a significant improvement of specific surface area and oxygen storage capacity at lower temperatures for CZPN after aging at 1000°C for 12 h in comparison with those using conventional air drying and even supercritical ethanol drying. Furthermore, the cubic structure was obtained in spite of the fact that the atomic ratio of Ce/(Ce+Zr+Pr+Nd) is as low as 29%. The high thermal stability can be attributed to the loosely aggregated morphology and the resultant Ce enrichment on the nanoparticle surface, which are caused by supercritical CO(2) drying due to the elimination of surface tension effects on the gas-liquid interface. PMID:24516618

  6. Implementing stationary-phase optimized selectivity in supercritical fluid chromatography.

    PubMed

    Delahaye, Sander; Lynen, Frédéric

    2014-12-16

    The performance of stationary-phase optimized selectivity liquid chromatography (SOS-LC) for improved separation of complex mixtures has been demonstrated before. A dedicated kit containing column segments of different lengths and packed with different stationary phases is commercially available together with algorithms capable of predicting and ranking isocratic and gradient separations over vast amounts of possible column combinations. Implementation in chromatographic separations involving compressible fluids, as is the case in supercritical fluid chromatography, had thus far not been attempted. The challenge of this approach is the dependency of solute retention with the mobile-phase density, complicating linear extrapolation of retention over longer or shorter columns segments, as is the case in conventional SOS-LC. In this study, the possibilities of performing stationary-phase optimized selectivity supercritical fluid chromatography (SOS-SFC) are demonstrated with typical low density mobile phases (94% CO2). The procedure is optimized with the commercially available column kit and with the classical isocratic SOS-LC algorithm. SOS-SFC appears possible without any density correction, although optimal correspondence between prediction and experiment is obtained when isopycnic conditions are maintained. As also the influence of the segment order appears significantly less relevant than expected, the use of the approach in SFC appears as promising as is the case in HPLC. Next to the classical use of SOS for faster baseline separation of all solutes in a mixture, the benefits of the approach for predicting as wide as possible separation windows around to-be-purified solutes in semipreparative SFC are illustrated, leading to significant production rate improvements in (semi)preparative SFC. PMID:25393519

  7. A two-step supercritical fluid extraction of polycyclic aromatic hydrocarbons from roadside soil samples.

    PubMed

    Lojková, Lea; Sedláková, Jitka; Kubán, Vlastimil

    2005-11-01

    A two-step procedure for the supercritical fluid extraction (SFE) of polycyclic aromatic hydrocarbons from soil samples was developed. The procedure consists of a static supercritical fluid treatment in a closed extraction cell at a high temperature (T=250 or 340degreesC for 20 min) and an SFE with a solvent trapping. During the static phase, the sample is exposed to a supercritical organic solvent (methanol, toluene, dichloromethane, ACN, acetone, and hexane). The solvent penetrates particles of the matrix to substitute strongly bonded molecules and dissolves the analytes in the supercritical phase. At ambient temperature, supercritical fluids became liquid and lost their solvation abilities. Most of the analytes condense on the surface of the particles or on the extraction cell walls without forming strong bonds or penetrating deep into the matrix. Thus, the pretreatment liberates the analytes and they behave similar to those in freshly spiked samples. The common SFE with toluene-modified CO2 as an extraction fluid follows the static phase. With the use of the most suitable extraction phases (toluene, ACN), the extraction efficiency of the combined procedure is much higher (approximately100%). The results of the combined procedure are compared to the SFE procedure of the same untreated sample (difference less than 5%) and to the Soxhlet extraction. The extracts were analyzed using a GC with the flame ionization detection. PMID:16318201

  8. Brucite [Mg(OH 2)] carbonation in wet supercritical CO 2: An in situ high pressure X-ray diffraction study

    NASA Astrophysics Data System (ADS)

    Schaef, H. T.; Windisch, C. F.; McGrail, B. P.; Martin, P. F.; Rosso, K. M.

    2011-12-01

    Understanding mechanisms and kinetics of mineral carbonation reactions relevant to sequestering carbon dioxide as a supercritical fluid (scCO 2) in geologic formations is crucial to accurately predicting long-term storage risks. Most attention so far has been focused on reactions occurring between silicate minerals and rocks in the aqueous dominated CO 2-bearing fluid. However, water-bearing scCO 2 also comprises a reactive fluid, and in this situation mineral carbonation mechanisms are poorly understood. Using in situ high-pressure X-ray diffraction, the carbonation of brucite [Mg(OH) 2] in wet scCO 2 was examined at pressure (82 bar) as a function of water concentration and temperature (50 and 75 °C). Exposing brucite to anhydrous scCO 2 at either temperature resulted in little or no detectable reaction over three days. However, addition of trace amounts of water resulted in partial carbonation of brucite into nesquehonite [MgCO 3·3H 2O] within a few hours at 50 °C. By increasing water content to well above the saturation level of the scCO 2, complete conversion of brucite into nesquehonite was observed. Tests conducted at 75 °C resulted in the conversion of brucite into magnesite [MgCO 3] instead, apparently through an intermediate nesquehonite step. Raman spectroscopy applied to brucite reacted with 18O-labeled water in scCO 2 show it was incorporated into carbonate at a relatively high concentration. This supports a carbonation mechanism with at least one step involving a direct reaction between the mineral and water molecules without mediation by a condensed aqueous layer.

  9. Investigation of Wyoming Bentonite Hydration in Dry to Water-Saturated Supercritical CH4 and CH4/CO2 Mixtures: Implications for CO2-Enhanced Gas Production

    NASA Astrophysics Data System (ADS)

    Loring, J.

    2015-12-01

    Injection of CO2 into low permeability shale formations leads to additional gas recovery and reduces the flux of CO2 into the atmosphere, thus combining a strong economic incentive with a permanent storage option for CO2. Reduced formation transmissivity due to clay swelling is a concern in CO2-enhanced gas production. Clay minerals partly determine the physical (i.e. permeability, brittleness) and certain chemical properties (i.e. wetting ability, gas adsorption) of shales, and montmorillonites are of particular interest because they swell by the uptake of species in their interlayer. In this study, the hydration and expansion of Na-, Cs-, and NH4+-saturated montmorillonite (Na-, Cs-, and NH4-SWy-2) in high-pressure (90 bar) and moderate temperature (50 °C) methane, carbon dioxide, and CO2/CH4 mixtures (3 and 25 mole% CO2) were investigated using in situ IR spectroscopic titrations, in situ XRD, in situ MAS-NMR, and ab initio electronic structure calculations. The overarching goal was to better understand the hydration/expansion behavior of Na-SWy-2 in CO2/CH4 fluid mixtures by comparison to Cs-, and NH4+-saturated clays. Specific aims were to (1) determine if CH4 intercalates the clays, (2) probe the effects of increasing dissolved CO2 and H2O concentrations, and (3) understand the role of cation solvation by H2O and/or CO2. In pure CH4, no evidence of CH4 intercalation was detected by IR for any of the clays. Similarly, no measurable changes to the basal spacing were observed by XRD in the presence of pure CH4. However, when dry Cs- and NH4-SWy-2 were exposed to dry fluids containing CO2, IR showed maximum CO2 penetrated the interlayer, XRD indicated the clays expanded, and NMR showed evidence for cation solvation by CO2, in line with theoretical predictions. IR titration of these clays with water showed sorbed H2O concentrations decreased with increasing dissolved CO2, suggesting competition for interlayer residency by CO2 and H2O. For Na-SWy-2, on the other

  10. Fluid dynamic effects on precision cleaning with supercritical fluids

    SciTech Connect

    Phelps, M.R.; Hogan, M.O.; Silva, L.J.

    1994-06-01

    Pacific Northwest Laboratory staff have assembled a small supercritical fluids parts cleaning test stand to characterize how system dynamics affect the efficacy of precision cleaning with supercritical carbon dioxide. A soiled stainless steel coupon, loaded into a ``Berty`` autoclave, was used to investigate how changes in system turbulence and solvent temperature influenced the removal of test dopants. A pulsed laser beam through a fiber optic was used to investigate real-time contaminant removal. Test data show that cleaning efficiency is a function of system agitation, solvent density, and temperature. These data also show that high levels of cleaning efficiency can generally be achieved with high levels of system agitation at relatively low solvent densities and temperatures. Agitation levels, temperatures, and densities needed for optimal cleaning are largely contaminant dependent. Using proper system conditions, the levels of cleanliness achieved with supercritical carbon dioxide compare favorably with conventional precision cleaning methods. Additional research is currently being conducted to generalize the relationship between cleaning performance and parameters such as contaminant solubilities, mass transfer rates, and solvent agitation. These correlations can be used to optimize cleaning performance, system design, and time and energy consumption for particular parts cleaning applications.

  11. Clay hydration/dehydration in dry to water-saturated supercritical CO2: Implications for caprock integrity

    SciTech Connect

    Loring, John S.; Schaef, Herbert T.; Thompson, Christopher J.; Turcu, Romulus VF; Miller, Quin R.; Chen, Jeffrey; Hu, Jian Z.; Hoyt, David W.; Martin, Paul F.; Ilton, Eugene S.; Felmy, Andrew R.; Rosso, Kevin M.

    2013-01-01

    Injection of supercritical CO2 (scCO2) for the geologic storage of carbon dioxide will displace formation water, and the pore space adjacent to overlying caprocks could eventually be dominated by dry to water-saturated scCO2. Wet scCO2 is highly reactive and capable of carbonating and hydrating certain minerals, whereas anhydrous scCO2 can dehydrate water-containing minerals. Because these geochemical processes affect solid volume and thus porosity and permeability, they have the potential to affect the long-term integrity of the caprock seal. In this study, we investigate the swelling and shrinkage of an expandable clay found in caprock formations, montmorillonite (Ca-STx-1), when exposed to variable water-content scCO2 at 50 °C and 90 bar using a combination of in situ probes, including X-ray diffraction (XRD), in situ magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR), and in situ attenuated total reflection infrared spectroscopy (ATR-IR). We show that the extent of montmorillonite clay swelling/shrinkage is dependent not only on water hydration/dehydration, but also on CO2 intercalation reactions. Our results also suggest a competition between water and CO2 for interlayer residency where increasing concentrations of intercalated water lead to decreasing concentrations of intercalated CO2. Overall, this paper demonstrates the types of measurements required to develop fundamental knowledge that will enhance modeling efforts and reduce risks associated with subsurface storage of CO2.

  12. Interaction Between CO2-Rich Sulfate Solutions and Carbonate Reservoir Rocks from Atmospheric to Supercritical CO2 Conditions: Experiments and Modeling

    NASA Astrophysics Data System (ADS)

    Cama, J.; Garcia-Rios, M.; Luquot, L.; Soler Matamala, J. M.

    2014-12-01

    A test site for CO2 geological storage is situated in Hontomín (Spain) with a reservoir rock that is mainly composed of limestone. During and after CO2 injection, the resulting CO2-rich acid brine gives rise to the dissolution of carbonate minerals (calcite and dolomite) and gypsum (or anhydrite at depth) may precipitate since the reservoir brine contains sulfate. Experiments using columns filled with crushed limestone or dolostone were conducted under different P-pCO2 conditions (atmospheric: 1-10-3.5 bar; subcritical: 10-10 bar; and supercritical: 150-34 bar), T (25, 40 and 60 ºC) and input solution compositions (gypsum-undersaturated and gypsum-equilibrated solutions). We evaluated the effect of these parameters on the coupled reactions of calcite/dolomite dissolution and gypsum/anhydrite precipitation. The CrunchFlow and PhreeqC (v.3) numerical codes were used to perform reactive transport simulations of the experiments. Under the P-pCO2-T conditions, the volume of precipitated gypsum was smaller than the volume of dissolved carbonate minerals, yielding an increase in porosity (Δporosity up to ≈ 4%). A decrease in T favored limestone dissolution regardless of pCO2 owing to increasing undersaturation with decreasing temperature. However, gypsum precipitation was favored at high T and under atmospheric pCO2 conditions but not at high T and under 10 bar of pCO2 conditions. The increase in limestone dissolution with pCO2 was directly attributed to pH, which was more acidic at higher pCO2. Increasing pCO2, carbonate dissolution occurred along the column whereas it was localized in the very inlet under atmospheric conditions. This was due to the buffer capacity of the carbonic acid, which maintains pH at around 5 and keeps the solution undersaturated with respect to calcite and dolomite along the column. 1D reactive transport simulations reproduced the experimental data (carbonate dissolution and gypsum precipitation for different P-pCO2-T conditions). Drawing

  13. Functionalization of polycaprolactone/hydroxyapatite scaffolds with Usnea lethariiformis extract by using supercritical CO2.

    PubMed

    Fanovich, M A; Ivanovic, J; Zizovic, I; Misic, D; Jaeger, P

    2016-01-01

    Investigation of an integrated supercritical fluid extraction and supercritical solvent impregnation process for fabrication of microporous polycaprolactone-hydroxyapatite (PCL-HA) scaffolds with antibacterial activity is presented. The HA content and particle size as well as the operating conditions of the integrated process is optimized regarding the amount of impregnated antibacterial agent (Usnea lethariiformis extract) in the PCL-HA matrix, scaffold morphology and antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA) strains. High pressure differential scanning calorimetry (HP-DSC) assay reveals that an increasing amount of HA results in decreasing melting temperature as well as crystallinity at an operating pressure of 17 MPa. The PCL-HA composites with micrometric sizes of the HA particles are convenient for being processed by the integrated process due to the simple preparation, a good interaction between the PCL matrix and filler and the advantageous impact on sorption. The scaffold obtained from PCL-HA with 20% of the HA shows the highest impregnation yield at 17 MPa and 35 °C (5.9%) and subsequently also the best bactericidal effect on the tested MRSA strains at an initial bacterial inoculum of 2 × 10(-4)CFU/mL. PMID:26478304

  14. Supercritical CO2 Extraction of Porogen Phase: An Alternative Route to Nanoporous Dielectrics

    SciTech Connect

    Lubguban, J.

    2004-11-04

    We present a supercritical CO{sub 2} (SCCO{sub 2}) process for the preparation of nanoporous organosilicate thin films for ultra low dielectric constant materials. The porous structure was generated by SCCO{sub 2} extraction of a sacrificial poly(propylene glycol) (PPG) from a nanohybrid film, where the nanoscopic domains of PPG porogen are entrapped within the crosslinked poly(methylsilsesquioxane) (PMSSQ) matrix. As a comparison, porous structures generated by both the usual thermal decomposition (at ca. 450 C) and by a SCCO{sub 2} process for 25 wt% and 55 wt% porogen loadings were evaluated. It is found that the SCCO{sub 2} process is effective in removing the porogen phase at relatively low temperatures (< 200 C) through diffusion of the supercritical fluid into the phase-separated nanohybrids and selective extraction of the porogen phase. Pore morphologies generated from the two methods are compared from representative three-dimensional (3D) images built from small angle x-ray scattering (SAXS) data.

  15. Reactive fluid transport in CO2 reservoir caprocks: constraints from scientific drilling of a natural CO2 reservoir

    NASA Astrophysics Data System (ADS)

    Kampman, N.; Bickle, M. J.; Bertier, P.; Busch, A.; Chapman, H.; Evans, J. P.; Graham, C.; Harrington, J.; Maskell, A.

    2013-12-01

    The long-term performance of reservoir caprocks in geological CO2 storage sites remains uncertain due to the poorly constrained nature of field-scale fluid-mineral reaction kinetics and CO2 transport processes in low permeability rocks. Predicting the nature, rates and impacts of CO2 penetration into the caprocks from numerical modelling studies maybe undermined by their reliance on laboratory derived reaction kinetics from short-term experiments, and the complexity of the coupled reactive transport processes at the nano- and micro-scale. We report here on the early results from scientific drilling and laboratory analysis of the caprocks of a stacked sequence of natural CO2 reservoir at Green River, Utah. In summer 2012, diamond drilling to a depth of 325m, adjacent to a CO2 degassing normal fault recovered core from two major CO2 reservoirs in the Entrada and Navajo Sandstones and from the intervening Carmel Formation regional caprock. In-situ pH, CO2 concentrations and fluid element and isotope geochemistry were determined from wireline downhole sampling of pressurized fluids from the reservoirs. The fluid geochemistry provides important constraints on reservoir filling by flow of CO2-charged brines through the fault damage zone, macro-scale fluid flow in the reservoirs and the state of fluid-mineral thermodynamic disequilibrium from which the nature of the fluid-mineral reactions can be interpreted. Mineralogical, geochemical and petrophysical profiles through portions of the caprocks in contact with the CO2-charged reservoirs have been used to constrain the nature and penetration depths of the CO2-promoted fluid-mineral reaction fronts. The major reactions are the dissolution of diagenetic dolomite cements and hematite grain coatings which generate porosity in the caprocks. Analysis of the generated pore structure from a variety of analytical techniques will be discussed. Stable C- and O-isotopic shifts in the composition of the carbonate cements record their

  16. Tectonic impact on the dynamics of CO2-rich fluid migration in Utah

    NASA Astrophysics Data System (ADS)

    Nadine, E. Z.; Jean Luc, F.; Remy, D.; Battani, A.; Olivier, V.

    2009-12-01

    explain the existence of these distinct provinces? Is it due to the physical properties of the reservoirs, to the evolution of the fracture and fault patterns changing through time in connection with paleostress fields, to the occurrence of a thick salt pillow in the Moab area which has driven the tectonic style and played as local seal, to the shale sealing properties when PCO2 increased at depth to the physical phase of the CO2 during migration or storage (dissolved, super-critical or gas), or finally to the seismic cyclicity. A possible strong linkage between the seismicity and the volcanic activity, corresponding to large CO2-rich gas expel, have been investigated. In order to constrain the architecture of the deep buried reservoirs and traps we analyzed the deformation through analogue models, the models have been acquired with X-Ray tomography at IFP. These parameters have been analysed for the three investigated areas, allowing to propose an integrated model of the local circulation and/or storage of the CO2-enriched fluid for each area.

  17. Supercritical CO2 direct cycle Gas Fast Reactor (SC-GFR) concept.

    SciTech Connect

    Wright, Steven Alan; Parma, Edward J., Jr.; Suo-Anttila, Ahti Jorma; Al Rashdan, Ahmad; Tsvetkov, Pavel Valeryevich; Vernon, Milton E.; Fleming, Darryn D.; Rochau, Gary Eugene

    2011-05-01

    This report describes the supercritical carbon dioxide (S-CO{sub 2}) direct cycle gas fast reactor (SC-GFR) concept. The SC-GFR reactor concept was developed to determine the feasibility of a right size reactor (RSR) type concept using S-CO{sub 2} as the working fluid in a direct cycle fast reactor. Scoping analyses were performed for a 200 to 400 MWth reactor and an S-CO{sub 2} Brayton cycle. Although a significant amount of work is still required, this type of reactor concept maintains some potentially significant advantages over ideal gas-cooled systems and liquid metal-cooled systems. The analyses presented in this report show that a relatively small long-life reactor core could be developed that maintains decay heat removal by natural circulation. The concept is based largely on the Advanced Gas Reactor (AGR) commercial power plants operated in the United Kingdom and other GFR concepts.

  18. Hydroxyapatite-TiO(2)-based nanocomposites synthesized in supercritical CO(2) for bone tissue engineering: physical and mechanical properties.

    PubMed

    Salarian, Mehrnaz; Xu, William Z; Wang, Zhiqiang; Sham, Tsun-Kong; Charpentier, Paul A

    2014-10-01

    Calcium phosphate-based nanocomposites offer a unique solution toward producing scaffolds for orthopedic and dental implants. However, despite attractive bioactivity and biocompatibility, hydroxyapatite (HAp) has been limited in heavy load-bearing applications due to its intrinsically low mechanical strength. In this work, to improve the mechanical properties of HAp, we grew HAp nanoplates from the surface of one-dimensional titania nanorod structures by combining a coprecipitation and sol-gel methodology using supercritical fluid processing with carbon dioxide (scCO2). The effects of metal alkoxide concentration (1.1-1.5 mol/L), reaction temperature (60-80 °C), and pressure (6000-8000 psi) on the morphology, crystallinity, and surface area of the resulting nanostructured composites were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and Brunauer-Emmet-Teller (BET) method. Chemical composition of the products was characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge structure (XANES) analyses. HAp nanoplates and HAp-TiO2 nanocomposites were homogeneously mixed within poly(ε-caprolactone) (PCL) to develop scaffolds with enhanced physical and mechanical properties for bone regeneration. Mechanical behavior analysis demonstrated that the Young's and flexural moduli of the PCL/HAp-TiO2 composites were substantially higher than the PCL/HAp composites. Therefore, this new synthesis methodology in scCO2 holds promise for bone tissue engineering with improved mechanical properties. PMID:25184699

  19. Supercritical Fluid Extraction of Aflatoxin B 1 from Soil

    EPA Science Inventory

    This research describes the development of a Supercritical Fluid Extraction (SFE) method to recover aflatoxin B1 from fortified soil. The effects of temperature, pressure, modifier (identity and percentage), and extraction type were assessed. Using the optimized SFE conditions, ...

  20. Supercritical fluid carbon dioxide cleaning of plutonium parts

    SciTech Connect

    Hale, S.J.

    1991-12-31

    Supercritical fluid carbon dioxide is under investigation in this work for use as a cleaning solvent for the final cleaning of plutonium parts. These parts must be free of organic residue to avoid corrosion in the stockpile. Initial studies on stainless steel and full-scale mock-up parts indicate that the oils of interest are easily and adequately cleaned from the metal surfaces with supercritical fluid carbon dioxide. Results from compatibility studies show that undesirable oxidation or other surface reactions are not occurring during exposure of plutonium to the supercritical fluid. Cleaning studies indicate that the oils of interest are removed from the plutonium surface under relatively mild conditions. These studies indicate that supercritical fluid carbon dioxide is a very promising cleaning medium for this application.

  1. SUPERCRITICAL FLUID EXTRACTION OF PARTICULATE AND ADSORBENT MATERIALS. PART 2

    EPA Science Inventory

    The physical properties of supercritical fluids allow similar solvent strengths as liquids, but with higher diffusion coefficients, lower viscosities and an extended temperature range which provides the potential for more rapid and efficient extraction rates than possible with li...

  2. SUPERCRITICAL FLUID EXTRACTION OF PARTICULATE AND ADSORBENT MATERIALS

    EPA Science Inventory

    The report is a summary of work performed by PNL on the extraction of semivolatile organic materials (SVOCs), for example, polynuclear aromatic compounds, from various adsorbents and environmental matrices, using supercritical fluids (SCFs) as extractants. The results of the work...

  3. Optimized, Competitive Supercritical-CO2 Cycle GFR for Gen IV Service

    SciTech Connect

    M.J. Driscoll; P. Hejzlar; G. Apostolakis

    2008-09-08

    An overall plant design was developed for a gas-cooled fast reactor employing a direct supercritical Brayton power conversion system. The most important findings were that (1) the concept could be capital-cost competitive, but startup fuel cycle costs are penalized by the low core power density, specified in large part to satisfy the goal of significatn post-accident passive natural convection cooling; (2) active decay heat removal is preferable as the first line of defense, with passive performance in a backup role; (3) an innovative tube-in-duct fuel assembly, vented to the primpary coolant, appears to be practicable; and (4) use of the S-Co2 GFR to support hydrogen production is a synergistic application, since sufficient energy can be recuperated from the product H2 and 02 to allow the electrolysis cell to run 250 C hotter than the reactor coolant, and the water boilers can be used for reactor decay heat removal. Increasing core poer density is identified as the top priority for future work on GFRs of this type.

  4. Modeling of flow and heat transfer for fluids at supercritical conditions

    NASA Astrophysics Data System (ADS)

    Gallaway, Tara

    2011-12-01

    The Supercritical Water Reactor (SCWR) has been proposed as one of the six Generation IV reactor design concepts under consideration. The key feature of the SCWR is that water at supercritical pressures is used as the reactor coolant. At supercritical pressures, the working fluid does not undergo phase change as it is heated, but rather the fluid properties experience dramatic variations throughout what is known as the pseudo-critical region. Highly nonuniform temperature and uid property distributions are expected in the reactor core, which will have a significant impact on turbulence and heat transfer as well as stability limits for future SCWRs. The goal of this work is to understand and predict the effects of these fluid property variations on turbulence and heat transfer throughout the reactor core and to predict the potential onset of dynamic instabilities. CO2 at supercritical conditions is included in the current study due in some part to its use as a viable simulant fluid in place of water for experimental studies. The use of CO2 at supercritical conditions as a reactor coolant has also gained popularity in recent years. Spline-type property models have been developed for both water and CO2 at supercritical pressures in order to include the property variations into a numerical solver. Turbulence and heat transfer models for fluids at supercritical conditions have been developed and implemented into the NPHASE-CMFD computer code. The results of predictions using the proposed models have been compared to experimental data from the Korea Atomic Energy Research Institute (KAERI) for various heat transfer regimes. While no model is without some deficiency, the Chien Low-Reynolds k -- epsilon model performs best at predicting the experimental data. A stability model has been developed and is presented in this dissertation as well. This model utilizes three different solution methods and tests the effects of inlet temperature, mass flow rate, local loss

  5. High Density Thermal Energy Storage with Supercritical Fluids

    NASA Technical Reports Server (NTRS)

    Ganapathi, Gani B.; Wirz, Richard

    2012-01-01

    A novel approach to storing thermal energy with supercritical fluids is being investigated, which if successful, promises to transform the way thermal energy is captured and utilized. The use of supercritical fluids allows cost-affordable high-density storage with a combination of latent heat and sensible heat in the two-phase as well as the supercritical state. This technology will enhance penetration of several thermal power generation applications and high temperature water for commercial use if the overall cost of the technology can be demonstrated to be lower than the current state-of-the-art molten salt using sodium nitrate and potassium nitrate eutectic mixtures.

  6. Supercritical fluid extraction and bioactivity of cedarwood oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Supercritical carbon dioxide (70°C, 4,000 psi) was used to extract cedarwood oil from Eastern redcedar, Juniperus virginiana L. The CO2-derived oil was tested for biological activity against several species of arthropods, including mosquitoes, ticks, houseflies, and ants. The cedarwood oil was found...

  7. Processing energetic materials with supercritical fluid precipitation techniques

    NASA Astrophysics Data System (ADS)

    Essel, Jonathan

    cm 50% drop height instead of the standard 17 cm by ERL impact test) or ESD sensitivity (4 no-gos for NAWC ESD test) but showed a significant reduction towards initiation by friction (521 lbs threshold initiation level force instead of the standard 468 lbs by ABL friction test). The RESS-N process was used to coat nano-sized ALEX ® aluminum particles with RDX. Coatings were observed on the ALEX ® particles by field emission scanning electron microscopy (FE-SEM) and by energy dispersive X-ray spectroscopy (EDS). A method of injecting ALEX ® particles into the RDX/CO2 supercritical solution was developed that was effective in coating small batches with RDX.

  8. Supercritical CO2 Dissolution and Mass Transfer in a Heterogeneous Pore Network under Drainage and Imbibition Conditions

    NASA Astrophysics Data System (ADS)

    Kneafsey, T. J.; Chang, C.; Zhou, Q.; Oostrom, M.; Wietsma, T. W.; Yu, Q.

    2015-12-01

    Dissolution trapping of supercritical CO2 (scCO2) is usually modeled by assuming instantaneous scCO2 dissolution and equilibrium phase partitioning. Our recent core-scale imbibition experiments show a prolonged depletion of residual scCO2 by dissolution, implying a non-equilibrium mechanism. In our 2D sandstone-analogue micromodel experimental study, pore-scale scCO2 dissolution was inferred from imaging (1) drainage using a pH-sensitive water dye and (2) imbibition using a scCO2 dye. The drainage experiment was conducted by injecting scCO2 into the dissolved-CO2 (dsCO2)-free water-filled pore network. The time-lapse images of non-uniform dye intensities indicating varying pH show that dsCO2 concentration varies from zero to solubility in individual pores and pore clusters and the average concentration gradually increases with time. The different rates of dissolution in different pores/clusters can be attributed to (1) fast scCO2 dissolution at scCO2-water interfaces, (2) rate-limited mass transfer due to limited interface areas, and (3) a transition from rate-limited to diffusion-limited mass transfer, revealed by detailed analysis on selected pores and pore clusters. The imbibition experiments conducted by injecting deionized water at different rates show (1) water flow in channels bypassing scCO2 at high residual saturations, (2) subsequent, slow scCO2 depletion by dissolution and mass transfer as effluent dsCO2 concentration varies from 0.06% to 4.44% of solubility, and (3) creation of new water flow paths by dissolution, enhancing scCO2 depletion by coupled displacement and dissolution. Both the drainage and imbibitions experiments indicate non-equilibrium scCO2 dissolution in the centimeter-scale pore network over 4.5 hours and up to 14 hours, respectively. The pore-scale imaging can help better understand the effects of pore-throat characteristics on scCO2 dissolution and mass transfer during drainage and imbibition and the interplay between displacement and

  9. Antimicrobial activity and composition profile of grape (Vitis vinifera) pomace extracts obtained by supercritical fluids.

    PubMed

    Oliveira, Daniela A; Salvador, Ana Augusta; Smânia, Artur; Smânia, Elza F A; Maraschin, Marcelo; Ferreira, Sandra R S

    2013-04-10

    The possibility of increasing the aggregated value of the huge amount of residues generated by wineries around the world foment studies using the grape pomace - the residue from the wine production, composed by seed, skin and stems - to obtain functional ingredients. Nowadays, consumers in general prefer natural and safe products mainly for food and cosmetic fields, where the supercritical fluid extraction is of great importance due to the purity of the extracts provided. Therefore, the objective of this work is to evaluate the global extraction yield, the antimicrobial activity and the composition profile of Merlot and Syrah grape pomace extracts obtained by supercritical CO2 (SC-CO2) and CO2 added with co-solvent at pressures up to 300 bar and temperatures of 50 and 60 °C. The results were compared with the ones obtained by Soxhlet and by ultrasound-assisted leaching extraction methods. The main components from the extracts, identified by HPLC, were gallic acid, p-OH-benzoic acid, vanillic acid and epicatechin. The antibacterial and antifungal activities of the extracts were evaluated using four strains of bacteria (Staphylococcus aureus, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa) and three fungi strains (Candida albicans, Candida parapsilosis, Candida krusei). Despite lower extraction yield results, the supercritical fluid extracts presented the highest antimicrobial effectiveness compared to the other grape pomace extracts due to the presence of antimicrobial active compounds. Syrah extracts were less efficient against the microorganisms tested and Merlot extracts were more active against Gram-positive bacteria. PMID:23036924

  10. Dewetting of silica surfaces upon reactions with supercritical CO2 and brine: pore-scale studies in micromodels.

    PubMed

    Kim, Yongman; Wan, Jiamin; Kneafsey, Timothy J; Tokunaga, Tetsu K

    2012-04-01

    Wettability of reservoir minerals and rocks is a critical factor controlling CO(2) mobility, residual trapping, and safe-storage in geologic carbon sequestration, and currently is the factor imparting the greatest uncertainty in predicting capillary behavior in porous media. Very little information on wettability in supercritical CO(2) (scCO(2))-mineral-brine systems is available. We studied pore-scale wettability and wettability alteration in scCO(2)-silica-brine systems using engineered micromodels (transparent pore networks), at 8.5 MPa and 45 °C, over a wide range of NaCl concentrations up to 5.0 M. Dewetting of silica surfaces upon reactions with scCO(2) was observed through water film thinning, water droplet formation, and contact angle increases within single pores. The brine contact angles increased from initial values near 0° up to 80° with larger increases under higher ionic strength conditions. Given the abundance of silica surfaces in reservoirs and caprocks, these results indicate that CO(2) induced dewetting may have important consequences on CO(2) sequestration including reducing capillary entry pressure, and altering quantities of CO(2) residual trapping, relative permeability, and caprock integrity. PMID:22404561

  11. Initial assessment of Ni-base alloy performance in 0.1 MPa and supercritical CO2

    DOE PAGESBeta

    Pint, B. A.; Keiser, J. R.

    2015-09-25

    There is considerable interest in increasing the working temperature of both open and closed supercritical CO2 (sCO2) cycles to ≥700 °C. At these temperatures, it is unlikely that any Fe-base alloys have suitable strength and therefore the focus is on Ni-base alloys for this application. To begin addressing the lack of compatibility data under these conditions, initial work exposed a wide range of candidate alloys in 500-h exposures at 20 MPa (200 bar) CO2 at 650 -750 °C in high purity CO2. In general, the reaction products were thin and protective in these exposures. A smaller group of alloy couponsmore » focusing on chromia- and alumina-forming alloys was exposed for 500h in 0.1 MPa (1bar) air, CO2, CO2+O2 and CO2+H2O for comparison. Thus, the thin surface oxides formed were very similar to those formed at high pressure and no clear detrimental effect of CO2 oxidation or O2 or H2O impurities could be observed in these exposures.« less

  12. Particle Formation by Supercritical Fluid Extraction and Expansion Process

    PubMed Central

    Zhou, Junbo; Li, Haiting; Quan, Can

    2013-01-01

    Supercritical fluid extraction and expansion (SFEE) patented technology combines the advantages of both supercritical fluid extraction (SFE) and rapid expansion of supercritical solution (RESS) with on-line coupling, which makes the nanoparticle formation feasible directly from matrix such as Chinese herbal medicine. Supercritical fluid extraction is a green separation technology, which has been developed for decades and widely applied in traditional Chinese medicines or natural active components. In this paper, a SFEE patented instrument was firstly built up and controlled by LABVIEW work stations. Stearic acid was used to verify the SFEE process at optimized condition; via adjusting the preexpansion pressure and temperature one can get different sizes of particles. Furthermore, stearic acid was purified during the SFEE process with HPLC-ELSD detecting device; purity of stearic acid increased by 19%, and the device can purify stearic acid. PMID:24223031

  13. Development and Validation of Multidimensional Models of Supercritical CO2 Energy Conversion Systems for Nuclear Power Reactors

    SciTech Connect

    Podowski, Michael Z.

    2015-01-22

    A general objective of this project was to develop, verify and validate mechanistic multidimensional models of local flow and heat transfer in supercritical carbon dioxide (S-CO2) devices and systems, and to demonstrate the application of the new models to selected components of S-CO2 nuclear energy transport systems. Both steady-state and time-dependent operating conditions have been investigated. The overall workscope consisted of the following three major parts: Development, testing and validation of a mechanistic model of forced-convection heat transfer in heated channels cooled using S-CO2 at slightly supercritical pressures; Development, testing and verification/validation of a new model of the dynamics of closed- loop S-CO2 heat transport systems; and, Formulation, testing and verification of a mechanistic model for the analysis of flow and pressure distribution in S-CO2 compressors. The results of the work performed for the project have been documented in several publications.

  14. A man-portable supercritical fluid extractor

    SciTech Connect

    Wright, B.W.; Zemanian, T.S.; Lee, R.N.; Wright, C.W.

    1995-12-31

    A new prototype supercritical fluid extraction (SFE) apparatus has been developed for the on-site preparation of solid matrix samples for subsequent organic analysis. The apparatus consists of two parts, each of which satisfy weight and size requirements for portability. They are a generator module that supplies high-pressure carbon dioxide (the source of which is dry ice) and a briefcase containing a pressure regulator, extraction cells, valves for flow control, flow restriction hardware, equipment for sample collection, temperature control devices, and ancillary supplies. The generator module provides carbon dioxide at pressures to 1 kbar ({approximately}14,500 psi), incorporates no moving parts, and allows rapid loading without tools due to novel fingertight closures. Samples are contained in sintered inserts that fit inside three extraction cells that also have rapid, fingertight closures. Analyte collection may be accomplished using liquid solvent or restrictorless rapid depressurization techniques. Control schemes allow operation at a wide variety of pressures and temperatures and the use of static, dynamic, or hybrid static/dynamic extraction strategies. The technical performance of the prototype apparatus was evaluated by comparison of results from the SFE of a soil sample spiked with six to nine organic compounds of environmental interest to Soxhlet extraction.

  15. A man-portable supercritical fluid extractor

    SciTech Connect

    Wright, B.W.; Zemanian, T.S.; Lee, R.N.; Wright, C.W.

    1995-02-01

    A new prototype supercritical fluid extraction (SFE) apparatus has been developed for the on-site preparation of solid matrix samples for subsequent organic analysis. The apparatus consists of two parts, each of which satisfy weight and size requirements for portability. They are a generator module that supplies high-pressure carbon dioxide (the source of which is dry ice) and a briefcase containing a pressure regulator, extraction cells, valves for flow control, flow restriction hardware, equipment for sample collection, temperature control devices, and ancillary supplies. The generator module provides carbon dioxide at pressures to 1 kbar ({approximately}14,500 psi), incorporates no moving parts, and allows rapid loading without tools due to novel fingertight closures. Samples are contained in sintered inserts that fit inside three extraction cells that also have rapid, fingertight closures. Analyte collection can be accomplished using liquid solvent or restrictorless rapid depressurization techniques. Control schemes allow operation at a wide variety of pressures and temperatures and the use of static, dynamic, or hybrid static/dynamic extraction strategies. The technical performance of the prototype apparatus was evaluated by comparison of results from the SFE of a soil sample spiked with six to nine organic compounds of environmental interest to Soxhlet extraction.

  16. In Situ Study of CO2 and H2O Partitioning Between Na-Montmorillonite and Variably Wet Supercritical Carbon Dioxide

    SciTech Connect

    Loring, John S.; Ilton, Eugene S.; Chen, Jeffrey; Thompson, Christopher J.; Martin, Paul F.; Benezeth, Pascale; Rosso, Kevin M.; Felmy, Andrew R.; Schaef, Herbert T.

    2014-06-03

    Shale formations play fundamental roles in large-scale geologic carbon sequestration (GCS) aimed primarily to mitigate climate change, and in smaller-scale GCS targeted mainly for CO2-enhanced gas recovery operations. In both technologies, CO2 is injected underground as a supercritical fluid (scCO2), where interactions with shale minerals could influence successful GCS implementation. Reactive components of shales include expandable clays, such as montmorillonites and mixed-layer illite/smectite clays. In this work, we used in situ X-ray diffraction (XRD) and in situ infrared (IR) spectroscopy to investigate the swelling/shrinkage and water/CO2 sorption of a pure montmorillonite, Na-SWy-2, when the clay is exposed to variably hydrated scCO2 at 50 °C and 90 bar. Measured interlayer spacings and sorbed water concentrations at varying levels of scCO2 hydration are similar to previously reported values measured in air at ambient pressure over a range of relative humidities. IR spectra show evidence of both water and CO2 intercalation, and variations in peak shapes and positions suggest multiple sorbed types with distinct chemical environments. Based on the intensity of the asymmetric CO stretching band of the CO2 associated with the Na-SWy-2, we observed a significant increase in sorbed CO2 as the clay expands from a 0W to a 1W state, suggesting that water props open the interlayer so that CO2 can enter. However, as the clay transitions from a 1W to a 2W state, CO2 desorbs sharply. These observations were placed in the context of two conceptual models concerning hydration mechanisms for expandable clays and were also discussed in light of recent theoretical studies on CO2-H2O-clay interactions. The swelling/shrinkage of expandable clays could affect solid volume, porosity, and permeability of shales. Consequently, the results from this work could aid predictions of shale caprock integrity in large-scale GCS, as well as methane transmissivity in enhanced gas recovery

  17. Enabling the measurement of in-situ, atomic scale mineral transformation rates in supercritical CO2 through development of a high pressure AFM

    NASA Astrophysics Data System (ADS)

    Lea, S.; Higgins, S. R.; Knauss, K. G.; Rosso, K. M.

    2010-12-01

    Capture and storage of carbon dioxide in deep geologic formations represents one promising scenario for minimizing the impacts of greenhouse gases on global warming. The ability to demonstrate that CO2 will remain stored in the geological formation over the long-term is needed in support of widespread implementation decisions, and knowledge of mineral-fluid chemical transformation rates is an essential aspect. The majority of previous research on mineral-fluid interactions has focused primarily on the reactivity of minerals in aqueous solutions containing various amounts of dissolved CO2. Long-term caprock integrity, however, could also be dictated by mineral transformations occurring in low-water environments dominated by the supercritical CO2 (scCO2) fluid phase, which is expected to slowly displace or dessicate residual aqueous solution at the caprock-fluid interface. Many of the mechanisms of mineral interfacial reactions with hydrated or water-saturated scCO2 are unknown and there are unique challenges to obtain kinetic and thermodynamic data for mineral transformation reactions in these fluids. We are developing a high-pressure atomic force microscope (AFM) that will enable in-situ, atomic scale measurements of metal carbonate nucleation and growth rates on mineral surfaces in contact with hydrated scCO2 fluids. This apparatus is based on the hydrothermal AFM that was developed by Higgins et al.1, but includes some enhancements and is designed to handle pressures up to 100 bar. The noise in our optically-based cantilever deflection detection scheme is subject to perturbations in the density (due to index of refraction dependence) of the compressible supercritical fluid. Consequently, variations in temperature and pressure within the fluid cell are a primary technical challenge with possible significant impact in imaging resolution. We demonstrate with our test fluid cell that the equivalent rms noise in the deflection signal is similar to (and in some cases

  18. Investigation of parameter estimation and impact of injection rate on relative permeability measurements for supercritical CO2 and water by unsteady-state method

    NASA Astrophysics Data System (ADS)

    Hiratsuka, Y.; Yamamoto, H.

    2014-12-01

    CCS (Carbon dioxide Capture and Storage) is a promising option for mitigating climate changes. To predict the behavior of injected CO2 in a deep reservoir, relative permeability of supercritical CO2 and water of the reservoir rock is one of the most fundamental and influential properties. For determining the relative permeability, we employed the unsteady state method, in which the relative permeability is determined based on history matching of transient monitoring data with a multi-phase flow model. The unsteady-state method is relatively simple and short, but obviously its accuracy strongly depends on the flow model assumed in the history matching. In this study, we conducted relative permeability measurements of supercritical CO2-water system for Berea sandstone with the unsteady-state method under a reservoir condition at a 1km depth (P= 9.5MPa, T = 44˚C). Automatic history matching was performed with an inversion simulator iTOUGH2/ECO2N for multi-phase flow system of supercritical CO2, NaCl, and water. A sensitivity analysis of relative permeability parameters for CO2 and water was carried out to better understand the uniqueness and the uncertainty of the optimum solution estimated by the history matching. Among the parameters of the Corey-type curve employed in this study, while the end-point permeability could be optimized in a limited range, the other parameters were correlated and their combinations were not unique. However it was found that any combination of these parameters results in nearly identical shapes of the curve in the range of CO2 saturation in this study (0 to 60%). The optimally estimated curve from the unsteady-method was well comparable with those from the steady-state method acquired in the previous studies. Our experiment also focuses on the impact of injection rate on the estimates of relative permeability, as it is known that the injection rate could have a significant effect on fluid distribution such as viscous fingering with

  19. Optimization of Operation Parameters for Helical Flow Cleanout with Supercritical CO2 in Horizontal Wells Using Back-Propagation Artificial Neural Network.

    PubMed

    Song, Xianzhi; Peng, Chi; Li, Gensheng; He, Zhenguo; Wang, Haizhu

    2016-01-01

    Sand production and blockage are common during the drilling and production of horizontal oil and gas wells as a result of formation breakdown. The use of high-pressure rotating jets and annular helical flow is an effective way to enhance horizontal wellbore cleanout. In this paper, we propose the idea of using supercritical CO2 (SC-CO2) as washing fluid in water-sensitive formation. SC-CO2 is manifested to be effective in preventing formation damage and enhancing production rate as drilling fluid, which justifies tis potential in wellbore cleanout. In order to investigate the effectiveness of SC-CO2 helical flow cleanout, we perform the numerical study on the annular flow field, which significantly affects sand cleanout efficiency, of SC-CO2 jets in horizontal wellbore. Based on the field data, the geometry model and mathematical models were built. Then a numerical simulation of the annular helical flow field by SC-CO2 jets was accomplished. The influences of several key parameters were investigated, and SC-CO2 jets were compared to conventional water jets. The results show that flow rate, ambient temperature, jet temperature, and nozzle assemblies play the most important roles on wellbore flow field. Once the difference between ambient temperatures and jet temperatures is kept constant, the wellbore velocity distributions will not change. With increasing lateral nozzle size or decreasing rear/forward nozzle size, suspending ability of SC-CO2 flow improves obviously. A back-propagation artificial neural network (BP-ANN) was successfully employed to match the operation parameters and SC-CO2 flow velocities. A comprehensive model was achieved to optimize the operation parameters according to two strategies: cost-saving strategy and local optimal strategy. This paper can help to understand the distinct characteristics of SC-CO2 flow. And it is the first time that the BP-ANN is introduced to analyze the flow field during wellbore cleanout in horizontal wells. PMID

  20. Optimization of Operation Parameters for Helical Flow Cleanout with Supercritical CO2 in Horizontal Wells Using Back-Propagation Artificial Neural Network

    PubMed Central

    Song, Xianzhi; Peng, Chi; Li, Gensheng

    2016-01-01

    Sand production and blockage are common during the drilling and production of horizontal oil and gas wells as a result of formation breakdown. The use of high-pressure rotating jets and annular helical flow is an effective way to enhance horizontal wellbore cleanout. In this paper, we propose the idea of using supercritical CO2 (SC-CO2) as washing fluid in water-sensitive formation. SC-CO2 is manifested to be effective in preventing formation damage and enhancing production rate as drilling fluid, which justifies tis potential in wellbore cleanout. In order to investigate the effectiveness of SC-CO2 helical flow cleanout, we perform the numerical study on the annular flow field, which significantly affects sand cleanout efficiency, of SC-CO2 jets in horizontal wellbore. Based on the field data, the geometry model and mathematical models were built. Then a numerical simulation of the annular helical flow field by SC-CO2 jets was accomplished. The influences of several key parameters were investigated, and SC-CO2 jets were compared to conventional water jets. The results show that flow rate, ambient temperature, jet temperature, and nozzle assemblies play the most important roles on wellbore flow field. Once the difference between ambient temperatures and jet temperatures is kept constant, the wellbore velocity distributions will not change. With increasing lateral nozzle size or decreasing rear/forward nozzle size, suspending ability of SC-CO2 flow improves obviously. A back-propagation artificial neural network (BP-ANN) was successfully employed to match the operation parameters and SC-CO2 flow velocities. A comprehensive model was achieved to optimize the operation parameters according to two strategies: cost-saving strategy and local optimal strategy. This paper can help to understand the distinct characteristics of SC-CO2 flow. And it is the first time that the BP-ANN is introduced to analyze the flow field during wellbore cleanout in horizontal wells. PMID

  1. Deposition of Ni nanoparticles onto porous supports using supercritical CO2: effect of the precursor and reduction methodology.

    PubMed

    Morère, Jacobo; Royuela, Sergio; Asensio, Guillermo; Palomino, Pablo; Enciso, Eduardo; Pando, Concepción; Cabañas, Albertina

    2015-12-28

    The deposition of Ni nanoparticles into porous supports is very important in catalysis. In this paper, we explore the use of supercritical CO(2) (scCO(2)) as a green solvent to deposit Ni nanoparticles on mesoporous SiO2 SBA-15 and a carbon xerogel. The good transport properties of scCO(2) allowed the efficient penetration of metal precursors dissolved in scCO(2) within the pores of the support without damaging its structure. Nickel hexafluoroacetylacetonate hydrate, nickel acetylacetonate, bis(cyclopentadienyl)nickel, Ni(NO(3))2⋅6H(2)O and NiCl(2)⋅6H(2)O were tried as precursors. Different methodologies were used: impregnation in scCO(2) and reduction in H(2)/N(2) at 400°C and low pressure, reactive deposition using H(2) at 200-250°C in scCO(2) and reactive deposition using ethanol at 150-200°C in scCO(2). The effect of precursor and methodology on the nickel particle size and the material homogeneity (on the different substrates) was analysed. This technology offers many opportunities in the preparation of metal-nanostructured materials. PMID:26574525

  2. New Linear Partitioning Models Based on Experimental Water: Supercritical CO2 Partitioning Data of Selected Organic Compounds.

    PubMed

    Burant, Aniela; Thompson, Christopher; Lowry, Gregory V; Karamalidis, Athanasios K

    2016-05-17

    Partitioning coefficients of organic compounds between water and supercritical CO2 (sc-CO2) are necessary to assess the risk of migration of these chemicals from subsurface CO2 storage sites. Despite the large number of potential organic contaminants, the current data set of published water-sc-CO2 partitioning coefficients is very limited. Here, the partitioning coefficients of thiophene, pyrrole, and anisole were measured in situ over a range of temperatures and pressures using a novel pressurized batch-reactor system with dual spectroscopic detectors: a near-infrared spectrometer for measuring the organic analyte in the CO2 phase and a UV detector for quantifying the analyte in the aqueous phase. Our measured partitioning coefficients followed expected trends based on volatility and aqueous solubility. The partitioning coefficients and literature data were then used to update a published poly parameter linear free-energy relationship and to develop five new linear free-energy relationships for predicting water-sc-CO2 partitioning coefficients. A total of four of the models targeted a single class of organic compounds. Unlike models that utilize Abraham solvation parameters, the new relationships use vapor pressure and aqueous solubility of the organic compound at 25 °C and CO2 density to predict partitioning coefficients over a range of temperature and pressure conditions. The compound class models provide better estimates of partitioning behavior for compounds in that class than does the model built for the entire data set. PMID:27081725

  3. Identification of Fragile Microscopic Structures during Mineral Transformations in Wet Supercritical CO2

    SciTech Connect

    Arey, Bruce W.; Kovarik, Libor; Qafoku, Odeta; Wang, Zheming; Hess, Nancy J.; Felmy, Andrew R.

    2013-04-01

    In this study we examine the nature of highly fragile reaction products that form in low water content super critical carbon dioxide (scCO2) using a combination of scanning electron microscopy/focus ion beam (SEM/FIB), confocal Raman spectroscopy, helium ion microscopy (HeIM), and transmission electron microscopy (TEM). HeIM images show these precipitates to be fragile rosettes that can readily decompose even under slight heating from an electron beam. Using the TEM revealed details on the interfacial structure between the newly formed surface precipitates and the underlying initial solid phases. The detailed microscopic analysis revealed that the growth of the precipitates either followed a tip growth mechanism with precipitates forming directly on the forsterite surface if the initial solid was non-porous (natural forsterite) or growth from the surface of the precipitates where fluid was conducted through the porous (nanoforsterite) agglomerates to the growth center. The mechanism of formation of the hydrated/hydroxylated magnesium carbonate compound (HHMC) phases offers insight into the possible mechanisms of carbonate mineral formation from scCO2 solutions which has recently received a great deal of attention as the result of the potential for CO2 to act as an atmospheric greenhouse gas and impact overall global warming. The techniques used here to examine these fragile structures an also be used to examine a wide range of fragile material surfaces. SEM and FIB technologies have now been brought together in a single instrument, which represents a powerful combination for the studies in biological, geological and materials science.

  4. Supercritical fluid technology: a promising approach in pharmaceutical research.

    PubMed

    Girotra, Priti; Singh, Shailendra Kumar; Nagpal, Kalpana

    2013-02-01

    Supercritical fluids possess the unique properties of behaving like liquids and gases, above their critical point. Supercritical fluid technology has recently emerged as a green and novel technique for various processes such as solubility enhancement of poorly soluble drugs, plasticization of polymers, surface modification, nanosizing and nanocrystal modification, and chromatographic extraction. Research interest in this area has been fuelled because of the numerous advantages that the technology offers over the conventional methods. This work aims to review the merits, demerits, and various processes such as rapid expansion of supercritical solutions (RESS), particles from gas saturated solutions (PGSS), gas antisolvent process (GAS), supercritical antisolvent process (SAS) and polymerization induced phase separation (PIPS), that have enabled this technology to considerably raise the interest of researchers over the past two decades. An insight has been given into the numerous applications of this technology in pharmaceutical industry and the future challenges which must be appropriately dealt with to make it effective on a commercial scale. PMID:23036159

  5. Design of experiments for enantiomeric separation in supercritical fluid chromatography.

    PubMed

    Landagaray, Elodie; Vaccher, Claude; Yous, Saïd; Lipka, Emmanuelle

    2016-02-20

    A new chiral melatoninergic ligand, potentially successor of Valdoxan(®), presenting an improved pharmacological profile with regard to agomelatine, was chosen as a probe for a supercritical fluid chromatographic separation carried-out on an amylose tris[(S)-1-α-methylbenzylcarbamate] based stationary phase. The goal of this work was to optimize simultaneously three factors identified to have a significant influence to obtain the best resolution in the shortest analysis time (i.e., retention time of the second eluting enantiomer) for this chiral compound. For this purpose a central circumscribed composite (CCC) design was developed with three factors: the flow-rate, the pressure outlet and the percentage of ethanol to optimize of two responses: shortest analysis time and best resolution. The optimal conditions obtained via the optimizer mode of the software (using the Nelder-Mead method) i.e., CO2/EtOH 86:14 (v:v), 104bar, 3.2mLmin(-1) at 35°C lead to a resolution of 3.27 in less than 6min. These conditions were transposed to a preparative scale where a concentrated methanolic solution of 40mM was injected with a sample loop of 100μL. This step allowed to separate an amount of around 65mg of racemic melatonin ligand in only 3h with impressive yields (97%) and enantiomeric excess (99.5%). PMID:26765267

  6. Supercritical fluid extraction of free amino acids from broccoli leaves.

    PubMed

    Arnáiz, E; Bernal, J; Martín, M T; Nozal, M J; Bernal, J L; Toribio, L

    2012-08-10

    The extraction of free amino acids (AAs) from broccoli leaves using supercritical fluid extraction (SFE) with CO(2) modified with methanol, is presented in this work. The effect of the different variables was studied, showing the percentage of methanol a strong influence on the extraction. The best results in terms of extraction yield were obtained at 250 bar, 70°C, 35% methanol as organic modifier, a flow rate of 2 mL/min, and 5 min and 30 min as static and dynamic extraction times, respectively. The extraction yield obtained with the SFE method was comparable to that obtained employing conventional solvent extraction with methanol-water (70:30) and minor than using water, but the relative proportion of the AAs in the extracts was very different. For example, the use of SFE allowed the enrichment in proline and glutamine of the extracts. The selected conditions were applied to obtain SFE extracts of broccoli leaves from different varieties (Naxos, Nubia, Marathon, Parthenon and Viola). The highest levels of AAs were found in the SFE extracts from the Nubia variety. PMID:22608777

  7. Using Combined X-ray Computed Tomography and Acoustic Resonance to Understand Supercritical CO2 Behavior in Fractured Sandstone

    NASA Astrophysics Data System (ADS)

    Kneafsey, T. J.; Nakagawa, S.

    2015-12-01

    Distribution of supercritical (sc) CO2 has a large impact on its flow behavior as well as on the properties of seismic waves used for monitoring. Simultaneous imaging of scCO2 distribution in a rock core using X-ray computed tomography (CT) and measurements of seismic waves in the laboratory can help understand how the distribution evolves as scCO2 invades through rock, and the resulting seismic signatures. To this end, we performed a series of laboratory scCO2 core-flood experiments in intact and fractured anisotropic Carbon Tan sandstone samples. In these experiments, we monitored changes in the CO2 saturation distribution and sonic-frequency acoustic resonances (yielding both seismic velocity and attenuation) over the course of the floods. A short-core resonant bar test system (Split-Hopkinson Resonant Bar Apparatus) custom fit into a long X-ray transparent pressure vessel was used for the seismic measurements, and a modified General Electric medical CT scanner was used to acquire X-ray CT data from which scCO2 saturation distributions were determined. The focus of the experiments was on the impact of single fractures on the scCO2 distribution and the seismic properties. For this reason, we examined several cases including 1. intact, 2. a closely mated fracture along the core axis, 3. a sheared fracture along the core axis (both vertical and horizontal for examining the buoyancy effect), and 4. a sheared fracture perpendicular to the core axis. For the intact and closely mated fractured cores, Young's modulus declined with increasing CO2 saturation, and attenuation increased up to about 15% CO2 saturation after which attenuation declined. For cores having wide axial fractures, the Young's modulus was lower than for the intact and closely mated cases, however did not change much with CO2 pore saturation. Much lower CO2 pore saturations were achieved in these cases. Attenuation increased more rapidly however than for the intact sample. For the core

  8. Flow behaviour of supercritical CO2 and brine in Berea sandstone during drainage and imbibition revealed by medical X-ray CT images

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Nishizawa, Osamu; Kiyama, Tamotsu; Chiyonobu, Shun; Xue, Ziqiu

    2014-06-01

    We injected Berea sandstone with supercritical CO2 and imaged the results with a medical X-ray computed tomography (CT) scanner. The images were acquired by injecting CO2 into a core of brine-saturated sandstone (drainage), and additional images were acquired during reinjection of brine (imbibition) after drainage. We then analysed the temporal variations of CO2 saturation maps obtained from the CT images. The experiments were performed under a confining pressure of 12 MPa, a pore pressure of 10 MPa and a temperature of 40 °C. Porosity and CO2 saturation were calculated for each image voxel of the rock on the basis of the Hounsfield unit values (CT numbers) measured at three states of saturation: dry, full brine saturation and full CO2 saturation. The saturation maps indicated that the distributions of CO2 and brine were controlled by the sub-core-scale heterogeneities which consisted of a laminated structure (bedding) with high- and low-porosity layers. During drainage, CO2 preferentially flowed through the high-porosity layers where most of the CO2 was entrapped during low flow-rate imbibition. The entrapped CO2 was flushed out when high flow-rate imbibition commenced. Plots of the voxel's CT number against porosity revealed the relationship between fluid replacement and porosity. By reference to the CT numbers at the full brine-saturated stage, differential CT numbers were classified into three bins corresponding to voxel porosity: high, medium and low porosity. Distributions of the differential CT number for the three porosity bins were bimodal and in order with respect to the porosity bins during both drainage and imbibitions; however, the order differed between the two stages. This difference suggested that different replacement mechanisms operated for the two processes. Spatial autocorrelation of CO2 saturation maps on sections perpendicular to the flow direction revealed remarkable changes during passage of the replacement fronts during both drainage and

  9. Micro-PIV measurements of multiphase flow of water and supercritical CO2 in 2D heterogeneous porous micromodels

    NASA Astrophysics Data System (ADS)

    Li, Y.; Kazemifar, F.; Blois, G.; Christensen, K. T.

    2015-12-01

    Multiphase flow of water and supercritical carbon dioxide (CO2) in porous media is central to geological sequestration of CO2 into saline aquifers. However, our fundamental understanding of the coupled flow dynamics of CO2 and water in complex geologic media still remains limited, especially at the pore scale. Recently, studies have been carried out in 2D homogeneous models with the micro-PIV technique, yielding very interesting observations of pore-scale flow transport. The primary aim of this work is to leverage this experimental protocol to quantify the pore-scale flow of water and liquid/supercritical CO2 in 2D heterogeneous porous micromodels under reservoir-relevant conditions. The goal is to capture the dynamics of this multi-phase flow in a porous matrix that mimics the heterogeneity of natural rock. Fluorescent microscopy and the micro-PIV technique are employed to simultaneously measure the spatially-resolved instantaneous velocity field in the water and quantify the instantaneous spatial configuration of both phases. The results for heterogeneous micromodels will be presented and compared with those for homogeneous micromodels, yielding valuable insight into flow processes at the pore scale in natural rock.

  10. Supercritical Fluid Chromatography/Fourier Transform Infrared Spectroscopy Of Food Components

    NASA Astrophysics Data System (ADS)

    Calvey, Elizabeth M.; Page, Samuel W.; Taylor, Larry T.

    1989-12-01

    Supercritical fluid (SF) technologies are being investigated extensively for applications in food processing. The number of SF-related patents issued testifies to the level of interest. Among the properties of materials at temperatures and pressures above their critical points (supercritical fluids) is density-dependent solvating power. Supercritical CO2 is of particular interest to the food industry because of its low critical temperature (31.3°C) and low toxicity. Many of the components in food matrices react or degrade at elevated temperatures and may be adversely affected by high temperature extractions. Likewise, these components may not be amenable to GC analyses. Our SF research has been in the development of methods employing supercritical fluid chromatography (SFC) and extraction (SFE) coupled to a Fourier transform infrared (FT-IR) spectrometer to investigate food composition. The effects of processing techniques on the isomeric fatty acid content of edible oils and the analysis of lipid oxidation products using SFC/FT-IR with a flow-cell interface are described.

  11. Molecular modeling studies of interfacial reactions in wet supercritical CO2.

    NASA Astrophysics Data System (ADS)

    Glezakou, V.; McGrail, B. P.; Windisch, C. F.; Schaef, H. T.; Martin, P.

    2011-12-01

    In the recent years, Carbon Capture and Sequestration (CCS) technologies have gained considerable momentum in a globally organized effort to mitigate greenhouse emissions and adverse climate change. Co-sequestration refers to the capture and geologic sequestration of carbon dioxide and minor contaminants (sulfur compounds, NOx, Hg, etc.) in subsurface formations. Cosequestration offers the potential to make carbon management more economically acceptable to industry relative to sequestration of pure CO2. This may be achieved through significant savings in plant (and retrofit) capital cost, operating cost, and energy savings as well by eliminating the need for one or more individual pollutant capture systems (such as SO2 scrubbers). The latter point is important because co-sequestration may result in a net positive impact to the environment through avoided loss of power generation capacity from parasitic loads and reduced fuel needs. This paper will discuss our research on modeling, imaging and characterization of cosequestration processes and reactivity at a fundamental level. Our work examines the interactions of CO2-rich fluids with metal and mineral surfaces, and how these are affected by the presence of other gas components (e.g. SO2, H2O or NOx) commonly present in the CO2 streams. We have found that reactivity is also affected by the composition of the surface or, less obviously, by the surface exposed, for example, (104) vs (100 )of carbonate minerals. We combine experimental techniques such as XRD and Raman spectroscopy, which can detect and follow reactive processes, with ab initio modeling methods based on density functional theory, to establish a reliable correspondence between theory and experiment with predictive capability. Analysis of our molecular dynamics simulations, reveals structural information and vibrational density of states that can directly compare with XRD measurements and vibrational spectroscopy. While reactivity in CO2-containing

  12. Asphaltene reaction via supercritical fluid extraction

    SciTech Connect

    Deo, M.D.; Hanson, F.V.

    1993-03-01

    Supercritical fluid extraction (SFE) of bitumen was carried out in a continuous extractor using propane as the solvent at several temperatures and pressures. The asphaltene contents of the residual fractions in the extractor were compared to the asphaltene content of the original bitumen. Asphaltenes were defined as pentane insolubles in this study. It was found that the absolute asphaltene content of the residual fractions exceeded the asphaltene content of the original bitumen. Even when the asphaltene content was prorated by the weight percent of the residual material, it was found to be higher than the original asphaltene content. The data established that the types of compounds separating as asphaltenes changed as the nature of the mixture was altered by SFE. The data also indicated that it may be inappropriate to perform asphaltene material balances to assess the amount of precipitate. The original asphaltene content of a bitumen that is undergoing compositional changes in a sequence of operations may not be an accurate measure of the precipitating tendency of the bitumen in production and processing operations. The asphaltene content of the residual material varied depending on the extraction conditions and was as much as 3--5 times the original asphaltene content. The asphaltene content of the residual material was a maximum at the most efficient extraction condition which was in the vicinity of the critical temperature of propane. The H/C atomic ratio of the residual fractions was lower compared to the original bitumen, indicating that the ratio of polar to nonpolar compounds may also be important from precipitation considerations. Saturate and aromatic compounds were preferentially extracted and the ratio of asphaltenes to resins increased in the residual fractions relative to the original bitumen.

  13. Asphaltene reaction via supercritical fluid extraction

    SciTech Connect

    Deo, M.D.; Hanson, F.V.

    1993-01-01

    Supercritical fluid extraction (SFE) of bitumen was carried out in a continuous extractor using propane as the solvent at several temperatures and pressures. The asphaltene contents of the residual fractions in the extractor were compared to the asphaltene content of the original bitumen. Asphaltenes were defined as pentane insolubles in this study. It was found that the absolute asphaltene content of the residual fractions exceeded the asphaltene content of the original bitumen. Even when the asphaltene content was prorated by the weight percent of the residual material, it was found to be higher than the original asphaltene content. The data established that the types of compounds separating as asphaltenes changed as the nature of the mixture was altered by SFE. The data also indicated that it may be inappropriate to perform asphaltene material balances to assess the amount of precipitate. The original asphaltene content of a bitumen that is undergoing compositional changes in a sequence of operations may not be an accurate measure of the precipitating tendency of the bitumen in production and processing operations. The asphaltene content of the residual material varied depending on the extraction conditions and was as much as 3--5 times the original asphaltene content. The asphaltene content of the residual material was a maximum at the most efficient extraction condition which was in the vicinity of the critical temperature of propane. The H/C atomic ratio of the residual fractions was lower compared to the original bitumen, indicating that the ratio of polar to nonpolar compounds may also be important from precipitation considerations. Saturate and aromatic compounds were preferentially extracted and the ratio of asphaltenes to resins increased in the residual fractions relative to the original bitumen.

  14. Particle Formation and Product Formulation Using Supercritical Fluids.

    PubMed

    Knez, Željko; Knez Hrnčič, Maša; Škerget, Mojca

    2015-01-01

    Traditional methods for solids processing involve either high temperatures, necessary for melting or viscosity reduction, or hazardous organic solvents. Owing to the negative impact of the solvents on the environment, especially on living organisms, intensive research has focused on new, sustainable methods for the processing of these substances. Applying supercritical fluids for particle formation may produce powders and composites with special characteristics. Several processes for formation and design of solid particles using dense gases have been studied intensively. The unique thermodynamic and fluid-dynamic properties of supercritical fluids can be used also for impregnation of solid particles or for the formation of solid powderous emulsions and particle coating, e.g., for formation of solids with unique properties for use in different applications. We give an overview of the application of sub- and supercritical fluids as green processing media for particle formation processes and present recent advances and trends in development. PMID:26091976

  15. Enhanced coal liquefaction by pyrolysis in supercritical fluids

    SciTech Connect

    Paulaitis, M.E.; Klein, M.T.; Sandler, S.I.

    1990-11-19

    A fundamental investigation of a novel coal liquefaction process was undertaken which combines pyrolysis and supercritical-fluid solvent extraction. The experimental work consisted of determining: (1) coal pyrolysis reaction pathways, kinetics and mechanisms; (2) equilibrium solubilities of coal-related compounds in supercritical water. Experiments involving model coal compounds (tetralin and 1-methylnaphthalene, phenethyl phenyl ether, 1,3-diphenylpropane, benzyl phenyl ether, benzylamine). 8 refs., 6 figs., 9 tabs.

  16. Thermal analysis of turbulent flow of a supercritical fluid

    NASA Technical Reports Server (NTRS)

    Yamane, E.

    1979-01-01

    The influence of the large variation of thermodynamics and transport properties near the pseudocritical temperature on the heat transfer coefficient of supercritical fluid in turbulent flow was studied. The formation of the characteristics peak in the heat transfer coefficient vs. bulk temperature curve is described, and the necessity of the fluid element at pseudocritical temperature located in the buffer layer is discussed.

  17. Effect of Reservoir-Caprock Interface Dip and Circulation of Produced Fluid on CO2-Based Geothermal Heat Extraction from Saline Aquifers

    NASA Astrophysics Data System (ADS)

    Garapati, N.; Randolph, J.; Saar, M. O.

    2014-12-01

    CO2-Plume Geothermal (CPG) energy utilization involves injection of CO2 as a working fluid to extract heat from naturally high permeability geologic units. The injected CO2 forms a large subsurface CO2 plume that absorbs heat from the geothermal reservoir and eventually buoyantly rises to the surface. The CO2 plume can be "tapped" for thermal and/or electric power production in a geothermal power system. In actual systems, the CO2 plume would likely be skewed opposite any likely dip direction of the reservoir-caprock interface. Here, we numerically analyze the characteristics of CO2 plume formation and geothermal heat extraction from geothermal reservoirs with dip. We find that the heat extraction rate and the total amount of heat extracted over time is the same for symmetric and skewed CO2 plume systems when the circular, horizontal production well is arranged according to the CO2 plume distribution around the injection well. We also conduct simulations of CO2 plume formation within a pre-existing groundwater flow field and find that groundwater flow is not capable of skewing the CO2 plume. Furthermore, we investigate the effects of reinjecting small amounts of brine that are produced with the CO2. Brine has a smaller mobility than supercritical CO2 at a given temperature and thus accumulates near the injection well. Such brine accumulation reduces the relative permeability for the CO2 phase, which in turn increases the pore-fluid pressure around the injection well. For this reason, and as injection of two fluid phases is problematic, we recommend removal of any brine from the produced fluid before the cooled CO2 is reinjected into the reservoir. Separated brine may be reinjected into the formation away from the CO2 plume, providing an additional means of controlling and directing the CO2 plume pressure field and flow direction and avoiding the need to treat and dispose of the CO2 near the land surface. In summary, we show that the geothermal heat extraction

  18. Supercritical fluid processing: opportunities for new resist materials and processes

    NASA Astrophysics Data System (ADS)

    Gallagher-Wetmore, Paula M.; Ober, Christopher K.; Gabor, Allen H.; Allen, Robert D.

    1996-05-01

    Over the past two decades supercritical fluids have been utilized as solvents for carrying out separations of materials as diverse as foods, polymers, pharmaceuticals, petrochemicals, natural products, and explosives. More recently they have been used for non-extractive applications such as recrystallization, deposition, impregnation, surface modification, and as a solvent alternative for precision parts cleaning. Today, supercritical fluid extraction is being practiced in the foods and beverage industries; there are commercial plants for decaffeinating coffee and tea, extracting beer flavoring agents from hops, and separating oils and oleoresins from spices. Interest in supercritical fluid processing of polymers has grown over the last ten years, and many new purification, fractionation, and even polymerization techniques have emerged. One of the most significant motivations for applying this technology to polymers has been increased performance demands. More recently, with increasing scrutiny of traditional solvents, supercritical fluids, and in particular carbon dioxide, are receiving widespread attention as 'environmentally conscious' solvents. This paper describes several examples of polymers applications, including a few involving photoresists, which demonstrate that as next- generation advanced polymer systems emerge, supercritical fluids are certain to offer advantages as cutting edge processing tools.

  19. Formation of submicron magnesite during reaction of natural forsterite in H2O-saturated supercritical CO2

    NASA Astrophysics Data System (ADS)

    Qafoku, Odeta; Hu, Jianzhi; Hess, Nancy J.; Hu, Mary Y.; Ilton, Eugene S.; Feng, Ju; Arey, Bruce W.; Felmy, Andrew R.

    2014-06-01

    Natural forsterite was reacted in bulk liquid water saturated with supercritical CO2 (scCO2) and scCO2 saturated with water at 35-80 °C and 90 atm. The solid reaction products were analyzed with nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and confocal Raman spectroscopy. Two carbonate phases, nesquehonite (MgCO3·3H2O) and magnesite (MgCO3), were identified with the proportions of the two phases depending on experimental conditions. In liquid water saturated with scCO2, nesquehonite was the dominant carbonate phase at 35-80 °C with only a limited number of large, micron size magnesite particles forming at the highest temperature, 80 °C. In contrast, in scCO2 saturated with H2O magnesite formation was identified at all three temperatures: 35, 50, and 80 °C. Magnesite was the dominant carbonation reaction product at 50 and 80 °C, but nesquehonite was dominant at 35 °C. The magnesite particles formed under scCO2 saturated with H2O conditions exhibited an extremely uniform submicron grain-size and nearly identical rhombohedral morphologies at all temperatures. The distribution and form of the particles were not consistent with nucleation and growth on the forsterite surface.

  20. Formation of Submicron Magnesite during Reaction of Natural Forsterite in H2O-Saturated Supercritical CO2

    SciTech Connect

    Qafoku, Odeta; Hu, Jian Z.; Hess, Nancy J.; Hu, Mary Y.; Ilton, Eugene S.; Feng, Ju; Arey, Bruce W.; Felmy, Andrew R.

    2014-06-01

    Natural forsterite was reacted in a) liquid water saturated with supercritical CO2 (scCO2) and in b) H2O-saturated scCO2 at 35-80 °C and 90 atm. The solid reaction products were analyzed with nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and confocal Raman spectroscopy. Two carbonate phases, nesquehonite (MgCO3.3H2O) and magnesite (MgCO3), were identified with the proportions of the two phases depending on experimental conditions. In water saturated with scCO2, nesquehonite was the dominant carbonate phase at 35-80 °C with only a limited number of large, micron size magnesite particles forming at the highest temperature, 80 °C. In contrast, in H2O-saturated scCO2 magnesite formation was identified at all three temperatures: 35 °, 50 °, and 80 °C. Magnesite was the dominant carbonation reaction product at 50 ° and 80 °C; but nesquehonite was dominant at 35 °C. The magnesite particles formed under H2O-saturated scCO2 conditions exhibited an extremely uniform submicron grain-size and nearly identical rhombohedral morphologies at all temperatures. The distribution and form of the particles were not consistent with epitaxial nucleation and growth on the forsterite surface.

  1. Fischer-Tropsch synthesis in supercritical fluids. Final report

    SciTech Connect

    Akgerman, A.; Bukur, D.B.

    1998-12-31

    The objective of this study was to investigate Fischer-Tropsch Synthesis (FTS) in the supercritical phase employing a commercial precipitated iron catalysts. As the supercritical fluid the authors used propane and n-hexane. The catalyst had a nominal composition of 100 Fe/5 Cu/4.2 K/25 SiO{sub 2} on mass basis and was used in a fixed bed reactor under both normal (conventional) and supercritical conditions. Experimental data were obtained at different temperatures (235 C, 250 C, and 260 C) and synthesis gas feed compositions (H{sub 2}/CO molar feed ratio of 0.67, 1.0 and 2.0) in both modes of operation under steady state conditions. The authors compared the performance of the precipitated iron catalyst in the supercritical phase, with the data obtained in gas phase (fixed bed reactor) and slurry phase (STS reactor). Comparisons were made in terms of bulk catalyst activity and various aspects of product selectivity (e.g. lumped hydrocarbon distribution and olefin content as a function of carbon number). In order to gain better understanding of the role of intraparticle mass transfer during FTS under conventional or supercritical conditions, the authors have measured diffusivities of representative hydrocarbon products in supercritical fluids, as well as their effective diffusion rates into the pores of catalyst at the reaction conditions. They constructed a Taylor dispersion apparatus to measure diffusion coefficients of hydrocarbon products of FTS in sub and supercritical ethane, propane, and hexane. In addition, they developed a tracer response technique to measure the effective diffusivities in the catalyst pores at the same conditions. Based on these results they have developed an equation for prediction of diffusion in supercritical fluids, which is based on the rough hard sphere theory.

  2. Supercritical CO2 extraction of functional compounds from Spirulina and their biological activity.

    PubMed

    K G, Mallikarjun Gouda; K, Udaya Sankar; R, Sarada; G A, Ravishankar

    2015-06-01

    Supercritical carbon dioxide (SCCO2) extraction and fractionation of Spirulina platensis was carried out to obtain functional compounds with antioxidant, antimicrobial and enzyme inhibitory activities. Extraction of SCCO2 was carried out using 200 g of Spirulina powder at 40 ºC under 120 bar pressure with CO2 flow rate of 1.2 kg h(-1). SCCO2 fraction obtained was further treated with hexane and ethyl acetate to identify its components. Individual components were identified by comparing mass spectra of samples with standard data and retention indices (RI) of C5-C20 n-alkanes mixture using the kovat index formula. The phenolic and flavonoid content of the SCCO2 extract was found to be 0.34 ± 0.01 g/100 g and 0.12 ± 0.01 g/100 g respectively. The SCCO2 extract had antioxidant activity with IC50 value of 109.6 ± 3.0 μg mL(-1) for DPPH (2,2-Diphenyl-1-picryl hydrazyl radical), IC50 value of 81.66 ± 2.5 μg mL(-1) for reducing power and IC50 value of 112.70 ± 0.8 μg mL(-1) for hydroxyl radical scavenging activity. Further, antioxidant activity study on oxidative induced DNA damage was analysed to elucidate the positive role of SCCO2 extract. SCCO2 extracts showed high antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus FRI 722 and Bacillus cereus F 4810) compared to that of Gram negative bacteria (Escherichia coli MTCC 108 and Yersinia enterocolitica MTCC 859). The SCCO2 extract exhibited inhibitory activity on both Angiotensin-1 converting enzyme and α-glucosidase with IC50 values of 274 ± 1.0 μg mL(-1) and 307 ± 2.0 μg mL(-1) respectively. PMID:26028745

  3. Mass transfer enhancement in supercritical fluids extraction by means of power ultrasound.

    PubMed

    Riera, E; Golás, Y; Blanco, A; Gallego, J A; Blasco, M; Mulet, A

    2004-05-01

    The use of high-intensity ultrasound represents an efficient manner of producing small scale agitation, enhancing mass transfer on supercritical fluids (SF) extraction processes. In this way, a supercritical CO(2) extraction of oil from particulate almonds using power ultrasound was studied. To examine the effect of the acoustic waves all experiments were performed with and without ultrasound. A power ultrasonic transducer for a working frequency of about 20 kHz was constructed and installed inside a high-pressure 5 l SF extractor. The experimental tests were carried out with CO(2) at 280 bar and 55 degrees C. Grounded almonds with an oil content of about 55%, in an amount of 1500 g were deposited inside the SF reactor where the solvent was introduced at a flow rate of 20 kg/h. The results show that the kinetics and the extraction yield of the oil were enhanced by 30% and 20% respectively, when a power of about 50 W was applied to the transducer. The average time of each extraction process was of about 8 h and 30 min. In addition, the transducer was also used as a sensitive probe capable to detect the phase behavior of supercritical fluids when it was driven with low power signals. PMID:15081988

  4. Supercritical CO2 interpolymer complex encapsulation improves heat stability of probiotic bifidobacteria.

    PubMed

    Thantsha, M S; Labuschagne, P W; Mamvura, C I

    2014-02-01

    The probiotic industry faces the challenge of retention of probiotic culture viability as numbers of these cells within their products inevitably decrease over time. In order to retain probiotic viability levels above the therapeutic minimum over the duration of the product's shelf life, various methods have been employed, among which encapsulation has received much interest. In line with exploitation of encapsulation for protection of probiotics against adverse conditions, we have previously encapsulated bifidobacteria in poly-(vinylpyrrolidone)-poly-(vinylacetate-co-crotonic acid) (PVP:PVAc-CA) interpolymer complex microparticles under supercritical conditions. The microparticles produced had suitable characteristics for food applications and also protected the bacteria in simulated gastrointestinal fluids. The current study reports on accelerated shelf life studies of PVP:PVAc-CA encapsulated Bifidobacterium lactis Bb12 and Bifidobacterium longum Bb46. Samples were stored as free powders in glass vials at 30 °C for 12 weeks and then analysed for viable counts and water activity levels weekly or fortnightly. Water activities of the samples were within the range of 0.25-0.43, with an average a(w) = 0.34, throughout the storage period. PVP:PVAc-CA interpolymer complex encapsulation retained viable levels above the recommended minimum for 10 and 12 weeks, for B. longum Bb46 and B. lactis Bb12, respectively, thereby extending their shelf lives under high storage temperature by between 4 and 7 weeks. These results reveal the possibility for manufacture of encapsulated probiotic powders with increased stability at ambient temperatures. This would potentially allow the supply of a stable probiotic formulation to impoverished communities without proper storage facilities recommended for most of the currently available commercial probiotic products. PMID:23990069

  5. [Preparation of curcumin-EC sustained-release composite particles by supercritical CO2 anti-solvent technology].

    PubMed

    Bai, Wei-li; Yan, Ting-yuan; Wang, Zhi-xiang; Huang, De-chun; Yan, Ting-xuan; Li, Ping

    2015-01-01

    Curcumin-ethyl-cellulose (EC) sustained-release composite particles were prepared by using supercritical CO2 anti-solvent technology. With drug loading and yield of inclusion complex as evaluation indexes, on the basis of single factor tests, orthogonal experimental design was used to optimize the preparation process of curcumin-EC sustained-release composite particles. The experiments such as drug loading, yield, particle size distribution, electron microscope analysis (SEM) , infrared spectrum (IR), differential scanning calorimetry (DSC) and in vitro dissolution were used to analyze the optimal process combination. The orthogonal experimental optimization process conditions were set as follows: crystallization temperature 45 degrees C, crystallization pressure 10 MPa, curcumin concentration 8 g x L(-1), solvent flow rate 0.9 mL x min(-1), and CO2 velocity 4 L x min(-1). Under the optimal conditions, the average drug loading and yield of curcumin-EC sustained-release composite particles were 33.01% and 83.97%, and the average particle size of the particles was 20.632 μm. IR and DSC analysis showed that curcumin might complex with EC. The experiments of in vitro dissolution showed that curcumin-EC composite particles had good sustained-release effect. Curcumin-EC sustained-release composite particles can be prepared by supercritical CO2 anti-solvent technology. PMID:26080549

  6. Is there a third order phase transition for supercritical fluids?

    PubMed

    Zhu, Jinglong; Zhang, Pingwen; Wang, Han; Site, Luigi Delle

    2014-01-01

    We prove that according to Molecular Dynamics (MD) simulations of liquid mixtures of Lennard-Jones (L-J) particles, there is no third order phase transition in the supercritical regime beyond Andrew's critical point. This result is in open contrast with recent theoretical studies and experiments which instead suggest not only its existence but also its universality regarding the chemical nature of the fluid. We argue that our results are solid enough to go beyond the limitations of MD and the generic character of L-J models, thus suggesting a rather smooth liquid-vapor thermodynamic behavior of fluids in supercritical regime. PMID:24410228

  7. Supercritical fluid extraction of catechins from Cratoxylum prunifolium dyer and subsequent purification by high-speed counter-current chromatography.

    PubMed

    Cao, X L; Tian, Y; Zhang, T Y; Ito, Y

    2000-11-10

    Supercritical fluid extraction of tea catechins including epigallocatechin-3-O-gallate (EGCG) and epicatechin-3-O-gallate (ECG) from Cratoxylum prunifolium Dyer was performed. The optimization of parameters was carried out using an analytical-scale supercritical fluid extraction (SFE) system designed in our laboratory. Then the extraction was scaled up by 100 times using a preparative SFE system under a set of optimized conditions of 40 degrees C, 25 MPa and modified CO2 with 80% ethanol aqueous solution. The combined yield of EGCG and ECG reached about 1 mg per 1 g of tea leaves where the solubility was near 1.4 x 10(-4) mass fraction of CO2 fluid. EGCG and ECG of high purity (>98%) were obtained from the crude preparative extract by high-speed counter-current chromatography. PMID:11185625

  8. Coupling Between Fluid Flow and Heat Transfer - A Mechanism for Quasi-Periodic Variations in CO2 Discharges from Deep Underground Sources

    NASA Astrophysics Data System (ADS)

    Pruess, K.

    2004-12-01

    Leakage of CO2 from underground sources is of interest in connection with volcanic hazards assessment, and with the integrity and safety of geologic disposal reservoirs for CO2 that have been proposed as a means for mitigating global warming from atmospheric emissions. Underground accumulations of CO2, whether naturally occurring or man-made, store vast amounts of compressional energy. At subsurface temperature and pressure conditions, CO2 is always buoyant relative to aqueous fluids, and its upward migration may conceivably give rise to a self-enhancing runaway release due to decompression and the much lower viscosity as compared to water. Natural occurrences of CO2 have been implicated in hydrothermal eruptions, and may be capable of causing "pneumatic" eruptions that are not powered by thermal energy. We have performed numerical simulations of CO2 release through fracture zones and faults in order to determine under what conditions, if any, a self-enhancing, eruptive release may be possible. Our simulations include coupling between multiphase fluid flow and associated heat transfer effects, and accurately represent the thermophysical properties of CO2 in sub-critical (liquid or gaseous) and supercritical conditions, as well as transitions between different phase compositions, and phase partitioning between CO2-rich and aqueous phases. The behavior of rising CO2 plumes is found to be strongly affected by heat transfer effects. As supercritical CO2 migrates upward it cools due to expansion. Much stronger cooling may arise from boiling of liquid CO2 that may occur after temperatures and pressures drop below critical values (Tcrit = 31.04 deg-C, Pcrit = 73.82 bar). Our simulations of CO2 migration up a fault zone produce quasi-periodic cycling of thermodynamic conditions and substantial variations of CO2 fluxes discharged at the land surface on a time scale of order 1 year. This behavior is explained in terms of an interplay between multiphase flow in the fault zone

  9. Supercritical fluid extraction of natural antioxidants from rosemary:  comparison with liquid solvent sonication.

    PubMed

    Tena, M T; Valcárcel, M; Hidalgo, P J; Ubera, J L

    1997-02-01

    Supercritical fluid extraction (SFE) and liquid solvent sonication, in combination with two different sample treatments, were compared for the extraction of natural antioxidants from rosemary leaves. Dried, ground, and sieved rosemary leaves (20 mg) were subjected to SFE with CO(2) at 355 bar at 100 °C (CO(2) density 0.72 g/mL) for 20 min at a liquid flow rate of 4 mL/min. The analytes were concentrated on an ODS trap and subsequently eluted with acetone. Antioxidants in the SF and liquid solvent extract were analyzed by HPLC. Compounds of known antioxidant activity such as carnosol, carnosic acid, and methyl carnosate were identified by mass spectrometry of the HPLC fractions collected. Freezing and grinding the samples in liquid nitrogen resulted in decreased carnosic acid recoveries. Supercritical CO(2) extraction provided the highest recovery of carnosic acid from rosemary leaves (35.7 mg/g), the lowest relative standard deviation (4.4%), and the cleanest extract [Formula: see text] no cleanup prior to HPLC was required. Among the liquid solvents studies, only acetone provided comparable results (73% recovery relative to SC-CO(2) extraction); however, it required decoloration with active carbon prior to HPLC analysis. PMID:21639201

  10. Dynamics of pulsed laser ablation in high-density carbon dioxide including supercritical fluid state

    NASA Astrophysics Data System (ADS)

    Urabe, Keiichiro; Kato, Toru; Stauss, Sven; Himeno, Shohei; Kato, Satoshi; Muneoka, Hitoshi; Baba, Motoyoshi; Suemoto, Tohru; Terashima, Kazuo

    2013-10-01

    To gain a better understanding of pulsed laser ablation (PLA) processes in high-density fluids, including gases, liquids, and supercritical fluids (SCFs), we have investigated the PLA dynamics in high-density carbon dioxide (CO2) using a time-resolved shadowgraph (SG) observation method. The SG images revealed that the PLA dynamics can be categorized into two domains that are separated by the gas-liquid coexistence curve and the Widom line, which forms a border between the gaslike and liquidlike domains of an SCF. Furthermore, a cavitation bubble observed in liquid CO2 near the critical point exhibited a particular characteristic: the formation of an inner bubble and an outer shell structure. The results indicate that the thermophysical properties of the reaction field generated by PLA can be dynamically tuned by controlling the solvent temperature and pressure, particularly near the critical point.

  11. Laboratory Mid-frequency (Kilohertz) Range Seismic Property Measurements and X-ray CT Imaging of Fractured Sandstone Cores During Supercritical CO2 Injection

    NASA Astrophysics Data System (ADS)

    Nakagawa, S.; Kneafsey, T. J.; Chang, C.; Harper, E.

    2014-12-01

    During geological sequestration of CO2, fractures are expected to play a critical role in controlling the migration of the injected fluid in reservoir rock. To detect the invasion of supercritical (sc-) CO2 and to determine its saturation, velocity and attenuation of seismic waves can be monitored. When both fractures and matrix porosity connected to the fractures are present, wave-induced dynamic poroelastic interactions between these two different types of rock porosity—high-permeability, high-compliance fractures and low-permeability, low-compliance matrix porosity—result in complex velocity and attenuation changes of compressional waves as scCO2 invades the rock. We conducted core-scale laboratory scCO2 injection experiments on small (diameter 1.5 inches, length 3.5-4 inches), medium-porosity/permeability (porosity 15%, matrix permeability 35 md) sandstone cores. During the injection, the compressional and shear (torsion) wave velocities and attenuations of the entire core were determined using our Split Hopkinson Resonant Bar (short-core resonant bar) technique in the frequency range of 1-2 kHz, and the distribution and saturation of the scCO2 determined via X-ray CT imaging using a medical CT scanner. A series of tests were conducted on (1) intact rock cores, (2) a core containing a mated, core-parallel fracture, (3) a core containing a sheared core-parallel fracture, and (4) a core containing a sheared, core-normal fracture. For intact cores and a core containing a mated sheared fracture, injections of scCO2 into an initially water-saturated sample resulted in large and continuous decreases in the compressional velocity as well as temporary increases in the attenuation. For a sheared core-parallel fracture, large attenuation was also observed, but almost no changes in the velocity occurred. In contrast, a sample containing a core-normal fracture exhibited complex behavior of compressional wave attenuation: the attenuation peaked as the leading edge of

  12. Extraction of metals using supercritical fluid and chelate forming legand

    DOEpatents

    Wai, Chien M.; Laintz, Kenneth E.

    1998-01-01

    A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated .beta.-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated .beta.-diketone and a trialkyl phosphate, or a fluorinated .beta.-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated .beta.-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.

  13. Extraction of metals using supercritical fluid and chelate forming ligand

    DOEpatents

    Wai, C.M.; Laintz, K.E.

    1998-03-24

    A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated {beta}-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated {beta}-diketone and a trialkyl phosphate, or a fluorinated {beta}-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated {beta}-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process. 7 figs.

  14. Topics in Chemical Instrumentation--An Introduction to Supercritical Fluid Chromatography: Part 1: Principles and Instrumentation.

    ERIC Educational Resources Information Center

    Palmieri, Margo D.

    1988-01-01

    Identifies the properties and characteristics of supercritical fluids. Discusses the methodology for supercritical fluid chromatography including flow rate, plate height, column efficiency, viscosity, and other factors. Reviews instruments, column types, and elution conditions. Lists supercritical fluid data for 22 compounds, mostly organic. (MVL)

  15. Comparative Reactivity Study of Forsterite and Antigorite in Wet Supercritical CO2 by In Situ Infrared Spectroscopy

    SciTech Connect

    Thompson, Christopher J.; Loring, John S.; Rosso, Kevin M.; Wang, Zheming

    2013-10-01

    The carbonation reactions of forsterite (Mg2SiO4) and antigorite [Mg3Si2O5(OH)4], representatives of olivine and serpentine minerals, in dry and wet supercritical carbon dioxide (scCO2) at conditions relevant to geologic carbon sequestration (35 °C and 100 bar) were studied by in-situ Fourier transform infrared (FT-IR) spectroscopy. Our results confirm that water plays a critical role in the reactions between metal silicate minerals and scCO2. For neat scCO2, no reaction was observed in 24 hr for either mineral. When water was added to the scCO2, a thin water film formed on the minerals’ surfaces, and the reaction rates and extents increased as the water saturation level was raised from 54% to 116% (excess water). For the first time, the presence of bicarbonate, a key reaction intermediate for metal silicate reactions with scCO2, was observed in a heterogeneous system where mineral solids, an adsorbed water film, and bulk scCO2 co-exist. In excess-water experiments, approximately 4% of forsterite and less than 2% of antigorite transformed into hydrated Mg-carbonates. A precipitate similar to nesquehonite (MgCO3•3H2O) was observed for forsterite within 6 hr of reaction time, but no such precipitate was formed from antigorite until after water was removed from the scCO2 following a 24-hr reaction period. The reduced reactivity and carbonate-precipitation behavior of antigorite was attributed to slower, incongruent dissolution of the mineral and lower concentrations of Mg2+ and HCO3- in the water film. The in situ measurements employed in this work make it possible to quantify metal carbonate precipitates and key reaction intermediates such as bicarbonate for the investigation of carbonation reaction mechanisms relevant to geologic carbon sequestration.

  16. Efficient separation of curcumin, demethoxycurcumin, and bisdemethoxycurcumin from turmeric using supercritical fluid chromatography: From analytical to preparative scale.

    PubMed

    Song, Wei; Qiao, Xue; Liang, Wen-fei; Ji, Shuai; Yang, Lu; Wang, Yuan; Xu, Yong-wei; Yang, Ying; Guo, De-an; Ye, Min

    2015-10-01

    Curcumin is the major constituent of turmeric (Curcuma longa L.). It has attracted widespread attention for its anticancer and anti-inflammatory activities. The separation of curcumin and its two close analogs, demethoxycurcumin and bisdemethoxycurcumin, has been challenging by conventional techniques. In this study, an environmentally friendly method based on supercritical fluid chromatography was established for the rapid and facile separation of the three curcuminoids directly from the methanol extract of turmeric. The method was first developed and optimized by ultra performance convergence chromatography, and was then scaled up to preparative supercritical fluid chromatography. Eluted with supercritical fluid CO2 containing 8-15% methanol (containing 10 mM oxalic acid) at a flow rate of 80 mL/min, curcumin, demethoxycurcumin and bisdemethoxycurcumin could be well separated on a Viridis BEH OBD column (Waters, 250 mm × 19 mm, 5 μm) within 6.5 min. As a result, 20.8 mg of curcumin (97.9% purity), 7.0 mg of demethoxycurcumin (91.1%), and 4.6 mg of bisdemethoxycurcumin (94.8%) were obtained after a single step of supercritical fluid chromatography separation with a mean recovery of 76.6%. Showing obvious advantages in low solvent consumption, large sample loading, and easy solvent removal, supercritical fluid chromatography was proved to be a superior technique for the efficient separation of natural products. PMID:26256681

  17. Enhanced Geothermal Systems (EGS) comparing water with CO2 as heattransmission fluids

    SciTech Connect

    Pruess, Karsten

    2007-11-01

    This paper summarizes our research to date into operatingEGS with CO2. Our modeling studies indicate that CO2 would achieve morefavorable heat extraction than aqueous fluids. The peculiarthermophysicalproperties of CO2 give rise to unusual features in the dependence ofenergy recovery on thermodynamic conditions and time. Preliminarygeochemical studies suggest that CO2 may avoid unfavorable rock-fluidinteractions that have been encountered in water-basedsystems. To morefully evaluate the potential of EGS with CO2 will require an integratedresearch programme of model development, and laboratory and fieldstudies.

  18. Optimization of conditions for supercritical fluid extraction of flavonoids from hops (Humulus lupulus L.).

    PubMed

    He, Guo-Qing; Xiong, Hao-Ping; Chen, Qi-He; Ruan, Hui; Wang, Zhao-Yue; Traoré, Lonseny

    2005-10-01

    Waste hops are good sources of flavonoids. Extraction of flavonoids from waste hops (SC-CO(2) extracted hops) using supercritical fluids technology was investigated. Various temperatures, pressures and concentrations of ethanol (modifier) and the ratio (w/w) of solvent to material were tested in this study. The results of single factor and orthogonal experiments showed that at 50 degrees C, 25 MPa, the ratio of solvent to material (50%), ethanol concentration (80%) resulted in maximum extraction yield flavonoids (7.8 mg/g). HPLC-MS analysis of the extracts indicated that flavonoids obtained were xanthohumol, the principal prenylflavonoid in hops. PMID:16187413

  19. Basalt Reactivity Variability with Reservoir Depth in Supercritical CO2 and Aqueous Phases

    SciTech Connect

    Schaef, Herbert T.; McGrail, B. Peter; Owen, Antionette T.

    2011-04-01

    Long term storage of CO{sub 2} in geologic formations is currently considered the most attractive option to reduce greenhouse gas emissions while continuing to utilize fossil fuels for energy production. Injected CO{sub 2} is expected to reside as a buoyant water-saturated supercritical fluid in contact with reservoir rock, the caprock system, and related formation waters. As was reported for the first time at the GHGT-9 conference, experiments with basalts demonstrated surprisingly rapid carbonate mineral formation occurring with samples suspended in the scCO{sub 2} phase. Those experiments were limited to a few temperatures and CO{sub 2} pressures representing relatively shallow (1 km) reservoir depths. Because continental flood basalts can extend to depths of 5 km or more, in this paper we extend the earlier results across a pressure-temperature range representative of these greater depths. Different basalt samples, including well cuttings from the borehole used in a pilot-scale basalt sequestration project (Eastern Washington, U.S.) and core samples from the Central Atlantic Magmatic Province (CAMP), were exposed to aqueous solutions in equilibrium with scCO{sub 2} and water-rich scCO{sub 2} at six different pressures and temperatures for select periods of time (30 to 180 days). Conditions corresponding to a shallow injection of CO{sub 2} (7.4 MPa, 34 C) indicate limited reactivity with basalt; surface carbonate precipitates were not easily identified on post-reacted basalt grains. Basalts exposed under identical times appeared increasingly more reacted with simulated depths. Tests, conducted at higher pressures (12.0 MPa) and temperatures (55 C), reveal a wide variety of surface precipitates forming in both fluid phases. Under shallow conditions tiny clusters of aragonite needles began forming in the wet scCO{sub 2} fluid, whereas in the CO{sub 2} saturated water, cation substituted calcite developed thin radiating coatings. Although these types of coatings

  20. Investigation of Wyoming Bentonite Hydration in Dry to Water-Saturated Supercritical CO2: Implications for Caprock Integrity

    NASA Astrophysics Data System (ADS)

    Loring, J. S.; Chen, J.; Thompson, C.; Schaef, T.; Miller, Q. R.; Martin, P. F.; Ilton, E. S.; Qafoku, O.; Felmy, A. R.; Rosso, K. M.

    2012-12-01

    The effectiveness of geologic sequestration as an enterprise for CO2 storage depends partly on the reactivity of supercritical CO2 (scCO2) with caprock minerals. Injection of scCO2 will displace formation water, and the pore space adjacent to overlying caprocks could eventually be dominated by dry to water-saturated scCO2. Caprock formations have high concentrations of clay minerals, including expandable montmorillonites. Water-bearing scCO2 is highly reactive and capable of hydrating or dehydrating clays, possibly leading to porosity and permeability changes that directly impact caprock performance. Dehydration will cause montmorillonite clay minerals in caprocks to contract, thereby decreasing solid volume and possibly increasing caprock permeability and porosity. On the other hand, water intercalation will cause these clays to expand, thereby increasing solid volume and possibly leading to self-sealing of caprock fractures. Pacific Northwest National Laboratory's Carbon Sequestration Initiative is developing capabilities for studying wet scCO2-mineral reactions in situ. Here, we introduce novel in situ infrared (IR) spectroscopic instrumentation that enables quantitative titrations of reactant minerals with water in scCO2. Results are presented for the infrared spectroscopic titrations of Na-, Ca-, and Mg-saturated Wyoming betonites with water over concentrations ranging from zero to scCO2 saturated. These experiments were carried out at 50°C and 90 bar. Transmission IR spectroscopy was used to measure concentrations of water dissolved in the scCO2 or intercalated into the clays. The titration curves evaluated from the transmission-IR data are compared between the three types of clays to assess the effects of the cation on water partitioning. Single-reflection attenuated total reflection (ATR) IR spectroscopy was used to collect the spectrum of the clays as they hydrate at every total water concentration during the titration. Clay hydration is evidenced by

  1. Experimental and simulation studies of pore scale flow and reactive transport associated with supercritical CO2 injection into brine-filled reservoir rocks (Invited)

    NASA Astrophysics Data System (ADS)

    DePaolo, D. J.; Steefel, C. I.; Bourg, I. C.

    2013-12-01

    This talk will review recent research relating to pore scale reactive transport effects done in the context of the Department of Energy-sponsored Energy Frontier Research Center led by Lawrence Berkeley National Laboratory with several other laboratory and University partners. This Center, called the Center for Nanoscale Controls on Geologic CO2 (NCGC) has focused effort on the behavior of supercritical CO2 being injected into and/or residing as capillary trapped-bubbles in sandstone and shale, with particular emphasis on the description of nanoscale to pore scale processes that could provide the basis for advanced simulations. In general, simulation of reservoir-scale behavior of CO2 sequestration assumes a number of mostly qualitative relationships that are defensible as nominal first-order descriptions of single-fluid systems, but neglect the many complications that are associated with a two-phase or three-phase reactive system. The contrasts in properties, and the mixing behavior of scCO2 and brine provide unusual conditions for water-rock interaction, and the NCGC has investigated the underlying issues by a combination of approaches including theoretical and experimental studies of mineral nucleation and growth, experimental studies of brine films, mineral wetting properties, dissolution-precipitation rates and infiltration patterns, molecular dynamic simulations and neutron scattering experiments of fluid properties for fluid confined in nanopores, and various approaches to numerical simulation of reactive transport processes. The work to date has placed new constraints on the thickness of brine films, and also on the wetting properties of CO2 versus brine, a property that varies between minerals and with salinity, and may also change with time as a result of the reactivity of CO2-saturated brine. Mineral dissolution is dependent on reactive surface area, which can be shown to vary by a large factor for various minerals, especially when correlated with

  2. Design at the nanometre scale of multifunctional materials using supercritical fluid chemical deposition

    NASA Astrophysics Data System (ADS)

    Marre, Samuel; Cansell, François; Aymonier, Cyril

    2006-09-01

    Recent developments in multifunctional devices show the interest in combining different materials to obtain specific properties. Through supercritical fluid chemical deposition (SFCD), silica spheres, used as a model support, were coated with copper nanoparticles (5-17 nm) with a tuneable amount of coverage (40-80%). The coating process is based on the reduction of metal precursors with hydrogen in a supercritical CO2/isopropanol mixture in a temperature range between 100 and 150 °C at 24 MPa. Several parameters were studied such as temperature, residence time or mass ratio of precursor/silica spheres, allowing control of the size of the copper nanoparticles and of the amount of coverage from metal nanoparticles scattered onto the surface to a metal nanoparticle thin film.

  3. Disintegration of fluids under supercritical conditions from mixing layer studies

    NASA Technical Reports Server (NTRS)

    Okong'o, N.; Bellan, J.

    2003-01-01

    Databases of transitional states obtained from Direct Numerical simulations (DNS) of temporal, supercritical mixing layers for two species systems, O2/H2 and C7H16/N2, are analyzed to elucidate species-specific turbulence aspects and features of fluid disintegration.

  4. Supercritical fluid extraction in plant essential and volatile oil analysis.

    PubMed

    Pourmortazavi, Seied Mahdi; Hajimirsadeghi, Seiedeh Somayyeh

    2007-09-01

    The use of supercritical fluids, especially carbon dioxide, in the extraction of plant volatile components has increased during two last decades due to the expected advantages of the supercritical extraction process. Supercritical fluid extraction (SFE) is a rapid, selective and convenient method for sample preparation prior to the analysis of compounds in the volatile product of plant matrices. Also, SFE is a simple, inexpensive, fast, effective and virtually solvent-free sample pretreatment technique. This review provides a detailed and updated discussion of the developments, modes and applications of SFE in the isolation of essential oils from plant matrices. SFE is usually performed with pure or modified carbon dioxide, which facilitates off-line collection of extracts and on-line coupling with other analytical methods such as gas, liquid and supercritical fluid chromatography. In this review, we showed that a number of factors influence extraction yields, these being solubility of the solute in the fluid, diffusion through the matrix and collection process. Finally, SFE has been compared with conventional extraction methods in terms of selectivity, rapidity, cleanliness and possibility of manipulating the composition of the extract. PMID:17624357

  5. Method for nucleic acid isolation using supercritical fluids

    DOEpatents

    Nivens, D.E.; Applegate, B.M.

    1999-07-13

    A method is disclosed for detecting the presence of a microorganism in an environmental sample involves contacting the sample with a supercritical fluid to isolate nucleic acid from the microorganism, then detecting the presence of a particular sequence within the isolated nucleic acid. The nucleic acid may optionally be subjected to further purification. 4 figs.

  6. Method for nucleic acid isolation using supercritical fluids

    DOEpatents

    Nivens, David E.; Applegate, Bruce M.

    1999-01-01

    A method for detecting the presence of a microorganism in an environmental sample involves contacting the sample with a supercritical fluid to isolate nucleic acid from the microorganism, then detecting the presence of a particular sequence within the isolated nucleic acid. The nucleic acid may optionally be subjected to further purification.

  7. Using ground and intact coal Samples to evaluate hydrocarbon fate during supercritical CO2 injection into coal beds: effects of particle size and coal moisture

    USGS Publications Warehouse

    Kolak, Jon; Hackley, Paul C.; Ruppert, Leslie F.; Warwick, Peter D.; Burruss, Robert

    2015-01-01

    To investigate the potential for mobilizing organic compounds from coal beds during geologic carbon dioxide (CO2) storage (sequestration), a series of solvent extractions using dichloromethane (DCM) and using supercritical CO2 (40 °C and 10 MPa) were conducted on a set of coal samples collected from Louisiana and Ohio. The coal samples studied range in rank from lignite A to high volatile A bituminous, and were characterized using proximate, ultimate, organic petrography, and sorption isotherm analyses. Sorption isotherm analyses of gaseous CO2 and methane show a general increase in gas storage capacity with coal rank, consistent with findings from previous studies. In the solvent extractions, both dry, ground coal samples and moist, intact core plug samples were used to evaluate effects of variations in particle size and moisture content. Samples were spiked with perdeuterated surrogate compounds prior to extraction, and extracts were analyzed via gas chromatography–mass spectrometry. The DCM extracts generally contained the highest concentrations of organic compounds, indicating the existence of additional hydrocarbons within the coal matrix that were not mobilized during supercritical CO2 extractions. Concentrations of aliphatic and aromatic compounds measured in supercritical CO2 extracts of core plug samples generally are lower than concentrations in corresponding extracts of dry, ground coal samples, due to differences in particle size and moisture content. Changes in the amount of extracted compounds and in surrogate recovery measured during consecutive supercritical CO2extractions of core plug samples appear to reflect the transition from a water-wet to a CO2-wet system. Changes in coal core plug mass during supercritical CO2 extraction range from 3.4% to 14%, indicating that a substantial portion of coal moisture is retained in the low-rank coal samples. Moisture retention within core plug samples, especially in low-rank coals, appears to inhibit

  8. Reverse micelle and microemulsion phases in supercritical fluids

    SciTech Connect

    Fulton, J.L.; Smith, R.D.

    1988-05-19

    The surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) was used to form reverse micelle and microemulsion phases in supercritical ethane and propane for systems consisting of 80-100% alkane by weight. Phase diagrams obtained from view cell studies of microemulsion phases formed in supercritical fluids are reported and shown to be strongly dependent on pressure. The properties of these solutions were also characterized by conductivity, density, and surfactant solubility measurements. The solubility of AOT in ethane and propane over a range of pressures shows behavior typical of solids in supercritical fluids. The maximum water-to-surfactant ratio (W/sub 0/) increased dramatically in both ethane and propane systems as pressure was increased. At 300 bar and 103/sup 0/C, the supercritical propane-surfactant system is capable of solubilizing much more water (W/sub 0/ = 12) than the supercritical ethane-surfactant system (W/sub 0/ = 4) at 300 bar and 37/sup 0/C. Some of the important thermodynamic contributions that are likely responsible for this pressure-dependent phase behavior are discussed, and potential applications of this new class of solvents are considered.

  9. Clean synthesis of molecular recognition polymeric materials with chiral sensing capability using supercritical fluid technology. Application as HPLC stationary phases.

    PubMed

    da Silva, Mara Soares; Vão, Eva R; Temtem, Márcio; Mafra, Luís; Caldeira, Jorge; Aguiar-Ricardo, Ana; Casimiro, Teresa

    2010-03-15

    Molecularly imprinted polymers (MIPs) of poly(ethylene glycol dimethacrylate) and poly(N-isopropylacrylamide-co-ethylene glycol dimethacrylate) were synthesized for the first time in supercritical carbon dioxide (scCO(2)), using Boc-L-tryptophan as template. Supercritical fluid technology provides a clean and one-step synthetic route for the preparation of affinity polymeric materials with sensing capability for specific molecules. The polymeric materials were tested as stationary HPLC phases for the enantiomeric separation of L- and D-tryptophan. HPLC results prove that the synthesized MIPs are able to recognize the template molecule towards its enantiomer which opens up potential applications in chromatographic chiral separation. PMID:20096557

  10. Supercritical CO2 Migration under Cross-Bedded Structures: Outcrop Analog from the Jurassic Navajo Sandstone

    NASA Astrophysics Data System (ADS)

    Lee, S.; Allen, J.; Han, W.; Lu, C.; McPherson, B. J.

    2011-12-01

    Jurassic aeolian sandstones (e.g. Navajo and White Rim Sandstones) on the Colorado Plateau of Utah have been considered potential sinks for geologic CO2 sequestration due to their regional lateral continuity, thickness, high porosity and permeability, presence of seal strata and proximity to large point sources of anthropogenic CO2. However, aeolian deposits usually exhibit inherent internal complexities induced by migrating bedforms of different sizes and their resulting bounding surfaces. Therefore, CO2 plume migration in such complex media should be well defined and successively linked in models for better characterization of the plume behavior. Based on an outcrop analog of the upper Navajo Sandstone in the western flank of the San Rafael Swell, Utah, we identified five different bedform types with dune and interdune facies to represent the spatial continuity of lithofacies units. Using generated 3D geometrical facies patterns of cross-bedded structures in the Navajo Sandstone, we performed numerical simulations to understand the detailed behavior of CO2 plume migration under the different cross-bedded bedforms. Our numerical simulation results indicate that cross-bedded structures (bedform types) play an important role on governing the rate and directionality of CO2 migration, resulting in changes of imbibition processes of CO2. CO2 migration tends to follow wind ripple laminations and reactivation surfaces updip. Our results suggest that geologically-based upscaling of CO2 migration is crucial in cross-bedded formations as part of reservoir or basin scale models. Furthermore, comparative modeling studies between 3D models and 2D cross-sections extracted from 3D models showed the significant three-dimensional interplay in a cross-bedded structure and the need to correctly capture the geologic heterogeneity to predict realistic CO2 plume behavior. Our outcrop analog approach presented in this study also demonstrates an alternative method for assessing geologic

  11. Supercritical fluid-mediated methods to encapsulate drugs: recent advances and new opportunities.

    PubMed

    Naylor, Andrew; Lewis, Andrew L; Ilium, Lisbeth

    2011-12-01

    With the advent of the development of novel pharmaceutical products and therapies, there is a need for effective delivery of these products to patients. Dependent on whether they are small-molecular weight drugs or biologics, many new compounds may suffer from poor solubility, poor stability or require frequent administration and therefore require optimized delivery. For example, the utilization of polymorphism and the enhanced solubility in the amorphous state is being exploited to improve the dissolution of small-molecular weight poorly soluble drugs. This can be achieved by the formation of solid dispersions in water-soluble matrices. In addition, encapsulation in biodegradable polymeric materials is one potential route to reduce the frequency of administration through the formation of sustained-release formulations. This is desirable for biologics, for example, which generally require administration once or twice daily. Supercritical fluid processing can achieve both of these outcomes, and this review focuses on the use of supercritical CO2 to encapsulate active pharmaceutical ingredients to enhance solubility or achieve sustained release. Using supercritical CO2-mediated processes provides a clean and potentially solvent-free route to prepare novel drug products and is therefore an attractive alternative to conventional manufacturing technologies. PMID:22833981

  12. Green process for green materials: viable low-temperature lipase-catalysed synthesis of renewable telechelics in supercritical CO2.

    PubMed

    Curia, S; Barclay, A F; Torron, S; Johansson, M; Howdle, S M

    2015-12-28

    We present a novel near-ambient-temperature approach to telechelic renewable polyesters by exploiting the unique properties of supercritical CO(2) (scCO(2)). Bio-based commercially available monomers have been polymerized and functional telechelic materials with targeted molecular weight prepared by end-capping the chains with molecules containing reactive moieties in a one-pot reaction. The use of scCO(2) as a reaction medium facilitates the effective use of Candida antarctica Lipase B (CaLB) as a catalyst at a temperature as low as 35°C, hence avoiding side reactions, maintaining the end-capper functionality and preserving the enzyme activity. The functionalized polymer products have been characterized by (1)H nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry, gel permeation chromatography and differential scanning calorimetry in order to carefully assess their structural and thermal properties. We demonstrate that telechelic materials can be produced enzymatically at mild temperatures, in a solvent-free system and using renewably sourced monomers without pre-modification, by exploiting the unique properties of scCO(2). The macromolecules we prepare are ideal green precursors that can be further reacted to prepare useful bio-derived films and coatings. PMID:26574529

  13. Uranium extraction from TRISO-coated fuel particles using supercritical CO2 containing tri-n-butyl phosphate.

    PubMed

    Zhu, Liyang; Duan, Wuhua; Xu, Jingming; Zhu, Yongjun

    2012-11-30

    High-temperature gas-cooled reactors (HTGRs) are advanced nuclear systems that will receive heavy use in the future. It is important to develop spent nuclear fuel reprocessing technologies for HTGR. A new method for recovering uranium from tristructural-isotropic (TRISO-) coated fuel particles with supercritical CO(2) containing tri-n-butyl phosphate (TBP) as a complexing agent was investigated. TRISO-coated fuel particles from HTGR fuel elements were first crushed to expose UO(2) pellet fuel kernels. The crushed TRISO-coated fuel particles were then treated under O(2) stream at 750°C, resulting in a mixture of U(3)O(8) powder and SiC shells. The conversion of U(3)O(8) into solid uranyl nitrate by its reaction with liquid N(2)O(4) in the presence of a small amount of water was carried out. Complete conversion was achieved after 60 min of reaction at 80°C, whereas the SiC shells were not converted by N(2)O(4). Uranyl nitrate in the converted mixture was extracted with supercritical CO(2) containing TBP. The cumulative extraction efficiency was above 98% after 20 min of online extraction at 50°C and 25 MPa, whereas the SiC shells were not extracted by TBP. The results suggest an attractive strategy for reprocessing spent nuclear fuel from HTGR to minimize the generation of secondary radioactive waste. PMID:23089063

  14. Supercritical CO2/brine transport in a fractured rock under geologic sequestration conditions

    NASA Astrophysics Data System (ADS)

    Kim, Kue-Young; Oh, Junho; Han, Weon Shik

    2013-04-01

    Carbon capture and storage (CCS) is a promising technology for mitigating CO2 emissions into the atmosphere. In general, densely fractured natural reservoirs are rarely considered as suitable candidates due to issues related to safe and secure long-term storage. Nevertheless, assessment of CO2 storage processes in a storage medium with fractures is critical, as fractures occur in nearly all geological settings and play a major role in hydrocarbon migration as well as entrapment. We evaluated the impact of fractures on CO2/brine transport under geologic sequestration conditions by conducting both experimental and numerical studies. Laboratory experimental results showed a piston-like brine displacement with gravity over-run effects in the homogeneous core regardless of CO2 injection rates. In the fractured core, however, two distinctive types of brine displacements were observed; one showing brine displacement only in the fracture whereas the other shows brine displacement both in the fracture and matrix with different rates, depending on the magnitude of the pressure build-up in the matrix. In the experiments, the injectivity in the fractured core was twice greater than that in the homogeneous core at our experimental condition, while the estimated storage capacity was greater in the homogeneous core than in the fractured core by over 1.5 times. Capillary pressure curves were illustrated for both cores including entry pressures and irreducible brine saturation. The free-phase CO2 transfer in a fracture-matrix system was addressed by numerical simulation, and provided transient flux exchange processes during the brine displacement by CO2. The pressure gradient between the fracture and matrix induced CO2 transfer from fracture into matrix at the front of CO2 plume in fracture. In contrast, at the rear zone of CO2 plume, the reversal of pressure gradient resulted in a reverse CO2 flux. Additionally, the influence of fracture aperture on CO2 transfer between fracture

  15. The Effect of Supercritical Fluids on Solid Acid Catalyst Alkylation

    SciTech Connect

    Ginosar, Daniel Michael; Thompson, David Neil; Burch, Kyle Coates; Zalewski, D. J.

    2002-05-01

    The alkylation of isobutane with trans-2-butene was explored over six solid acid catalysts in the liquid, near-critical liquid, and supercritical regions through the addition of an inert cosolvent to the reaction feed mixture. The addition of supercritical cosolvents did not result in sustained catalytic alkylation activity. A modest improvement in product yield was obtained with the addition of methane in the modified-liquid region; however, catalyst longevity and product selectivity were decreased compared to cosolvent-free liquid conditions. This paper describes the catalyst screening and selection process, an exploration of catalyst performance with varying concentrations of methane, and an examination of the effects of seven supercritical fluids on catalyst performance. The catalysts included two zeolites, two sulfated metal oxides, and two Nafion catalysts. Three hydrocarbons, two fluorocarbons, carbon dioxide, and sulfur hexafluoride were explored as inert cosolvents added to the reaction mixture.

  16. Solvation effects on reactions of triplet benzophenone in supercritical fluids

    SciTech Connect

    Roberts, C.B.; Brennecke, J.F.; Chateauneuf, J.E.

    1995-05-01

    Laser flash photolysis of the hydrogen abstraction reaction of triplet benzophenone ({sup 3}BP) from 2-propanol and 1,4-cyclohexadiene in supercritical ethane and fluoroform was investigated. Bimolecular rate constants based on bulk concentrations decrease with an increase in pressure along both isotherms studied. These results corroborate previous studies in CO{sub 2} that show increased reaction rates due to enhanced local compositions of cosolvent around the {sup 3}BP solute. Analysis of the results includes prediction of the thermodynamic pressure effect on the rate constant, which suggests an increase in the rate constant with pressure, as well as the effects of increased local cosolvent concentrations about {sup 3}BP. Spectroscopic measurements of the local composition of 2-propanol about a solute in supercritical CO{sub 2} are used to explain the apparent discrepancy between experiment and prediction, providing reasonable evidence that the local environment can influence kinetically controlled reactions in supercritical fluids.

  17. The use of solvent extractions and solubility theory to discern hydrocarbon associations in coal, with application to the coal-supercritical CO2 system

    USGS Publications Warehouse

    Kolak, Jonathan J.; Burruss, Robert A.

    2014-01-01

    Samples of three high volatile bituminous coals were subjected to parallel sets of extractions involving solvents dichloromethane (DCM), carbon disulfide (CS2), and supercritical carbon dioxide (CO2) (40 °C, 100 bar) to study processes affecting coal–solvent interactions. Recoveries of perdeuterated surrogate compounds, n-hexadecane-d34 and four polycyclic aromatic hydrocarbons (PAHs), added as a spike prior to extraction, provided further insight into these processes. Soxhlet-DCM and Soxhlet-CS2 extractions yielded similar amounts of extractable organic matter (EOM) and distributions of individual hydrocarbons. Supercritical CO2 extractions (40 °C, 100 bar) yielded approximately an order of magnitude less EOM. Hydrocarbon distributions in supercritical CO2 extracts generally mimicked distributions from the other solvent extracts, albeit at lower concentrations. This disparity increased with increasing molecular weight of target hydrocarbons. Five- and six-ring ring PAHs generally were not detected and no asphaltenes were recovered in supercritical CO2 extractions conducted at 40 °C and 100 bar. Supercritical CO2 extraction at elevated temperature (115 °C) enhanced recovery of four-ring and five-ring PAHs, dibenzothiophene (DBT), and perdeuterated PAH surrogate compounds. These results are only partially explained through comparison with previous measurements of hydrocarbon solubility in supercritical CO2. Similarly, an evaluation of extraction results in conjunction with solubility theory (Hildebrand and Hansen solubility parameters) does not fully account for the hydrocarbon distributions observed among the solvent extracts. Coal composition (maceral content) did not appear to affect surrogate recovery during CS2 and DCM extractions but might affect supercritical CO2 extractions, which revealed substantive uptake (partitioning) of PAH surrogates into the coal samples. This uptake was greatest in the sample (IN-1) with the highest vitrinite content. These

  18. Antimutagenicity of supercritical CO2 extracts of Terminalia catappa leaves and cytotoxicity of the extracts to human hepatoma cells.

    PubMed

    Ko, Ting-Fu; Weng, Yih-Ming; Lin, Shwu-Bin; Chiou, Robin Y-Y

    2003-06-01

    Natural antimutagens may prevent cancer and are therefore of great interest to oncologists and the public at large. Phytochemicals are potent antimutagen candidates. When the Ames test was applied to examine the antimutagenic potency of supercritical carbon dioxide (SC-CO(2)) extracts of Terminalia catappa leaves at a dose of 0.5 mg/plate, toxicity and mutagenicity were not detected. The antimutagenic activity of SC-CO(2) extracts increased with decreases of temperature (60, 50, and 40 degrees C) and pressure (4000, 3000, and 2000 psi) used for extraction. The most potent antimutagenicity was observed in extracts obtained at 40 degrees C and 2000 psi. At a dose of 0.5 mg of extract/plate, approximately 80% of the mutagenicity of benzo[a]pyrene (B[a]P, with S-9) and 46% of the mutagenicity of N-methyl-N '-nitroguanidine (MNNG, without S-9) were inhibited. Media supplemented with SC-CO(2) extracts at a range of 0-500 microg/mL were used to cultivate human hepatoma (Huh 7) and normal liver (Chang liver) cells. The viability of the cells was assayed by measuring cellular acid phosphatase activity. A dose-dependent growth inhibition of both types of cells was observed. The SC-CO(2) extracts were more cytotoxic to Huh 7 cells than to Chang liver cells. The observation that SC-CO(2) extracts of T. catappa leaves did not induce mutagenicity at the doses tested while exhibiting potent antimutagenicity and were more cytotoxic to human hepatoma cells than to normal liver cells is of merit and warrants further investigation. PMID:12769525

  19. Experimental analysis of spatial correlation effects on capillary trapping of supercritical CO2 at the intermediate laboratory scale in heterogeneous porous media

    NASA Astrophysics Data System (ADS)

    Trevisan, Luca; Pini, Ronny; Cihan, Abdullah; Birkholzer, Jens T.; Zhou, Quanlin; Illangasekare, Tissa H.

    2015-11-01

    Several numerical studies have demonstrated that the heterogeneous nature of typical sedimentary formations can favorably dampen the accumulation of mobile CO2 phase underneath the caprock. Core flooding experiments have also shown that contrasts in capillary entry pressure can lead to buildup of nonwetting fluid phase (NWP) at interfaces between facies. Explicit representation of geological heterogeneity at the intermediate (cm-to-m) scale is a powerful approach to identify the key mechanisms that control multiphase flow dynamics in porous media. The ability to carefully control flow regime and permeability contrast at a scale that is relevant to CO2 plume dynamics in saline formations offers valuable information to understand immiscible displacement processes and provides a benchmark for mathematical models. To provide insight into the impact of capillary heterogeneity on flow dynamics and trapping efficiency of supercritical CO2 under successive drainage and imbibition conditions, we present an experimental investigation conducted in a synthetic sand reservoir. By mimicking the interplay of governing forces at reservoir conditions via application of surrogate fluids, we performed three immiscible displacement experiments to observe the entrapment of NWP in heterogeneous porous media. Capillary trapping performance is evaluated for each scenario through spatial and temporal variations of NWP saturation; for this reason we adopted X-ray attenuation to precisely measure phase saturation throughout the flow domain and apply spatial moment analysis. The sweeping performance of two different permeability fields with comparable variance but distinct spatial correlation was compared against a homogeneous base case with equivalent mean permeability by means of spatial moment analysis.

  20. Quantification of CO2-FLUID-ROCK Reactions Using Reactive and Non-Reactive Tracers

    NASA Astrophysics Data System (ADS)

    Matter, J.; Stute, M.; Hall, J. L.; Mesfin, K. G.; Gislason, S. R.; Oelkers, E. H.; Sigfússon, B.; Gunnarsson, I.; Aradottir, E. S.; Alfredsson, H. A.; Gunnlaugsson, E.; Broecker, W. S.

    2013-12-01

    Carbon dioxide mineralization via fluid-rock reactions provides the most effective and long-term storage option for geologic carbon storage. Injection of CO2 in geologic formations induces CO2 -fluid-rock reactions that may enhance or decrease the storage permanence and thus the long-term safety of geologic carbon storage. Hence, quantitative characterization of critical CO2 -fluid-rock interactions is essential to assess the storage efficiency and safety of geologic carbon storage. In an attempt to quantify in-situ fluid-rock reactions and CO2 transport relevant for geologic carbon storage, we are testing reactive (14C, 13C) and non-reactive (sodium fluorescein, amidorhodamine G, SF5CF3, and SF6) tracers in an ongoing CO2 injection in a basaltic storage reservoir at the CARBFIX pilot injection site in Iceland. At the injection site, CO2 is dissolved in groundwater and injected into a permeable basalt formation located 500-800 m below the surface [1]. The injected CO2 is labeled with 14C by dynamically adding calibrated amounts of H14CO3-solution into the injection stream in addition to the non-reactive tracers. Chemical and isotopic analyses of fluid samples collected in a monitoring well, reveal fast fluid-rock reactions. Maximum SF6 concentration in the monitoring well indicates the bulk arrival of the injected CO2 solution but dissolved inorganic carbon (DIC) concentration and pH values close to background, and a potentially lower 14C to SF6 ratio than the injection ratio suggest that most of the injected CO2 has reacted with the basaltic rocks. This is supported by δ13CDIC, which shows a drop from values close to the δ 13C of the injected CO2 gas (-3‰ VPDB) during breakthrough of the CO2 plume to subsequent more depleted values (-11.25‰ VPDB), indicating precipitation of carbonate minerals. Preliminary mass balance calculations using mixing relationships between the background water in the storage formation and the injected solution, suggest that

  1. The influence of supercritical carbon dioxide (SC-CO2) processing conditions on drug loading and physicochemical properties.

    PubMed

    Ahern, Robert J; Crean, Abina M; Ryan, Katie B

    2012-12-15

    Poor water solubility of drugs can complicate their commercialisation because of reduced drug oral bioavailability. Formulation strategies such as increasing the drug surface area are frequently employed in an attempt to increase dissolution rate and hence, improve oral bioavailability. Maximising the drug surface area exposed to the dissolution medium can be achieved by loading drug onto a high surface area carrier like mesoporous silica (SBA-15). The aim of this work was to investigate the impact of altering supercritical carbon dioxide (SC-CO(2)) processing conditions, in an attempt to enhance drug loading onto SBA-15 and increase the drug's dissolution rate. Other formulation variables such as the mass ratio of drug to SBA-15 and the procedure for combining the drug and SBA-15 were also investigated. A model drug with poor water solubility, fenofibrate, was selected for this study. High drug loading efficiencies were obtained using SC-CO(2), which were influenced by the processing conditions employed. Fenofibrate release rate was enhanced greatly after loading onto mesoporous silica. The results highlighted the potential of this SC-CO(2) drug loading approach to improve the oral bioavailability of poorly water soluble drugs. PMID:23041132

  2. Ceramic powder synthesis in supercritical fluids

    SciTech Connect

    Adkins, C.L.J.; Russick, E.M.; Cesarano, J; Tadros, M.E.; Voigt, J.A.

    1996-04-01

    Gas-phase processing plays an important role in the commercial production of a number of ceramic powders. These include titanium dioxide, carbon black, zinc oxide, and silicon dioxide. The total annual output of these materials is on the order of 2 million tons. The physical processes involved in gas-phase synthesis are typical of those involved in solution -phase synthesis: chemical reaction kinetics, mass transfer, nucleation, coagulation, and condensation. This report focuses on the work done under a Laboratory-Directed Research and Development (LDRD) project that explored the use of various high pressure techniques for ceramic powder synthesis. Under this project, two approaches were taken. First, a continuous flow, high pressure water reactor was built and studied for powder synthesis. And second, a supercritical carbon dioxide static reactor, which was used in conjunction with surfactants, was built and used to generate oxide powders.

  3. Supercritical fluid reactions for coal processing. Quarterly report, January 1, 1996--March 31, 1996

    SciTech Connect

    Eckert, C.A.

    1996-10-01

    Exciting opportunities exist for the application of supercritical fluid (SCF) reactions for the pre-treatment of coal. Utilizing reactants which resemble the organic nitrogen containing components of coal, we propose to develop a method to tailor chemical reactions in supercritical fluid solvents for the specific application of coal denitrogenation. The tautomeric equilibrium of a Schiff base was chosen as the model system and was investigated in supercritical ethane and cosolvent modified supercritical ethane.

  4. Supercritical fluid reactions for coal processing. Quarterly progress report, April 1, 1996--June 30, 1996

    SciTech Connect

    Eckert, C.A.

    1996-11-01

    Exciting opportunities exist for the application of supercritical fluid (SCF) reactions for the pre-treatment of coal. Utilizing reactants which resemble the organic nitrogen containing components of coal, we propose to develop a method to tailor chemical reactions in supercritical fluid solvents for the specific application of coal denitrogenation. The tautomeric equilibrium of a Schiff base was chosen as the model system and was investigated in supercritical ethane and cosolvent modified supercritical ethane.

  5. Comparison of a liquid solvent extraction technique and supercritical fluid extraction for the determination of alpha- and beta-carotene in vegetables.

    PubMed

    Marsili, R; Callahan, D

    1993-10-01

    An ethanol-pentane solvent extraction procedure and a supercritical CO2 extraction procedure are compared for the high-performance liquid chromatographic determination of alpha- and beta-carotene in vegetables. The vegetables tested included carrots, collard greens, turnips, turnip greens, kale, mustard greens, broccoli florets, zucchini, and squash. Homogenization of the sample prior to liquid or supercritical fluid extraction significantly improved recovery of the carotenoids. A combination of static and dynamic modes of extraction with ethanol modifier at 338 atm and 40 degrees C was necessary in order to achieve optimum recovery with the supercritical fluid procedure. beta-Carotene results with the supercritical CO2 procedure averaged 23% higher than results for the liquid extraction procedure. Only corn and carrots contained detectable levels of alpha-carotene, and, in both cases, liquid extraction yielded slightly higher results. Liquid extractions were performed in approximately 90 min, and supercritical fluid extractions were performed in 30 min; however, the supercritical fluid extractions procedure required less than 10 min of an analyst's time while the liquid extraction procedure was labor intensive. PMID:8245174

  6. Residual trapping of supercritical CO2 in oil-wet sandstone.

    PubMed

    Rahman, Taufiq; Lebedev, Maxim; Barifcani, Ahmed; Iglauer, Stefan

    2016-05-01

    Residual trapping, a key CO2 geo-storage mechanism during the first decades of a sequestration project, immobilizes micrometre sized CO2 bubbles in the pore network of the rock. This mechanism has been proven to work in clean sandstones and carbonates; however, this mechanism has not been proven for the economically most important storage sites into which CO2 will be initially injected at industrial scale, namely oil reservoirs. The key difference is that oil reservoirs are typically oil-wet or intermediate-wet, and it is clear that associated pore-scale capillary forces are different. And this difference in capillary forces clearly reduces the capillary trapping capacity (residual trapping) as we demonstrate here. For an oil-wet rock (water contact angle θ=130°) residual CO2 saturation SCO2,r (≈8%) was approximately halved when compared to a strongly water-wet rock (θ=0°; SCO2,r≈15%). Consequently, residual trapping is less efficient in oil-wet reservoirs. PMID:26871275

  7. Supercritical fluid carbon dioxide cleaning of plutonium parts

    SciTech Connect

    Hale, S.J.; Haschke, J.M.; Cox, L.E.

    1993-09-01

    Supercritical fluid (SCF) carbon dioxide (CO{sub 2}) is being evaluated for use as a cleaning solvent to replace 1,1,1-trichloroethane for the final cleaning of plutonium (Pu) parts. These parts must be free of organic residue to avoid corrosion in the stockpile. Thermodynamic and kinetic data for selected reactions of Pu metal are evaluated as a basis for assessing the risk of a violent exothermic reaction during the use of SCF CO{sub 2} on Pu. The need for considering kinetic behavior of a reaction in assessing its thermal risk is demonstrated. Weight difference data and results of xray photoelectron spectroscopy to evaluate the surface after exposure to the supercritical fluid show that SCF CO{sub 2} is an effective and compatible cleaning solvent.

  8. Supercritical CO2 generation of nanometric structure from Ocimum basilicum mucilage prepared for pharmaceutical applications.

    PubMed

    Akbari, Iman; Ghoreishi, Seyyed M; Habibi, Neda

    2015-04-01

    Plant-derived polymers are widely used in the pharmaceutical industry due to their emollient, lack of toxicity, and irritating nature and low cost. In this work, basil seed mucilage was dried using supercritical carbon dioxide phase inversion technique to form a nanometric structure. The obtained polymeric structures were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) method, and Fourier transform infrared spectroscopy (FTIR) and compared with the oven-derived sample group. It was demonstrated that the product morphology could be controlled by altering the composition of methanol which functioned as the co-solvent in the nonsolvent stream. The most homogeneous product (60-nm mean pore size diameter, 78 m(2)/g BET surface area with no agglomeration) was obtained with 2.5% methanol. The FTIR data showed that the presence of hydroxyl and carboxyl groups suggested the bioadhesive property of basil seed mucilage was good and many active pharmaceutical compounds might be loaded to the resultant nanometric structure to enhance drug release. Furthermore, the FTIR analyses indicated that the nature of the final product did not change during the supercritical drying procedure. PMID:25367001

  9. Surface and Electrochemical Behavior of HSLA in Supercritical CO2-H2O Environment

    SciTech Connect

    M. Ziomek-Moroz; G. R. Holcomb; J. Tylczak; J. Beck; M. Fedkin; S. Lvov

    2012-01-11

    General corrosion was observed on high strength low alloy carbon steel after electrochemical impedance spectroscopy experiments (EIS) performed in H{sub 2}O saturated with CO{sub 2} at 50 C and 15.2 MPa. However, general and localized were observed on the same material surfaces after the EIS experiments performed in supercritical CO{sub 2} containing approximately 6100 ppmv H{sub 2}O at 50 C and 15.2 MPa. The general corrosion areas were uniformly covered by the FeCO{sub 3}-like phase identified by X-ray diffraction (XRD). In the area of localized corrosion, XRD also revealed FeCO{sub 3}-rich islands embedded in {alpha}-iron. The energy dispersive X-ray (EDX) analysis revealed high concentrations of iron, carbon, and oxygen in the area affected by general corrosion and in the islands formed in the area of localized corrosion. The real and imaginary impedances were lower in H{sub 2}O saturated with CO{sub 2} than those in the supercritical CO{sub 2} containing the aqueous phase indicating faster corrosion kinetics in the former.

  10. Sulfur Isotope Analysis of Minerals and Fluids in a Natural CO2 Reservoir, Green River, Utah

    NASA Astrophysics Data System (ADS)

    Chen, F.; Kampman, N.; Bickle, M. J.; Busch, A.; Turchyn, A. V.

    2013-12-01

    Predicting the security of geological CO2 storage sites requires an understanding of the geochemical behavior of the stored CO2, especially of fluid-rock reactions in reservoirs, caprocks and fault zones. Factors that may influence geochemical behavior include co-injection of sulfur gases along with the CO2, either in acid-gas disposal or as contaminants in CO2 storage sites, and microbial activity, such as bacterial sulfate reduction. The latter may play an important role in buffering the redox chemistry of subsurface fluids, which could affect toxic trace metal mobilization and transport in acidic CO2-rich fluids. These processes involving sulfur are poorly understood. Natural CO2-reservoirs provide natural laboratories, where the flow and reactions of the CO2-charged fluids and the activity of microbial communities are integrated over sufficient time-scales to aid prediction of long-term CO2 storage. This study reports on sulfur isotope analyses of sulfate and sulfide minerals in rock core and in CO2-charged fluids collected from a stacked sequence of natural CO2 reservoirs at Green River, Utah. Scientific drilling adjacent to a CO2-degassing normal fault to a depth of 325m retrieved core and fluid samples from two CO2 reservoirs in the Entrada and Navajo Sandstones and from the intervening Carmel Formation caprock. Fluid samples were collected from CO2-charged springs that discharge through the faults. Sulfur exists as sulfate in the fluids, as sedimentary gypsum beds in the Carmel Formation, as remobilized gypsum veins within a fault damage zone in the Carmel Fm. and in the Entrada Sandstone, and as disseminated pyrite and pyrite-mineralized open fractures throughout the cored interval. We use the stable sulfur (δ34S) and oxygen (δ18OSO4) isotopes of the sulfate, gypsum, and pyrite to understand the source of sulfur in the reservoir as well as the timing of gypsum vein and pyrite formation. The hydration water of the gypsum is also reported to explore the

  11. Supercritical Fluid Assisted Synthesis and Processing of Carbon Nanotubes

    SciTech Connect

    Ye, Sufang; Wu, Fengming; Ye, Xiangrong; Lin, Yuehe

    2009-03-26

    Carbon nanotubes (CNTs) constitute one of the most fascinating nanomaterials with specific properties and enormous applications. Taking advantages of the unique properties of supercritical fluids (SCFs), various techniques have been developed to produce and process CNTs and related nanostructured materials when conventional techniques become unviable. Herein we propose a critical review of these SCF based techniques. The most relevant characteristics of each technique and the enabled novel structures and functions which are difficult to accomplish by traditional techniques are highlighted.

  12. Specific extraction of chromium(VI) using supercritical fluid extraction.

    PubMed

    Foy, G P; Pacey, G E

    2000-02-01

    In some situations, it is no longer sufficient to give a total concentration of a metal. Instead, what is required to understand the potential toxicity of a sample is the concentration of metal species or oxidation state. When developing species specific methods, the major concern is that the integrity of the species ratio is not changed. In other words, the sample preparation or the analytical method will not convert metal ions from one oxidation state to another. Normal extraction techniques and chromatography methods have shown some tendencies to change species ratios. An ideal extraction method would extract the metal efficiently while retaining the metal's oxidation state. The properties of supercritical fluids should approach the ideal of retention of oxidation states. For example, the need for speciation of chromium is obvious since Cr(III) is considered an essential element while Cr(VI) is thought to be toxic and carcinogenic. This paper presents the results of a species specific extraction of Cr(VI) using two different carbamate derivatives as the chelator. Supercritical fluid extraction (SFE) coupled with a fluorinated dithiocarbamate and a methanol modifier allows extraction of 1 ppm Cr(VI) from a solid matrix with a recovery level of 88.4+/-2.57% using the NIST standard sample. The optimized conditions using the HP 7680 supercritical fluid extractor were: 0.1 ml of methanol, 0.05 ml of pure water, and 0.01 g of chelate via a saturation chamber. PMID:18967865

  13. Supercritical Fluid Extraction of Plutonium and Americium from Soil

    SciTech Connect

    Fox, R.V.; Mincher, B.J.

    2002-05-23

    Supercritical fluid extraction (SFE) of plutonium and americium from soil was successfully demonstrated using supercritical fluid carbon dioxide solvent augmented with organophosphorus and beta-diketone complexants. Spiked Idaho soils were chemically and radiologically characterized, then extracted with supercritical fluid carbon dioxide at 2,900 psi and 65 C containing varying concentrations of tributyl phosphate (TBP) and thenoyltrifluoroacetone (TTA). A single 45 minute SFE with 2.7 mol% TBP and 3.2 mol% TTA provided as much as 88% {+-} 6.0 extraction of americium and 69% {+-} 5.0 extraction of plutonium. Use of 5.3 mol% TBP with 6.8 mol% of the more acidic beta-diketone hexafluoroacetylacetone (HFA) provided 95% {+-} 3.0 extraction of americium and 83% {+-} 5.0 extraction of plutonium in a single 45 minute SFE at 3,750 psi and 95 C. Sequential chemical extraction techniques were used to chemically characterize soil partitioning of plutonium and americium in pre-SFE soil samples. Sequential chemical extraction techniques demonstrated that spiked plutonium resides primarily (76.6%) in the sesquioxide fraction with minor amounts being absorbed by the oxidizable fraction (10.6%) and residual fractions (12.8%). Post-SFE soils subjected to sequential chemical extraction characterization demonstrated that 97% of the oxidizable, 78% of the sesquioxide and 80% of the residual plutonium could be removed using SFE. These preliminary results show that SFE may be an effective solvent extraction technique for removal of actinide contaminants from soil.

  14. In Situ 13C and 23Na Magic Angle Spinning NMR Investigation of Supercritical CO2 Incorporation in Smectite-Natural Organic Matter Composites

    SciTech Connect

    Bowers, Geoffrey M.; Hoyt, David W.; Burton, Sarah D.; Ferguson, Brennan O.; Varga, Tamas; Kirkpatrick, Robert J.

    2014-01-29

    This paper presents an in situ NMR study of clay-natural organic polymer systems (a hectoritehumic acid [HA] composite) under CO2 storage reservoir conditions (90 bars CO2 pressure, 50°C). The 13C and 23Na NMR data show that supercritical CO2 interacts more strongly with the composite than with the base clay and does not react to form other C-containing species over several days at elevated CO2. With and without organic matter, the data suggest that CO2 enters the interlayer space of Na-hectorite equilibrated at 43% relative humidity. The presence of supercritical CO2 also leads to increased 23Na signal intensity, reduced line width at half height, increased basal width, more rapid 23Na T1 relaxation rates, and a shift to more positive resonance frequencies. Larger changes are observed for the hectorite-HA composite than for the base clay. In light of recently reported MD simulations of other polymer-Na-smectite composites, we interpret the observed changes as an increase in the rate of Na+ site hopping in the presence of supercritical CO2, the presence of potential new Na+ sorption sites when the humic acid is present, and perhaps an accompanying increase in the number of Na+ ions actively involved in site hopping. The results suggest that the presence of organic material either in clay interlayers or on external particle surfaces can significantly affect the behavior of supercritical CO2 and the mobility of metal ions in reservoir rocks.

  15. Preparation and characterisation of hydrocortisone particles using a supercritical fluids extraction process.

    PubMed

    Velaga, Sitaram P; Ghaderi, Raouf; Carlfors, Johan

    2002-01-14

    Crystallisation and subsequent milling of pharmaceutical powders by traditional methods often cause variations in physicochemical properties thereby influencing bioavailability of the formulation. Crystallisation of drug substances using supercritical fluids (SFs) offers some advantages over existing traditional methods in controlling particle characteristics. The novel particle formation method, solution enhanced dispersion by supercritical (SEDS) fluids was used for the preparation of hydrocortisone (HC) particles. The influence of processing conditions on the solid-state properties of the particles was studied. HC, an anti-inflammatory corticosteroid, particles were prepared from acetone and methanol solutions using the SEDS process. The solutions were dispersed with supercritical CO(2), acting as an anti-solvent, through a specially designed co-axial nozzle into a pressured vessel maintained at a specific constant temperature and pressure. The temperatures and pressures studied were 40-90 degrees C and 90-180 bar, respectively. The relative flow rates of drug solution to CO(2) were varied between 0.002 and 0.03. Solid-state characterisation of particles included differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), solubility studies and scanning electron microscopy (SEM) examination. The aerodynamic properties of SEDS prepared particles were determined by a multistage liquid impinger (MLI). Particles produced from acetone solutions were crystalline needles, melting at 221+/-2 degrees C. Their morphology was independent of processing conditions. With methanol solutions, particles were flakes or needles depending on the processing temperature and pressure. This material melted at 216+/-1 degrees C, indicating a different crystal structure from the original material, in agreement with observed differences in the position and intensity of the XRPD peaks. The simulated lung deposition, using the MLI, for HC powder was improved after SEDS

  16. Magnetic resonance imaging study on near miscible supercritical CO2 flooding in porous media

    NASA Astrophysics Data System (ADS)

    Song, Yongchen; Zhu, Ningjun; Zhao, Yuechao; Liu, Yu; Jiang, Lanlan; Wang, Tonglei

    2013-05-01

    CO2 flooding is one of the most popular secondary or tertiary recoveries for oil production. It is also significant for studying the mechanisms of the two-phase and multiphase flow in porous media. In this study, an experimental study was carried out by using magnetic resonance imaging technique to examine the detailed effects of pressure and rates on CO2/decane flow in a bead-pack porous media. The displacing processes were conducted under various pressures in a region near the minimum miscibility pressure (the system tuned from immiscible to miscible as pressure is increasing in this region) and the temperature of 37.8 °C at several CO2 injection volumetric rates of 0.05, 0.10, and 0.15 ml/min (or linear rates of 3.77, 7.54, and 11.3 ft/day). The evolution of the distribution of decane and the characteristics of the two phase flow were investigated and analyzed by considering the pressure and rate. The area and velocity of the transition zone between the two phases were calculated and analyzed to quantify mixing. The area of transition zone decreased with pressure at near miscible region and a certain injection rate and the velocity of the transition zone was always less than the "volumetric velocity" due to mutual solution and diffusion of the two phases. Therefore, these experimental results give the fundamental understanding of tertiary recovery processes at near miscible condition.

  17. CO2 sequestration in feldspar-rich sandstone: Coupled evolution of fluid chemistry, mineral reaction rates, and hydrogeochemical properties

    NASA Astrophysics Data System (ADS)

    Tutolo, Benjamin M.; Luhmann, Andrew J.; Kong, Xiang-Zhao; Saar, Martin O.; Seyfried, William E.

    2015-07-01

    To investigate CO2 Capture, Utilization, and Storage (CCUS) in sandstones, we performed three 150 °C flow-through experiments on K-feldspar-rich cores from the Eau Claire formation. By characterizing fluid and solid samples from these experiments using a suite of analytical techniques, we explored the coupled evolution of fluid chemistry, mineral reaction rates, and hydrogeochemical properties during CO2 sequestration in feldspar-rich sandstone. Overall, our results confirm predictions that the heightened acidity resulting from supercritical CO2 injection into feldspar-rich sandstone will dissolve primary feldspars and precipitate secondary aluminum minerals. A core through which CO2-rich deionized water was recycled for 52 days decreased in bulk permeability, exhibited generally low porosity associated with high surface area in post-experiment core sub-samples, and produced an Al hydroxide secondary mineral, such as boehmite. However, two samples subjected to ∼3 day single-pass experiments run with CO2-rich, 0.94 mol/kg NaCl brines decreased in bulk permeability, showed generally elevated porosity associated with elevated surface area in post-experiment core sub-samples, and produced a phase with kaolinite-like stoichiometry. CO2-induced metal mobilization during the experiments was relatively minor and likely related to Ca mineral dissolution. Based on the relatively rapid approach to equilibrium, the relatively slow near-equilibrium reaction rates, and the minor magnitudes of permeability changes in these experiments, we conclude that CCUS systems with projected lifetimes of several decades are geochemically feasible in the feldspar-rich sandstone end-member examined here. Additionally, the observation that K-feldspar dissolution rates calculated from our whole-rock experiments are in good agreement with literature parameterizations suggests that the latter can be utilized to model CCUS in K-feldspar-rich sandstone. Finally, by performing a number of reactive

  18. Determination of N-nitrosamines in latex by sequential supercritical fluid extraction and derivatization.

    PubMed

    Reche, F; Garrigós, M C; Marín, M L; Jiménez, A

    2002-11-01

    A new method to determine N-nitrosamines in latex products has been developed by combination of supercritical fluids and chemical derivatization. A new design for a liquid trap has been introduced. A factorial fractional design was used in order to evaluate the influence of the different factors affecting the process. Factors such as pressure, temperature, static and dynamic time, restrictor temperature and volume of an hydrobromic acid-acetic anhydride mixture (1:10, v/v) were included in the design. CO2 was used as the extraction fluid. Gas chromatography with nitrogen and phosphorus sensitive detection was employed to achieve good sensitivity attending to the molecular structure of these compounds (N-nitrosamines and their corresponding secondary amines). The obtained results have shown to be useful to increase selectivity and reduce sample handling. PMID:12462622

  19. Trapping non-wettable fluid in porous rock: Implication to CO2 sequestration

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Yun, T.

    2013-12-01

    The residual saturation of CO2 mainly determines the effective storage capacity in geological formation whereas its transport and fate are dominated by fluid properties and pore characteristics. This experimental study evaluates the relative permeability of brine and non-wettable fluids in Berea sandstone. The surrogate fluids representing CO2 are continuously injected into the brine-saturated sandstone and the effluent is simultaneously separated to measure the residual volume. The variables under consideration include the viscosity and surface tension of injected fluids, porosity, anisotropy of rock, and injection pressure and the residual saturation of non-wettable fluids is quantified based on the proposed variables. Results highlight that the storage capacity can be readily modulated and maximized by controlling the cyclic injection, initial saturation of non-wettable fluids, and injection pressure.

  20. Simultaneous quantification of vitamin E, γ-oryzanols and xanthophylls from rice bran essences extracted by supercritical CO2.

    PubMed

    Sookwong, Phumon; Suttiarporn, Panawan; Boontakham, Pittayaporn; Seekhow, Pattawat; Wangtueai, Sutee; Mahatheeranont, Sugunya

    2016-11-15

    Since the nutrition value of rice is diminished during rice processing, technology that can preserve and sustain functional compounds is necessary. In this study, supercritical carbon dioxide (SC-CO2) extraction was optimized for operational conditions (time, temperature, pressure and modifier) to extract vitamin E, γ-oryzanols and xanthophylls from rice bran. The simultaneous quantification of the compounds was developed using high-performance liquid chromatography with diode array and fluorescence detectors. Central composite design and respond surface methodology were applied to achieve optimum extraction conditions. The optimized conditions were 60min, 43°C, 5420psi with 10% ethanol as a modifier. Pigmented rice bran extracts contained greater amounts of functional phytochemicals than non-pigmented rice bran extracts (0.68, 1410, and non-detectable μg/g compared with 16.65, 2480, and 0.10μg/g of vitamin E, γ-oryzanols and xanthophylls in pigmented and non-pigmented ones, respectively). SC-CO2 extraction with modifier would be promising for preparation of phytochemical essences for therapeutic purpose. PMID:27283617

  1. Comparison of supercritical fluid extraction (SFE), Soxhlet and shaking methods for pendimethalin extraction from soils: effect of soil properties and water content

    NASA Astrophysics Data System (ADS)

    Spack, Lionel; Alvarez, Cristina; Martins, Jean M. F.; Tarradellas, Joseph

    1998-09-01

    Supercritical fluid extraction with CO 2 was applied to the analysis of traces of pendimethalin, a herbicide of the dinitroanilines group, in four different natural soils. The Supercritical Fluid Extraction (SFE) method was compared with the classical Soxhlet and shaking methods in terms of ease to run, extraction efficiency, selectivity and reproducibility. The influence of the physico-chemical properties of the soil matrix on herbicide extraction was then evaluated with the SFE method. The supercritical fluid extraction system used in the present study was found to be much easier to run than the other two methods, less time consuming and requires fewer operations as it was optimized for on-line sample clean up. SFE is the most selective of the three tested methods as fewer co-extracts are obtained in the final samples. SFE with CO 2 is particularly powerful because pendimethalin is highly hydrophobic. However, this makes pendimethalin a poor choice for a selectivity study of SFE as it is very rapidly extracted at any CO 2 density. Pendimethalin extraction with supercritical CO 2 was found to be almost complete with average recoveries of 96-99%, similarly to Soxhlet but with a much lower standard deviation (8-10%). The performance of SFE was shown to be unaffected by soil parameters except soil water content. It is demonstrated indeed that extraction efficiency is not linearly related to soil water content, and optimal recovery was found for water contents ranging from 2 to 15% depending on the type of soil. Soil water increases extraction efficiency because water acts as a modifier of the supercritical fluid and increases the penetration of the fluid inside the soil particles (clay swelling). In contrast to SFE and Soxhlet, the efficiency of the shaking method appeared to be partial and strongly dependent on soil properties. Although initial developments should be needed, the various benefits of SFE-CO 2 make this method attractive compared to traditional methods.

  2. Development of supercritical fluid extraction and supercritical fluid chromatography purification methods using rapid solubility screening with multiple solubility chambers.

    PubMed

    Gahm, Kyung H; Huang, Ke; Barnhart, Wesley W; Goetzinger, Wolfgang

    2011-01-01

    Rapid solubility screening in diverse supercritical fluids (SCFs) was carried out via multiple solubility chambers with a trapping device and online ultraviolet (UV) detection. With this device, it was possible to rapidly study the solubility variations of multiple components in a mixture. Results from solubility studies have been used to develop efficient supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC) methods. After the investigation of solubilities of theophylline and caffeine in several neat organic solvents and SCFs, advantages of SFE over conventional organic solvent extraction were demonstrated with a model mixture of theophylline and caffeine. The highest solubility ratio of 1:40 (theophylline:caffeine) was observed in the SCF with 20% acetonitrile (MeCN), where a ratio of 1:11 was the highest in the neat organic solvents. A model mixture of theophylline:caffeine (85:15 w/w, caffeine as an impurity) was successfully purified by SFE by leveraging the highest solubility difference. The SCF with 20% MeCN selectively removed caffeine and left theophylline largely intact. Rapid SCF solubility screening was applied to development of SFE and SFC methods in a drug discovery environment. Two successful applications were demonstrated with proprietary Amgen compounds to either remove an achiral impurity before chiral purification or enhance chiral chromatographic throughput. PMID:21766341

  3. Evidence for CO2-rich fluids in rocks from the type charnockite area near Pallavaram, Tamil Nadu

    NASA Technical Reports Server (NTRS)

    Hansen, E.; Hunt, W.; Jacob, S. C.; Morden, K.; Reddi, R.; Tacy, P.

    1988-01-01

    Fluid inclusion and mineral chemistry data was presented for samples from the type charnockite area near Pallavaram (Tamil Nadu, India). The results indicate the presence of a dense CO2 fluid phase, but the data cannot distinguish between influx of this fluid from elsewhere or localized migration of CO2-rich fluids associated with dehydration melting.

  4. SELECTIVE HYDROGENATION OF MALEIC ANHYDRIDE TO Y-BUTYROLACTONE OVER PD/AL(2)O(3) CATALYST USING SUPERCRITICAL CO(2) AS SOLVENT

    EPA Science Inventory

    A selective hydrogenation of maleic anhydride to either y-butyrolactone or succinic anhydride over simple Pd/Al(2)O(3) catalyst under supercritical CO(2) medium is described for the first time which has considerable promise for obht lab-scale as well as industrial selective hydro...

  5. Summarizing the effectiveness of supercritical fluid extraction of polycyclic aromatic hydrocarbons from natural matrix environmental samples.

    PubMed

    Benner, B A

    1998-11-01

    A summary of the supercritical fluid extraction (SFE) of polycyclic aromatic hydrocarbons (PAHs) from four natural matrix Standard Reference Materials (SRMs) is presented. The work involved the investigation of the effects of extraction fluid [carbon dioxide (CO(2)), chlorodifluoromethane (R22), and 1,1,1,2-tetrafluoroethane (HFC134a)], fluid modifier (dichloromethane and aniline), temperature (60, 150, and 200 °C) and added water on the SFE recoveries of PAHs compared to certified results from Soxhlet extractions. For SRM 1649a (Urban Dust/Organics), R22 yielded excellent recoveries (>90% of certified concentrations) of all PAHs measured, while results for the same SRM using HFC134a as the fluid were typically <80% of the certified concentrations for most of the PAHs measured. For SRM 1941a and 1944, both aquatic sediments with similar physical and chemical compositions, extractions of the wet materials with dichloromethane-modified CO(2) (10%, v/v) yielded quantitative recoveries of all PAHs for SRM 1944 but an obvious trend of lower recoveries for higher molecular weight PAHs (≥228 amu) for SRM 1941a. Results of SFEs of SRM 1650 (Diesel Particulate Matter) showed that this material is the most refractory of the SRMs investigated in this study, with recoveries of indeno[1,2,3-cd]pyrene and benzo[ghi]perylene at <20% of the Soxhlet results. PMID:21644698

  6. The key to commercial-scale geological CO2 sequestration: Displaced fluid management

    USGS Publications Warehouse

    Surdam, R.C.; Jiao, Z.; Stauffer, P.; Miller, T.

    2011-01-01

    The Wyoming State Geological Survey has completed a thorough inventory and prioritization of all Wyoming stratigraphic units and geologic sites capable of sequestering commercial quantities of CO2 (5-15 Mt CO 2/year). This multi-year study identified the Paleozoic Tensleep/Weber Sandstone and Madison Limestone (and stratigraphic equivalent units) as the leading clastic and carbonate reservoir candidates for commercial-scale geological CO2 sequestration in Wyoming. This conclusion was based on unit thickness, overlying low permeability lithofacies, reservoir storage and continuity properties, regional distribution patterns, formation fluid chemistry characteristics, and preliminary fluid-flow modeling. This study also identified the Rock Springs Uplift in southwestern Wyoming as the most promising geological CO2 sequestration site in Wyoming and probably in any Rocky Mountain basin. The results of the WSGS CO2 geological sequestration inventory led the agency and colleagues at the UW School of Energy Resources Carbon Management Institute (CMI) to collect available geologic, petrophysical, geochemical, and geophysical data on the Rock Springs Uplift, and to build a regional 3-D geologic framework model of the Uplift. From the results of these tasks and using the FutureGen protocol, the WSGS showed that on the Rock Springs Uplift, the Weber Sandstone has sufficient pore space to sequester 18 billion tons (Gt) of CO2, and the Madison Limestone has sufficient pore space to sequester 8 Gt of CO2. ?? 2011 Published by Elsevier Ltd.

  7. Reaction of Water-Saturated Supercritical CO2 with Forsterite: Evidence for Magnesite Formation at Low Temperatures

    SciTech Connect

    Felmy, Andrew R.; Qafoku, Odeta; Arey, Bruce W.; Hu, Jian Z.; Hu, Mary Y.; Schaef, Herbert T.; Ilton, Eugene S.; Hess, Nancy J.; Pearce, Carolyn I.; Feng, Ju; Rosso, Kevin M.

    2012-08-01

    The nature of the reaction products that form on the surfaces of nanometer-sized forsterite particles during reaction with H2O saturated supercritical CO2 (scCO2) at 35 C and 50 C were examined under in situ conditions and ex situ following reaction. The in situ analysis was conducted by X-ray diffraction (XRD). Ex situ analysis consisted of scanning electron microscopy (SEM) examination of the surface phases and chemical characterization of precipitates using a combination of confocal Raman spectroscopy, 13C and 29Si NMR spectroscopy, and energy-dispersive X-ray Spectroscopy (EDS). The results show that the forsterite surface is highly reactive with the primary reaction products being a mixture of nesquehonite (MgCO3.3H2O) and magnesite (MgCO3) at short reaction times ({approx}3-4 days) and then magnesite (MgCO3) and a highly porous amorphous silica phase at longer reaction times (14 days). After 14 days of reaction most of the original forsterite transformed to reaction products. Importantly, the formation of magnesite was observed at temperatures much lower (35 C) than previously thought needed to overcome its well known sluggish precipitation kinetics. The conversion of nesquehonite to magnesite liberates H2O which can potentially facilitate further metal carbonation, as postulated by previous investigators, based upon studies at higher temperature (80 C). The observation that magnesite can form at lower temperatures implies that water recycling may also be important in determining the rate and extent of mineral carbonation in a wide range of potential CO2 storage reservoirs.

  8. Chemical modification of nanometric TiO2 particles by anchoring functional silane molecules in supercritical CO2

    NASA Astrophysics Data System (ADS)

    López-Periago, Ana M.; Sandoval, Wendy; Domingo, Concepción

    2014-03-01

    Supercritical carbon dioxide (scCO2) was used as a green solvent for the grafting of complex functional organosilanes containing nitrogen moieties on titanium dioxide (TiO2) nanoparticles using two strategies. The first strategy involved the preparation of two functional silanes, 4-nitrophenyl-(3-(trimethoxysilyl)-propyl)methanimine (NPTMS) and 4-(((3-(trimethoxysilyl)propyl)imino)methyl)-benzaldehyde (FPTMS) and further deposited under anhydrous conditions and scCO2 onto the TiO2 surface. The second strategy involved the scCO2 anhydrous deposition of bifunctional commercial silanes on the TiO2 surface. Two structures were synthesized. The first consisted in grafted TiO2 nanoparticles prepared by addition of the ligand, ((1R,2R)-N-(pyridin-2-ylmethyl)-2-(((E)-pyridin-2-ylmethylene) amino)-cyclohexan-1-amine (LPy-red), and designated as Ti-Cl-LPy-red. The second structure was synthesized by the reaction of (1,2)-diaminocylohexane (Dac), through the reactive site of 3-(Trimethoxysilyl)propyl methacrylate (MPTMS) previously deposited on the TiO2 surface and designated as Ti-MP-Dac. The synthesized silanes were characterized by ATR-FT and NMR spectroscopies and mass spectrometry. ATR-FT spectroscopy confirmed the presence of the silanes on the surface of the hybrid nanoparticles. Thermogravimetic analysis was used to estimate the loading of the silane grafted through both hydrogen and covalent bonding on the TiO2 surface. Further characterization of the solid samples was done by N2 adsorption-desorption and UV-vis diffuse reflectance.

  9. Proapoptotic and Antimetastatic Properties of Supercritical CO2 Extract of Nigella sativa Linn. Against Breast Cancer Cells

    PubMed Central

    Baharetha, Hussein M.; Nassar, Zeyad D.; Aisha, Abdalrahim F.; Ahamed, Mohamed B. Khadeer; Al-Suede, Foaud Saleih R.; Kadir, Mohd Omar Abd; Ismail, Zhari

    2013-01-01

    Abstract Nigella sativa, commonly referred as black cumin, is a popular spice that has been used since the ancient Egyptians. It has traditionally been used for treatment of various human ailments ranging from fever to intestinal disturbances to cancer. This study investigated the apoptotic, antimetastatic, and anticancer activities of supercritical carbon dioxide (SC-CO2) extracts of the seeds of N. sativa Linn. against estrogen-dependent human breast cancer cells (MCF-7). Twelve extracts were prepared from N. sativa seeds using the SC-CO2 extraction method by varying pressure and temperature. Extracts were analyzed using FTIR and UV-Vis spectrometry. Cytotoxicity of the extracts was evaluated on various human cancer and normal cell lines. Of the 12 extracts, 1 extract (A3) that was prepared at 60°C and 2500 psi (∼17.24 MPa) showed selective antiproliferative activity against MCF-7 cells with an IC50 of 53.34±2.15 μg/mL. Induction of apoptosis was confirmed by evaluating caspases activities and observing the cells under a scanning electron microscope. In vitro antimetastatic properties of A3 were investigated by colony formation, cell migration, and cell invasion assays. The elevated levels of caspases in A3 treated MCF-7 cells suggest that A3 is proapoptotic. Further nuclear condensation and fragmentation studies confirmed that A3 induces cytotoxicity through the apoptosis pathway. A3 also demonstrated remarkable inhibition in migration and invasion assays of MCF-7 cells at subcytotoxic concentrations. Thus, this study highlights the therapeutic potentials of SC-CO2 extract of N. sativa in targeting breast cancer. PMID:24328702

  10. Reaction of water-saturated supercritical CO2 with forsterite: Evidence for magnesite formation at low temperatures

    NASA Astrophysics Data System (ADS)

    Felmy, Andrew R.; Qafoku, Odeta; Arey, Bruce W.; Hu, Jian Zhi; Hu, Mary; Todd Schaef, H.; Ilton, Eugene S.; Hess, Nancy J.; Pearce, Carolyn I.; Feng, Ju; Rosso, Kevin M.

    2012-08-01

    The nature of the reaction products that form on the surfaces of nanometer-sized forsterite particles during reaction with H2O-saturated supercritical CO2 (scCO2) at 35 °C and 50 °C were examined under in situ conditions and ex situ following reaction. The in situ analysis was conducted by X-ray diffraction (XRD). Ex situ analysis consisted of scanning electron microscopy (SEM) examination of the surface phases and chemical characterization of precipitates using a combination of confocal Raman spectroscopy, 13C and 29Si NMR spectroscopy, and energy-dispersive X-ray spectroscopy (EDS). The results show that the forsterite surface is highly reactive with the primary reaction products being a mixture of nesquehonite (MgCO3·3H2O) and magnesite (MgCO3) at short reaction times (˜3-4 days) and then magnesite (MgCO3) and a highly porous amorphous silica phase at longer reaction times (14 days). After 14 days of reaction most of the original forsterite transformed to reaction products. Importantly, the formation of magnesite was observed at temperatures much lower (35 °C) than previously thought needed to overcome its well-known sluggish precipitation kinetics. The conversion of nesquehonite to magnesite liberates H2O which can potentially facilitate further metal carbonation, as postulated by previous investigators, based upon studies at higher temperature (80 °C). The observation that magnesite can form at lower temperatures implies that water recycling may also be important in determining the rate and extent of mineral carbonation in a wide range of potential CO2 storage reservoirs.

  11. Supercritical fluid technology. (Latest citations from the Biobusiness database). Published Search

    SciTech Connect

    1995-12-01

    The bibliography contains citations concerning applications of supercritical fluid technology. Topics include supercritical fluid technology use in chromatographic analysis, removal of cholesterol and caffeine from food products, extraction of essential oils, extraction of pesticide and other toxic contaminants from soil and food, and food analysis. Supercritical fluid technology patents and uses in the pharmaceutical industry are also described.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  12. Economic Assessment of Supercritical CO2 Extraction of Waxes as Part of a Maize Stover Biorefinery

    PubMed Central

    Attard, Thomas M.; McElroy, Con Robert; Hunt, Andrew J.

    2015-01-01

    To date limited work has focused on assessing the economic viability of scCO2 extraction to obtain waxes as part of a biorefinery. This work estimates the economic costs for wax extraction from maize stover. The cost of manufacture (COM) for maize stover wax extraction was found to be €88.89 per kg of wax, with the fixed capital investment (FCI) and utility costs (CUT) contributing significantly to the COM. However, this value is based solely on scCO2 extraction of waxes and does not take into account the downstream processing of the biomass following extraction. The cost of extracting wax from maize stover can be reduced by utilizing pelletized leaves and combusting the residual biomass to generate electricity. This would lead to an overall cost of €10.87 per kg of wax (based on 27% combustion efficiency for electricity generation) and €4.56 per kg of wax (based on 43% combustion efficiency for electricity generation). A sensitivity analysis study showed that utility costs (cost of electricity) had the greatest effect on the COM. PMID:26263976

  13. Economic Assessment of Supercritical CO2 Extraction of Waxes as Part of a Maize Stover Biorefinery.

    PubMed

    Attard, Thomas M; McElroy, Con Robert; Hunt, Andrew J

    2015-01-01

    To date limited work has focused on assessing the economic viability of scCO2 extraction to obtain waxes as part of a biorefinery. This work estimates the economic costs for wax extraction from maize stover. The cost of manufacture (COM) for maize stover wax extraction was found to be € 88.89 per kg of wax, with the fixed capital investment (FCI) and utility costs (CUT) contributing significantly to the COM. However, this value is based solely on scCO2 extraction of waxes and does not take into account the downstream processing of the biomass following extraction. The cost of extracting wax from maize stover can be reduced by utilizing pelletized leaves and combusting the residual biomass to generate electricity. This would lead to an overall cost of € 10.87 per kg of wax (based on 27% combustion efficiency for electricity generation) and €4.56 per kg of wax (based on 43% combustion efficiency for electricity generation). A sensitivity analysis study showed that utility costs (cost of electricity) had the greatest effect on the COM. PMID:26263976

  14. Experimental Insights into Multiphase (H2O-CO2) Fluid-Rock Interactions in Geothermal Systems

    NASA Astrophysics Data System (ADS)

    Kaszuba, J. P.; Lo Re, C.; Martin, J.; McPherson, B. J.; Moore, J. N.

    2012-12-01

    Integrated hydrothermal experiments and geochemical modeling elucidate fluid-rock interactions and reaction pathways in both natural and anthropogenic systems, including enhanced geothermal systems (EGS) in which CO2 is introduced as a working fluid. Experiments are conducted in rocker bombs and flexible Au-Ti reaction cells. Individual experiments require one to three months to complete; intensive in-situ fluid/gas sampling gauges reaction progress. Investigation of granitic reservoirs and associated vein minerals are broadly based on the Roosevelt Hot Springs thermal area, Utah, USA. The granite consists of subequal amounts of quartz, perthitic K-feldspar (~25% wt% albite and 75% wt% K-feldspar), and oligoclase (An23), and 4 wt% Fe-rich biotite. Vein minerals include epidote and chlorite (clinochlore). Experiments are conducted at 250°C and 25 to 45 MPa. Each experiment uses mineral powders (75 wt% of rock mass, ground to <45 um) to increase reactivity and also mineral pieces (0.1-0.7 cm in size) to promote petrologic evaluation of mineral reactions. The water (I ≈ 0.1 molal) initially contains millimolal quantities of SiO2, Al, Ca, Mg, K, SO4, and HCO3 and is designed to be saturated with all of the minerals present at the start of each experiment. Excess CO2 is injected to saturate the water and maintain an immiscible supercritical fluid phase. The entire evolutionary path of the natural system is not replicated at laboratory scales. Instead, experiments define a segment of the reaction path and, in combination with geochemical modeling, provide clear trajectories towards equilibrium. Reaction of granite+water yields illite+zeolite; smectite subsequently precipitates in response to CO2 injection. Reaction of granite+epidote+water yields illite+zeolite+smectite; zeolite does not precipitate after CO2 is injected. Water in all experiments become saturated with chalcedony. Carbonate minerals do not precipitate but are predicted as final equilbrium products

  15. Characterization of the CO2 fluid adsorption in coal as a function of pressure using neutron scattering techniques (SANS and USANS)

    USGS Publications Warehouse

    Melnichenko, Y.B.; Radlinski, A.P.; Mastalerz, Maria; Cheng, G.; Rupp, J.

    2009-01-01

    Small angle neutron scattering techniques have been applied to investigate the phase behavior of CO2 injected into coal and possible changes in the coal pore structure that may result from this injection. Three coals were selected for this study: the Seelyville coal from the Illinois Basin (Ro = 0.53%), Baralaba coal from the Bowen Basin (Ro = 0.67%), and Bulli 4 coal from the Sydney Basin (Ro = 1.42%). The coals were selected from different depths to represent the range of the underground CO2 conditions (from subcritical to supercritical) which may be realized in the deep subsurface environment. The experiments were conducted in a high pressure cell and CO2 was injected under a range of pressure conditions, including those corresponding to in-situ hydrostatic subsurface conditions for each coal. Our experiments indicate that the porous matrix of all coals remains essentially unchanged after exposure to CO2 at pressures up to 200??bar (1??bar = 105??Pa). Each coal responds differently to the CO2 exposure and this response appears to be different in pores of various sizes within the same coal. For the Seelyville coal at reservoir conditions (16????C, 50??bar), CO2 condenses from a gas into liquid, which leads to increased average fluid density in the pores (??pore) with sizes (r) 1 ?? 105 ??? r ??? 1 ?? 104???? (??pore ??? 0.489??g/cm3) as well as in small pores with size between 30 and 300???? (??pore ??? 0.671??g/cm3). These values are by a factor of three to four higher than the density of bulk CO2 (??CO2) under similar thermodynamic conditions (??CO2 ??? 0.15??g/cm3). At the same time, in the intermediate size pores with r ??? 1000???? the average fluid density is similar to the density of bulk fluid, which indicates that adsorption does not occur in these pores. At in situ conditions for the Baralaba coal (35 OC, 100??bar), the average fluid density of CO2 in all pores is lower than that of the bulk fluid (??pore / ??CO2 ??? 0.6). Neutron scattering from the

  16. Conductivity measurements on H2O-bearing CO2-rich fluids

    DOE PAGESBeta

    Capobianco, Ryan M.; Miroslaw S. Gruszkiewicz; Bodnar, Robert J.; Rimstidt, J. Donald

    2014-09-10

    Recent studies report rapid corrosion of metals and carbonation of minerals in contact with carbon dioxide containing trace amounts of dissolved water. One explanation for this behavior is that addition of small amounts of H2O to CO2 leads to significant ionization within the fluid, thus promoting reactions at the fluid-solid interface analogous to corrosion associated with aqueous fluids. The extent of ionization in the bulk CO2 fluid was determined using a flow-through conductivity cell capable of detecting very low conductivities. Experiments were conducted from 298 to 473 K and 7.39 to 20 MPa with H2O concentrations up to ~1600 ppmwmore » (xH2O ≈ 3.9 x 10-3), corresponding to the H2O solubility limit in liquid CO2 at ambient temperature. All solutions showed conductivities <10 nS/cm, indicating that the solutions were essentially ion-free. Furthermore, this observation suggests that the observed corrosion and carbonation reactions are not the result of ionization in CO2-rich bulk phase, but does not preclude ionization in the fluid at the fluid-solid interface.« less

  17. Modeling and experimental results for condensing supercritical CO2 power cycles.

    SciTech Connect

    Wright, Steven Alan; Conboy, Thomas M.; Radel, Ross F.; Rochau, Gary Eugene

    2011-01-01

    This Sandia supported research project evaluated the potential improvement that 'condensing' supercritical carbon dioxide (S-CO{sub 2}) power cycles can have on the efficiency of Light Water Reactors (LWR). The analytical portion of research project identified that a S-CO{sub 2} 'condensing' re-compression power cycle with multiple stages of reheat can increase LWR power conversion efficiency from 33-34% to 37-39%. The experimental portion of the project used Sandia's S-CO{sub 2} research loop to show that the as designed radial compressor could 'pump' liquid CO{sub 2} and that the gas-cooler's could 'condense' CO{sub 2} even though both of these S-CO{sub 2} components were designed to operate on vapor phase S-CO{sub 2} near the critical point. There is potentially very high value to this research as it opens the possibility of increasing LWR power cycle efficiency, above the 33-34% range, while lowering the capital cost of the power plant because of the small size of the S-CO{sub 2} power system. In addition it provides a way to incrementally build advanced LWRs that are optimally designed to couple to S-CO{sub 2} power conversion systems to increase the power cycle efficiency to near 40%.

  18. Investigations of Localized Corrosion of Stainless Steel after Exposure to Supercritical CO2

    SciTech Connect

    M. Ziomek-Moroz; W. O’Connor; S. Bullard

    2012-03-11

    Severe localized corrosion of a 316 stainless steel autoclave occurred during investigating Type H Portland cement stability in 0.16 M CaCl{sub 2} + 0.02 M MgCl{sub 2} + 0.82 M NaCl brine in contact with supercritical CO{sub 2} containing 4% O{sub 2}. The system operated at 85 C and pressure of 29 MPa. However, no corrosion was observed in the same type of autoclave being exposed to the same environment, containing Type H Portland cement cylindrical samples, also operating at pressure of 29 MPa but at 50 C. The operation time for the 85 C autoclave was 53 days (1272 hours) while that for the 50 C autoclave was 66 days (1584 hours). Debris were collected from the base of both autoclaves and analyzed by X-ray diffraction (XRD). Corrosion products were only found in the debris from the 85 C autoclave. The cement samples were analyzed before and after the exposure by X-ray florescence (XRF) methods. Optical microscopy was used to estimate an extent of the 316 stainless steel corrosion degradation.

  19. Improved neuroprotective effects by combining Bacopa monnieri and Rosmarinus officinalis supercritical CO2 extracts.

    PubMed

    Ramachandran, Cheppail; Quirin, Karl-Werner; Escalon, Enrique; Melnick, Steven J

    2014-04-01

    Ethnobotanical evidence suggests that herbs such as brahmi (Bacopa monnieri) and rosemary (Rosmarinus officinalis) may possess antioxidant and neuroprotective properties. We compared the antioxidant and neuroprotective effects of supercritical extract of Bacopa monnieri and rosemary antioxidant extract obtained from Rosmarinus officinalis as well as their combination to examine the effects on human glial (U-87 MG) and embryonic mouse hypothalamus cells. Bacopa monnieri extract, rosemary antioxidant extract, and their combination (1:1) are not cytotoxic in both glial and embryonic mouse hypothalamus cell lines up to 200 μg/mL concentration. The combination of extracts of Bacopa monnieri + rosemary antioxidant has better antioxidant potential and antilipid peroxidation activity than either agent alone. Although the extract of Bacopa monnieri + rosemary antioxidant showed almost similar inhibition of phospho tau expression as Bacopa monnieri or rosemary antioxidant extract alone, the combination has better inhibitory effect on amyloid precursor protein synthesis and higher brain-derived neurotrophic factor production in hypothalamus cells than single agents. These results suggest that the extract of Bacopa monnieri + rosemary antioxidant is more neuroprotective than Bacopa monnieri or rosemary antioxidant extract. PMID:24647092

  20. Coupled Model for CO2 Leaks from Geological Storage: Geomechanics, Fluid Flow and Phase Transitions

    NASA Astrophysics Data System (ADS)

    Gor, G.; Prevost, J.

    2013-12-01

    Deep saline aquifers are considered as a promising option for long-term storage of carbon dioxide. However, risk of CO2 leakage from the aquifers through faults, natural or induced fractures or abandoned wells cannot be disregarded. Therefore, modeling of various leakage scenarios is crucial when selecting a site for CO2 sequestration and choosing proper operational conditions. Carbon dioxide is injected into wells at supercritical conditions (t > 31.04 C, P > 73.82 bar), and these conditions are maintained in the deep aquifers (at 1-2 km depth) due to hydrostatic pressure and geothermal gradient. However, if CO2 and brine start to migrate from the aquifer upward, both pressure and temperature will decrease, and at the depth of 500-750 m, the conditions for CO2 will become subcritical. At subcritical conditions, CO2 starts boiling and the character of the flow changes dramatically due to appearance of the third (vapor) phase and latent heat effects. When modeling CO2 leaks, one needs to couple the multiphase flow in porous media with geomechanics. These capabilities are provided by Dynaflow, a finite element analysis program [1]; Dynaflow has already showed to be efficient for modeling caprock failure causing CO2 leaks [2, 3]. Currently we have extended the capabilities of Dynaflow with the phase transition module, based on two-phase and three-phase isenthalpic flash calculations [4]. We have also developed and implemented an efficient method for solving heat and mass transport with the phase transition using our flash module. Therefore, we have developed a robust tool for modeling CO2 leaks. In the talk we will give a brief overview of our method and illustrate it with the results of simulations for characteristic test cases. References: [1] J.H. Prevost, DYNAFLOW: A Nonlinear Transient Finite Element Analysis Program. Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ. http://www.princeton.edu/~dynaflow/ (last update 2013

  1. Modeling of supercritical fluid extraction from herbaceous matrices

    SciTech Connect

    Reverchon, E.; Donsi, G.; Osseo, L.S. . Dipt. di Ingegneria Chimica e Alimentare)

    1993-11-01

    Experimental results of supercritical fluid extraction from various herbaceous matrices are presented. In optimal extraction conditions, the use of a fractional separation technique allows a nearly complete separation of the extract in cuticular waxes and essential oil. The modeling of these results is proposed starting from the description of the mass transfer from a single spherical particle. The simultaneous extraction of two pseudocompounds is assumed to simulate the two compound families obtained by fractionation. The model is then extended to simulate the whole extractor. The yields of essential oil and cuticular waxes obtained from rosemary, basil, and marjoram leaves are fairly simulated by the model. Intraparticle mass transfer resulted as the controlling stage in supercritical extraction of essential oils.

  2. Preparation of cefpodoxime proxetil fine particles using supercritical fluids.

    PubMed

    Chu, Junho; Li, Guanghua; Row, Kyung Ho; Kim, Hwayong; Lee, Youn-Woo

    2009-03-18

    Fine particles of cefpodoxime proxetil (CPD) were prepared using an Aerosol Solvent Extraction System (ASES) with supercritical CO(2). The resulting primary particles were approximately 0.1-0.2microm in size and were almost spherical in shape. The secondary particles were approximately 0.2-0.6microm in size and had irregular shapes. The larger particle size and irregular shapes were due to the agglomeration of the primary particles. The effects of solvent type, CO(2)-to-CPD solution weight ratio, and CPD solution concentration on the extent of agglomeration were investigated. As a result, the use of ethyl acetate and acetone as solvents also reduced the degree of agglomeration. The degree of agglomeration was reduced with the use of a high CO(2)-to-solution weight ratio, and a low solution concentration. In particular, spherical particles, approximately 0.1-0.4microm in size, were obtained when a 10.0wt% CPD solution was used. As a result of dissolution study, almost 90% of the processed CPD had dissolved within 10min. The recovery yield of the CPD powder reached approximately 80% using a membrane filter. PMID:19041383

  3. Numerical Studies of Fluid Leakage from a Geologic DisposalReservoir for CO2 Show Self-Limiting Feedback between Fluid Flow and HeatTransfer

    SciTech Connect

    Pruess, Karsten

    2005-03-22

    Leakage of CO2 from a hypothetical geologic storage reservoir along an idealized fault zone has been simulated, including transitions between supercritical, liquid, and gaseous CO2. We find strong non-isothermal effects due to boiling and Joule-Thomson cooling of expanding CO2. Leakage fluxes are limited by limitations in conductive heat transfer to the fault zone. The interplay between multiphase flow and heat transfer effects produces non-monotonic leakage behavior.

  4. Carbon dioxide-based supercritical fluids as IC manufacturing solvents

    SciTech Connect

    Rubin, J.B.; Davenhall, L.B.; Taylor, C.M.V.; Sivils, L.D.; Pierce, T.; Tiefert, K.

    1999-05-11

    The production of integrated circuits (IC's) involves a number of discrete steps which utilize hazardous or regulated solvents and generate large waste streams. ES&H considerations associated with these chemicals have prompted a search for alternative, more environmentally benign solvent systems. An emerging technology for conventional solvent replacement is the use of supercritical fluids based on carbon dioxide (CO{sub 2}). Research work, conducted at Los Alamos in conjunction with the Hewlett-Packard Company, has lead to the development of a CO{sub 2}-based supercritical fluid treatment system for the stripping of hard-baked photoresists. This treatment system, known as Supercritical CO{sub 2} Resist Remover, or CORR, uses a two-component solvent composed of a nonhazardous, non-regulated compound, dissolved in supercritical CO{sub 2}. The solvent/treatment system has been successfully tested on metallized Si wafers coated with negative and positive photoresist, the latter both before and after ion-implantation. A description of the experimental data will be presented. Based on the initial laboratory results, the project has progressed to the design and construction of prototype, single-wafer photoresist-stripping equipment. The integrated system involves a closed-loop, recirculating cycle which continuously cleans and regenerates the CO{sub 2}, recycles the dissolved solvent, and separates and concentrates the spent resist. The status of the current design and implementation strategy of a treatment system to existing IC fabrication facilities will be discussed. Additional remarks will be made on the use of a SCORR-type system for the cleaning of wafers prior to processing.

  5. Reservoir fluid and gas chemistry during CO2 injection at the Cranfield field, Mississippi, USA

    NASA Astrophysics Data System (ADS)

    Lu, J.; Kharaka, Y. K.; Cole, D. R.; Horita, J.; Hovorka, S.

    2009-12-01

    At Cranfield field, Mississippi, USA, a monitored CO2-EOR project provides a unique opportunity to understand geochemical interactions of injected CO2 within the reservoir. Cranfield field, discovered in 1943, is a simple anticlinal four-way closure and had a large gas cap surrounded by an oil ring (Mississippi Oil and Gas Board, 1966). The field was abandoned in 1966. The reservoir returned to original reservoir pressure (hydrostatic pressure) by a strong aquifer drive by 2008. The reservoir is in the lower Tuscaloosa Formation at depths of more than 3000 m. It is composed of stacked and incised channel fills and is highly heterogeneous vertically and horizontally. A variable thickness (5 to 15 m) of terrestrial mudstone directly overlies the basal sandstone providing the primary seal, isolating the injection interval from a series of fluvial sand bodies occurring in the overlying 30 m of section. Above these fluvial channels, the marine mudstone of the Middle Tuscaloosa forms a continuous secondary confining system of approximately 75 m. The sandstones of the injection interval are rich in iron, containing abundant diagenetic chamosite (ferroan chlorite), hematite and pyrite. Geochemical modeling suggests that the iron-bearing minerals will be dissolved in the face of high CO2 and provide iron for siderite precipitation. CO2 injection by Denbury Resources Inc. begun in mid-July 2008 on the north side of the field with rates at ~500,000 tones per year. Water and gas samples were taken from seven production wells after eight months of CO2 injection. Gas analyses from three wells show high CO2 concentrations (up to 90 %) and heavy carbon isotopic signatures similar to injected CO2, whereas the other wells show original gas composition and isotope. The mixing ratio between original and injected CO2 is calculated based on its concentration and carbon isotope. However, there is little variation in fluid samples between the wells which have seen various levels of CO2

  6. Growth and Morphology of Supercritical Fluids, a Fluid Physics Experiment Conducted on Mir, Complete

    NASA Technical Reports Server (NTRS)

    Wilkinson, R. Allen

    2001-01-01

    The Growth and Morphology of Supercritical Fluids (GMSF) is an international experiment facilitated by the NASA Glenn Research Center and under the guidance of U.S. principal investor Professor Hegseth of the University of New Orleans and three French coinvestigators: Daniel Beysens, Yves Garrabos, and Carole Chabot. The GMSF experiments were concluded in early 1999 on the Russian space station Mir. The experiments spanned the three science themes of near-critical phase separation rates, interface dynamics in near-critical boiling, and measurement of the spectrum of density fluctuation length scales very close to the critical point. The fluids used were pure CO2 or SF6. Three of the five thermostats used could adjust the sample volume with the scheduled crew time. Such a volume adjustment enabled variable sample densities around the critical density as well as pressure steps (as distinct from the usual temperature steps) applied to the sample. The French-built ALICE II facility was used for these experiments. It allows tightly thermostated (left photograph) samples (right photograph) to be controlled and viewed/measured. Its diagnostics include interferometry, shadowgraph, high-speed pressure measurements, and microscopy. Data were logged on DAT tapes, and PCMCIA cards and were returned to Earth only after the mission was over. The ground-breaking near critical boiling experiment has yielded the most results with a paper published in Physical Review Letters (ref. 1). The boiling work also received press in Science Magazine (ref. 2). This work showed that, in very compressible near-critical two-phase pure fluids, a vapor bubble was induced to temporarily overheat during a rapid heating of the sample wall. The temperature rise in the vapor was 23-percent higher than the rise in the driving container wall. The effect is due to adiabatic compression of the vapor bubble by the rapid expansion of fluid near the boundary during heatup. Thermal diffusivity is low near the

  7. Determination of Organic Partitioning Coefficients in Water-Supercritical CO2 Systems by Simultaneous in Situ UV and Near-Infrared Spectroscopies.

    PubMed

    Bryce, David A; Shao, Hongbo; Cantrell, Kirk J; Thompson, Christopher J

    2016-06-01

    CO2 injected into depleted oil or gas reservoirs for long-term storage has the potential to mobilize organic compounds and distribute them between sediments and reservoir brines. Understanding this process is important when considering health and environmental risks, but little quantitative data currently exists on the partitioning of organics between supercritical CO2 and water. In this work, a high-pressure, in situ measurement capability was developed to assess the distribution of organics between CO2 and water at conditions relevant to deep underground storage of CO2. The apparatus consists of a titanium reactor with quartz windows, near-infrared and UV spectroscopic detectors, and switching valves that facilitate quantitative injection of organic reagents into the pressurized reactor. To demonstrate the utility of the system, partitioning coefficients were determined for benzene in water/supercritical CO2 over the range 35-65 °C and approximately 25-150 bar. Density changes in the CO2 phase with increasing pressure were shown to have dramatic impacts on benzene's partitioning behavior. Our partitioning coefficients were approximately 5-15 times lower than values previously determined by ex situ techniques that are prone to sampling losses. The in situ methodology reported here could be applied to quantify the distribution behavior of a wide range of organic compounds that may be present in geologic CO2 storage scenarios. PMID:27115941

  8. Effect of debonded interfaces on corrosion of mild steel composites in supercritical CO2-saturated brines

    SciTech Connect

    John, Han; Carey, James W; Zhang, Jinsuo

    2010-10-07

    The geologic sequestration of CO{sub 2} is a proposed method to limit greenhouse gas emissions and has been the subject of many studies in the last decade. Wellbore systems achieve isolation of the storage reservoir through a combination of steel (generally carbon steel) and Portland cement. CO{sub 2} leakage along the steel-cement interface has the potential to accelerate corrosion. We conduct experiments to assess the corrosion risk at cement-steel interface under in situ wellbore conditions. Wellbore interfaces were simulated by assemblies constructed of J55 mild steel and Portland class G (Epoxy was used in this study to separate) cement and corrosion was investigated in supercritical CO{sub 2} saturated brines, (NaCl = 1 wt%) at T = 50 C, pCO{sub 2} = 1200 psi with interface gap size = 100 {micro}m and {infinity} (open surface). The experiments were carried out in a high-pressure, 1.8 L autoclave. The corrosion kinetics were measured employing electrochemical techniques including linear polarization resistance and electrochemical impedance spectroscopy techniques. The corrosion scales were analyzed using secondary electron microscopy, back scattering electron microscopy, energy dispersive spectroscopy and x-ray diffraction. Corrosion rates decreased as time with or without interface gap. In this case corrosion rates are controlled by scale protectivity through the interface gap. Scaled steel corrosion rates were two orders of magnitude less compared with fresh steel. The corrosion scale is pseudo crystalline at the open interface. Well-crystallized scale was observed at interface gap sizes 100 {micro}m. All corrosion scales were composed of iron carbonates.

  9. EVALUATION OF RESERVOIR ROCK AND WELL BORE CEMENT ALTERATION WITH SUPERCRITICAL CO2

    SciTech Connect

    William k. O'Connor; Gilbert E Rush

    2009-01-01

    An evaluation of the alteration of reservoir rock and well bore cement at their interface, under supercritical CO{sub 2} (SCCO{sub 2}), was conducted at the laboratory-scale using simulated brine solutions at down-hole conditions. These studies were intended to identify potential leakage pathways for injected CO{sub 2} due to degradation of the well bore. Two distinct test series were conducted on core samples of the Mt. Simon sandstone from the Illinois Basin, IL, and the Grand Ronde basalt from the Pasco Basin, WA. LaFarge Class H well bore cement was used for both series. Reservoir rock/cement cores were immersed within a CO{sub 2}-saturated brine for up to 2000 hours at 35 degrees C and 100 atm CO{sub 2}. Results suggest that the impact of SCCO{sub 2} injection is reservoir-specific, being highly dependent on the reservoir brine and rock type. Brine pH can be significantly altered by CO{sub 2} injection, which in turn can dramatically impact the dissolution characteristics of the reservoir rock. Finally, well bore cement alteration was identified, particularly for fresh cast cement allowed to cure at SCCO{sub 2} conditions. However, this alteration was generally limited to an outer rind of carbonate and Ca-depleted cement which appeared to protect the majority of the cement core from further attack. These studies indicate that at the cement-rock interface, the annular space may be filled by carbonate which could act as an effective barrier against further CO{sub 2} migration along the well bore.

  10. Functional properties of spice extracts obtained via supercritical fluid extraction.

    PubMed

    Leal, Patrícia F; Braga, Mara E M; Sato, Daisy N; Carvalho, João E; Marques, Marcia O M; Meireles, M Angela A

    2003-04-23

    In the present study the antioxidant, anticancer, and antimycobacterial activities of extracts from ginger (Zingiber officinale Roscoe), rosemary (Rosmarinus officinalis L.), and turmeric (Curcuma longa L.) were evaluated. The extracts were obtained using supercritical CO(2) with and without ethanol and/or isopropyl alcohol as cosolvent. The extracts' antioxidant power was assessed using the reaction between beta-carotene and linolenic acid, the antimycobacterial activity against M. tuberculosis was measured by the MABA test, and their anticancer action was tested against nine human cancer ancestries: lung, breast, breast resistant, melanoma, colon, prostate, leukemia, and kidney. The rosemary extracts exhibited the strongest antioxidant and the lowest antimycobacterial activities. Turmeric extracts showed the greatest antimycobacterial activity. Ginger and turmeric extracts showed selective anticancer activities. PMID:12696930

  11. MIXTURES OF CO2-SF6 AS WORKING FLUIDS FOR GEOTHERMAL PLANTS

    SciTech Connect

    Sabau, Adrian S; Yin, Hebi; Gruszkiewicz, Miroslaw {Mirek} S; McFarlane, Joanna; Qualls, A L; Conklin, Jim; Pawel, Steven J

    2011-01-01

    In this paper, mixtures of CO2 and SF6 were evaluated as working fluids for geothermal plants based on property measurements, molecular dynamics modeling, thermodynamic cycle analysis, and materials compatibility assessment. The CO2 - SF6 was evaluated for a reservoir temperature of 160 oC. Increasing the efficiency for these low reservoir sources will increase the options available for geothermal energy utilization in more sites across the country. The properties for the mixtures were obtained either from thermodynamic property measurements and molecular dynamics simulations. Optimum compositions of the CO2 - SF6 were identified for a well reservoir temperature and a given water-cooling condition. Concerning the global warming potential, it was estimated that the equivalent CO2 emissions per 1kWh for a Rankine cycle operating with 100% SF6 would be approximately of 7.6% than those for a coal-fired power plant.

  12. Supercritical Fluid Extraction of Plutonium and Americium from Soil

    SciTech Connect

    Fox, Robert Vincent; Mincher, Bruce Jay

    2002-08-01

    Supercritical fluid extraction (SFE) of plutonium and americium from soil was successfully demonstrated using supercritical fluid carbon dioxide solvent augmented with organophosphorus and beta-diketone complexants. Spiked Idaho soils were chemically and radiologically characterized, then extracted with supercritical fluid carbon dioxide at 2,900 psi and 65°C containing varying concentrations of tributyl phosphate (TBP) and thenoyltrifluoroacetone (TTA). A single 45 minute SFE with 2.7 mol% TBP and 3.2 mol% TTA provided as much as 88% ± 6.0 extraction of americium and 69% ± 5.0 extraction of plutonium. Use of 5.3 mol% TBP with 6.8 mol% of the more acidic beta-diketone hexafluoroacetylacetone (HFA) provided 95% ± 3.0 extraction of americium and 83% ± 5.0 extraction of plutonium in a single 45 minute SFE at 3,750 psi and 95°C. Sequential chemical extraction techniques were used to chemically characterize soil partitioning of plutonium and americium in pre-SFE soil samples. Sequential chemical extraction techniques demonstrated that spiked plutonium resides primarily (76.6%) in the sesquioxide fraction with minor amounts being absorbed by the oxidizable fraction (10.6%) and residual fractions (12.8%). Post-SFE soils subjected to sequential chemical extraction characterization demonstrated that 97% of the oxidizable, 78% of the sesquioxide and 80% of the residual plutonium could be removed using SFE. These preliminary results show that SFE may be an effective solvent extraction technique for removal of actinide contaminants from soil.

  13. CO2- and Ca-rich Fluids Drive Dolomite Formation During Hydrothermal Alteration of Peridotite

    NASA Astrophysics Data System (ADS)

    Grozeva, N. G.; Klein, F.; Seewald, J.; Sylva, S.

    2014-12-01

    We present an experimental study investigating reaction pathways during the interaction of CO2-rich aqueous fluids with mantle peridotite, which have major implications for geochemical budgets and microbial life in oceanic lithosphere. Powdered harzburgite was reacted with a Ca-enriched fluid in a flexible-cell hydrothermal apparatus at 300°C and 35 MPa for 1.7 years. A CO2-rich fluid was subsequently injected and allowed to react for 8 months to examine the formation of carbonates under reducing conditions. Fluids were sampled throughout the experiment to monitor changes in fluid chemistry, and the secondary mineralogy was analyzed at the end of the experiment. Fluid speciation and mineral analyses suggest that initial serpentinization of harzburgite led to the precipitation of serpentine, brucite, magnetite, chlorite, calcite and Ni-sulfides. Fluids during this stage were characterized by low concentrations of dissolved Si, Mg and CO2, alkaline pH(25°C), and high concentrations of dissolved Ca, consistent with buffering by serpentine-brucite-diopside-calcite equilibria. H2(aq) concentrations increased during the first 10 months of reaction (due to magnetite formation), but subsequently plateaued, suggesting that serpentinization approached completion prior to CO2 injection. The introduction of CO2 resulted in acidic pH(25°C), substantial decreases in H2(aq) concentrations, and increases in dissolved SiO2 and Mg2+ concentrations. Dolomite and high-Mg calcite appear to have formed at the expense of olivine, calcite and likely brucite. However, petrographic observations suggest that Mg-calcite was only a transient phase and was ultimately destabilized in favor of dolomite. Replacement textures with carbonate in mesh centers are strikingly similar to those found in dolomite-altered abyssal serpentinites from the Atlantis Massif. While magnesite precipitation seems possible in ridge environments, high CO2(aq) and Ca2+ activities in serpentinization systems appear

  14. Immiscible fluids (CO 2-brines) in optical fluorite, Nordvik-Taimyr, Russia

    NASA Astrophysics Data System (ADS)

    Prokof'ev, Vsevolod Y.; Baksheev, Ivan A.; Korytov, Feodor Y.; Touret, Jacques

    2006-07-01

    Fluid inclusion investigations in optical fluorite from the Nordvik salt dome caprock (Khatanga Gulf, Taimyr Peninsula, Russia) show that the fluorite has been formed at a temperature of about 300 °C, from CO 2-brine immiscible hydrothermal fluids. Unmixing occurred at a depth of several kilometres, resulting in the liberation of dense CO 2-rich fluids, which played a significant role in helping the diapir to reach its intrusive character. Compared to other optical fluorite deposits in Russia, the exceptional quality of the Nordvik occurrence is due to a relatively high formation temperature, as well as a high salinity (30-35 wt% NaCl eq.) of hydrothermal aqueous fluids. To cite this article: V.Y. Prokof'ev et al., C. R. Geoscience 338 (2006).

  15. Accurate on-line mass flow measurements in supercritical fluid chromatography.

    PubMed

    Tarafder, Abhijit; Vajda, Péter; Guiochon, Georges

    2013-12-13

    This work demonstrates the possible advantages and the challenges of accurate on-line measurements of the CO2 mass flow rate during supercritical fluid chromatography (SFC) operations. Only the mass flow rate is constant along the column in SFC. The volume flow rate is not. The critical importance of accurate measurements of mass flow rates for the achievement of reproducible data and the serious difficulties encountered in supercritical fluid chromatography for its assessment were discussed earlier based on the physical properties of carbon dioxide. In this report, we experimentally demonstrate the problems encountered when performing mass flow rate measurements and the gain that can possibly be achieved by acquiring reproducible data using a Coriolis flow meter. The results obtained show how the use of a highly accurate mass flow meter permits, besides the determination of accurate values of the mass flow rate, a systematic, constant diagnosis of the correct operation of the instrument and the monitoring of the condition of the carbon dioxide pump. PMID:24210558

  16. Supercritical fluid extracts of rosemary leaves exhibit potent anti-inflammation and anti-tumor effects.

    PubMed

    Peng, Chiung-Huei; Su, Jeng-De; Chyau, Charng-Cherng; Sung, Tzu-Ying; Ho, Shin-Shien; Peng, Chiung-Chi; Peng, Robert Y

    2007-09-01

    Supercritical fluid SF-CO2 treatment of Rosemarinus officinalis L. fresh leaves under optimum conditions (80 degrees C at 5,000 psi) yielded 5.3% of extract supercritical fluid extraction (SFE)-80, in which five major active principles were identified by liquid chromatography/mass spectrometry (LC/MS), viz., rosmarinic acid, carnosol, 12-methoxycarnosic acid, carnosic acid, and methyl carnosate. Total phenolic content was 155.8 mg/ gallic acid equivalent (GAE)/g in SFE-80, which showed 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging of 81.86% at 0.01 mg/ml. When treated in RAW 264.7, apparent dose-dependent NO inhibition occurred at dosages of 1.56 to 6.25 microg/ml, and more drastically at 12.5 and 25 microg/ml. At 0.5 to 5.0 microg/ml, SFE-80 exhibited dose-dependent viability suppression and significant tumor necrosis factor alpha (TNF-alpha) production in Hep 3B, whereas no effect was found in Chang liver cells. Furthermore, no effect was observed in RAW 264.7 at dosages of 3.13 to 25 microg/ml, indicating that SFE-80 exhibited a noncytotoxic character. Conclusively, rosemary can be considered an herbal anti-inflammatory and anti-tumor agent. PMID:17827696

  17. Computational Fluid Dynamics Analysis of Canadian Supercritical Water Reactor (SCWR)

    NASA Astrophysics Data System (ADS)

    Movassat, Mohammad; Bailey, Joanne; Yetisir, Metin

    2015-11-01

    A Computational Fluid Dynamics (CFD) simulation was performed on the proposed design for the Canadian SuperCritical Water Reactor (SCWR). The proposed Canadian SCWR is a 1200 MW(e) supercritical light-water cooled nuclear reactor with pressurized fuel channels. The reactor concept uses an inlet plenum that all fuel channels are attached to and an outlet header nested inside the inlet plenum. The coolant enters the inlet plenum at 350 C and exits the outlet header at 625 C. The operating pressure is approximately 26 MPa. The high pressure and high temperature outlet conditions result in a higher electric conversion efficiency as compared to existing light water reactors. In this work, CFD simulations were performed to model fluid flow and heat transfer in the inlet plenum, outlet header, and various parts of the fuel assembly. The ANSYS Fluent solver was used for simulations. Results showed that mass flow rate distribution in fuel channels varies radially and the inner channels achieve higher outlet temperatures. At the outlet header, zones with rotational flow were formed as the fluid from 336 fuel channels merged. Results also suggested that insulation of the outlet header should be considered to reduce the thermal stresses caused by the large temperature gradients.

  18. Supercritical fluid extraction of aflatoxin B(1) from soil.

    PubMed

    Starr, James M; Selim, Mustafa I

    2008-10-31

    This research describes the development of a supercritical fluid extraction (SFE) method to recover aflatoxin B(1) from fortified soil. The effects of temperature, pressure, modifier (identity and percentage), and extraction type were assessed. Using the optimized SFE conditions, the mean recovery from air dried soil was 72%. The variables associated with changes in recovery of aflatoxin were co-solvents, static extraction, and temperature. Acetonitrile-2% acetic acid, used both in-cell and on-line, provided the most efficient recovery. The results indicate that desorption from the soil was the limiting factor in recovery and that the static phase was more important than the dynamic. PMID:18814879

  19. Hydroetching of high surface area ceramics using moist supercritical fluids

    DOEpatents

    Fryxell, Glen; Zemanian, Thomas S.

    2004-11-02

    Aerogels having a high density of hydroxyl groups and a more uniform pore size with fewer bottlenecks are described. The aerogel is exposed to a mixture of a supercritical fluid and water, whereupon the aerogel forms a high density of hydroxyl groups. The process also relaxes the aerogel into a more open uniform internal structure, in a process referred to as hydroetching. The hydroetching process removes bottlenecks from the aerogels, and forms the hydrogels into more standard pore sizes while preserving their high surface area.

  20. Separations of petroleum products involving supercritical fluid chromatography.

    PubMed

    Thiébaut, Didier

    2012-08-24

    This paper gives a survey of the most attractive trends and applications of supercritical fluid chromatography in the petroleum industry: simulated distillation, group-type analysis and related applications including the implementation of multidetection in a so-called "hypernated" system, as well as the hyphenation to GC×GC for improved group-type separation, SFC×GC and first promising SFC×SFC results. Some specific technical information related to the use of capillary columns or conventional packed columns in combination with FID (or detectors that require decompression and in some instances splitting of the mobile phase prior detection) is also provided. PMID:22818737

  1. Genomic insights into growth and survival of supercritical-CO2 tolerant bacterium MIT0214 under conditions associated with geologic carbon dioxide sequestration

    NASA Astrophysics Data System (ADS)

    Peet, K. C.; Freedman, A. J.; Hernandez, H.; Thompson, J. R.

    2011-12-01

    Carbon capture and storage (CCS) of CO2 has the potential to significantly reduce the emissions of greenhouse gasses associated with fossil fuel combustion. The largest potential for storing captured CO2 in the United Sates is in deep geologic saline formations. Currently, little is known about the effects of CO2 storage on biologically active microbial communities found in the deep earth biosphere. Therefore, to investigate how deep earth microbial communities will be affected by the storage of CO2 we have enriched for a microbial consortium from the saline formation waters of the Frio 2 project site (Texas Gulf Coast) that is capable of growth in nutrient media under a supercritical CO2 headspace (Hernandez, et al). The cultivation of actively growing cells in an environment containing scCO2 is unexpected based on previous experimental evidence of microbial sterilization attributed to the acidic, desiccating, and solvent-like properties of scCO2. We have isolated strain MIT0214 from this supercritical CO2 based enrichment and have sequenced its genome using the Illumina platform followed by de novo assembly of reads and targeted Sanger sequencing to reduce gaps in the draft assembly. The genome of strain MIT0214 is approximately 5,551,062 base pairs with 35% GC-content and is most similar to nonpathogenic Bacillus cereus strain ATCC 14597. Annotation of the draft assembly of the MIT0214 genome by the Rapid Annotation using Subsystem Technology (RAST) server revealed 5538 coding sequences where 4145 of the coding sequences were assigned putative functions. These functions were enriched in cell wall and capsule formation, phage/prophage and plasmids, gene regulation and signaling, and nitrogen and sulfur metabolism relative to the genome of the most closely-related surface-isolated B. cereus reference (ATCC 14597) and in total 773,416 bp of the MIT0214 genome content was distinct from the B. cereus reference. Notably, this set of distinct sequences were most

  2. Varying rock responses as an indicator of changes in CO2-H2O fluid composition

    NASA Technical Reports Server (NTRS)

    Friend, C. R. L.

    1986-01-01

    The formation of the late Archean charnockite zone of southern India was ascribed to dehydration recrystallization due to an influx of CO2. Pressure temperature conditions for the metamorphism were calculated at about 750 C and 7.5 Kbar. The composition of the volatile species presently contained in fluid inclusions in the rocks changes across the transition zone. The transition zone was studied at Kabbaldurga and the paths taken by the fluids were identified.

  3. Effect of ultrasound on the supercritical CO2 extraction of bioactive compounds from dedo de moça pepper (Capsicum baccatum L. var. pendulum).

    PubMed

    Dias, Arthur Luiz Baião; Arroio Sergio, Camilla Scarelli; Santos, Philipe; Barbero, Gerardo Fernandéz; Rezende, Camila Alves; Martínez, Julian

    2016-07-01

    Extracts with bioactive compounds were obtained from the red pepper variety "dedo de moça" (Capsicum baccatum L. var. pendulum) through supercritical fluid extraction with carbon dioxide assisted by ultrasound (SFE-US). The process was tested at pressures of 15, 20 and 25 MPa; temperatures of 40, 50 and 60 °C, and ultrasonic powers of 200, 400 and 600 W applied during 40, 60 and 80 min of extraction. The CO2 mass flow rate was fixed at 1.7569 × 10(-4) kg/s. Global yield, phenolic content, antioxidant capacity and capsaicinoid concentration were evaluated in the extracts. The application of ultrasound raised the global extraction yield of SFE up to 45%. The phenolic content of the extract increased with the application of higher ultrasound power and radiation time. The capsaicinoid yield was also enhanced with ultrasound up to 12%. However, the antioxidant capacity did not increase with the ultrasound application. The BET-based model and the broken and intact cell model fitted well to the kinetic SFE curves. The BET-based model with three adjustable parameters resulted in the best fits to the experimental data. Field emission scanning electron microscopy (FESEM) images showed that SFE disturbed the vegetable matrix, releasing particles from the inner region of the plant cells to their surface. When the ultrasound was applied this effect was more pronounced. On the other hand, cracks, fissures or any sign of rupture were not identified on the sample surface. PMID:26964951

  4. Experimental study on supercritical CO2 adsorption on coals from Upper Silesian coal Basin

    NASA Astrophysics Data System (ADS)

    Weishauptová, Zuzana; Přibyl, Oldřich; Sýkorová, Ivana

    2014-05-01

    Although coal seams, besides saline aquifers and depleted oil and gas reservoirs, have the lowest capacity for deposition of carbon dioxide yet this relatively new technology is considered advantageous from an economical standpoint, especially in the case of location of a repository in the vicinity of a power plant producing carbon dioxide. Another appreciable positive aspect is injection of carbon dioxide into unmineable methane-bearing seams, which simultaneously increases production of coal methane as a valuable energetic resource. Suitability of coal seams as carbon dioxide repositories is given by exceptional properties of coal, which during the coalification process retained in its interior spatial arrangement a substantial part of the porous structure of the original plant material with predominance of cavities of an effective size < 2nm. The major mechanism of the storage is represented by sorption processes taking place in the coal porous system. The effectivity of the sorption process depends on properties of the coal matter, seam environment, and carbon dioxide under the conditions corresponding to the situation in situ. Among the basic parameters for selection of a suitable repository based on simulation of the deposition process there is determination of its sorption capacity. The capacity can be determined in a laboratory by measuring the amount of carbon dioxide captured in a coal sample at a pressure and temperature corresponding to supercritical conditions in situ using high pressure sorption techniques. Similarly, the amount of methane bound in coal is based on high pressure measurement of it sorbed amount The present study has been aimed at investigation of the effect of the coal properties on the carbon dioxide and methane sorption capacities. High pressure sorption experiments with carbon dioxide and methane were carried out at the temperature 45 oC and the pressure up to 15 MPa with three samples of methane-bearing, medium rank coals in a

  5. Supercritical fluid reactions for coal processing. Quarterly report, July 1--September 30, 1996

    SciTech Connect

    Eckert, C.A.

    1996-12-31

    Exciting opportunities exist for the application of supercritical fluid (SCF) reactions for the pre-treatment of coal. Utilizing reactants which resemble the organic nitrogen containing components of coal, we propose to develop a method to tailor chemical reactions in supercritical fluid solvents for the specific application of coal denitrogenation. The Diels-Alder reaction of anthracene and 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) was chosen as the model system and was investigated in supercritical carbon dioxide.

  6. Capillary pressure-saturation relations for supercritical CO2 and brine in limestone/dolomite sands: implications for geologic carbon sequestration in carbonate reservoirs.

    PubMed

    Wang, Shibo; Tokunaga, Tetsu K

    2015-06-16

    In geologic carbon sequestration, capillary pressure (Pc)-saturation (Sw) relations are needed to predict reservoir processes. Capillarity and its hysteresis have been extensively studied in oil-water and gas-water systems, but few measurements have been reported for supercritical (sc) CO2-water. Here, Pc-Sw relations of scCO2 displacing brine (drainage), and brine rewetting (imbibition) were studied to understand CO2 transport and trapping behavior under reservoir conditions. Hysteretic drainage and imbibition Pc-Sw curves were measured in limestone sands at 45 °C under elevated pressures (8.5 and 12.0 MPa) for scCO2-brine, and in limestone and dolomite sands at 23 °C (0.1 MPa) for air-brine using a new computer programmed porous plate apparatus. scCO2-brine drainage and imbibition curves shifted to lower Pc relative to predictions based on interfacial tension, and therefore deviated from capillary scaling predictions for hydrophilic interactions. Fitting universal scaled drainage and imbibition curves show that wettability alteration resulted from scCO2 exposure over the course of months-long experiments. Residual trapping of the nonwetting phases was determined at Pc = 0 during imbibition. Amounts of trapped scCO2 were significantly larger than for those for air, and increased with pressure (depth), initial scCO2 saturation, and time. These results have important implications for scCO2 distribution, trapping, and leakage potential. PMID:25945400

  7. Optimization of supercritical fluid extraction by carbon dioxide with organic modifiers of polycyclic aromatic hydrocarbons from urban particulate matter.

    PubMed

    Librando, Vito; Tomaselli, Gaetano; Tringali, Giuseppe

    2005-01-01

    The main advantages of using supercritical fluids for the extractions of organic pollutants from environmental matrix is that they are inexpensive, contaminant free, and less costly to dispose safely than organic solvents. In this work, a series of extraction experiments were carried out using CO2 as supercritical fluid on a certified sample of "Urban dust" (NIST S.R.M. 1649a) to optimize the analytical parameters with the aim of investigating the extraction limit of organic pollutant by using an almost "organic solvent-free" technique. The certified sample contains small concentrations of several organic pollutants, as PAH and PCB. The initial tests of extraction were carried out with only CO2 in supercritical phase, by maintaining the temperature at 50 degrees C and 80 degrees C and by making the pressure vary between 230 bar and 600 bar. The effect of three organic modifiers (methanol, n-hexane and toluene), added at 5% in volume, has been considered. The yield of recovery has been estimated for anthracene, fluoranthene, chrysene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene by GC-MS according to the increasing molecular weight. PMID:16485662

  8. Antioxidant effect of supercritical CO2 extracted Nigella sativa L. seed extract on deep fried oil quality parameters.

    PubMed

    Solati, Zeinab; Baharin, Badlishah Sham

    2015-06-01

    Effect of supercritical CO2 extracted Nigella sativa L. seed extract (NE) on frying performance of sunflower oil and refined, bleached and deodorized (RBD) palm olein was investigated at concentrations of 1.2 % and 1.0 % respectively. Two frying systems containing 0 % N. sativa L. extract (Control) and 0.02 % butylated hydroxytoluene (BHT) were used for comparison. Physicochemical properties such as fatty acid composition (FAC), Peroxide Value (PV), Anisidine Value (AV), Totox Value (TV), Total Polar Content (TPC), C18:2/C16:0 ratio and viscosity of frying oils were determined during five consecutive days of frying. Results have shown that N. sativa L. extract was able to improve the oxidative stability of both frying oils during the frying process compared to control. The stabilizing effect of antioxidants were in the order of BHT > NE. RBD palm olein was found to be more stable than sunflower oil based on the ratio of linoleic acid (C18:2) to palmitic acid (C16:0) and fatty acid composition. PMID:26028729

  9. Evaluation of Anticancer and Antioxidant Activity of a Commercially Available CO2 Supercritical Extract of Old Man's Beard (Usnea barbata).

    PubMed

    Zugic, Ana; Jeremic, Ivica; Isakovic, Aleksandra; Arsic, Ivana; Savic, Snezana; Tadic, Vanja

    2016-01-01

    There is a worldwide ongoing investigation for novel natural constituents with cytotoxic and antioxidant properties. The aim of this study was to investigate chemical profile and stated biological activities of the supercritical CO2 extract (SCE) of old man's beard compared to the extracts obtained using the conventional techniques (Soxhlet extracts and macerate). The most abundant compound identified was usnic acid, which content was inversely proportional to the polarity of the solvent used and was the highest in the SCE, which was the sample revealing the highest cytotoxic activity in tested tumor cell lines (B16 mouse melanoma and C6 rat glioma), with lower IC50 values compared to pure usnic acid. Further investigations suggested both SCE and usnic acid to induce apoptosis and/or autophagy in B16 and C6, indicating higher cytotoxicity of SCE to be related to the higher degree of ROS production. A good correlation of usnic acid content in the extracts and their antioxidant capacity was established, extricating SCE as the most active one. Presented results support further investigations of SCE of old man's beard as a prospective therapeutic agent with potential relevance in the treatment of cancer and/or in oxidative stress-mediated conditions. PMID:26745885

  10. Impact of solvents and supercritical CO2 drying on the morphology and structure of polymer-based biofilms

    NASA Astrophysics Data System (ADS)

    Causa, Andrea; Salerno, Aurelio; Domingo, Concepción; Acierno, Domenico; Filippone, Giovanni

    2014-05-01

    In the present work, two-dimensional systems based on biodegradable polymers such as poly(ɛ-caprolactone) (PCL), poly(ethylene oxide) (PEO) and polylactic acid (PLA) are fabricated by means of a sustainable approach which consists in inducing phase separation in solutions of such polymers and "green" solvents, namely ethyl lactate (EL) and ethyl acetate (EA). The extraction of the solvent is promoted by a controlled drying process, which is performed in either air or supercritical CO2. The latter can indeed act as both an antisolvent, which favors the deposition of the polymer by forming a mixture with EL and EA, and a plasticizing agent, whose solvation and transport properties may considerably affect the microstructure and crystallinity of the polymer films. The morphological, topographical and crystalline properties of the films are tailored through a judicial selection of the materials and the processing conditions and assessed by means of thermal analyses, polarized optical microscopy, scanning electron microscopy and confocal interferometric microscopy. The results show that the morphological and crystalline properties of the films are strongly dependent on the choice of both the polymer/solvent system and the operating conditions during the drying step. In particular, the morphological, topographical and thermal properties of films prepared starting from highly crystalline polymers, namely PCL and PEO, are greatly affected by the crystallization of the material. Conversely, the less crystalline PLA forms almost completely amorphous films.

  11. [Single-pump on-line addition of modifier for supercritical fluid chromatography].

    PubMed

    Lu, F; Liu, L L; Li, L; Zhai, Z X; Wu, Y T

    1999-11-01

    Modified CO2 as mobile phase is usually necessary for packed-column supercritical fluid chromatography. Single syringe pump was applied in this work to add modifier through a parallel connection device, which can maintain constant and stable volume fraction of modifier without any contamination of the pump. Viscosity of the modifiers (here are methanol and acetone) and the length of the CO2 pipe line/modifier pipe line can affect the volume fraction. Volume fractions of methanol and acetone were determined by gas chromatography and ultraviolet spectrometry respectively and their rules of variation were also examined. It shows that the volume fraction of methanol is lower than that of acetone under similar condition. With fixed modifierr line, the longer the CO2 line is, the higher the volume fraction will be. The new device can conveniently alter the nature and ratio of the modifier with quite stable volume fraction. The online addition device can tentatively replace the dual-pump system. PMID:12552698

  12. Direct coupling of packed column supercritical fluid chromatography to continuous corona discharge ion mobility spectrometry.

    PubMed

    Rahmanian, A; Ghaziaskar, H S; Khayamian, T

    2013-01-11

    In this study, packed column supercritical fluid chromatography (SFC) was directly coupled to a continuous corona discharge (CD) ion mobility spectrometer (IMS) with several modifications. The main advantage of the developed detector is its capability to introduce full column effluent up to 2000 mL min(-1) CO(2) gas directly into the IMS cell relative to 40 mL min(-1) CO(2) gas as a maximum tolerance, reported for the previous IMS detectors. This achievement was made possible because of using corona discharge instead of (63)Ni as an ionization source and locating the inlet and outlet of the CO(2) gas in the counter electrode of the CD in opposite direction. In addition, a heated interface was placed between back pressure regulator (BPR) and the IMS cell to heat the output of the BPR for introducing sample as the gas phase into the IMS cell. Furthermore, a make-up methanol flow was introduced between the column outlet and BPR to provide a more uniform flow through the BPR and also to prevent freezing and deposition of the analytes in the BPR. The performance of the SFC-CD-IMS was evaluated by analysis of testosterone, medroxyprogesterone, caffeine, and theophylline as test compounds and figures of merit for these compounds have been calculated. PMID:23261285

  13. Separation of supercritical slab-fluids to form aqueous fluid and melt components in subduction zone magmatism

    PubMed Central

    Kawamoto, Tatsuhiko; Kanzaki, Masami; Mibe, Kenji; Ono, Shigeaki

    2012-01-01

    Subduction-zone magmatism is triggered by the addition of H2O-rich slab-derived components: aqueous fluid, hydrous partial melts, or supercritical fluids from the subducting slab. Geochemical analyses of island arc basalts suggest two slab-derived signatures of a melt and a fluid. These two liquids unite to a supercritical fluid under pressure and temperature conditions beyond a critical endpoint. We ascertain critical endpoints between aqueous fluids and sediment or high-Mg andesite (HMA) melts located, respectively, at 83-km and 92-km depths by using an in situ observation technique. These depths are within the mantle wedge underlying volcanic fronts, which are formed 90 to 200 km above subducting slabs. These data suggest that sediment-derived supercritical fluids, which are fed to the mantle wedge from the subducting slab, react with mantle peridotite to form HMA supercritical fluids. Such HMA supercritical fluids separate into aqueous fluids and HMA melts at 92 km depth during ascent. The aqueous fluids are fluxed into the asthenospheric mantle to form arc basalts, which are locally associated with HMAs in hot subduction zones. The separated HMA melts retain their composition in limited equilibrium with the surrounding mantle. Alternatively, they equilibrate with the surrounding mantle and change the major element chemistry to basaltic composition. However, trace element signatures of sediment-derived supercritical fluids remain more in the melt-derived magma than in the fluid-induced magma, which inherits only fluid-mobile elements from the sediment-derived supercritical fluids. Separation of slab-derived supercritical fluids into melts and aqueous fluids can elucidate the two slab-derived components observed in subduction zone magma chemistry. PMID:23112158

  14. Separation of supercritical slab-fluids to form aqueous fluid and melt components in subduction zone magmatism.

    PubMed

    Kawamoto, Tatsuhiko; Kanzaki, Masami; Mibe, Kenji; Matsukage, Kyoko N; Ono, Shigeaki

    2012-11-13

    Subduction-zone magmatism is triggered by the addition of H(2)O-rich slab-derived components: aqueous fluid, hydrous partial melts, or supercritical fluids from the subducting slab. Geochemical analyses of island arc basalts suggest two slab-derived signatures of a melt and a fluid. These two liquids unite to a supercritical fluid under pressure and temperature conditions beyond a critical endpoint. We ascertain critical endpoints between aqueous fluids and sediment or high-Mg andesite (HMA) melts located, respectively, at 83-km and 92-km depths by using an in situ observation technique. These depths are within the mantle wedge underlying volcanic fronts, which are formed 90 to 200 km above subducting slabs. These data suggest that sediment-derived supercritical fluids, which are fed to the mantle wedge from the subducting slab, react with mantle peridotite to form HMA supercritical fluids. Such HMA supercritical fluids separate into aqueous fluids and HMA melts at 92 km depth during ascent. The aqueous fluids are fluxed into the asthenospheric mantle to form arc basalts, which are locally associated with HMAs in hot subduction zones. The separated HMA melts retain their composition in limited equilibrium with the surrounding mantle. Alternatively, they equilibrate with the surrounding mantle and change the major element chemistry to basaltic composition. However, trace element signatures of sediment-derived supercritical fluids remain more in the melt-derived magma than in the fluid-induced magma, which inherits only fluid-mobile elements from the sediment-derived supercritical fluids. Separation of slab-derived supercritical fluids into melts and aqueous fluids can elucidate the two slab-derived components observed in subduction zone magma chemistry. PMID:23112158

  15. Modeling of CO2 solubility in single and mixed electrolyte solutions using statistical associating fluid theory

    NASA Astrophysics Data System (ADS)

    Jiang, Hao; Panagiotopoulos, Athanassios Z.; Economou, Ioannis G.

    2016-03-01

    Statistical associating fluid theory (SAFT) is used to model CO2 solubilities in single and mixed electrolyte solutions. The proposed SAFT model implements an improved mean spherical approximation in the primitive model to represent the electrostatic interactions between ions, using a parameter K to correct the excess energies ("KMSA" for short). With the KMSA formalism, the proposed model is able to describe accurately mean ionic activity coefficients and liquid densities of electrolyte solutions including Na+, K+, Ca2+, Mg2+, Cl-, Br- and SO42- from 298.15 K to 473.15 K using mostly temperature independent parameters, with sole exception being the volume of anions. CO2 is modeled as a non-associating molecule, and temperature-dependent CO2-H2O and CO2-ion cross interactions are used to obtain CO2 solubilities in H2O and in single ion electrolyte solutions. Without any additional fitting parameters, CO2 solubilities in mixed electrolyte solutions and synthetic brines are predicted, in good agreement with experimental measurements.

  16. On the production behavior of enhanced geothermal systems with CO2as working fluid

    SciTech Connect

    Pruess, K.

    2007-05-31

    Numerical simulation is used to evaluate mass flow and heatextraction rates from enhanced geothermal injection-production systemsthat are operated using either CO2 or water as heat transmission fluid.For a model system patterned after the European hot dry rock experimentat Soultz, we find significantly greater heat extraction rates for CO2 ascompared to water. The strong dependence of CO2 mobility (=density/viscosity) upon temperature and pressure may lead to unusualproduction behavior, where heat extraction rates can actually increasefor a time, even as the reservoir is subject to thermal depletion. Wepresent the first-ever three-dimensional simulations of CO2injection-production systems. These show strong effects of gravity onmass flow and heat extraction, due to the large contrast of CO2 densitybetween cold injection and hot production conditions. The tendency forpreferential flow of cold, dense CO2 along the reservoir bottom can leadto premature thermal breakthrough. The problem can be avoided byproducing from only a limited depth interval at the top of thereservoir.

  17. A Fundamental Study of Convective Mixing of CO2 in Layered Heterogeneous Saline Aquifers with Low Permeability Zones using Surrogate Fluids and Numerical Modeling

    NASA Astrophysics Data System (ADS)

    Agartan, E.; Illangasekare, T. H.; Cihan, A.; Birkholzer, J. T.; Zhou, Q.; Trevisan, L.

    2013-12-01

    Dissolution trapping is one of the primary mechanisms contributing to long-term and stable storage of supercritical CO2 (scCO2) in deep saline geologic formations. When entrapped scCO2 dissolves in formation brine, density-driven convective fingers are expected to be generated due to the higher density of the solution compared to brine. These fingers enhance mixing of dissolved scCO2 in brine (Ennis-King & Paterson, 2003). The goal of this study is to evaluate the contribution of convective mixing to dissolution trapping of CO2 in naturally layered heterogeneous formations with low permeability zones via experimental and numerical analyses. To understand the fundamental process of dissolution trapping in the laboratory under ambient pressure and temperature conditions, a group of surrogate fluids were selected according to their density and viscosity values before and after dissolution. Fluids were tested in a variety of porous media systems. After selection of the appropriate fluid mixture based on the closest behavior to scCO2 brine systems, a set of experiments in a small homogeneously packed test tank was performed to analyze the fingering behaviors. A second set of experiments was conducted in the same test tank with layered soil systems to study the effects of formation heterogeneity on convective mixing. A finite volume method based numerical code was developed to capture the dominant processes observed in the experiments. This model was then used to simulate more complex heterogeneous systems that were not represented in the limited set of experiments. Results of these analyses suggest that convective fingers developed in homogeneous formations may not be significantly contributing to mixing and hence dissolution trapping in heterogeneous formations depending on the permeability contrasts and thickness of the low permeability layers.

  18. Prospects of Supercritical Fluids in Realizing Graphene-Based Functional Materials.

    PubMed

    Padmajan Sasikala, Suchithra; Poulin, Philippe; Aymonier, Cyril

    2016-04-01

    Supercritical-fluids science and technology predate all the approaches that are currently established for graphene production by several decades in advanced materials design. However, it has only recently been proposed as a plausible approach for graphene processing. Since then, supercritical fluids have emerged into contention as an alternative to existing technologies because of their scalability and versatility in processing graphene materials, which include composites, aerogels, and foams. Here, an overview is presented of such materials prepared through supercritical fluids from an advanced materials science standpoint, with a discussion on their fundamental properties and technological applications. The benefits of supercritical-fluid processing over conventional liquid-phase processing are presented. The benefits include not only better performances for advanced applications but also environmental issues associated with the synthesis process. Nevertheless, the limitations of supercritical-fluid processing are also stressed, along with challenges that are still faced toward the achievement of the great expectations from graphene materials. PMID:26879938

  19. Complex fluid flow revealed by monitoring CO2 injection in a fluvial formation

    NASA Astrophysics Data System (ADS)

    Lu, Jiemin; Cook, Paul J.; Hosseini, Seyyed A.; Yang, Changbing; Romanak, Katherine D.; Zhang, Tongwei; Freifeld, Barry M.; Smyth, Rebecca C.; Zeng, Hongliu; Hovorka, Susan D.

    2012-03-01

    At Cranfield, Mississippi, United States, a large-scale carbon dioxide (CO2) injection through an injection well (˜3,080 m deep) was continuously monitored using U-tube samplers in two observation wells located 68 and 112 m east of the injector. The Lower Tuscaloosa Formation injection zone, which consists of amalgamated fluvial point-bar and channel-fill deposits, presents an interesting environment for studying fluid flow in heterogeneous formations. Continual fluid sampling was carried out during the first month of CO2 injection. Two subsequent tracer tests using sulfur hexafluoride (SF6) and krypton were conducted at different injection rates to measure flow velocity change. The field observations showed significant heterogeneity of fluid flow and for the first time clearly demonstrated that fluid flow evolved with time and injection rate. It was found the wells were connected through numerous, separate flow pathways. CO2 flowed through an increasing fraction of the reservoir and sweep efficiency improved with time. The field study also first documented in situ component exchange between brine and gas phases during CO2 injection. It was found that CH4 degassed from brine and is enriched along the gas-water contact. Multiple injectate flow fronts with high CH4 concentration arrived at different times and led to gas composition fluctuations in the observation wells. The findings provide valuable insights into heterogeneous multiphase flow in rock formations and show that conventional geological models and static fluid flow simulations are unable to fully describe the heterogeneous and dynamic flow during fluid injection.

  20. An H2O-CO2 mixed fluid saturation model compatible with rhyolite-MELTS

    NASA Astrophysics Data System (ADS)

    Ghiorso, Mark S.; Gualda, Guilherme A. R.

    2015-06-01

    A thermodynamic model for estimating the saturation conditions of H2O-CO2 mixed fluids in multicomponent silicate liquids is described. The model extends the capabilities of rhyolite-MELTS (Gualda et al. in J Petrol 53:875-890, 2012a) and augments the water saturation model in MELTS (Ghiorso and Sack in Contrib Mineral Petrol 119:197-212, 1995). The model is internally consistent with the fluid-phase thermodynamic model of Duan and Zhang (Geochim Cosmochim Acta 70:2311-2324, 2006). It may be used independently of rhyolite-MELTS to estimate intensive variables and fluid saturation conditions from glass inclusions trapped in phenocrysts. The model is calibrated from published experimental data on water and carbon dioxide solubility, and mixed fluid saturation in silicate liquids. The model is constructed on the assumption that water dissolves to form a hydroxyl melt species, and that carbon dioxide both a molecular species and a carbonate ion, the latter complexed with calcium. Excess enthalpy interaction terms in part compensate for these simplistic assumptions regarding speciation. The model is restricted to natural composition liquids over the pressure range 0-3 GPa. One characteristic of the model is that fluid saturation isobars at pressures greater than ~100 MPa always display a maximum in melt CO2 at nonzero H2O melt concentrations, regardless of bulk composition. This feature is universal and can be attributed to the dominance of hydroxyl speciation at low water concentrations. The model is applied to four examples. The first involves estimation of pressures from H2O-CO2-bearing glass inclusions found in quartz phenocrysts of the Bishop Tuff. The second illustrates H2O and CO2 partitioning between melt and fluid during fluid-saturated equilibrium and fractional crystallization of MORB. The third example demonstrates that the position of the quartz-feldspar cotectic surface is insensitive to melt CO2 contents, which facilitates geobarometry using phase

  1. Intramolecular vibrational energy redistribution and intermolecular energy transfer of benzene in supercritical CO 2: measurements from the gas phase up to liquid densities

    NASA Astrophysics Data System (ADS)

    von Benten, R.; Charvat, A.; Link, O.; Abel, B.; Schwarzer, D.

    2004-03-01

    Femtosecond pump probe spectroscopy was employed to measure intramolecular vibrational energy redistribution (IVR) and intermolecular vibrational energy transfer (VET) of benzene in the gas phase and in supercritical (sc) CO 2. We observe two IVR time scales the faster of which proceeds within τ IVR(1)<0.5 ps. The slower IVR component has a time constant of τ IVR(2)=(48±5) ps in the gas phase and in scCO 2 is accelerated by interactions with the solvent. At the highest CO 2 density it is reduced to τ IVR(2)=(6±1) ps. The corresponding IVR rate constants show a similar density dependence as the VET rate constants. Model calculations suggest that both quantities correlate with the local CO 2 density in the immediate surrounding of the benzene molecule.

  2. Antiageing Mechanisms of a Standardized Supercritical CO2 Preparation of Black Jack (Bidens pilosa L.) in Human Fibroblasts and Skin Fragments

    PubMed Central

    Dieamant, Gustavo; Pereda, Maria Del Carmen V.; Nogueira, Cecília; Eberlin, Samara; Facchini, Gustavo; Checon, Juliana Tibério; Cesar, Camila Kappke; Mussi, Lilian; Polezel, Márcio Antonio; Martins-Oliveira, Divino; Di Stasi, Luiz Claudio

    2015-01-01

    The use of topical retinoids to treat skin disorders and ageing can induce local reactions, while oral retinoids are potent teratogens and produce several unwanted effects. This way, efforts to explore complementary care resources should be supported. Based on this, we evaluate the antiageing effects of a supercritical CO2 extract from Bidens pilosa L. (BPE-CO2A) containing a standardized multicomponent mixture of phytol, linolenic, palmitic, linoleic, and oleic acids. BPE-CO2A was assessed for its effects on human dermal fibroblasts (TGF-β1 and FGF levels using ELISA; collagen, elastin, and glycosaminoglycan by colorimetric assays, and mRNA expression of RXR, RAR, and EGFr by qRT-PCR) and human skin fragments (RAR, RXR, collagen, elastin, and glycosaminoglycan by immunohistochemical analysis). Levels of extracellular matrix elements, TGF-β1 and FGF, and EGFr gene expression were significantly increased by BPE-CO2A. The modulation of RXR and RAR was positively demonstrated after the treatment with BPE-CO2A or phytol, a component of BPE-CO2A. The effects produced by BPE-CO2A were similar to or better than those produced by retinol and retinoic acid. The ability to stimulate extracellular matrix elements, increase growth factors, and modulate retinoid and rexinoid receptors provides a basis for the development of preparation containing BPE-CO2A as an antiageing/skin-repair agent. PMID:25883669

  3. Antiageing Mechanisms of a Standardized Supercritical CO 2 Preparation of Black Jack (Bidens pilosa L.) in Human Fibroblasts and Skin Fragments.

    PubMed

    Dieamant, Gustavo; Pereda, Maria Del Carmen V; Nogueira, Cecília; Eberlin, Samara; Facchini, Gustavo; Checon, Juliana Tibério; Cesar, Camila Kappke; Mussi, Lilian; Polezel, Márcio Antonio; Martins-Oliveira, Divino; Di Stasi, Luiz Claudio

    2015-01-01

    The use of topical retinoids to treat skin disorders and ageing can induce local reactions, while oral retinoids are potent teratogens and produce several unwanted effects. This way, efforts to explore complementary care resources should be supported. Based on this, we evaluate the antiageing effects of a supercritical CO2 extract from Bidens pilosa L. (BPE-CO2A) containing a standardized multicomponent mixture of phytol, linolenic, palmitic, linoleic, and oleic acids. BPE-CO2A was assessed for its effects on human dermal fibroblasts (TGF-β1 and FGF levels using ELISA; collagen, elastin, and glycosaminoglycan by colorimetric assays, and mRNA expression of RXR, RAR, and EGFr by qRT-PCR) and human skin fragments (RAR, RXR, collagen, elastin, and glycosaminoglycan by immunohistochemical analysis). Levels of extracellular matrix elements, TGF-β1 and FGF, and EGFr gene expression were significantly increased by BPE-CO2A. The modulation of RXR and RAR was positively demonstrated after the treatment with BPE-CO2A or phytol, a component of BPE-CO2A. The effects produced by BPE-CO2A were similar to or better than those produced by retinol and retinoic acid. The ability to stimulate extracellular matrix elements, increase growth factors, and modulate retinoid and rexinoid receptors provides a basis for the development of preparation containing BPE-CO2A as an antiageing/skin-repair agent. PMID:25883669

  4. Numerical Simulation of CO2 Flooding of Coalbed Methane Considering the Fluid-Solid Coupling Effect

    PubMed Central

    Liu, Jianjun; Li, Guang; Zhang, Yue

    2016-01-01

    CO2 flooding of coalbed methane (CO2-ECBM) not only stores CO2 underground and reduces greenhouse gas emissions but also enhances the gas production ratio. This coupled process involves multi-phase fluid flow and coal-rock deformation, as well as processes such as competitive gas adsorption and diffusion from the coal matrix into fractures. A dual-porosity medium that consists of a matrix and fractures was built to simulate the flooding process, and a mathematical model was used to consider the competitive adsorption, diffusion and seepage processes and the interaction between flow and deformation. Due to the effects of the initial pressure and the differences in pressure variation during the production process, permeability changes caused by matrix shrinkage were spatially variable in the reservoir. The maximum value of permeability appeared near the production well, and the degree of rebound decreased with increasing distance from the production well. PMID:27031096

  5. Numerical Simulation of CO2 Flooding of Coalbed Methane Considering the Fluid-Solid Coupling Effect.

    PubMed

    Liu, Jianjun; Li, Guang; Zhang, Yue

    2016-01-01

    CO2 flooding of coalbed methane (CO2-ECBM) not only stores CO2 underground and reduces greenhouse gas emissions but also enhances the gas production ratio. This coupled process involves multi-phase fluid flow and coal-rock deformation, as well as processes such as competitive gas adsorption and diffusion from the coal matrix into fractures. A dual-porosity medium that consists of a matrix and fractures was built to simulate the flooding process, and a mathematical model was used to consider the competitive adsorption, diffusion and seepage processes and the interaction between flow and deformation. Due to the effects of the initial pressure and the differences in pressure variation during the production process, permeability changes caused by matrix shrinkage were spatially variable in the reservoir. The maximum value of permeability appeared near the production well, and the degree of rebound decreased with increasing distance from the production well. PMID:27031096

  6. Direct growth of highly dispersed MnCl2 · 4H2O nanostructures with different morphologies on graphene in supercritical CO2

    NASA Astrophysics Data System (ADS)

    Xu, Qin-Qin; Zhao, Xiao-Chen; Yin, Jian-Zhong; Xu, Gang

    2016-06-01

    Willow leaf-like Mn3O4 nanoplates@graphene nanocomposites were synthesized using graphene instead of graphene oxide as initial materials with the assistance of supercritical CO2. The near-zero surface tension and the gas-like viscosity of supercritical CO2 favored the intercalation and dispersion of precursors among the graphene nanosheets. In addition, MnCl2 · 4H2O ultra-small nanoparticles with diameter of 1–3 nm were supported on graphene using MnCl2 · 4H2O as precursor, supercritical CO2 as solvent and methanol as co-solvent under very moderate conditions. It was also found that the specific capacitance of the MnCl2 · 4H2O ultra-small nanoparticles@graphene with a metal loading of only 12.4% was twice that of pure graphene. In addition, the capacitance retention ratio of the MnCl2 · 4H2O ultra-small nanoparticles@graphene composite decreased by only 5.4% when the cycle number increased from 200 to 1000.

  7. Growth factors delivery from hybrid PCL-starch scaffolds processed using supercritical fluid technology.

    PubMed

    Diaz-Gomez, Luis; Concheiro, Angel; Alvarez-Lorenzo, Carmen; García-González, Carlos A

    2016-05-20

    Synthetic polymeric scaffolds to be used as surrogates of autologous bone grafts should not only have suitable physicochemical and mechanical properties, but also contain bioactive agents such as growth factors (GFs) to facilitate the tissue growth. For this purpose, cost-effective and autologous GFs sources are preferred to avoid some post-surgery complications after implantation, like immunogenicity or disease transmission, and the scaffolds should be processed using methods able to preserve GFs activity. In this work, poly(ɛ-caprolactone) (PCL) scaffolds incorporating GFs were processed using a green foaming process based on supercritical fluid technology. Preparation rich in growth factors (PRGF), a natural and highly available cocktail of GFs obtained from platelet rich plasma (PRP), was used as GF source. PCL:starch:PRGF (85:10:5 weight ratio) porous solid scaffolds were obtained by a supercritical CO2-assisted foaming process at 100 bar and 37 °C with no need of post-processing steps. Bioactivity of GFs after processing and scaffold cytocompatibility were confirmed using mesenchymal stem cells. The performance of starch as GF control release component was shown to be dependent on starch pre-gelification conditions. PMID:26917401

  8. Therapeutic Effect of Supercritical CO2 Extracts of Curcuma Species with Cancer Drugs in Rhabdomyosarcoma Cell Lines.

    PubMed

    Ramachandran, Cheppail; Quirin, Karl-W; Escalon, Enrique A; Lollett, Ivonne V; Melnick, Steven J

    2015-08-01

    Synergistic effect of supercritical CO2 extracts of Curcuma species with conventional chemotherapeutic drugs was investigated in human alveolar (SJRH30) and embryonal (RD) rhabdomyosarcoma cell lines. The Curcuma amada (mango ginger) (CA) extract showed the highest levels of cytotoxicity with inhibitory concentration IC50 values of 7.133 µg/ml and 7.501 µg/ml for SJRH30 and RD cell lines, respectively, as compared with Curcuma longa (turmeric) and Curcuma xanthorrhiza (Javanese turmeric) extracts. CA showed synergistic cytotoxic effects with vinblastine (VBL) and cyclophosphamide (CP) as indicated by the combination index values of <1 for VBL + CA, CP + CA, and VBL + CP + CA combinations in both embryonal and alveolar rhabdomyosarcomas. When lower doses of CA (0.1-0.2 µg/ml) were combined with cancer drugs like CP and VBL, caspase-3 activity increased significantly compared with individual agents and correlated with the percentage of apoptotic cells. CA in combination with VBL and CP induced a higher percentage of apoptosis than single agents in both cell lines. CA also modulated the expression of genes associated with intrinsic pathway of apoptosis (Bcl-2, Bax, Bak, and p53) and also inhibited the expression of genes associated with inflammation such as COX-2 and NF-κB. Xenograft studies with SJRH30 tumors in nude mice showed that CA treatment inhibited tumor growth rate with and without VBL and increased the survival rate significantly. These results suggest that CA can be evaluated further as an adjuvant with cancer drugs for the treatment of rhabdomyosarcoma patients. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25939344

  9. Supercritical CO2 Foaming of Thermoplastic Materials Derived from Maize: Proof-of-Concept Use in Mammalian Cell Culture Applications

    PubMed Central

    Trujillo-de Santiago, Grissel; Portales-Cabrera, Cynthia Guadalupe; Portillo-Lara, Roberto; Araiz-Hernández, Diana; Del Barone, Maria Cristina; García-López, Erika; Rojas-de Gante, Cecilia; de los Angeles De Santiago-Miramontes, María; Segoviano-Ramírez, Juan Carlos; García-Lara, Silverio; Rodríguez-González, Ciro Ángel; Alvarez, Mario Moisés; Di Maio, Ernesto; Iannace, Salvatore

    2015-01-01

    Background Foams are high porosity and low density materials. In nature, they are a common architecture. Some of their relevant technological applications include heat and sound insulation, lightweight materials, and tissue engineering scaffolds. Foams derived from natural polymers are particularly attractive for tissue culture due to their biodegradability and bio-compatibility. Here, the foaming potential of an extensive list of materials was assayed, including slabs elaborated from whole flour, the starch component only, or the protein fraction only of maize seeds. Methodology/Principal Findings We used supercritical CO2 to produce foams from thermoplasticized maize derived materials. Polyethylene-glycol, sorbitol/glycerol, or urea/formamide were used as plasticizers. We report expansion ratios, porosities, average pore sizes, pore morphologies, and pore size distributions for these materials. High porosity foams were obtained from zein thermoplasticized with polyethylene glycol, and from starch thermoplasticized with urea/formamide. Zein foams had a higher porosity than starch foams (88% and 85%, respectively) and a narrower and more evenly distributed pore size. Starch foams exhibited a wider span of pore sizes and a larger average pore size than zein (208.84 vs. 55.43 μm2, respectively). Proof-of-concept cell culture experiments confirmed that mouse fibroblasts (NIH 3T3) and two different prostate cancer cell lines (22RV1, DU145) attached to and proliferated on zein foams. Conclusions/Significance We conducted screening and proof-of-concept experiments on the fabrication of foams from cereal-based bioplastics. We propose that a key indicator of foamability is the strain at break of the materials to be foamed (as calculated from stress vs. strain rate curves). Zein foams exhibit attractive properties (average pore size, pore size distribution, and porosity) for cell culture applications; we were able to establish and sustain mammalian cell cultures on zein

  10. Operation and performance of the Supercritical Fluids Reactor (SFR)

    SciTech Connect

    Hanush, R.G.; Rice, S.F.; Hunter, T.B.; Aiken, J.D.

    1995-11-01

    The Supercritical Fluids Reactor (SFR) at Sandia National Laboratories, CA has been developed to examine and solve engineering, process, and fundamental chemistry issues regarding the development of supercritical water oxidation (SCWO). This report details the experimental apparatus, procedures, analytical methods used in these experiments, and performance characteristics of the reactor. The apparatus consists of pressurization, feed, preheat, reactor, cool down, and separation subsystems with ancillary control and data acquisition hardware and software. Its operating range is from 375 - 650{degrees} at 3250 - 6300 psi with resident times from 0.09 to 250 seconds. Procedures required for experimental operations are described. They include maintenance procedures conducted between experiments, optical alignment for acquisition of spectroscopic data, setup of the experiment, reactor start up, experimental operations, and shutdown of apparatus. Analytical methods used are Total Organic Carbon analysis, Gas Chromatography, ion probes, pH probes, turbidity measurements and in situ Raman spectroscopy. Experiments conducted that verify the accuracy of measurement and sampling methods are described.

  11. Selective chelation and extraction of lanthanides and actinides with supercritical fluids

    SciTech Connect

    Brauer, R.D.; Carleson, T.E.; Harrington, J.D.; Jean, F.; Jiang, H.; Lin, Y.; Wai, C.M.

    1994-01-01

    This report is made up of three independent papers: (1) Supercritical Fluid Extraction of Thorium and Uranium with Fluorinated Beta-Diketones and Tributyl Phosphate, (2) Supercritical Fluid Extraction of Lanthanides with Beta-Diketones and Mixed Ligands, and (3) A Group Contribution Method for Predicting the Solubility of Solid Organic Compounds in Supercritical Carbon Dioxide. Experimental data are presented demonstrating the successful extraction of thorium and uranium using fluorinated beta-diketones to form stable complexes that are extracted with supercritical carbon dioxide. The conditions for extracting the lanthanide ions from liquid and solid materials using supercritical carbon dioxide are presented. In addition, the Peng-Robison equation of state and thermodynamic equilibrium are used to predict the solubilities of organic solids in supercritical carbon dioxide from the sublimation pressure, critical properties, and a centric factor of the solid of interest.

  12. Efficient stripping of photoresist on metallized wafers by a pause flow of supercritical fluid.

    PubMed

    Chao, Mu-Rong; Chen, Jian-Lian

    2009-09-30

    Utilization of supercritical fluids (SCFs) is studied here on the premises of a saving of hazardous organic solvents and of the specification for stripping the photoresist (PR) on metallization layers, which is one of the integrated circuit processing modules. By using factorial experimental designs with five factors and four level ranges, this research focuses on determining an optimized recipe with high stripping efficiency and to determine the stripping mechanism. In the case of PR on an aluminum layer, the initial use of the pulse flow mode could increase the extraction ratio remarkably when compared to the conventional continuous flow mode. Based on the limitation of a total volume of 30 mL purging SCF-CO(2) for economical considerations, the optimum conditions can be summarized as follows: 120 degrees C, oven temperature; 350 atm, CO(2) pressure; 0.2 mL of ethylacetate spiking to SCF-CO(2); 2.0 min, static equilibrium time; and five cycles of dynamic flow pausing. A recovery of 94.6% (n=3, RSD=6.5%) was obtained, while the diffusion of stripped PR from substrate matrix prevailed over the dissolution of binding PR into the SCF medium. In the case of copper, the optimum parameters in a pause flow mode were 140 degrees C, oven temperature; 500 atm, CO(2) pressure; 0.75 mL, ethylacetate spiking volume; 5.0 min, static time; and six cycles of flow pausing. These extreme parameters still did not produce an SCF environment suitable for diffusion or dissolution mass transfer, and thus a recovery of 76.2% (n=3, RSD=7.5%) was only obtained. Removing PR coated on a Cu layer was harder than that on an Al layer. PMID:19376650

  13. 'Structure, Dynamics and Vibrational Spectrum of Supercritical CO2/H2O Mixtures from Ab Initio Molecular Dynamics as a Function of Water Cluster Formation

    SciTech Connect

    Glezakou, Vassiliki Alexandra; Rousseau, Roger J.; Dang, Liem X.; McGrail, B. Peter

    2010-08-21

    We have studied the effect of water in the supercritical phase of CO2 as a function of water self-association using DFT-based molecular dynamics simulations. The dependence of the intermolecular and intramolecular structure and dynamic properties upon water concentration in the supercritical CO2/H2O phase at a density of 0.81g/cm3 and temperature of 318.15K is investigated in detail and compared to previous studies of the pure sc-CO2 system and Monte-Carlo simulations of water in sc-CO2 phase. Analysis of radial and orientational distribution functions of the intermolecular interactions shows that the presence of water molecules does not disturb the previously established distorted T-shaped orientation of CO2 molecules, though there is strong evidence of perturbation of the second shell structure which enhances the preference for the slipped parallel orientation in this region. There is also evidence of short-lived hydrogen bonds between CO2 and water molecules. For higher water concentrations, water clustering is observed, consistent with the expected phase separation under these conditions of temperature and pressure. Finally, the water-water and water-CO2 interactions are discussed and analyzed in terms of the water self-association and thermodynamic quantities derived from the corresponding radial distribution functions. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  14. Micronutrient and protein-fortified whole grain puffed rice made by supercritical fluid extrusion.

    PubMed

    Paraman, Ilankovan; Wagner, Michael E; Rizvi, Syed S H

    2012-11-01

    Supercritical fluid extrusion (SCFX) was used to produce shelf-stable puffed rice fortified with protein, dietary fiber, and micronutrients. Product ingredients and process parameters were evaluated for end-product nutritional and textural qualities. Supercritical carbon dioxide (SC-CO(2)) served as a viscosity-lowering plasticizer and blowing agent during the process, which has been shown to produce expanded products with good textural qualities at lower temperatures (~100 °C) than conventional steam-based extrusion (130-180 °C). The fortified puffed rice contained 8% dietary fiber, 21.5% protein, and iron, zinc, and vitamins A and C at their recommended daily values in 100 g of product. The SCFX process allowed for the complete retention of all added minerals, 55-58% retention of vitamin A, and 64-76% retention of vitamin C. All essential amino acids including lysine were retained at exceptionally high levels (98.6%), and no losses were observed due to Maillard reaction or oxidation. All of the essential amino acid contents were equal to the reference protein recommended by FAO/WHO. Soy protein fortification improved the total amount of protein in the final rice products and provided a complementary amino acid profile to that of rice; the lysine content improved from 35 to 60 mg/protein, making the end product an excellent source of complete protein. Thus, SC-CO(2)-assisted extrusion is an effective process-based approach to produce cereal grain-based, low-moisture (5-8%) expanded products fortified with protein and any cocktail of micronutrients, without compromising the end-product sensory or nutritional qualities. These products are ideally suited for consumption as breakfast cereals, snack foods, and as part of nutrition bars for school lunch programs. The balanced nutritional profile and use of staple crop byproducts such as broken rice makes these expanded crisps unique to the marketplace. PMID:23066826

  15. Volume-energy parameters for heat transfer to supercritical fluids

    NASA Technical Reports Server (NTRS)

    Kumakawa, A.; Niino, M.; Hendricks, R. C.; Giarratano, P. J.; Arp, V. D.

    1986-01-01

    Reduced Nusselt numbers of supercritical fluids from different sources were grouped by several volume-energy parameters. A modified bulk expansion parameter was introduced based on a comparative analysis of data scatter. Heat transfer experiments on liquefied methane were conducted under near-critical conditions in order to confirm the usefulness of the parameters. It was experimentally revealed that heat transfer characteristics of near-critical methane are similar to those of hydrogen. It was shown that the modified bulk expansion parameter and the Gibbs-energy parameter grouped the heat transfer data of hydrogen, oxygen and methane including the present data on near-critical methane. It was also indicated that the effects of surface roughness on heat transfer were very important in grouping the data of high Reynolds numbers.

  16. Enantiomeric composition studies in Lavandula species using supercritical fluids.

    PubMed

    Flores, Gema; Blanch, Gracia Patricia; Ruiz del Castillo, Maria Luisa; Herraiz, Marta

    2005-11-01

    Characteristic aroma compounds in plants and essential oils of Lavandula from different varieties were examined. The study of the qualitative and quantitative composition of the major volatile components was faced by developing a method based on the use of supercritical fluid extraction-GC-MS (SFE-GC-MS). The optimization of a variety of parameters affecting SFE extraction enabled RSDs from three replicates lower than 2% to be achieved. Equally, recoveries of up to 59% were obtained by applying the proposed method. The use of multidimensional GC was necessary to enantiomerically resolve the target compounds. The obtained results showed enantiomeric purities >90% for all studied compounds in all varieties considered, proving the natural invariability of the enantiomeric composition of the compounds of interest. This information can be useful in authenticity studies as well as in selecting natural sources of enantiomerically pure compounds. PMID:16342799

  17. Subsurface fluid data from Longyearbyen CO2 storage site: Basin history and compartmentalization

    NASA Astrophysics Data System (ADS)

    Huq, Farhana; Mueller, Kristin; Tore Mørkved, Pål; Johansen, Ingar; Johansen, Harald

    2015-04-01

    The Longyearbyen CO2 storage site, located on the main island of Svalbard at the northwestern margin of the Barents Sea Shelf, is a demonstration project for a "green showcase", which aims to make a full value chain of power generation, CO2 capture and storage by achieving a net zero carbon footprint. The key objective of this study was to assess the local geological conditions for CO2 storage by defining a seal sequence stratigraphy above and within the reservoir from gas and fluid geochemical data. Seven wells were drilled at two sites to collect core material and gas samples at various defined depths. Gas composition (C1-5, CO2) and stable isotope (δ13C) analyses were performed on gas samples obtained from both core material and well heads. In addition, Sr isotope data from residual salts extracted from core material were used to look at compartmentalization. The combined analysis of trends in isotope and gas composition data as a function of depth revealed three major breaks and permitted the identification of three major fluid compartments. These compartments are suggested to be associated with impervious caprock and reservoir barriers. The first break in the data trends occurs at approximately 250-300 m depth, which is interpreted as the depth limit of the meteoric water system. A second hydrologic barrier, most likely produced by reservoir uplift was identified. Finally, a very distinct change in trend around 800 m depth may be associated with an observed significant change in reservoir pressure. Three clear breaks in the geochemical data as a function of depth all point towards an efficient seal sequence and demonstrate the potential for CO2 storage at the Longyearbyen site.

  18. Application of supercritical CO2 for extraction of polyisoprenoid alcohols and their esters from plant tissues[S

    PubMed Central

    Jozwiak, Adam; Brzozowski, Robert; Bujnowski, Zygmunt; Chojnacki, Tadeusz; Swiezewska, Ewa

    2013-01-01

    In this study, a method of supercritical fluid extraction (SFE) with carbon dioxide of polyisoprenoids from plant photosynthetic tissues is described. SFE was an effective extraction method for short- and medium-chain compounds with even higher yield than that observed for the “classical extraction” method with organic solvents. Moreover, SFE-derived extracts contained lower amounts of impurities (e.g., chlorophylls) than those obtained by extraction of the same tissue with organic solvents. Elevated temperature and extended extraction time of SFE resulted in a higher rate of extraction of long-chain polyisoprenoids. Ethanol cofeeding did not increase the extraction efficiency of polyisoprenoids; instead, it increased the content of impurities in the lipid extract. Optimization of SFE time and temperature gives the opportunity of prefractionation of complex polyisoprenoid mixtures accumulated in plant tissues. Extracts obtained with application of SFE are very stable and free from organic solvents and can further be used directly in experimental diet supplementation or as starting material for preparation of semisynthetic polyisoprenoid derivatives, e.g., polyisoprenoid phosphates. PMID:23673976

  19. Removal of pollutants from solid matrices using supercritical fluids

    SciTech Connect

    Tomasko, D.L.; Macnaughton, S.J.; Foster, N.R.

    1995-04-01

    Several supercritical fluid extraction (SCFE) processes have been proposed for removing toxic and intractable organic compounds from a range of contaminated solids. These include soil remediation and the regeneration of absorbents used to treat wastewater streams such as granular activated carbon (GAC). As a separation technique for environmental control, SCFR has several distinct advantages over conventional liquid extraction methods and incineration. Most notably, the contaminant is removed from the solvent in a concentrated form via a change in pressure or temperature and can be completely separated upon expansion to atmospheric pressure. The viability of SCFE hinges on process conditions such as solvent-feed ratio and solvent recycle ratio. The necessity of recycling solvent complicates the contaminant separation step since a complete reduction to atmospheric pressure would create large recompression costs. Because of this, the pressure and temperature dependence of contaminant solubility must be understood so that operating conditions for the separation step can be defined. Fortunately, this is the most developed aspect of SCF technology. However, the mass transfer limitations to removing contaminants from solids change with solvent flow rate. This paper discusses the use of SCFE for environmental control and presents results for the removal of DDT and 2-chlorophenol from GAC. 2-chlorophenol is almost completely removed with pure CO{sub 2} at 40{degrees}C and 101 bar while only 55% of the DDT is removed at 40{degrees}C and 200 bar. These differences in regeneration efficiency cannot be understood solely in terms of solubility but point to a need for detailed studies of adsorption equilibrium and mass transfer resistances in supercritical fluid systems.