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Sample records for supercritical co2 fluid

  1. 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

  2. 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

  3. 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.

  4. 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

  5. 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...

  6. 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.

  7. Dehydroxyl effect of Sn-doped silicon oxide resistance random access memory with supercritical CO2 fluid treatment

    NASA Astrophysics Data System (ADS)

    Tsai, Tsung-Ming; Chang, Kuan-Chang; Chang, Ting-Chang; Syu, Yong-En; Liao, Kuo-Hsiao; Tseng, Bae-Heng; Sze, Simon M.

    2012-09-01

    The tin-doped can supply conduction path to induce resistance switching behavior. However, the defect of tin-doped silicon oxide (Sn:SiOx) increased the extra leakage path lead to power consumption and joule heating degradation. In the study, supercritical CO2 fluids treatment was used to improve resistive switching property. The current conduction of high resistant state in post-treated Sn:SiOx film was transferred to Schottky emission from Frenkel-Poole due to the passivation effect. The molecular reaction model is proposed that the defect was passivated through dehydroxyl effect of supercritical fluid technology, verified by material analyses of x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy.

  8. 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

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

    DOE PAGES

    Zhang, Le; Luo, Feng; Xu, Ruina; ...

    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

  10. 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

  11. Dielectric Interactions and the Prediction of Retention Times of Pesticides in Supercritical Fluid Chromatography with CO2

    NASA Astrophysics Data System (ADS)

    Alvarez, Guillermo A.; Baumanna, Wolfram

    2005-02-01

    A thermodynamic model for the partition of a solute (pesticide) between two immiscible phases, such as the stationary and mobile phases of supercritical fluid chromatography with CO2, is developed from first principles. A key ingredient of the model is the result of the calculation made by Liptay of the energy of interaction of a polar molecule with a dielectric continuum, which represents the solvent. The strength of the interaction between the solute and the solvent, which may be considered a measure of the solvent power, is characterized by a function g = (ɛ - 1)/(2ɛ +1), where ɛ is the dielectric constant of the medium, which is a function of the temperature T and the pressure P. Since the interactions between the nonpolar supercritical CO2 solvent and the slightly polar pesticide molecules are considered to be extremely weak, a regular solution model is appropriate from the thermodynamic point of view. At constant temperature, the model predicts a linear dependence of the logarithm of the capacity factor (lnk) of the chromatographic experiment on the function g = g(P), as the pressure is varied, with a slope which depends on the dipole moment of the solute, dispersion interactions and the size of the solute cavity in the solvent. At constant pressure, once the term containing the g (solvent interaction) factor is subtracted from lnk, a plot of the resulting term against the inverse of temperature yields the enthalpy change of transfer of the solute from the mobile (supercritical CO2) phase to the stationary (adsorbent) phase. The increase in temperature with the consequent large volume expansion of the supercritical fluid lowers its solvent strength and hence the capacity factor of the column (or solute retention time) increases. These pressure and temperature effects, predicted by the model, agree excellently with the experimental retention times of seven pesticides. Beyond a temperature of about 393 K, where the liquid solvent densities approach those of

  12. How does the critical point change during a chemical reaction in supercritical fluids? A study of the hydroformylation of propene in supercritical CO(2).

    PubMed

    Ke, J; Han, B; George, M W; Yan, H; Poliakoff, M

    2001-04-25

    An understanding of homogeneous catalysis in supercritical fluids requires a knowledge of the phase behavior and the variation in critical point as the reaction proceeds. In this paper, the critical temperatures, T(c) and pressures, P(c), have been measured for a considerable number of mixtures representing the various stages of the hydroformylation reaction of propene in supercritical CO(2) and different reactant concentrations. Critical point data have also been measured for all of the binary mixtures of the components (CO(2), H(2), CO, propene, n- and isobutyraldehyde) which are not available from the literature or can be deduced from published data. We use the stoichiometry of the reacting system to simplify greatly the phase behavior problem by defining a path through the otherwise multidimensional "phase space". Satisfactory modeling of the data (0.3% in T(c) and 3.0% in P(c)) has been achieved using the Peng-Robinson equation of state and ignoring all binary interactions which do not involve CO(2). The model is used to explore the strategies needed to avoid phase separation in continuous and batch reactions. At a given temperature, a batch reactor may need to be run under much higher pressures than a flow reactor if single-phase conditions are to be preserved throughout the course of the reaction. Most of the critical point data were measured acoustically, but a selection of points were validated using more traditional view-cell procedures.

  13. 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

  14. 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

  15. Molecular dynamics simulation of the key characteristics of the supercritical CO2-pentaerythritol tetraacetate system

    NASA Astrophysics Data System (ADS)

    Lei, Peiyu; Jin, Zunlong; Liu, Hong; Wang, Dingbiao; Liu, Donglai

    2016-12-01

    Supercritical CO2 is widely used in many fields of industry. Investigation of statistical mechanics of CO2 fluid under quasi critical and supercritical state has great significance. Equilibrium molecular dynamics (EMD) simulations are carried out to investigate the statistical mechanics and macroscopic performance of CO2 fluid under the quasi critical and supercritical state. The results show that the bond length and bond angle distributions for supercritical CO2 are Gaussian distribution basically. The dimers' proportion of supercritical CO2 system changes with pressure increasing. T-type dimer has high share within the system when pressure is higher than 9MPa. It can be inferred that T-type dimer leads to CO2 physical properties changing tempestuously under supercritical state. The effect that lubricating oil has on microstructure and heat transfer of supercritical CO2 is also investigated in the present work. The results show the lubricating oil produces significant effect on the dimers' structure under low pressure.

  16. 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

  17. 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

  18. Microbial growth under supercritical CO2.

    PubMed

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

    2015-04-01

    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.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. Effects of Natural Osmolytes on the Protein Structure in Supercritical CO2: Molecular Level Evidence.

    PubMed

    Monhemi, Hassan; Housaindokht, Mohammad Reza; Nakhaei Pour, Ali

    2015-08-20

    Protein instability in supercritical CO2 limits the application of this green solvent in enzyme-catalyzed reactions. CO2 molecules act as a protein denaturant at high pressure under supercritical conditions. Here, for the first time, we show that natural osmolytes could stabilize protein conformation in supercritical CO2. Molecular dynamics simulation is used to monitor the effects of adding different natural osmolytes on the conformation and dynamics of chymotrypsin inhibitor 2 (CI2) in supercritical CO2. Simulations showed that CI2 is denatured at 200 bar in supercritical CO2, which is in agreement with experimental observations. Interestingly, the protein conformation remains native after addition of ∼1 M amino acid- and sugar-based osmolyte models. These molecules stabilize protein through the formation of supramolecular self-assemblies resulting from macromolecule-osmolyte hydrogen bonds. Nevertheless, trimethylamine N-oxide, which is known as a potent osmolyte for protein stabilization in aqueous solutions, amplifies protein denaturation in supercritical CO2. On the basis of our structural analysis, we introduce a new mechanism for the osmolyte effect in supercritical CO2, an "inclusion mechanism". To the best of our knowledge, this is the first study that introduces the application of natural osmolytes in a supercritical fluid and describes mechanistic insights into osmolyte action in nonaqueous media.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Design of experimental setup for supercritical CO2 jet under high ambient pressure conditions.

    PubMed

    Shi, Huaizhong; Li, Gensheng; He, Zhenguo; Wang, Haizhu; Zhang, Shikun

    2016-12-01

    With the commercial extraction of hydrocarbons in shale and tight reservoirs, efficient methods are needed to accelerate developing process. Supercritical CO2 (SC-CO2) jet has been considered as a potential way due to its unique fluid properties. In this article, a new setup is designed for laboratory experiment to research the SC-CO2 jet's characteristics in different jet temperatures, pressures, standoff distances, ambient pressures, etc. The setup is composed of five modules, including SC-CO2 generation system, pure SC-CO2 jet system, abrasive SC-CO2 jet system, CO2 recovery system, and data acquisition system. Now, a series of rock perforating (or case cutting) experiments have been successfully conducted using the setup about pure and abrasive SC-CO2 jet, and the results have proven the great perforating efficiency of SC-CO2 jet and the applications of this setup.

  12. Synthesis of siliceous hollow spheres with large mesopore wall structure by supercritical CO2-in-water interface templating.

    PubMed

    Wang, Jiawei; Xia, Yongde; Wang, Wenxin; Mokaya, Robert; Poliakoff, Martyn

    2005-01-14

    Hollow silica spheres with large mesopore wall structures have been synthesized via CO(2)-in-water emulsion templating in the presence of PEO-PPO-PEO block copolymers under supercritical fluid conditions.

  13. 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.

  14. The combined extraction of sage (Salvia officinalis L.): ultrasound followed by supercritical CO2 extraction.

    PubMed

    Glisic, Sandra B; Ristic, Mihajlo; Skala, Dejan U

    2011-01-01

    A wide spectrum of phytochemicals could be isolated from sage (Salvia officinalis L.) using different extraction or distillation technique: the supercritical fluid extraction (SFE), the volatiles compounds (monoterpenes and sesquiterpenes) isolation using hydrodistillation or higher molecular compounds with Soxhlet extraction or ultrasound-assisted extraction. The combination of ultrasound-assisted extraction followed by re-extraction of obtained extract with supercritical CO(2) was performed in this study. The goal of performed investigation was to concentrate diterpenes present in sage extract which are generally considered to be responsible for antioxidant activity of extracted compounds. The fractionation using the supercritical CO(2), and different combination of the ultrasound-assisted solvent extractions (water-ethanol mixture or only water) followed by supercritical CO(2) re-extraction of obtained extract or treated plant material were analyzed and compared. Based on the results of these investigations it could be proposed the best extraction procedure: the ultrasound pretreatment of plant material with distilled water and re-extraction of plant material (residue) using supercritical CO(2). That procedure gives two valuable products: the ultrasound extract which is rich in sugars and possess the immunomodulatory activity and supercritical extract which is rich in diterpenes and sesquiterpenes.

  15. 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.

  16. 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.

  17. 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.

  18. 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...

  19. 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.

  20. 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.

  1. Enhancing residual trapping of supercritical CO2 via cyclic injections

    NASA Astrophysics Data System (ADS)

    Herring, Anna L.; Andersson, Linnéa.; Wildenschild, Dorthe

    2016-09-01

    We utilize synchrotron X-ray tomographic imaging to investigate the pore-scale characteristics and residual trapping of supercritical CO2 (scCO2) over the course of multiple drainage-imbibition (D-I) cycles in Bentheimer sandstone cores. Capillary pressure measurements are paired with X-ray image-derived saturation and connectivity metrics which describe the extent of drainage and subsequent residual (end of imbibition) scCO2 trapping. For the first D-I cycle, residual scCO2 trapping is suppressed due to high imbibition capillary number (Ca ≈ 10-6); however, residual scCO2 trapping dramatically increases for subsequent D-I cycles carried out at the same Ca value. This behavior is not predicted by conventional multiphase trapping theory. The magnitude of scCO2 trapping increase is hysteretic and depends on the relative extent of the sequential drainage processes. The hysteretic pore-scale behavior of the scCO2-brine-sandstone system observed in this study suggests that cyclic multiphase flow could potentially be used to increase scCO2 trapping for sequestration applications.

  2. 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

  3. Polymeric nanoporous materials fabricated with supercritical CO2 and CO2-expanded liquids.

    PubMed

    Zhang, Aijuan; Zhang, Qingkun; Bai, Hua; Li, Lei; Li, Jun

    2014-01-01

    Both academia and industries have put great efforts into developing non-destructive technologies for the fabrication of polymeric nanoporous materials. Such non-destructive technologies developed with supercritical CO2 (scCO2) and CO2-expanded liquids (CXLs) have been attracting more and more attention because they have been demonstrated to be green and effective media for porous polymer preparation and processing. In this tutorial review, we present several such new technologies with scCO2 and CXLs, which have the capacity to prepare polymeric nanoporous materials with unique morphologies. The fabricated nanoporous polymers have significantly improved the performance of polymeric monoliths and films, and have found wide applications as templates, antireflection coatings, low-k materials, tissue engineering scaffolds and filtration membranes. This tutorial review also introduces the associated characterization methods, including the imaging, scattering and physisorption techniques.

  4. 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.

  5. Extraction of oil from wheat germ by supercritical CO2.

    PubMed

    Piras, Alessandra; Rosa, Antonella; Falconieri, Danilo; Porcedda, Silvia; Dessì, Maria A; Marongiu, Bruno

    2009-07-15

    This study examined the supercritical fluid extraction of wheat germ oil. The effects of pressure (200-300 bar at 40 degrees C) and extraction time on the oil quality/quantity were studied. A comparison was also made between the relative qualities of material obtained by SFE and by organic solvent extraction. The extracts were analyzed for alpha-tocopherol and polyunsaturated fatty acid content. The maximum wheat germ oil yield at about 9% was obtained with supercritical carbon dioxide extraction at 300 bar, while fatty acid and alpha-tocopherol composition of the extracts was not remarkable affected by either pressure or the extraction method.

  6. 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.

  7. 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

  8. 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

  9. Measuring water adsorption on mineral surfaces in air, CO2, and supercritical CO2 with a quartz-crystal microbalance

    NASA Astrophysics Data System (ADS)

    Bryan, C. R.; Wells, R. K.; Burton, P. D.; Heath, J. E.; Dewers, T. A.; Wang, Y.

    2011-12-01

    Carbon sequestration via underground storage in geologic formations is a proposed approach for reducing industrial CO2 emissions. However, current models for carbon injection and long-term storage of supercritical CO2 (scCO2) do not consider the development and stability of adsorbed water films at the scCO2-hydrophilic mineral interface. The thickness and properties of the water films control the surface tension and wettability of the mineral surface, and on the core scale, affect rock permeability, saturation, and capillary properties. The film thickness is strongly dependent upon the activity of water in the supercritical fluid, which will change as initially anhydrous scCO2 absorbs water from formation brine. As described in a companion paper by the coauthors, the thickness of the adsorbed water layer is controlled by the disjoining pressure; structural and van der Waals components dominate at low water activity, while electrostatic forces become more important with increasing film thickness (higher water activities). As scCO2 water activity and water layer thickness increase, concomitant changes in mineral surface properties and reservoir/caprock hydrologic properties will affect the mobility of the aqueous phase and of scCO2. Moreover, the development of a water layer may be critical to mineral dissolution reactions in scCO2. Here, we describe the use of a quartz-crystal microbalance (QCM) to monitor adsorption of water by mineral surfaces. QCMs utilize a piezoelectrically-stimulated quartz wafer to measure adsorbed or deposited mass via changes in vibrational frequency. When used to measure the mass of adsorbed liquid films, the frequency response of the crystal must be corrected for the viscoelastic, rather than elastic, response of the adsorbed layer. Results are presented for adsorption to silica in N2 and CO2 at one bar, and in scCO2. Additional data are presented for water uptake by clays deposited on a QCM wafer. In this case, water uptake occurs by the

  10. Supercritical fluid impregnation of polyethylene films, a new approach to studying equilibria in matrices; the hydrogen bonding of fluoroalcohols to (η 5-C 5Me 5)Ir(CO) 2 and the effect on CH activation

    NASA Astrophysics Data System (ADS)

    Cooper, Andrew I.; Kazarian, Sergei G.; Poliakoff, Martyn

    1993-04-01

    Polyethylene (PE) film is used as a matrix for studying temperature-dependent equilibria by IR spectroscopy; the film is impregnated with Cp*Ir(CO) 2 (Cp*=η 5-C 5Me 5) using supercritical CO 2 and subsequently saturated with HOR F (R F=(CF 3) 2CH or (CF 3) 3C). At 200 K, the equilibrium between Cp*Ip(CO) 2 and the hydrogen-bonded complex, Cp*Ir(CO) 2…HOR F, is frozen out and can be disturbed photochemically, because Cp*Ir(CO) 2 is more efficient than Cp*Ir(CO) 2…HOR F for CH activation of polyethylene.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. Supercritical CO(2) extraction of beta-carotene and lycopene from tomato paste waste.

    PubMed

    Baysal, T; Ersus, S; Starmans, D A

    2000-11-01

    Lycopene and beta-carotene were extracted from tomato paste waste using supercritical carbon dioxide (SC-CO(2)). To optimize supercritical fluid extraction (SFE) results for the isolation of lycopene and beta-carotene, a factorial designed experiment was conducted. The factors assessed were the temperature of the extractor (35, 45, 55, and 65 degrees C), the pressure of the extraction fluid (200, 250, and 300 bar), addition of cosolvent (5, 10, and 15% ethanol), extraction time (1, 2, and 3 h), and CO(2) flow rate (2, 4, and 8 kg/h). The total amounts of lycopene and beta-carotene in the tomato paste waste, extracts, and residues were determined by HPLC. A maximum of 53.93% of lycopene was extracted by SC-CO(2) in 2 h (CO(2) flow rate = 4 kg/h) at 55 degrees C and 300 bar, with the addition of 5% ethanol as a cosolvent. Half of the initially present beta-carotene was extracted in 2 h (flow rate = 4 kg/h), at 65 degrees C and 300 bar, also with the addition of 5% ethanol.

  16. Supercritical CO2 extraction of essential oils from Chamaecyparis obtusa.

    PubMed

    Jin, Yinzhe; Han, Dandan; Tian, Minglei; Row, Kyung-Ho

    2010-03-01

    Supercritical carbon dioxide (SC-CO2) extraction and hydrodistillation (HD) were used to determine the essential oil composition of the trunks and leaves of Chamaecyparis obtusa. The optimal extraction conditions for the oil yield within the experimental range of variables examined were temperature 50 degrees C, pressure 12 MPa, carbon dioxide flow rate 40 mL/min and extraction time 90 min. The maximum measured extraction yield was 2.9%. Entrainer solvents, such as methanol in water, had no additional effect on the extraction of essential oils. The chemical composition of the essential oils was analyzed by GC-MS. The major components were alpha-terpinyl acetate (>10.9%), 1-muurolol (>13.2%) and elemol (>8.1%). Sesquiterpenoids formed the major class of compounds present.

  17. 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).

  18. Use of liquid/supercritical CO2 extraction process for butanol recovery from fermentation broth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order for butanol fermentation to be a viable option, it is essential to recover it from fermentation broth using economical alternate in-situ product recovery techniques such as liquid/supercritical CO2 extraction as compared to distillation. This technique (liquid CO2 extraction & supercritical...

  19. 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.

  20. 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).

  1. 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.

  2. 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.

  3. 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.

  4. Particle seeding enhances interconnectivity in polymeric scaffolds foamed using supercritical CO(2).

    PubMed

    Collins, Niki J; Bridson, Rachel H; Leeke, Gary A; Grover, Liam M

    2010-03-01

    Foaming using supercritical CO(2) is a well-known process for the production of polymeric scaffolds for tissue engineering. However, this method typically leads to scaffolds with low pore interconnectivity, resulting in insufficient mass transport and a heterogeneous distribution of cells. In this study, microparticulate silica was added to the polymer during processing and the effects of this particulate seeding on the interconnectivity of the pore structure and pore size distribution were investigated. Scaffolds comprising polylactide and a range of silica contents (0-50 wt.%) were produced by foaming with supercritical CO(2). Scaffold structure, pore size distributions and interconnectivity were assessed using X-ray computed microtomography. Interconnectivity was also determined through physical measurements. It was found that incorporation of increasing quantities of silica particles increased the interconnectivity of the scaffold pore structure. The pore size distribution was also reduced through the addition of silica, while total porosity was found to be largely independent of silica content. Physical measurements and those derived from X-ray computed microtomography were comparable. The conclusion drawn was that the architecture of foamed polymeric scaffolds can be advantageously manipulated through the incorporation of silica microparticles. The findings of this study further establish supercritical fluid foaming as an important tool in scaffold production and show how a previous limitation can be overcome.

  5. 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.

  6. 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.

  7. Mass spectrometry with direct supercritical fluid injection

    SciTech Connect

    Smith, R.D.; Udseth, H.R.

    1983-12-01

    Direct fluid injection mass spectrometry utilizes supercritical fluids for solvation and transfer of materials to a mass spectrometer chemical ionization (CI) source. Available data suggest that any material soluble in a supercritical fluid is transferred efficiently to the ionization region. Mass spectra are presented for mycotoxins of the trichothecene group obtained by use of supercritical carbon dioxide with isobutane as the CI reagent gas. Direct fluid injection MS/MS is also illustrated for major ions in the isobutane chemical ionization of T-2 toxin. The effect of pressure and temperature upon solubility in supercritical fluids is described and illustrated for diacetoxycirpenol. A potential method is also demonstrated for on-line fraction during MS analysis using pressure to control supercritical fluid solubility. Mass spectra are also presented for polar compounds, using supercritical ammonia, and the extension to complex mixtures is described. The fundamental basis and experimental requirements of the direct fluid injection process are discussed. 34 references, 11 figures, 1 table.

  8. Mass spectrometry with direct supercritical fluid injection

    SciTech Connect

    Smith, R.D.; Udseth, H.R.

    1983-12-01

    Direct fluid injection mass spectrometry utilizes supercritical fluids for solvation and transfer of materials to a mass spectrometer chemical ionization (CI) source. Available data suggest that any material soluble in a supercritical fluid is transferred efficiently to the ionization region. Mass spectra are presented for mycotoxins of the trichothecene group obtained by use of supercritical carbon dioxide with isobutane as the CI reagent gas. Direct fluid injection MS/MS is also illustrated for major ions in the isobutane chemical ionization of T-2 toxin. The effect of pressure and temperature upon solubility in supercritical fluids is described and illustrated for diacetoxyscirpenol. A potential method is also demonstrated for ''on-line fractionation'' during MS analysis using pressure to control supercritical fluid solubility. Mass spectra are also presented for polar compounds, using supercritical ammonia, and the extension to complex mixtures is described. The fundamental basis and experimental requirements of the direct fluid injection process are discussed. 1 figure, 11 tables.

  9. 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

  10. Experimental insights into the geochemistry and mineralogy of a granite-hosted geothermal system injected with supercritical CO2

    NASA Astrophysics Data System (ADS)

    Lo Re, C.; Kaszuba, J. P.; Moore, J.; McPherson, B. J.

    2011-12-01

    Supercritical CO2 may be a viable working fluid in enhanced geothermal systems (EGS) due to its large expansivity, low viscosity, and reduced reactivity with rock as compared to water. Hydrothermal experiments are underway to evaluate the geochemical impact of using supercritical CO2 as a working fluid in granite-hosted geothermal systems. Synthetic aqueous fluid and a model granite are reacted at 250 °C and 250 bars in a rocking autoclave and Au-Ti reaction cell for a minimum of 28 days (water:rock ratio of approximately 20:1). Subsequent injection of supercritical CO2 increases pressure, which decays over time as the CO2 dissolves into the aqueous fluid. Initial experiments decreased to a steady state pressure of 450 bars approximately 14 hours after injection of supercritical CO2. Post-injection reaction is allowed to continue for at least an additional 28 days. Excess CO2 is injected to produce a separate supercritical fluid phase (between 1.7 and 3.1 molal), ensuring aqueous CO2 saturation for the duration of each experiment. The granite was created using mineral separates and consists of ground (75 wt%, <45 microns) and chipped (25 wt%, 0.5-1.0 cm), sub-equal portions of quartz, perthitic potassium feldspar (~ 25 wt% albite and 75 wt% potassium feldspar), oligoclase, and a minor (4 wt%) component of Fe-rich biotite. The synthetic saline water (I = 0.12 m) contains molal quantities of Na, Cl, and HCO3 and millimolal quantities of K, SiO2, SO4, Ca, Al, and Mg, in order of decreasing molality. Aqueous fluids are sampled approximately 10 times over the course of each experiment and analyzed for total dissolved carbon and sulfide by coulometric titration, anions by ion chromatography, and major, minor, and trace cations by ICP-OES and -MS. Bench pH measurements are paired with aqueous analyses to calculate in-situ pH. Solid reactants are evaluated by SEM-EDS, XRD, and/or bulk chemical analysis before and after each experiment. Analytical data are reviewed

  11. Simulation studies on Enhanced Geothermal Systems with CO2 as a working fluid

    NASA Astrophysics Data System (ADS)

    Karra, S.; Ayling, B.; Han, W.; Lichtner, P. C.; Lu, C.; McPherson, B. J.; Mclin, K. S.; Moore, J.; Pan, F.; Rose, P. E.; Xu, T.

    2011-12-01

    Supercritical CO2 has recently been considered as a working fluid in enhanced geothermal systems (EGS), given its non-ionic nature, larger expansivity and lower viscosity compared to water. In addition, an EGS with supercritical CO2 as a working fluid may also act as a mechanism for CO2 sequestration. To explore this, one must understand the various interactions that may take place between the reservoir rock and the supercritical CO2. In this work, we perform simulations in two and three dimensions using the massively parallel flow and transport code PFLOTRAN, to study these interactions under various conditions (aqueous, non-aqueous and two-phase). The two dimensional results using PFLOTRAN are compared with simulations made using the TOUGH2 code. Numerical studies examining mineral dissolution and precipitation reactions that may occur in EGS that use supercritical CO2 are also shown, in addition to preliminary indications of which well placements may enable optimal flow rates and simultaneous CO2 sequestration.

  12. Water-in-Supercritical CO2 Microemulsion Stabilized by a Metal Complex.

    PubMed

    Luo, Tian; Zhang, Jianling; Tan, Xiuniang; Liu, Chengcheng; Wu, Tianbin; Li, Wei; Sang, Xinxin; Han, Buxing; Li, Zhihong; Mo, Guang; Xing, Xueqing; Wu, Zhonghua

    2016-10-17

    Herein we propose for the first time the utilization of a metal complex for forming water-in-supercritical CO2 (scCO2 ) microemulsions. The water solubility in the metal-complex-stabilized microemulsion is significantly improved compared with the conventional water-in-scCO2 microemulsions stabilized by hydrocarbons. Such a microemulsion provides a promising route for the in situ CO2 reduction catalyzed by a metal complex at the water/scCO2 interface.

  13. 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.; Thompson, C.; Ilton, E. S.; McGrail, B. P.; Schaef, T.

    2014-12-01

    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 a Na-saturated montmorillonite (Na-SWy-2) in high-pressure (90 bar) and moderate temperature (50 °C) methane and mixtures of methane and carbon dioxide were investigated usingCH4 IR spectroscopic titrations andCH4 XRD. The goals were to (1) determine if the hydration/expansion behavior of the clay in supercritical methane is different than in supercritical CO2, (2) determine if methane intercalates the clay, and (3) probe the effects of increasing CO2 concentrations. IR spectra were collected as Na-SWy-2 was titrated with water under several fluid exposures: pure methane, 25, 50, and 75 mole% CO2 in methane, and pure CO2. ComplementaryCH4 XRD experiments were conducted in the same fluids at discrete dissolved water concentrations to measure the d001 values of the clay and thus its volume change on hydration and CH4 and/or CO2 intercalation. In pure methane, no direct evidence of CH4 intercalation was detected in CH bending or stretching regions of the IR spectra. Similarly, in situ XRD indicated the montmorillonite structure was stable in the presence of CH4 and no measurable changes to the basal spacing were observed. However, under low water conditions where the montmorillonite structure was partially expanded (~sub 1W), the IR data indicated a rapid intercalation of CO2 into the interlayer, even with fluid mixtures containing the

  14. High-power ultrasonic system for the enhancement of mass transfer in supercritical CO2 extraction processes.

    PubMed

    Riera, Enrique; Blanco, Alfonso; García, José; Benedito, José; Mulet, Antonio; Gallego-Juárez, Juan A; Blasco, Miguel

    2010-02-01

    Oil is an important component of almonds and other vegetable substrates that can show an influence on human health. In this work the development and validation of an innovative, robust, stable, reliable and efficient ultrasonic system at pilot scale to assist supercritical CO(2) extraction of oils from different substrates is presented. In the extraction procedure ultrasonic energy represents an efficient way of producing deep agitation enhancing mass transfer processes because of some mechanisms (radiation pressure, streaming, agitation, high amplitude vibrations, etc.). A previous work to this research pointed out the feasibility of integrating an ultrasonic field inside a supercritical extractor without losing a significant volume fraction. This pioneer method enabled to accelerate mass transfer and then, improving supercritical extraction times. To commercially develop the new procedure fulfilling industrial requirements, a new configuration device has been designed, implemented, tested and successfully validated for supercritical fluid extraction of oil from different vegetable substrates.

  15. 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.

  16. 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

  17. Behavior of water in supercritical CO2: adsorption and capillary condensation in porous media

    NASA Astrophysics Data System (ADS)

    Heath, J. E.; Bryan, C. R.; Dewers, T. A.; Wang, Y.

    2011-12-01

    The chemical potential of water in supercritical CO2 (scCO2) may play an important role in water adsorption, capillary condensation, and evaporation under partially saturated conditions at geologic CO2 storage sites, especially if initially anhydrous CO2 is injected. Such processes may affect residual water saturations, relative permeability, shrink/swell of clays, and colloidal transport. We have developed a thermodynamic model of water or brine film thickness as a function of water relative humidity in scCO2. The model is based on investigations of liquid water configuration in the vadose zone and uses the augmented Young-Laplace equation, which incorporates both adsorptive and capillary components. The adsorptive component is based on the concept of disjoining pressure, which reflects force per area normal to the solid and water/brine-scCO2 interfaces. The disjoining pressure includes van der Waals, electrostatic, and structural interactions. The van der Waals term includes the effects of mutual dissolution of CO2 and water in the two fluid phases on partial molar volumes, dielectric coefficients, and refractive indices. Our approach treats the two interfaces as asymmetric surfaces in terms of charge densities and electrostatic potentials. We use the disjoining pressure isotherm to evaluate the type of wetting (e.g., total or partial wetting) for common reservoir and caprock minerals and kerogen. The capillary component incorporates water activity and is applied to simple pore geometries with slits and corners. Finally, we compare results of the model to a companion study by the coauthors on measurement of water adsorption to mineral phases using a quartz-crystal microbalance. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  18. 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.

  19. Applications of supercritical CO2 in the fabrication of polymer systems for drug delivery and tissue engineering.

    PubMed

    Davies, Owen R; Lewis, Andrew L; Whitaker, Martin J; Tai, Hongyun; Shakesheff, Kevin M; Howdle, Steven M

    2008-02-14

    Supercritical CO(2) has the potential to be an excellent environment within which controlled release polymers and dry composites may be formed. The low temperature and dry conditions within the fluid offer obvious advantages in the processing of water, solvent or heat labile molecules. The low viscosity and high diffusivity of scCO(2) offer the possibility of novel processing routes for polymer drug composites, but there are still technical challenges to overcome. Moreover, the low solubility of most drug molecules in scCO(2) presents both challenges and advantages. This review explores the current methods that use high pressure and scCO(2) for the production of drug delivery systems and the more specialized application of the fluid in the formation of highly porous tissue engineering scaffolds.

  20. Biocatalytic Processing Polymers in Supercritical Fluids

    DTIC Science & Technology

    1994-01-01

    Russell, A.J and Beckman, E.J. (1991) Appl. Bioch . Biotech., 31, 197-211. Enzyme activity in supercritical fluids. 22. *Russell, A.J and Beckman, E.J...S., Jacob , J., Beckman, E.J. and Russell, A.J. (1991) Enz. Microb. Technol., 13, 519. Biocatalytic synthesis of acrylates in supercritical fluids. 24

  1. Preparation of drug delivery systems using supercritical fluid technology.

    PubMed

    Kompella, U B; Koushik, K

    2001-01-01

    Small changes in temperature and pressure near the critical region induce dramatic changes in the density and solubility of supercritical fluids, thereby facilitating the use of environmentally benign agents such as CO2 for their solvent and antisolvent properties in processing a wide variety of materials. While supercritical fluid technologies have been in commercial use in the food and chromatography industries for several years, only recently has this technology made inroads in the formulation of drug delivery systems. This review summarizes some of the recent applications of supercritical fluid technology in the preparation of drug delivery systems. Drugs containing polymeric particles, plain drug particles, solute-containing liposomes, and inclusion complexes of drug and carrier have been formulated using this technology. Also, polymer separation using this technology is enabling the selection of a pure fraction of a polymer, thereby allowing a more precise control of drug release from polymeric delivery systems.

  2. 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

  3. 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.

  4. The interaction between Hontomín shale and CO2-rich brine under supercritical CO2 conditions. Percolation experiments

    NASA Astrophysics Data System (ADS)

    Dávila, Gabriela; Cama, Jordi; Luquot, Linda; Soler, Josep

    2014-05-01

    Geological CO2 sequestration at a pilot-plant scale is going to be performed at Hontomín (Spain). The main caprock is made up of marly shales, with an average composition (wt.%) of 56% calcite, 21% quartz, 17% illite, 3% clinochlore and albite and trace amounts of pyrite, gypsum and anhydrite. The reservoir brine is rich in NaCl and sulfate (I = 0.6 M) and equilibrated with respect to gypsum/anhydrite and calcite. The present study aims at evaluating the interaction between the shale and the CO2-rich brine of Hontomín by performing (1) laboratory experiments and (2) 2D reactive transport modeling. (1) Laboratory experiments: percolation experiments with artificially fractured cores (7.5 mm in diameter and 18 mm in length) under supercritical CO2 conditions (pTotal = 150 bar, pCO2 from 82 to 95 bar, T = 60 °C) are carried out to evaluate and quantify the influence of mineral dissolution/precipitation processes on fracture permeability. Two synthetic CO2-rich brines, sulfate-free and sulfate-rich brines with similar composition to that of Hontomín, circulate at constant flow rate (0.2, 1 and 60 mL h-1) through the fracture. Under supercritical pCO2 the acid brine acidic (pH ~3) reacts with the shale and induces significant dissolution of calcite and aluminosilicates (mainly, chlorite and albite). (2) 2D reactive transport modeling: CrunchFlow is utilized to match the observed variation with time of the aqueous concentrations of Ca, Si and sulfate and pH during the fracture-CO2-rich brine interaction under supercritical pCO2 conditions. Evaluation of the kinetic parameters, such as the values of the mineral surface area, will be performed. Solute transport is dominated by advection along the fracture and by diffusion through the rock matrix. This type of simulations is the basis for a prediction of the magnitude of the geochemical processes during the caprock-brine interaction at Hontomín under supercritical CO2 conditions. Acknowledgements This study was

  5. 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

  6. Chemical Processes with Supercritical CO2 in Engineered Geologic Systems: Significance, Previous Study, and Path Forward (Invited)

    NASA Astrophysics Data System (ADS)

    Xu, T.; Pruess, K.

    2009-12-01

    Chemical reactions with dissolved CO2 in the aqueous phase have long been considered in fundamental geosciences and practical applications. Recently, studies on geologic carbon sequestration and enhanced geothermal systems using CO2 as heat transmission fluid have brought new interests in chemical reaction processes directly with supercritical CO2 (scCO2, or gas phase). In the vicinity of a CO2 injection well, the aqueous fluid initially present in a geological formation would be quickly removed by dissolution (evaporation) into the flowing gas stream and by immiscible displacement by the scCO2, creating a gas phase dominant zone. In this zone, the water evaporation could cause formation dry-out and precipitation of salt near the injection well, reducing formation porosity, permeability, and injectivity. The scCO2 may directly attack well construction materials such as cement. Over time, the gas phase will tend to migrate upwards towards the caprock because the density of the scCO2 is lower than that of the aqueous phase. In the upper portions of the reservoir, the scCO2 will directly react with caprock minerals and alter the hydrological properties and mechanical strength. On the other hand, the scCO2 phase will maintain the dissolution into the aqueous phase, lowering pH, inducing mineral dissolution, complexing with dissolved cations, increasing CO2 solubility, increasing the density of the aqueous phase, and promoting “convective mixing”. Chemical processes are quite different in the scCO2 dominant geologic systems. The absence of an aqueous phase poses unique questions, as little is presently known about the chemistry of non-aqueous systems. Additional issues arise from the reactivity of water that is dissolved in the ScCO2 phase. In this presentation, the author will discuss the importance, state of the studies performed, and future research directions.

  7. 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.

  8. Experimental Performance Analysis of Supercritical CO2 Thermodynamic Cycle Powered by Solar Energy

    NASA Astrophysics Data System (ADS)

    Zhang, X. R.; Yamaguchi, H.; Fujima, K.; Enomoto, M.; Sawada, N.

    2006-05-01

    The interests in using carbon dioxide as working fluid increase since the Montreal and Kyoto Protocols were made. In this paper, a complete effort was made to study the performance of CO2 Rankine cycle powered by solar energy experimentally. The system utilizes evacuated solar collectors to convert CO2 into high-temperature supercritical state, used to produce electrical energy and thermal energy, which could be used for air conditioning and hot water supply and so on. The system performances were tested not only in summer, but also in winter; not only in sunny day, but also in cloudy day. The interest of the paper is the solar collector efficiency, because the absorbed heat quantity in the collector can be utilized for power generation and heat supply and other useful outputs. The results show that annually-averaged solar collector efficiency was measured at about 60.4%. The study shows the potential of the application of the solar powered CO2 cycle as a distributed power/heat generation system.

  9. Relative permeabilities of supercritical CO2 and brine in carbon sequestration by a two-phase lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Xie, Jian.-Fei.; He, S.; Zu, Y. Q.; Lamy-Chappuis, B.; Yardley, B. W. D.

    2017-03-01

    In this paper, the migration of supercritical carbon dioxide (CO2 ) in realistic sandstone rocks under conditions of saline aquifers, with applications to the carbon geological storage, has been investigated by a two-phase lattice Boltzmann method (LBM). Firstly the digital images of sandstone rocks were reproduced utilizing the X-ray computed microtomography (micro-CT), and high resolutions (up to 2.5 μm) were applied to the pore-scale LBM simulations. For the sake of numerical stability, the digital images were "cleaned" by closing the dead holes and removing the suspended particles in sandstone rocks. In addition, the effect of chemical reactions occurred in the carbonation process on the permeability was taken into account. For the wetting brine and non-wetting supercritical CO2 flows, they were treated as the immiscible fluids and were driven by pressure gradients in sandstone rocks. Relative permeabilities of brine and supercritical CO2 in sandstone rocks were estimated. Particularly the dynamic saturation was applied to improve the reliability of the calculations of the relative permeabilities. Moreover, the effects of the viscosity ratio of the two immiscible fluids and the resolution of digital images on the relative permeability were systematically investigated.

  10. 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

  11. 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.

  12. Use and practice of achiral and chiral supercritical fluid chromatography in pharmaceutical analysis and purification.

    PubMed

    Lemasson, Elise; Bertin, Sophie; West, Caroline

    2016-01-01

    The interest of pharmaceutical companies for complementary high-performance chromatographic tools to assess a product's purity or enhance this purity is on the rise. The high-throughput capability and economic benefits of supercritical fluid chromatography, but also the "green" aspect of CO2 as the principal solvent, render supercritical fluid chromatography very attractive for a wide range of pharmaceutical applications. The recent reintroduction of new robust instruments dedicated to supercritical fluid chromatography and the progress in stationary phase technology have also greatly benefited supercritical fluid chromatography. Additionally, it was shown several times that supercritical fluid chromatography could be orthogonal to reversed-phase high-performance liquid chromatography and could efficiently compete with it. Supercritical fluid chromatography is an adequate tool for small molecules of pharmaceutical interest: synthetic intermediates, active pharmaceutical ingredients, impurities, or degradation products. In this review, we first discuss about general chromatographic conditions for supercritical fluid chromatography analysis to better suit compounds of pharmaceutical interest. We also discuss about the use of achiral and chiral supercritical fluid chromatography for analytical purposes and the recent applications in these areas. The use of preparative supercritical fluid chromatography by pharmaceutical companies is also covered.

  13. 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).

  14. Nanostructured Materials: Symthesis in Supercritical Fluids

    SciTech Connect

    Lin, Yuehe; Ye, Xiangrong; Wai, Chien M.

    2009-03-24

    This chapter summarizes the recent developent of synthesis and characterization of nanostructured materials synthesized in supercritical fluids. Nanocomposite catalysts such as Pt and Pd on carbon nanotube support have been synthesized and used for fuel cell applications.

  15. Combination of supercritical CO2 and vacuum distillation for the fractionation of bergamot oil.

    PubMed

    Fang, Tao; Goto, Motonobu; Sasaki, Mitsuru; Hirose, Tsutomu

    2004-08-11

    Supercritical CO2 can be used to separate oxygenated compounds from essential oils. This technique still cannot replace vacuum distillation as an industrial process because of low recoveries and inconsistent results. In the present work, a comparison between the two methods was made in terms of composition, recovery, and color. Vacuum distillation and supercritical CO2 are complementary processes for producing high quality oxygenated compounds with high recovery rates. The former is more suitable for removing monoterpenes at low fraction temperatures (< or =308 K), and the latter is more suitable for separating oxygenated compounds from pigments and waxes. Consequently, the two methods were combined. For supercritical CO2 fractionation, the parameters of pressure, temperature gradient, and the ratio of solvent to feed were investigated for the fractionation of oxygenated compounds with high recoveries (> or =85%) and without other macromolecules, such as pigments and waxes.

  16. New topic of supercritical fluids: Local activity coefficients of supercritical solvent and cosolvent around solute

    NASA Astrophysics Data System (ADS)

    Hou, Minqiang; Zhang, Xiaogang; Han, Buxing; Song, Jiyuan; Liu, Gang; Zhang, Zhaofu; Zhang, Jianling

    2008-03-01

    The study of inhomogeneity in supercritical fluids (SCFs) is of great importance. In this work, we propose the concept of local activity coefficients in supercritical (SC) solutions, which link thermodynamics and inhomogeneity in SC systems. The local activity coefficients of CO2+acetonitrile+phenol blue and CO2+aceticacid+phenol blue systems are investigated at 308.15K in critical region and outside critical region. To do this, the local compositions of CO2+acetonitrile and CO2+acetic acid mixed solvents around phenol blue are first estimated using UV-visible spectroscopy. Then it is considered that there exist bulk phase and local phase around phenol blue in the systems. The activity coefficients of CO2 and the cosolvents (acetonitrile or acetic acid) in bulk phase are calculated using Peng-Robinson equation of state. The local activity coefficients of CO2 and the cosolvents are then calculated on the basis of thermodynamic principles. It is demonstrated that in the critical region the local activity coefficients differ from bulk activity coefficients significantly and are sensitive to pressure. This can explain many unusual phenomena in SC systems in critical region thermodynamically.

  17. New topic of supercritical fluids: local activity coefficients of supercritical solvent and cosolvent around solute.

    PubMed

    Hou, Minqiang; Zhang, Xiaogang; Han, Buxing; Song, Jiyuan; Liu, Gang; Zhang, Zhaofu; Zhang, Jianling

    2008-03-14

    The study of inhomogeneity in supercritical fluids (SCFs) is of great importance. In this work, we propose the concept of local activity coefficients in supercritical (SC) solutions, which link thermodynamics and inhomogeneity in SC systems. The local activity coefficients of CO(2)+acetonitrile+phenol blue and CO(2)+acetic acid+phenol blue systems are investigated at 308.15 K in critical region and outside critical region. To do this, the local compositions of CO(2)+acetonitrile and CO(2)+acetic acid mixed solvents around phenol blue are first estimated using UV-visible spectroscopy. Then it is considered that there exist bulk phase and local phase around phenol blue in the systems. The activity coefficients of CO(2) and the cosolvents (acetonitrile or acetic acid) in bulk phase are calculated using Peng-Robinson equation of state. The local activity coefficients of CO(2) and the cosolvents are then calculated on the basis of thermodynamic principles. It is demonstrated that in the critical region the local activity coefficients differ from bulk activity coefficients significantly and are sensitive to pressure. This can explain many unusual phenomena in SC systems in critical region thermodynamically.

  18. 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

    2015-01-06

    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.

  19. 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 A; Rochau, Gary E; 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.

  20. 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.

  1. 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.

  2. 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

  3. 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)

  4. Oxy-combustor operable with supercritical fluid

    DOEpatents

    Brun, Klaus; McClung, Aaron M.; Owston, Rebecca A.

    2017-04-04

    An oxy-combustor is provided which comprises a combustion vessel including at least one solid fuel slurry inlet port, at least one oxygen inlet port and at least one supercritical fluid inlet port, wherein the combustion vessel is operable at an operating pressure of at least 1,100 psi; an interior of the combustion vessel comprises a combustion chamber and a supercritical fluid infusion chamber surrounding at least a part of the combustion chamber, the supercritical fluid infusion chamber and the combustion chamber are separated by a porous liner surrounding the combustion chamber, and the supercritical infusion chamber is located between the porous liner and an outer casing of the combustion vessel.

  5. 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

    2012-05-08

    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.

  6. 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.

  7. Water extractable arabinoxylan aerogels prepared by supercritical CO2 drying.

    PubMed

    Marquez-Escalante, Jorge; Carvajal-Millan, Elizabeth; Miki-Yoshida, Mario; Alvarez-Contreras, Lorena; Toledo-Guillén, Alma Rosa; Lizardi-Mendoza, Jaime; Rascón-Chu, Agustín

    2013-05-14

    Water extractable arabinoxylan (WEAX) aerogels were prepared by extracting the solvent from the alcogels (WEAX hydrogels with an alcohol as the solvent) with carbon dioxide under supercritical conditions. WEAX aerogels were characterized using scanning electron microscopy and adsorption and desorption nitrogen isotherms. The micrographs indicate a heterogeneous porous network structure in WEAX aerogel. Adsorption/desorption nitrogen isotherms of this material were type IV, which confirm that this material possess a mesoporous structure. WEAX aerogels rehydration capability was evaluated and the water absorption mechanism was determined. The WEAX aerogels water absorption mechanism was non-Fickian (n = 0.54).

  8. Supercritical fluid chromatography for lipid analysis in foodstuffs.

    PubMed

    Donato, Paola; Inferrera, Veronica; Sciarrone, Danilo; Mondello, Luigi

    2017-01-01

    The task of lipid analysis has always challenged separation scientists, and new techniques in chromatography were often developed for the separation of lipids; however, no single technique or methodology is yet capable of affording a comprehensive screening of all lipid species and classes. This review acquaints the role of supercritical fluid chromatography within the field of lipid analysis, from the early developed capillary separations based on pure CO2 , to the most recent techniques employing packed columns under subcritical conditions, including the niche multidimensional techniques using supercritical fluids in at least one of the separation dimensions. A short history of supercritical fluid chromatography will be introduced first, from its early popularity in the late 1980s, to the sudden fall and oblivion until the last decade, experiencing a regain of interest within the chromatographic community. Afterwards, the subject of lipid nomenclature and classification will be briefly dealt with, before discussing the main applications of supercritical fluid chromatography for food analysis, according to the specific class of lipids.

  9. 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

    2013-01-02

    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.

  10. Swelling-induced changes in coal microstructure due to supercritical CO2 injection

    NASA Astrophysics Data System (ADS)

    Zhang, Yihuai; Lebedev, Maxim; Sarmadivaleh, Mohammad; Barifcani, Ahmed; Iglauer, Stefan

    2016-09-01

    Enhanced coalbed methane recovery and CO2 geostorage in coal seams are severely limited by permeability decrease caused by CO2 injection and associated coal matrix swelling. Typically, it is assumed that matrix swelling leads to coal cleat closure, and as a consequence, permeability is reduced. However, this assumption has not yet been directly observed. Using a novel in situ reservoir condition X-ray microcomputed tomography flooding apparatus, for the first time we observed such microcleat closure induced by supercritical CO2 flooding in situ. Furthermore, fracturing of the mineral phase (embedded in the coal) was observed; this fracturing was induced by the internal swelling stress. We conclude that coal permeability is drastically reduced by cleat closure, which again is caused by coal matrix swelling, which again is caused by flooding with supercritical CO2.

  11. The Role of H2O in Brucite-Supercritical CO2 Reaction: Relevance to CO2 Sequestration

    NASA Astrophysics Data System (ADS)

    Dong, S.; Zhao, L.; Chen, Z.; Teng, H.

    2013-12-01

    It is widely recognized that the presence of water is vital for brucite carbonation in supercritical CO2 (scCO2) based upon the observation that nesquehonite (MgCO3`3H2O) precipitated instantly in brucite-water-scCO2 system while no carbonate was detected in brucite-scCO2 medium. The importance of water is further emphasized by the result that shows higher water concentrations led to greater carbonation rates. However, the mechanism of water effect is not fully understood as two possible pathways exist for the carbonation reaction: 1) the dissociation of H2O provides a) H+ to release Mg2+ through associating with OH- in brucite, and b) OH- to combine with CO2 to form HCO3-, leading to the interaction of magnesium cations with carbonate anions; 2) H2O molecules polarizes CO2 through hydrogen bonding to promote direct interactions between carbon dioxide and brucite followed by water release from Mg(OH)2. The present study attempts to determine whether proton-effect or polarity-effect is the governing force for brucite carbonation in scCO2 - H2O system. Experiments were carried out in water-saturated scCO2 (experimental H2O mole fraction in CO2 is 4.1×10-2, solubility of H2O in CO2 at experimental condition is 3.5×10-3), and formamide (FM, HCONH2)-saturated scCO2 (experimental FM mole fraction in CO2 is 1.8×10-2), at 50 oC temperature and 8MPa pressure. Formamide was selected because of its similar permittivity to water (ɛH2O,20oC=80.1, ɛHCONH2,20oC=84.0) but the lack of proton-donating ability. In situ Raman spectroscopy data revealed that nesquehonite and hydromagnesite (Mg5(CO3)4(OH)2`4H2O, minor quantity) formed in both brucite-water-scCO2 and brucite-FM-scCO2 systems but at a different rate, with the former within 5h and the latter 45h to reach similar carbonation extent. While this result cannot completely rule out the role of water as brucite may dehydrate in FM, it shows that liquid water may not be needed for mineral-scCO2 interaction as long as the

  12. 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.

  13. 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.

  14. Ampicillin Nanoparticles Production via Supercritical CO2 Gas Antisolvent Process.

    PubMed

    Esfandiari, Nadia; Ghoreishi, Seyyed M

    2015-12-01

    The micronization of ampicillin via supercritical gas antisolvent (GAS) process was studied. The particle size distribution was significantly controlled with effective GAS variables such as initial solute concentration, temperature, pressure, and antisolvent addition rate. The effect of each variable in three levels was investigated. The precipitated particles were analyzed with scanning electron microscopy (SEM) and Zetasizer Nano ZS. The results indicated that decreasing the temperature and initial solute concentration while increasing the antisolvent rate and pressure led to a decrease in ampicillin particle size. The mean particle size of ampicillin was obtained in the range of 220-430 nm by varying the GAS effective variables. The purity of GAS-synthesized ampicillin nanoparticles was analyzed in contrast to unprocessed ampicillin by FTIR and HPLC. The results indicated that the structure of the ampicillin nanoparticles remained unchanged during the GAS process.

  15. Wettability effect on capillary trapping of supercritical CO2 at pore-scale: micromodel experiment and numerical modeling

    NASA Astrophysics Data System (ADS)

    Hu, R.; Wan, J.

    2015-12-01

    Wettability of reservoir minerals along pore surfaces plays a controlling role in capillary trapping of supercritical (sc) CO2 in geologic carbon sequestration. The mechanisms controlling scCO2 residual trapping are still not fully understood. We studied the effect of pore surface wettability on CO2 residual saturation at the pore-scale using engineered high pressure and high temperature micromodel (transparent pore networks) experiments and numerical modeling. Through chemical treatment of the micromodel pore surfaces, water-wet, intermediate-wet, and CO2-wet micromodels can be obtained. Both drainage and imbibition experiments were conducted at 8.5 MPa and 45 °C with controlled flow rate. Dynamic images of fluid-fluid displacement processes were recorded using a microscope with a CCD camera. Residual saturations were determined by analysis of late stage imbibition images of flow path structures. We performed direct numerical simulations of the full Navier-Stokes equations using a volume-of-fluid based finite-volume framework for the primary drainage and the followed imbibition for the micromodel experiments with different contact angles. The numerical simulations agreed well with our experimental observations. We found that more scCO2 can be trapped within the CO2-wet micromodel whereas lower residual scCO2 saturation occurred within the water-wet micromodels in both our experiments and the numerical simulations. These results provide direct and consistent evidence of the effect of wettability, and have important implications for scCO2 trapping in geologic carbon sequestration.

  16. 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.

  17. Supercritical fluid reactions for coal processing

    SciTech Connect

    Eckert, C.A.

    1997-04-01

    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 has been previously collected for pure CO{sub 2} at pressures between the critical pressure of CO{sub 2} (73.8 bar) and 216 bar. This data is 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.

  18. 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.

  19. Thermochromic shifts in supercritical fluids

    SciTech Connect

    Yonker, C.R.; Smith, R.D. )

    1989-02-23

    Thermochromic shifts of organic solute molecules in supercritical CO{sub 2} under conditions of both constant pressure and density are compared to previous studies of solvatochromic shifts at isothermal conditions. Similar solvatochromic and thermochromic shifts are seen as a function of density for supercritical CO{sub 2}. At constant density a small thermochromic shift ({approx}400 cm{sup {minus}1}) for supercritical CO{sub 2} was seen for both 2-nitroanisole and 4-ethylnitrobenzene. The excited-state dipole moments for 2-nitroanisole, as calculated from the thermochromic and solvatochromic data, were in agreement.

  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. Swelled plastics in supercritical CO2 as media for stabilization of metal nanoparticles and for catalytic hydrogenation.

    PubMed

    Ohde, Hiroyuki; Ohde, Mariko; Wai, Chien M

    2004-04-21

    Swelled plastics in supercritical carbon dioxide provide unique environments for stabilizing palladium and rhodium nanoparticles and for catalytic hydrogenation. Complete hydrogenation of benzene to cyclohexane can be achieved in 10 minutes using the plastic stabilized Rh nanoparticles at 50 degrees C in supercritical CO(2). High efficiency, reusability, and rapid separation of products are some advantages of the plastic stabilized metal nanoparticles for catalytic hydrogenation in supercritical CO(2).

  2. 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

  3. 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.

  4. Shape transitions in supercritical CO2 microemulsions induced by hydrotropes.

    PubMed

    James, Craig; Hatzopoulos, Marios Hopkins; Yan, Ci; Smith, Gregory N; Alexander, Shirin; Rogers, Sarah E; Eastoe, Julian

    2014-01-14

    The ability to induce morphological transitions in water-in-oil (w/o) and water-in-CO2 (w/c) microemulsions stabilized by a trichain anionic surfactant 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-sulfonate (TC14) with simple hydrotrope additives has been investigated. High-pressure small-angle neutron scattering (SANS) has revealed the addition of a small mole fraction of hydrotrope can yield a significant elongation in the microemulsion water droplets. For w/o systems, the degree of droplet growth was shown to be dependent on the water content, the hydrotrope mole fraction, and chemical structure, whereas for w/c microemulsions a similar, but less significant, effect was seen. The expected CO2 viscosity increase from such systems has been calculated and compared to related literature using fluorocarbon chain surfactants. This represents the first report of hydrotrope-induced morphology changes in w/c microemulsions and is a significant step forward toward the formation of hydrocarbon worm-like micellar assemblies in this industrially relevant solvent.

  5. Structural features of binary mixtures of supercritical CO2 with polar entrainers by molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    Gurina, D. L.; Antipova, M. L.; Petrenko, V. E.

    2013-10-01

    Computer simulations of supercritical carbon dioxide and its mixtures with polar cosolvents: water, methanol, and ethanol (concentration, 0.125 mole fractions) at T = 318 K and ρ = 0.7 g/cm3 are performed. Atom-atom radial distribution functions are calculated by classical molecular dynamics, while the probability distributions of relative orientation of CO2 molecules in the first and second coordination spheres describing the geometry of the nearest environment of CO2 molecules and the trajectories of cosolvent molecules are found using Car-Parrinello molecular dynamics. Based on the latter, the conclusions regarding structure and interactions of polar entrainers in their mixtures with supercritical CO2 are made. It is shown that the microstructure of carbon dioxide varies only slightly upon the introduction of cosolvents.

  6. 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.

  7. 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

  8. 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).

  9. Viral inactivation of human bone tissue using supercritical fluid extraction.

    PubMed

    Fages, J; Poirier, B; Barbier, Y; Frayssinet, P; Joffret, M L; Majewski, W; Bonel, G; Larzul, D

    1998-01-01

    A new bone tissue process using supercritical carbon dioxide fluid extraction (SFE) has been evaluated for its ability to inactivate or eliminate viruses. Four viruses, human immunodeficiency virus type 1 (HIV-1), Sindbis virus, polio Sabin type I virus, and pseudorabies virus (PRV), were exposed to four different processing steps. In addition to supercritical CO2, hydrogen peroxide, sodium hydroxide, and ethanol treatments were evaluated. The mean cumulated reduction factors (log10) for the four viruses exposed to these four steps were > 14.2 for HIV-1, > 18.2 for Sindbis virus, > 24.4 for poliovirus, and > 17.6 for PRV. The mean reduction factors obtained by the supercritical fluid extraction alone were > 4.0, > 4.3, > 6.6, and > 4.0, respectively. These results demonstrate that the SFE process is effective in inactivating viruses on human femoral heads, and provides a level of inactivation similar to that obtained by traditional cleaning methods. It is proposed that CO2 SFE be incorporated as a routine step in the processing of bone allografts for transplantation either to replace or supplement existing procedures.

  10. 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.

  11. Investigation of the Properties of Pore-Confined Supercritical CO2 by Vibrating Tube and Gravimetric Adsorption Methods

    NASA Astrophysics Data System (ADS)

    Gruszkiewicz, M. S.; Rother, G.; Wesolowski, D. J.; Cole, D. R.

    2011-12-01

    Accurate properties of multicomponent CO2-rich fluids are needed to understand and control the processes occurring during subsurface storage of CO2, enhanced coalbed methane recovery, and proposed geothermal heat mining using CO2 instead of water. While fluid transport in macroscopic fractures is mainly affected by bulk fluid properties, mineral dissolution and fluid-rock reactions occur at the solid-fluid interface located largely in mesopore and micropore networks. Densities, mineral solubilities, ionic and phase equilibria, and transport properties of multicomponent fluids change significantly in close proximity to mineral surfaces. Accurate modeling of the behavior of CO2-rich fluids and their effect on the evolution of the reservoir and caprock permeability depend on accurate properties of both bulk and confined phases. Although manometric, volumetric, and gravimetric techniques have been used successfully to investigate adsorption of low-density subcritical gases and vapors, they are not capable of complete characterization of interfacial processes at higher, liquid-like densities of supercritical fluids. As the density of bulk fluid becomes comparable to that of the pore fluid, excess adsorption is no longer a good estimate of total adsorption capacity of the formation and the properties of the pore fluid remain unknown. In this work vibrating tube densimetry of pore fluids was used for the first time as a novel method capable of providing the total amount of fluid contained within a pore system through a direct measurement of the mass of a fluid-saturated porous solid. The method is first demonstrated using propane at subcritical and supercritical temperatures between 35 °C and 97 °C confined in silica aerogel (density 0.2 g/cm3, porosity 90%) that was synthesized inside Hastelloy U-tubes. Sorption and desorption of carbon dioxide on the same solid was measured between 31 °C ( the critical temperature of CO2) and 50 °C at pressures to 140 bar (density

  12. 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

  13. Carotenoids extraction from Japanese persimmon (Hachiya-kaki) peels by supercritical CO(2) with ethanol.

    PubMed

    Takahashi, Mayako; Watanabe, Hiromoto; Kikkawa, Junko; Ota, Masaki; Watanabe, Masaru; Sato, Yoshiyuki; Inomata, Hiroshi; Sato, Nobuyuki

    2006-11-01

    The extraction of carotenoids from Japanese persimmon peels by supercritical fluid extraction (SFE), of which the solvent was CO(2), was performed. In order to enhance the yield and selectivity of the extraction, some portion of ethanol (5 - 20 mol%) was added as an entrainer. The extraction temperature ranged from 313 to 353 K and the pressure was 30 MPa. The effect of temperature on the extraction yield of carotenoids was investigated at 10 mol% of the ethanol concentration in the extraction solvent, and a suitable temperature was found to be 333 K among the temperatures studied with respect to the carotenoid yield. With increasing the entrainer amount from 0 to 10 mol% at a constant temperature (333 K), the carotenoid yield in the extraction was improved, whereas the selectivity of the extracted carotenoids was drastically depressed. We also conducted qualitative and quantitative analyses for the carotenoid components in the extract by HPLC, and analyzed the extraction behavior of each individual carotenoid (alpha-carotene, beta-carotene, beta-cryptoxanthin, lycopene, lutein, and zeaxanthin). The selectivity of each carotenoid changed with the elapsed time and its time evolution was dependent on the carotenoid component, indicating that the location profile and the content can be important factors to understand the SFE behavior of each carotenoid in persimmon peels.

  14. 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.

  15. 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

  16. Effects of Reservoir Depth and Brine Composition on the Hydrodynamic Instabilities and Dissolution of Supercritical CO2 Releases in the Subsurface

    NASA Astrophysics Data System (ADS)

    Burton, E.; Ezzedine, S. M.

    2009-12-01

    CO2 injected into deep brine formation will be mainly present in three forms: 1) a dense supercritical gas phase, 2) a dissolved state in pore water and 3) an immobilized state through geochemical reaction with in-situ minerals. The lower density of the stored supercritical CO2 will cause buoyant flow of CO2 to the top of the injection zone below the caprock. The integrity of the caprock (no fault activation or fissure formation) is critical to CO2 sequestration and a more complete study of caprock leakage is needed to provide a full understanding of the process and its implication for CO2 sequestration. The flow depends on the density difference as well as the vertical and horizontal permeability of the formation. The very low viscosity of the supercritical CO2 will give rise to instabilities at the CO2-brine interface as CO2 is being injected into the formation, which results in fingering. Nonlinear interactions of chemical reactions and viscous fingering of a low (high) viscosity slice of fluid displaced by a higher (lower) viscosity fluid is studied in porous media by direct numerical simulations of Darcy’s law coupled to the evolution equation for the concentration of a chemically reacting solute controlling the viscosity and density solutions. Chemical kinetics introduces important topological changes in the fingering pattern formation mechanisms such as snap-off, splitting and formation of small ganglia of CO2 which enhance the dissolution of CO2 into the brine. Spatial moment analyses are conducted to assess transient fingering contribution to the increase of breakthrough time variance through a suite of physical parameters such as geological formation depth, mobility ratios, dispersion anisotropy and different brine compositions.

  17. 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

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

    SciTech Connect

    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-analogue 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

  19. 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.

  20. 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.

  1. 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.

  2. 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...

  3. 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.

  4. Mechanism of Bacillus subtilis Spore Inactivation by and Resistance to Supercritical CO2 plus Peracetic Acid

    PubMed Central

    Setlow, Barbara; Korza, George; Blatt, Kelly M.S.; Fey, Julien P.; Setlow, Peter

    2015-01-01

    Aims Determine how supercritical CO2 (scCO2) plus peracetic acid (PAA) inactivates Bacillus subtilis spores, factors important in spore resistance to scCO2-PAA, and if spores inactivated by scCO2-PAA are truly dead. Methods and Results Spores of wild-type B. subtilis and isogenic mutants lacking spore protective proteins were treated with scCO2-PAA in liquid or dry at 35°C. Wild-type wet spores (aqueous suspension) were more susceptible than dry spores. Treated spores were examined for viability (and were truly dead), dipicolinic acid (DPA), mutations, permeability to nucleic acid stains, germination under different conditions, energy metabolism and outgrowth. ScCO2-PAA-inactivated spores retained DPA, and survivors had no notable DNA damage. However, DPA was released from inactivated spores at a normally innocuous temperature (85°C), and colony formation from treated spores was salt sensitive. The inactivated spores germinated but did not outgrow, and these germinated spores had altered plasma membrane permeability and defective energy metabolism. Wet or dry coat-defective spores had increased scCO2-PAA sensitivity, and dry spores but not wet spores lacking DNA protective proteins were more scCO2-PAA sensitive. Conclusions These findings suggest that scCO2-PAA inactivates spores by damaging spores’ inner membrane. The spore coat provided scCO2-PAA resistance for both wet and dry spores. DNA protective proteins provided scCO2-PAA resistance only for dry spores. Significance and Impact of Study These results provide information on mechanisms of spore inactivation of and resistance to scCO2-PAA, an agent with increasing use in sterilization applications. PMID:26535794

  5. Analytical supercritical fluid extraction of adsorbent materials

    SciTech Connect

    Wright, B.W.; Wright, C.W.; Gale, R.W.; Smith, R.D.

    1987-01-01

    The use of supercritical fluids for the analytical extraction of semivolatile and higher molecular weight materials from various adsorbent and particulate matrices was investigated. Instrumentation was designed to allow gram quantities of the matrix to be extracted at pressures up to 400 bar and temperatures to 235 /sup 0/C with collection of the effluent in a sealed liquid-nitrogen-cooled flask. Carbon dioxide, isobutane, and methanol modified (20 mol %) carbon dioxide fluid systems were evaluated and compared to liquid Soxhlet extraction. Supercritical fluid extraction (SFE) provided very rapid (approx. =30 min) extraction with comparable efficiency to the Soxhlet methods, and both more rapid and more efficient extractions appear feasible. The more polar carbon dioxide-methanol fluid system gave higher extraction efficiencies for the more polar adsorbates and the isobutane system was more efficient for the higher molecular weight and less polar compounds.

  6. 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.

  7. [Optimization of supercritical fluid extraction of bioactive components in Ligusticum chuanxiong by orthogonal array design].

    PubMed

    Hu, Li-Cui; Wu, Xun; Yang, Xue-Dong

    2013-10-01

    With the yields of ferulic acid, coniferylferulate, Z-ligustilide, senkyunolide A, butylidenephthalide, butylphthalide, senkyunolide I, senkyunolide H, riligustilide, levistolide A, and total pharmacologically active ingredient as evaluation indexes, the extraction of Ligusticum chuanxiong by supercritical fluid technology was investigated through an orthogonal experiment L9 (3(4)). Four factors, namely temperature, pressure, flow rate of carbon dioxide, co-solvent concentration of the supercritical fluid, were investigated and optimized. Under the optimized conditions, namely 65 degrees C of temperature, 35 MPa of pressure, 1 L x min(-1) of CO2 flow rate, 8% of co-solvent concetration, supercritical fluid extraction could achieve a better yield than the conventional reflux extraction using methanol. And the supercritical fluid extraction process was validated to be stable and reliable.

  8. 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

  9. 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.

  10. 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

  11. Maximising opportunities in supercritical chemistry: the continuous conversion of levulinic acid to gamma-valerolactone in CO(2).

    PubMed

    Bourne, Richard A; Stevens, James G; Ke, Jie; Poliakoff, Martyn

    2007-11-28

    Phase behaviour is manipulated during the hydrogenation of aqueous levulinic acid in supercritical CO(2) to separate almost pure gamma-valerolactone from water and unreacted acid with reduced energy requirements compared to conventional processing.

  12. 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

  13. Methods for producing films using supercritical fluid

    DOEpatents

    Yonker, Clement R.; Fulton, John L.

    2004-06-15

    A method for forming a continuous film on a substrate surface that involves depositing particles onto a substrate surface and contacting the particle-deposited substrate surface with a supercritical fluid under conditions sufficient for forming a continuous film from the deposited particles. The particles may have a mean particle size of less 1 micron. The method may be performed by providing a pressure vessel that can contain a compressible fluid. A particle-deposited substrate is provided in the pressure vessel and the compressible fluid is maintained at a supercritical or sub-critical state sufficient for forming a film from the deposited particles. The T.sub.g of particles may be reduced by subjecting the particles to the methods detailed in the present disclosure.

  14. 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

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

    DOE PAGES

    Trevisan, Luca; Pini, Ronny; Cihan, Abdullah; ...

    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

  16. 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.

  17. Pore-scale supercritical CO2 dissolution and mass transfer under drainage conditions

    NASA Astrophysics Data System (ADS)

    Chang, Chun; Zhou, Quanlin; Oostrom, Mart; Kneafsey, Timothy J.; Mehta, Hardeep

    2017-02-01

    Recently, both core- and pore-scale imbibition experiments have shown non-equilibrium dissolution of supercritical CO2 (scCO2) and a prolonged depletion of residual scCO2. In this study, pore-scale scCO2 dissolution and mass transfer under drainage conditions were investigated using a two-dimensional heterogeneous micromodel and a novel fluorescent water dye with a sensitive pH range between 3.7 and 6.5. Drainage experiments were conducted at 9 MPa and 40 °C by injecting scCO2 into the sandstone-analogue pore network initially saturated by water without dissolved CO2 (dsCO2). During the experiments, time-lapse images of dye intensity, reflecting water pH, were obtained. These images show non-uniform pH in individual pores and pore clusters, with average pH levels gradually decreasing with time. Further analysis on selected pores and pore clusters shows that (1) rate-limited mass transfer prevails with slowly decreasing pH over time when the scCO2-water interface area is low with respect to the volume of water-filled pores and pore clusters, (2) fast scCO2 dissolution and phase equilibrium occurs when scCO2 bubbles invade into water-filled pores, significantly enhancing the area-to-volume ratio, and (3) a transition from rate-limited to diffusion-limited mass transfer occurs in a single pore when a medium area-to-volume ratio is prevalent. The analysis also shows that two fundamental processes - scCO2 dissolution at phase interfaces and diffusion of dsCO2 at the pore scale (10-100 μm) observed after scCO2 bubble invasion into water-filled pores without pore throat constraints - are relatively fast. The overall slow dissolution of scCO2 in the millimeter-scale micromodel can be attributed to the small area-to-volume ratios that represent pore-throat configurations and characteristics of phase interfaces. This finding is applicable for the behavior of dissolution at pore, core, and field scales when water-filled pores and pore clusters of varying size are surrounded

  18. 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.

  19. 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.

  20. New Class of Amphiphiles Designed for Use in Water-in-Supercritical CO2 Microemulsions.

    PubMed

    Sagisaka, Masanobu; Ogiwara, Shunsuke; Ono, Shinji; James, Craig; Yoshizawa, Atsushi; Mohamed, Azmi; Rogers, Sarah E; Heenan, Richard K; Yan, Ci; Peach, Jocelyn Alice; Eastoe, Julian

    2016-11-29

    Water-in-supercritical CO2 microemulsions formed using the hybrid F-H surfactant sodium 1-oxo-1-[4-(perfluorohexyl)phenyl]hexane-2-sulfonate, FC6-HC4, have recently been shown to have the highest water-solubilizing power ever reported. FC6-HC4 demonstrated the ability to outperform not only other surfactants but also other FCm-HCn analogues containing different fluorocarbon and hydrocarbon chain lengths (Sagisaka, M. et al. Langmuir 2015, 31, 7479-7487). With the aim of clarifying the key structural features of this surfactant, this study examined the phase behavior and water/supercritical CO2 aggregate formation of 1-oxo-1-[4-(perfluorohexyl)phenyl]hexane (Nohead FC6-HC4), which is an FC6-HC4 analogue but now, interestingly, without the sulfonate headgroup. Surprisingly, Nohead FC6-HC4, which would not normally be identified as a classic surfactant, yielded transparent single-phase W/CO2 microemulsions with polar cores able to solubilize a water-soluble dye, even at pressures and temperatures so low as to approach the critical point of CO2 (e.g., ∼100 bar at 35 °C). High-pressure small-angle scattering (SANS) measurements revealed the transparent phases to consist of ellipsoidal nanodroplets of water. The morphology of these droplets was shown to be dependent on the pressure, Nohead FC6-HC4 concentration, and water-to-surfactant molar ratio. Despite having almost the same structure as Nohead FC6-HC4, analogues containing both shorter and longer hydrocarbons were unable to form W/CO2 microemulsion droplets. This shows the importance of the role of the hydrocarbon chain in the stabilization of W/CO2 microemulsions. A detailed examination of the mechanism of Nohead FC6-HC4 adsorption onto the water surface suggests that the hexanoyl group protrudes into the aqueous core, allowing for association between the carbonyl group and water.

  1. 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

  2. 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.

    2013-06-30

    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.

  3. A laboratory study of supercritical CO2 adsorption on cap rocks in the geological storage conditions

    NASA Astrophysics Data System (ADS)

    Jedli, Hedi; Jbara, Abdessalem; Hedfi, Hachem; Bouzgarrou, Souhail; Slimi, Khalifa

    2017-04-01

    In the present study, various cap rocks have been experimentally reacted in water with supercritical CO2 in geological storage conditions ( P = 8 × 106 Pa and T = 80 °C) for 25 days. To characterize the potential CO2-water-rock interactions, an experimental setup has been built to provide additional information concerning the effects of structure, thermal and surface characteristics changes due to CO2 injection with cap rocks. In addition, CO2 adsorption capacities of different materials (i.e., clay evaporate and sandstone) are measured. These samples were characterized by XRD technique. The BET specific surface area was determined by nitrogen isotherms. In addition, thermal characteristics of untreated adsorbents were analyzed via TGA method and topography surfaces are identified by Scanning Electron Microscope (SEM). Taking into account pressure and temperature, the physical as well as chemical mechanisms of CO2 retention were determined. Isotherm change profiles of samples for relative pressure range indicate clearly that CO2 was adsorbed in different quantities. In accordance with the X-ray diffraction, a crystalline phase was formed due to the carbonic acid attack and precipitation of some carbonate.

  4. 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...

  5. 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

  6. Supercritical fluid thermodynamics for coal processing

    SciTech Connect

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

    1990-01-01

    Because of their unusual solvating and mass transfer properties, supercritical fluids show potential for a variety of coal processing applications. We have established a database of coal model compound equilibria; to add to this database, we have developed and are testing methods of rapidly measuring cosolvent effects on solubility. In addition, we have used fluorescence spectroscopy to study the nature of cosolvent effects on molecular level. The solubility and spectroscopic measurements are being used to guide the development of an equation of state that includes both physical and chemical interactions. The equation of state will be used to predict solubility behavior to systems can be designed for the processing of coal with supercritical fluids. 8 figs.

  7. Rapid analysis of polyolefin antioxidants and light stabilisers by supercritical fluid chromatography.

    PubMed

    Kithinji, J P; Bartle, K D; Raynor, M W; Clifford, A A

    1990-02-01

    Nineteen commercial antioxidants and light stabilisers, with a wide range of relative molecular masses and boiling-points, present in polyolefins were analysed by packed column supercritical fluid chromatography on four different phases with CO2 or 10% MeOH-CO2 as the mobile phase and with UV detection. The technique is shown to yield short analysis times and sufficient resolution for a number of additives present in a given polyolefin.

  8. 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

  9. 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.

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

    USGS Publications Warehouse

    Freifeild, Barry M.; Trautz, Robert C.; Kharaka, Yousif K.; Phelps, Tommy J.; Myer, Larry R.; Hovorka, Susan D.; Collins, Daniel 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 CO2sequestration 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.

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

    USGS Publications Warehouse

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

  12. Partitioning of Organic Compounds into Supercritical CO2 in Depleted Oil Reservoirs - A Review

    NASA Astrophysics Data System (ADS)

    Burant, A.; Lowry, G. V.; Karamalidis, A.

    2012-12-01

    Depleted oil reservoirs, with enhanced oil recovery, will be one of the first adopters of carbon capture and storage (CCS), which is a promising mitigation strategy for global climate change. The large scale implementation of CCS mandates better understanding of the risks associated with CO2 injection, especially in regards to potential leakage of the stored CO2. Organics, in the residual oil and dissolved in the brine, can partition into supercritical CO2 (sc-CO2) and move with that phase if it leaks. This review presents an overview of the thermodynamic models and trends in experimental partitioning data needed to understand what compounds may be expected to move with the sc-CO2. There are two main types of thermodynamic models used for predicting the solubility of organic compounds in sc-CO2, equations of state and quantitative structure activity relationships. Both can predict the partitioning behavior of one compound in sc-CO2, however only equations of state can predict solubility in multicomponent systems. In addition, equations of state have been developed to determine the effect of electrolytes on the partitioning behavior of organics dissolved in brines. There are three main trends in the partitioning behavior of organics in sc-CO2: Pure phase solubility follows trends in vapor pressure; compounds with higher volatility have higher solubility in sc-CO2. Second, the partitioning from water to sc-CO2 follows trends in Henry's constants, which follow the relative solubility of a compound in both the sc-CO2 and aqueous phases. Thirdly, the solubility of a compound can be enhanced by the presence of another; highly volatile compounds enhance the solubility of compounds with lower volatility. Finally, the review presents the gaps in experimental research that can be used to improve the modeling of the partitioning behavior of organics in sc-CO2, specifically in regards to co-solvency effects and the effects of electrolytes on the partitioning of dissolved

  13. A combined spectroscopic and theoretical study of dibutyltin diacetate and dilaurate in supercritical CO2.

    PubMed

    Renault, Benjamin; Cloutet, Eric; Cramail, Henri; Hannachi, Yacine; Tassaing, Thierry

    2008-09-11

    Two organotin catalysts, namely, dibutyltin dilaurate (DBTDL) and dibutyltin diacetate (DBTDA), commonly used in the synthesis of polyurethanes, have been investigated combining vibrational spectroscopic measurements with molecular modeling. The structure and vibrational spectra of the DBTDA molecule have been simulated using density functional theory. Thus, because of the Sn...O interactions, the lowest energy conformer reveals an asymmetrically chelated structure of the acetate groups with a C2v symmetry. The experimental IR spectra of DBTDA and DBTDL diluted in carbon tetrachloride and in supercritical CO2 show unambiguously that these molecules adopt the asymmetrically chelated conformation in the solvent. A new attribution of the main peaks constituting the respective IR spectra of the catalysts could be carried out. Finally, from the IR spectra of the two catalysts diluted in supercritical CO2 reported as a function of time, it was found that both molecules react slightly with CO2. However, their spectrum remains unchanged at the earliest stage of the polymerization, indicating that these molecules preserve a catalytic activity similar to that noted in conventional organic solvent.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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...

  19. Effects of Hexane in Supercritical Fluid Chromatography for the Separation of Enantiomers.

    PubMed

    Wu, Haihong; Yu, Stanley; Zeng, Lu

    2016-03-01

    Supercritical fluid chromatography (SFC), operated in conventional mode, is normally recognized as normal phase chromatography, and uses a solvent combination of supercritical CO2 and alcohols to separate compounds. Hexane, a commonly used solvent in normal phase liquid chromatography (NP-LC), is rarely used in SFC and, in some cases, is added to the organic modifiers to increase liquid content in order to achieve better efficiency in preparative SFC for poorly retained compounds. Although hexane is believed to have similar solvent strength to that of supercritical CO2, its effects on the enantioseparation in SFC is largely unknown. To understand the chromatographic effects of an apolar solvent, such as hexane in SFC, we compared the chromatographic behaviors of 35 chiral compounds using a parallel SFC method under traditional SFC mode of only “pure” alcohol-CO2 to that of hexane-assisted SFC (HA-SFC), which uses mixtures of alcohol and hexane (as cosolvents) and CO2. We observed that, in some cases, hexane behaves just like supercritical CO2, where replacement of a portion of CO2 with hexane does not significantly change retention times or resolution of the peaks. In many cases, however, addition of hexane in mobile phases does affect chromatographic behavior of one or both enantiomers. Such effects might provide opportunities for separation of some enantiomers.

  20. 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.

  1. 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

    2015-05-29

    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.

  2. 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

  3. 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.

  4. 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

  5. Using supercritical fluids to refine hydrocarbons

    SciTech Connect

    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.

  6. 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.

  7. 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.

  8. Ultrasound assisted supercritical fluid extraction of oil and coixenolide from adlay seed.

    PubMed

    Hu, Ai-jun; Zhao, Shuna; Liang, Hanhua; Qiu, Tai-qiu; Chen, Guohua

    2007-02-01

    Oil and coixenolide are important components of adlay seed (Coix lachrymal-jobi L. var. Adlay) with many beneficial functions to human health. In this work, a novel extraction technique--ultrasound assisted supercritical fluid extraction (USFE)--was studied. Effects of operating conditions on the extraction, including extraction temperature (T), pressure (P), time (t), CO(2) flow rate (F) and ultrasonic power (I) were investigated. There are optimum temperatures which gives the maximum extraction yields (EYs) for the supercritical fluid extractions with and without ultrasound. The effect of pressure on EYs for is similar to that of pressure on CO(2) density. Based on the yield of extraction, the favorable conditions for supercritical fluid extraction (SFE) were: T at 45 degrees C, P at 25 MPa, t at 4.0 h and F at 3.5L/h. While ultrasound was applied as in USFE, the following parameters were preferred: T at 40 degrees C, P at 20 MPa, t at 3.5h and F at 3.0 L/h, respectively. The results show that supercritical fluid extraction with the assistance of ultrasound could reduce the temperature, pressure, CO(2) flow rate, as well as time used in the process. Compared with SFE, USFE could give a 14% increase in the yield for extracting oil and coixenolide from adlay seed with less severe operating conditions.

  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. 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).

  11. 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.

  12. 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.

  13. 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

  14. Mineralogical changes of a well cement in various H2S-CO2(-brine) fluids at high pressure and temperature.

    PubMed

    Jacquemet, Nicolas; Pironon, Jacques; Saint-Marc, Jérémie

    2008-01-01

    The reactivity of a crushed well cement in contact with (1) a brine with dissolved H2S-CO2; (2) a dry H2S-CO2 supercritical phase; (3) a two-phase fluid associating a brine with dissolved H2S-CO2 and a H2S-CO2 supercritical phase was investigated in batch experiments at 500 bar and 120, 200 degrees C. All of the experiments showed that following 15-60 days cement carbonation occurred. The H2S reactivity with cement is limited since it only transformed the ferrites (minor phases) by sulfidation. It appeared that the primary parameter controlling the degree of carbonation (i.e., the rate of calcium carbonates precipitation and CSH (Calcium Silicate Hydrates) decalcification) is the physical state of the fluid phase contacting the minerals. The carbonation degree is complete when the minerals contact at least the dry H2S-CO2 supercritical phase and partial when they contactthe brine with dissolved H2S-CO2. Aragonite (calcium carbonate polymorph) precipitated specifically within the dry H2S-CO2 supercritical phase. CSH cristallinity is improved by partial carbonation while CSH are amorphized by complete carbonation. However, the features evidenced in this study cannot be directly related to effective features of cement as a monolith. Further studies involving cement as a monolith are necessary to ascertain textural, petrophysical, and mechanical evolution of cement.

  15. 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

  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.

  17. 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.

  18. Supercritical fluid thermodynamics from equations of state

    NASA Astrophysics Data System (ADS)

    Giovangigli, Vincent; Matuszewski, Lionel

    2012-03-01

    Supercritical multicomponent fluid thermodynamics are often built from equations of state. We investigate mathematically such a construction of a Gibbsian thermodynamics compatible at low density with that of ideal gas mixtures starting from a pressure law. We further study the structure of chemical production rates obtained from nonequilibrium statistical thermodynamics. As a typical application, we consider the Soave-Redlich-Kwong cubic equation of state and investigate mathematically the corresponding thermodynamics. This thermodynamics is then used to study the stability of H2-O2-N2 mixtures at high pressure and low temperature as well as to illustrate the role of nonidealities in a transcritical H2-O2-N2 flame.

  19. Supercritical fluid extraction: Recent advances and applications.

    PubMed

    Herrero, Miguel; Mendiola, Jose A; Cifuentes, Alejandro; Ibáñez, Elena

    2010-04-16

    Among the different extraction techniques used at analytical and preparative scale, supercritical fluid extraction (SFE) is one of the most used. This review covers the most recent developments of SFE in different fields, such as food science, natural products, by-product recovery, pharmaceutical and environmental sciences, during the period 2007-2009. The revision is focused on the most recent advances and applications in the different areas; among them, it is remarkable the strong impact of SFE to extract high value compounds from food and natural products but also its increasing importance in areas such as heavy metals recovery, enantiomeric resolution or drug delivery systems.

  20. 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.

  1. Preparation and anti-tumor evaluation of polyactin A microparticles from supercritical CO 2 processing

    NASA Astrophysics Data System (ADS)

    Bi, Jianhong; Zhao, Jinglan; Bao, Lang; Liu, Yan; Wu, Caosong

    2008-11-01

    This paper reports the use of a coating process based on supercritical fluid technology to prepare a solvent-free microparticles, loaded with a polymannopeptide (polyactin A, PAA) for enhancing optimal host response in cancer immunotherapy. Microparticles were characterized as regards their morphology, drug content and in vitro release. A prolonged release of the PAA had been achieved over a 24 h period from microparticles coated with the lipidic compound, which produced a more homogeneous, film-forming coating. Furthermore, it was shown that PAA did not undergo any degradation under the supercritical conditions used in the coating process. In vitro immunoactivity and anti-tumor effect analysis results showed that the PAA microparticle could efficiently trigger the induction of cytotoxic T lymphocytes (CTLs) in a sustained manner.

  2. 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

  3. 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.

  4. 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.

  5. Supercritical carbon dioxide (SC-CO2) extraction of essential oil from Swietenia mahagoni seeds

    NASA Astrophysics Data System (ADS)

    Norodin, N. S. M.; Salleh, L. M.; Hartati; Mustafa, N. M.

    2016-11-01

    Swietenia mahagoni (Mahogany) is a traditional plant that is rich with bioactive compounds. In this study, process parameters such as particle size, extraction time, solvent flowrate, temperature and pressure were studied on the extraction of essential oil from Swietenia mahagoni seeds by using supercritical carbon dioxide (SC-CO2) extraction. Swietenia mahagoni seeds was extracted at a pressure of 20-30 MPa and a temperature of 40-60°C. The effect of particle size on overall extraction of essential oil was done at 30 MPa and 50°C while the extraction time of essential oil at various temperatures and at a constant pressure of 30 MPa was studied. Meanwhile, the effect of flowrate CO2 was determined at the flowrate of 2, 3 and 4 ml/min. From the experimental data, the extraction time of 120 minutes, particle size of 0.5 mm, the flowrate of CO2 of 4 ml/min, at a pressure of 30 MPa and the temperature of 60°C were the best conditions to obtain the highest yield of essential oil.

  6. Supercritical fluid extraction of lycopene from tomato processing byproducts.

    PubMed

    Rozzi, N L; Singh, R K; Vierling, R A; Watkins, B A

    2002-04-24

    Tomato seeds and skins acquired from the byproduct of a local tomato processing facility were studied for supercritical fluid extraction (SFE) of phytochemicals. The extracts were analyzed for lycopene, beta-carotene, alpha-carotene, alpha-tocopherol, gamma-tocopherol, and delta-tocopherol content using high-performance liquid chromatography-electrochemical detection and compared to a chemically extracted control. SFEs were carried out using CO(2) at seven temperatures (32-86 degrees C) and six pressures (13.78-48.26 MPa). The effect of CO(2) flow rate and volume also was investigated. The results indicated that the percentage of lycopene extracted increased with elevated temperature and pressure until a maximum recovery of 38.8% was reached at 86 degrees C and 34.47 MPa, after which the amount of lycopene extracted decreased. Conditions for the optimum extraction of lycopene from 3 g of raw material were determined to be 86 degrees C, 34.47 MPa, and 500 mL of CO(2) at a flow rate of 2.5 mL/min. These conditions resulted in the extraction of 61.0% of the lycopene (7.19 microg lycopene/g).

  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 extraction of essential oil from aniseed (Pimpinella anisum L) using CO2: solubility, kinetics, and composition data.

    PubMed

    Rodrigues, Vera M; Rosa, Paulo T V; Marques, Marcia O M; Petenate, Ademir J; Meireles, M Angela A

    2003-03-12

    Supercritical fluid extraction (SFE) from aniseed using carbon dioxide was performed at 30 degrees C and pressures of 80-180 bar. The chemical composition of the SFE extract was determined by GC-MS; the quantitative analysis was done by GC-FID and TLC. The total amount of extractable substances or global yield (mass of extract/mass of feed) for the SFE process varied from 3.13 to 10.67% (mass). The solubilities of the anise essential oil in CO(2) were 0.0110, 0.0277, 0.0143, and 0.0182 kg of solute/kg of CO(2) at 80, 100, 140, and 180 bar, respectively. The major compounds identified and quantified in the extracts were anethole ( approximately 90%), gamma-himachalene (2-4%), p-anisaldehyde (<1%), methylchavicol (0.9-1.5%), cis-pseudoisoeugenyl 2-methylbutyrate ( approximately 3%), and trans-pseudoisoeugenyl 2-methylbutyrate ( approximately 1.3%). The Sovová model described quite well the experimental overall extraction curves.

  9. 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

  10. 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.

  11. 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

  12. Oxazoline-based antimicrobial oligomers: synthesis by CROP using supercritical CO2.

    PubMed

    Correia, Vanessa G; Bonifácio, Vasco D B; Raje, Vivek P; Casimiro, Teresa; Moutinho, Guilhermina; da Silva, Cláudia Lobato; Pinho, Mariana G; Aguiar-Ricardo, Ana

    2011-08-11

    A method using supercritical CO(2) to obtain biocompatible 2-oxazoline-based oligomers quaternized with different amines is described. The synthesized oligo(2-oxazoline)s display partial carbamic-acid insertion at one end. The syntheses of quaternary oligo(2-bisoxazoline)s and linear oligoethylenimine hydrochlorides are reported. Oligo(2-methyl-2-oxazoline) and oligo(2-bisoxazoline) quaternized with N,N-dimethyldodecylamine are the most efficient biocidal agents showing fast killing rates against Staphylococcus aureus and Escherichia coli. Linear oligoethylenimine hydrochloride shows the lowest MIC values but higher killing times against both bacteria. Based on the antimicrobial activity studies, a cooperative action of carbamic acid with the ammonium end group is proposed.

  13. [Optimization of extraction process for tannins from Geranium orientali-tibeticum by supercritical CO2 method].

    PubMed

    Xie, Song; Tong, Zhi-Ping; Tan, Rui; Liu, Xiao-Zhen

    2014-08-01

    In order to optimize extraction process conditions of tannins from Geranium orientali-tibeticum by supercritical CO2, the content of tannins was determined by phosphomolybdium tungsten acid-casein reaction, with extraction pressure, extraction temper- ature and extraction time as factors, the content of tannins from extract of G. orientali-tibeticum as index, technology conditions were optimized by orthogonal test. Optimum technology conditions were as follows: extraction pressure was 25 MPa, extraction temperature was 50 °C, extracted 1.5 h. The content of tannins in extract was 12.91 mg x g(-1), extract rate was 3.67%. The method established could be used for assay the contents of tannin in G. orientali-tibeticum. The circulated extraction was an effective extraction process that was stable and feasible, and that provides a way of the extraction process conditions of tannin from G. orientali-tibeticum.

  14. Comparative analysis of the oil and supercritical CO(2) extract of Cymbopogon citratus Stapf.

    PubMed

    Marongiu, Bruno; Piras, Alessandra; Porcedda, Silvia; Tuveri, Enrica

    2006-05-10

    Dried and ground leaves of lemon grass (Cymbopogon citratus Stapf.) were used as a matrix for supercritical extraction of essential oil with CO(2). The objective of this study was to analyze the influence of pressure on the supercritical extraction. A series of experiments were carried out, for 360 min, at 50 degrees C and at different pressures: 90, 100, 110 and 120 bar. Extraction conditions were chosen to maximize citral content in the extract oil. The collected extracts were analysed by GC-MS and their composition was compared with that of the essential oil isolated by hydrodistillation and by steam distillation. At higher solvent density the extract aspect changes passing from a characteristic yellow essential oil to yellowish semi-solid mass because of the extraction of high molecular mass compounds. The optimum conditions for citral extraction were 90 bar and 50 degrees C, at these conditions citral represent more than 68% of the essential oil and the extraction yield was 0.65% while the yield obtained from hydrodistillation was 0.43% with a content of citral of 73%.

  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. Welding immiscible polymers with a supercritical fluid.

    PubMed

    Wang, Xiaochu; Sanchez, Isaac C

    2007-11-20

    Polymer adhesion between two immiscible polymers is usually poor because there is little interpenetration of one polymer into the other at the interface. Increasing the width of the interfacial zone can enhance adhesion and mechanical properties. In principle, this can be accomplished by exposing heterogeneous polymer materials to a high-pressure fluid. The fluid can act as a common solvent and promote interpenetration. It also increases chain mobility at the interface, which helps to promote "welding" of the two polymers. A combination of the gradient theory of inhomogeneous systems and the Sanchez-Lacombe equation of state was used to investigate this phenomenon, especially the effect of the high compressibility of supercritical (SC) fluid on the compatibilization of two incompatible polymers. We calculate the interfacial density profile, interfacial thickness, and interfacial tension between the two polymers with and without the SC fluid. We find that the interfacial tension is decreased and the interfacial thickness is increased with high-pressure SC fluid for the ternary systems we have investigated. As the critical point is approached and the SC compressibility becomes large, no enhancement or deleterious effects on compatibilization were observed.

  17. In Situ Natural Abundance (17)O and (25)Mg NMR Investigation of Aqueous Mg(OH)2 Dissolution in the Presence of Supercritical CO2.

    PubMed

    Hu, Mary Y; Deng, Xuchu; Thanthiriwatte, K Sahan; Jackson, Virgil E; Wan, Chuan; Qafoku, Odeta; Dixon, David A; Felmy, Andrew R; Rosso, Kevin M; Hu, Jian Zhi

    2016-11-15

    We report an in situ high-pressure NMR capability that permits natural abundance (17)O and (25)Mg NMR characterization of dissolved species in aqueous solution and in the presence of supercritical CO2 fluid (scCO2). The dissolution of Mg(OH)2 (brucite) in a multiphase water/scCO2 fluid at 90 atm pressure and 50 °C was studied in situ, with relevance to geological carbon sequestration. (17)O NMR spectra allowed identification and distinction of various fluid species including dissolved CO2 in the H2O-rich phase, scCO2, aqueous H2O, and HCO3(-). The widely separated spectral peaks for various species can all be observed both dynamically and quantitatively at concentrations as low as 20 mM. Measurement of the concentrations of these individual species also allows an in situ estimate of the hydrogen ion concentration, or pCH(+) values, of the reacting solutions. The concentration of Mg(2+) can be observed by natural abundance (25)Mg NMR at a concentration as low as 10 mM. Quantum chemistry calculations of the NMR chemical shifts on cluster models aided in the interpretation of the experimental results. Evidence for the formation of polymeric Mg(2+) clusters at high concentrations in the H2O-rich phase, a possible critical step needed for magnesium carbonate formation, was found.

  18. 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.

  19. Preparation of monolithic matrices for oral drug delivery using a supercritical fluid assisted hot melt extrusion process.

    PubMed

    Lyons, John G; Hallinan, Mark; Kennedy, James E; Devine, Declan M; Geever, Luke M; Blackie, Paul; Higginbotham, Clement L

    2007-02-01

    The use of supercritical fluids as plasticisers in polymer processing has been well documented. The body of work described in this research paper outlines the use of a supercritical CO(2) assisted extrusion process in the preparation of a hot melt extruded monolithic polymer matrix for oral drug delivery. Several batches of matrix material were prepared with Carvedilol used as the active pharmaceutical ingredient (API). These batches were subsequently extruded both with and without supercritical CO(2) incorporation. The resultant matrices were characterised using steady-state parallel plate rheometry, differential scanning calorimetry (DSC), atomic force microscopy (AFM), micro-thermal analysis (microTA) and dissolution testing. Dissolution analysis showed that the use of supercritical CO(2) during the extrusion process resulted in a faster dissolution of API when compared with unassisted extrusion. The supercritical CO(2) incorporation also resulted in reduced viscosity during processing, therefore allowing for quicker throughput and productivity. The results detailed within this paper indicate that supercritical fluid assisted hot melt extrusion is a viable enhancement to conventional hot melt extrusion for the production of monolithic dosage forms.

  20. A biocompatible tissue scaffold produced by supercritical fluid processing for cartilage tissue engineering.

    PubMed

    Kim, Su Hee; Jung, Youngmee; Kim, Soo Hyun

    2013-03-01

    Supercritical fluids are used in various industrial fields, such as the food and medical industries, because they have beneficial physical and chemical properties and are also nonflammable and inexpensive. In particular, supercritical carbon dioxide (ScCO(2)) is attractive due to its mild critical temperature, pressure values, and nontoxicity. Poly(L-lactide-co-ɛ-caprolactone) (PLCL), which is a biocompatible, biodegradable, and very elastic polymer, has been used in cartilage tissue engineering. However, organic solvents, such as chloroform or dichloromethane, are usually used for the fabrication of a PLCL scaffold through conventional methods. This leads to a cytotoxic effect and long processing time for removing solvents. To alleviate these problems, supercritical fluid processing is introduced here. In this study, we fabricated a mechano-active PLCL scaffold by supercritical fluid processing for cartilage tissue engineering, and we compared it with a scaffold made by a conventional solvent-casting method in terms of physical and biological performance. Also, to examine the optimum condition for preparing scaffolds with ScCO(2), we investigated the effects of pressure, temperature, and the depressurization rate on PLCL foaming. The PLCL scaffolds produced by supercritical fluid processing had a homogeneously interconnected porous structure, and they exhibited a narrow pore size distribution. Also, there was no cytotoxicity of the scaffolds made with ScCO(2) compared to the scaffolds made by the solvent-pressing method. The scaffolds were seeded with chondrocytes, and they were subcutaneously implanted into nude mice for up to 4 weeks. In vivo accumulation of extracellular matrix of cell-scaffold constructs demonstrated that the PLCL scaffold made with ScCO(2) formed a mature and well-developed cartilaginous tissue compared to the PLCL scaffold formed by solvent pressing. Consequently, these results indicated that the PLCL scaffolds made by supercritical fluid

  1. Quantifying the flow dynamics of supercritical CO2-water displacement in a 2D porous micromodel using fluorescent microscopy and microscopic PIV

    NASA Astrophysics Data System (ADS)

    Kazemifar, Farzan; Blois, Gianluca; Kyritsis, Dimitrios C.; Christensen, Kenneth T.

    2016-09-01

    The multi-phase flow of liquid/supercritical CO2 and water (non-wetting and wetting phases, respectively) in a two-dimensional silicon micromodel was investigated at reservoir conditions (80 bar, 24 °C and 40 °C). The fluorescent microscopy and microscopic particle image velocimetry (micro-PIV) techniques were combined to quantify the flow dynamics associated with displacement of water by CO2 (drainage) in the porous matrix. To this end, water was seeded with fluorescent tracer particles, CO2 was tagged with a fluorescent dye and each phase was imaged independently using spectral separation in conjunction with microscopic imaging. This approach allowed simultaneous measurement of the spatially-resolved instantaneous velocity field in the water and quantification of the spatial configuration of the two fluid phases. The results, acquired with sufficient time resolution to follow the dynamic progression of both phases, provide a comprehensive picture of the flow physics during the migration of the CO2 front, the temporal evolution of individual menisci, and the growth of fingers within the porous microstructure. During that growth process, velocity jumps 20-25 times larger in magnitude than the bulk velocity were measured in the water phase and these bursts of water flow occurred both in-line with and against the bulk flow direction. These unsteady velocity events support the notion of pressure bursts and Haines jumps during pore drainage events as previously reported in the literature [1-3]. After passage of the CO2 front, shear-induced flow was detected in the trapped water ganglia in the form of circulation zones near the CO2-water interfaces as well as in the thin water films wetting the surfaces of the silicon micromodel. To our knowledge, the results presented herein represent the first quantitative spatially and temporally resolved velocity-field measurements at high pressure for water displacement by liquid/supercritical CO2 injection in a porous micromodel.

  2. Investigation of Transient, Turbulent Natural Convection in Vertical Tubes for Thermal Energy Storage in Supercritical CO2

    NASA Astrophysics Data System (ADS)

    Baghaei Lakeh, Reza; Lavine, Adrienne S.; Kavehpour, H. Pirouz; Wirz, Richard E.

    2013-11-01

    Heat transfer can be a limiting factor in the operation of thermal energy storage, including sensible heat and latent heat storage systems. Poor heat transfer between the energy storage medium and the container walls impairs the functionality of the thermal storage unit by requiring excessively long times to charge or discharge the system. In this study, the effect of turbulent, unsteady buoyancy-driven flow on heat transfer in vertical storage tubes containing supercritical CO2 as the storage medium is investigated computationally. The heat transfer from a constant-temperature wall to the storage fluid is studied during the charge cycle. The results of this study show that turbulent natural convection dominates the heat transfer mechanism and significantly reduces the required time for charging compared to pure conduction. Changing the L/D ratio of the storage tube has a major impact on the charge time. The charge time shows a decreasing trend with RaL. The non-dimensional model of the problem shows that Nusselt number and non-dimensional mean temperature of the storage fluid in different configurations of the tube is a function Buoyancy-Fourier number defined as of FoL * RaLm* L/D. This study was supported by award No. DE-AR0000140 granted by U.S. Department of Energy under Advanced Research Projects Agency - Energy (ARPA-E) and by award No. 5660021607 granted by Southern California Gas Company.

  3. Effect of combined treatment with supercritical CO2 and rosemary on microbiological and physicochemical properties of ground pork stored at 4°C.

    PubMed

    Huang, Shirong; Liu, Bin; Ge, Du; Dai, Jiehui

    2017-03-01

    The effect of combined treatment with supercritical CO2 (2000psi, 35°C for 2h) and rosemary powder (2.5% and 5.0% (w/w)) on microbiological and physicochemical properties of ground pork stored at 4°C was investigated. The changes in total viable count, pH, total volatile base nitrogen (TVB-N), lipid oxidation and instrumental color (CIE L(⁎), a(⁎), b(⁎)) were analyzed during a week period of refrigerated storage. It was found that microbial populations were reduced by supercritical CO2 treatment, with the more pronounced effect being achieved by combined treatment with supercritical CO2 and 5.0g rosemary powder/100g meat. Supercritical CO2 treatment for 2h could accelerate lipid oxidation of ground pork during refrigerated storage, whereas combination with rosemary can significantly slow down the increase of oxidation rate. Combined treatment of supercritical CO2 and rosemary significantly increased L(⁎) and b(⁎) values of the ground pork, while the a(⁎), pH and TVB-N value were not affected as compared to the treatment with supercritical CO2 alone. The results of this study indicate that combined treatment of supercritical CO2 and rosemary may be useful in the meat industry to enhance the storage stability of ground pork treated with long time exposure of supercritical CO2 during refrigerated storage.

  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.

  6. 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...

  7. A facile synthesis of poly(3-octylthiophene)-titanium dioxide nanocomposite particles in supercritical CO2.

    PubMed

    Yuvaraj, Haldorai; Woo, Min Hee; Park, Eun Ju; Gal, Yeong-Soon; Lim, Kwon Taek

    2008-09-01

    Poly(3-octylthiophene) (P3OT)-titanium dioxide (TiO2) nanocomposite powder where TiO2 was embedded with homogeneous dispersion was synthesized by in-situ chemical oxidative polymerization of 3-octylthiophene in the presence of TiO2 nanoparticles in supercritical carbon dioxide (scCO2), using ferric chloride as the oxidant. The synthesized materials could be obtained as dry powder upon venting of CO2 after the polymerization. The composites were subsequently characterized by FT-IR spectroscopy, transmission electron microscopy (TEM), X-ray diffraction studies (XRD), thermogravimetric analysis (TGA) and photoluminescence (PL). The incorporation of TiO2 in the composite was endorsed by FT-IR studies. TGA revealed enhanced thermal stability of P3OT/TiO2 nanocomposite compared to 3-octylthiophene. TEM analysis showed that well dispersed TiO2 nanoparticles in the polymer matrix. Photoluminescence quenching increased with increasing TiO2 concentration in the composite.

  8. Development and stability of semisolid preparations based on a supercritical CO2 Arnica extract.

    PubMed

    Bilia, Anna Rita; Bergonzi, Maria Camilla; Mazzi, Giovanni; Vincieri, Franco Francesco

    2006-05-03

    Conventional herbal drug preparations (HDP) based on Arnica montana L. have a low content of the active principles, sesquiterpene lactones, which show poor stability and low physical compatibility in semisolid formulations. Recently, an innovative supercritical carbon dioxide (CO2) extract with high sesquiterpene content has been marketed. Development of six semisolid preparations (cetomacrogol, polysorbate 60, polawax, anphyphil, natrosol and sepigel) based on this innovative CO2 extract is discussed. Stability of these preparations was investigated according to ICH guidelines. The evaluation of in vitro release of active constituents was performed using the cell method reported in the European Pharmacopoeia. Preliminary data on in vivo permeation of three selected formulations is demonstrated using the "skin stripping" test, according to the FDA, in healthy subjects. Analysis of sesquiterpene lactones within the extract and in vitro and in vivo studies was performed by RP-HPLC-DAD-MS method. The cetomacrogol showed the best release profile in the in vitro test, while in the in vivo test the best preparation resulted polysorbate 60 and polawax.

  9. 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

  10. Supercritical CO2 Power Cycles: Design Considerations for Concentrating Solar Power

    SciTech Connect

    Neises, Ty; Turchi, Craig

    2014-09-01

    A comparison of three supercritical CO2 Brayton cycles: the simple cycle, recompression cycle and partial-cooling cycle indicates the partial-cooling cycle is favored for use in concentrating solar power (CSP) systems. Although it displays slightly lower cycle efficiency versus the recompression cycle, the partial-cooling cycle is estimated to have lower total recuperator size, as well as a lower maximum s-CO2 temperature in the high-temperature recuperator. Both of these effects reduce recuperator cost. Furthermore, the partial-cooling cycle provides a larger temperature differential across the turbine, which translates into a smaller, more cost-effective thermal energy storage system. The temperature drop across the turbine (and by extension, across a thermal storage system) for the partial-cooling cycle is estimated to be 23% to 35% larger compared to the recompression cycle of equal recuperator conductance between 5 and 15 MW/K. This reduces the size and cost of the thermal storage system. Simulations by NREL and Abengoa Solar indicate the partial-cooling cycle results in a lower LCOE compared with the recompression cycle, despite the former's slightly lower cycle efficiency. Advantages of the recompression cycle include higher thermal efficiency and potential for a smaller precooler. The overall impact favors the use of a partial-cooling cycle for CSP compared to the more commonly analyzed recompression cycle.

  11. Liberation of microbial substrates from macromolecular organic matter by non-supercritical CO2

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    The worldwide search for suitable underground storage formations for CO2 also considers coal-bearing strata. CO2 is already injected into coal seams for enhanced recovery of coal bed methane. However, the geochemical and microbiological effects of increased CO2 concentrations 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. 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 under acidic conditions. Recent investigations outlined the importance of LMWOAs as a feedstock for subsurface microbial life [1]. Therefore, injection of CO2 into coal formations may result in enhanced nutrient supply for subsurface microbes. To investigate the effects of highly CO2-saturated waters on the release of LMWOAs from coal, we developed an inexpensive high-pressure-high-temperature system that allows manipulating the concentration of dissolved gases up to 60 MPa and 120°C, respectively. The sample is placed in a flexible, gas-tight and inert PVDF sleeve, separating it from the pressure fluid and allowing for subsampling without loss of pressure. Lignite samples from the DEBITS-1 well, Waikato Basin, NZ and the Welzow-Süd open-cast mine, Niederlausitz, Germany, were extracted at 90° C and 5 MPa, with either pure water, CO2-saturated water, CO2/NO2 or CO2/SO2-saturated water. Subsamples were taken at different time points during the 72 hrs. long extraction. Extraction of LMWOAs from coal samples with our pressurised system resulted in yields that were up to four times higher than those reported for Soxhlet extraction [2]. These higher yields may be explained by the fact that during Soxhlet extraction the sample only gets into contact with freshly distilled water, whereas in our system the extraction fluid is circulated, resulting in

  12. Phytochemical profile, antioxidant and antimicrobial activity of extracts obtained from erva-mate (Ilex paraguariensis) fruit using compressed propane and supercritical CO2.

    PubMed

    Fernandes, Ciro E F; Scapinello, Jaqueline; Bohn, Aline; Boligon, Aline A; Athayde, Margareth L; Magro, Jacir Dall; Palliga, Marshall; Oliveira, J Vladimir; Tres, Marcus V

    2017-01-01

    Traditionally, Ilex paraguariensis leaves are consumed in tea form or as typical drinks like mate and terere, while the fruits are discarded processing and has no commercial value. The aim of this work to evaluate phytochemical properties, total phenolic compounds, antioxidant and antimicrobial activity of extracts of Ilex paraguariensis fruits obtained from supercritical CO2 and compressed propane extraction. The extraction with compressed propane yielded 2.72 wt%, whereas with supercritical CO2 1.51 wt% was obtained. The compound extracted in larger amount by the two extraction solvents was caffeine, 163.28 and 54.17 mg/g by supercritical CO2 and pressurized propane, respectively. The antioxidant activity was more pronounced for the supercritical CO2 extract, with no difference found in terms of minimum inhibitory concentration for Staphylococcus aureus for the two extracts and better results observed for Escherichia coli when using supercritical CO2.

  13. Fluid chemistry of the onshore CO2 sequestration formation at Nagaoka, Japan: 5 years passed since CO2 injection

    NASA Astrophysics Data System (ADS)

    Mito, S.; Asahara, Y.; Xue, Z.

    2011-12-01

    The CO2 injection into structural reservoirs in deep permeable geologic formations is now expected one of the most realizable methods from the point of view of the cost and the CO2 preserving capability of the geological reservoirs. The first Japanese pilot-scale CO2 sequestration project has been done in an onshore saline aquifer at Nagaoka-site, Japan. 10,400 tones of CO2 were injected into a thin aquifer at the depth of 1110 m at a rate of 20-40 tones from July 2003 to January 2005. To investigate a chemical reaction between CO2 fluids and rock forming minerals at the sequestration formation, formation water was collected before and after 1year of the injection (Mito et al., 2008). The result of chemical analyses exhibited a high concentration of HCO3-, Ca, Mg, Fe, Mn and Si in the post-CO2 injection samples compared to the original formation water. The result indicated that a chemical reaction between CO2 and formation water and rock forming minerals had occurred in the sequestration formation at the early stage of CO2 storage. A continuous resistivity monitoring from 2003 to 2011 showed an existence of stagnant free CO2 at the depth of 1110m and gradual spreading of CO2 dissolved water at a top and a bottom of the free CO2 layer (Mito and Xue 2011). This observation suggests that the CO2 trapped by formation water have gradually diffused and chemical trapping of CO2 by surrounding minerals have progressed in the formation. For long-term CO2 storage, we should clarify the reaction between CO2 and minerals occurred at the edge of the spreading CO2 fluids. We are going to collect formation water in the sequestration site at November 2011. We will show the analytical result of the sampled water and discuss about the long-term chemical reaction between the diffused CO2 fluids and rock forming minerals at the Nagaoka sequestration site. References Mito et al., 2008. International Journal of Greenhouse Gas Control, 2, 309-318. Mito and Xue 2011. Energy procedia, 4

  14. 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.

  15. Fatty and resin acid analysis in tall oil products via supercritical fluid extraction-supercritical fluid reaction using enzymatic catalysis.

    PubMed

    Taylor, S L; King, J W

    2001-07-01

    Supercritical fluid extraction (SFE) is combined with supercritical fluid reaction (SFR) in an analytical mode to assess tall oil products for their fatty or resin acid content or both. The SFR consists of an inline enzymatically catalyzed reaction in which a lipase transesterifies specific lipids with methanol. The SFE-SFR sequence is conducted employing commercially available extractors using supported lipases in the extraction cell to form methyl esters. In this study, six different commercially available lipases are screened for activity. The SFE-SFR extracts are analyzed by capillary gas chromatography and supercritical fluid chromatography and then compared with tall oil products derivatized by conventional chemical derivatization techniques.

  16. 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.

  17. 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.

  18. 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, ...

  19. 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

  20. 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

  1. Photoreduction of CO2 using [Ru(bpy)2(CO)L]n+ catalysts in biphasic solution/supercritical CO2 systems.

    PubMed

    Voyame, Patrick; Toghill, Kathryn E; Méndez, Manuel A; Girault, Hubert H

    2013-10-07

    The reduction of CO2 in a biphasic liquid-condensed gas system was investigated as a function of the CO2 pressure. Using 1-benzyl-1,4-dihydronicotinamide (BNAH) as sacrificial electron donor dissolved in a dimethylformamide-water mixture and [Ru(bpy)2(CO)L](n+) as a catalyst and [Ru(bpy)3](2+) as a photosensitizer, the reaction was found to produce a mixture of CO and formate, in total about 250 μmol after just 2 h. As CO2 pressure increases, CO formation is greatly favored, being four times greater than that of formate in aqueous systems. In contrast, formate production was independent of CO2 pressure, present at about 50 μmol. Using TEOA as a solvent instead of water created a single-phase supercritical system and greatly favored formate synthesis, but similarly increasing CO2 concentration favored the CO catalytic cycle. Under optimum conditions, a turnover number (TON) of 125 was obtained. Further investigations of the component limits led to an unprecedented TON of over 1000, and an initial turnover frequency (TOF) of 1600 h(-1).

  2. 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.

  3. 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.

  4. Comparative analysis of the oil and supercritical CO2 extract of Elettaria cardamomum (L.) Maton.

    PubMed

    Marongiu, Bruno; Piras, Alessandra; Porcedda, Silvia

    2004-10-06

    The volatile oil of Elettaria cardamomum (L.) Maton seeds was obtained by supercritical CO(2) extraction (SC-CO(2)). The effect of the extraction conditions on the yield and composition of the resulting cardamom volatile oil was examined by testing two pressure values, 9.0 and 11.0 MPa; two temperatures, 40 and 50 degrees C; two flow rate values, 0.6 and 1.2 kg/h; and two particles size values, 250-425 and >850 microm. The extraction conditions that gave the highest yield, Y (grams of extract per gram of seeds), of 5.5%, were as follows: pressure, 9.0 MPa; temperature, 40 degrees C; carbon dioxide flow, phi = 1.2 kg/h; and particles sizes in the range of 250-425 microm. Waxes, recovered as traces, were entrapped in the first separator set at 9.0 MPa and -10 degrees C. The oil was recovered in the second separator working at 1.5 MPa and 10 degrees C. The main components were as follows: alpha-terpinyl acetate, 42.3%; 1,8-cineole, 21.4%; linalyl acetate, 8.2%; limonene, 5.6%; and linalool, 5.4%. A comparison with the hydrodistilled oil, obtained at a yield of 5.0%, did not reveal any consistent difference. In contrast, the extract obtained using hexane, Y = 7.6%, showed strong composition differences. Indeed, the volatile fraction of the extract was made up mainly of the following: limonene, 36.4%; 1,8-cineole, 23.5%; terpinolene, 8.6%; and myrcene, 6.6%.

  5. 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

    2014-10-08

    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.

  6. Laboratory Seismic Monitoring and X-ray CT imaging of Supercritical CO2 Injection in Reservoir Sand: WESTCAB King Island Project

    NASA Astrophysics Data System (ADS)

    Nakashima, S.; Kneafsey, T. J.; Nakagawa, S.; Harper, E. J.

    2013-12-01

    The Central Valley of California contains promising locations for on-shore geologic CO2 storage. DOE's WESTCARB (West Coast Regional Carbon Sequestration Partnership) project drilled and cored a borehole (Citizen Green Well) at King Island (near Stockton, CA) to study the CO2 storage capability of saline and gas-bearing formations in the southwestern Sacramento Basin. Potential reservoirs encountered in the borehole include Domengine, Mokelumne River (primary target), and Top Starkey formations. In anticipation of geophysical monitoring of possible CO2 injection into this particular borehole and of the long-term migration of the CO2, we conducted small-scale CO2 injection experiments on three core samples retrieved from the well (Mokelumne River sand A and B) and from a mine outcrop (Domengine sandstone). During the experiment, a jacketed core sample (diameter 1.5 inches, length 4.0-6.0 inches) saturated with brine- (1% NaCl aq.) was confined within a pressure vessel via compressed nitrogen to 3,500-4,000psi, and supercritical CO2 was injected into the core at 2,000-2,500psi and 45-60 degrees C. The CO2 pressure and temperature were adjusted so that the bulk elastic modulus of the CO2 was close to the expected in-situ modulus--which affects the seismic properties most--while keeping the confining stress within our experimental capabilities. After the CO2 broke through the core, fresh brine was re-injected to remove the CO2 by both displacement and dissolution. Throughout the experiment, seismic velocity and attenuation of the core sample were measured using the Split Hopkinson Resonant Bar method (Nakagawa, 2012, Rev. Sci. Instr.) at near 1 kHz (500Hz--1.5 kHz), and the CO2 distribution determined via x-ray CT imaging. In contrast to relatively isotropic Mokelumne sand A, Domengine sandstone and Mokelumne sand B cores exhibited CO2 distributions strongly controlled by the bedding planes. During the CO2 injection, P-wave velocity and attenuation of the layered

  7. 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

  8. Surface modification of chitin using ultrasound-assisted and supercritical CO2 technologies for cobalt adsorption.

    PubMed

    Dotto, Guilherme L; Cunha, Jeanine M; Calgaro, Camila O; Tanabe, Eduardo H; Bertuol, Daniel A

    2015-09-15

    Ultrasound-assisted (UA) and supercritical CO2 technologies (SCO2) were used to modify the chitin surface and, improve its adsorption characteristics regarding to cobalt. Chitin, before and after the treatments, was characterized by N2 adsorption isotherms (BET), infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Unmodified and surface modified chitins were used as adsorbents to remove cobalt from aqueous solutions. The adsorption study was performed by equilibrium isotherms and kinetic curves. The chitin particle characteristics, such as, surface area, pore volume and porosity were improved by the UA and SCO2 treatments. The crystallinity index decreased after the UA and SCO2 treatments, and also, intense surface modifications were observed. Langmuir and Freundlich models were adequate to represent the adsorption equilibrium. The maximum adsorption capacities were 50.03, 83.94 and 63.08 mg g(-1) for unmodified chitin, UA surface modified chitin and SCO2 surface modified chitin. The adsorption kinetic curves were well represented by the pseudo-second order model. UA and SCO2 technologies are alternatives to modify the chitin surface and improve its adsorption characteristics.

  9. 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.

  10. Atomic Layer Deposition of High-k Dielectrics Using Supercritical CO2

    NASA Astrophysics Data System (ADS)

    Shende, Rajesh

    2005-03-01

    Atomic layer deposition (ALD) of high-κdielectric was performed in supercritical CO2 (SCCO2), using a two-step reaction sequence. In step one, tetraethoxy silane (TEOS) precursor was injected in SCCO2 at 80-100 C and 50 MPa pressure to obtain a chemisorbed surface monolayer, which was then oxidized into SiO2 using peroxide entrained in SCCO2. ALD process was controlled by estimating precursor solubility and its mass transport with respect to the density of SCCO2, and correlating these parameters with precursor injection volume. In the ALD process, 7 pulses of precursor were used anticipating deposition of one atomic layer in each of the pulses. The thickness of the SiO2 atomic layers deposited using SCCO2 was measured by variable angle spectroscopic ellipsometry (VASE), and the C-V measurements were also performed. The result obtained using VASE indicates that there were 7 monolayers of SiO2 with total thickness of 35 å, and the dielectric constant of the deposited layers was 4.0±0.1. Our initial findings clearly demonstrate that SCCO2 is capable of atomic layer deposition of high quality dielectric films at very low process temperatures preventing interface reaction. More research is in progress to achieve ALD of HfO2 and TiO2 in SCCO2.

  11. 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...

  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. 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.

  14. 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.

  15. 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.

  16. Supercritical fluid precipitation of recombinant human immunoglobulin from aqueous solutions.

    PubMed

    Nesta, D P; Elliott, J S; Warr, J P

    2000-02-20

    Supercritical carbon dioxide was used as an antisolvent for producing recombinant human immunoglobulin G (rIgG) particulate powders. Liquid carbon dioxide (CO(2)) was premixed with ethanol to create a single-phase, modified supercritical fluid (SCF). The modified SCF was then vigorously mixed with a pharmaceutically acceptable, aqueous formulation of rIgG, and the mixture was immediately atomized into a pressurized vessel where rapid expansion of the modified SCF extracted the aqueous phase, resulting in precipitation of the protein powder. The process was reproducible, and resulting powder products were characterized by their aqueous solubilities, and the spectroscopic profile, molecular integrity, and antigen binding activity of the individual soluble fractions. Molecular integrity was assessed via size-exclusion high-performance liquid chromatography (SEC), whereas antigen binding activity was determined using an enzyme-linked immunosorbent assay (ELISA). Attempts to characterize particle size and morphology were confounded due to the extremely deliquescent nature of the powders, causing them to absorb moisture rapidly and become gummy. Operational conditions were optimized to a point which yielded powders that were completely soluble, and had ultraviolet (UV) spectroscopic and SEC profiles indistinguishable from those of the reference standard starting solution from which the powders were derived. Antigen binding activities of the powders, however, were

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

    DOE PAGES

    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

  18. 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

    2012-04-03

    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.

  19. 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

  20. 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

  1. 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

  2. Isolation of essential oil from different plants and herbs by supercritical fluid extraction.

    PubMed

    Fornari, Tiziana; Vicente, Gonzalo; Vázquez, Erika; García-Risco, Mónica R; Reglero, Guillermo

    2012-08-10

    Supercritical fluid extraction (SFE) is an innovative, clean and environmental friendly technology with particular interest for the extraction of essential oil from plants and herbs. Supercritical CO(2) is selective, there is no associated waste treatment of a toxic solvent, and extraction times are moderate. Further, supercritical extracts were often recognized of superior quality when compared with those produced by hydro-distillation or liquid-solid extraction. This review provides a comprehensive and updated discussion of the developments and applications of SFE in the isolation of essential oils from plant matrices. SFE is normally performed with pure CO(2) or using a cosolvent; fractionation of the extract is commonly accomplished in order to isolate the volatile oil compounds from other co-extracted substances. In this review the effect of pressure, temperature and cosolvent on the extraction and fractionation procedure is discussed. Additionally, a comparison of the extraction yield and composition of the essential oil of several plants and herbs from Lamiaceae family, namely oregano, sage, thyme, rosemary, basil, marjoram and marigold, which were produced in our supercritical pilot-plant device, is presented and discussed.

  3. Evaluation and Countermeasures of Convective Heat Transfer on Thermal Conductivity Measurement Using the Peltier Effect and Application to Supercritical CO2

    NASA Astrophysics Data System (ADS)

    Chen, Zai-hua; Tozaki, Ken-ichi; Nishikawa, Keiko

    1999-12-01

    In the previous paper, the present authors reported a newlydeveloped method of thermal conductivity measurement for fluids usinga thermoelectric module. It was very simple and effective for samplesin supercritical states. However, the countermeasures against thermalperturbation were insufficient. In the present work, some improvementshave been made on the apparatus to eliminate thermal convection. Theconvective heat transfer effect on the measurement has been evaluatedby varying the temperature difference across the sample layer. It hasbeen found that the convection-free conductivity for critical andsupercritical fluids can be determined by extrapolation of thetemperature difference to 0. The thermal conductivity ofsupercritical CO2 measured by the improved method is presented,including the states near the critical point.

  4. Ionic Effects on Supercritical CO2-Brine Interfacial Tensions: Molecular Dynamics Simulations and a Universal Correlation with Ionic Strength, Temperature, and Pressure.

    PubMed

    Zhao, Lingling; Ji, Jiayuan; Tao, Lu; Lin, Shangchao

    2016-09-13

    For geological CO2 storage in deep saline aquifers, the interfacial tension (IFT) between supercritical CO2 and brine is critical for the storage security and design of the storage capacitance. However, currently, no predictive model exists to determine the IFT of supercritical CO2 against complex electrolyte solutions involving various mixed salt species at different concentrations and compositions. In this paper, we use molecular dynamics (MD) simulations to investigate the effect of salt ions on the incremental IFT at the supercritical CO2-brine interface with respect to that at the reference supercritical CO2-water interface. Supercritical CO2-NaCl solution, CO2-CaCl2 solution and CO2-(NaCl+CaCl2) mixed solution systems are simulated at 343 K and 20 MPa under different salinities and salt compositions. We find that the valence of the cations is the primary contributor to the variation in IFT, while the Lennard-Jones potentials for the cations pose a smaller impact on the IFT. Interestingly, the incremental IFT exhibits a general linear correlation with the ionic strength in the above three electrolyte systems, and the slopes are almost identical and independent of the solution types. Based on this finding, a universal predictive formula for IFTs of CO2-complex electrolyte solution systems is established, as a function of ionic strength, temperature, and pressure. The predicted IFTs using the established formula agree perfectly (with a high statistical confidence level of ∼96%) with a wide range of experimental data for CO2 interfacing with different electrolyte solutions, such as those involving MgCl2 and Na2SO4. This work provides an efficient and accurate route to directly predict IFTs in supercritical CO2-complex electrolyte solution systems for practical engineering applications, such as geological CO2 sequestration in deep saline aquifers and other interfacial systems involving complex electrolyte solutions.

  5. 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

  6. On the interaction between supercritical CO2 and epoxides combining infrared absorption spectroscopy and quantum chemistry calculations.

    PubMed

    Foltran, Stéphanie; Méreau, Raphaël; Tassaing, Thierry

    2011-05-28

    The nature and strength of the interactions occurring between epoxides and CO(2) have been investigated by combining infrared spectroscopy with quantum chemistry calculations. A series of infrared absorption experiments on four model epoxide molecules highly diluted in supercritical CO(2) have been performed at constant temperature T = 40 °C for various CO(2) pressures varying from 1 to 30 MPa. Then, we carried out a theoretical analysis based on quantum chemistry calculations using Density Functional Theory (B3PW91 and CAM-B3LYP) and ab initio (MP2) computational methods. A very good agreement between experimental and calculated vibrational frequency shifts of the epoxide ring vibrations group was obtained using the CAM-B3LYP functional, hence validating the calculated optimized geometries of the epoxide-CO(2) complexes. Whatever the epoxide considered, CO(2) is found to be on average above the oxygen atom of the epoxy ring and interacts with the carbon atom of CO(2) through a Lewis acid-Lewis base type of interaction. The substituents on the epoxide ring are found to influence the stability of the epoxide-CO(2) complexes mainly because of the partial charge on the oxygen atom that is sensitive to the nature of the substituent.

  7. 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%).

  8. 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.

  9. 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.

  10. 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.

  11. CO2-rich fluid inclusions in greenschists, migmatites, granulites, and hydrated granulites

    NASA Technical Reports Server (NTRS)

    Hollister, L. S.

    1988-01-01

    Data was discussed from several different terrains in which CO2-rich fluid inclusions occur despite parageneses that predict the presence of H2O-rich fluids. CO2-rich fluid inclusions, some having densities appropriate for peak-metamorphic conditions, were found in greenschists, amphibolites, migmatites, and hydrated granulites. The author suggested that there may be a common process that leads to CO2-rich secondary inclusions in metamorphic rocks.

  12. 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.

  13. 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.

  14. 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.

  15. [Technology of extraction of essential oil from leaves of Vitex negundo L. var. heterophylla (Franch.) Rehd. by supercritical CO2 apparatus].

    PubMed

    Xie, Jianchun; Sun, Baoguo; Zheng, Fuping; Yu, Min

    2005-12-01

    By the designation of mono-factor experiments and orthogonal multifactor experiments, influences of extraction temperature, extraction pressure, CO2 flow rate and extraction times on the yield of oil from the leaves of Vitex negundo L. var. heterophylla (Franch.) Rehd. in the supercritical CO2 extraction process were investigated. The obtained optimal extraction technology was: the extraction pressure: 22 MPa; the extraction temperature: 45 degrees C; the CO2 flow rate: 25 L/h and the extraction time: 3h. The oil yield on the above supercritical CO2 extraction conditions was 3.22%.

  16. Gibbs ensemble Monte Carlo simulation of supercritical CO2 adsorption on NaA and NaX zeolites

    NASA Astrophysics Data System (ADS)

    Liu, Shanshan; Yang, Xiaoning

    2006-06-01

    Adsorption of supercritical carbon dioxide on two kinds of zeolites with identical chemical composition but different pore structure (NaA and NaX) was studied using the Gibbs ensemble Monte Carlo simulation. The model frameworks for the two zeolites with Si /Al ratio being unity have been chosen as the solid structures in the simulation. The adsorption behaviors of supercritical CO2 on the NaA and NaX zeolites, based on the adsorption isotherms and isosteric heats of adsorption, were discussed in detail and were compared with the available experimental results. A good agreement between the simulated and experimental results is obtained for both the adsorbed amount and the bulk phase density. The intermediate configurational snapshots and the radial distribution functions between zeolite and adsorbed CO2 molecules were collected in order to investigate the preferable adsorption locations and the confined structure behavior of CO2. The structure behaviors of the adsorbed CO2 molecules show various performances, as compared with the bulk phase, due to the confined effect in the zeolite pores.

  17. 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.

  18. 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

  19. 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.

  20. Geological controls on supercritical fluid resources in volcanic geothermal systems

    NASA Astrophysics Data System (ADS)

    Scott, S. W.; Driesner, T.; Weis, P.

    2014-12-01

    Large-scale fluid convection in conventional volcanic geothermal systems is driven by the hydrothermal cooling of shallow intrusions. Recently, there has been increased interest in tapping supercritical fluid resources in volcanic geothermal systems, since such fluid reservoirs could provide a roughly order-of-magnitude greater potential for electricity production than conventional geothermal wells drilled to temperatures of 250-300 °C. The potential of supercritical geothermal reservoirs was demonstrated in 2010, when the Iceland Deep Drilling Project (IDDP) drilled into liquid magma at 2 km depth and encountered an overlying permeable, high-temperature (~450 °C) fluid reservoir capable of more than ~30 MWe of electricity production. However, a conceptual model describing the main factors governing the extent and structure of target reservoirs has remained elusive. Here, we present the first systematic investigation of the role of rock permeability, the brittle-ductile transition temperature, and the depth of magma chamber emplacement on the development of supercritical fluid reservoirs. We use the numerical modeling code CSMP++ to model two-phase flow of compressible water around an initially elliptical, 900 °C intrusion. Our models indicate that potentially exploitable supercritical fluid resources are an integral part of many magma-driven geothermal systems. Hotter and more extensive reservoirs are promoted by a brittle-ductile transition temperature higher than ~400 °C, an intrusion depth less than 3 km, and a host rock permeability of 10-14 to 10-15 m2. The systematic dependence of the size, location and hydrologic behavior of supercritical reservoirs on these factors aids the development of exploration models for different volcanic settings. In addition, by serving as the main agents of heat transfer at the interface of an intrusion and the overlying hydrothermal system, supercritical fluid reservoirs play a decisive role in determining the overall

  1. Research and development opportunities in supercritical fluid technology: Final report

    SciTech Connect

    Not Available

    1989-08-01

    On December 2, 1988, the US Department of Energy (DOE) held a workshop on supercritical fluid technology. The purpose of this workshop was to elicit research ideas from participants representing government, industry, and academia. A special concern was to determine the appropriate level of involvement for DOE and other organizations in order to develop commercial supercritical fluid technology. Group presentations and a general discussion were held to summarize the results. Comments on the general roles of DOE and industry in supercritical fluid R D included: some industries (e.g., food processing) are already researching this technology; DOE should cooperate with industry in attempting to demonstrate this technology; and direct support of private-sector projects by DOE should be encouraged. It was also noted that productivity benefits may outweigh energy conservation benefits in some application areas. 1 fig., 5 tabs.

  2. 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

  3. 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.

  4. 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.

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

    SciTech Connect

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

    2014-01-07

    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.

  6. 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)

  7. Effect of supercritical fluid density on nanoencapsulated drug particle size using the supercritical antisolvent method.

    PubMed

    Kalani, Mahshid; Yunus, Robiah

    2012-01-01

    The reported work demonstrates and discusses the effect of supercritical fluid density (pressure and temperature of supercritical fluid carbon dioxide) on particle size and distribution using the supercritical antisolvent (SAS) method in the purpose of drug encapsulation. In this study, paracetamol was encapsulated inside L-polylactic acid, a semicrystalline polymer, with different process parameters, including pressure and temperature, using the SAS process. The morphology and particle size of the prepared nanoparticles were determined by scanning electron microscopy and transmission electron microscopy. The results revealed that increasing temperature enhanced mean particle size due to the plasticizing effect. Furthermore, increasing pressure enhanced molecular interaction and solubility; thus, particle size was reduced. Transmission electron microscopy images defined the internal structure of nanoparticles. Thermal characteristics of nanoparticles were also investigated via differential scanning calorimetry. Furthermore, X-ray diffraction pattern revealed the changes in crystallinity structure during the SAS process. In vitro drug release analysis determined the sustained release of paracetamol in over 4 weeks.

  8. 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.

  9. 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.

  10. 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.

  11. [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.

  12. 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.

  13. Monitoring of technical oils in supercritical CO(2) under continuous flow conditions by NIR spectroscopy and multivariate calibration.

    PubMed

    Bürck, J; Wiegand, G; Roth, S; Mathieu, H; Krämer, K

    2006-02-28

    Metal parts and residues from machining processes are usually polluted with cutting or grinding oil and have to be cleaned before further use. Supercritical carbon dioxide can be used for extraction processes and precision cleaning of metal parts, as developed at Forschungszentrum Karlsruhe. For optimizing and efficiently conducting the extraction process, in-line analysis of oil concentration is desirable. Therefore, a monitoring method using fiber-optic NIR spectroscopy in combination with PLS calibration has been developed. In an earlier paper we have described the instrumental set-up and a calibration model using the model compound squalane in the spectral range of the CH combination bands from 4900 to 4200cm(-1). With this model only poor prediction results were obtained if applied to technical oil samples in supercritical CO(2). In this paper we describe a new calibration model, which was set up for the squalane/carbon dioxide system covering the 323-353K temperature and the 16-35.6MPa pressure range. Here, calibration data in the spectral range from 6100 to 5030cm(-1) have been used. This range includes the 5100cm(-1) CO(2) band of the Fermi triad as well as the hydrocarbon 1st overtone CH stretching bands, where spectral features of oil compounds and squalane are more similar to each other. The root mean-squared error of prediction obtained with this model is 4mgcm(-3) for carbon dioxide and 0.4mgcm(-3) for squalane, respectively. The utilizability of the newly developed PLS calibration model for predicting the oil concentration and CO(2) density of solutions of technical oils in supercritical carbon dioxide has been tested. Three types of "real world" cutting and grinding oil formulations were used in these experiments. The calibration proved to be suitable for determining the technical oil concentration with an error of 1.1mgcm(-3) and the CO(2) density with an error of 6mgcm(-3). Therefore, it seems possible to apply this in-line analytical approach on

  14. Nanoparticles in the pharmaceutical industry and the use of supercritical fluid technologies for nanoparticle production.

    PubMed

    Sheth, Pratik; Sandhu, Harpreet; Singhal, Dharmendra; Malick, Waseem; Shah, Navnit; Kislalioglu, M Serpil

    2012-05-01

    Poor aqueous solubility of drug candidates is a major challenge for the pharmaceutical scientists involved in drug development. Particle size reduction appears as an effective and versatile option for solubility improvement. Nanonization is an attractive solution to improve the bioavailability of the poorly soluble drugs, improved therapies, in vivo imaging, in vitro diagnostics and for the production of biomaterials and active implants. In drug delivery, application of nanotechnology is commonly referred to as Nano Drug Delivery Systems (NDDS). In this article, commercially available nanosized drugs, their dosage forms and proprietors, as well as the methods used for preparation like milling, high pressure homogenization, vacuum deposition, and high temperature evaporation were listed. Unlike the traditional methods used for the particle size reduction, supercritical fluid-processing techniques offer advantages ranging from superior particle size control to clean processing. The primary focus of this review article is the use of supercritical CO2 based technologies for small particle generation. Particles that have the smooth surfaces, small particle size and distribution and free flowing can be obtained with particular SCF techniques. In almost all techniques, the dominating process variables may be thermodynamic and aerodynamic in nature, and the design of the particle collection environment. Rapid Expansion of Supercritical Solutions (RESS), Supercritical Anti Solvent (SAS) and Particles from Gas Saturated Solutions (PGSS) are three groups of processes which lead to the production of fine and monodisperse powders. Few of them may also control crystal polymorphism. Among the aforementioned processes, RESS involves dissolving a drug in a supercritical fluid (SCF) and passing it through an appropriate nozzle. Rapid depressurization of this solution causes an extremely rapid nucleation of the product. This process has been known for a long time but its application

  15. Method for nucleic acid isolation using supercritical fluids

    SciTech Connect

    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.

  16. 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.

  17. Stationary phases for packed-column supercritical fluid chromatography.

    PubMed

    Poole, Colin F

    2012-08-10

    The properties of silica-based, chemically bonded, packed column stationary phases used in supercritical fluid chromatography are described with a focus on column design and retention mechanisms. Supercritical fluid chromatography has benefited substantially from innovations in column design for liquid chromatography even if the separation conditions employed are generally quite different. The mobile phase composition and column operating conditions play an interactive role in modifying selectivity in supercritical fluid chromatography by altering analyte solubility in the mobile phase and through selective solvation of the stationary phase resulting in a wider range and intensity of intermolecular interactions with the analyte. The solvation parameter model is used to identify the main parameters that affect retention in supercritical fluid chromatography using carbon dioxide-methanol as a mobile phase and as a basis for column characterization to facilitate the identification of stationary phases with different separation characteristics for method development. As a caution it is pointed out that these column characterization methods are possibly a product of both the stationary phase chemistry and the column operating conditions and are suitable for use only when columns of similar design and with similar operating conditions are used.

  18. Determination of thermodynamic properties by supercritical fluid chromatography.

    PubMed

    Roth, Michal

    2004-05-28

    This survey attempts to summarise thermodynamic applications of supercritical fluid chromatography (SFC) with an emphasis on the results published during the last 10 years. In addition to a review of thermodynamic measurements by SFC, it contains brief sections on instrumental considerations and on the sources of auxiliary information needed when processing the retention data.

  19. 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.

  20. Capillary pressure-saturation relations in quartz and carbonate sands: Limitations for correlating capillary and wettability influences on air, oil, and supercritical CO2 trapping

    NASA Astrophysics Data System (ADS)

    Wang, Shibo; Tokunaga, Tetsu K.; Wan, Jiamin; Dong, Wenming; Kim, Yongman

    2016-08-01

    Capillary pressure (Pc)-saturation (Sw) relations are essential for predicting equilibrium and flow of immiscible fluid pairs in soils and deeper geologic formations. In systems that are difficult to measure, behavior is often estimated based on capillary scaling of easily measured Pc-Sw relations (e.g., air-water, and oil-water), yet the reliability of such approximations needs to be examined. In this study, 17 sets of brine drainage and imbibition curves were measured with air-brine, decane-brine, and supercritical (sc) CO2-brine in homogeneous quartz and carbonate sands, using porous plate systems under ambient (0.1 MPa, 23°C) and reservoir (12.0 MPa, 45°C) conditions. Comparisons between these measurements showed significant differences in residual nonwetting phase saturation, Snw_r. Through applying capillary scaling, changes in interfacial properties were indicated, particularly wettability. With respect to the residual trapping of the nonwetting phases, Snw_r, CO2 > Snw_r, decane > Snw_r, air. Decane-brine and scCO2-brine Pc-Sw curves deviated significantly from predictions assuming hydrophilic interactions. Moreover, neither the scaled capillary behavior nor Snw,r for scCO2-brine were well represented by decane-brine, apparently because of differences in wettability and viscosities, indicating limitations for using decane (and other organic liquids) as a surrogate fluid in studies intended to apply to geological carbon sequestration. Thus, challenges remain in applying scaling for predicting capillary trapping and multiphase displacement processes across such diverse fields as vadose zone hydrology, enhanced oil recovery, and geologic carbon sequestration.

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. Role of rock/fluid characteristics in carbon (CO2) storage and modeling

    USGS Publications Warehouse

    Verma, Mahendra K.

    2005-01-01

    The presentation ? Role of Rock/Fluid Characteristics in Carbon (CO2) Storage and Modeling ? was prepared for the meeting of the Environmental Protection Agency (EPA) in Houston, Tex., on April 6?7, 2005. It provides an overview of greenhouse gases, particularly CO2, and a summary of their effects on the Earth?s atmosphere. It presents methods of mitigating the effects of greenhouse gases, and the role of rock and fluid properties on CO2 storage mechanisms. It also lists factors that must be considered to adequately model CO2 storage.

  6. 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

  7. 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.

  8. 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.

  9. Effect of residence time on two-step liquefaction of rice straw in a CO2 atmosphere: Differences between subcritical water and supercritical ethanol.

    PubMed

    Yang, Tianhua; Wang, Jian; Li, Bingshuo; Kai, Xingping; Li, Rundong

    2017-04-01

    This study investigated the influence of temperature and residence time on liquefaction of rice straw in subcritical CO2-subcritical water (subCO2-subH2O) and in subcritical CO2-supercritical ethanol (subCO2-scEtOH), considering the final reaction temperatures (270-345°C) and residence times (15 and 30min). Residence time was identified as a crucial parameter in the subCO2-subH2O liquefaction, whereas residence time had a marginal influence on subCO2-scEtOH liquefaction. When reaction conditions were 320°C and 15min, solvents have weak impact on the quality of bio-oil, HHV 28.57MJ/kg and 28.62MJ/kg, respectively. There was an obvious difference between the subCO2-subH2O and subCO2-scEtOH liquefaction mechanisms. In subCO2-subH2O, CO2 promoted the carbonyl reaction. In subCO2-scEtOH, supercritical ethanol have the function of donating hydrogen and promoting the reaction of hydroxyl-alkylation.

  10. 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

  11. 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.

  12. 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.

  13. Statistical mechanical description of supercritical fluid extraction and retrograde condensation

    NASA Astrophysics Data System (ADS)

    Park, S. J.; Kwak, T. Y.; Mansoori, G. A.

    1987-07-01

    The phenomena of supercritical fluid extraction (SFE) and its reverse effect, which is known as retrograde condensation (RC), have found new and important applications in industrial separation of chemical compounds and recovery and processing of natural products and fossil fuels. Full-scale industrial utilization of SFE/RC processes requires knowledge about thermodynamic and transport characteristics of the asymmetric mixtures involved and the development of predictive modeling and correlation techniques for performance of the SFE/RC system under consideration. In this report, through the application of statistical mechanical techniques, the reasons for the lack of accuracy of existing predictive approaches are described and they are improved. It is demonstrated that these techniques also allow us to study the effect of mixed supercritical solvents on the solubility of heavy solutes (solids) at different compositions of the solvents, pressures, and temperatures. Fluid phase equilibrium algorithms based on the conformal solution van der Waals mixing rules and different equations of state are presented for the prediction of solubilities of heavy liquid in supercritical gases. It is shown that the Peng-Robinson equation of state based on conformal solution theory can predict solubilites of heavy liquid in supercritical gases more accurately than the van der Waals and Redlich-Kwong equations of state.

  14. Supercritical fluid processing of drug nanoparticles in stable suspension.

    PubMed

    Pathak, Pankaj; Meziani, Mohammed J; Desai, Tarang; Foster, Charles; Diaz, Julian A; Sun, Ya-Ping

    2007-07-01

    Significant effort has been directed toward the development of drug formulation and delivery techniques, especially for the drug of no or poor aqueous solubility. Among various strategies to address the solubility issue, the reduction of drug particle sizes to the nanoscale has been identified as a potentially effective and broadly applicable approach. Complementary to traditional methods, supercritical fluid techniques have found unique applications in the production and processing of drug particles. Here we report the application of a newly developed supercritical fluid processing technique, Rapid Expansion of a Supercritical Solution into a Liquid Solvent, to the nanosizing of potent antiparasitic drug Amphotericin B particles. A supercritical carbon dioxide-cosolvent system was used for the solubilization and processing of the drug. The process produced well-dispersed nanoscale Amphotericin B particles suspended in an aqueous solution, and the suspension was intrinsically stable or could be further stabilized in the presence of water-soluble polymers. The properties of the drug nanoparticles were found to be dependent on the type of cosolvent used. The results on the use of dimethyl sulfoxide and methanol as cosolvents and their effects on the properties of nanosized Amphotericin B particles are presented and discussed.

  15. 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

    2003-06-04

    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.

  16. Time-resolved remote Raman study of minerals under supercritical CO2 and high temperatures relevant to Venus exploration.

    PubMed

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

    2010-07-13

    We report time-resolved (TR) remote Raman spectra of minerals under supercritical CO(2) (approx. 95 atm pressure and 423 K) and under atmospheric pressure and high temperature up to 1003 K at distances of 1.5 and 9 m, respectively. The TR Raman spectra of hydrous and anhydrous sulphates, carbonate and silicate minerals (e.g. talc, olivine, pyroxenes and feldspars) under supercritical CO(2) (approx. 95 atm pressure and 423 K) clearly show the well-defined Raman fingerprints of each mineral along with the Fermi resonance doublet of CO(2). Besides the CO(2) doublet and the effect of the viewing window, the main differences in the Raman spectra under Venus conditions are the phase transitions, the dehydration and decarbonation of various minerals, along with a slight shift in the peak positions and an increase in line-widths. The dehydration of melanterite (FeSO(4).7H(2)O) at 423 K under approximately 95 atm CO(2) is detected by the presence of the Raman fingerprints of rozenite (FeSO(4).4H(2)O) in the spectrum. Similarly, the high-temperature Raman spectra under ambient pressure of gypsum (CaSO(4).2H(2)O) and talc (Mg(3)Si(4)O(10)(OH)(2)) indicate that gypsum dehydrates at 518 K, but talc remains stable up to 1003 K. Partial dissociation of dolomite (CaMg(CO(3))(2)) is observed at 973 K. The TR remote Raman spectra of olivine, alpha-spodumene (LiAlSi(2)O(6)) and clino-enstatite (MgSiO(3)) pyroxenes and of albite (NaAlSi(3)O(8)) and microcline (KAlSi(3)O(8)) feldspars at high temperatures also show that the Raman lines remain sharp and well defined in the high-temperature spectra. The results of this study show that TR remote Raman spectroscopy could be a potential tool for exploring the surface mineralogy of Venus during both daytime and nighttime at short and long distances.

  17. The latent heat of vaporization of supercritical fluids

    NASA Astrophysics Data System (ADS)

    Banuti, Daniel; Raju, Muralikrishna; Hickey, Jean-Pierre; Ihme, Matthias

    2016-11-01

    The enthalpy of vaporization is the energy required to overcome intermolecular attractive forces and to expand the fluid volume against the ambient pressure when transforming a liquid into a gas. It diminishes for rising pressure until it vanishes at the critical point. Counterintuitively, we show that a latent heat is in fact also required to heat a supercritical fluid from a liquid to a gaseous state. Unlike its subcritical counterpart, the supercritical pseudoboiling transition is spread over a finite temperature range. Thus, in addition to overcoming intermolecular attractive forces, added energy simultaneously heats the fluid. Then, considering a transition from a liquid to an ideal gas state, we demonstrate that the required enthalpy is invariant to changes in pressure for 0 < p < 3pcr . This means that the classical pressure-dependent latent heat is merely the equilibrium part of the phase transition. The reduction at higher pressures is compensated by an increase in a nonequilibrium latent heat required to overcome residual intermolecular forces in the real fluid vapor during heating. At supercritical pressures, all of the transition occurs at non-equilibrium; for p -> 0 , all of the transition occurs at equilibrium.

  18. Intermolecular interactions and the thermodynamic properties of supercritical fluids

    NASA Astrophysics Data System (ADS)

    Yigzawe, Tesfaye M.; Sadus, Richard J.

    2013-05-01

    The role of different contributions to intermolecular interactions on the thermodynamic properties of supercritical fluids is investigated. Molecular dynamics simulation results are reported for the energy, pressure, thermal pressure coefficient, thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient, and speed of sound of fluids interacting via both the Lennard-Jones and Weeks-Chandler-Andersen potentials. These properties were obtained for a wide range of temperatures, pressures, and densities. For each thermodynamic property, an excess value is determined to distinguish between attraction and repulsion. It is found that the contributions of intermolecular interactions have varying effects depending on the thermodynamic property. The maxima exhibited by the isochoric and isobaric heat capacities, isothermal compressibilities, and thermal expansion coefficient are attributed to interactions in the Lennard-Jones well. Repulsion is required to obtain physically realistic speeds of sound and both repulsion and attraction are necessary to observe a Joule-Thomson inversion curve. Significantly, both maxima and minima are observed for the isobaric and isochoric heat capacities of the supercritical Lennard-Jones fluid. It is postulated that the loci of these maxima and minima converge to a common point via the same power law relationship as the phase coexistence curve with an exponent of β = 0.32. This provides an explanation for the terminal isobaric heat capacity maximum in supercritical fluids.

  19. Atomistic molecular dynamics simulations of H2O diffusivity in liquid and supercritical CO2

    NASA Astrophysics Data System (ADS)

    Moultos, Othonas A.; Orozco, Gustavo A.; Tsimpanogiannis, Ioannis N.; Panagiotopoulos, Athanassios Z.; Economou, Ioannis G.

    2015-09-01

    Molecular dynamics simulations were employed for the calculation of diffusion coefficients of pure CO2 and of H2O in CO2 over a wide range of temperatures (298.15 K < T < 523.15 K) and pressures (5.0 MPa < P < 100.0 MPa), that are of interest to CO2 capture-and-sequestration processes. Various combinations of existing fixed-point-charge force-fields for H2O (TIP4P/2005 and Exponential-6) and CO2 (elementary physical model 2 [EPM2], transferable potentials for phase equilibria [TraPPE], and Exponential-6) were tested. All force-field combinations qualitatively reproduce the trends of the experimental data for infinitely diluted H2O in CO2; however, TIP4P/2005-EPM2, TIP4P/2005-TraPPE and Exponential-6-Exponential-6 were found to be the most consistent. Additionally, for H2O compositions ranging from infinite dilution to ?, the Maxwell-Stefan diffusion coefficient is shown to have a weak non-linear composition dependence.

  20. Microstructure of supercritical CO2-in-water microemulsions: a systematic contrast variation study.

    PubMed

    Klostermann, Michael; Foster, Tobias; Schweins, Ralf; Lindner, Peter; Glatter, Otto; Strey, Reinhard; Sottmann, Thomas

    2011-12-07

    Microemulsions of the type H(2)O-scCO(2)-surfactant are potential candidates for novel solvent mixtures in the field of green chemistry. Furthermore, scCO(2)-microemulsions are highly interesting from a fundamental point of view since their properties such as the bending elastic constants can be strongly influenced solely by varying the pressure without changing the components. With this motivation we studied the phase behavior and the microstructure of water-rich scCO(2)-microemulsions. Such microemulsions were formulated using the technical grade non-ionic surfactants Zonyl FSO 100 and Zonyl FSN 100. At elevated pressures the temperature dependent phase behavior of these systems follows the general patterns of non-ionic microemulsions. Small angle neutron scattering experiments were conducted to determine the length scales and the topology of the microstructure of these systems. Having determined the exact scattering length densities and the composition of the respective sub-phases by a systematic contrast variation we could show that these systems consist of CO(2)-swollen microemulsion droplets that are dispersed in a continuous aqueous-phase. The scattering data were analyzed using a newly derived form factor for polydisperse, spherical core/shell particles with diffuse interfaces. The underlying analytical density profiles could be confirmed applying the model-free Generalized Indirect Fourier Transformation (GIFT) to the scattering data. Following the general patterns of non-ionic microemulsions the radius of the microemulsion droplets is found to increase almost linearly upon the addition of CO(2).

  1. 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.

  2. Solubilities in supercritical fluids: the application of chromatographic measurement methods

    SciTech Connect

    Smith, R.D.; Udseth, H.R.; Wright, B.W.; Yonker, C.R.

    1987-01-01

    New methods are described for the measurement of the solubilities of solids in supercritical fluids. These methods utilize instrumentation developed for capillary supercritical fluid chromatography consisting of deactivated, small diameter, fused silica tubing, coupled with detection methods based upon on flame ionization and mass spectrometric detectors. The methods involve (a) direct solubility determination where the fused silica capillary is used as an equilibrium cell, and (b) a pressure of threshold solubility technique which resembles chromatography and uses a programmed pressure increase and sensitive detection to determine the onset of solute migration. Results are also presented which suggest that solubilities can be determined, within certain limitations, from actual chromatographic experiments. The methods are illustrated using aromatic hydrocarbons and complex mycotoxins of the trichothecene group.

  3. Supercritical fluid fractionation of petroleum- and coal-derived mixtures

    SciTech Connect

    Campbell, R.M.

    1987-01-01

    A supercritical fluid chromatography system was constructed to provide separations and fraction collection on a semi-preparative scale. A variety of complex mixtures were fractionated according to the number of aromatic rings using columns packed with NH/sub 2/-modified silica particles. Effluents were monitored with an ultraviolet spectrophotometer and a flame ionization detector while fractions were collected in pressurized vessels for subsequent analysis by capillary gas chromatography. A supercritical fluid chromatographic method to determine the percentage of saturates, olefins and aromatics in gasolines and middle distillate fuels was developed. A microbore silica column was used to isolate the aromatics, while a silver-loaded strong cation exchange microbore column was used to isolate the saturates Olefins were determined by difference. A flame ionization detector provided uniform, linear response for quantitation without calibration. The method was found to be accurate, rapid and reproducible.

  4. Micronization processes with supercritical fluids: fundamentals and mechanisms.

    PubMed

    Martín, A; Cocero, M J

    2008-02-14

    Supercritical fluid techniques for materials precipitation have been proposed as an alternative to conventional precipitation processes as they allow to improve the performance of these processes in terms of reduction of particle size and control of morphology and particle size distribution, without degradation or contamination of the product. These techniques have received much attention during the last years, and their feasibility and performance have been experimentally demonstrated for many substances. One of the main pending tasks is the development of a systematic procedure for the design and scale-up of these processes. This requires not only empirical knowledge, but also information about the fundamentals of the process. This work aims to review the published literature dealing with a fundamental investigation or modeling of supercritical fluid precipitation processes.

  5. Supercritical fluid extraction of all-trans-lycopene from tomato.

    PubMed

    Gómez-Prieto, M Salud; Caja, M Mar; Herraiz, Marta; Santa-María, Guillermo

    2003-01-01

    A procedure is proposed for the supercritical fluid extraction of all-trans-lycopene from tomato using carbon dioxide at 40 degrees C without modifier. The present method minimizes the risk of degradation via isomerization and oxidation of health-promoting ingredients, such as lycopene. The effect of different experimental variables on the solvating power of the supercritical fluid was evaluated in terms of both the selectivity achievable in the process and the yield of the extraction of all-trans-lycopene. Satisfactory separations of the all-trans-lycopene isomers from the cis counterparts were achieved using a C(30) column. The obtained extract contained 88% all-trans-lycopene and 12% cis-lycopene.

  6. The effect of CO2 and N2 on phase relations, fluid composition, and quartz solubility in amphibolite facies metamorphic rocks

    NASA Astrophysics Data System (ADS)

    Artimenko, Margaret V.

    2016-12-01

    Phase equilibria in the system SiO2-TiO2-Al2O3-Fe2O3-MnO-MgO-CaO-Na2O-K2O-P2O5-H2O-CO2-N2 are calculated to illustrate phase relations in amphibolite facies metasediments over a wide range of X[H2O-CO2-N2] conditions at 600 °C and 4.4 kb. Calculations are performed using the Gibbs free energy minimization technique. Results are presented in plots showing stable mineral assemblages as a function of total carbon in the system at varying water (a_{{{{H}}2 {{O}}}} = 1) content in the presence/absence of N2 in the fluid. The calculations indicate that the typical assemblage plagioclase—quartz—biotite—ilmenite—garnet—apatite is restricted to the rocks with CO2 saturation and X_{{{{H}}_{ 2} {{O}}}} higher than 60% in the fluid. Significant decrease in X_{{{{CO}}2 }} favors the stability of muscovite rather than garnet, whereas the decrease in X_{{{{H}}_{ 2} {{O}}}} leads to the stability of microcline over all range of X_{{{{CO}}2 }}. This paper also presents the composition and parameters (pH, Eh) of the fluid equilibrated with mineral assemblage. It is shown that the presence of low concentrations of N2 causes the fluid to consist of two phases when an aqueous supercritical solution (AS) coexists with a supercritical fluid with gas-like properties (SF). At high concentration of N2, the fluid consists of SF alone; in the absence of nitrogen, the fluid consists of AS alone. The solubility of monomer SiO 2 0 and dimer Si2O 4 0 decreases with increasing CO2 and after CO2 saturation point is held constant. The magnitude of the silica solubility at CO2 saturation depends upon the water content in AS. The effect of nitrogen on quartz solubility has been demonstrated to be negligible.

  7. Supercritical Fluid Extraction of Metal Chelate: A Review.

    PubMed

    Ding, Xin; Liu, Qinli; Hou, Xiongpo; Fang, Tao

    2017-03-04

    Supercritical fluid extraction (SFE), as a new green extraction technology, has been used in extracting various metal species. The solubilities of chelating agents and corresponding metal chelates are the key factors which influence the efficiency of SFE. Other main properties of them such as stability and selectivity are also reviewed. The extraction mechanisms of mainly used chelating agents are explained by typical examples in this paper. This is the important aspect of SFE of metal ions. Moreover, the extraction efficiencies of metal species also depend on other factors such as temperature, pressure, extraction time and matrix effect. The two main complexation methods namely in-situ and on-line chelating SFE are described in detail. As an efficient chelating agent, tributyl phosphate-nitric acid (TBP-HNO3) complex attracts much attention. The SFE of metal ions, lanthanides and actinides as well as organometallic compounds are also summarized. With the proper selection of ligands, high efficient extraction of metal species can be obtained. As an efficient sample analysis method, supercritical fluid chromatography (SFC) is introduced in this paper. Recently, the extraction method combining ionic liquids (ILs) with supercritical fluid has been becoming a novel technology for treating metal ions. The kinetics related to SFE of metal species is discussed with some specific examples.

  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.

  9. Synthesis and crystallization of titanium dioxide in supercritical carbon dioxide (scCO2)

    NASA Astrophysics Data System (ADS)

    Kaleva, A.; Heinonen, S.; Nikkanen, J.-P.; Levänen, E.

    2017-02-01

    In this work, a simple and low-temperature method to synthesize titanium dioxide (TiO2) particles with supercritical carbon dioxide is presented. The particles were synthesized by measuring 5 ml of tetra-n-butyl orthotitanate precursor to the supercritical chamber. The pressure was maintained at 15.0 MPafor all experiments. Reaction temperatures used were 50 °C or 70 °C. After reaching treatment parameters 10 ml of deionized water was introduced to the chamber with a co-solvent pump. A mixer was used inside the chamber to ensure proper mixing of water and precursor. Reaction times of 10, 60 and 300 min were used. Characterization of the particle crystal phase was determined by X-ray diffraction, differential scanning calorimetry and transmission electron microscopy. The specific surface areas were measured with nitrogen adsorption tests (BET). The results showed that the particles synthesized with reaction times of 10 and 60 min contained brookite as the crystalline phase. With longer reaction time of 300 min the phase shifted to anatase. In most experiments there was also significant amount of amorphous phase present. The specific surface areas varied between 274.3–566.6 m2/g.

  10. 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.

  11. Investigation of binary and ternary systems of ionic liquids with water and/or supercritical CO2 by in situ attenuated total reflection infrared spectroscopy.

    PubMed

    Andanson, Jean-Michel; Jutz, Fabian; Baiker, Alfons

    2010-02-18

    Two commonly used ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]), as well as binary and ternary mixtures of them with water and/or supercritical CO(2) (scCO(2)) were investigated by means of infrared spectroscopy at high pressure. The experiments were performed using attenuated total reflection (ATR) infrared spectroscopy on dry and wet ILs at 40 degrees C and pressures up to 150 bar of scCO(2). The studies indicate that the content of water does not change significantly the solubility of CO(2) in the ionic liquids tested. Furthermore, the presence of water does not change significantly the interaction between the IL anion and CO(2), which explains why the presence of water in IL does not modify the solubility of CO(2) in the system, even in the case of an initial molar ratio of approximately 50/50 of water in [bmim][BF(4)]. We show that despite the limited solubility of water in supercritical CO(2) an ionic liquid can be efficiently dried using scCO(2) extraction even in the case of a hydrophilic ionic liquid (e.g., [bmim][BF(4)]). During the scCO(2) extraction, the concentration of water was followed in situ using attenuated total reflection (ATR) infrared spectroscopy. After extraction, no residual water could be detected by this technique, which corresponds approximately to a water concentration of below 320 ppm.

  12. Near-infrared spectroscopic study of a water-in-supercritical CO2 microemulsion as a function of the water content.

    PubMed

    Takebayashi, Yoshihiro; Sagisaka, Masanobu; Sue, Kiwamu; Yoda, Satoshi; Hakuta, Yukiya; Furuya, Takeshi

    2011-05-19

    A water-in-supercritical CO(2) microemulsion is a reverse micelle encapsulating a nanometer-size water droplet dispersed in supercritical CO(2). In the microemulsion solution, water exists not only in the reverse micelle but also in the solvent CO(2). For quantitative analysis of the water distribution, near-infrared spectra of water + CO(2) and water + surfactant + CO(2) mixtures were measured over a wide range of water/CO(2) ratios from 0.1 to 1.0 wt% at 60 °C and 30.0 MPa. The stretching combination band of water was decomposed into two components, a sharp one peaked at 7194 cm(-1) assigned to monomeric water dissolved in CO(2) and a broad one around 7000 cm(-1) corresponding to aggregated water in the microemulsion. Integrated molar absorptivities of these types of water were negligibly different from each other, despite the different hydrogen-bonding environments. The spectral decomposition revealed that water is distributed mainly into CO(2) at water contents smaller than 0.5 wt% and then is introduced into the microemulsion after saturation of water in CO(2) and full hydration of the surfactant headgroup.

  13. Self-assembled inverted micelles stabilize ionic liquid domains in supercritical CO2.

    PubMed

    Chandran, Aneesh; Prakash, Karthigeyan; Senapati, Sanjib

    2010-09-08

    Molecular aggregation is a complex phenomenon that is difficult to study in detail experimentally. Here, we elucidate the formation of ionic liquid-in-carbon dioxide (IL-in-CO(2)) microemulsions via a computer simulation technique that demonstrates the entire process of self-aggregation at the atomic level. Our study reveals direct evidence of the existence of stable IL droplets within a continuous CO(2) phase through amphiphilic surfactants. The microstructure of the nanodroplets matches very well with the small-angle neutron scattering data. A detailed investigation of the structural and energetic properties explains why guanidium acetate-based IL-in-CO(2) microemulsions showed a greater stability than imidazolium hexafluorophosphate-based microemulsions in recent spectroscopic experiments. In contrast to the existing hypothesis in literature, the study reveals that the stability of the microemulsions mainly pertains to the IL anion-headgroup interactions, while the cations play a secondary role. The detailed atomic level understanding provides a deeper insight that could help in designing new surfactants for improved IL uptake in CO(2).

  14. Growing TiO2 nanowires on the surface of graphene sheets in supercritical CO2: characterization and photoefficiency

    NASA Astrophysics Data System (ADS)

    Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Chowdhury, Rajib Roy; Charpentier, Paul A.

    2012-07-01

    Tremendous interest exists towards synthesizing nanoassemblies for dye-sensitized solar cells (DSSCs) using earth-abundant and -friendly materials with green synthetic approaches. In this work, high surface area TiO2 nanowire arrays were grown on the surface of functionalized graphene sheets (FGSs) containing -COOH functionalities acting as a template by using a sol-gel method in the green solvent, supercritical carbon dioxide (scCO2). The effect of scCO2 pressure (1500, 3000 and 5000 psi), temperature (40, 60 and 80 °C), acetic acid/titanium isopropoxide monomer ratios (HAc/TIP = 2, 4 and 6), functionalized graphene sheets (FGSs)/TIP weight ratios (1:20, 1:40 and 1:60 w/w) and solvents (EtOH, hexane) were investigated. Increasing the HAc/TIPweight ratio from 4 to 6 in scCO2 resulted in increasing the TiO2 nanowire diameter from 10 to 40 nm. Raman and high resolution XPS showed the interaction of TiO2 with the -COOH groups on the surface of the graphene sheets, indicating that graphene acted as a template for polycondensation growth. UV-vis diffuse reflectance and photoluminescence spectroscopy showed a reduction in titania’s bandgap and also a significant reduction in electron-hole recombination compared to bare TiO2 nanowires. Photocurrent measurements showed that the TiO2nanowire/graphene composites prepared in scCO2 gave a 5× enhancement in photoefficiency compared to bare TiO2 nanowires.

  15. Growing TiO2 nanowires on the surface of graphene sheets in supercritical CO2: characterization and photoefficiency.

    PubMed

    Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Chowdhury, Rajib Roy; Charpentier, Paul A

    2012-07-27

    Tremendous interest exists towards synthesizing nanoassemblies for dye-sensitized solar cells (DSSCs) using earth-abundant and -friendly materials with green synthetic approaches. In this work, high surface area TiO(2) nanowire arrays were grown on the surface of functionalized graphene sheets (FGSs) containing -COOH functionalities acting as a template by using a sol-gel method in the green solvent, supercritical carbon dioxide (scCO(2)). The effect of scCO(2) pressure (1500, 3000 and 5000 psi), temperature (40, 60 and 80 °C), acetic acid/titanium isopropoxide monomer ratios (HAc/TIP = 2, 4 and 6), functionalized graphene sheets (FGSs)/TIP weight ratios (1:20, 1:40 and 1:60 w/w) and solvents (EtOH, hexane) were investigated. Increasing the HAc/TIPweight ratio from 4 to 6 in scCO(2) resulted in increasing the TiO(2) nanowire diameter from 10 to 40 nm. Raman and high resolution XPS showed the interaction of TiO(2) with the -COOH groups on the surface of the graphene sheets, indicating that graphene acted as a template for polycondensation growth. UV-vis diffuse reflectance and photoluminescence spectroscopy showed a reduction in titania's bandgap and also a significant reduction in electron-hole recombination compared to bare TiO(2) nanowires. Photocurrent measurements showed that the TiO(2)nanowire/graphene composites prepared in scCO(2) gave a 5× enhancement in photoefficiency compared to bare TiO(2) nanowires.

  16. 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.

  17. Effects of supercritical fluid extraction pressure on chemical composition, microbial population, polar lipid profile, and microstructure of goat cheese.

    PubMed

    Sánchez-Macías, D; Laubscher, A; Castro, N; Argüello, A; Jiménez-Flores, R

    2013-03-01

    The consumer trend for healthier food choices and preferences for low-fat products has increased the interest in low-fat cheese and nutraceutical dairy products. However, consumer preference is still for delicious food. Low- and reduced-fat cheeses are not completely accepted because of their unappealing properties compared with full-fat cheeses. The method reported here provides another option to the conventional cheese-making process to obtain lower fat cheese. Using CO(2) as a supercritical fluid offers an alternative to reduce fat in cheese after ripening, while maintaining the initial characteristics and flavor. The aim of this experiment was to evaluate the effect of pressure (10, 20, 30, and 40 × 10(6) Pa) of supercritical CO(2) on the amount of fat extracted, microbial population, polar lipid profile, and microstructure of 2 varieties of goat cheese: Majorero, a protected denomination of origin cheese from Spain, and goat Gouda-type cheese. The amount of fat was reduced 50 to 57% and 48 to 55% for Majorero and goat Gouda-type cheeses, respectively. Higher contents (on a fat basis) of sphingomyelin and phosphatidylcholine were found in Majorero cheese compared with control and goat Gouda-type cheeses. The microbial population was reduced after supercritical fluid extraction in both cheeses, and the lethality was higher as pressure increased in Majorero cheese, most noticeably on lactococcus and lactobacillus bacteria. The Gouda-type cheese did not contain any lactobacilli. Micrographs obtained from confocal laser scanning microscopy showed a more open matrix and whey pockets in the Majorero control cheese. This could explain the ease of extracting fat and reducing the microbial counts in this cheese after treatment with supercritical CO(2). Supercritical fluid extraction with CO(2) has great potential in the dairy industry and in commercial applications. The Majorero cheese obtained after the supercritical fluid extraction treatment was an excellent

  18. 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.

  19. Determination of N-nitrosamines in latex by sequential supercritical fluid extraction and derivatization.

    PubMed

    Reche, F; Garrigós, M C; Marín, M L; Jiménez, A

    2002-11-08

    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.

  20. 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)

  1. 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.

  2. 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

  3. 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...

  4. Peak distortions arising from large-volume injections in supercritical fluid chromatography.

    PubMed

    Dai, Yun; Li, Geng; Rajendran, Arvind

    2015-05-01

    Preparative separations in supercritical fluid chromatography (SFC) involve the injection of large volumes of the solute. In SFC, the mobile phase is typically high pressure CO2+modifier and the solute to be injected is usually dissolved in the modifier. Two-types of injection methods, modifier-stream and mixed-stream, are common in commercial preparative SFC systems. In modifier-stream injection, the injection is made in the modifier stream which is later mixed with the CO2 stream, while in the mixed-stream injection, the injection is made in a mixed CO2+modifier stream. In this work a systematic experimental and modelling study of the two techniques is reported using single-enantiomers of flurbiprofen on Chiralpak AD-H with CO2+methanol as the mobile phase. While modifier-stream injection shows non-distorted peaks, mixed-stream injection results in severe peak-distortion. By comparing the modelling and experimental results, it is shown that the modifier "plug" introduced in the mixed-stream injection is the primary cause of the peak distortions. The experimental results also point to the possible existence of viscous fingering which contributes to further peak distortion.

  5. The effect of processing variables on morphological and mechanical properties of supercritical CO2 foamed scaffolds for tissue engineering.

    PubMed

    White, Lisa J; Hutter, Victoria; Tai, Hongyun; Howdle, Steven M; Shakesheff, Kevin M

    2012-01-01

    The porous structure of a scaffold determines the ability of bone to regenerate within this environment. In situations where the scaffold is required to provide mechanical function, balance must be achieved between optimizing porosity and maximizing mechanical strength. Supercritical CO(2) foaming can produce open-cell, interconnected structures in a low-temperature, solvent-free process. In this work, we report on foams of varying structural and mechanical properties fabricated from different molecular weights of poly(DL-lactic acid) P(DL)LA (57, 25 and 15 kDa) and by varying the depressurization rate. Rapid depressurization rates produced scaffolds with homogeneous pore distributions and some closed pores. Decreasing the depressurization rate produced scaffolds with wider pore size distributions and larger, more interconnected pores. In compressive testing, scaffolds produced from 57 kDa P(DL)LA exhibited typical stress-strain curves for elastomeric open-cell foams whereas scaffolds fabricated from 25 and 15 kDa P(DL)LA behaved as brittle foams. The structural and mechanical properties of scaffolds produced from 57 kDa P(DL)LA by scCO(2) ensure that these scaffolds are suitable for potential applications in bone tissue engineering.

  6. Supercritical CO(2)-extracted tomato Oleoresins enhance gap junction intercellular communications and recover from mercury chloride inhibition in keratinocytes.

    PubMed

    Leone, Antonella; Zefferino, Roberto; Longo, Cristiano; Leo, Lucia; Zacheo, Giuseppe

    2010-04-28

    A nutritionally relevant phytochemical such as lycopene, found in tomatoes and other fruits, has been proposed to have health-promoting effects by modulating hormonal and immune systems, metabolic pathways, and gap junction intercellular communication (GJIC). This work analyzes lycopene extracts, obtained from tomato and tomato added with grape seeds by using a safe and environmentally friendly extraction process, based on supercritical carbon dioxide technology (S-CO(2)). Analysis of the innovative S-CO(2)-extracted oleoresins showed peculiar chemical composition with high lycopene concentration and the presence of other carotenoids, lipids, and phenol compounds. The oleoresins showed a higher in vitro antioxidant activity compared with pure lycopene and beta-carotene and the remarkable ability to enhance the GJIC and to increase cx43 expression in keratinocytes. The oleoresins, (0.9 microM lycopene), were also able to overcome, completely, the GJIC inhibition induced by 10 nM HgCl(2), mercury(II) chloride, suggesting a possible action mechanism.

  7. Application of supercritical fluid carbon dioxide to the extraction and analysis of lipids.

    PubMed

    Lee, Jae Won; Fukusaki, Eiichiro; Bamba, Takeshi

    2012-10-01

    Supercritical carbon dioxide (SCCO(2)) is an ecofriendly supercritical fluid that is chemically inert, nontoxic, noninflammable and nonpolluting. As a green material, SCCO(2) has desirable properties such as high density, low viscosity and high diffusivity that make it suitable for use as a solvent in supercritical fluid extraction, an effective and environment-friendly analytical method, and as a mobile phase for supercritical fluid chromatography, which facilitates high-throughput, high-resolution analysis. Furthermore, the low polarity of SCCO(2) is suitable for the extraction and analysis of hydrophobic compounds. The growing concern surrounding environmental pollution has triggered the development of green analysis methods based on the use of SCCO(2) in various laboratories and industries. SCCO(2) is becoming an effective alternative to conventional organic solvents. In this review, the usefulness of SCCO(2) in supercritical fluid extraction and supercritical fluid chromatography for the extraction and analysis of lipids is described.

  8. 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.

  9. 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.

  10. 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

  11. Experimental Determination of Clay Mineral Reactions in Clastic Reservoir Rock Resulting from the Injection of Supercritical CO2

    NASA Astrophysics Data System (ADS)

    Mangini, S. A.; Shaw, C. A.; Skidmore, M. L.

    2013-12-01

    The Cretaceous Frontier Formation of the Powder River Basin, WY has been considered as a potential reservoir for storing anthropogenic CO2. The reservoir zones are composed of fine-grained quartz and potassium feldspar rich sandstones, cemented with clay minerals (kaolinite and interlayered illite and montmorillonite). The purpose of these experiments is to determine whether susceptible minerals such as illite, montmorillonite, and potassium feldspar undergo in-situ 'weathering' reactions when exposed to the high concentrations of carbonic acid generated by the dissolution of supercritical CO2 in formation water. The transformation of these minerals has the potential to: 1.) open up pore space through dissolution; 2.) reduce pore space and/or close pore throats by precipitating new minerals, or 3.) cause little change if the reactions take place slowly. Core samples of the Frontier Formation were obtained from the USGS Core Repository in Denver, CO and their physical and mineralogical properties analyzed. Porosity and permeability of the cores have been determined by helium porosimetry and gas permeability testing. Pore space distribution was analyzed by CT scan. Mineralogy was determined by thin section analysis, X-Ray diffraction, and Scanning Electron Microscopy. Ongoing experiments will expose the cores to CO2 saturated brine in a flow-through reactor at conditions similar to those found in the subsurface (100oC and 15MPa). Changes to the chemical composition of the brine will be determined by withdrawing samples at regular intervals during the experiment and analyzing their contents with ion chromatography and colorimetry. The physical and mineralogical properties of the cores will be analyzed after each experiment and compared to the initial conditions. We will report on the results of these experiments.

  12. 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.

  13. Proapoptotic and antimetastatic properties of supercritical CO2 extract of Nigella sativa Linn. against breast cancer cells.

    PubMed

    Baharetha, Hussein M; Nassar, Zeyad D; Aisha, Abdalrahim F; Ahamed, Mohamed B Khadeer; Al-Suede, Foaud Saleih R; Abd Kadir, Mohd Omar; Ismail, Zhari; Majid, Amin Malik Shah Abdul

    2013-12-01

    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.

  14. 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.

  15. Investigation of Multiphase Modeling Approaches for Behavior of Super Critical CO2 in Deep Formations Using Analog Fluids in the Laboratory

    NASA Astrophysics Data System (ADS)

    Trevisan, L.; Illangasekare, T. H.; Agartan, E.; Mori, H.; Cihan, A.; Birkholzer, J. T.; Zhou, Q.

    2013-12-01

    Investigation of supercritical carbon dioxide (scCO2) injection and migration in the laboratory is challenging due to difficulties in recreating the high pressures that exist in deep formations, influencing physicochemical properties of the fluid phases. Experimental simulation of scCO2 injection into deep saline formations can be performed under ambient pressure conditions in the laboratory scale by using combinations of analog fluids that mimic the flow dynamics of the phases involved in the actual scCO2 injection and migration in saline aquifers. In this study, dimensional analysis is used to describe the interplay of relevant forces acting on the fluid system during experiments conducted in a synthetic aquifer. The two-dimensional component of the experiment enables a qualitative estimation of the sweep efficiency, while a glycerol-water mixture and an isoparaffin solvent represent the displaced and invading phases, respectively. Viscosity and density ratios of this analog fluid combination are maintained consistent with brine and scCO2 in deep geologic formations. We present an experimental study of scCO2 injection and migration using a 3 ft x 2 ft synthetic quasi-2D aquifer aimed to quantify capillary entrapment factoring in hysteresis effects. Compared to one-dimensional core-flooding tests, the range of initial and residual non-wetting phase saturations at the end of the primary drainage and main imbibition stages in our experiments allows determination of the trapping curve through only one experiment. Finally, a numerical model with TOUGH2-T2VOC is used to simulate the experiments with analog fluids. Afterwards, a self-similar numerical model with TOUGH2-ECO2N simulating reservoir fluids is compared to the model with analog fluids in order to establish a link between the experimental scale and the field scale.

  16. 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

  17. Supercritical fluid extraction and direct fluid injection mass spectrometry for the determination of trichothecene mycotoxins in wheat samples

    SciTech Connect

    Kalinoski, H.T.; Udseth, H.R.; Wright, B.W.; Smith, R.D.

    1986-10-01

    The application of on-line supercritical fluid extraction with chemical ionization mass spectrometry and collision induced dissociation tandem mass spectrometry for the rapid identification of parts-per-million levels of several trichothecene mycotoxins is demonstrated. Supercritical carbon dioxide is shown to allow identification of mycotoxins with minimum sample handling in complex natural matrices (e.g., wheat). Tandem mass spectrometry techniques are employed for unambiguous identification of compounds of varying polarity, and false positives from isobaric compounds are avoided. Capillary column supercritical fluid chromatography-mass spectrometry of a supercritical fluid extract of the same sample was also performed and detection limits in the parts-per-billion range appear feasible.

  18. 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.

  19. 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%.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  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. 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

  8. Optimization of parameters for the supercritical fluid extraction in the determination of N-nitrosamines in rubbers.

    PubMed

    Rech, F; Garrigós, M C; Marín, M L; Cantó, A; Jiménez, A

    2002-07-19

    The study of the possibilities of supercritical fluid extraction (SFE) with N-nitrosamines in rubbers has been carried out. Home-made materials fortified with several N-nitrosamines were prepared in order to optimize the SFE parameters. A Plackett-Burman design was employed to evaluate the influence of those parameters to be controlled in SFE, such as pressure, temperature, static and dynamic time, restrictor temperature and volume of modifier while CO2 was used as the extraction fluid. An extra central composite design for the main factors (according to the previously obtained results) was also developed in order to refine the best supercritical conditions for the extraction of N-nitrosamines from rubbers. Gas chromatography with a nitrogen and phosphorus sensitive detector was used to achieve sensitivity and limits of detection for the concentrations expected in plastic materials. The proposed analytical method has shown to be useful in the determination of N-nitrosamines even for complex matrices.

  9. Conductivity measurements on H2O-bearing CO2-rich fluids

    DOE PAGES

    Capobianco, Ryan M.; Miroslaw S. Gruszkiewicz; Bodnar, Robert J.; ...

    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

  10. Continuous N-alkylation reactions of amino alcohols using γ-Al2O3 and supercritical CO2: unexpected formation of cyclic ureas and urethanes by reaction with CO2

    PubMed Central

    Streng, Emilia S; Lee, Darren S

    2017-01-01

    The use of γ-Al2O3 as a heterogeneous catalyst in scCO2 has been successfully applied to the amination of alcohols for the synthesis of N-alkylated heterocycles. The optimal reaction conditions (temperature and substrate flow rate) were determined using an automated self-optimising reactor, resulting in moderate to high yields of the target products. Carrying out the reaction in scCO2 was shown to be beneficial, as higher yields were obtained in the presence of CO2 than in its absence. A surprising discovery is that, in addition to cyclic amines, cyclic ureas and urethanes could be synthesised by incorporation of CO2 from the supercritical solvent into the product. PMID:28326142

  11. 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.

  12. 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.

  13. Determination of solvation kinetics in supercritical fluids. Project summary, August 15, 1993--May 3, 1994

    SciTech Connect

    Bright, F.V.

    1994-08-01

    This project is directed on determining effects of supercritical fluids on salvation and chemical reactions. Sub-projects are: understanding the effects of neat and entrainer-modified supercritical fluids on solute-fluid interactions; determining the influence of supercritical fluids on energetics and dynamics of solute conformation; and probing effects of continuous phase density on internal dynamics of reverse micelles formed in supercritical fluids. In order to follow these fast molecular-level processes, modern picosecond in-situ optical spectroscopy is being used. To date this work has: helped define how ``diffusion controlled`` reactions proceed in supercritical fluids; determined how and on what time scale entrainers preferentially solvate solutes in the near-critical region; shown that the conformation (i.e., reactivity) of flexible solutes can be altered easily with fluid density; shown how lateral diffusion within reverse micelles (formed in supercritical alkanes) is affected by the continuous phase density; and begun to probe how the conformation of polymers can be controlled with supercritical fluids. This is leading to a better molecular-level understanding of the chemistry of supercritical fluids.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Evaluation of the composition of Carica papaya L. seed oil extracted with supercritical CO2.

    PubMed

    Barroso, Pedro T W; de Carvalho, Pedro P; Rocha, Thiago B; Pessoa, Fernando L P; Azevedo, Debora A; Mendes, Marisa F

    2016-09-01

    Among the most important tropical fruit grown in the world today and in Brazil, papaya occupies a prominent place. Native to tropical America, papaya has spread to several regions of the world, and Brazil accounts for 12.74% of the world production, followed by Mexico, Nigeria and India. The culture reached a harvested area of 441,042 ha and production of 12,420,585 t worldwide. The largest interest in this fruit relies on its main constituent compounds, like vitamins A, B and C, alkaloids (carpaine and pseudocarpaine), proteolytic enzymes (papain and quimiopapain) and benzyl isothiocyanate, more known as BITC, which has anthelmintic activity. Because of that, the present work has as objective the evaluation of the efficiency and composition of the oil extracted from Carica papaya L. seeds with supercritical carbon dioxide. The experiments were performed in a unit containing mainly a high-pressure pump and a stainless steel extractor with 42 mL of volume. The sampling was performed at each 20 min until the saturation of the process. About 6.5 g of sample were fed for each experiment done at 40, 60 and 80 °C under the pressures of 100, 150 and 200 bar. Samples of the Carica papaya L. fruit were acquired in a popular market and free for personal use intended for the study. After collection, the seeds were crushed with the help of a pestle, and dried at 60 °C for 60 min. For each operational condition, the extraction curves were constructed relating cumulative mass of oil extracted in function of the operational time. The better efficiencies were found at 40 °C and 200 bar (1.33%) followed by 80 °C and 200 bar (2.56%). Gas chromatography and NMR analysis could identify an insecticide component (BITC) that enables new applications of this residue in pharmaceutical and chemical industries.

  19. Supercritical fluid extraction of particulate and adsorbent materials. Part 2. Final report, February 1985-January 1986

    SciTech Connect

    Wright, B.W.; Smith, R.D.

    1987-12-01

    The physical properties of supercritical fluids allow similar solvent strengths as liquids, but with higher diffusion coefficients, lower viscosities, and an extended temperature range that provides the potential for more-rapid and efficient extraction rates than possible with liquids. The report describes expanded studies conducted to evaluate the applicability and efficiency of analytical supercritical fluid extraction and related methodologies. These studies included the development of quantitative off-line supercritical fluid extraction methodology and a comparison to traditional Soxhlet extraction, the development and evaluation of on-line supercritical fluid extraction-gas chromatography for combined sample preparation and analysis, and direct supercritical fluid extraction-mass spectrometry for the monitoring of specific extraction profiles as a function of time. The sample matrices included an air particulate sample and XAD-2 resin, polyurethane foam, and Spherocarb adsorbents that were spiked with various model compounds. Carbon dioxide, isobutane, and methanol modified (20 mole %) carbon dioxide were utilized as supercritical fluid systems. Related studies on the evaluation of the quantitative analysis capability of a fluorescence detection supercritical fluid chromatography method and the development of viable solute focusing methods for capillary supercritical fluid chromatography were also conducted.

  20. On-line coupling of supercritical fluid extraction and chromatographic techniques.

    PubMed

    Sánchez-Camargo, Andrea Del Pilar; Parada-Alfonso, Fabián; Ibáñez, Elena; Cifuentes, Alejandro

    2017-01-01

    This review summarizes and discusses recent advances and applications of on-line supercritical fluid extraction coupled to liquid chromatography, gas chromatography, and supercritical fluid chromatographic techniques. Supercritical fluids, due to their exceptional physical properties, provide unique opportunities not only during the extraction step but also in the separation process. Although supercritical fluid extraction is especially suitable for recovery of non-polar organic compounds, this technique can also be successfully applied to the extraction of polar analytes by the aid of modifiers. Supercritical fluid extraction process can be performed following "off-line" or "on-line" approaches and their main features are contrasted herein. Besides, the parameters affecting the supercritical fluid extraction process are explained and a "decision tree" is for the first time presented in this review work as a guide tool for method development. The general principles (instrumental and methodological) of the different on-line couplings of supercritical fluid extraction with chromatographic techniques are described. Advantages and shortcomings of supercritical fluid extraction as hyphenated technique are discussed. Besides, an update of the most recent applications (from 2005 up to now) of the mentioned couplings is also presented in this review.

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. Effects of seawater pCO2 changes on the calcifying fluid of scleractinian corals

    NASA Astrophysics Data System (ADS)

    Hohn, S.; Merico, A.

    2012-03-01

    Rising atmospheric CO2 concentrations due to anthropogenic emissions induce changes in the ocean carbonate chemistry and a drop in ocean pH. This acidification process is expected to harm calcifying organisms like coccolithophores, molluscs, echinoderms, and corals. A severe decline in coral abundance is, for example, expected by the end of this century with associated disastrous effects on reef ecosystems. Despite the growing importance of the topic, little progress has been made with respect to modelling the impact of acidification on coral calcification. Here we present a model for a coral polyp that simulates the carbonate system in four different compartments: the seawater, the polyp tissue, the coelenteron, and the calicoblastic layer. Precipitation of calcium carbonate takes place in the metabolically controlled calicoblastic layer beneath the polyp tissue. The model is adjusted to a state of activity as observed by direct microsensor measurements in the calcifying fluid. Simulated CO2 perturbation experiments reveal decreasing calcification rates under elevated pCO2 despite strong metabolic control of the calcifying fluid. Diffusion of CO2 through the tissue into the calicoblastic layer increases with increasing seawater pCO2 leading to decreased aragonite saturation in the calcifying fluid of the coral polyp. Our modelling study provides important insights into the complexity of the calcification process at the organism level and helps to quantify the effect of ocean acidification on corals.

  6. Comparison of supercritical fluid and Soxhlet extractions for the isolation of nitro compounds from soils.

    PubMed

    Bajerová, Petra; Eisner, Ales; Jezová, Vera; Adam, Martin; Ventura, Karel

    2008-05-01

    Supercritical fluid extraction (SFE) with CO(2), a clean and rapid alternative to conventional Soxhlet extraction, was investigated for the extraction of nitro compounds from soil samples. Quantitative extraction by SFE was accomplished at a pressure of 25 MPa and an extraction temperature of 60 degrees C, for 30 min in dynamic mode and using acetonitrile as modifier, and the results were comparable with those obtained by acetonitrile Soxhlet extraction (3 h) for all soil samples. Extracts from these two procedures were analyzed by gas chromatography coupled with mass spectrometry. Quantitative reproducibility for SFE extracts was acceptable (RSD 2-10%), and the quantity of solvent was reduced from 160 mL for Soxhlet extraction to 5 mL in the case of SFE.

  7. Free-standing arrays of isolated TiO2 nanotubes through supercritical fluid drying.

    PubMed

    Deneault, James R; Xiao, Xiaoyin; Kang, Tae-Sik; Wang, Joanna S; Wai, Chien M; Brown, Gail J; Durstock, Michael F

    2012-01-16

    A common complication in fabricating arrays of TiO(2) nanotubes is that they agglomerate into tightly packed bundles during the inevitable solvent evaporation step. This problem is particularly acute for template-fabricated TiO(2) nanotubes, as the geometric tunability of this technique enables relatively large inter-pore spacings or, from another perspective, more space for lateral displacement. Our work showed that agglomeration results from the surface tension forces that are present as the ambient solvent is evaporated from the nanotube film. Herein, we report a processing and fabrication approach that utilizes supercritical fluid drying (CO(2)) to prepare arrays of template-fabricated TiO(2) nanotubes that are free-standing and spatially isolated. This approach could be beneficial to many emerging technologies, such as solid-state dye-sensitized solar cells and vertically-oriented carbon nanotube electrodes.

  8. 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.

  9. 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

  10. Prospects of Supercritical Fluids in Realizing Graphene-Based Functional Materials.

    PubMed

    Padmajan Sasikala, Suchithra; Poulin, Philippe; Aymonier, Cyril

    2016-04-13

    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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Application of supercritical CO(2) extraction for the elimination of odorant volatile compounds from winemaking inactive dry yeast preparation.

    PubMed

    Pozo-Bayón, María Angeles; Andújar-Ortiz, Inmaculada; Mendiola, Jose A; Ibáñez, Elena; Moreno-Arribas, M Victoria

    2010-03-24

    A procedure based on the application of supercritical CO(2) extraction to reduce and/or to remove odorant volatile compounds from a winemaking inactive dry yeast (IDY) preparation has been set up. By applying a factorial design, a screening of different temperatures and pressure conditions was assayed in order to determine the optimal deodorization conditions, and afterward the effect of several sample pretreatments was investigated. The best extraction conditions were achieved at 200 atm and 60 degrees C, applying the cryogenic grinding of the sample and using 40% (w/w) ethanol as cosolvent. By using these conditions, it was possible to reduce to approximately 70% of the volatile compounds present in the samples that may be released into the wines and therefore affecting their sensory characteristics. Odorant volatile compounds such as 2-methylhydroxypyrrole, 2-ethyl-6-methylpyrazine, and 2,3,5-trimethylpyrazine completely disappeared from the deodorized sample as verified by GC-O analysis. Additional experiments in model wines confirmed the low release of volatile compounds from the deodorized samples, without provoking any change to their nonvolatile composition (nitrogen compounds and neutral polysaccharides) that is related to the technological properties of these preparations.

  16. 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.

  17. Leavened dough processing by supercritical fluid extrusion (SCFX).

    PubMed

    Hicsasmaz, Zeynep; Dogan, Esref; Chu, Cindy; Rizvi, Syed S H

    2003-10-08

    Yeast-leavened dough processing is semicontinuous due to the requirement for fermentation at constant temperature and humidity. Also, new regulations on the emission of alcohols are becoming burdensome on the baking industry. Extrusion processing of dough with supercritical carbon dioxide (SC-CO(2)) is envisioned to alleviate emission problems and to decrease production time by eliminating fermentation. A bread dough formulation with 50% (w/w) moisture was leavened by injecting 1.5% (w/w) SC-CO(2) in a twin-screw extruder at 37 degrees C. Specific mechanical energy input was 260 kJ/kg. The operating apparent shear rate range was 60-260 s(-1). SCFX-leavened dough density (420-430 kg/m(3)) was in good agreement with values reported for similar doughs. The flow behavior index, obtained by an on-line slit rheometer, was 0.49 for the nonleavened control and 0.63 for the SCFX-leavened dough. Apparent viscosity of the SCFX-leavened dough varied from 37 to 23 Pa-s. This new continuous process offers attractive possibilities for industrial applications if further developed.

  18. Supercritical fluid and Soxhlet extractions of organics from sediments

    SciTech Connect

    Riley, R.G.; Sklarew, D.S.; Ozanich, R.M.; Lee, R.N.; Amonette, J.E.; Wright, B.W.

    1995-10-01

    The authors evaluated solvent consumption, atmospheric emissions, and waste generation as factors contributing to environmental, safety, and health issues associated with the extraction of organic materials from sediments when commercially available supercritical fluid extraction (SFE) and Soxhlet extraction systems are used. They found that the Soxhlet system used 10 times as much solvent as the SFE system and released about 6 times the volume of solvent into the atmosphere. Although the total volume of solvent released was much greater for Soxhlet than for SFE extractions, the mean concentration of solvent in the exhaust air from operation of SFE was about 10 times higher because the SFE extraction was much quicker (40 min vs. 18--24 h). As a consequence, operation of Soxhlet or SFE systems under conditions that do not control vapor releases could lead to air concentrations that exceed threshold limit values (TLVs) provided as guidelines for industrial exposure. The releases at facility stacks could also exceed the ambient air concentration limits for hazardous chemicals. Soxhlet systems produced significant liquid waste and some solid hazardous waste. Although components of the SFE process did not produce any liquid waster, they did produce solid waste that may be hazardous unless the solvent modifiers are carefully selected and their concentrations controlled in the supercritical fluid.

  19. Pushing the speed limit in enantioselective supercritical fluid chromatography.

    PubMed

    Regalado, Erik L; Welch, Christopher J

    2015-08-01

    Chromatographic enantioseparations on the order of a few seconds can be achieved by supercritical fluid chromatography using short columns packed with chiral stationary phases. The evolution of 'world record' speeds for the chromatographic separation of enantiomers has steadily dropped from an industry standard of 20-40 min just two decades ago, to a current ability to perform many enantioseparations in well under a minute. Improvements in instrument and column technologies enabled this revolution, but the ability to predict optimal separation time from an initial method development screening assay using the t(min cc) predictor greatly simplifies the development and optimization of high-speed chiral chromatographic separations. In this study, we illustrate how the use of this simple tool in combination with the workhorse technique of supercritical fluid chromatography on customized short chiral columns (1-2 cm length) allows us to achieve ultrafast enantioseparations of pharmaceutically relevant compounds on the 5-20 s scale, bringing the technique of high-throughput enantiopurity analysis out of the specialist realm and into the laboratories of most researchers.

  20. Supercritical-fluid extraction and chromatography-mass spectrometry for analysis of mycotoxins

    SciTech Connect

    Smith, R.D.; Udseth, H.R.

    1982-07-01

    The use of direct supercritical-fluid injection-mass spectrometry for the rapid analysis of mycotoxins of the tricothecene group is demonstrated. A solution containing diacetoxyscirpenol or T-2 toxin is injected into a fluid consisting primarily of pentane or carbon dioxide and is rapidly brought to supercritical conditions. Direct injection of the fluid stream into a chemical ionization source allows thermally labile compounds to be analyzed. Under these conditions trichothecene mass spectra showing significant (M + 1)/sup +/ ions and distinctive fragmentation patterns are obtained. Detection limits are in the subnanogram range. Direct analysis from complex substrates using selective supercritical-fluid extraction is proposed. 4 figures.

  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. 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.

  3. 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

  4. Effects of supercritical fluid chromatography conditions on enantioselectivity and performance of polyproline-derived chiral stationary phases.

    PubMed

    Novell, Arnau; Méndez, Alberto; Minguillón, Cristina

    2015-07-17

    The chromatographic behaviour and performance of four polyproline-derived chiral stationary phases (CSPs) were tested using supercritical fluid chromatography (SFC). A series of structurally related racemic compounds, whose enantioseparation was proved to be sensitive to the type of mobile phase used in NP-HPLC, were chosen to be tested in the SFC conditions. Good enantioselection ability was shown by the CSPs for the analytes tested in the new conditions. Resolution, efficiency and analysis time, were considerably improved with respect to NP-HPLC when CO2/alcohol mobile phases were used. Monolithic columns clearly show enhanced chromatographic parameters and improved performance respect to their bead-based counterparts.

  5. Assay of tolnaftate and related impurities by isocratic supercritical fluid chromatography.

    PubMed

    Patil, S T; Bhoir, I C; Bhagwat, A M; Sundaresan, M

    2000-05-01

    Tolnaftate, an antifungal drug (TF) and related impurities arising from synthesis, viz., N-methyl-m-toluidine (NMmT) and beta-naphthol-1-chlorothio carbamate (beta-NCTC) can be determined by supercritical fluid chromatography. Even though it was possible to elute TF completely with neat SCF CO2, the peaks of the impurities were found to merge. The chromatographic figures of merit of the three analytes such as retention time (tR), capacity factor (k), selectivity factor (alpha), no. of theoretical plates (N), were optimized. The three compounds can be resolved in 5 min on a Hypersil (250 x 4.0 mm) 5 mu, C18 column with supercritical carbon dioxide, modified with 1.96% methanol as the mobile phase at 9.81 MPa and at 40 degrees C. Detection was carried out at 220 nm. The data as evaluated by the linear regression least squares fit method gave linearity ranges from 0.2 to 10.0 microg/mL for TF and NMmT and 0.3 to 10.0 microg/mL for beta-NCTC with correlation coefficients > 0.99. The method was successfully employed to estimate levels of 0.01% for NMmT and 0.02% for beta-NCTC with respect to TF.

  6. 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.

  7. 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.

  8. Formation of methotrexate-PLLA-PEG-PLLA composite microspheres by microencapsulation through a process of suspension-enhanced dispersion by supercritical CO2

    PubMed Central

    Chen, Ai-Zheng; Wang, Guang-Ya; Wang, Shi-Bin; Li, Li; Liu, Yuan-Gang; Zhao, Chen

    2012-01-01

    Background The aim of this study was to improve the drug loading, encapsulation efficiency, and sustained-release properties of supercritical CO2-based drug-loaded polymer carriers via a process of suspension-enhanced dispersion by supercritical CO2 (SpEDS), which is an advanced version of solution-enhanced dispersion by supercritical CO2 (SEDS). Methods Methotrexate nanoparticles were successfully microencapsulated into poly (L-lactide)-poly(ethylene glycol)-poly(L-lactide) (PLLA-PEG-PLLA) by SpEDS. Methotrexate nanoparticles were first prepared by SEDS, then suspended in PLLA-PEG-PLLA solution, and finally microencapsulated into PLLA-PEG-PLLA via SpEDS, where an “injector” was utilized in the suspension delivery system. Results After microencapsulation, the composite methotrexate (MTX)-PLLA-PEG-PLLA microspheres obtained had a mean particle size of 545 nm, drug loading of 13.7%, and an encapsulation efficiency of 39.2%. After an initial burst release, with around 65% of the total methotrexate being released in the first 3 hours, the MTX-PLLA-PEG-PLLA microspheres released methotrexate in a sustained manner, with 85% of the total methotrexate dose released within 23 hours and nearly 100% within 144 hours. Conclusion Compared with a parallel study of the coprecipitation process, microencapsulation using SpEDS offered greater potential to manufacture drug-loaded polymer microspheres for a drug delivery system. PMID:22787397

  9. A Supercritical Fluid Chromatography/Tandem Mass Spectrometry Method for the Simultaneous Quantification of Metformin and Gliclazide in Human Plasma

    PubMed Central

    Agrawal, Y. K.; Gogoi, P. J.; Manna, K.; Bhatt, H. G.; Jain, V. K.

    2010-01-01

    Present study reports the development and validation of a simultaneous estimation of metformin and gliclazide in human plasma using supercritical fluid chromatography followed by tandem mass spectrometry. Acetonitrile:water (80:20) mixture was used as a mobile phase along with liquid CO2 in supercritical fluid chromatography and phenformin as an internal standard. The modified plasma samples were analyzed by electro-spray ionization method in selective reaction monitoring mode in tandem mass spectrometry. Supercritical fluid chromatographic separation was performed using nucleosil C18 containing column as a stationary phase. The separated products were identified by characteristic peaks and specific fragments peaks in tandem mass spectrometry as m/z 130 to 86 for metformin, m/z 324 to 110 for gliclazide and m/z 206 to 105 for phenformin. The present method was found linear in the concentration ranges of 6.0-3550 ng/ml and 7.5-7500 ng/ml for metformin and gliclazide, respectively. Pharmacokinetic study was performed after an oral administration of dispersible tablets containing 500 mg of metformin and 80 mg of gliclazide using same techniques. PMID:20582190

  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. Supercritical fluid chromatography for the separation of isoflavones.

    PubMed

    Ganzera, Markus

    2015-03-25

    The first protocol for the analysis of isoflavones by supercritical fluid chromatography is reported. Optimum results were obtained on an Acquity UPC(2) BEH 1.7 μm column, using a solvent gradient of supercritical carbon dioxide and methanol (with phosphoric acid as additive) for elution. The method enables the baseline separation of nine isoflavones (aglyca and glycosides) in 8 min, and is suitable for their quantitative determination in dietary supplements containing soy (Glycine max), red glover (Trifolium pratense) and kudzu (Pueraria lobata). Method validation confirmed that the assay is selective, linear (R(2)≥0.9994), accurate (recovery rates from 97.6 to 102.4%), as well as precise on the short- and long-term level (intra-day precision ≤2.1%), and shows an on-column detection limit of 0.2 ng and below. This, together with an excellent performance shown in the analysis of real samples, indicates that SFC is well suited for the fast and accurate determination of isoflavones in complex matrices. Disadvantages compared to the established approaches were not observed, so that SFC has to be considered in this case as an (at least) equivalent analytical alternative.

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. Micronutrient and protein-fortified whole grain puffed rice made by supercritical fluid extrusion.

    PubMed

    Paraman, Ilankovan; Wagner, Michael E; Rizvi, Syed S H

    2012-11-07

    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.

  17. 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.

  18. Probing Lewis Acid-Base Interactions with Born-Oppenheimer Molecular Dynamics: The Electronic Absorption Spectrum of p-Nitroaniline in Supercritical CO2.

    PubMed

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

    2015-07-02

    The structure and dynamics of p-nitroaniline (PNA) in supercritical CO2 (scCO2) at T = 315 K and ρ = 0.81 g cm(-3) are investigated by carrying out Born-Oppenheimer molecular dynamics, and the electronic absorption spectrum in scCO2 is determined by time dependent density functional theory. The structure of the PNA-scCO2 solution illustrates the role played by Lewis acid-base (LA-LB) interactions. In comparison with isolated PNA, the ν(N-O) symmetric and asymmetric stretching modes of PNA in scCO2 are red-shifted by -17 and -29 cm(-1), respectively. The maximum of the charge transfer (CT) absorption band of PNA in scSCO2 is at 3.9 eV, and the predicted red-shift of the π → π* electronic transition relative to the isolated gas-phase PNA molecule reproduces the experimental value of -0.35 eV. An analysis of the relationship between geometry distortions and excitation energies of PNA in scCO2 shows that the π → π* CT transition is very sensitive to changes of the N-O bond distance, strongly indicating a correlation between vibrational and electronic solvatochromism driven by LA-LB interactions. Despite the importance of LA-LB interactions to explain the solvation of PNA in scCO2, the red-shift of the CT band is mainly determined by electrostatic interactions.

  19. Enantioselective supercritical fluid chromatography using ristocetin A chiral stationary phases.

    PubMed

    Svensson, L A; Owens, P K

    2000-06-01

    Racemic mixtures of five acidic drugs have been successfully separated by supercritical fluid chromatography (SFC) using macrocyclic antibiotic chiral stationary phases (CSPs). A ristocetin A CSP has been prepared 'in-house' and effectively applied in packed capillary SFC to separate the enantiomers of dichlorprop (R(s) = 1.4), ketoprofen (R(s) = 0.9) and warfarin (R(s) = 0.9). The commercial ristocetin A CSP (Chirobiotic R) was subsequently studied in packed column SFC with similar results where the enantiomers of warfarin (R(s) = 2.2), coumachlor (R(s) = 2.5) and thalidomide (R(s) = 0.6) were separated. Interestingly, differences were observed between the two differently immobilised CSPs where the enantiomers of dichlorprop and ketoprofen, which were separated on the 'in-house' CSP, could not be separated on the commercial phase.

  20. Structural changes in supercritical fluids at high pressures

    NASA Astrophysics Data System (ADS)

    Santoro, Mario; Gorelli, Federico A.

    2008-06-01

    The structure of an archetypal model simple fluid system as argon has been investigated by x-ray diffraction at high pressures and room and high temperatures. Despite the markedly supercritical conditions (T=2 4Tc,P>102Pc) , the structure factor S(Q) is very similar, close to the melting line, to that observed in the liquid phase, thereby assessing a liquidlike structure with high atomic correlation, as proposed in a recent inelastic experiment. On the other hand, the S(Q) continuously changes upon approaching the extrapolation of the liquid-gas coexistence line in the (P/Pc,T/Tc) plane, ultimately exhibiting low atomic correlation, which reasonably indicates intermediate character between liquid and gas. The analysis of the S(Q) s based on the hard-sphere model shows that the changes are driven by the decrease in the packing fraction and the increase in the nearest-neighbor distance with decreasing pressure.

  1. 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.

  2. Comprehensive Review of Applicable Supercritical Fluid Extraction Research

    SciTech Connect

    Harvey, Scott; Wright, Cherylyn W.; Wright, Bob W.

    2001-09-10

    This comprehensive supercritical fluid extraction (SFE) literature review is divided into three major sections. The first section describes the electronic literature search details including the abstract service used and the different topics searched. This section also contains an overview of the seven search topics that yielded relevant references along with a brief synopsis of the most significant literature citations. These seven groupings are (1) chemical warfare agents; (2) explosives; (3) hazardous chemicals; (4) poisons, toxins and mycotoxins; (5) toxic (lethal) chemical and toxicants; (6) pesticides in soil; and (7) pesticides from plant and animal tissues. The second section contains tables of each of these groupings. Each of the seven tables contains entries for individual literature citations listed along with the specific compounds or compound classes that are addressed. The third section refers to the abstracts used in the literature search.

  3. Supercritical Fluid Extraction and Chromatography Using a Lee Scientific Series 600 SFE/SFC System

    DTIC Science & Technology

    1992-05-01

    Dioxide and Ethylene. Journal of Chemical Engineering Data , 26:47. Lee, M.L. and K.E. Markides 1987 Chromatography with Supercritical Fluids. Science...Publishers, Stoneham, MA. McHugh, M.A., and M.E. Paulaitis 1980 Solid Solubilities of Naphthalene and Biphenyle in Supercritical Carbon Dioxide. Journal of Chemical Engineering Data , 25

  4. SUPERCRITICAL FLUID EXTRACTION OF POLYCYCLIC AROMATIC HYDROCARBON MIXTURES FROM CONTAMINATED SOILS

    EPA Science Inventory

    Highly contaminated (with PAHs) topsoils were extracted with supercritical CO2 to determine the feasibility and mechanism of supercritical fluid extraction (SFE). Effect of SCF density, temperature, cosolvent type and amount, and of slurrying the soil with water were ...

  5. Leakage assessment and identification of fluid leakage scenarios at CO2 storage sites (Invited)

    NASA Astrophysics Data System (ADS)

    Bunz, S.

    2013-12-01

    One of the major objectives of the ECO2 project (EU FP7) is to assess the risks associated with the storage of CO2 below the seabed. Within this frame, work package (WP) 1 investigates the sedimentary cover at currently active and potential storage sites using novel geophysical baseline studies, monitoring and modeling techniques in order to better understand CO2 migration mechanisms and its spatial and temporal evolution. A proper risk assessment of CO2 storage hinges on a thorough understanding of the geological evolution of an area and a sound comprehension of subsurface anomalies associated with the flow of fluids and their governing geological controls. To this end, WP 1 has analyzed a wealth of seafloor imaging and seismic data from the industrial storage sites at Sleipner and Snøhvit on the Norwegian Margin. In addition to conventional seafloor and seismic data, several novel high-resolution acquisition technologies have been used during offshore expeditions in 2011 and 2012, and their data integrated into this study. A solid background on the geological development and the stratigraphic framework has been developed including an interpretation of subsurface structure and structures related to the presence of fluids and possible fluid pathways on the basis of conventional 3D seismic data and by integrating several additional high-resolution data sets. The data revealed a number of fluid-flow features, as for example gas chimneys, pipes, shallow gas accumulations, leaking faults, fractures along the seafloor as well as gas hydrates. Each of these structures or set of structures has been evaluated with respect to their occurrence, distribution, origin and as a means for providing a potential pathway for CO2 if it would leak out of the storage formation. On the basis of this evaluation and the assumptions that paleo fluid-flow structures may be reactivated by CO2 injection and that the caprock of the storage formation may breach, a number of potential leakage

  6. Supercritical carbon dioxide interpolymer complexes improve survival of B. longum Bb-46 in simulated gastrointestinal fluids.

    PubMed

    Thantsha, Mapitsi S; Cloete, Thomas E; Moolman, Francis S; Labuschagne, Philip W

    2009-01-31

    Gastric acidity is the main factor affecting viability of probiotics in the gastrointestinal tract (GIT). This study investigated the survival in simulated gastrointestinal fluids of Bifidobacterium longum Bb-46 encapsulated in interpolymer complexes formed in supercritical carbon dioxide (scCO(2)). Bacteria were exposed sequentially to simulated gastric fluid (SGF, pH 2) for 2 h and simulated intestinal fluid (SIF, pH 6.8) for 6 or 24 h. Total encapsulated bacteria were determined by suspending 1 g of product in SIF for 6 h at 37 degrees C prior to plating out. Plates were incubated anaerobically at 37 degrees C for 72 h. The interpolymer complex displayed pH-responsive release properties, with little to no release in SGF and substantial release in SIF. There was a limited reduction in viable counts at the end of exposure period due to encapsulation. Protection efficiency of the interpolymer complex was improved by addition of glyceryl monostearate (GMS). Gelatine capsules delayed release of bacteria from the interpolymer complex thus minimizing time of exposure to the detrimental conditions. Use of poly(caprolactone) (PCL), ethylene oxide-propylene oxide triblock copolymer (PEO-PPO-PEO) decreased the protection efficiency of the matrix. Interpolymer complex encapsulation showed potential for protection of probiotics and therefore for application in food and pharmaceuticals.

  7. Gas dynamics of heat-release-induced waves in supercritical fluids: revisiting the Piston Effect

    NASA Astrophysics Data System (ADS)

    Migliorino, Mario Tindaro; Scalo, Carlo

    2016-11-01

    We investigate a gasdynamic approach to the modeling of heat-release-induced compression waves in supercritical fluids. We rely on highly resolved one-dimensional fully compressible Navier-Stokes simulations of CO2 at pseudo-boiling conditions in a closed duct inspired by the experiments of Miura et al.. Near-critical fluids exhibit anomalous variations of thermodynamic variables taken into account by adopting the Peng-Robinson equation of state and Chung's Method. An idealized heat source is applied, away from the boundaries, resulting in the generation of compression waves followed by contact discontinuities bounding a region of hot expanding fluid. For higher heat-release rates such compressions are coalescent with distinct shock-like features (i.e. non-isentropicity and propagation Mach numbers measurably greater than unity) and a non-uniform post-shock state, not present in ideal gas simulations, caused by the highly nonlinear equation of state. Thermoacoustic effects are limited to: (1) a one-way/one-time thermal-to-acoustic energy conversion, and (2) cumulative non-isentropic bulk heating due to the resonating compression waves, resulting in what is commonly referred to as the Piston Effect.

  8. Nanoscale engineering materials by supercritical fluid and atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Peng, Qing

    With the development of material science and technology, modification of substrates, which have random geometry and high aspect ratio three dimensional (3D) complex structures, with desired functional, reactive and stable coatings becomes important and challenging. The ability to fabricate mono- or multi-layers of functional materials with precisely controlled dimensions, finely tuned composition and molecular structures, attracts significant interests in materials science and is the key to construct such devices and structures at nano- and micro-scale with desired properties. In this study, supercritical carbon dioxide (scCO2) has been studied as an alternative route for modifying substrates due to the unique gas-like (low viscosity, high diffusivity and zero surface tension) and liquid-like properties (high density). (1) The reaction kinetics of metal oxides thin film deposition from pyrolysis of metal organics in scCO2 was studied in detail. This method was demonstrated as a powerful technique to coat oxides, including Al2O3, Ga2O3 and others, into 3D high aspect ratio complex structure of carbon nanotubes (CNTs) forest. (2) The low temperature scCO 2 based hydrogenolysis process was developed as a useful way to functionalize aligned CNTs forest with dense Nickel nanoparticles. On the second part of this work, atomic layer deposition (ALD)/molecular layer deposition (MLD), as a vapor phase, stepwise and self-limiting vacuum based deposition process, was demonstrated as a powerful way to form highly conformal and uniform film onto substrates, even into highly complex 3D complex structures. In this study, (4) Metal oxide ALD is applied onto 3D electrospun polymer microfiber mats template to illustrate an effective and robust strategy to fabricate long and uniform metal oxide microtubes with precisely controllable wall thickness. Designer tubes of various sizes and different materials were demonstrated by using this method. (5) By further extending this technique

  9. Determination of arsenic species in solid matrices utilizing supercritical fluid extraction coupled with gas chromatography after derivatization with thioglycolic acid n-butyl ester.

    PubMed

    Wang, Zhifeng; Cui, Zhaojie

    2016-12-01

    A method using derivatization and supercritical fluid extraction coupled with gas chromatography was developed for the analysis of dimethylarsinate, monomethylarsonate and inorganic arsenic simultaneously in solid matrices. Thioglycolic acid n-butyl ester was used as a novel derivatizing reagent. A systematic discussion was made to investigate the effects of pressure, temperature, flow rate of the supercritical CO2 , extraction time, concentration of the modifier, and microemulsion on extraction efficiency. The application for real environmental samples was also studied. Results showed that thioglycolic acid n-butyl ester was an effective derivatizing reagent that could be applied for arsenic speciation. Using methanol as modifier of the supercritical CO2 can raise the extraction efficiency, which can be further enhanced by adding a microemulsion that contains Triton X-405. The optimum extraction conditions were: 25 MPa, 90°C, static extraction for 10 min, dynamic extraction for 25 min with a flow rate of 2.0 mL/min of supercritical CO2 modified by 5% v/v methanol and microemulsion. The detection limits of dimethylarsinate, monomethylarsonate, and inorganic arsenic in solid matrices were 0.12, 0.26, and 1.1 mg/kg, respectively. The optimized method was sensitive, convenient, and reliable for the extraction and analysis of different arsenic species in solid samples.

  10. Numerical studies of fluid-rock interactions in EnhancedGeothermal Systems (EGS) with CO2 as working fluid

    SciTech Connect

    Xu, Tianfu; Pruess, Karsten; Apps, John

    2008-01-17

    There is growing interest in the novel concept of operating Enhanced Geothermal Systems (EGS) with CO{sub 2} instead of water as heat transmission fluid. Initial studies have suggested that CO{sub 2} will achieve larger rates of heat extraction, and can offer geologic storage of carbon as an ancillary benefit. Fluid-rock interactions in EGS operated with CO{sub 2} are expected to be vastly different in zones with an aqueous phase present, as compared to the central reservoir zone with anhydrous supercritical CO{sub 2}. Our numerical simulations of chemically reactive transport show a combination of mineral dissolution and precipitation effects in the peripheral zone of the systems. These could impact reservoir growth and longevity, with important ramifications for sustaining energy recovery, for estimating CO{sub 2} loss rates, and for figuring tradeoffs between power generation and geologic storage of CO{sub 2}.

  11. Low temperature extraction and upgrading of oil sands and bitumen in supercritical fluid mixtures.

    PubMed

    Brough, Sarah A; Riley, Sandra H; McGrady, G Sean; Tanhawiriyakul, Supaporn; Romero-Zerón, Laura; Willson, Christopher D

    2010-07-21

    Preliminary results are reported for the extraction and catalytic hydrocracking of Alberta bitumen and oil sands using supercritical fluid mixtures; high levels of extraction and upgrading were attained using reaction conditions significantly milder than those previously reported.

  12. Supercritical fluid extraction of sulphamethazine and its metabolites from meat tissues.

    PubMed

    Din, N; Bartle, K D; Clifford, A A; McCormack, A; Castle, L

    1997-01-01

    An investigation is reported of factors affecting the supercritical fluid extraction of sulphamethazine and five of its metabolites from spiked meat (swine liver and kidney). The addition of the polar modifier methanol to the carbon dioxide extracting fluid was found to generally enhance recoveries under subcritical and supercritical conditions. Recoveries of the ionic metabolites were increased by up to 72% when employing tetramethylammonium hydroxide for ion pairing in situ with the supercritical fluid extraction. Extraction efficiency is demonstrated to be dependent on the matrix. Extractions of the less polar compounds from the kidney are more successful than from the liver, which corresponds to their partitioning into the supercritical fluid and/or the greater fraction of highly extractable fatty materials. The kidney was more retentive than liver for the relatively more polar compounds, which suggests that the liver offers a less polar environment under the same extraction conditions.

  13. Metal Carbonation of Forsterite in Wet Supercritical CO2: The Role of H2O Studied by Solid State C-13 and Si-29 NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hu, J.; Kwak, J.; Turcu, R. V.; Rosso, K. M.; Ilton, E. S.; Wang, C.; Sears, J. A.; Felmy, A. R.; Hoyt, D. W.

    2010-12-01

    Selected as a model mineral carbonation system for geological carbon sequestration in mafic host rocks, chemical mechanisms of forsterite carbonation in supercritical CO2 containing water varied from dry to well above saturation, including at saturation, were investigated by a combination of solid state NMR (C-13 SP-, CP-MAS, Si-29 SP-, CP-MAS), XRD, TEM and XPS. Run conditions were 80 degrees (C) and 75 bars. Major findings are as follows. At high water contents where a bulk aqueous solution coexisted with water-saturated scCO2, forsterite was converted into magnesite and a separate Mg-free amorphous SiO2 reaction product characterized by highly polymerized oligomeric Q4, and to a lesser extent by Q3 silica species. As the amount of added water was reduced, hydrated intermediate reaction products that did not evolve to magnesite could be identified until at zero water no reaction intermediates or magnesite carbonation products were observed. The intermediate reaction products identified were a complex mixture of partially hydrated/hydroxylated magnesium carbonate species and a variety of surface silica species with low polymerization extent. The intermediates were mainly in an amorphous state, forming a thin layer on the surface. Formation of these intermediate species consumes water by hydrolysis of Mg-O-Si linkages at the forsterite surface as well as by incorporation of water in the lattice. If insufficient water is available, the reaction is found not to proceed far enough to form magnesite and amorphous SiO2. Water in excess of this limit appears necessary for the intermediates to evolve to anhydrous magnesite, a process that is expected to liberate water for continued reaction. Hence, for a given fluid/forsterite ratio there appears to be a water threshold (i.e., the formation of H2O film with sufficient thickness estimated to be between 3.2 and 18.4 nm) above which a significant portion of the water is recycled in an apparent quasi-catalytic role for the

  14. Integral equations for the microstructures of supercritical fluids

    SciTech Connect

    Lee, L.L.; Cochran, H.D.

    1993-11-01

    Molecular interactions and molecular distributions are at the heart of the supercritical behavior of fluid mixtures. The distributions, i.e. structure, can be obtained through any of the three routes: (1) scattering experiments, (2) Monte Carlo or molecular dynamics simulation, and (3) integral equations that govern the relation between the molecular interactions u(r) and the probability distributions g{sub ij}(r). Most integral equations are based on the Ornstein-Zernike relation connecting the total correlation to the direct correlation. The OZ relation requires a {open_quotes}closure{close_quotes} equation to be solvable. Thus the Percus-Yevick, hypernetted chain, and mean spherical approximations have been proposed. The authors outline the numerical methods of solution for these integral equations, including the Picard, Labik-Gillan, and Baxter methods. Solution of these equations yields the solvent-solute, solvent-solvent, and solute-solute pair correlation functions (pcf`s). Interestingly, these pcf`s exhibit characteristical signatures for supercritical mixtures that are classified as {open_quotes}attractive{close_quotes} or {open_quotes}repulsive{close_quotes} in nature. Close to the critical locus, the pcf shows enhanced first neighbor peaks with concomitant long-range build-ups (sic attractive behavior) or reduced first peaks plus long-range depletion (sic repulsive behavior) of neighbors. For ternary mixtures with entrainers, there are synergistic effects between solvent and cosolvent, or solute and cosolute. These are also detectable on the distribution function level. The thermodynamic consequences are deciphered through the Kirkwood-Buff fluctuation integrals (G{sub ij}) and their matrix inverses: the direct correlation function integrals (DCFI`s). These quantities connect the correlation functions to the chemical potential derivatives (macroscopic variables) thus acting as {open_quotes}bridges{close_quotes} between the two Weltanschauungen.

  15. A new reference method for the determination of the total CO2 concentration in biological fluids.

    PubMed

    Dijkhuizen, P; Fongers, T M; Rispens, P; Zijlstra, W G

    1978-06-15

    It appeared that a part of a measuring system recently developed for the determination of the oxygen content of blood (Dijkhuizen, P., Kwant, G. and Zijlstra, W.G. (1976) Clin. Chim. Acta 68, 79), was perfectly suitable for measuring the total CO2 content of blood, plasma or other fluids. CO2-free room air is pumped through an extraction vessel in which all the CO2 of the sample is set free by an acid reagent, and swept by the carrier gas to a titration vessel containing a BaCl2 solution. CO2 is bound as BaCO3 and the ensuing H+ titrated with an NaOH solution. The method was tested by measuring a series of Na2CO3 reference solutions. The values measured by titration amounted to 99.4 +/- 0.8% of the concentration of the reference solutions (range 10--50 mmol 1(-1). The coefficient of variation was 1.8% for 5 mmol 1(-1) solutions and 0.2% for 50 mmol 1(-1) solutions. In measuring a series of 60 blood samples the coefficient of variation as calculated from duplicate determinations was 1%.

  16. Supercritical fluid extraction of particulate and adsorbent materials. Report for February 1984-January 1985

    SciTech Connect

    Wright, B.W.; Smith, R.D.

    1986-03-01

    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 show that supercritical fluids are effective extractants for many SVOCs, and are often competitive with conventional Soxhlet extraction. Advantages of SCFs over conventional methods include higher extraction efficiency, more rapid extraction, and reduced decomposition of thermally labile compounds.

  17. Analysis of semi-volatile organic compounds using supercritical fluid methodologies

    SciTech Connect

    Wright, B.W.; Chess, E.K.; Yonker, C.R.; Smith, R.D.

    1985-06-01

    This study demonstrates the applicability of supercritical fluid chromatography (SFC) and analytical supercritical fluid extraction (SFE) for the analysis of semi-volatile compounds. Mixtures of nitro-polycyclic aromatic hydrocarbons that are not ammenable to gas chromatography were separated using SFC with tentative compound identifications made by SFC-MS. Comparisons of analytical SFE of XAD-2 resin and NBS Urban Dust (SRM 1649) to conventional Soxhlet extraction are also discussed.

  18. Precipitation of microsize organic particles from supercritical fluids

    SciTech Connect

    Chang, C.J.; Randolph, A.D. )

    1989-11-01

    The precipitation of organic particles from supercritical fluids (SF) by expansion (SFX) has become an interesting alternative to milling without thermal decomposition. The authors report how through the rapid expansion process, a dramatic change of the solute supersaturation ratio was created causing subsequent precipitation with a narrow particle-size distribution. It was found that {beta}-carotene precipitates from SF ethylene and ethane have the feed material crystallinity. However, SF CO{sub 2} reacted with {beta}-carotene and did not give characteristic {beta}-carotene X-ray spectra. The mean particle sizes of these precipitates were in the submicron range (ca 0.3 {mu}m). Increased solubility was obtained by addition of toluene as cosolvent in SF ethylene. It was found that the mean size of {beta}-carotene particles, generally remained unchanged if the toluene concentration was less than 1 1/2 mol %. The SFX process appears to be in a single fluid phase when up to 1 1/2 mol % toluene cosolvent is used.