Graphite-supported platinum catalysts: Effects of gas and aqueous phase treatments

Energy Technology Data Exchange (ETDEWEB)

Vleeming, J.H.; Kuster, B.F.M.; Marin, G.B. [Eindhoven Univ. of Technology (Netherlands)] [and others

1997-03-01

The effects on the platinum particle diameter and the available platinum surface area of a graphite-supported platinum catalyst resulting from pretreatments and from performing a selective oxidation reaction are investigated. In the gas phase considerable catalyst sintering occurs only in the presence of oxygen at 773 K due to extensive carbon burn-off, whereas in an aqueous phase platinum particle growth is limited upon oxidative treatment. A hydrogen treatment in aqueous phase at 363 K causes platinum particle growth, aggregate formation, and covering of metal sites. These phenomena become more important with increasing pH. Platinum particle growth and aggregate formation are attributed to platinum particle rather than platinum adatom mobility and is caused by the destruction of the oxygen-containing surface groups on the graphite support, which serve as anchorage sites for the platinum particles. Site covering is caused by products originating from the graphite support, which are formed as a result of the reductive treatments. When performing the aqueous phase oxidation of methyl {alpha}-D-glucopyranoside at 323 K and a pH of 9, catalyst modifications are small under oxidative conditions. Exposure of the catalyst for several hours to methyl {alpha}-D-glucopyranoside under the same conditions but in the absence of oxygen causes site covering. 50 refs., 9 figs., 1 tab.

Synergistic extraction of transition metal cations from aqueous media by two separated organic phases

International Nuclear Information System (INIS)

Goldberg, I.

1991-12-01

We have therefore initiated novel approaches to the study of the mechanism of the synergistic extraction of metal ions by means of two separated organic phases, which are brought in contact with the same aqueous phase. The present work is concerned with the extraction of transition metals and actinides ions from nitric acid by chelating agents e.g., HTTA thenoyltrifluoroacetone in a diluent - the first organic phase, and by natural donor, e.g., TBP, tri-butyl phosphate in a diluent the second organic phase. The adduct formation was studied by means of spectrochemical and radiochemical methods. In the first approach the aqueous phase was attacked with both organic phases simultanously (the static or parallel extraction). In this method organic phase are separated one from the other. It was shown that even in the absence of mixing, synergism is observed under this experimental conditions. The results indicate, that adduct formation occurs in both organic phases. Nevertheless the enhanchment of extraction in the TBP phase is by far greater than that in the HTTA containing phase. This approach has one disadvatage, viz., the experiments are very time consuming, a typical experiment requiring over 10 days. In order to overcome this difficulty, the following experiments were carried out: the aqueous phase were first shaken with diluent containing an anionic ligand and the phases were allowed to separate. Then the aqueous solution were shaken with diluent containing a netural donor and the phase again were allowed to separate. The concentration of the metal ions in all the phases were determined. The experiments were repeated with an other diluent replacing the first diluent in one or both organic phases. In this way eight sequences of experiments were carried out for each concentration set chosen. The results thus point out that this experimental approach open new possibilities to investigate the mechanism and the kinetics of synergistic extraction processes. (author) the

Continuous-flow ultrasound assisted oxidative desulfurization (UAOD) process: An efficient diesel treatment by injection of the aqueous phase.

Science.gov (United States)

Rahimi, Masoud; Shahhosseini, Shahrokh; Movahedirad, Salman

2017-11-01

A new continuous-flow ultrasound assisted oxidative desulfurization (UAOD) process was developed in order to decrease energy and aqueous phase consumption. In this process the aqueous phase is injected below the horn tip leading to enhanced mixing of the phases. Diesel fuel as the oil phase with sulfur content of 1550ppmw and an appropriate mixture of hydrogen peroxide and formic acid as the aqueous phase were used. At the first step, the optimized condition for the sulfur removal has been obtained in the batch mode operation. Hence, the effect of more important oxidation parameters; oxidant-to-sulfur molar ratio, acid-to-sulfur molar ratio and sonication time were investigated. Then the optimized conditions were obtained using Response Surface Methodology (RSM) technique. Afterwards, some experiments corresponding to the best batch condition and also with objective of minimizing the residence time and aqueous phase to fuel volume ratio have been conducted in a newly designed double-compartment reactor with injection of the aqueous phase to evaluate the process in a continuous flow operation. In addition, the effect of nozzle diameter has been examined. Significant improvement on the sulfur removal was observed specially in lower sonication time in the case of dispersion method in comparison with the conventional contact between two phases. Ultimately, the flow pattern induced by ultrasonic device, and also injection of the aqueous phase were analyzed quantitatively and qualitatively by capturing the sequential images. Copyright © 2017 Elsevier B.V. All rights reserved.

Extraction of Oxytetracycline Hydrochloride in Aqueous Two-phase System of Acetone and Ammonium Sulfate

International Nuclear Information System (INIS)

Han, J.

2013-01-01

Summary: Aqueous two-phase system (ATPS) is an efficient implement for separation of various substrates, and extracted by an aqueous two-phase system has been successful ly applied in the downstream processing of various biological compounds. In this research, the extraction of oxytetracycline hydrochloride (OTC-HCl) was carried out in an aqueous two-phase system containing acetone and ammonium sulfate solution, which partitioned the antibiotic to the upper phase. The effects of some parameters on the extraction efficiency of OTC-HCl were studied in detail, including temperature, the volume of acetone, the pH value of ammonium sulfate solution, the concentrations of (NH/sub 4/)/sub 2/ SO/sub 4/ and OTC-HCl. The results showed that the volume of acetone, the pH value of ammonium sulfate solution and the concentration of OTC-HCl in feed had significant effects on the extraction efficiency of OTC-HCl, but the effects of temperature on the extraction of OTC-HCl was not obvious. (author)

Extraction of Oxytetracycline Hydrochloride in Aqueous Two-phase System of Acetone and Ammonium Sulfate

Energy Technology Data Exchange (ETDEWEB)

Han, J. [Jiangsu Univ., Zhenjiang (China). Dept. of Food and Biological Engineering

2013-02-15

Summary: Aqueous two-phase system (ATPS) is an efficient implement for separation of various substrates, and extracted by an aqueous two-phase system has been successful ly applied in the downstream processing of various biological compounds. In this research, the extraction of oxytetracycline hydrochloride (OTC-HCl) was carried out in an aqueous two-phase system containing acetone and ammonium sulfate solution, which partitioned the antibiotic to the upper phase. The effects of some parameters on the extraction efficiency of OTC-HCl were studied in detail, including temperature, the volume of acetone, the pH value of ammonium sulfate solution, the concentrations of (NH/sub 4/)/sub 2/ SO/sub 4/ and OTC-HCl. The results showed that the volume of acetone, the pH value of ammonium sulfate solution and the concentration of OTC-HCl in feed had significant effects on the extraction efficiency of OTC-HCl, but the effects of temperature on the extraction of OTC-HCl was not obvious. (author)

Subcritical hydrothermal liquefaction of barley straw in fresh water and recycled aqueous phase

DEFF Research Database (Denmark)

Zhu, Zhe; Toor, Saqib; Rosendahl, Lasse

2014-01-01

This project focuses on the investigation of addition of aqueous phase in the production of biofuel from biomass through hydrothermal liquefaction (HTL) technology. Hydrothermal liquefaction is a wet thermal conversion process, which can convert all kinds of biomass to fuels. In this study, barley...... straw was first liquefied in fresh distilled water with the presence of K2CO3 catalyst at 300 C as the reference run. Afterwards, the aqueous phase which is obtained from liquefaction process in the previous run was recycled and used as the reaction medium from the second to the fourth run....... With the addition of recycling aqueous phase in HTL process, it is expected that the amount of the waste water and energy consumption can be reduced. The effect of water recirculation on product yield and properties was investigated in this study. The results showed that bio-oil yield was 34.85 wt% when the barley...

Development of linear free energy relationships for aqueous phase radical-involved chemical reactions.

Science.gov (United States)

Minakata, Daisuke; Mezyk, Stephen P; Jones, Jace W; Daws, Brittany R; Crittenden, John C

2014-12-02

Aqueous phase advanced oxidation processes (AOPs) produce hydroxyl radicals (HO•) which can completely oxidize electron rich organic compounds. The proper design and operation of AOPs require that we predict the formation and fate of the byproducts and their associated toxicity. Accordingly, there is a need to develop a first-principles kinetic model that can predict the dominant reaction pathways that potentially produce toxic byproducts. We have published some of our efforts on predicting the elementary reaction pathways and the HO• rate constants. Here we develop linear free energy relationships (LFERs) that predict the rate constants for aqueous phase radical reactions. The LFERs relate experimentally obtained kinetic rate constants to quantum mechanically calculated aqueous phase free energies of activation. The LFERs have been applied to 101 reactions, including (1) HO• addition to 15 aromatic compounds; (2) addition of molecular oxygen to 65 carbon-centered aliphatic and cyclohexadienyl radicals; (3) disproportionation of 10 peroxyl radicals, and (4) unimolecular decay of nine peroxyl radicals. The LFERs correlations predict the rate constants within a factor of 2 from the experimental values for HO• reactions and molecular oxygen addition, and a factor of 5 for peroxyl radical reactions. The LFERs and the elementary reaction pathways will enable us to predict the formation and initial fate of the byproducts in AOPs. Furthermore, our methodology can be applied to other environmental processes in which aqueous phase radical-involved reactions occur.

Explicit modeling of volatile organic compounds partitioning in the atmospheric aqueous phase

Directory of Open Access Journals (Sweden)

C. Mouchel-Vallon

2013-01-01

Full Text Available The gas phase oxidation of organic species is a multigenerational process involving a large number of secondary compounds. Most secondary organic species are water-soluble multifunctional oxygenated molecules. The fully explicit chemical mechanism GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere is used to describe the oxidation of organics in the gas phase and their mass transfer to the aqueous phase. The oxidation of three hydrocarbons of atmospheric interest (isoprene, octane and α-pinene is investigated for various NO_x conditions. The simulated oxidative trajectories are examined in a new two dimensional space defined by the mean oxidation state and the solubility. The amount of dissolved organic matter was found to be very low (yield less than 2% on carbon atom basis under a water content typical of deliquescent aerosols. For cloud water content, 50% (isoprene oxidation to 70% (octane oxidation of the carbon atoms are found in the aqueous phase after the removal of the parent hydrocarbons for low NO_x conditions. For high NO_x conditions, this ratio is only 5% in the isoprene oxidation case, but remains large for α-pinene and octane oxidation cases (40% and 60%, respectively. Although the model does not yet include chemical reactions in the aqueous phase, much of this dissolved organic matter should be processed in cloud drops and modify both oxidation rates and the speciation of organic species.

Extraction of peptide tagged cutinase in detergent-based aqueous two-phase systems

NARCIS (Netherlands)

Rodenbrock, A.; Selber, K.; Egmond, M.R.; Kula, M.-R.

2010-01-01

Detergent-based aqueous two-phase systems have the advantage to require only one auxiliary chemical to induce phase separation above the cloud point. In a systematic study the efficiency of tryptophan-rich peptide tags was investigated to enhance the partitioning of an enzyme to the detergent-rich

Toward stable nickel catalysts for aqueous phase reforming of biomass-derived feedstock under reducing and alkaline conditions

NARCIS (Netherlands)

Haasterecht, van T.; Ludding, C.C.I.; Jong, de K.P.; Bitter, J.H.

2014-01-01

Nickel nanoparticles supported on carbon nanofibers (CNF) can be stabilized in aqueous phase processes at elevated temperatures and pressures by tuning the reaction conditions to control Ni oxidation and leaching. As a showcase, Ni/CNF was used for the production of hydrogen via aqueous phase

Compact and highly stable quantum dots through optimized aqueous phase transfer

Science.gov (United States)

Tamang, Sudarsan; Beaune, Grégory; Poillot, Cathy; De Waard, Michel; Texier-Nogues, Isabelle; Reiss, Peter

2011-03-01

A large number of different approaches for the aqueous phase transfer of quantum dots have been proposed. Surface ligand exchange with small hydrophilic thiols, such as L-cysteine, yields the lowest particle hydrodynamic diameter. However, cysteine is prone to dimer formation, which limits colloidal stability. We demonstrate that precise pH control during aqueous phase transfer dramatically increases the colloidal stability of InP/ZnS quantum dots. Various bifunctional thiols have been applied. The formation of disulfides, strongly diminishing the fluorescence QY has been prevented through addition of appropriate reducing agents. Bright InP/ZnS quantum dots with a hydrodynamic diameter <10 nm and long-term stability have been obtained. Finally we present in vitro studies of the quantum dots functionalized with the cell-penetrating peptide maurocalcine.

Kinetics, Mechanism, and Secondary Organic Aerosol Yield of Aqueous Phase Photo-oxidation of α-Pinene Oxidation Products.

Science.gov (United States)

Aljawhary, Dana; Zhao, Ran; Lee, Alex K Y; Wang, Chen; Abbatt, Jonathan P D

2016-03-10

Formation of secondary organic aerosol (SOA) involves atmospheric oxidation of volatile organic compounds (VOCs), the majority of which are emitted from biogenic sources. Oxidation can occur not only in the gas-phase but also in atmospheric aqueous phases such as cloudwater and aerosol liquid water. This study explores for the first time the aqueous-phase OH oxidation chemistry of oxidation products of α-pinene, a major biogenic VOC species emitted to the atmosphere. The kinetics, reaction mechanisms, and formation of SOA compounds in the aqueous phase of two model compounds, cis-pinonic acid (PIN) and tricarballylic acid (TCA), were investigated in the laboratory; TCA was used as a surrogate for 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a known α-pinene oxidation product. Aerosol time-of-flight chemical ionization mass spectrometry (Aerosol-ToF-CIMS) was used to follow the kinetics and reaction mechanisms at the molecular level. Room-temperature second-order rate constants of PIN and TCA were determined to be 3.3 (± 0.5) × 10(9) and 3.1 (± 0.2) × 10(8) M(-1) s(-1), respectively, from which were estimated their condensed-phase atmospheric lifetimes. Aerosol-ToF-CIMS detected a large number of products leading to detailed reaction mechanisms for PIN and MBTCA. By monitoring the particle size distribution after drying, the amount of SOA material remaining in the particle phase was determined. An aqueous SOA yield of 40 to 60% was determined for PIN OH oxidation. Although recent laboratory studies have focused primarily on aqueous-phase processing of isoprene-related compounds, we demonstrate that aqueous formation of SOA materials also occurs from monoterpene oxidation products, thus representing an additional source of biogenically driven aerosol formation.

Different Diversity and Distribution of Archaeal Community in the Aqueous and Oil Phases of Production Fluid From High-Temperature Petroleum Reservoirs

Directory of Open Access Journals (Sweden)

Bo Liang

2018-04-01

Full Text Available To get a better knowledge on how archaeal communities differ between the oil and aqueous phases and whether environmental factors promote substantial differences on microbial distributions among production wells, we analyzed archaeal communities in oil and aqueous phases from four high-temperature petroleum reservoirs (55–65°C by using 16S rRNA gene based 454 pyrosequencing. Obvious dissimilarity of the archaeal composition between aqueous and oil phases in each independent production wells was observed, especially in production wells with higher water cut, and diversity in the oil phase was much higher than that in the corresponding aqueous phase. Statistical analysis further showed that archaeal communities in oil phases from different petroleum reservoirs tended to be more similar, but those in aqueous phases were the opposite. In the high-temperature ecosystems, temperature as an environmental factor could have significantly affected archaeal distribution, and archaeal diversity raised with the increase of temperature (p < 0.05. Our results suggest that to get a comprehensive understanding of petroleum reservoirs microbial information both in aqueous and oil phases should be taken into consideration. The microscopic habitats of oil phase, technically the dispersed minuscule water droplets in the oil could be a better habitat that containing the indigenous microorganisms.

Aqueous preparation of polyethylene glycol/sulfonated graphene phase change composite with enhanced thermal performance

International Nuclear Information System (INIS)

Li, Hairong; Jiang, Ming; Li, Qi; Li, Denian; Chen, Zongyi; Hu, Waping; Huang, Jing; Xu, Xizhe; Dong, Lijie; Xie, Haian; Xiong, Chuanxi

2013-01-01

Highlights: • We report an aqueous preparation technique of PEG/graphene phase change composite. • Hydrophilic sulfonated graphene (SG) nanosheets were synthesized. • Large increase in thermal conductivity is attained at low SG loading. • High latent heat is retained due to the low filler loading. • Affinity between SG and PEG contributes to the enhanced thermal performance. - Abstract: A polyethylene glycol (PEG)/sulfonated graphene (SG) phase change composite with enhanced thermal performance was prepared by solution processing in aqueous medium. It is remarkable that the addition of only 4 wt.% of SG to PEG could lead to a four times higher increase in thermal conductivity and a slight decrease in the phase change enthalpy, which is attributed to the formation of efficient thermal conductive network within the PEG matrix relevant to the excellent thermal property and unique 2-dimensional morphology of graphene as well as strong interface affinity between PEG matrix and SG nanosheets. The aqueous preparation technique is expected to pioneer a new way to prepare environment friendly organic phase change materials, and the production of PEG/SG composites is potentially scalable due to the facile fabricating process

Bioligand-mediated partitioning of radionuclides to the aqueous phase

International Nuclear Information System (INIS)

Johnsson, A.; Pedersen, K.; Oedegaard-Jensen, A.; Jakobsson, A.M.; Ekberg, C.

2008-01-01

The aqueous-phase partitioning of 59 Fe, 147 Pm, 234 Th and 241 Am by complexing compounds from subsurface bacteria has previously been studied in the presence of quartz sand. In this study the aqueous-phase partitioning of pico- to submicromolar amounts of 59 Fe, 147 Pm, 234 Th and 241 Am was analyzed in the presence of TiO 2 and exudates from three species of subsurface bacteria: Pseudomonas fluorescens, Pseudomonas stutzeri, and Shewanella putrefaciens. All were grown under aerobic conditions and P. stutzeri and S. putrefaciens were grown under anaerobic conditions as well. The supernatants of the aerobic and anaerobic cultures were collected and radionuclide was added. TiO 2 , with BET surface area of 49.9 m 2 x g -1 , was added to the supernatant radionuclide mix, and the pH was adjusted to approximately 8. After incubation, the amount of radionuclide in the liquid phase of the samples and controls was analyzed using scintillation method. Two types of values were calculated: solution% = the activity maintained in solution relative to the total activity, and Q-values = the quotient between the activity in samples and the activity in controls. Aerobic supernatants had solution% values between 89% and 100% for 59 Fe and between 18 and 43% for 234 Th. The solution% values for 241 Am and 147 Pm were less than 2% overall, but the Q-values were between 34 and 115 times more 241 Am in bacterial supernatants than in controls. The corresponding values for 147 Pm ranged from 6 to 20 times more than in the control. The solution% values for all elements in the presence of anaerobic supernatants were below 2%, but the Q-values clustered around 7 for 59 Fe and ranging from 2 to 29 for 234 Th, indicated that anaerobic supernatants partitioned these elements to the aqueous phase. Both aerobic and anaerobic supernatants tested positive for complexing compounds when analyzed, using the Chrome Azurol S assay. Complexation with excreted organic ligands is most likely the reason

Peptide-tagged proteins in aqueous two-phase systems

OpenAIRE

Nilsson, Anna

2002-01-01

This thesis deals with proteins containing peptide tags for improved partitioning in aqueous two-phase systems. Qualitatively the peptide-tagged protein partitioning could be predicted from peptide data, i.e. partitioning trends found for peptides were also found for the peptide-tagged proteins. However, full effect of the tag as expected from peptide partitioning was not found in the tagged protein. When alkyl-ethylene oxide surfactant was included in a two-polymer system, almost full effect...

Dissolved organic carbon enhances the mass transfer of hydrophobic organic compounds from Nonaqueous Phase Liquids (NAPLs) into the aqueous phase

NARCIS (Netherlands)

Smith, K.E.C.; Thullner, M.; Wick, L.Y.; Harms, H.

2011-01-01

The hypothesis that dissolved organic carbon (DOC) enhances the mass transfer of hydrophobic organic compounds from nonaqueous phase liquids (NAPLs) into the aqueous phase above that attributable to dissolved molecular diffusion alone was tested. In controlled experiments, mass transfer rates of

Analysis of continuous fermentation processes in aqueous two-phase systems

Energy Technology Data Exchange (ETDEWEB)

Jarzebski, A B; Malinowski, J J [Polish Academy of Sciences, Gliwice (Poland). Inst. of Chemical Engineering; Goma, G; Soucaille, P [INSA, 31 - Toulouse (France). Dept. de Genie Biochimique et Alimentaire

1992-05-01

Simulations of continuous ethanol or acetonobutylic fermentations in aqueous two-phase systems show that at high substrate feed concentrations it is possible to obtain solvent productivities about 25-40% higher than in conventional systems with cell recycle if the biomass bleed rate is kept about one tenth of the value of D. (orig.).

Quantification and speciation of volatile fatty acids in the aqueous phase.

Science.gov (United States)

Lee, Jechan; Kim, Jieun; Oh, Jeong-Ik; Lee, Sang-Ryong; Kwon, Eilhann E

2017-11-01

This study lays great emphasis on establishing a reliable analytical platform to quantify and specify volatile fatty acids (VFAs) in the aqueous phase by derivatizing VFAs into their corresponding alkyl esters via thermally-induced rapid esterification (only 10 s reaction time). To this end, reaction conditions for the thermally-induced rapid esterification are optimized. A volumetric ratio of 0.5 at 400 °C for VFA/methanol is identified as the optimal reaction conditions to give ∼90% volatile fatty acid methyl ester (VFAME) yield. To maintain a high yield of VFAMEs, this study suggests that dilution of the sample to an optimum concentration (∼500 ppm for each VFA) is required. Derivatization of VFAs into VFAMEs via the thermally-induced rapid esterification is more reliable to quantify and specify VFAs in the aqueous phase than conventional colorimetric method. Copyright © 2017 Elsevier Ltd. All rights reserved.

Theoretical Investigation of the Structural Stabilities of Ceria Surfaces and Supported Metal Nanocluster in Vapor and Aqueous Phases

Energy Technology Data Exchange (ETDEWEB)

Ren, Zhibo [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Liu, Ning [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Chen, Biaohua [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Li, Jianwei [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Mei, Donghai [Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, United States

2018-01-25

Understanding the structural stability and dynamics at the interface between the solid metal oxide and aqueous phase is significant in a variety of industrial applications including heterogeneous catalysis and environmental remediation. In the present work, the stabilities of three low-index ceria (CeO2) surfaces, i.e., (111), (110) and (100) in vapor and aqueous phases were studied using ab initio molecular dynamics simulations and density functional theory (DFT) calculations. Gibbs surface free energies as a function of temperature, water partial pressure, and water coverages were calculated using DFT based atomistic thermodynamic approach. On the basis of surface free energies, the morphology and exposed surface structures of the CeO2 nanoparticle were predicted using Wulff construction principle. It is found that the partially hydroxylated (111) and (100) are two major surface structures of CeO2 nanoparticles in vapor phase at ambient temperature (300 K). As the temperature increases, the fully dehydrated (111) surface gradually becomes the most dominant surface structure. While in aqueous phase, the exposed surface of the CeO2 nanoparticle is dominated by the hydroxylated (110) structure at 393 K. Finally, the morphology and stability of a cuboctahedron Pt13 nanocluster supported on CeO2 surfaces in both gas and aqueous phases were investigated. In gas phase, the supported Pt13 nanocluster has the tendency to wetting the CeO2 surface due to the strong metal-support interaction. The calculated interaction energies suggest the CeO2(110) surface provides the best stability for the Pt13 nanocluster. The CeO2 supported Pt13 nanoclusters are oxidized. Compared to the gas phase, the morphology of the CeO2 supported Pt13 nanocluster is less distorted due to the solvation effect provided by surrounding water molecules in aqueous phase. More electrons are transferred from the Pt13 nanocluster to the CeO2 support, implying the supported Pt13 nanocluster is further

The distribution of Th(NO3)4, UO2(NO3)2 and HNO3 between an aqueous phase and an organic tributyl phosphate phase

International Nuclear Information System (INIS)

Nakashima, T.; Zimmer, E.

1984-05-01

The distribution of Th(NO 3 ) 4 , UO 2 (NO 3 ) 2 and HNO 3 between an aqueous phase and an organic phase, consisting of 30 Vol.% tributyl phosphate in dodecane, has been experimentally investigated. About 120 distribution data have been determined in the concentration ranges that can be seen in the THOREX process for reprocessing spent thorium bearing fuel. Based on the experimental data, two computer programs have been developed which make possible interpolations and, to some extent, extrapolations. With model 1, concentrations in the organic phase can be calculated if that in the aqueous phase are known. With model 2, concentrations in the aqueous phase can be calculated vice versa. Besides the description of the calculation models, a large body of calculated data can be found in this report. In a addition, a calculation mode is presented that makes possible the calculation of distribution data for very low thorium concentrations. (orig.) [de

Gas-Phase Oxidation of Aqueous Ethanol by Nanoparticle Vanadia/Anatase Catalysts

DEFF Research Database (Denmark)

Jørgensen, Betina; Kristensen, Steffen Buus; Kunov-Kruse, Andreas Jonas

2009-01-01

The gas-phase oxidation of aqueous ethanol with dioxygen has been examined with a new nanoparticle V2O5/TiO2 catalyst. Product selectivity could to a large extent be controlled by small alterations of reaction parameters, allowing production of acetaldehyde at a selectivity higher than 90%, near...

Adsorptive removal of phthalate ester (Di-ethyl phthalate) from aqueous phase by activated carbon: a kinetic study.

Science.gov (United States)

Venkata Mohan, S; Shailaja, S; Rama Krishna, M; Sarma, P N

2007-07-19

Adsorptive studies were carried out on Di-ethyl phthalate (DEP) removal from aqueous phase onto activated carbon. Batch sorption studies were performed and the results revealed that activated carbon demonstrated ability to adsorb DEP. Influence of varying experimental conditions such as DEP concentration, pH of aqueous solution, and dosage of adsorbent were investigated on the adsorption process. Sorption interaction of DEP onto activated carbon obeyed the pseudo second order rate equation. Experimental data showed good fit with both the Langmuir and Freundlich adsorption isotherm models. DEP sorption was found to be dependent on the aqueous phase pH and the uptake was observed to be greater at acidic pH.

Violent flows in aqueous foams III: physical multi-phase model comparison with aqueous foam shock tube experiments

Science.gov (United States)

Redford, J. A.; Ghidaglia, J.-M.; Faure, S.

2018-06-01

Mitigation of blast waves in aqueous foams is a problem that has a strong dependence on multi-phase effects. Here, a simplified model is developed from the previous articles treating violent flows (D'Alesio et al. in Eur J Mech B Fluids 54:105-124, 2015; Faure and Ghidaglia in Eur J Mech B Fluids 30:341-359, 2011) to capture the essential phenomena. The key is to have two fluids with separate velocities to represent the liquid and gas phases. This allows for the interaction between the two phases, which may include terms for drag, heat transfer, mass transfer due to phase change, added mass effects, to be included explicitly in the model. A good test for the proposed model is provided by two experimental data sets that use a specially designed shock tube. The first experiment has a test section filled with spray droplets, and the second has a range of aqueous foams in the test section. A substantial attenuation of the shock wave is seen in both cases, but a large difference is observed in the sound speeds. The droplets cause no observable change from the air sound speed, while the foams have a reduced sound speed of approximately 50-75 m/s . In the model given here, an added mass term is introduced in the governing equations to capture the low sound speed. The match between simulation and experiment is found to be satisfactory for both droplets and the foam. This is especially good when considering the complexity of the physics and the effects that are unaccounted for, such as three-dimensionality and droplet atomisation. The resulting statistics illuminate the processes occurring in such flows.

The phase transport and reactions of γ-irradiated aqueous-ionic liquids

International Nuclear Information System (INIS)

Howett, S.; Joseph, J.; Noel, J.J.; Wren, J.C.

2010-01-01

A novel technology based on the transfer of chemical species across water/ionic liquid interfaces via specific complexation reactions is currently being considered for the separation and sequestration of metal ion contaminants from radioactive waste effluents in the nuclear fuel cycle. An ideal solvent for these applications should have a high intrinsic selectivity for a targeted metal or group of metals (e.g., trans-Pu actinides, lanthanides, or other fission products), an efficient switching mechanism (between complexation and decomplexation), and a high immiscibility with aqueous solutions. These characteristics must be maintained in the chemical, radiation, and mass transport environments present during the separation process. Ionic liquids (ILs) have an almost negligible vapour pressure and high thermal stability. Their ability to dissolve a wide range of substrate molecules and potential to be highly resilient in radiation fields make ILs particularly promising media. The separation efficiency of the biphasic system will depend on many parameters, including the aqueous oxidation state of the targeted metal ion, and the thermodynamics and kinetics of interfacial transport and metal-ligand complex formation at the water/IL interface or in the IL phase. The most uncertain and unstudied area for these applications is the effect of ionizing radiation on the stability and separation efficiency of the biphasic system. The present study investigates the effect of γ-radiation on gas/IL and water/IL interfacial stability and mass transfer with trihexyltetradecylphosphonium bis(trifluoromethyl-sulfonyl)imide, a phosphonium-based IL. The IL, in contact with either gas or water, was irradiated at a dose rate of 6.4 kGy·h -1 . Gas-phase samples were analyzed by gas chromatography-mass spectrometry (GC-MS) and the changes in the IL and aqueous phases were monitored by conductivity measurements and Raman spectroscopy. In this paper we discuss these observations and their

Analysis of Solid and Aqueous Phase Products from Hydrothermal Carbonization of Whole and Lipid-Extracted Algae

Directory of Open Access Journals (Sweden)

Amber Broch

2013-12-01

Full Text Available Microalgae have tremendous potential as a feedstock for production of liquid biofuels, particularly biodiesel fuel via transesterification of algal lipids. However, biodiesel production results in significant amounts of algal residues, or “lipid extracted algae” (LEA. Suitable utilization of the LEA residue will improve the economics of algal biodiesel. In the present study, we evaluate the hydrothermal carbonization (HTC of whole and lipid extracted algal (Spirulina maxima feedstocks in order to produce a solid biofuel (hydrochar and value-added co-products in the aqueous phase. HTC experiments were performed using a 2-L Parr reactor (batch type at 175–215 °C with a 30-min holding time. Solid, aqueous and gaseous products were analyzed using various laboratory methods to evaluate the mass and carbon balances, and investigate the existence of high value chemicals in the aqueous phase. The HTC method is effective in creating an energy dense, solid hydrochar from both whole algae and LEA at lower temperatures as compared to lignocellulosic feedstocks, and is effective at reducing the ash content in the resulting hydrochar. However, under the treatment temperatures investigated, less than 1% of the starting dry algae mass was recovered as an identified high-value chemical in the aqueous phase.

Purification of Active Myrosinase from Plants by Aqueous Two-Phase Counter-Current Chromatography

Science.gov (United States)

Wade, Kristina L.; Ito, Yoichiro; Ramarathnam, Aarthi; Holtzclaw, W. David; Fahey, Jed W.

2014-01-01

Introduction Myrosinase (thioglucoside glucohydrolase; E.C. 3.2.1.147), is a plant enzyme of increasing interest and importance to the biomedical community. Myrosinase catalyses the formation of isothiocyanates such as sulforaphane (frombroccoli) and 4-(α-l-rhamnopyranosyloxy)benzyl isothiocyanate (from moringa), which are potent inducers of the cytoprotective phase-2 response in humans, by hydrolysis of their abundant glucosinolate (β-thioglucoside N-hydroxysulphate) precursors. Objective To develop an aqueous two-phase counter-current chromatography (CCC) system for the rapid, three-step purification of catalytically active myrosinase. Methods A high-concentration potassium phosphate and polyethylene glycol biphasic aqueous two-phase system (ATPS) is used with a newly developed CCC configuration that utilises spiral-wound, flat-twisted tubing (with an ovoid cross-section). Results Making the initial crude plant extract directly in the ATPS and injecting only the lower phase permitted highly selective partitioning of the myrosinase complex before a short chromatography on a spiral disk CCC. Optimum phase retention and separation of myrosinase from other plant proteins afforded a 60-fold purification. Conclusion Catalytically active myrosinase is purified from 3-day broccoli sprouts, 7-day daikon sprouts, mustard seeds and the leaves of field-grown moringa trees, in a CCC system that is predictably scalable. PMID:25130502

Purification of active myrosinase from plants by aqueous two-phase counter-current chromatography.

Science.gov (United States)

Wade, Kristina L; Ito, Yoichiro; Ramarathnam, Aarthi; Holtzclaw, W David; Fahey, Jed W

2015-01-01

Myrosinase (thioglucoside glucohydrolase; E.C. 3.2.1.147), is a plant enzyme of increasing interest and importance to the biomedical community. Myrosinase catalyses the formation of isothiocyanates such as sulforaphane (from broccoli) and 4-(α-l-rhamnopyranosyloxy)benzyl isothiocyanate (from moringa), which are potent inducers of the cytoprotective phase-2 response in humans, by hydrolysis of their abundant glucosinolate (β-thioglucoside N-hydroxysulphate) precursors. To develop an aqueous two-phase counter-current chromatography (CCC) system for the rapid, three-step purification of catalytically active myrosinase. A high-concentration potassium phosphate and polyethylene glycol biphasic aqueous two-phase system (ATPS) is used with a newly developed CCC configuration that utilises spiral-wound, flat-twisted tubing (with an ovoid cross-section). Making the initial crude plant extract directly in the ATPS and injecting only the lower phase permitted highly selective partitioning of the myrosinase complex before a short chromatography on a spiral disk CCC. Optimum phase retention and separation of myrosinase from other plant proteins afforded a 60-fold purification. Catalytically active myrosinase is purified from 3-day broccoli sprouts, 7-day daikon sprouts, mustard seeds and the leaves of field-grown moringa trees, in a CCC system that is predictably scalable. Copyright © 2014 John Wiley & Sons, Ltd.

A review of catalytic aqueous-phase reforming of oxygenated hydrocarbons derived from biorefinery water fractions

NARCIS (Netherlands)

Coronado, I.; Stekrova, M.; Reinikainen, M.; Simell, P.; Lefferts, Leonardus; Lehtonen, J.

2016-01-01

Aqueous-phase reforming (APR) of oxygenated hydrocarbons is a process for the production of hydrogen and light alkanes. The reactants of APR remain in liquid phase during the reaction avoiding an energetically demanding vaporization-step compared to processes such as steam reforming (SR).

Aqueous two-phase systems for extractive enzymatic hydrolysis of biomass

DEFF Research Database (Denmark)

Bussamra, Bianca Consorti; Azzoni, Sindelia Freitas; Mussatto, Solange I.

and enzymes, phase diagrams and volumetric ratios. The results of this project will make possible to design a process that enables high sugar concentration during the hydrolysis reaction, overcoming one of the biggest drawbacks regarding the production of second-generation ethanol: the enzymatic inhibition...... optimal aqueous two-phase systems for the separation of sugars and enzymes, which allow the development of an improved second-generation ethanol process.......Sugars derived from lignocellulosic materials are the main carbon sources in bio-based processes aiming to produce renewable fuels and chemicals. One of the major drawbacks during enzymatic hydrolysis of lignocellulosic materials to obtainsugars is the inhibition of enzymes by reaction products...

Internally consistent thermodynamic data for aqueous species in the system Na-K-Al-Si-O-H-Cl

Science.gov (United States)

Miron, George D.; Wagner, Thomas; Kulik, Dmitrii A.; Heinrich, Christoph A.

2016-08-01

A large amount of critically evaluated experimental data on mineral solubility, covering the entire Na-K-Al-Si-O-H-Cl system over wide ranges in temperature and pressure, was used to simultaneously refine the standard state Gibbs energies of aqueous ions and complexes in the framework of the revised Helgeson-Kirkham-Flowers equation of state. The thermodynamic properties of the solubility-controlling minerals were adopted from the internally consistent dataset of Holland and Powell (2002; Thermocalc dataset ds55). The global optimization of Gibbs energies of aqueous species, performed with the GEMSFITS code (Miron et al., 2015), was set up in such a way that the association equilibria for ion pairs and complexes, independently derived from conductance and potentiometric data, are always maintained. This was achieved by introducing reaction constraints into the parameter optimization that adjust Gibbs energies of complexes by their respective Gibbs energy effects of reaction, whenever the Gibbs energies of reactant species (ions) are changed. The optimized thermodynamic dataset is reported with confidence intervals for all parameters evaluated by Monte Carlo trial calculations. The new thermodynamic dataset is shown to reproduce all available fluid-mineral phase equilibria and mineral solubility data with good accuracy and precision over wide ranges in temperature (25-800 °C), pressure (1 bar to 5 kbar) and composition (salt concentrations up to 5 molal). The global data optimization process adopted in this study can be readily repeated any time when extensions to new chemical elements and species are needed, when new experimental data become available, or when a different aqueous activity model or equation of state should be used. This work serves as a proof of concept that our optimization strategy is feasible and successful in generating a thermodynamic dataset reproducing all fluid-mineral and aqueous speciation equilibria in the Na-K-Al-Si-O-H-Cl system within

Phase Diagrams of the Aqueous Two-Phase Systems of Poly(ethylene glycol/Sodium Polyacrylate/Salts

Directory of Open Access Journals (Sweden)

Adalberto Pessoa Junior

2011-03-01

Full Text Available Aqueous two-phase systems consisting of polyethylene glycol (PEG, sodium polyacrylate (NaPAA, and a salt have been studied. The effects of the polymer size, salt type (NaCl, Na2SO4, sodium adipate and sodium azelate and salt concentrations on the position of the binodal curve were investigated. The investigated PEG molecules had a molar mass of 2,000 to 8,000 g/mol, while that of NaPAA was 8,000 g/mol. Experimental phase diagrams, and tie lines and calculated phase diagrams, based on Flory-Huggins theory of polymer solutions are presented. Due to strong enthalpic and entropic balancing forces, the hydrophobicity of the added salt has a strong influence on the position of the binodal, which could be reproduced by model calculations.

Solid phase microextraction speciation analysis of triclosan in aqueous mediacontaining sorbing nanoparticles

NARCIS (Netherlands)

Zielinska, K.

2014-01-01

Solid phase microextraction (SPME) is applied in the speciation analysis of the hydrophobic compound triclosan in an aqueous medium containing sorbing SiO2 nanoparticles (NPs). It is found that these NPs, as well as their complexes with triclosan, partition between the bulk medium and the solid

Hydrogen production through aqueous-phase reforming of ethylene glycol in a washcoated microchannel

NARCIS (Netherlands)

Neira d'Angelo, M.F.; Ordomskiy, V.; Paunovic, V.; Schaaf, van der J.; Schouten, J.C.; Nijhuis, T.A.

2013-01-01

Aqueous-phase reforming (APR) of biocarbohydrates is conducted in a catalytically stable washcoated microreactor where multiphase hydrogen removal enhances hydrogen efficiency. Single microchannel experiments are conducted following a simplified model based on the microreactor concept. A coating

Recovery of Picloram and 2,4-Dichlorophenoxyacetic Acid from Aqueous Samples by Reversed-Phase Solid-Phase Extraction

Science.gov (United States)

Martha J.M. Wells; Jerry L. Michael

1987-01-01

Extensive preparation of samples before chromatographic analysis is usually the most time-consuming process in the determination of many organic compounds in environmental matrices. In the past, removal of some organic from aqueous solution was commonly done by liquid/liquid extraction. However, the introduction of stable, covalently bonded reversed-phase sorbents now...

A Novel Aqueous Two Phase System Composed of Surfactant and Xylitol for the Purification of Lipase from Pumpkin (Cucurbita moschata) Seeds and Recycling of Phase Components.

Science.gov (United States)

Amid, Mehrnoush; Manap, Mohd Yazid; Hussin, Muhaini; Mustafa, Shuhaimi

2015-06-17

Lipase is one of the more important enzymes used in various industries such as the food, detergent, pharmaceutical, textile, and pulp and paper sectors. A novel aqueous two-phase system composed of surfactant and xylitol was employed for the first time to purify lipase from Cucurbita moschata. The influence of different parameters such as type and concentration of surfactants, and the composition of the surfactant/xylitol mixtures on the partitioning behavior and recovery of lipase was investigated. Moreover, the effect of system pH and crude load on the degree of purification and yield of the purified lipase were studied. The results indicated that the lipase was partitioned into the top surfactant rich phase while the impurities partitioned into the bottom xylitol-rich phase using an aqueous two phase system composed of 24% (w/w) Triton X-100 and 20% (w/w) xylitol, at 56.2% of tie line length (TLL), (TTL is one of the important parameters in this study and it is determined from a bimodal curve in which the tie-line connects two nodes on the bimodal, that represent concentration of phase components in the top and bottom phases) and a crude load of 25% (w/w) at pH 8.0. Recovery and recycling of components was also measured in each successive step process. The enzyme was successfully recovered by the proposed method with a high purification factor of 16.4 and yield of 97.4% while over 97% of the phase components were also recovered and recycled. This study demonstrated that the proposed novel aqueous two phase system method is more efficient and economical than the traditional aqueous two phase system method for the purification and recovery of the valuable enzyme lipase.

A Novel Aqueous Two Phase System Composed of Surfactant and Xylitol for the Purification of Lipase from Pumpkin (Cucurbita moschata Seeds and Recycling of Phase Components

Directory of Open Access Journals (Sweden)

Mehrnoush Amid

2015-06-01

Full Text Available Lipase is one of the more important enzymes used in various industries such as the food, detergent, pharmaceutical, textile, and pulp and paper sectors. A novel aqueous two-phase system composed of surfactant and xylitol was employed for the first time to purify lipase from Cucurbita moschata. The influence of different parameters such as type and concentration of surfactants, and the composition of the surfactant/xylitol mixtures on the partitioning behavior and recovery of lipase was investigated. Moreover, the effect of system pH and crude load on the degree of purification and yield of the purified lipase were studied. The results indicated that the lipase was partitioned into the top surfactant rich phase while the impurities partitioned into the bottom xylitol-rich phase using an aqueous two phase system composed of 24% (w/w Triton X-100 and 20% (w/w xylitol, at 56.2% of tie line length (TLL, (TTL is one of the important parameters in this study and it is determined from a bimodal curve in which the tie-line connects two nodes on the bimodal, that represent concentration of phase components in the top and bottom phases and a crude load of 25% (w/w at pH 8.0. Recovery and recycling of components was also measured in each successive step process. The enzyme was successfully recovered by the proposed method with a high purification factor of 16.4 and yield of 97.4% while over 97% of the phase components were also recovered and recycled. This study demonstrated that the proposed novel aqueous two phase system method is more efficient and economical than the traditional aqueous two phase system method for the purification and recovery of the valuable enzyme lipase.

Differentiation of surface properties of chlorococcalean algae by means of aqueous two phase systems

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Jan Burczyk

2014-01-01

Full Text Available Algal cells belonging to various strains of Chlorococcales (Chlorophyta have been partitioned in aqueous two-phase systems containing ionogenic polymers, DEAE-dextran or SDS-dextran, at various pH values. Strain-specific differences of partition type which have been found in the phase systems used can be useful for distinguishing of algal cells.

Ru decorated carbon nanotubes - a promising catalyst for reforming bio-based acetic acid in the aqueous phase

NARCIS (Netherlands)

de Vlieger, Dennis; Lefferts, Leonardus; Seshan, Kulathuiyer

2014-01-01

Catalytic reforming of biomass derived waste streams in the aqueous phase is a promising process for the production of sustainable hydrogen. Acetic acid will be a major component (up to 20 wt%) in many anticipated gasification feed streams (e.g. the aqueous fraction of pyrolysis oil). Conventional

PARTITION EFFICIENCY OF NEWLY DESIGNED LOCULAR MULTILAYER COIL FOR COUNTERCURRENT CHROMATOGRAPHIC SEPARATION OF PROTEINS USING SMALL-SCALE CROSS-AXIS COIL PLANET CENTRIFUGE WITH AQUEOUS-AQUEOUS POLYMER PHASE SYSTEMS.

Science.gov (United States)

Shinomiya, Kazufusa; Ito, Yoichiro

2009-01-01

Countercurrent chromatographic performance of the locular multilayer coil separation column newly designed in our laboratory was evaluated in terms of theoretical plate number, peak resolution and retention of the stationary phase in protein separation with an aqueous polymer phase system using the small-scale cross-axis coil planet centrifuge (X-axis CPC) fabricated in our laboratory. The locular column was made from 1.0 mm I.D., 2.0 mm O.D. or 1.5 mm I.D., 2.5 mm O.D. PTFE tubing compressed with a pair of hemostat at 2 or 4 cm intervals. The protein separation was performed using a set of stable proteins including cytochrome C, myoglobin and lysozyme with the 12.5% (w/w) polyethylene glycol 1000 and 12.5% (w/w) dibasic potassium phosphate system under 1000 rpm of column revolution. The 1.5 mm I.D., 2.5 mm O.D. locular tubing compressed at 2 cm intervals yielded better partition efficiencies than the non-clamped tubing using both lower and upper mobile phases with satisfactory retention of the stationary phase. The overall results suggest that the newly designed locular multilayer coil is useful to the preparative separation of proteins with aqueous-aqueous polymer phase system using our small-scale X-axis CPC.

“Towards building better linkages between aqueous phase chemistry and microphysics in CMAQ”

Science.gov (United States)

Currently, CMAQ’s aqueous phase chemistry routine (AQCHEM-base) assumes Henry’s Law equilibrium and employs a forward Euler method to solve a small set of oxidation equations, considering the additional processes of aitken scavenging and wet deposition in series and e...

Microalgae growth on the aqueous phase from Hydrothermal Liquefaction of the same microalgae

NARCIS (Netherlands)

Garcia Alba, Laura; Torri, Cristian; Fabbri, Daniele; Kersten, Sascha R.A.; Brilman, Derk Willem Frederik

2013-01-01

Cultivation of Desmodesmus sp. microalgae in the recycled aqueous phase (AP) recovered after Hydrothermal Liquefaction (HTL) of the same microalgae was studied to evaluate the potential of nutrients recycling. AP dilution ratio was systematically varied, using either water or water enriched with

Phase 1 remediation of jet fuel contaminated soil and groundwater at JFK International Airport using dual phase extraction and bioventing

International Nuclear Information System (INIS)

Roth, R.; Bianco, P. Rizzo, M.

1995-01-01

Soil and groundwater contaminated with jet fuel at Terminal One of the JFK International Airport in New York have been remediated using dual phase extraction (DPE) and bioventing. Two areas were remediated using 51 DPE wells and 20 air sparging/air injection wells. The total area remediated by the DPE wells is estimated to be 4.8 acres. Groundwater was extracted to recover nonaqueous phase and aqueous phase jet fuel from the shallow aquifer and treated above ground by the following processes; oil/water separation, iron-oxidation, flocculation, sedimentation, filtration, air stripping and liquid-phase granular activated carbon (LPGAC) adsorption. The extracted vapors were treated by vapor-phase granular activated carbon (VPGAC) adsorption in one area, and catalytic oxidation and VPGAC adsorption in another area. After 6 months of remediation, approximately 5,490 lbs. of volatile organic compounds (VOCs) were removed by soil vapor extraction (SVE), 109,650 lbs. of petroleum hydrocarbons were removed from the extracted groundwater, and 60,550 lbs. of petroleum hydrocarbons were biologically oxidized by subsurface microorganisms. Of these three mechanisms, the rate of petroleum hydrocarbon removal was the highest for biological oxidation in one area and by groundwater extraction in another area

A chromatographic determination of water in non-aqueous phases of solvent extraction systems

International Nuclear Information System (INIS)

Lyle, S.J.; Smith, D.B.

1975-01-01

The disadvantages of the Karl Fischer method for the determination of water in the non-aqueous phases of solvent extraction systems are pointed out, and a gas chromatographic method is described which is claimed to be potentially capable of overcoming these disadvantages. The method, as described, was developed to satisfy conditions relevant to measurement of the transfer rate of water from an aqueous phase into tri-n-butylphosphate in toluene, but it can be used for water determination in other solvent extraction systems. The apparatus used is described in detail. The concentration of water in water-saturated TBP was found to be 3.56 mol/litre, compared with a value of 3.55 obtained by Karl Fischer titration and previous literature values of 3.59 and 3.57. Measurements of water content in benzene solutions of long chain alkylamines were also sucessfully carried out. (U.K.)

Study of complex formation of cobalt (II) and cobalt (III) in acrylamide aqueous solutions and in the phase of acrylamide hydrogel

International Nuclear Information System (INIS)

Ismailova, M.M.; Egorova, L.A.; Khamidov, B.O.

1993-01-01

Present article is devoted to study of complex formation of cobalt (II) and cobalt (III) in acrylamide aqueous solutions and in the phase of acrylamide hydrogel. The condition of cobalt in various rate of oxidation in acrylamide aqueous solutions was studied. The concentration conditions of stability of system Co(II)-Co(III) were defined. The composition of coordination compounds of cobalt (II) and cobalt (III) in acrylamide aqueous solutions and in the phase of acrylamide hydrogel was determined.

Bioreactor droplets from liposome-stabilized all-aqueous emulsions

Science.gov (United States)

Dewey, Daniel C.; Strulson, Christopher A.; Cacace, David N.; Bevilacqua, Philip C.; Keating, Christine D.

2014-08-01

Artificial bioreactors are desirable for in vitro biochemical studies and as protocells. A key challenge is maintaining a favourable internal environment while allowing substrate entry and product departure. We show that semipermeable, size-controlled bioreactors with aqueous, macromolecularly crowded interiors can be assembled by liposome stabilization of an all-aqueous emulsion. Dextran-rich aqueous droplets are dispersed in a continuous polyethylene glycol (PEG)-rich aqueous phase, with coalescence inhibited by adsorbed ~130-nm diameter liposomes. Fluorescence recovery after photobleaching and dynamic light scattering data indicate that the liposomes, which are PEGylated and negatively charged, remain intact at the interface for extended time. Inter-droplet repulsion provides electrostatic stabilization of the emulsion, with droplet coalescence prevented even for submonolayer interfacial coatings. RNA and DNA can enter and exit aqueous droplets by diffusion, with final concentrations dictated by partitioning. The capacity to serve as microscale bioreactors is established by demonstrating a ribozyme cleavage reaction within the liposome-coated droplets.

Thermodynamic modelling of phase equilibrium for water + poly(Ethylene glycol + salt aqueous two-phase systems

Directory of Open Access Journals (Sweden)

R.A.G. Sé

2002-04-01

Full Text Available The NRTL (nonrandom, two-liquid model, expressed in mass fraction instead of mole fraction, was used to correlate liquid-liquid equilibria for aqueous two-phase polymer-salt solutions. New interaction energy parameters for this model were determined using reported data on the water + poly(ethylene glycol + salt systems, with different molecular masses for PEG and the salts potassium phosphate, sodium sulfate, sodium carbonate and magnesium sulfate. The correlation of liquid-liquid equilibrium is quite satisfactory.

Glycine phases formed from frozen aqueous solutions: Revisited

Energy Technology Data Exchange (ETDEWEB)

Surovtsev, N. V. [Institute of Automation and Electrometry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Adichtchev, S. V.; Malinovsky, V. K. [Institute of Automation and Electrometry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Ogienko, A. G.; Manakov, A. Yu. [Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Drebushchak, V. A. [Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Institute of Geology and Mineralogy, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Ancharov, A. I.; Boldyreva, E. V. [Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Institute of Solid Chemistry and Mechanochemistry, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Yunoshev, A. S. [Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Lavrentiev Institute of Hydrodynamics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation)

2012-08-14

Glycine phases formed when aqueous solutions were frozen and subsequently heated under different conditions were studied by Raman scattering, x-ray diffraction, and differential scanning calorimetry (DSC) techniques. Crystallization of ice I{sub h} was observed in all the cases. On cooling at the rates of 0.5 K/min and 5 K/min, glassy glycine was formed as an intermediate phase which lived about 1 min or less only, and then transformed into {beta}-polymorph of glycine. Quench cooling of glycine solutions (15% w/w) in liquid nitrogen resulted in the formation of a mixture of crystalline water ice I{sub h} and a glassy glycine, which could be preserved at cryogenic temperatures (80 K) for an indefinitely long time. This mixture remained also quite stable for some time after heating above the cryogenic temperature. Subsequent heating under various conditions resulted in the transformation of the glycine glass into an unknown crystalline phase (glycine 'X-phase') at 209-216 K, which at 218-226 K transformed into {beta}-polymorph of glycine. The 'X-phase' was characterized by Raman spectroscopy; it could be obtained in noticeable amounts using a special preparation technique and tentatively characterized by x-ray powder diffraction (P2, a= 6.648 A, b= 25.867 A, c= 5.610 A, {beta}= 113.12 Masculine-Ordinal-Indicator ); the formation of 'X-phase' from the glycine glassy phase and its transformation into {beta}-polymorph were followed by DSC. Raman scattering technique with its power for unambiguous identification of the crystalline and glassy polymorphs without limitation on the crystallite size helped us to follow the phase transformations during quenching, heating, and annealing. The experimental findings are considered in relation to the problem of control of glycine polymorphism on crystallization.

Glycine phases formed from frozen aqueous solutions: Revisited

Science.gov (United States)

Surovtsev, N. V.; Adichtchev, S. V.; Malinovsky, V. K.; Ogienko, A. G.; Drebushchak, V. A.; Manakov, A. Yu.; Ancharov, A. I.; Yunoshev, A. S.; Boldyreva, E. V.

2012-08-01

Glycine phases formed when aqueous solutions were frozen and subsequently heated under different conditions were studied by Raman scattering, x-ray diffraction, and differential scanning calorimetry (DSC) techniques. Crystallization of ice Ih was observed in all the cases. On cooling at the rates of 0.5 K/min and 5 K/min, glassy glycine was formed as an intermediate phase which lived about 1 min or less only, and then transformed into β-polymorph of glycine. Quench cooling of glycine solutions (15% w/w) in liquid nitrogen resulted in the formation of a mixture of crystalline water ice Ih and a glassy glycine, which could be preserved at cryogenic temperatures (80 K) for an indefinitely long time. This mixture remained also quite stable for some time after heating above the cryogenic temperature. Subsequent heating under various conditions resulted in the transformation of the glycine glass into an unknown crystalline phase (glycine "X-phase") at 209-216 K, which at 218-226 K transformed into β-polymorph of glycine. The "X-phase" was characterized by Raman spectroscopy; it could be obtained in noticeable amounts using a special preparation technique and tentatively characterized by x-ray powder diffraction (P2, a = 6.648 Å, b = 25.867 Å, c = 5.610 Å, β = 113.12°); the formation of "X-phase" from the glycine glassy phase and its transformation into β-polymorph were followed by DSC. Raman scattering technique with its power for unambiguous identification of the crystalline and glassy polymorphs without limitation on the crystallite size helped us to follow the phase transformations during quenching, heating, and annealing. The experimental findings are considered in relation to the problem of control of glycine polymorphism on crystallization.

[Phase transfer catalyzed bioconversion of penicillin G to 6-APA by immobilized penicillin acylase in recyclable aqueous two-phase systems with light/pH sensitive copolymers].

Science.gov (United States)

Jin, Ke-ming; Cao, Xue-jun; Su, Jin; Ma, Li; Zhuang, Ying-ping; Chu, Ju; Zhang, Si-liang

2008-03-01

Immobilized penicillin acylase was used for bioconversion of penicillin PG into 6-APA in aqueous two-phase systems consisting of a light-sensitive polymer PNBC and a pH-sensitive polymer PADB. Partition coefficients of 6-APA was found to be about 5.78 in the presence of 1% NaCl. Enzyme kinetics showed that the reaction reached equilibrium at roughly 7 h. The 6-APA mole yields were 85.3% (pH 7.8, 20 degrees C), with about 20% increment as compared with the reaction of single aqueous phase buffer. The partition coefficient of PG (Na) varied scarcely, while that of the product, 6-APA and phenylacetic acid (PA) significantly varied due to Donnan effect of the phase systems and hydrophobicity of the products. The variation of the partition coefficients of the products also affected the bioconversion yield of the products. In the aqueous two-phase systems, the substrate, PG, the products of 6-APA and PA were biased in the top phase, while immobilized penicillin acylase at completely partitioned at the bottom. The substrate and PG entered the bottom phase, where it was catalyzed into 6-APA and PA and entered the top phase. Inhibition of the substrate and products was removed to result in improvement of the product yield, and the immobilized enzyme showed higher efficiency than the immobilized cells and occupied smaller volume. Compared with the free enzyme, immobilized enzyme had greater stability, longer life-time, and was completely partitioned in the bottom phase and recycle. Bioconversion in two-phase systems using immobilized penicillin acylase showed outstanding advantage. The light-sensitive copolymer forming aqueous two-phase systems could be recovered by laser radiation at 488 nm or filtered 450 nm light, while pH-sensitive polymer PADB could be recovered at the isoelectric point (pH 4.1). The recovery of the two copolymers was between 95% and 99%.

Formation of aqueous-phase α-hydroxyhydroperoxides (α-HHP: potential atmospheric impacts

Directory of Open Access Journals (Sweden)

R. Zhao

2013-06-01

Full Text Available The focus of this work is on quantifying the degree of the aqueous-phase formation of α-hydroxyhydroperoxides (α-HHPs via reversible nucleophilic addition of H2O2 to aldehydes. Formation of this class of highly oxygenated organic hydroperoxides represents a poorly characterized aqueous-phase processing pathway that may lead to enhanced SOA formation and aerosol toxicity. Specifically, the equilibrium constants of α-HHP formation have been determined using proton nuclear-magnetic-resonance (1H NMR spectroscopy and proton-transfer-reaction mass spectrometry (PTR-MS. Significant α-HHP formation was observed from formaldehyde, acetaldehyde, propionaldehyde, glycolaldehyde, glyoxylic acid, and methylglyoxal, but not from methacrolein and ketones. Low temperatures enhanced the formation of α-HHPs but slowed their formation rates. High inorganic salt concentrations shifted the equilibria toward the hydrated form of the aldehydes and slightly suppressed α-HHP formation. Using the experimental equilibrium constants, we predict the equilibrium concentration of α-HHPs to be in the μM level in cloud water, but it may also be present in the mM level in aerosol liquid water (ALW, where the concentrations of H2O2 and aldehydes can be high. Formation of α-HHPs in ALW may significantly affect the effective Henry's law constants of H2O2 and aldehydes but may not affect their gas-phase levels. The photochemistry and reactivity of this class of atmospheric species have not been studied.

Platinum–Rhenium synergy on reducible oxide supports in aqueous-phase glycerol reforming

NARCIS (Netherlands)

Ciftci, A.; Eren, S.; Ligthart, D.A.J.M.; Hensen, E.J.M.

2014-01-01

A significant support effect was observed for the aqueous-phase reforming (APR) of glycerol over a series of Pt- and PtRe-loaded ceria-, ceria–zirconia-, zirconia-, and titania-supported catalysts. Glycerol conversion rates decreased in the order Pt/TiO2>Pt/ZrO2>Pt/CeZrO2>Pt/CeO2. Upon addition of

Extraction of lithium ion from alkaline aqueous media by a liquid surfactant membrane

International Nuclear Information System (INIS)

Kinugasa, Takumi; Ono, Yuri; Kawamura, Yuko; Watanabe, Kunio; Takeuchi, Hiroshi.

1995-01-01

Extraction of lithium ion from aqueous alkaline media by a liquid surfactant membrane was performed using a mixture of LIX54 and TOPO as the extractant. Stripping of lithium from the kerosene solution to the acid solution was suppressed with increasing content of polyamine (ECA) surfactant. The extraction rate of lithium by the liquid membrane could be interpreted taking account of an interfacial resistance due to ECA. It was confirmed that swelling of the (W/O) emulsion drops by water permeation through the liquid membrane is evaluated in terms of a change in osmotic pressure gradient between the external and internal aqueous phases during the lithium extraction. In the present operation, the extraction ratio of Li + from the external feed and the uptake into the internal phase reached as high as 95%. (author)

Cosolutes effects on aqueous two-phase systems equilibrium formation studied by physical approaches.

Science.gov (United States)

Bertoluzzo, M Guadalupe; Rigatuso, Rubén; Farruggia, Beatriz; Nerli, Bibiana; Picó, Guillermo

2007-10-01

The effect of urea and sodium salts of monovalent halides on the aqueous polyethyleneglycol solution and binodal diagrams of polyethyleneglycol-potassium phosphate (polyethyleneglycol of molecular mass 1500, 4000, 6000 and 8000) were studied using different physical approaches. The effect of these solutes on the binodal diagram for polyethyleneglycol-potassium phosphate was also investigated. The cosolutes affected in a significant manner the water structured around the ethylene chain of polyethyleneglycol inducing a lost of this. The equilibrium curves for the aqueous two-phase systems were fitting very well by a sigmoidal function with two parameters, which are closely related with the cosolute structure making or breaking capacity on the water ordered.

Formation of the second organic phase during uranyl nitrate extraction from aqueous solution by 30% tributylphosphate solution in paraffin

International Nuclear Information System (INIS)

Yhrkin, V.G.

1996-01-01

For extraction systems aqueous solution of uranyl nitrate-30% solution of tributylphosphate in individual paraffins from C 13 to C 17 the influence of the second organic phase of uranyl nitrate concentration in aqueous and organic phases, the length of hydrocarbon chain of paraffin hydrocarbon and temperature from 25 to 50 deg C on formation conditions has been defected. A special method of achieving the conditions of organic phase stratification from three-phase region, involving definition of equilibrium phases composition by density and refractive index, has been elaborated for more precise definition of organic phase homogeneity region. It has been revealed that without addition of nitric acid to uranyl nitrate solution the organic phase homogeneity limits can be achieved solely on paraffins C 15 , C 16 and C 17 and only under conditions similar to equeous phase saturation in terms of uranyl nitrate. 16 refs., 2 figs

Improving the treatment of non-aqueous phase TCE in low permeability zones with permanganate.

Science.gov (United States)

Chokejaroenrat, Chanat; Comfort, Steve; Sakulthaew, Chainarong; Dvorak, Bruce

2014-03-15

Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO4(-)) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase (14)C-TCE. The treatments we evaluated included permanganate paired with: (i) a shear-thinning polymer (xanthan); (ii) stabilization aids that minimized MnO2 rind formation and (iii) a phase-transfer catalyst. In addition, we quantified the ability of these flooding solutions to improve TCE destruction under batch conditions by developing miniature LPZ cylinders that were spiked with (14)C-TCE. Transport experiments showed that MnO4(-) alone was inefficient in penetrating the LPZ and reacting with non-aqueous phase TCE, due to a distinct and large MnO2 rind that inhibited the TCE from further oxidant contact. By including xanthan with MnO4(-), the sweeping efficiency increased (90%) but rind formation was still evident. By including the stabilization aid, sodium hexametaphosphate (SHMP) with xanthan, permanganate penetrated 100% of the LPZ, no rind was observed, and the percentage of TCE oxidized increased. Batch experiments using LPZ cylinders allowed longer contact times between the flooding solutions and the DNAPL and results showed that SHMP+MnO4(-) improved TCE destruction by ∼16% over MnO4(-) alone (56.5% vs. 40.1%). These results support combining permanganate with SHMP or SHMP and xanthan as a means of treating high concentrations of TCE in low permeable zones. Copyright © 2014 Elsevier B.V. All rights reserved.

Aqueous Two-Phase Extraction of Polyphenols Using a Microchannel System – Process Optimization and Intensification

Directory of Open Access Journals (Sweden)

Ivana Rukavina

2011-01-01

Full Text Available Polyphenols are one of the most numerous and widespread groups of compounds in the plant world. Nowadays, organic solvents such as methanol, ethanol, acetone, dimethylformamide, ethyl acetate and diethylether are mainly used for the extraction of polyphenols. These solvents require special process conditions and special care in the disposal of the used solvents. In this paper, the extraction of polyphenols from the model solution was performed using the aqueous two-phase system which contains 80.90 % water and represents low burden on the environment. The aqueous solution of gallic acid (GA was used as a model solution of polyphenols. The extraction was performed in the aqueous two-phase system containing PEG6000/H2O/(NH42SO4 in a macroextractor (V=10 mL and microextractor (V=14 ƒμL. The influence of the process parameters, the concentration of gallic acid, pH and composition of the aqueous two-phase system was investigated in order to maximize the partition coefficient. The method of multifactor experimental planning was used to optimize the extraction process and the results were statistically analysed using the evolutionary operation method (EVOP. Optimal operating conditions of the extraction process were pH=6.50, γGA=4.50 g/L, the mass fraction of polyethylene glycol (PEG wPEG=0.1037 g/g and the mass fraction of ammonium sulphate (AMS wAMS=0.0925 g/g. Under these conditions the maximal partition coefficient of K=5.54 and the extraction efficiency of E=89.11 % were achieved and successfully applied for total phenol extraction from white wine in the macro- and microextractor. Approximately the same partition coefficients and extraction efficiency were achieved in the microextractor within a 60-fold shorter residence time.

Aqueous-phase reforming of crude glycerol : effect of impurities on hydrogen production

NARCIS (Netherlands)

Boga, Dilek A.; Liu, Fang; Bruijnincx, Pieter C. A.; Weckhuysen, Bert M.

2016-01-01

The aqueous-phase reforming (APR) of a crude glycerol that originates from an industrial process and the effect of the individual components of crude glycerol on APR activity have been studied over 1 wt% Pt/Mg-Al) O, 1 wt% Pt/Al2O3, 5 wt% Pt/Al2O3 and 5 wt% Pt/C catalysts at 29 bar and 225 degrees

Separation of four flavonol glycosides from Solanum rostratum Dunal using aqueous two-phase flotation followed by preparative high-performance liquid chromatography.

Science.gov (United States)

Chang, Lin; Shao, Qian; Xi, Xingjun; Chu, Qiao; Wei, Yun

2017-02-01

Aqueous two-phase flotation followed by preparative high-performance liquid chromatography was used to separate four flavonol glycosides from Solanum rostratum Dunal. In the aqueous two-phase flotation section, the effects of sublation solvent, solution pH, (NH 4 ) 2 SO 4 concentration in aqueous solution, cosolvent, N 2 flow rate, flotation time, and volumes of the polyethylene glycol phase on the recovery were investigated in detail, and the optimal conditions were selected: 50 wt% polyethylene glycol 1000 ethanol solvent as the flotation solvent, pH 4, 350 g/L of (NH 4 ) 2 SO 4 concentration in aqueous phase, 40 mL/min of N 2 flow rate, 30 min of flotation time, 10.0 mL of flotation solvent volume, and two times. After aqueous two-phase flotation concentration, the flotation products were purified by preparative high-performance liquid chromatography. The purities of the final products A and B were 98.1 and 99.0%. Product B was the mixture of three compounds based on the analysis of high-performance liquid chromatography at the temperature of 10°C, while product A was hyperoside after the identification by nuclear magnetic resonance. Astragalin, 3'-O-methylquercetin 3-O-β-d-galactopyranoside, and 3'-O-methylquercetin 3-O-β-d-glucopyranoside were obtained with the purity of 93.8, 97.1, and 99.2%, respectively, after the further separation of product B using preparative high-performance liquid chromatography. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

POLYELECTROLYTE MULTILAYER STAMPING IN AQUEOUS PHASE AND NON-CONTACT MODE

Science.gov (United States)

Mehrotra, Sumit; Lee, Ilsoon; Liu, Chun; Chan, Christina

2011-01-01

Polyelectrolyte multilayer (PEM) transfer printing has been previously achieved by stamping under dry conditions. Here, we show for the first time, that PEM can be transferred from a stamp to the base substrate under aqueous conditions whereby the two surfaces are in a non-contact mode. Degradable multilayers of (PAA/PEG)10.5 followed by non-degradable multilayers of (PDAC/SPS)80.5 were fabricated under acidic pH conditions on either PDMS or glass (stamp), and subsequently transferred over top of another multilayer prepared on a different substrate (base substrate), with a spacing of ~ 200 μm between the stamping surface and the base substrate. This multilayer transfer was performed under physiological pH conditions. This process is referred to herein as non-contact, aqueous-phase multilayer (NAM) transfer. NAM transfer can be useful for applications such as fabricating three-dimensional (3-D) cellular scaffolds. We attempted to create a 3-D cellular scaffold using NAM transfer, and characterized the scaffolds with conventional and fluorescence microscopy. PMID:21860540

Integration of carboxyl modified magnetic particles and aqueous two-phase extraction for selective separation of proteins.

Science.gov (United States)

Gai, Qingqing; Qu, Feng; Zhang, Tao; Zhang, Yukui

2011-07-15

Both of the magnetic particle adsorption and aqueous two-phase extraction (ATPE) were simple, fast and low-cost method for protein separation. Selective proteins adsorption by carboxyl modified magnetic particles was investigated according to protein isoelectric point, solution pH and ionic strength. Aqueous two-phase system of PEG/sulphate exhibited selective separation and extraction for proteins before and after magnetic adsorption. The two combination ways, magnetic adsorption followed by ATPE and ATPE followed by magnetic adsorption, for the separation of proteins mixture of lysozyme, bovine serum albumin, trypsin, cytochrome C and myloglobin were discussed and compared. The way of magnetic adsorption followed by ATPE was also applied to human serum separation. Copyright © 2011 Elsevier B.V. All rights reserved.

Supercooling of aqueous dimethylsulfoxide solution at normal and high pressures: Evidence for the coexistence of phase-separated aqueous dimethylsulfoxide solutions of different water structures

Science.gov (United States)

Kanno, H.; Kajiwara, K.; Miyata, K.

2010-05-01

Supercooling behavior of aqueous dimethylsulfoxide (DMSO) solution was investigated as a function of DMSO concentration and at high pressures. A linear relationship was observed for TH (homogeneous ice nucleation temperature) and Tm (melting temperature) for the supercooling of aqueous DMSO solution at normal pressure. Analysis of the DTA (differential thermal analysis) traces for homogeneous ice crystallization in the bottom region of the TH curve for a DMSO solution of R =20 (R: moles of water/moles of DMSO) at high pressures supported the contention that the second critical point (SCP) of liquid water should exist at Pc2=˜200 MPa and at Tc2pressure of SCP, Tc2: temperature of SCP). The presence of two TH peaks for DMSO solutions (R =15, 12, and 10) suggests that phase separation occurs in aqueous DMSO solution (R ≤15) at high pressures and low temperatures (pressure dependence of the two TH curves for DMSO solutions of R =10 and 12 indicates that the two phase-separated components in the DMSO solution of R =10 have different liquid water structures [LDL-like and HDL-like structures (LDL: low-density liquid water, HDL: high-density liquid water)] in the pressure range of 120-230 MPa.

In-cloud multiphase behaviour of acetone in the troposphere: gas uptake, Henry's law equilibrium and aqueous phase photooxidation.

Science.gov (United States)

Poulain, Laurent; Katrib, Yasmine; Isikli, Estelle; Liu, Yao; Wortham, Henri; Mirabel, Philippe; Le Calvé, Stéphane; Monod, Anne

2010-09-01

Acetone is ubiquitous in the troposphere. Several papers have focused in the past on its gas phase reactivity and its impact on tropospheric chemistry. However, acetone is also present in atmospheric water droplets where its behaviour is still relatively unknown. In this work, we present its gas/aqueous phase transfer and its aqueous phase photooxidation. The uptake coefficient of acetone on water droplets was measured between 268 and 281K (γ=0.7 x 10(-2)-1.4 x 10(-2)), using the droplet train technique coupled to a mass spectrometer. The mass accommodation coefficient α (derived from γ) was found in the range (1.0-3.0±0.25) x 10(-2). Henry's law constant of acetone was directly measured between 283 and 298K using a dynamic equilibrium system (H((298K))=(29±5)Matm(-1)), with the Van't Hoff expression lnH(T)=(5100±1100)/T-(13.4±3.9). A recommended value of H was suggested according to comparison with literature. The OH-oxidation of acetone in the aqueous phase was carried out at 298K, under two different pH conditions: at pH=2, and under unbuffered conditions. In both cases, the formation of methylglyoxal, formaldehyde, hydroxyacetone, acetic acid/acetate and formic acid/formate was observed. The formation of small amounts of four hydroperoxides was also detected, and one of them was identified as peroxyacetic acid. A drastic effect of pH was observed on the yields of formaldehyde, one hydroperoxide, and, (to a lesser extent) acetic acid/acetate. Based on the experimental observations, a chemical mechanism of OH-oxidation of acetone in the aqueous phase was proposed and discussed. Atmospheric implications of these findings were finally discussed. Copyright © 2010 Elsevier Ltd. All rights reserved.

An approach for upgrading biomass and pyrolysis product quality using a combination of aqueous phase bio-oil washing and torrefaction pretreatment.

Science.gov (United States)

Chen, Dengyu; Cen, Kehui; Jing, Xichun; Gao, Jinghui; Li, Chen; Ma, Zhongqing

2017-06-01

Bio-oil undergoes phase separation because of poor stability. Practical application of aqueous phase bio-oil is challenging. In this study, a novel approach that combines aqueous phase bio-oil washing and torrefaction pretreatment was used to upgrade the biomass and pyrolysis product quality. The effects of individual and combined pretreatments on cotton stalk pyrolysis were studied using TG-FTIR and a fixed bed reactor. The results showed that the aqueous phase bio-oil washing pretreatment removed metals and resolved the two pyrolysis peaks in the DTG curve. Importantly, it increased the bio-oil yield and improved the pyrolysis product quality. For example, the water and acid content of bio-oil decreased significantly along with an increase in phenol formation, and the heating value of non-condensable gases improved, and these were more pronounced when combined with torrefaction pretreatment. Therefore, the combined pretreatment is a promising method, which would contribute to the development of polygeneration pyrolysis technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Photocathalytic degradation of organic micropollutants in aqueous phase

International Nuclear Information System (INIS)

Driussi, D.

2009-01-01

The aim of this study was to design, construct and test a small system for the photo catalytic degradation of organic micropollutants in aqueous phase using solar radiation. The system is a parabolic linear trough type with automatic one-axis (N-S) tracking of the apparent movement of the sun. The tracking algorithm foresees two dispositions of the collector named horizontal and polar, the last is necessary for installations in locations that are higher than 50 o in latitude. The idea that brought to mind this project was to offer the possibility of treat herbicides polluted waters by means of a simple system without using particular oxidizing chemicals (for example hydrogen peroxide) or components (for example mercury vapour UV lamps) and therefore in an eco-sustainable way. [it

Lignin solubilization and aqueous phase reforming for the production of aromatic chemicals and hydrogen

NARCIS (Netherlands)

Zakzeski, J.|info:eu-repo/dai/nl/326160256; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

2011-01-01

The solubilization and aqueous phase reforming of lignin, including kraft, soda, and alcell lignin along with sugarcane bagasse, at low temperatures (T≤498 K) and pressures (P≤29 bar) is reported for the first time for the production of aromatic chemicals and hydrogen. Analysis of lignin model

Aqueous two-phase (polyethylene glycol + sodium sulfate) system for caffeine extraction: Equilibrium diagrams and partitioning study

International Nuclear Information System (INIS)

Araujo Sampaio, Daniela de; Mafra, Luciana Igarashi; Yamamoto, Carlos Itsuo; Forville de Andrade, Eriel; Oberson de Souza, Michèle; Mafra, Marcos Rogério; Castilhos, Fernanda de

2016-01-01

Highlights: • Binodal curves of PEG (400, 4000 and 6000) + Na_2SO_4 ATPS were determined. • Tie-lines were experimentally determined for aqueous (PEG 400 + Na_2SO_4) system. • Influence of caffeine on LLE of aqueous (PEG 400 + Na_2SO_4) system was investigated. • Partitioning of caffeine in aqueous (PEG 400 + Na_2SO_4) system was investigated. • Caffeine partition showed to be dependent on temperature and TLL. - Abstract: Environmental friendly methods for liquid–liquid extraction have been taken into account due to critical conditions and ecotoxicological effects potentially produced by organic solvents applied in traditional methods. Liquid–liquid extraction using aqueous two phase systems (ATPSs) presents advantages when compared to traditional liquid–liquid extraction. (Polyethylene glycol (PEG) + sodium sulfate + water) ATPS was applied to study partition of caffeine. Binodal curves for ATPSs composed of PEG of different molecular weights (400 g · mol"−"1, 4000 g · mol"−"1 and 6000 g · mol"−"1) sodium sulfate + water were determined by cloud point method at three different temperatures (293.15, 313.15 and 333.15) K. Liquid–liquid equilibrium (LLE) data (tie-lines, slope of the tie-line and tie-lines length) were obtained applying a gravimetric method proposed by Merchuck and co-workers at the same temperatures for aqueous (PEG 400 + sodium sulfate) and aqueous (PEG 400 + sodium sulfate + caffeine) systems. Reliability of the experimental tie-line (TL) data was evaluated using the equations reported by Othmer–Tobias and satisfactory linearity was obtained. Concerning to aqueous (PEG + sodium sulfate) system, the results pointed out that the higher PEG molecular weight the largest is the heterogeneous region. Moreover, temperature showed not to be relevant on binodal curves behavior, but it influenced on tie-line slopes. Partitioning of caffeine in aqueous (PEG 400 + sodium sulfate) system was investigated at different temperatures

DEMONSTRATION BULLETIN: GAS-PHASE CHEMICAL REDUCTION - ECO LOGIC INTERNATIONAL, INC.

Science.gov (United States)

The patented Eco Logic Process employs a gas-phase reduction reaction of hydrogen with organic and chlorinated organic compounds at elevated temperatures to convert aqueous and oily hazardous contaminants into a hydrocarbon-rich gas product. After passing through a scrubber, the ...

Aqueous phase partitioning of hexachlorocyclohexane (HCH) isomers by biosurfactant produced by Pseudomonas aeruginosa WH-2

International Nuclear Information System (INIS)

Sharma, Suman; Singh, Partapbir; Raj, Mayil; Chadha, Bhupinder Singh; Saini, Harvinder Singh

2009-01-01

The different isomers of technical-grade hexachlorocyclohexane (t-HCH) including the insecticidal γ-isomer, commonly known as lindane, have been reported to be toxic, carcinogenic and endocrine disrupters. The spatial arrangements of the chlorine atoms on different isomers and low aqueous phase solubility contribute to their persistence in environment, β-HCH being the most resistance to transformation. The biosurfactant preparation of Pseudomonas aeruginosa isolate WH-2 was evaluated for its ability to improve the aqueous phase partitioning of different isomers of HCH-muck. Further, the ability of biosurfactant preparation to emulsify HCH and n-hexadecane was checked under different conditions, usually characteristic of sites contaminated with pollutants viz. wide range of pH, temperature, and salinity. The data obtained from this study will be helpful in designing suitable bioremediation strategies for huge stock piles of HCH-muck and sites polluted by reckless use/disposal of HCH-isomers.

Improving the treatment of non-aqueous phase TCE in low permeability zones with permanganate

International Nuclear Information System (INIS)

Chokejaroenrat, Chanat; Comfort, Steve; Sakulthaew, Chainarong; Dvorak, Bruce

2014-01-01

Graphical abstract: - Highlights: • Transport experiments used transmissive and low permeability zones (LPZs). • 14 C-labeled TCE was used to quantify oxidation of DNAPL in LPZs by permanganate. • Stabilization aids prevented MnO 2 rind formation. • DNAPL oxidation improved when xanthan and stabilization aids were used. - Abstract: Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO 4 − ) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase 14 C-TCE. The treatments we evaluated included permanganate paired with: (i) a shear-thinning polymer (xanthan); (ii) stabilization aids that minimized MnO 2 rind formation and (iii) a phase-transfer catalyst. In addition, we quantified the ability of these flooding solutions to improve TCE destruction under batch conditions by developing miniature LPZ cylinders that were spiked with 14 C-TCE. Transport experiments showed that MnO 4 − alone was inefficient in penetrating the LPZ and reacting with non-aqueous phase TCE, due to a distinct and large MnO 2 rind that inhibited the TCE from further oxidant contact. By including xanthan with MnO 4 − , the sweeping efficiency increased (90%) but rind formation was still evident. By including the stabilization aid, sodium hexametaphosphate (SHMP) with xanthan, permanganate penetrated 100% of the LPZ, no rind was observed, and the percentage of TCE oxidized increased. Batch experiments using LPZ cylinders allowed longer contact times between the flooding solutions and the DNAPL and results showed that SHMP + MnO 4 − improved TCE destruction by ∼16% over MnO 4 − alone (56.5% vs. 40.1%). These results support

Shear-Induced Phase Separation in Aqueous Polymer Solutions: Temperature-Sensitive Microgels and Linear Polymer Chains

NARCIS (Netherlands)

Stieger, M.A.; Richtering, W.

2003-01-01

The influence of shear flow on the phase separation of aqueous poly(N-isopropylacrylamide) (PNiPAM) microgel suspensions was investigated by means of rheo-turbidity and rheo-small angle neutron scattering (rheo-SANS) and compared to the behavior of linear PNiPAM macromolecules. The rheological

Chitosan-coated magnetic nanoparticles prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion.

Science.gov (United States)

Pineda, María Guadalupe; Torres, Silvia; López, Luis Valencia; Enríquez-Medrano, Francisco Javier; de León, Ramón Díaz; Fernández, Salvador; Saade, Hened; López, Raúl Guillermo

2014-07-02

Chitosan-coated magnetic nanoparticles (CMNP) were prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion in the presence of chitosan. The high-aqueous phase concentration led to productivities close to 0.49 g CMNP/100 g microemulsion; much higher than those characteristic of precipitation in reverse microemulsions for preparing magnetic nanoparticles. The obtained nanoparticles present a narrow particle size distribution with an average diameter of 4.5 nm; appearing to be formed of a single crystallite; furthermore they present superparamagnetism and high magnetization values; close to 49 emu/g. Characterization of CMNP suggests that chitosan is present as a non-homogeneous very thin layer; which explains the slight reduction in the magnetization value of CMNP in comparison with that of uncoated magnetic nanoparticles. The prepared nanoparticles show high heavy ion removal capability; as demonstrated by their use in the treatment of Pb2+ aqueous solutions; from which lead ions were completely removed within 10 min.

Chitosan-Coated Magnetic Nanoparticles Prepared in One-Step by Precipitation in a High-Aqueous Phase Content Reverse Microemulsion

Directory of Open Access Journals (Sweden)

María Guadalupe Pineda

2014-07-01

Full Text Available Chitosan-coated magnetic nanoparticles (CMNP were prepared in one-step by precipitation in a high-aqueous phase content reverse microemulsion in the presence of chitosan. The high-aqueous phase concentration led to productivities close to 0.49 g CMNP/100 g microemulsion; much higher than those characteristic of precipitation in reverse microemulsions for preparing magnetic nanoparticles. The obtained nanoparticles present a narrow particle size distribution with an average diameter of 4.5 nm; appearing to be formed of a single crystallite; furthermore they present superparamagnetism and high magnetization values; close to 49 emu/g. Characterization of CMNP suggests that chitosan is present as a non-homogeneous very thin layer; which explains the slight reduction in the magnetization value of CMNP in comparison with that of uncoated magnetic nanoparticles. The prepared nanoparticles show high heavy ion removal capability; as demonstrated by their use in the treatment of Pb2+ aqueous solutions; from which lead ions were completely removed within 10 min.

Dynamic speciation analysis of atrazine in aqueous latex nanoparticle dispersions using solid phase microextraction (SPME)

NARCIS (Netherlands)

Benhabib, K.; Town, R.M.; Leeuwen, van H.P.

2009-01-01

Solid phase microextraction (SPME) is applied in the dynamic speciation analysis of the pesticide atrazine in an aqueous medium containing sorbing latex nanoparticles. It is found that the overall rate of extraction of the analyte is faster than in the absence of nanoparticles and governed by the

Heteroaggregation of graphene oxide with minerals in aqueous phase.

Science.gov (United States)

Zhao, Jian; Liu, Feifei; Wang, Zhenyu; Cao, Xuesong; Xing, Baoshan

2015-03-03

Upon release into waters, sediments, and soils, graphene oxide (GO) may interact with fine mineral particles. We investigated the heteroaggregation of GO with different minerals, including montmorillonite, kaolinite, and goethite, in aqueous phase. GO significantly enhanced the dispersion of positively charged goethite (>50%) via heteroaggregation, while there was no interaction between GO and negatively charged montmorillonite or kaolinite. Electrostatic attraction was the dominant force in the GO-goethite heteroaggregation (pH 4.0-8.5), and the dissolved Fe ions (formation of multilayered GO-goethite complex with high configurational stability. These findings are useful for understanding the interaction of GO with mineral surfaces, and potential fate and toxicity of GO under natural conditions in aquatic environments, as well as in soils and sediments.

Mechanisms of catalytic cleavage of benzyl phenyl ether in aqueous and apolar phases

Energy Technology Data Exchange (ETDEWEB)

He, Jiayue; Lu, Lu; Zhao, Chen; Mei, Donghai; Lercher, Johannes A.

2014-03-01

Catalytic pathways for the cleavage of ether bonds in benzyl phenyl ether (BPE) in liquid phase using Ni- and zeolite-based catalysts are explored. In the absence of catalysts, the C-O bond is selectively cleaved in water by hydrolysis, forming phenol and benzyl alcohol as intermediates, followed by alkylation. The hydronium ions catalyzing the reactions are provided by the dissociation of water at 523 K. Upon addition of HZSM-5, rates of hydrolysis and alkylation are markedly increased in relation to proton concentrations. In the presence of Ni/SiO₂, the selective hydrogenolysis dominates for cleaving the C_aliphatic-O bond. Catalyzed by the dual-functional Ni/HZSM-5, hydrogenolysis occurs as the major route rather than hydrolysis (minor route). In apolar undecane, the non-catalytic thermal pyrolysis route dominates. Hydrogenolysis of BPE appears to be the major reaction pathway in undecane in the presence of Ni/SiO₂ or Ni/HZSM-5, almost completely suppressing radical reactions. Density functional theory (DFT) calculations strongly support the proposed C-O bond cleavage mechanisms on BPE in aqueous and apolar phases. These calculations show that BPE is initially protonated and subsequently hydrolyzed in the aqueous phase. Finally, DFT calculations suggest that the radical reactions in non-polar solvents lead to primary benzyl and phenoxy radicals in undecane, which leads to heavier condensation products as long as metals are absent for providing dissociated hydrogen.

Mass transfer coefficient of slug flow for organic solvent-aqueous system in a microreactor

Energy Technology Data Exchange (ETDEWEB)

Tuek, Ana Jurinjak; Anic, Iva; Kurtanjek, Zelimir; Zelic, Bruno [University of Zagreb, Zagreb (Croatia)

2015-06-15

Application of microreactor systems could be the next break-through in the intensification of chemical and biochemical processes. The common flow regime for organic solvent-aqueous phase two-phase systems is a segmented flow. Internal circulations in segments cause high mass transfer and conversion. We analyzed slug flow in seven systems of organic solvents and aqueous phase. To analyze how slug lengths in tested systems depend on linear velocity and physical and chemical properties of used organic solvents, regression models were proposed. It was shown that models based on linearization of approximation by potentials give low correlation for slug length prediction; however, application of an essential nonlinear model of multiple layer perception (MLP) neural network gives high correlation with R{sup 2}=0.9. General sensitivity analysis was applied for the MLP neural network model, which showed that 80% of variance in slug length for the both phases is accounted for the viscosity and density of the organic phases; 10% is accounted by surface tension of the organic phase, while molecular masses and flow rates each account for 5%. For defined geometry of microreactor, mass transfer has been determined by carrying out the neutralization experiment with NaOH where acetic acid diffuses from organic phase (hexane) into aqueous phase. Estimated mass transfer coefficients were in the range k{sub L}a=4,652-1,9807 h{sup -1}.

Mass transfer coefficient of slug flow for organic solvent-aqueous system in a microreactor

International Nuclear Information System (INIS)

Tuek, Ana Jurinjak; Anic, Iva; Kurtanjek, Zelimir; Zelic, Bruno

2015-01-01

Application of microreactor systems could be the next break-through in the intensification of chemical and biochemical processes. The common flow regime for organic solvent-aqueous phase two-phase systems is a segmented flow. Internal circulations in segments cause high mass transfer and conversion. We analyzed slug flow in seven systems of organic solvents and aqueous phase. To analyze how slug lengths in tested systems depend on linear velocity and physical and chemical properties of used organic solvents, regression models were proposed. It was shown that models based on linearization of approximation by potentials give low correlation for slug length prediction; however, application of an essential nonlinear model of multiple layer perception (MLP) neural network gives high correlation with R 2 =0.9. General sensitivity analysis was applied for the MLP neural network model, which showed that 80% of variance in slug length for the both phases is accounted for the viscosity and density of the organic phases; 10% is accounted by surface tension of the organic phase, while molecular masses and flow rates each account for 5%. For defined geometry of microreactor, mass transfer has been determined by carrying out the neutralization experiment with NaOH where acetic acid diffuses from organic phase (hexane) into aqueous phase. Estimated mass transfer coefficients were in the range k L a=4,652-1,9807 h -1

Comparison of colorimetric m ethods for the quantification of model proteins in aqueous two-phase systems

OpenAIRE

Glyk, Anna; Heinisch, Sandra L.; Scheper, Thomas; Beutel, Sascha

2015-01-01

In the current study, the quantification of different model proteins in the presence of typical aqueous two-phase system components was investigated by using the Bradford and bicinchoninic acid (BCA) assays. Each phase-forming component above 1 and 5 wt% had considerable effects on the protein quantification in both assays, respectively, resulting in diminished protein recoveries/absorption values by increasing poly(ethylene glycol) (PEG)/salt concentration and PEG molecular weight. Therefore...

Chelate-Modified Fenton Reaction for the Degradation of Trichloroethylene in Aqueous and Two-Phase Systems

Energy Technology Data Exchange (ETDEWEB)

Lewis, Scott [Univ of KY, dept of chemical and materials engineering; lynch, Andrew [Univ of KY, dept of chemical and materials engineering; Bachas, Leonidas [Univ of KY, Dept of Chemistry; hampson, Steve [Univ of KY Center for Applied Energy Research - KY Research Consortium of Energy and Environment; Ormsbee, Lindelle [Univ of KY Center for Applied Energy Research - KY Research Consortium of Energy and Environment; Bhattacharyya, Dibakar [Univ of KY, dept of chemical and materials engineering

2008-06-01

The Standard Fenton reaction has been used for In-Situ Chemical Oxidation (ISCO) of toxic organics in groundwater. However, it requires low pH operating conditions, and thus has limitations for in situ applications. In addition, hydroxyl radicals are rapidly consumed by hydroxyl scavengers found in the subsurface. These problems are alleviated through the chelate-modified Fenton (hydroxyl radical) reaction, which includes the addition of nontoxic chelate (L) such as citrate or gluconic acid. This chelate allows the reaction to take place at bear neutral pH and control hydrogen peroxide consumption by binding to Fe(II), forming an FeL complex. The chelate also binds to Fe(III), preventing its precipitation as ferric hydroxide and thus prevents problems associated with injection well plugging. The rate of TCE dechlorination in chelate-modified Fenton systems is a function of pH, H2O2 concentration, and FE:L ratio. The primary objective of this research is to model and apply this process to the destruction of trichloroethylene (TCE) present in both the aqueous and organic (in the form of droplets) phases. Experimentation proved the chelate-modified Fenton reaction effectively dechlorinates TCE in both the aqueous and organic phases at near-neutral pH. Other focuses of this work include determining the effect of [L]:[Fe] ratios on H2O2 and TCE degradation as well as reusability of the FE citrate solution under repeated H2O2 injections. Generalized models were developed to predict the concentration of TCE in the aqueous phase and TCE droplet radius as a function of time using established hydroxyl radial kinetics and mass transfer relationships.

Temperature-induced phase transition in aqueous solutions of poly(N-isopropylacrylamide)-based block copolymer

Czech Academy of Sciences Publication Activity Database

Spěváček, Jiří; Konefal, Rafal; Dybal, Jiří

2016-01-01

Roč. 369, č. 1 (2016), s. 92-96 ISSN 1022-1360. [International IUPAC Conference on Polymer-Solvent Complexes and Intercalates /11./ - POLYSOLVAT-11. Kolkata, 27.01.2016-30.01.2016] R&D Projects: GA ČR(CZ) GA15-13853S Institutional support: RVO:61389013 Keywords : aqueous solutions * block copolymers * micelles Subject RIV: CD - Macromolecular Chemistry

A Simple Approach to Characterize Gas-Aqueous Liquid Two-phase Flow Configuration Based on Discrete Solid-Liquid Contact Electrification.

Science.gov (United States)

Choi, Dongwhi; Lee, Donghyeon; Kim, Dong Sung

2015-10-14

In this study, we first suggest a simple approach to characterize configuration of gas-aqueous liquid two-phase flow based on discrete solid-liquid contact electrification, which is a newly defined concept as a sequential process of solid-liquid contact and successive detachment of the contact liquid from the solid surface. This approach exhibits several advantages such as simple operation, precise measurement, and cost-effectiveness. By using electric potential that is spontaneously generated by discrete solid-liquid contact electrification, the configurations of the gas-aqueous liquid two-phase flow such as size of a gas slug and flow rate are precisely characterized. According to the experimental and numerical analyses on parameters that affect electric potential, gas slugs have been verified to behave similarly to point electric charges when the measuring point of the electric potential is far enough from the gas slug. In addition, the configuration of the gas-aqueous liquid two-phase microfluidic system with multiple gas slugs is also characterized by using the presented approach. For a proof-of-concept demonstration of using the proposed approach in a self-triggered sensor, a gas slug detector with a counter system is developed to show its practicality and applicability.

Interactions in the aqueous phase and adsorption at the air-water interface of caseinoglycomacropeptide (GMP) and beta-lactoglobulin mixed systems.

Science.gov (United States)

Martinez, María J; Sánchez, Cecilio Carrera; Patino, Juan M Rodríguez; Pilosof, Ana M R

2009-01-01

The aim of this work was to study the interactions and adsorption of caseinoglycomacropeptide (GMP) and GMP:beta-lactoglobulin (beta-lg) mixed system in the aqueous phase and at the air-water interface. The existence of associative interactions between GMP and beta-lg in the aqueous phase was investigated by dynamic light scattering, differential scanning calorimetry (DSC), fluorometry and native PAGE-electrophoresis. The surface pressure isotherm and the static and dynamic surface pressure were determined by tensiometry and surface dilatational properties. The results showed that GMP presented higher surface activity than beta-lg at a concentration of 4%wt but beta-lg showed higher film forming ability. In the mixed systems beta-lg dominated the static and dynamic surface pressure and the rheological properties of interfacial films suggesting that beta-lg hinders GMP adsorption because, in simple competition, GMP should dominate because of its higher surface activity. The surface predominance of beta-lg can be attributed to binding of GMP to beta-lg in the aqueous phase that prevents GMP adsorption on its own.

Aqueous-phase photochemical oxidation and direct photolysis of vanillin - a model compound of methoxy phenols from biomass burning

Science.gov (United States)

Li, Y. J.; Huang, D. D.; Cheung, H. Y.; Lee, A. K. Y.; Chan, C. K.

2014-03-01

We present here experimental results on aqueous-phase (A) photochemical oxidation (with UV and OH radicals generated from H2O2 photolysis) and (B) direct photolysis (with only UV irradiation) of a methoxy phenol, vanillin (VL), as a model compound from biomass burning. Both on-line aerosol mass spectrometric (AMS) characterization and off-line chemical analyses were performed. AMS analyses of dried atomized droplets of the bulk reacting mixtures showed that VL almost entirely evaporates during the drying process. Large amounts of organic mass remained in the particle phase after reactions under both conditions. Under condition (A), AMS measured organic mass first increased rapidly and then decreased, attributable to the formation of non-volatile products and subsequent formation of smaller and volatile products, respectively. The oxygen-to-carbon (O : C) ratio of the products reached 1.5 after about 80 min, but dropped substantially thereafter. In contrast, organic mass increased slowly under condition (B). The O : C ratio reached 1.0 after 180 min. In off-line analyses, small oxygenates were detected under condition (A), while hydroxylated products and dimers of VL were detected under condition (B). Particle hygroscopic growth factor (GF) and cloud condensation nuclei (CCN) activity of the reacting mixtures were found to depend on both organic volume fraction and the degree of oxygenation of organics. Results show that (1) aqueous-phase processes can lead to the retention of a large portion of the organic mass in the particle phase; (2) once retained, this portion of organic mass significantly changes the hygroscopicity and CCN activity of the aerosol particles; (3) intensive photochemical oxidation gave rise to an O : C ratio as high as 1.5 but the ratio decreased as further oxidation led to smaller and more volatile products; and (4) polymerization occurred with direct photolysis, resulting in high-molecular-weight products of a yellowish color. This study

Aqueous-phase photochemical oxidation and direct photolysis of vanillin - a model compound of methoxy-phenols from biomass burning

Science.gov (United States)

Li, Y. J.; Huang, D. D.; Cheung, H. Y.; Lee, A. K. Y.; Chan, C. K.

2013-10-01

We present here experimental results on aqueous-phase (A) photochemical oxidation (with UV and OH radicals generated from H2O2 photolysis) and (B) direct photolysis (with only UV irradiation) of a methoxy-phenol, vanillin (VL), as a model compound from biomass burning. Both on-line aerosol mass spectrometric (AMS) characterization and off-line chemical analyses were performed. AMS analyses of dried atomized droplets of the bulk reacting mixtures showed that VL almost entirely evaporates during the drying process. Large amounts of organic mass remained in the particle phase after reactions under both conditions. Under condition (A), AMS measured organic mass first increased rapidly and then decreased, attributable to the formation of non-volatile products and subsequent formation of smaller and volatile products, respectively. The oxygen-to-carbon (O:C) ratio of the products reached 1.5 after about 80 min, but dropped substantially thereafter. In contrast, organic mass increased slowly under condition (B). The O:C ratio reached 1.0 after 180 min. In off-line analyses, small oxygenates were detected under condition (A), while hydroxylated products and dimers of VL were detected under condition (B). Particle hygroscopic growth factor (GF) and cloud condensation nuclei (CCN) activity of the reacting mixtures were found to be dependent on both organic volume fraction and the degree of oxygenation of organics. Results show that (1) aqueous-phase processes can lead to the retention of a large portion of the organic mass in the particle phase; (2) once retained, this portion of organic mass significantly changes the hygroscopicity and CCN activity of the aerosol particles; (3) intensive photochemical oxidation gave rise to an O:C ratio as high as 1.5 but the ratio decreased as further oxidation led to smaller and more volatile products; and (4) polymerization occurred with direct photolysis, resulting in high-molecular-weight products of a yellowish color. This study

Influence of aqueous phase on electrochemical biocorrosion tests in diesel/water systems

Energy Technology Data Exchange (ETDEWEB)

Bento, F.M. [Dept. of Soils, Faculty of Agronomy, UFRGS, 7712 Bento Goncalves Avenue, CEP: 91540-001, POA, RS (Brazil); Englert, G.E.; Muller, I.L. [Dept. of Metallurgy, Biocorrosion and Biofilms Lab, UFRGS, 99 Osvaldo Aranha Avenue s.615D, CEP: 90035-190, POA, RS (Brazil); Gaylarde, C.C. [Dept. of Biophisics, UFRGS POA, RS (Brazil)

2004-08-01

Storage tanks containing microbially contaminated diesel oil are susceptible to corrosion. This process may be evaluated electrochemically in the laboratory using simulated storage systems containing diesel oil and an aqueous phase. The simulated aqueous phase must supply mineral nutrients for microbial growth, together with adequate electrical conductivity, without, however, being too corrosive, so as to allow the aggressive nature of the microbial metabolites to be detected. In this investigation, microbial growth was measured in six electrically conductive media overlaid with metropolitan diesel oil containing an additive package. The microorganisms were the filamentous fungi, Hormoconis resinae, Paecilomyces variotii and Aspergillus fumigatus, the bacterium Bacillus subtilis and the yeast Candida silvicola, all previously isolated from contaminated diesel oil. After 60 days incubation with pure or mixed inocula of these microorganisms, pH, conductivity and viable microorganisms were measured. The electrochemical behaviour of carbon steel ASTM 283-93-C was determined in each of the six media (uninoculated) and in selected inoculated medium via measurements of open circuit potential and potentiostatic polarization curves. The uptake of phosphate (corrosion inhibitor), microbial growth, pH, conductivity and anodic and cathodic polarization curves were assessed in the water phase after 30 and 60 days of incubation with each single species Aspergillus fumigatus and Hormoconis resinae and with the consortium. The medium which proved most appropriate was Bushnell-Haas medium modified by the omission of chlorides, which allowed satisfactory microbial growth and had low aggressivity towards the steel. The performance of electrochemical tests in aerated, rather than deaerated, electrolyte solutions is suggested to be important to allow the detection of microbial influence on passive film formation and stability. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

Derivatisation/solid-phase microextraction followed by gas chromatography-mass spectrometry for the analysis of phenoxy acid herbicides in aqueous samples

DEFF Research Database (Denmark)

Nilsson, Torben; Baglio, Daniela; Galdo-Miguez, Isabel

1998-01-01

Different combinations of derivatisation and solid-phase microextraction followed by gas chromatography-mass spectrometry were optimised and evaluated for the analysis of phenoxy acid herbicides in water. The most successful derivatisation approach was aqueous-phase derivatisation with benzyl...

Comment on the internal consistency of thermodynamic databases supporting repository safety assessments

International Nuclear Information System (INIS)

Arthur, R.C.

2001-11-01

This report addresses the concept of internal consistency and its relevance to the reliability of thermodynamic databases used in repository safety assessments. In addition to being internally consistent, a reliable database should be accurate over a range of relevant temperatures and pressures, complete in the sense that all important aqueous species, gases and solid phases are represented, and traceable to original experimental results. No single definition of internal consistency need to be universally accepted as the most appropriate under all conditions, however. As a result, two databases that are each internally consistent may be inconsistent with respect to each other, and a database derived from two or more such databases must itself be internally inconsistent. The consequences of alternative definitions that are reasonably attributable to the concept of internal consistency can be illustrated with reference to the thermodynamic database supporting SKB's recent SR 97 safety assessment. This database is internally inconsistent because it includes equilibrium constants calculated over a range of temperatures: using conflicting reference values for some solids, gases and aqueous species that are common to two internally consistent databases (the OECD/NEA database for radioelements and SUPCRT databases for non-radioactive elements) that serve as source databases for the SR 97 TDB, using different definitions in these source databases of standard states for condensed phases and aqueous species, based on different mathematical expressions used in these source databases representing the temperature dependence of the heat capacity, and based on different chemical models adopted in these source databases for the aqueous phase. The importance of such inconsistencies must be considered in relation to the other database reliability criteria noted above, however. Thus, accepting a certain level of internal inconsistency in a database it is probably preferable to use a

Comment on the internal consistency of thermodynamic databases supporting repository safety assessments

Energy Technology Data Exchange (ETDEWEB)

Arthur, R.C. [Monitor Scientific, LLC, Denver, CO (United States)

2001-11-01

This report addresses the concept of internal consistency and its relevance to the reliability of thermodynamic databases used in repository safety assessments. In addition to being internally consistent, a reliable database should be accurate over a range of relevant temperatures and pressures, complete in the sense that all important aqueous species, gases and solid phases are represented, and traceable to original experimental results. No single definition of internal consistency need to be universally accepted as the most appropriate under all conditions, however. As a result, two databases that are each internally consistent may be inconsistent with respect to each other, and a database derived from two or more such databases must itself be internally inconsistent. The consequences of alternative definitions that are reasonably attributable to the concept of internal consistency can be illustrated with reference to the thermodynamic database supporting SKB's recent SR 97 safety assessment. This database is internally inconsistent because it includes equilibrium constants calculated over a range of temperatures: using conflicting reference values for some solids, gases and aqueous species that are common to two internally consistent databases (the OECD/NEA database for radioelements and SUPCRT databases for non-radioactive elements) that serve as source databases for the SR 97 TDB, using different definitions in these source databases of standard states for condensed phases and aqueous species, based on different mathematical expressions used in these source databases representing the temperature dependence of the heat capacity, and based on different chemical models adopted in these source databases for the aqueous phase. The importance of such inconsistencies must be considered in relation to the other database reliability criteria noted above, however. Thus, accepting a certain level of internal inconsistency in a database it is probably preferable to

Improving the treatment of non-aqueous phase TCE in low permeability zones with permanganate

Energy Technology Data Exchange (ETDEWEB)

Chokejaroenrat, Chanat, E-mail: chanat@sut.ac.th [Department of Civil Engineering, University of Nebraska, Lincoln, NE 68588-0531 (United States); School of Environmental Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Comfort, Steve, E-mail: scomfort1@unl.edu [School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915 (United States); Sakulthaew, Chainarong, E-mail: cvtcns@ku.ac.th [School of Natural Resources, University of Nebraska, Lincoln, NE 68583-0915 (United States); Department of Veterinary Technology, Kasetsart University, Bangkok 10900 (Thailand); Dvorak, Bruce, E-mail: bdvorak1@unl.edu [Department of Civil Engineering, University of Nebraska, Lincoln, NE 68588-0531 (United States)

2014-03-01

Graphical abstract: - Highlights: • Transport experiments used transmissive and low permeability zones (LPZs). • {sup 14}C-labeled TCE was used to quantify oxidation of DNAPL in LPZs by permanganate. • Stabilization aids prevented MnO{sub 2} rind formation. • DNAPL oxidation improved when xanthan and stabilization aids were used. - Abstract: Treating dense non-aqueous phase liquids (DNAPLs) embedded in low permeability zones (LPZs) is a particularly challenging issue for injection-based remedial treatments. Our objective was to improve the sweeping efficiency of permanganate (MnO{sub 4}{sup −}) into LPZs to treat high concentrations of TCE. This was accomplished by conducting transport experiments that quantified the penetration of various permanganate flooding solutions into a LPZ that was spiked with non-aqueous phase {sup 14}C-TCE. The treatments we evaluated included permanganate paired with: (i) a shear-thinning polymer (xanthan); (ii) stabilization aids that minimized MnO{sub 2} rind formation and (iii) a phase-transfer catalyst. In addition, we quantified the ability of these flooding solutions to improve TCE destruction under batch conditions by developing miniature LPZ cylinders that were spiked with {sup 14}C-TCE. Transport experiments showed that MnO{sub 4}{sup −} alone was inefficient in penetrating the LPZ and reacting with non-aqueous phase TCE, due to a distinct and large MnO{sub 2} rind that inhibited the TCE from further oxidant contact. By including xanthan with MnO{sub 4}{sup −}, the sweeping efficiency increased (90%) but rind formation was still evident. By including the stabilization aid, sodium hexametaphosphate (SHMP) with xanthan, permanganate penetrated 100% of the LPZ, no rind was observed, and the percentage of TCE oxidized increased. Batch experiments using LPZ cylinders allowed longer contact times between the flooding solutions and the DNAPL and results showed that SHMP + MnO{sub 4}{sup −} improved TCE destruction by �

Mars Aqueous Processing System, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The Mars Aqueous Processing System (MAPS) is a novel technology for recovering oxygen, iron, and other constituents from lunar and Mars soils. The closed-loop...

Enhancing the lateral-flow immunoassay for detection of proteins using an aqueous two-phase micellar system.

Science.gov (United States)

Mashayekhi, Foad; Le, Alexander M; Nafisi, Parsa M; Wu, Benjamin M; Kamei, Daniel T

2012-10-01

The lateral-flow (immuno)assay (LFA) has been widely investigated for the detection of molecular, macromolecular, and particle targets at the point-of-need due to its ease of use, rapid processing, and minimal power and laboratory equipment requirements. However, for some analytes, such as certain proteins, the detection limit of LFA is inferior to lab-based assays, such as the enzyme-linked immunosorbent assay, and needs to be improved. One solution for improving the detection limit of LFA is to concentrate the target protein in a solution prior to the detection step. In this study, a novel approach was used in the context of an aqueous two-phase micellar system comprised of the nonionic surfactant Triton X-114 to concentrate a model protein, namely transferrin, prior to LFA. Proteins have been shown to partition, or distribute, fairly evenly between the two phases of an aqueous two-phase system, which in turn results in their limited concentration in one of the two phases. Therefore, larger colloidal gold particles decorated with antibodies for transferrin were used in the concentration step to bind to transferrin and aid its partitioning into the top, micelle-poor phase. By manipulating the volume ratio of the two coexisting micellar phases and combining the concentration step with LFA, the transferrin detection limit of LFA was improved by tenfold from 0.5 to 0.05 μg/mL in a predictive manner. In addition to enhancing the sensitivity of LFA, this universal concentration method could also be used to improve other detection assays.

Effects of aggregation on the excitation dynamics of LH2 from Thermochromatium tepidum in aqueous phase and in chromatophores.

Science.gov (United States)

Yang, Fan; Yu, Long-Jiang; Wang, Peng; Ai, Xi-Cheng; Wang, Zheng-Yu; Zhang, Jian-Ping

2011-06-23

We carried out femtosecond magic-angle and polarized pump-probe spectroscopies for the light-harvesting complex 2 (LH2) from Thermochromatium (Tch.) tepidum in aqueous phase and in chromatophores. To examine the effects of LH2 aggregation on the dynamics of excitation energy transfer, dominant monodispersed and aggregated LH2s were prepared by controlling the surfactant concentrations. The aqueous preparations solubilized with different concentrations of n-dodecyl-β-D-maltoside (DDM) show similar visible-to-near-infrared absorption spectra, but distinctively different aggregation states, as revealed by using dynamic light scattering. The B800 → B850 intra-LH2 energy transfer time was determined to be 1.3 ps for isolated LH2, which, upon aggregation in aqueous phase or clustering in chromatophores, shortened to 1.1 or 0.9 ps, respectively. The light-harvesting complex 1 (LH1) of this thermophilic purple sulfur bacterium contains bacteriochlorophyll a absorbing at 915 nm (B915), and the LH2(B850) → LH1(B915) intercomplex transfer time in chromatophores was found to be 6.6 ps. For chromatophores, a depolarization time of 21 ps was derived from the anisotropy kinetics of B850*, which is attributed to the migration of B850* excitation before being trapped by LH1. In addition, the B850* annihilation is accelerated upon LH2 aggregation in aqueous phase, but it is much less severe upon LH2 clustering in the intracytoplasmic membrane. These results are helpful in understanding the light-harvesting function of a bacterial photosynthetic membrane incorporating different types of antenna complexes.

The salting-out effect and phase separation in aqueous solutions of tri-sodium citrate and 1-butyl-3-methylimidazolium bromide

International Nuclear Information System (INIS)

Sadeghi, Rahmat; Golabiazar, Roonak; Shekaari, Hemayat

2010-01-01

The aim of this work is to obtain further evidence about the salting-out effect produced by the addition of tri-sodium citrate to aqueous solutions of water miscible ionic liquid 1-butyl-3-methylimidazolium bromide ([C 4 mim][Br]) by evaluating the effect of tri-sodium citrate on the thermodynamic properties of aqueous solutions of this ionic liquid. Experimental measurements of density and sound velocity at different temperatures ranging from (288.15 to 308.15) K, the refractive index at 308.15 K and the liquid-liquid phase diagram at different temperatures ranging from (288.15 to 338.15) K for aqueous solutions containing 1-butyl-3-methylimidazolium bromide ([C 4 mim][Br]) and tri-sodium citrate (Na 3 Cit) are taken. The apparent molar volume of transfer of [C 4 mim][Br] from water to aqueous solutions of Na 3 Cit have positive values and it increases by increasing salt molality. Although at high IL molality, the apparent molar isentropic compressibility shows similar behaviour with that of the apparent molar volume. However at low concentrations of IL, the apparent molar isentropic compressibility of transfer of [C 4 mim][Br] from water to aqueous solutions of Na 3 Cit have negative values. The effects of temperature and the addition of Na 3 Cit and [C 4 mim][Br] on the liquid-liquid phase diagram of the investigated system have been studied. It was found that an increase in temperature caused the expansion of the one-phase region. The presence of Na 3 Cit triggers a salting-out effect, leading to significant upward shifts of the liquid-liquid de-mixing temperatures of the system. The effect of temperature on the phase-forming ability in the system investigated has been studied based on a salting-out coefficient obtained from fitting the binodal values to a Setschenow-type equation for each temperature. Based on cloud point values, the energetics of the clouding process have been estimated and it was found that both of entropy and enthalpy are the driving forces

Highly selective bimetallic Pt-Cu/Mg(Al)O catalysts for the aqueous-phase reforming of glycerol

NARCIS (Netherlands)

Boga, D.A.; Oord, R.; Beale, A.M.; Chung, Y.M.; Bruijnincx, P.C.A.; Weckhuysen, B.M.

2013-01-01

Monometallic Pt and bimetallic Pt-Cu catalysts supported on Mg(Al)O mixed oxides, obtained by calcination of the corresponding layered double hydroxides (LDHs), were prepared and tested in the aqueous-phase reforming (APR) of glycerol. The effect of the Mg/Al ratio and calcination temperature of the

Advanced Aqueous Phase Catalyst Development using Combinatorial Methods, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Combinatorial methods are proposed to develop advanced Aqueous Oxidation Catalysts (AOCs) with the capability to mineralize organic contaminants present in effluents...

Influence of the composition of the aqueous phase on the behavior of the system FeCl3-HCl-DPE

International Nuclear Information System (INIS)

Ramirez, F. de M.; Jimenez-Reyes, M.

1981-07-01

We studied the influence of the aqueous phase composition upon an extraction system in which, at room temperature (20 0 C +- 3 0 C) using the dissolvents FeCl 3 -HCl-di-isopropyl ether the third phase phenomena is present after one minute of agitation. Our results showed that principally the hydrochloric acid dissolvent produced each of the three phases at given concentration levels as well as determined the nature of the chemical composition in each phase. (author)

Molar mass fractionation in aqueous two-phase polymer solutions of dextran and poly(ethylene glycol).

Science.gov (United States)

Zhao, Ziliang; Li, Qi; Ji, Xiangling; Dimova, Rumiana; Lipowsky, Reinhard; Liu, Yonggang

2016-06-24

Dextran and poly(ethylene glycol) (PEG) in phase separated aqueous two-phase systems (ATPSs) of these two polymers, with a broad molar mass distribution for dextran and a narrow molar mass distribution for PEG, were separated and quantified by gel permeation chromatography (GPC). Tie lines constructed by GPC method are in excellent agreement with those established by the previously reported approach based on density measurements of the phases. The fractionation of dextran during phase separation of ATPS leads to the redistribution of dextran of different chain lengths between the two phases. The degree of fractionation for dextran decays exponentially as a function of chain length. The average separation parameters, for both dextran and PEG, show a crossover from mean field behavior to Ising model behavior, as the critical point is approached. Copyright © 2016 Elsevier B.V. All rights reserved.

Separation and Enrichment of Lectin from Zihua Snap-Bean (Phaseolus vulgaris Seeds by PEG 600–Ammonium Sulfate Aqueous Two-Phase System

Directory of Open Access Journals (Sweden)

Bin Jiang

2017-09-01

Full Text Available A fast and efficient method based on a polyethylene glycol (PEG 600/(NH42SO4 aqueous two-phase system for extracting lectin from Zihua snap-bean (Phaseolus vulgaris seeds was established. According to a Box–Behnken design (BBD, involving four factors at three levels each subjected to analysis of variance (ANOVA and response surface analysis, the protein recovery and the purification factor of lectin in the top phase were used as the response values of the variance analysis to acquire the multivariate quadratic regression model. SDS–PAGE electrophoresis and the hemagglutination test were used to detect the distribution of lectin in the aqueous two-phase system (ATPS. The obtained data indicated that lectin was preferentially partitioned into the PEG-rich phase, and the ATPS, composed of 15% (NH42SO4 (w/w, 18% PEG 600 (w/w, 0.4 g/5 g NaCl and 1 mL crude extract, showed good selectivity for lectin when the pH value was 7.5. Under the optimal conditions, most of the lectin was assigned to the top phase in the ATPS, and the hemagglutination activity of the purified lectin in the top phase was 3.08 times that of the crude extract. Consequently, the PEG 600/(NH42SO4 aqueous two-phase system was an effective method for separating and enriching lectin directly from the crude extract of Zihua snap-bean seeds.

Effects of solid/liquid phase fractionation on pH and aqueous species molality in subduction zone fluids

Science.gov (United States)

Zhong, X.; Galvez, M. E.

2017-12-01

Metamorphic fluids are a crucial ingredient of geodynamic evolution, i.e. heat transfer, rock mechanics and metamorphic/metasomatic reactions. During crustal evolution at elevated P and T, rock forming components can be effectively fractionated from the reactive rock system by at least two processes: 1. extraction from porous rocks by liquid phases such as solute-bearing (e.g. Na+, Mg2+) aqueous fluids or partial melts. 2. isolation from effective bulk rock composition due to slow intragranular diffusion in high-P refractory phases such as garnet. The effect of phase fractionation (garnet, partial melt and aqueous species) on fluid - rock composition and properties remain unclear, mainly due to a high demand in quantitative computations of the thermodynamic interactions between rocks and fluids over a wide P-T range. To investigate this problem, we build our work on an approach initially introduced by Galvez et al., (2015) with new functionalities added in a MATLAB code (Rubisco). The fluxes of fractionated components in fluid, melt and garnet are monitored along a typical prograde P-T path for a model crustal pelite. Some preliminary results suggest a marginal effect of fractionated aqueous species on fluid and rock properties (e.g. pH, composition), but the corresponding fluxes are significant in the context of mantle wedge metasomatism. Our work provides insight into the role of high-P phase fractionation on mass redistribution between the surface and deep Earth in subduction zones. Existing limitations relevant to our liquid/mineral speciation/fractionation model will be discussed as well. ReferencesGalvez, M.E., Manning, C.E., Connolly, J.A.D., Rumble, D., 2015. The solubility of rocks in metamorphic fluids: A model for rock-dominated conditions to upper mantle pressure and temperature. Earth Planet. Sci. Lett. 430, 486-498.

Liquid / liquid biphasic electrochemistry in ultra-turrax dispersed acetonitrile / aqueous electrolyte systems

International Nuclear Information System (INIS)

Watkins, John D.; Amemiya, Fumihiro; Atobe, Mahito; Bulman-Page, Philip C.; Marken, Frank

2010-01-01

Unstable acetonitrile | aqueous emulsions generated in situ with ultra-turrax agitation are investigated for applications in dual-phase electrochemistry. Three modes of operation for liquid / liquid aqueous-organic electrochemical processes are demonstrated with no intentionally added electrolyte in the organic phase based on (i) the formation of a water-soluble product in the aqueous phase in the presence of the organic phase, (ii) the formation of a product and ion transfer at the liquid / liquid-electrode triple phase boundary, and (iii) the formation of a water-insoluble product in the aqueous phase which then transfers into the organic phase. A three-electrode electrolysis cell with ultra-turrax agitator is employed and characterised for acetonitrile / aqueous 2 M NaCl two phase electrolyte. Three redox systems are employed in order to quantify the electrolysis cell performance. The one-electron reduction of Ru(NH 3 ) 6 3+ in the aqueous phase is employed to determine the rate of mass transport towards the electrode surface and the effect of the presence of the acetonitrile phase. The one-electron oxidation of n-butylferrocene in acetonitrile is employed to study triple phase boundary processes. Finally, the one-electron reduction of cobalticenium cations in the aqueous phase is employed to demonstrate the product transfer from the electrode surface into the organic phase. Potential applications in biphasic electrosynthesis are discussed.

Equilibrium and non-equilibrium extraction separation of rare earth metals in presence of diethylenetriaminepentaacetic acid in aqueous phase

International Nuclear Information System (INIS)

Azis, Abdul; Teramoto, Masaaki; Matsuyama, Hideto.

1995-01-01

Equilibrium and non-equilibrium extraction separations of rare earth metals were carried out in the presence of chelating agent in the aqueous phase. The separation systems of the rare earth metal mixtures used were Y/Dy, Y/Ho, Y/Er and Y/Tm, and the chelating agent and the extractant were diethylenetriaminepentaacetic acid (DTPA) and bis (2,4,4-trimethylpentyl) phosphinic acid (CYANEXR 272), respectively. For Y/Dy and Y/Ho systems, higher selectivities were obtained in equilibrium separation compared with those in non-equilibrium separation. On the other hand, the selectivities in non-equilibrium separation were higher for Y/Er and Y/Tm systems. In the separation condition suitable to each system, the addition of DTPA to the aqueous phase was found to be very effective for obtaining higher selectivities. The distribution ratios of the rare earth metals and the selectivities in the equilibrium separations obtained experimentally were thoroughly analyzed by considering various equilibria such as the extraction equilibrium and the complex formation equilibrium between rare earth metals and DTPA in the aqueous phase. Moreover, the extraction rates and the selectivities in the non-equilibrium separations were also analyzed by the extraction model considering the dissociation reactions of the rare earth metal-DTPA complexes in the aqueous stagnant layer. Based on these analyses, we presented an index which is useful for selecting the optimum operation mode. Using this index, we can predict that the selectivities under equilibrium conditions are higher than those under non-equilibrium conditions for Y/Dy and Y/Ho systems, while for Y/Er and Y/Tm systems, higher selectivities are obtained under non-equilibrium conditions. The experimental results were in agreement with predictions by this index. Further, the selectivities in various systems including other chelating agents and extractants were discussed based on this index. (J.P.N.)

Triton X-114 based cloud point extraction: a thermoreversible approach for separation/concentration and dispersion of nanomaterials in the aqueous phase.

Science.gov (United States)

Liu, Jing-fu; Liu, Rui; Yin, Yong-guang; Jiang, Gui-bin

2009-03-28

Capable of preserving the sizes and shapes of nanomaterials during the phase transferring, Triton X-114 based cloud point extraction provides a general, simple, and cost-effective route for reversible concentration/separation or dispersion of various nanomaterials in the aqueous phase.

Internalized stigma in adults with early phase versus prolonged psychosis.

Science.gov (United States)

Firmin, Ruth L; Lysaker, Paul H; Luther, Lauren; Yanos, Philip T; Leonhardt, Bethany; Breier, Alan; Vohs, Jenifer L

2018-03-30

Although internalized stigma is associated with negative outcomes among those with prolonged psychosis, surprisingly little work has focused on when in the course of one's illness stigma is internalized and the impact of internalization on symptoms or social functioning over the course of the illness. Therefore, this study investigated whether (1) internalized stigma is greater among those later in the course of psychosis and (2) whether internalized stigma has a stronger negative relationship with social functioning or symptoms among those with prolonged compared to early phase psychosis. Individuals with early phase (n = 40) and prolonged psychosis (n = 71) who were receiving outpatient services at an early-intervention clinic and a VA medical center, respectively, completed self-report measures of internalized stigma and interview-rated measures of symptoms and social functioning. Controlling for education, race and sex differences, internalized stigma was significantly greater among those with prolonged psychosis compared to early phase. Internalized stigma was negatively related to social functioning and positively related to symptoms in both groups. Furthermore, the magnitude of the relationship between cognitive symptoms and internalized stigma was significantly greater among those with early phase. Stereotype endorsement, discrimination experiences and social withdrawal also differentially related to symptoms and social functioning across the 2 samples. Findings suggest that internalized stigma is an important variable to incorporate into models of early psychosis. Furthermore, internalized stigma may be a possible treatment target among those with early phase psychosis. © 2018 John Wiley & Sons Australia, Ltd.

Secondary organic aerosol (trans)formation through aqueous phase guaiacol photonitration: a kinetic study

Science.gov (United States)

Kroflič, Ana; Grgić, Irena

2014-05-01

It is well known that atmospheric aerosols play a crucial role in the Earth's climate and public health (Pöschl 2005). Despite a great effort invested in the studies of secondary organic aerosol (SOA) budget, composition, and its formation mechanisms, there is still a gap between field observations and atmospheric model predictions (Heald et al. 2005, Hallquist et al. 2009, and Lim et al. 2010). The insisting uncertainties surrounding SOA formation and aging thus gained an increasing interest in atmospheric aqueous phase chemistry; they call for more complex and time consuming studies at the environmentally relevant conditions allowing confident extrapolation to desired ambient conditions. In addition to the adverse health effects of atmospheric particulate matter (PM) as such, toxicity is also attributed to nitro-aromatic and other organic compounds which have already been detected in real aerosol samples (Traversi et al. 2009). Moreover, low-volatility aromatic derivatives are believed to form at least partly in the aerosol aqueous phase and not only in the gas phase from where they partition into water droplets (Ervens et al. 2011). Two nitro derivatives of biomass burning tracer guaiacol have recently been found in winter PM10 samples from the city of Ljubljana, Slovenia, and aqueous photonitration reaction was proposed as their possible production pathway (Kitanovski et al. 2012). In this study the kinetics of guaiacol nitration in aqueous solution was investigated in the presence of H2O2 and NO2¯ upon simulated solar irradiation (Xenon lamp, 300 W). During the experiment the DURAN® flask with the reaction mixture was held in the thermostated bath and thoroughly mixed. The reaction was monitored for 44 hours at different temperatures. Guaiacol and its main nitro-products (4-nitroguaiacol, 4-NG; 6-nitroguaiacol, 6-NG; and 4,6-dinitroguaiacol, 4,6-DNG) were quantified in every aliquot, taken from the reaction mixture, by use of high pressure liquid

Carbon-coated ceramic membrane reactor for the production of hydrogen by aqueous-phase reforming of sorbitol.

Science.gov (United States)

Neira D'Angelo, M F; Ordomsky, V; Schouten, J C; van der Schaaf, J; Nijhuis, T A

2014-07-01

Hydrogen was produced by aqueous-phase reforming (APR) of sorbitol in a carbon-on-alumina tubular membrane reactor (4 nm pore size, 7 cm long, 3 mm internal diameter) that allows the hydrogen gas to permeate to the shell side, whereas the liquid remains in the tube side. The hydrophobic nature of the membrane serves to avoid water loss and to minimize the interaction between the ceramic support and water, thus reducing the risks of membrane degradation upon operation. The permeation of hydrogen is dominated by the diffusivity of the hydrogen in water. Thus, higher operation temperatures result in an increase of the flux of hydrogen. The differential pressure has a negative effect on the flux of hydrogen due to the presence of liquid in the larger pores. The membrane was suitable for use in APR, and yielded 2.5 times more hydrogen than a reference reactor (with no membrane). Removal of hydrogen through the membrane assists in the reaction by preventing its consumption in undesired reactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Aqueous-phase mechanism for secondary organic aerosol formation from isoprene: application to the southeast United States and co-benefit of SO2 emission controls

Science.gov (United States)

Isoprene emitted by vegetation is an important precursor of secondary organic aerosol (SOA), but the mechanism and yields are uncertain. Aerosol is prevailingly aqueous under the humid conditions typical of isoprene-emitting regions. Here we develop an aqueous-phase mechanism for...

Design of functional guanidinium ionic liquid aqueous two-phase systems for the efficient purification of protein

Energy Technology Data Exchange (ETDEWEB)

Ding, Xueqin; Wang, Yuzhi, E-mail: wyzss@hnu.edu.cn; Zeng, Qun; Chen, Jing; Huang, Yanhua; Xu, Kaijia

2014-03-01

Graphical abstract: - Highlights: • A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been synthesized. • Functional guanidinium ionic liquid aqueous two-phase systems have been first designed for the purification of protein. • Mechanisms and performances of the process were researched. • Simple, green, safety and presents better purified ability than ordinary process. • A potential efficient platform for protein purification and related studies. - Abstract: A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been devised and synthesized based on 1,1,3,3-tetramethylguanidine. The structures of the ionic liquids (ILs) were confirmed by {sup 1}H nuclear magnetic resonance ({sup 1}H NMR) and 13C nuclear magnetic resonance (13C NMR) and the production yields were all above 90%. Functional guanidinium ionic liquid aqueous two-phase systems (FGIL-ATPSs) have been first designed with these functional guanidinium ILs and phosphate solution for the purification of protein. After phase separation, proteins had transferred into the IL-rich phase and the concentrations of proteins were determined by measuring the absorbance at 278 nm using an ultra violet visible (UV–vis) spectrophotometer. The advantages of FGIL-ATPSs were compared with ordinary ionic liquid aqueous two-phase systems (IL-ATPSs). The proposed FGIL-ATPS has been applied to purify lysozyme, trypsin, ovalbumin and bovine serum albumin. Single factor experiments were used to research the effects of the process, such as the amount of ionic liquid (IL), the concentration of salt solution, temperature and the amount of protein. The purification efficiency reaches to 97.05%. The secondary structure of protein during the experimental process was observed upon investigation using UV–vis spectrophotometer, Fourier-transform infrared

Multiphase flow and transport caused by spontaneous gas phase growth in the presence of dense non-aqueous phase liquid.

Science.gov (United States)

Roy, James W; Smith, James E

2007-01-30

Disconnected bubbles or ganglia of trapped gas may occur below the top of the capillary fringe through a number of mechanisms. In the presence of dense non-aqueous phase liquid (DNAPL), the disconnected gas phase experiences mass transfer of dissolved gases, including volatile components from the DNAPL. The properties of the gas phase interface can also change. This work shows for the first time that when seed gas bubbles exist spontaneous gas phase growth can be expected to occur and can significantly affect water-gas-DNAPL distributions, fluid flow, and mass transfer. Source zone behaviour was observed in three different experiments performed in a 2-dimensional flow cell. In each case, a DNAPL pool was created in a zone of larger glass beads over smaller glass beads, which served as a capillary barrier. In one experiment effluent water samples were analyzed to determine the vertical concentration profile of the plume above the pool. The experiments effectively demonstrated a) a cycle of spontaneous gas phase expansion and vertical advective mobilization of gas bubbles and ganglia above the DNAPL source zone, b) DNAPL redistribution caused by gas phase growth and mobilization, and c) that these processes can significantly affect mass transport from a NAPL source zone.

Liquid-liquid phase separation in internally mixed magnesium sulfate/glutaric acid particles

Science.gov (United States)

Wu, Feng-Min; Wang, Xiao-Wei; Jing, Bo; Zhang, Yun-Hong; Ge, Mao-Fa

2018-04-01

The confocal Raman microscopy is utilized to investigate the liquid-liquid phase separation (LLPS) of mixed magnesium sulfate/glutaric acid (MgSO4/GA) droplets deposited on a hydrophobic polytetrafluoroethylene (PTFE) substrate and a hydrophilic quartz substrate. Raman spectra collected from different regions of the mixed droplets provide detailed information of component distributions for MgSO4 and GA. During the dehydration process, the MgSO4/GA mixed particles show the initial liquid-liquid phase separation between 85% and 80% relative humidity (RH) on both the hydrophobic and hydrophilic substrates. For the droplets deposited on the two substrates, the inner phase of droplets is dominated by aqueous MgSO4, which is surrounded by a rich GA organic layer due to the surface tension effects. In addition, the crystallization of GA could be observed in the organic aqueous phase while it is inhibited in the inner MgSO4 phase due to the effects of gel formation of MgSO4 at low RH. The Raman spectra reveal that with decreasing RH the morphology of the mixed droplet evolves from a uniform droplet to the structure of LLPS with the GA crystallizing in the outer layer and MgSO4 gel formed in the inner phase. These findings contribute to the further understanding of the role of interactions between inorganic salts and organic acids on the morphological evolution and environmental effects of atmospheric aerosols under ambient RH conditions.

Mechanistic insights into aqueous phase propanol dehydration in H-ZSM-5 zeolite

Energy Technology Data Exchange (ETDEWEB)

Mei, Donghai [Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate & Institute for Integrated Catalysis, Richland WA 99352; Lercher, Johannes A. [Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate & Institute for Integrated Catalysis, Richland WA 99352; Dept. of Chemistry and Catalysis Research Institute, TU München, Lichtenbergstrasse 4 Garching 85748 Germany

2016-10-06

Aqueous phase dehydration of 1-propanol over H-ZSM-5 zeolite was investigated using density functional theory (DFT) calculations. The water molecules in the zeolite pores prefer to aggregate via the hydrogen bonding network and be protonated at the Brønsted acidic sites (BAS). Two typical configurations, i.e., dispersed and clustered, of water molecules were identified by ab initio molecular dynamics simulation of the mimicking aqueous phase H-ZSM-5 zeolite unit cell with 20 water molecules per unit cell. DFT calculated Gibbs free energies suggest that the dimeric propanol-propanol, the propanol-water complex, and the trimeric propanol-propanol-water are formed at high propanol concentrations, which provide a kinetically feasible dehydration reaction channel of 1-propanol to propene. However, calculation results also indicate that the propanol dehydration via the unimolecular mechanism becomes kinetically discouraged due to the enhanced stability of the protonated dimeric propanol and the protonated water cluster acting as the BAS site for alcohol dehydration reaction. This work was supported by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). EMSL is a national scientific user facility located at Pacific Northwest National Laboratory (PNNL) and sponsored by DOE’s Office of Biological and Environmental Research.

Aqueous phase oxidation techniques as an alternative to incineration

International Nuclear Information System (INIS)

Gray, L.W.; Adamson, M.G.; Hickman, R.G.; Farmer, J.C.; Chiba, Z.; Gregg, D.W.; Wang, F.T.

1992-03-01

The Lawrence Livermore National Laboratory (LLNL) has three aqueous phase techniques under development for oxidation of high value or high risk waste steams. One is direct electrochemical oxidation and one is mediated electrochemical oxidation utilizing regenerable, strongly oxidizing cations such as Ag(II), Co (III), Ce(IV), etc. These cations can either attack oxidizable materials directly and/or indirectly via first reacting with water to generate OH radicals which then attack the oxidizable materials. The third system utilizes H 2 O 2 and UV light to generate OH radicals directly which in turn attack the oxidizable materials. All systems have the advantage of a chemical off-switch in that when the power is turned off, the reaction quickly subsides. All systems operate with low concentrations (typically <5 wt %) of oxidizable materials, therefore, the stored energy for possible run-away reactions is very low. 15 figures, 22 references

Partition Efficiency of High-Pitch Locular Multilayer Coil for Countercurrent Chromatographic Separation of Proteins Using Small-Scale Cross-Axis Coil Planet Centrifuge and Application to Purification of Various Collagenases with Aqueous-Aqueous Polymer Phase Systems.

Science.gov (United States)

Shinomiya, Kazufusa; Kobayashi, Hiroko; Inokuchi, Norio; Nakagomi, Kazuya; Ito, Yoichiro

2011-01-01

Partition efficiency of the high-pitch locular multilayer coil was evaluated in countercurrent chromatographic (CCC) separation of proteins with an aqueous-aqueous polymer phase system using the small-scale cross-axis coil planet centrifuge (X-axis CPC) fabricated in our laboratory. The separation column was specially made by high-pitch (ca 5 cm) winding of 1.0 mm I.D., 2.0 mm O.D. locular tubing compressed at 2 cm intervals with a total capacity of 29.5 mL. The protein separation was performed using a set of stable proteins including cytochrome C, myoglobin, and lysozyme with the 12.5% (w/w) polyethylene glycol (PEG) 1000 and 12.5% (w/w) dibasic potassium phosphate system (pH 9.2) under 1000 rpm of column revolution. This high-pitch locular tubing yielded substantially increased stationary phase retention than the normal locular tubing for both lower and upper mobile phases. In order to demonstrate the capability of the high-pitch locular tubing, the purification of collagenase from the crude commercial sample was carried out using an aqueous-aqueous polymer phase system. Using the 16.0% (w/w) PEG 1000 - 6.3% (w/w) dibasic potassium phosphate - 6.3% (w/w) monobasic potassium phosphate system (pH 6.6), collagenase I, II, V and X derived from Clostridium hystolyticum were separated from other proteins and colored small molecular weight compounds present in the crude commercial sample, while collagenase N-2 and S-1 from Streptomyces parvulus subsp. citrinus were eluted with impurities at the solvent front with the upper phase. The collagenase from C. hystolyticum retained its enzymatic activity in the purified fractions. The overall results demonstrated that the high-pitch locular multilayer coil is effectively used for the CCC purification of bioactive compounds without loss of their enzymatic activities.

Partition Efficiency of High-Pitch Locular Multilayer Coil for Countercurrent Chromatographic Separation of Proteins Using Small-Scale Cross-Axis Coil Planet Centrifuge and Application to Purification of Various Collagenases with Aqueous-Aqueous Polymer Phase Systems

Science.gov (United States)

Shinomiya, Kazufusa; Kobayashi, Hiroko; Inokuchi, Norio; Nakagomi, Kazuya; Ito, Yoichiro

2010-01-01

Partition efficiency of the high-pitch locular multilayer coil was evaluated in countercurrent chromatographic (CCC) separation of proteins with an aqueous-aqueous polymer phase system using the small-scale cross-axis coil planet centrifuge (X-axis CPC) fabricated in our laboratory. The separation column was specially made by high-pitch (ca 5 cm) winding of 1.0 mm I.D., 2.0 mm O.D. locular tubing compressed at 2 cm intervals with a total capacity of 29.5 mL. The protein separation was performed using a set of stable proteins including cytochrome C, myoglobin, and lysozyme with the 12.5% (w/w) polyethylene glycol (PEG) 1000 and 12.5% (w/w) dibasic potassium phosphate system (pH 9.2) under 1000 rpm of column revolution. This high-pitch locular tubing yielded substantially increased stationary phase retention than the normal locular tubing for both lower and upper mobile phases. In order to demonstrate the capability of the high-pitch locular tubing, the purification of collagenase from the crude commercial sample was carried out using an aqueous-aqueous polymer phase system. Using the 16.0% (w/w) PEG 1000 – 6.3% (w/w) dibasic potassium phosphate – 6.3% (w/w) monobasic potassium phosphate system (pH 6.6), collagenase I, II, V and X derived from Clostridium hystolyticum were separated from other proteins and colored small molecular weight compounds present in the crude commercial sample, while collagenase N-2 and S-1 from Streptomyces parvulus subsp. citrinus were eluted with impurities at the solvent front with the upper phase. The collagenase from C. hystolyticum retained its enzymatic activity in the purified fractions. The overall results demonstrated that the high-pitch locular multilayer coil is effectively used for the CCC purification of bioactive compounds without loss of their enzymatic activities. PMID:21869859

Sol-gel transitions and liquid crystal phase transitions in concentrated aqueous suspensions of colloidal gibbsite platelets

NARCIS (Netherlands)

Mourad, M.C.D.; Byelov, D.V.; Petukhov, A.V.; de Winter, D.A.M.; Verkleij, A.J.; Lekkerkerker, H.N.W.

2009-01-01

In this paper, we present a comprehensive study of the sol-gel transitions and liquid crystal phase transitions in aqueous suspensions of positively charged colloidal gibbsite platelets at pH 4-5 over a wide range of particle concentrations (50-600 g/L) and salt concentrations (10-4-10-1 M NaCl). A

Biosurfactant production by Pseudomonas sp. and its role in aqueous phase partitioning and biodegradation of chlorpyrifos.

Science.gov (United States)

Singh, P B; Sharma, S; Saini, H S; Chadha, B S

2009-09-01

To study the effect of biosurfactant on aqueous phase solubility and biodegradation of chlorpyrifos. A Pseudomonas sp. (ChlD), isolated from agricultural soil by enrichment culture technique in the presence of chlorpyrifos, was capable of producing biosurfactant (rhamnolipids) and degrading chlorpyrifos (0.01 g l(-1)). The partially purified rhamnolipid biosurfactant preparation, having a CMC of 0.2 g l(-1), was evaluated for its ability to enhance aqueous phase partitioning and degradation of chlorpyrifos (0.01 g l(-1)) by ChlD strain. The best degradation efficiency was observed at 0.1 g l(-1) supplement of biosurfactant, as validated by GC and HPLC studies. The addition of biosurfactant at 0.1 g l(-1) resulted in more than 98% degradation of chlorpyrifos when compared to 84% in the absence of biosurfactant after 120-h incubation. This first report, to the best of our knowledge, on enhanced degradation of chlorpyrifos in the presence of biosurfactant(s), would help in developing bioremediation protocols to counter accumulation of organophosphates to toxic/carcinogenic levels in environment.

Fundamental thermochemical properties of amino acids: gas-phase and aqueous acidities and gas-phase heats of formation.

Science.gov (United States)

Stover, Michele L; Jackson, Virgil E; Matus, Myrna H; Adams, Margaret A; Cassady, Carolyn J; Dixon, David A

2012-03-08

The gas-phase acidities of the 20 L-amino acids have been predicted at the composite G3(MP2) level. A broad range of structures of the neutral and anion were studied to determine the lowest energy conformer. Excellent agreement is found with the available experimental gas-phase deprotonation enthalpies, and the calculated values are within experimental error. We predict that tyrosine is deprotonated at the CO(2)H site. Cysteine is predicted to be deprotonated at the SH but the proton on the CO(2)H is shared with the S(-) site. Self-consistent reaction field (SCRF) calculations with the COSMO parametrization were used to predict the pK(a)'s of the non-zwitterion form in aqueous solution. The differences in the non-zwitterion pK(a) values were used to estimate the free energy difference between the zwitterion and nonzwitterion forms in solution. The heats of formation of the neutral compounds were calculated from atomization energies and isodesmic reactions to provide the first reliable set of these values in the gas phase. Further calculations were performed on five rare amino acids to predict their heats of formation, acidities, and pK(a) values.

Enhancement in extraction rates by addition of organic acids to aqueous phase in solvent extraction of rare earth metals in presence of diethylenetriaminepentaacetic acid

International Nuclear Information System (INIS)

Matsuyama, Hideto; Azis, A.; Fujita, Mamoru; Teramoto, Masaaki.

1996-01-01

It is well known that the selectivity of rare earth metals by solvent extraction is increased by the addition of a chelating agent such as diethylenetriaminepentaacetic acid (DTPA) in the aqueous phase. One of the disadvantages of this method is the decrease in extraction rates due to complexation in the aqueous phase. In this paper, further addition of organic acids to the aqueous phase was examined for the purpose of enhancing the extraction rates in solvent extraction with DTPA. The addition of several kind of organic acids such as formic acid, acetic acid, malonic acid, lactic acid and citric acid was investigated for a Er/Y separation system. A remarkable enhancement in extraction rates was observed with a slight decrease in the selectivity by the addition of citric acid or lactic acid. Extraction rates in the presence of both DTPA and citric acid increased with the increase in citric acid concentration and with the increase in proton concentration. A 150 times enhancement in extraction rates was found in the low proton concentration condition. In order to analyze the extraction rates and selectivities obtained, mass transfer equations were presented by considering both the dissociation reaction of rare earth metal-DTPA complexes and the complex formation between rare earth metal and organic acid in the aqueous phase. The experimental data were analyzed by these equations. (author)

The salting-out effect and phase separation in aqueous solutions of tri-sodium citrate and 1-butyl-3-methylimidazolium bromide

Energy Technology Data Exchange (ETDEWEB)

Sadeghi, Rahmat, E-mail: rsadeghi@uok.ac.i [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Golabiazar, Roonak [Department of Chemistry, University of Kurdistan, Sanandaj (Iran, Islamic Republic of); Shekaari, Hemayat [Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

2010-04-15

The aim of this work is to obtain further evidence about the salting-out effect produced by the addition of tri-sodium citrate to aqueous solutions of water miscible ionic liquid 1-butyl-3-methylimidazolium bromide ([C{sub 4}mim][Br]) by evaluating the effect of tri-sodium citrate on the thermodynamic properties of aqueous solutions of this ionic liquid. Experimental measurements of density and sound velocity at different temperatures ranging from (288.15 to 308.15) K, the refractive index at 308.15 K and the liquid-liquid phase diagram at different temperatures ranging from (288.15 to 338.15) K for aqueous solutions containing 1-butyl-3-methylimidazolium bromide ([C{sub 4}mim][Br]) and tri-sodium citrate (Na{sub 3}Cit) are taken. The apparent molar volume of transfer of [C{sub 4}mim][Br] from water to aqueous solutions of Na{sub 3}Cit have positive values and it increases by increasing salt molality. Although at high IL molality, the apparent molar isentropic compressibility shows similar behaviour with that of the apparent molar volume. However at low concentrations of IL, the apparent molar isentropic compressibility of transfer of [C{sub 4}mim][Br] from water to aqueous solutions of Na{sub 3}Cit have negative values. The effects of temperature and the addition of Na{sub 3}Cit and [C{sub 4}mim][Br] on the liquid-liquid phase diagram of the investigated system have been studied. It was found that an increase in temperature caused the expansion of the one-phase region. The presence of Na{sub 3}Cit triggers a salting-out effect, leading to significant upward shifts of the liquid-liquid de-mixing temperatures of the system. The effect of temperature on the phase-forming ability in the system investigated has been studied based on a salting-out coefficient obtained from fitting the binodal values to a Setschenow-type equation for each temperature. Based on cloud point values, the energetics of the clouding process have been estimated and it was found that both of

Headspace liquid-phase microextraction of methamphetamine and amphetamine in urine by an aqueous drop

International Nuclear Information System (INIS)

He Yi; Vargas, Angelica; Kang, Youn-Jung

2007-01-01

This study developed a headspace liquid-phase microextraction (LPME) method by using a single aqueous drop in combination with high performance liquid chromatography (HPLC)-UV detection for the determination of methamphetamine (MAP) and amphetamine (AP) in urine samples. The analytes, volatile and basic, were released from sample matrix into the headspace first, and then protonated and dissolved in an aqueous H 3 PO 4 drop hanging in the headspace by a HPLC syringe. After extraction, this drop was directly injected into HPLC. Parameters affecting extraction efficiency were investigated and optimized. This method showed good linearity in the investigated concentration range of 1.0-1500 μg L -1 , repeatability of the extraction (R.S.D. -1 for both analytes). Enrichment factors of about 400-fold and 220-fold were achieved for MAP and AP, respectively, at optimum conditions. The feasibility of the method was demonstrated by analyzing human urine samples

Fabrication of platinum nanoparticles in aqueous solution and solid phase using amphiphilic PB-b-PEO copolymer nanoreactors

International Nuclear Information System (INIS)

Hoda, Numan; Budama, Leyla; Çakır, Burçin Acar; Topel, Önder; Ozisik, Rahmi

2013-01-01

Graphical abstract: TEM image of Pt nanoparticles produced by reducing by NaBH 4 within PB-b-PEO micelles in aqueous media (scale bar 1 nm). - Highlights: • Pt nanoparticles were synthesized within amphiphilic diblock copolymer micelles. • The effects of reducing agents and precursor dose on Pt np size were investigated. • The effect on fabrication of Pt np by reducing in aqueous and solid phases was compared. • The size of nanoparticles was about 1.4 nm for all doses and reducing agents types. - Abstract: Fabrication of Pt nanoparticles using an amphiphilic copolymer template in aqueous solution was achieved via polybutadiene-block-polyethyleneoxide copolymer micelles, which acted as nanoreactors. In addition, Pt nanoparticles were synthesized using hydrogen gas as the reducing agent in solid state for the first time to compare against solution synthesis. The influences of loaded precursor salt amount to micelles and the type of reducing agent on the size of nanoparticles were investigated through transmission electron microscopy. It was found that increasing the ratio of precursor salt to copolymer and using different type of reducing agent, even in solid phase reduction, did not affect the nanoparticle size. The average size of Pt nanoparticles was estimated to be 1.4 ± 0.1 nm. The reason for getting same sized nanoparticles was discussed in the light of nucleation, growth process, stabilization and diffusion of nanoparticles within micelles

A green deep eutectic solvent-based aqueous two-phase system for protein extracting

International Nuclear Information System (INIS)

Xu, Kaijia; Wang, Yuzhi; Huang, Yanhua; Li, Na; Wen, Qian

2015-01-01

Highlights: • A strategy for the protein purification with a deep eutectic solvent(DES)-based aqueous two-phase system. • Choline chloride-glycerin DES was selected as the extraction solvent. • Bovine serum albumin and trypsin were used as the analytes. • Aggregation phenomenon was detected in the mechanism research. - Abstract: As a new type of green solvent, deep eutectic solvent (DES) has been applied for the extraction of proteins with an aqueous two-phase system (ATPS) in this work. Four kinds of choline chloride (ChCl)-based DESs were synthesized to extract bovine serum albumin (BSA), and ChCl-glycerol was selected as the suitable extraction solvent. Single factor experiments have been done to investigate the effects of the extraction process, including the amount of DES, the concentration of salt, the mass of protein, the shaking time, the temperature and PH value. Experimental results show 98.16% of the BSA could be extracted into the DES-rich phase in a single-step extraction under the optimized conditions. A high extraction efficiency of 94.36% was achieved, while the conditions were applied to the extraction of trypsin (Try). Precision, repeatability and stability experiments were studied and the relative standard deviations (RSD) of the extraction efficiency were 0.4246% (n = 3), 1.6057% (n = 3) and 1.6132% (n = 3), respectively. Conformation of BSA was not changed during the extraction process according to the investigation of UV–vis spectra, FT-IR spectra and CD spectra of BSA. The conductivity, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to explore the mechanism of the extraction. It turned out that the formation of DES–protein aggregates play a significant role in the separation process. All the results suggest that ChCl-based DES-ATPS are supposed to have the potential to provide new possibilities in the separation of proteins

Aqueous nitrite ion determination by selective reduction and gas phase nitric oxide chemiluminescence

Science.gov (United States)

Dunham, A. J.; Barkley, R. M.; Sievers, R. E.; Clarkson, T. W. (Principal Investigator)

1995-01-01

An improved method of flow injection analysis for aqueous nitrite ion exploits the sensitivity and selectivity of the nitric oxide (NO) chemilluminescence detector. Trace analysis of nitrite ion in a small sample (5-160 microL) is accomplished by conversion of nitrite ion to NO by aqueous iodide in acid. The resulting NO is transported to the gas phase through a semipermeable membrane and subsequently detected by monitoring the photoemission of the reaction between NO and ozone (O3). Chemiluminescence detection is selective for measurement of NO, and, since the detection occurs in the gas-phase, neither sample coloration nor turbidity interfere. The detection limit for a 100-microL sample is 0.04 ppb of nitrite ion. The precision at the 10 ppb level is 2% relative standard deviation, and 60-180 samples can be analyzed per hour. Samples of human saliva and food extracts were analyzed; the results from a standard colorimetric measurement are compared with those from the new chemiluminescence method in order to further validate the latter method. A high degree of selectivity is obtained due to the three discriminating steps in the process: (1) the nitrite ion to NO conversion conditions are virtually specific for nitrite ion, (2) only volatile products of the conversion will be swept to the gas phase (avoiding turbidity or color in spectrophotometric methods), and (3) the NO chemiluminescence detector selectively detects the emission from the NO + O3 reaction. The method is free of interferences, offers detection limits of low parts per billion of nitrite ion, and allows the analysis of up to 180 microL-sized samples per hour, with little sample preparation and no chromatographic separation. Much smaller samples can be analyzed by this method than in previously reported batch analysis methods, which typically require 5 mL or more of sample and often need chromatographic separations as well.

Spontaneous vesicle phase formation by pseudogemini surfactants in aqueous solutions.

Science.gov (United States)

Sun, Nan; Shi, Lijuan; Lu, Fei; Xie, Shuting; Zheng, Liqiang

2014-08-14

The phase behavior of a kind of pseudogemini surfactant in aqueous solutions, formed by the mixture of sodium dodecyl benzene sulfonate (SDBS) and butane-1,4-bis (methylimidazolium bromide) ([mim-C4-mim]Br2) or butane-1,4-bis(methylpyrrolidinium bromide) ([mpy-C4-mpy]Br2) in a molar ratio of 2 : 1, is reported in the present work. When [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 is mixed with SDBS in aqueous solutions, one cationic [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 molecule "bridges" two SDBS molecules by noncovalent interactions (e.g. electrostatic, π-π stacking, and σ-π interactions), behaving like a pseudogemini surfactant. Vesicles can be formed by this kind of pseudogemini surfactant, determined by freeze-fracture transmission electron microscopy (FF-TEM) or cryogenic-transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS). The mixed system of sodium dodecyl sulfate (SDS) with [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 was also constructed, and only micelles were observed. We infer that a pseudogemini surfactant is formed under the synergic effect of electrostatic, π-π stacking, and σ-π interactions in the SDBS/[mim-C4-mim]Br2/H2O system, while electrostatic attraction and hydrophobic interactions may provide the directional force for vesicle formation in the SDBS/[mpy-C4-mpy]Br2/H2O system.

Hydrogen production by aqueous phase catalytic reforming of glycerine

International Nuclear Information System (INIS)

Ozguer, Derya Oncel; Uysal, Bekir Zuehtue

2011-01-01

Hydrogen is believed to be the one of the main energy carriers in the near future. In this research glycerine, which is produced in large quantities as a by-product of biodiesel process, was converted to hydrogen aiming to contribute to clean energy initiative. Conversion of glycerol to hydrogen was achieved via aqueous-phase reforming (APR) with Pt/Al 2 O 3 catalyst. The experiments were carried out in an autoclave reactor and a continuous fixed-bed reactor. The effects of reaction temperature (160-280 o C), feed flow rate (0.05-0.5 mL/dak) and feed concentration (5-85 wt-% glycerine) on product distribution were investigated. Optimum temperature for hydrogen production with APR was determined as 230 o C. Maximum gas production rate was found at the feed flow rates around 0.1 mL/min. It was also found that hydrogen concentration in the gas product increased with decreasing glycerol concentration in the feed.

Novel Displacement Agents for Aqueous 2-Phase Extraction Can Be Estimated Based on Hybrid Shortcut Calculations.

Science.gov (United States)

Kress, Christian; Sadowski, Gabriele; Brandenbusch, Christoph

2016-10-01

The purification of therapeutic proteins is a challenging task with immediate need for optimization. Besides other techniques, aqueous 2-phase extraction (ATPE) of proteins has been shown to be a promising alternative to cost-intensive state-of-the-art chromatographic protein purification. Most likely, to enable a selective extraction, protein partitioning has to be influenced using a displacement agent to isolate the target protein from the impurities. In this work, a new displacement agent (lithium bromide [LiBr]) allowing for the selective separation of the target protein IgG from human serum albumin (represents the impurity) within a citrate-polyethylene glycol (PEG) ATPS is presented. In order to characterize the displacement suitability of LiBr on IgG, the mutual influence of LiBr and the phase formers on the aqueous 2-phase system (ATPS) and partitioning is investigated. Using osmotic virial coefficients (B22 and B23) accessible by composition gradient multiangle light-scattering measurements, the precipitating effect of LiBr on both proteins and an estimation of both protein partition coefficients is estimated. The stabilizing effect of LiBr on both proteins was estimated based on B22 and experimentally validated within the citrate-PEG ATPS. Our approach contributes to an efficient implementation of ATPE within the downstream processing development of therapeutic proteins. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Headspace liquid-phase microextraction of methamphetamine and amphetamine in urine by an aqueous drop

Energy Technology Data Exchange (ETDEWEB)

He Yi [Department of Sciences, John Jay College of Criminal Justice, City University of New York, 445 W 59th Street, New York, NY 10019 (United States)]. E-mail: yhe@jjay.cuny.edu; Vargas, Angelica [Department of Sciences, John Jay College of Criminal Justice, City University of New York, 445 W 59th Street, New York, NY 10019 (United States); Kang, Youn-Jung [Department of Sciences, John Jay College of Criminal Justice, City University of New York, 445 W 59th Street, New York, NY 10019 (United States)

2007-04-25

This study developed a headspace liquid-phase microextraction (LPME) method by using a single aqueous drop in combination with high performance liquid chromatography (HPLC)-UV detection for the determination of methamphetamine (MAP) and amphetamine (AP) in urine samples. The analytes, volatile and basic, were released from sample matrix into the headspace first, and then protonated and dissolved in an aqueous H{sub 3}PO{sub 4} drop hanging in the headspace by a HPLC syringe. After extraction, this drop was directly injected into HPLC. Parameters affecting extraction efficiency were investigated and optimized. This method showed good linearity in the investigated concentration range of 1.0-1500 {mu}g L{sup -1}, repeatability of the extraction (R.S.D. < 5%, n = 6), and low detection limits (0.3 {mu}g L{sup -1} for both analytes). Enrichment factors of about 400-fold and 220-fold were achieved for MAP and AP, respectively, at optimum conditions. The feasibility of the method was demonstrated by analyzing human urine samples.

Liquid-liquid equilibrium of water + PEG 8000 + magnesium sulfate or sodium sulfate aqueous two-phase systems at 35°C: experimental determination and thermodynamic modeling

Directory of Open Access Journals (Sweden)

B. D. Castro

2005-09-01

Full Text Available Liquid-liquid extraction using aqueous two-phase systems is a highly efficient technique for separation and purification of biomolecules due to the mild properties of both liquid phases. Reliable data on the phase behavior of these systems are essential for the design and operation of new separation processes; several authors reported phase diagrams for polymer-polymer systems, but data on polymer-salt systems are still relatively scarce. In this work, experimental liquid-liquid equilibrium data on water + polyethylene glycol 8000 + magnesium sulfate and water + polyethylene glycol 8000 + sodium sulfate aqueous two-phase systems were obtained at 35°C. Both equilibrium phases were analyzed by lyophilization and ashing. Experimental results were correlated with a mass-fraction-based NRTL activity coefficient model. New interaction parameters were estimated with the Simplex method. The mean deviations between the experimental and calculated compositions in both equilibrium phases is about 2%.

Retention of ionisable compounds on high-performance liquid chromatography. XV. Estimation of the pH variation of aqueous buffers with the change of the acetonitrile fraction of the mobile phase.

Science.gov (United States)

Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

2004-12-03

The most commonly used mobile phases in reversed-phase high-performance liquid chromatography (RP-HPLC) are hydro-organic mixtures of an aqueous buffer and an organic modifier. The addition of this organic solvent to buffered aqueous solutions involves a variation of the buffer properties (pH and buffer capacity). In this paper, the pH variation is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-citrate, and ammonium-ammonia buffers. The proposed equations allow pH estimation of acetonitrile-water buffered mobile phases up to 60% (v/v) of organic modifier and initial aqueous buffer concentrations between 0.001 and 0.1 mol L(-1), from the initial aqueous pH. The estimated pH variation of the mobile phase and the pKa variation of the analytes allow us to predict the degree of ionisation of the analytes and from this and analyte hydrophobicities, to interpret the relative retention and separation of analyte mixtures.

New lipid family that forms inverted cubic phases in equilibrium with excess water: molecular structure-aqueous phase structure relationship for lipids with 5,9,13,17-tetramethyloctadecyl and 5,9,13,17-tetramethyloctadecanoyl chains.

Science.gov (United States)

Yamashita, Jun; Shiono, Manzo; Hato, Masakatsu

2008-10-02

With a view to discovering a new family of lipids that form inverted cubic phases, the aqueous phase behavior of a series of lipids with isoprenoid-type hydrophobic chains has been examined over a temperature range from -40 to 65 degrees C by using optical microscopy, DSC (differential scanning calorimetry), and SAXS (small-angle X-ray scattering) techniques. The lipids examined are those with 5,9,13,17-tetramethyloctadecyl and 5,9,13,17-tetramethyloctadecanoyl chains linked to a series of headgroups, that is, erythritol, pentaerythritol, xylose, and glucose. All of the lipid/water systems displayed a "water + liquid crystalline phase" two-phase coexistence state when sufficiently diluted. The aqueous phase structures of the most diluted liquid crystalline phases in equilibrium with excess water depend both on the lipid molecular structure and on the temperature. Given an isoprenoid chain, the preferred phase consistently follows a phase sequence of an H II (an inverted hexagonal phase) to a Q II (an inverted bicontinuous cubic phase) to an L alpha (a lamellar phase) as A* (cross-section area of the headgroup) increases. For a given lipid/water system, the phase sequence observed as the temperature increases is L alpha to Q II to H II. The present study allowed us to find four cubic phase-forming lipid species, PEOC 18+4 [mono- O-(5,9,13,17-tetramethyloctadecyl)pentaerythritol], beta-XylOC 18+4 [1- O-(5,9,13,17-tetramethyloctadecyl)-beta- d-xylopyranoside], EROCOC 17+4 [1- O-(5,9,13,17-tetramethyloctadecanoyl)erythritol], and PEOCOC 17+4 [mono- O-(5,9,13,17-tetramethyloctadecanoyl)pentaerythritol]. The values of T K (hydrated solid-liquid crystalline phase transition temperature) of the cubic phase-forming lipids are all below 0 degrees C. Quantitative analyses of the lipid molecular structure-aqueous phase structure relationship in terms of the experimentally evaluated "surfactant parameter" allow us to rationally select an optimum combination of hydrophilic

A propofol microemulsion with low free propofol in the aqueous phase: formulation, physicochemical characterization, stability and pharmacokinetics.

Science.gov (United States)

Cai, WeiHui; Deng, WanDing; Yang, HuiHui; Chen, XiaoPing; Jin, Fang

2012-10-15

The purpose of this study was to develop a propofol microemulsion with a low concentration of free propofol in the aqueous phase. Propofol microemulsions were prepared based on single-factor experiments and orthogonal design. The optimal microemulsion was evaluated for pH, osmolarity, particle size, zeta potential, morphology, free propofol in the aqueous phase, stability, and pharmacokinetics in beagle dogs, and comparisons made with the commercial emulsion, Diprivan(®). The pH and osmolarity of the microemulsion were similar to those of Diprivan(®). The average particle size was 22.6±0.2 nm, and TEM imaging indicated that the microemulsion particles were spherical in appearance. The concentration of free propofol in the microemulsion was 21.3% lower than that of Diprivan(®). Storage stability tests suggested that the microemulsion was stable long-term under room temperature conditions. The pharmacokinetic profile for the microemulsion showed rapid distribution and elimination compared to Diprivan(®). We conclude that the prepared microemulsion may be clinically useful as a potential carrier for propofol delivery. Copyright © 2012 Elsevier B.V. All rights reserved.

A plant wide aqueous phase chemistry model describing pH variations and ion speciation/pairing in wastewater treatment process models

DEFF Research Database (Denmark)

Flores-Alsina, X.; Mbamba, C. Kazadi; Solon, K.

cationic/anionic loads. In this way, the general applicability/flexibility of the proposed approach is demonstrated by implementing the aqueous phase chemistry module in some of the most frequently used WWTP process simulation models. Finally, it is shown how traditional wastewater modelling studies can......, require a major, but unavoidable, additional degree of complexity when representing cationic/anionic behaviour in Activated Sludge (AS)/Anaerobic Digestion (AD) systems (Ikumi et al., 2014). In this paper, a plant-wide aqueous phase chemistry module describing pH variations plus ion speciation...... of Ordinary Differential Equations (ODEs) in order to reduce the overall stiffness of the system, thereby enhancing simulation speed. Additionally, a multi-dimensional version of the Newton-Raphson algorithm is applied to handle the existing multiple algebraic inter-dependencies (Solon et al., 2015...

A plant-wide aqueous phase chemistry module describing pH variations and ion speciation/pairing in wastewater treatment process models

DEFF Research Database (Denmark)

Flores Alsina, Xavier; Kazadi Mbamba, Christian; Solon, Kimberly

2015-01-01

at different cationic/anionic loads. In this way, the general applicability/flexibility of the proposed approach is demonstrated, by implementing the aqueous phase chemistry module in some of the most frequently used WWTP process simulation models. Finally, it is shown how traditional wastewater modelling......, but unavoidable, additional degree of complexity when representing cationic/anionic behaviour in Activated Sludge (AS)/Anaerobic Digestion (AD) systems. In this paper, a plant-wide aqueous phase chemistry module describing pH variations plus ion speciation/pairing is presented and interfaced with industry......) in order to reduce the overall stiffness of the system, thereby enhancing simulation speed. Additionally, a multi-dimensional version of the Newton-Raphson algorithm is applied to handle the existing multiple algebraic inter-dependencies. The latter is reinforced with the Simulated Annealing method...

Aqueous-phase oxidation of green leaf volatiles by hydroxyl radical as a source of SOA: Product identification from methyl jasmonate and methyl salicylate oxidation

Science.gov (United States)

Hansel, Amie K.; Ehrenhauser, Franz S.; Richards-Henderson, Nicole K.; Anastasio, Cort; Valsaraj, Kalliat T.

2015-02-01

Green leaf volatiles (GLVs) are a group of biogenic volatile organic compounds (BVOCs) released into the atmosphere by vegetation. BVOCs produce secondary organic aerosol (SOA) via gas-phase reactions, but little is known of their aqueous-phase oxidation as a source of SOA. GLVs can partition into atmospheric water phases, e.g., fog, mist, dew or rain, and be oxidized by hydroxyl radicals (˙OH). These reactions in the liquid phase also lead to products that have higher molecular weights, increased polarity, and lower vapor pressures, ultimately forming SOA after evaporation of the droplet. To examine this process, we investigated the aqueous, ˙OH-mediated oxidation of methyl jasmonate (MeJa) and methyl salicylate (MeSa), two GLVs that produce aqueous-phase SOA. High performance liquid chromatography/electrospray ionization mass spectrometry (HPLC-ESI-MS) was used to monitor product formation. The oxidation products identified exhibit higher molecular mass than their parent GLV due to either dimerization or the addition of oxygen and hydroxyl functional groups. The proposed structures of potential products are based on mechanistic considerations combined with the HPLC/ESI-MS data. Based on the structures, the vapor pressure and the Henry's law constant were estimated with multiple methods (SPARC, SIMPOL, MPBPVP, Bond and Group Estimations). The estimated vapor pressures of the products identified are significantly (up to 7 orders of magnitude) lower than those of the associated parent compounds, and therefore, the GLV oxidation products may remain as SOA after evaporation of the water droplet. The contribution of the identified oxidation products to SOA formation is estimated based on measured HPLC-ESI/MS responses relative to previous aqueous SOA mass yield measurements.

Correlation and Prediction of Thermal Properties and Phase Behaviour for a Class of Aqueous Electrolyte Systems

DEFF Research Database (Denmark)

Thomsen, Kaj; Rasmussen, Peter; Gani, Rafiqul

1996-01-01

An extended UNIQUAC model is used to describe phase behaviour (VLE, SLE) and thermal properties (heat of mixing, heat capacity) for aqueous solutions containing ions like (Na+, K+, H+) (Cl-, NO3-, SO42-, OH-, CO3-). A linear temperature dependence of the binary interaction parameters allows good...... agreement with experimental data in the temperature range 0-110 degrees C. Copyright (C) 1996 Elsevier Science Ltd...

Programme of research into the management and storage of radioactive waste. Aqueous phase transport through granitic rocks

International Nuclear Information System (INIS)

Bradbury, M.H.; Green, A.

1984-01-01

Three aspects of work on aqueous phase transport by diffusion through porous granites are considered (1) The formation factor and long range connectivity of pore structure. (2) The effect of degraded fissure surfaces on diffusion into the main pore structure. (3) Effect of overburden pressures at depth on diffusion rates. Experiments were conducted on Cornish carnmenellis granite. (U.K.)

Combination of size selective binding ability of 18-crown-6 dissolved in aqueous phase and extractive properties of an amic acid; toward enhancement of rare earths separation

Energy Technology Data Exchange (ETDEWEB)

Safarbali, Reyhaneh; Yaftian, Mohammad Reza; Ghorbanloo, Massomeh [Zanjan Univ. (Iran, Islamic Republic of). PhaseEquilibria Research Lab.; Zamani, Abbasali [Zanjan Univ. (Iran, Islamic Republic of). Environmental Science Research Lab.

2016-11-15

The separation of La(III), Eu(III) and Er(III) ions by an amic acid, N,N-dioctyldiglycolamic acid (HL), dissolved in carbon tetrachloride has been improved in the presence of 18-crown-6 (18C6) in aqueous phase as a selective masking agent. The interaction between the studied metal ions and 18C6 resulted a shift in the extraction curve of the studied metal ions versus pH toward higher pH region. The displacement of the extraction curves was more pronounced for lanthanum ions and was varied as La(III) > Eu(III) > Er(III). This order of complexing ability of 18C6 toward the studied ions was attributed to the size adaptation of the ions and that of the crown ether cavity. The stability constants of the lanthanide-crown ether complexes in aqueous phase were evaluated. The influence of temperature on the extraction of studied metal ions from aqueous phase in the absence and the presence of 18C6 was tested in the range 298-308 K. This investigation allowed evaluating the thermodynamic parameters associated with the extraction process and those of the complexation of cations by 18C6 in the aqueous phase.

An example of transition from a corrosion process in gaseous phase to corrosion in aqueous environment: the case of Z2CN18-10 stainless steel by iodine and water in vapour phase

International Nuclear Information System (INIS)

Mathieu, Bruno

1990-01-01

This research thesis addresses an example of transition of a corrosion process in gaseous phase towards corrosion in aqueous environment, specifically in the case of the corrosion of the Z2CN18-10 stainless steel by gaseous iodine in presence of water vapour (and possibly nitrogen dioxide). This transition occurs in two steps: initiation in gaseous phase and growth in aqueous environment. This transition is due to hygroscopic properties of mostly chromium iodides and, to a lesser extent, iron iodides. Morphological, electrochemical and thermogravimetry studies have been performed by varying different parameters governing corrosion processes: corrosion temperature, iodine concentration, relative humidity, and reaction time [fr

Linear free energy relationships between aqueous phase hydroxyl radical reaction rate constants and free energy of activation.

Science.gov (United States)

Minakata, Daisuke; Crittenden, John

2011-04-15

The hydroxyl radical (HO(•)) is a strong oxidant that reacts with electron-rich sites on organic compounds and initiates complex radical chain reactions in aqueous phase advanced oxidation processes (AOPs). Computer based kinetic modeling requires a reaction pathway generator and predictions of associated reaction rate constants. Previously, we reported a reaction pathway generator that can enumerate the most important elementary reactions for aliphatic compounds. For the reaction rate constant predictor, we develop linear free energy relationships (LFERs) between aqueous phase literature-reported HO(•) reaction rate constants and theoretically calculated free energies of activation for H-atom abstraction from a C-H bond and HO(•) addition to alkenes. The theoretical method uses ab initio quantum mechanical calculations, Gaussian 1-3, for gas phase reactions and a solvation method, COSMO-RS theory, to estimate the impact of water. Theoretically calculated free energies of activation are found to be within approximately ±3 kcal/mol of experimental values. Considering errors that arise from quantum mechanical calculations and experiments, this should be within the acceptable errors. The established LFERs are used to predict the HO(•) reaction rate constants within a factor of 5 from the experimental values. This approach may be applied to other reaction mechanisms to establish a library of rate constant predictions for kinetic modeling of AOPs.

Theoretical study of phase behaviour of DLVO model for lysozyme and γ-crystalline aqueous electrolyte solutions

Directory of Open Access Journals (Sweden)

R. Melnyk

2015-03-01

Full Text Available Mean spherical approximation (MSA, second-order Barker-Henderson (BH perturbation theory and thermodynamic perturbation theory (TPT for associating fluids in combination with BH perturbation theory are applied to the study of the structural properties and phase behaviour of the Derjaguin-Landau-Verwey-Overbeek (DLVO model of lysozyme and γ-cristalline aqueous electrolyte solutions. Predictions of the MSA for the structure factors are in good agreement with the corresponding computer simulation predictions. The agreement between theoretical results for the liquid-gas phase diagram and the corresponding results of the experiment and computer simulation is less satisfactory, with predictions of the combined BH-TPT approach being the most accurate.

Characterisation of UV-cured acrylate networks by means of hydrolysis followed by aqueous size-exclusion combined with reversed-phase chromatography

NARCIS (Netherlands)

Peters, R.; Litvinov, V. M.; Steeman, P.; Dias, A. A.; Mengerink, Y.; van Benthem, R.; de Koster, C. G.; van der Wal, S. J.; Schoenmakers, P.

2007-01-01

UV-cured networks prepared from mixtures of di-functional (polyethylene-glycol di-acrylate) and mono-functional (2-ethylhexyl acrylate) acrylates were analysed after hydrolysis, by aqueous size-exclusion chromatography coupled to on-line reversed-phase liquid-chromatography. The mean network density

Unique aqueous Li-ion/sulfur chemistry with high energy density and reversibility.

Science.gov (United States)

Yang, Chongyin; Suo, Liumin; Borodin, Oleg; Wang, Fei; Sun, Wei; Gao, Tao; Fan, Xiulin; Hou, Singyuk; Ma, Zhaohui; Amine, Khalil; Xu, Kang; Wang, Chunsheng

2017-06-13

Leveraging the most recent success in expanding the electrochemical stability window of aqueous electrolytes, in this work we create a unique Li-ion/sulfur chemistry of both high energy density and safety. We show that in the superconcentrated aqueous electrolyte, lithiation of sulfur experiences phase change from a high-order polysulfide to low-order polysulfides through solid-liquid two-phase reaction pathway, where the liquid polysulfide phase in the sulfide electrode is thermodynamically phase-separated from the superconcentrated aqueous electrolyte. The sulfur with solid-liquid two-phase exhibits a reversible capacity of 1,327 mAh/(g of S), along with fast reaction kinetics and negligible polysulfide dissolution. By coupling a sulfur anode with different Li-ion cathode materials, the aqueous Li-ion/sulfur full cell delivers record-high energy densities up to 200 Wh/(kg of total electrode mass) for >1,000 cycles at ∼100% coulombic efficiency. These performances already approach that of commercial lithium-ion batteries (LIBs) using a nonaqueous electrolyte, along with intrinsic safety not possessed by the latter. The excellent performance of this aqueous battery chemistry significantly promotes the practical possibility of aqueous LIBs in large-format applications.

Aqueous phase complexation of Cm(III) and Cf(III) with ionizable macrocyclic ligands

International Nuclear Information System (INIS)

Manchanda, V.K.; Mohapatra, P.K.

1995-01-01

Complexation behaviour of Cm(III) and Cf(III) with 1,7-diaza-4,10,13-trioxacyclopentadecane-N,N'-diacetic acid (K21DA), 1,10-diaza-4,7,13,16-tetraoxacyclooctadecane-N,N'-diacetic acid (K22DA) and ethylene diamine N,N'- diacetic acid (EDDA) has been investigated using dinonyl naphthalene sulphonic acid (DNNS), in tetramethyl ammonium form as liquid cation exchanger. The aqueous phase complex formation constants are computed from the distribution data. Though larger complex formation constants are observed with K21DA as well as K22DA compared to those with the acyclic analog EDDA, no size correlation is observed. (author). 5 refs., 1 tab

Design of functional guanidinium ionic liquid aqueous two-phase systems for the efficient purification of protein.

Science.gov (United States)

Ding, Xueqin; Wang, Yuzhi; Zeng, Qun; Chen, Jing; Huang, Yanhua; Xu, Kaijia

2014-03-07

A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been devised and synthesized based on 1,1,3,3-tetramethylguanidine. The structures of the ionic liquids (ILs) were confirmed by (1)H nuclear magnetic resonance ((1)H NMR) and 13C nuclear magnetic resonance (13C NMR) and the production yields were all above 90%. Functional guanidinium ionic liquid aqueous two-phase systems (FGIL-ATPSs) have been first designed with these functional guanidinium ILs and phosphate solution for the purification of protein. After phase separation, proteins had transferred into the IL-rich phase and the concentrations of proteins were determined by measuring the absorbance at 278 nm using an ultra violet visible (UV-vis) spectrophotometer. The advantages of FGIL-ATPSs were compared with ordinary ionic liquid aqueous two-phase systems (IL-ATPSs). The proposed FGIL-ATPS has been applied to purify lysozyme, trypsin, ovalbumin and bovine serum albumin. Single factor experiments were used to research the effects of the process, such as the amount of ionic liquid (IL), the concentration of salt solution, temperature and the amount of protein. The purification efficiency reaches to 97.05%. The secondary structure of protein during the experimental process was observed upon investigation using UV-vis spectrophotometer, Fourier-transform infrared spectroscopy (FT-IR) and circular dichroism spectrum (CD spectrum). The precision, stability and repeatability of the process were investigated. The mechanisms of purification were researched by dynamic light scattering (DLS), determination of the conductivity and transmission electron microscopy (TEM). It was suggested that aggregation and embrace phenomenon play a significant role in the purification of proteins. All the results show that FGIL-ATPSs have huge potential to offer new possibility in the purification of proteins. Copyright © 2014 Elsevier B.V. All rights

Retention of ionisable compounds on high-performance liquid chromatography XVII. Estimation of the pH variation of aqueous buffers with the change of the methanol fraction of the mobile phase.

Science.gov (United States)

Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

2007-01-05

The use of methanol-aqueous buffer mobile phases in HPLC is a common election when performing chromatographic separations of ionisable analytes. The addition of methanol to the aqueous buffer to prepare such a mobile phase changes the buffer capacity and the pH of the solution. In the present work, the variation of these buffer properties is studied for acetic acid-acetate, phosphoric acid-dihydrogenphosphate-hydrogenphosphate, citric acid-dihydrogencitrate-hydrogencitrate-citrate, and ammonium-ammonia buffers. It is well established that the pH change of the buffers depends on the initial concentration and aqueous pH of the buffer, on the percentage of methanol added, and on the particular buffer used. The proposed equations allow the pH estimation of methanol-water buffered mobile phases up to 80% in volume of organic modifier from initial aqueous buffer pH and buffer concentration (before adding methanol) between 0.001 and 0.01 mol L(-1). From both the estimated pH values of the mobile phase and the estimated pKa of the ionisable analytes, it is possible to predict the degree of ionisation of the analytes and therefore, the interpretation of acid-base analytes behaviour in a particular methanol-water buffered mobile phase.

EXTRACTION OF URANYL NITRATE FROM AQUEOUS SOLUTIONS

Science.gov (United States)

Furman, N.H.; Mundy, R.J.

1957-12-10

An improvement in the process is described for extracting aqueous uranyl nitrate solutions with an organic solvent such as ether. It has been found that the organic phase will extract a larger quantity of uranyl nitrate if the aqueous phase contains in addition to the uranyl nitrate, a quantity of some other soluble nitrate to act as a salting out agent. Mentioned as suitable are the nitrates of lithium, calcium, zinc, bivalent copper, and trivalent iron.

Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols

Directory of Open Access Journals (Sweden)

M. M. Chim

2017-12-01

Full Text Available Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C5H8O4 droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C5 hydroxyl functionalization product (C5H8O5 and a C4 fragmentation product (C4H6O3. These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon–carbon bond scission of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model coupled with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from

Propagation of the Semidiurnal Internal Tide: Phase Velocity Versus Group Velocity

Science.gov (United States)

Zhao, Zhongxiang

2017-12-01

The superposition of two waves of slightly different wavelengths has long been used to illustrate the distinction between phase velocity and group velocity. The first-mode M2 and S2 internal tides exemplify such a two-wave model in the natural ocean. The M2 and S2 tidal frequencies are 1.932 and 2 cycles per day, respectively, and their superposition forms a spring-neap cycle in the semidiurnal band. The spring-neap cycle acts like a wave, with its frequency, wave number, and phase being the differences of the M2 and S2 internal tides. The spring-neap cycle and energy of the semidiurnal internal tide propagate at the group velocity. Long-range propagation of M2 and S2 internal tides in the North Pacific is observed by satellite altimetry. Along a 3,400 km beam spanning 24°-54°N, the M2 and S2 travel times are 10.9 and 11.2 days, respectively. For comparison, it takes the spring-neap cycle 21.1 days to travel over this distance. Spatial maps of the M2 phase velocity, the S2 phase velocity, and the group velocity are determined from phase gradients of the corresponding satellite observed internal tide fields. The observed phase and group velocities agree with theoretical values estimated using the World Ocean Atlas 2013 annual-mean ocean stratification.

Separation of tritium from gaseous and aqueous effluent systems

International Nuclear Information System (INIS)

Kobisk, E.H.

1977-01-01

Three processes are discussed for separating tritium from gaseous and aqueous effluent systems: separation in the gas phase using Pd-25 wt percent Ag alloy diffusion membranes; electrolytic separation in the aqueous phase using ''bipolar'' electrodes; and the countercurrent exchange of tritium-containing hydrogen gas with water on catalytic surfaces combined with separation by direct electrolysis

Phase equilibria in a system of aqueous arginine with an octane solution of sulfonic acid

Science.gov (United States)

Kuvaeva, Z. I.; Koval'chuk, I. V.; Vodop'yanova, L. A.; Soldatov, V. S.

2013-05-01

The extraction of arginine (Arg) from aqueous salt (0.1 M NaCl) solutions with a sulfo extractant in a wide range of pH values and amino acid concentrations was studied. The 0.1 M solution of dinonylnaphthalenesulfonic acid (HD) in octane was used as an extractant. The degree of extraction was found to be high at pH 0.8-9.0. This can be explained by the effect of additional intermolecular interactions in the extractant phase involving the guanidine group of Arg.

SU119. Internalized Stigma in Adults With Early-Phase vs Prolonged Psychosis

Science.gov (United States)

Firmin, Ruth; Vohs, Jenifer; Luther, Lauren; Yanos, Philip; Leonhardt, Bethany; Lysaker, Paul

2017-01-01

Abstract Background: While internalized stigma is associated with negative outcomes among those with prolonged psychosis, surprisingly little work has focused on when in the course of one’s illness stigma is internalized and the impact of internalization on symptoms or quality of life over the course of the illness. Therefore, this study investigated whether (1) internalized stigma is greater among those later in the course of psychosis and (2) whether internalized stigma has a stronger negative relationship with quality of life or symptoms among those with prolonged compared to early-phase psychosis. Methods: Individuals with early-phase (n = 40) and prolonged psychosis (n = 71) who were receiving outpatient services at an early-intervention clinic and a VA medical center, respectively, completed self-report measures of internalized stigma and interview-rated measures of symptoms and quality of life. Results: Controlling for education, race, and sex differences, internalized stigma was significantly greater among those with prolonged compared to early-phase psychosis. Internalized stigma was negatively related to quality of life and positively related to symptoms in both groups. Furthermore, the magnitude of the relationship between cognitive symptoms and internalized stigma was significantly greater among those with early-phase psychosis. Stereotype endorsement, discrimination experiences, and social withdrawal also deferentially related to symptoms and quality of life across the 2 samples. Conclusion: Findings suggest that internalized stigma is an important variable to incorporate into models of early psychosis. Further, internalized stigma may be a possible treatment target among those in their early phase of psychosis.

Use of microalgae to recycle nutrients in aqueous phase derived from hydrothermal liquefaction process.

Science.gov (United States)

Leng, Lijian; Li, Jun; Wen, Zhiyou; Zhou, Wenguang

2018-05-01

Hydrothermal liquefaction (HTL) of microalgae biomass generates an aqueous phase (AP) byproduct with limited energy value. Recycling the AP solution as a source of nutrients for microalgae cultivation provides an opportunity for a cost-effective production of HTL based biofuel and algal biomass feedstock for HTL, allowing a closed-loop biofuel production in microalgae HTL biofuel system. This paper aims to provide a comprehensive overview of characteristics of AP and its nutrients recycling for algae production. Inhibitory effects resulted from the toxic compounds in AP and alleviation strategies are discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydroxyapatite-based sorbents: elaboration, characterization and application for the removal of catechol from the aqueous phase.

Science.gov (United States)

Sebei, Haroun; Pham Minh, Doan; Lyczko, Nathalie; Sharrock, Patrick; Nzihou, Ange

2017-10-01

Hydroxyapatite (HAP) is highly considered as good sorbent for the removal of metals from the aqueous phase. However, soluble metals co-exist with organic pollutants in wastewaters. But little work has been devoted to investigate the reactivity of HAP for the removal of organic compounds. The main objective of this work is to study the reactivity of HAP-based sorbents for the removal of catechol as a model organic pollutant from an aqueous solution. Thus, HAP sorbents were firstly synthesized using calcium carbonate and potassium dihydrogen phosphate under moderate conditions (25-80°C, atmospheric pressure). A zinc-doped HAP was also used as sorbent, which was obtained from the contact of HAP with an aqueous solution of zinc nitrate. All the sorbents were characterized by different standard physico-chemical techniques. The sorption of catechol was carried out in a batch reactor under stirring at room temperature and pressure. Zinc-doped HAP sorbent was found to be more reactive than non-doped HAP sorbents for the fixation of catechol. The highest sorption capacity was of 15 mg of C per gram of zinc-doped HAP sorbent. The results obtained suggest the reaction scheme of HAP sorbents with metals and organic pollutants when HAP sorbents were used for the treatment of complex wastewaters.

Aqueous two-phase extraction as a platform in the biomanufacturing industry: economical and environmental sustainability.

Science.gov (United States)

Rosa, P A J; Azevedo, A M; Sommerfeld, S; Bäcker, W; Aires-Barros, M R

2011-01-01

The biotech industry is, nowadays, facing unparalleled challenges due to the enhanced demand for biotechnology-based human therapeutic products, such as monoclonal antibodies (mAbs). This has led companies to improve substantially their upstream processes, with the yield of monoclonals increasing to titers never seen before. The downstream processes have, however, been overlooked, leading to a production bottleneck. Although chromatography remains the workhorse of most purification processes, several limitations, such as low capacity, scale-related packing problems, low chemical and proteolytic stability and resins' high cost, have arisen. Aqueous two-phase extraction (ATPE) has been successfully revisited as a valuable alternative for the capture of antibodies. One of the important remaining questions for this technology to be adopted by the biotech industries is, now, how it compares to the currently established platforms in terms of costs and environmental impact. In this report, the economical and environmental sustainability of the aqueous two-phase extraction process is evaluated and compared to the currently established protein A affinity chromatography. Accordingly, the ATPE process was shown to be considerably advantageous in terms of process economics, especially when processing high titer cell culture supernatants. This alternative process is able to purify continuously the same amount of mAbs reducing the annual operating costs from 14.4 to 8.5 million (US$/kg) when cell culture supernatants with mAb titers higher than 2.5 g/L are processed. Copyright © 2011 Elsevier Inc. All rights reserved.

[DNA complexes, formed on aqueous phase surfaces: new planar polymeric and composite nanostructures].

Science.gov (United States)

Antipina, M N; Gaĭnutdinov, R V; Rakhnianskaia, A A; Sergeev-Cherenkov, A N; Tolstikhina, A L; Iurova, T V; Kislov, V V; Khomutov, G B

2003-01-01

The formation of DNA complexes with Langmuir monolayers of the cationic lipid octadecylamine (ODA) and the new amphiphilic polycation poly-4-vinylpyridine with 16% of cetylpyridinium groups (PVP-16) on the surface of an aqueous solution of native DNA of low ionic strength was studied. Topographic images of Langmuir-Blodgett films of DNA/ODA and DNA/PVP-16 complexes applied to micaceous substrates were investigated by the method of atomic force microscopy. It was found that films of the amphiphilic polycation have an ordered planar polycrystalline structure. The morphology of planar DNA complexes with the amphiphilic cation substantially depended on the incubation time and the phase state of the monolayer on the surface of the aqueous DNA solution. Complex structures and individual DNA molecules were observed on the surface of the amphiphilic monolayer. Along with quasi-linear individual bound DNA molecules, characteristic extended net-like structures and quasi-circular toroidal condensed conformations of planar DNA complexes were detected. Mono- and multilayer films of DNA/PVP-16 complexes were used as templates and nanoreactors for the synthesis of inorganic nanostructures via the binding of metal cations from the solution and subsequent generation of the inorganic phase. As a result, ultrathin polymeric composite films with integrated DNA building blocks and quasi-linear arrays of inorganic semiconductor (CdS) and iron oxide nanoparticles and nanowires were obtained. The nanostructures obtained were characterized by scanning probe microscopy and transmission electron microscopy techniques. The methods developed are promising for investigating the mechanisms of structural organization and transformation in DNA and polyelectrolyte complexes at the gas-liquid interface and for the design of new extremely thin highly ordered planar polymeric and composite materials, films, and coatings with controlled ultrastructure for applications in nanoelectronics and

Characterisation and final disposal behaviour of theoria-based fuel kernels in aqueous phases

International Nuclear Information System (INIS)

Titov, M.

2005-08-01

Two high-temperature reactors (AVR and THTR) operated in Germany have produced about 1 million spent fuel elements. The nuclear fuel in these reactors consists mainly of thorium-uranium mixed oxides, but also pure uranium dioxide and carbide fuels were tested. One of the possible solutions of utilising spent HTR fuel is the direct disposal in deep geological formations. Under such circumstances, the properties of fuel kernels, and especially their leaching behaviour in aqueous phases, have to be investigated for safety assessments of the final repository. In the present work, unirradiated ThO 2 , (Th 0.906 ,U 0.094 )O 2 , (Th 0.834 ,U 0.166 )O 2 and UO 2 fuel kernels were investigated. The composition, crystal structure and surface of the kernels were investigated by traditional methods. Furthermore, a new method was developed for testing the mechanical properties of ceramic kernels. The method was successfully used for the examination of mechanical properties of oxide kernels and for monitoring their evolution during contact with aqueous phases. The leaching behaviour of thoria-based oxide kernels and powders was investigated in repository-relevant salt solutions, as well as in artificial leachates. The influence of different experimental parameters on the kernel leaching stability was investigated. It was shown that thoria-based fuel kernels possess high chemical stability and are indifferent to presence of oxidative and radiolytic species in solution. The dissolution rate of thoria-based materials is typically several orders of magnitude lower than of conventional UO 2 fuel kernels. The life time of a single intact (Th,U)O 2 kernel under aggressive conditions of salt repository was estimated as about hundred thousand years. The importance of grain boundary quality on the leaching stability was demonstrated. Numerical Monte Carlo simulations were performed in order to explain the results of leaching experiments. (orig.)

A thermodynamic model for aqueous solutions of liquid-like density

Energy Technology Data Exchange (ETDEWEB)

Pitzer, K.S.

1987-06-01

The paper describes a model for the prediction of the thermodynamic properties of multicomponent aqueous solutions and discusses its applications. The model was initially developed for solutions near room temperature, but has been found to be applicable to aqueous systems up to 300/sup 0/C or slightly higher. A liquid-like density and relatively small compressibility are assumed. A typical application is the prediction of the equilibrium between an aqueous phase (brine) and one or more solid phases (minerals). (ACR)

Lactose hydrolysis in aqueous two-phase system by whole-cell {beta}-galactosidase of Kluyveromyces marxianus. Semicontinuous and continuous processes

Energy Technology Data Exchange (ETDEWEB)

Tomaska, M [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology; Stredansky, M [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology; Tomaskova, A [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology; Sturdik, E [Slovak Technical Univ., Bratislava (Slovakia). Dept. of Biochemical Technology

1995-01-01

Semicontinuous and continuous hydrolysis of lactose in aqueous two-phase systems (polyethylene glycol 20000/ dextran 40) with whole-cell {beta}-galactosidase of K. marxianus were studied. Both phase polymers had no effect on {beta}-galactosidase activity confined in cells. Good operational stability of the biocatalyst during 55 cycles of semicontinuous process was observed without appreciable decrease in product concentration. Continuous hydrolysis of lactose was performed in the stirred bioreactor, connected with the phase separator. The satisfactory degree of hydrolysis (between 82-88%) and volumetric productivity (21.6 g/l/h) were reached during 72 hours of continuous hydrolysis of 5% (w/w) lactose. (orig.)

Extraction of ascorbate oxidase from Cucurbita maxima by continuous process in perforated rotating disc contactor using aqueous two-phase systems.

Science.gov (United States)

Porto, T S; Marques, P P; Porto, C S; Moreira, K A; Lima-Filho, J L; Converti, A; Pessoa, A; Porto, A L F

2010-02-01

The ascorbate oxidase is the enzyme used to determine the content of ascorbic acid in the pharmaceutical and food industries and clinics analyses. The techniques currently used for the purification of this enzyme raise its production cost. Thus, the development of alternative processes and with the potential to reduce costs is interesting. The application of aqueous two-phase system is proposed as an alternative to purification because it enables good separation of biomolecules. The objective of this study was to determine the conditions to continuously pre-purify the enzyme ascorbate oxidase by an aqueous two-phase system (PEG/citrate) using rotating column provided with perforated discs. Under the best conditions (20,000 g/mol PEG molar mass, 10% PEG concentration, and 25% citrate concentration), the system showed satisfactory results (partition coefficient, 3.35; separation efficiency, 54.98%; and purification factor, 1.46) and proved suitable for the pre-purification of ascorbate oxidase in continuous process.

Crystalline phase, microstructure, and aqueous stability of zirconolite-barium borosilicate glass-ceramics for immobilization of simulated sulfate bearing high-level liquid waste

Science.gov (United States)

Wu, Lang; Xiao, Jizong; Wang, Xin; Teng, Yuancheng; Li, Yuxiang; Liao, Qilong

2018-01-01

The crystalline phase, microstructure, and aqueous stability of zirconolite-barium borosilicate glass-ceramics with different content (0-30 wt %) of simulated sulfate bearing high-level liquid waste (HLLW) were evaluated. The sulfate phase segregation in vitrification process was also investigated. The results show that the glass-ceramics with 0-20 wt% of HLLW possess mainly zirconolite phase along with a small amount baddeleyite phase. The amount of perovskite crystals increases while the amount of zirconolite crystals decreases when the HLLW content increases from 20 to 30 wt%. For the samples with 20-30 wt% HLLW, yellow phase was observed during the vitrification process and it disappeared after melting at 1150 °C for 2 h. The viscosity of the sample with 16 wt% HLLW (HLLW-16) is about 27 dPa·s at 1150 °C. The addition of a certain amount (≤20 wt %) of HLLW has no significant change on the aqueous stability of glass-ceramic waste forms. After 28 days, the 90 °C PCT-type normalized leaching rates of Na, B, Si, and La of the sample HLLW-16 are 7.23 × 10-3, 1.57 × 10-3, 8.06 × 10-4, and 1.23 × 10-4 g·m-2·d-1, respectively.

Affinity partitioning of human antibodies in aqueous two-phase systems.

Science.gov (United States)

Rosa, P A J; Azevedo, A M; Ferreira, I F; de Vries, J; Korporaal, R; Verhoef, H J; Visser, T J; Aires-Barros, M R

2007-08-24

The partitioning of human immunoglobulin (IgG) in a polymer-polymer and polymer-salt aqueous two-phase system (ATPS) in the presence of several functionalised polyethylene glycols (PEGs) was studied. As a first approach, the partition studies were performed with pure IgG using systems in which the target protein remained in the bottom phase when the non-functionalised systems were tested. The effect of increasing functionalised PEG concentration and the type of ligand were studied. Afterwards, selectivity studies were performed with the most successful ligands first by using systems containing pure proteins and an artificial mixture of proteins and, subsequently, with systems containing a Chinese hamster ovary (CHO) cells supernatant. The PEG/phosphate ATPS was not suitable for the affinity partitioning of IgG. In the PEG/dextran ATPS, the diglutaric acid functionalised PEGs (PEG-COOH) displayed great affinity to IgG, and all IgG could be recovered in the top phase when 20% (w/w) of PEG 150-COOH and 40% (w/w) PEG 3350-COOH were used. The selectivity of these functionalised PEGs was evaluated using an artificial mixture of proteins, and PEG 3350-COOH did not show affinity to IgG in the presence of typical serum proteins such as human serum albumin and myoglobin, while in systems with PEG 150-COOH, IgG could be recovered with a yield of 91%. The best purification of IgG from the CHO cells supernatant was then achieved in a PEG/dextran ATPS in the presence of PEG 150-COOH with a recovery yield of 93%, a purification factor of 1.9 and a selectivity to IgG of 11. When this functionalised PEG was added to the ATPS, a 60-fold increase in selectivity was observed when compared to the non-functionalised systems.

Experimental determination and thermodynamic modeling of phase equilibrium and protein partitioning in aqueous two-phase systems containing biodegradable salts

International Nuclear Information System (INIS)

Perez, Brenda; Malpiedi, Luciana Pellegrini; Tubío, Gisela; Nerli, Bibiana; Alcântara Pessôa Filho, Pedro de

2013-01-01

Highlights: ► Binodal data of systems (water + polyethyleneglycol + sodium) succinate are reported. ► Pitzer model describes the phase equilibrium of systems formed by polyethyleneglycol and biodegradable salts satisfactorily. ► This simple thermodynamic framework was able to predict the partitioning behaviour of model proteins acceptably well. - Abstract: Phase diagrams of sustainable aqueous two-phase systems (ATPSs) formed by polyethyleneglycols (PEGs) of different average molar masses (4000, 6000, and 8000) and sodium succinate are reported in this work. Partition coefficients (Kps) of seven model proteins: bovine serum albumin, catalase, beta-lactoglobulin, alpha-amylase, lysozyme, pepsin, urease and trypsin were experimentally determined in these systems and in ATPSs formed by the former PEGs and other biodegradable sodium salts: citrate and tartrate. An extension of Pitzer model comprising long and short-range term contributions to the excess Gibbs free energy was used to describe the (liquid + liquid) equilibrium. Comparison between experimental and calculated tie line data showed mean deviations always lower than 3%, thus indicating a good correlation. The partition coefficients were modeled by using the same thermodynamic approach. Predicted and experimental partition coefficients correlated quite successfully. Mean deviations were found to be lower than the experimental uncertainty for most of the assayed proteins.

RAMAN SPECTRA OF AQUEOUS FLUID INCLUSIONS: EFFECT OF MINERAL BIREFRINGENCE AND METASTABILITY ON SALINITY MEASUREMENT

OpenAIRE

Caumon , Marie-Camille; Tarantola , Alexandre

2014-01-01

International audience; Introduction: Crustal fluids play a major role in ore deposits, basin diagenesis and metamorphic reactions, among others. The knowledge of the chemical composition of individual fluid inclusions is essential for the understanding of past fluid transport and circulations. Microthermometry, by the observation of specific phase transitions as a function of temperature, is the general approach to determine salinity in aqueous fluid inclusions [1]. However in some cases, th...

Aqueous two-phase system patterning of detection antibody solutions for cross-reaction-free multiplex ELISA

Science.gov (United States)

Frampton, John P.; White, Joshua B.; Simon, Arlyne B.; Tsuei, Michael; Paczesny, Sophie; Takayama, Shuichi

2014-05-01

Accurate disease diagnosis, patient stratification and biomarker validation require the analysis of multiple biomarkers. This paper describes cross-reactivity-free multiplexing of enzyme-linked immunosorbent assays (ELISAs) using aqueous two-phase systems (ATPSs) to confine detection antibodies at specific locations in fully aqueous environments. Antibody cross-reactions are eliminated because the detection antibody solutions are co-localized only to corresponding surface-immobilized capture antibody spots. This multiplexing technique is validated using plasma samples from allogeneic bone marrow recipients. Patients with acute graft versus host disease (GVHD), a common and serious condition associated with allogeneic bone marrow transplantation, display higher mean concentrations for four multiplexed biomarkers (HGF, elafin, ST2 and TNFR1) relative to healthy donors and transplant patients without GVHD. The antibody co-localization capability of this technology is particularly useful when using inherently cross-reactive reagents such as polyclonal antibodies, although monoclonal antibody cross-reactivity can also be reduced. Because ATPS-ELISA adapts readily available antibody reagents, plate materials and detection instruments, it should be easily transferable into other research and clinical settings.

IONS FROM AQUEOUS PHASE BY WATER HYACINTH (Eichhornia

African Journals Online (AJOL)

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Most often there is incomplete metal ion removal, high reagent and ... environmentally friendly water filters for heavy metal ions removal in aqueous systems. Currently E. crassipes is ..... From the results, the singly charged ions have very little ...

Physical and chemical interactions at the interface between atmospheric pressure plasmas and aqueous solutions

Science.gov (United States)

Lindsay, Alexander; Byrns, Brandon; Knappe, Detlef; Graves, David; Shannon, Steven

2014-10-01

Transport and reactions of charged species, neutrals, and photons at the interface between plasmas and liquids must be better quantified. The work presented here combines theoretical and experimental investigations of conditions in the gas and liquid phases in proximity to the interface for various discharges. OES is used to determine rotational and vibrational temperatures of OH, NO, and N2+; the relationship between these temperatures that characterize the distribution of internal energy states and gas and electron kinetic temperatures is considered. The deviation of OH rotational states from equilibrium under high humidity conditions is also presented. In contradiction with findings of other groups, high energy rotational states appear to become underpopulated with increasing humidity. In the aqueous phase, concentrations of longer-lived species such as nitrate, nitrite, hydrogen peroxide, and ozone are determined using ion chromatography and colorimetric methods. Spin-traps and electron paramagnetic resonance (EPR) are investigated for characterization of short-lived aqueous radicals like OH, O2-, NO, and ONOO-. Finally, experimental results are compared to a numerical model which couples transport and reactions within and between the bulk gas and liquid phases.

Phase equilibrium of (CO2 + 1-aminopropyl-3-methylimidazolium bromide + water) electrolyte system and effects of aqueous medium on CO2 solubility: Experiment and modeling

International Nuclear Information System (INIS)

Chen, Ying; Guo, Kaihua; Bi, Yin; Zhou, Lan

2017-01-01

Highlights: • Phase and chemical equilibrium data for (CO 2 + [APMIm]Br + H 2 O) electrolyte system. • A modified eNRTL model for CO 2 solubility in the amino-based IL aqueous solution. • Effects of aqueous medium on both chemical and physical dissolution of CO 2 . • The correlative coefficient, R s ∗ , for the Henry’s constant of the solution. • New parameters for the segments interaction and the chemical equilibrium constants. - Abstract: New experimental data for solubility of carbon dioxide (CO 2 ) in the aqueous solution of 1-aminopropyl-3-methylimidazolium bromide ([APMIm]Br) with four different water mass fractions (0.559, 0.645, 0.765 and 0.858) at T = (278.15–348.15) K with an interval of T = 10 K and p = (0.1237–6.9143) MPa were presented. The electrolyte nonrandom two-liquid (eNRTL) model was modified to be applicable for an ionic liquid (IL) aqueous solution system, by introducing an idle factor β to illustrate the association effect of IL molecules. A solution Henry’s constant for CO 2 solubility in the IL aqueous solution was defined by introducing a correlative coefficient R s ∗ . The vapor-liquid phase equilibrium of the [APMIm]Br-H 2 O-CO 2 ternary system was successfully calculated with the modified eNRTL model. The chemical and physical mechanisms for the ionized CO 2 formation and the molecular CO 2 dissolved in the solution were identified. The effects of aqueous medium on both chemical and physical dissolution of CO 2 in the [APMIm]Br aqueous solution were studied, and a considerable enhancement of the solubility of CO 2 with increase of the water content in the solution was observed.

Small GSH-Capped CuInS2 Quantum Dots: MPA-Assisted Aqueous Phase Transfer and Bioimaging Applications.

Science.gov (United States)

Zhao, Chuanzhen; Bai, Zelong; Liu, Xiangyou; Zhang, Yijia; Zou, Bingsuo; Zhong, Haizheng

2015-08-19

An efficient ligand exchange strategy for aqueous phase transfer of hydrophobic CuInS2/ZnS quantum dots was developed by employing glutathione (GSH) and mercaptopropionic acid (MPA) as the ligands. The whole process takes less than 20 min and can be scaled up to gram amount. The material characterizations show that the final aqueous soluble samples are solely capped with GSH on the surface. Importantly, these GSH-capped CuInS2/ZnS quantum dots have small size (hydrodynamic diameter quantum dots, for instance, CuInSe2 and CdSe/ZnS quantum dots. We further demonstrated that GSH-capped quantum dots could be suitable fluorescence markers to penetrate cell membrane and image the cells. In addition, the GSH-capped CuInS2 quantum dots also have potential use in other fields such as photocatalysis and quantum dots sensitized solar cells.

Liquid-liquid transfer phenomena studies coupled with redox reactions: back-extraction of nitrous acid in the presence of scavengers in aqueous phase

International Nuclear Information System (INIS)

K'zerho, R.

1998-01-01

This work deals with the investigation of redox reaction contribution to the kinetics of liquid-liquid transfer, in relation with PUREX reprocessing of spent nuclear fuel. The chemical system chosen concerns the tripping of nitrous acid from tributylphosphate organic phase into a nitric acid aqueous solution containing an 'anti-nitrous' component, namely hydrazinium nitrate. According to the abundant literature, a major attention is devoted to the very important role of interfacial phenomena on the kinetics of solvent extraction with tributylphosphate. Although, a suitable experimental technique is chosen, using a constant interfacial area cell of the ARMOLLEX-type. Furthermore, the effects of the hydrodynamical and the physico-chemical parameters on the extraction rate led to the identification of the extraction regime nature: diffusional, then chemical limitation. When no 'anti-nitrous' component is used, the diffusional resistance is found to be mainly located in the aqueous diffusion layer. The presence of hydrazinium nitrate into the aqueous solution has an overall accelerating effect on the rate of extraction, related to both a complete suppression of the aqueous diffusional resistance, and a very significant enhancement of the interfacial transfer of the nitrous acid, as a function of hydrazinium concentration. If the first effect could be expected because of the well known fast redox reaction in aqueous phase, the second phenomenon represents a quite original and new result which has never been explored before, to the best of our knowledge. A reaction mechanism is postulated and validated, taking into account the reactive effect of hydrazinium on the interfacial step. In order to support the drawn general patterns, different complementary studies were attempted. When hydroxyl-ammonium nitrate is used, a surprising interfacial transfer blockage is observed, pointing out the extreme performance and specificity of the common hydrazinium component. (author)

Refinement of Modeled Aqueous-Phase Sulfate Production via the Fe- and Mn-Catalyzed Oxidation Pathway

Directory of Open Access Journals (Sweden)

Syuichi Itahashi

2018-04-01

Full Text Available We refined the aqueous-phase sulfate (SO42− production in the state-of-the-art Community Multiscale Air Quality (CMAQ model during the Japanese model inter-comparison project, known as Japan’s Study for Reference Air Quality Modeling (J-STREAM. In Japan, SO42− is the major component of PM2.5, and CMAQ reproduces the observed seasonal variation of SO42− with the summer maxima and winter minima. However, CMAQ underestimates the concentration during winter over Japan. Based on a review of the current modeling system, we identified a possible reason as being the inadequate aqueous-phase SO42− production by Fe- and Mn-catalyzed O2 oxidation. This is because these trace metals are not properly included in the Asian emission inventories. Fe and Mn observations over Japan showed that the model concentrations based on the latest Japanese emission inventory were substantially underestimated. Thus, we conducted sensitivity simulations where the modeled Fe and Mn concentrations were adjusted to the observed levels, the Fe and Mn solubilities were increased, and the oxidation rate constant was revised. Adjusting the concentration increased the SO42− concentration during winter, as did increasing the solubilities and revising the rate constant to consider pH dependencies. Statistical analysis showed that these sensitivity simulations improved model performance. The approach adopted in this study can partly improve model performance in terms of the underestimation of SO42− concentration during winter. From our findings, we demonstrated the importance of developing and evaluating trace metal emission inventories in Asia.

Determination of ammonium in aqueous samples using new headspace dynamic in-syringe liquid-phase microextraction with in situ derivitazation coupled with liquid chromatography-fluorescence detection.

Science.gov (United States)

Muniraj, Sarangapani; Yan, Cheing-Tong; Shih, Hou-Kung; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

2012-11-19

A new simultaneous derivatization and extraction method for the preconcentration of ammonia using new one-step headspace dynamic in-syringe liquid-phase microextraction with in situ derivatization was developed for the trace determination of ammonium in aqueous samples by liquid chromatography with fluorescence detection (LC-FLD). The acceptor phase (as derivatization reagent) containing o-phthaldehyde and sodium sulfite was held within a syringe barrel and immersed in the headspace of sample container. The gaseous ammonia from the alkalized aqueous sample formed a stable isoindole derivative with the acceptor phase inside the syringe barrel through the reciprocated movements of plunger. After derivatization-cum-extraction, the acceptor phase was directly injected into LC-FLD for analysis. Parameters affecting the ammonia evolution and the extraction/derivatization efficiency such as sample matrix, pH, temperature, sampling time, and the composition of derivatization reagent, reaction temperature, and frequency of reciprocated plunger, were studied thoroughly. Results indicated that the maximum extraction efficiency was obtained by using 100μL derivatization reagent in a 1-mL gastight syringe under 8 reciprocated movements of plunger per min to extract ammonia evolved from a 20mL alkalized aqueous solution at 70°C (preheated 4min) with 380rpm stirring for 8min. The detection was linear in the concentration range of 0.625-10μM with the correlation coefficient of 0.9967 and detection limit of 0.33μM (5.6ng mL(-1)) based on SN(-1)=3. The method was applied successfully to determine ammonium in real water samples without any prior cleanup of the samples, and has been proved to be a simple, sensitive, efficient and cost-effective procedure for trace ammonium determination in aqueous samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of heavy polycyclic aromatic hydrocarbons by non-aqueous reversed phase liquid chromatography: Application and limitation in refining streams.

Science.gov (United States)

Panda, Saroj K; Muller, Hendrik; Al-Qunaysi, Thunayyan A; Koseoglu, Omer R

2018-01-19

The heavy polycyclic aromatic hydrocarbons (HPAHs) cause detrimental effects to hydrocracker operations by deactivating the catalysts and depositing in the downstream of the reactor/ exchangers. Therefore, it is essential to continuously monitor the accumulation of HPAHs in a hydrocracker unit. To accurately measure the concentration of HPAHs, the development of a fast and reliable analytical method is inevitable. In this work, an analytical method based on non-aqueous reversed phase chromatography in combination with high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was developed. As a first step, five different types of stationary phases were evaluated for the separation of HPAHs in non-aqueous mode and the best suited phase was further used for the fractionation of HPAHs in a fractionator bottom sample obtained from a refinery hydrocracker unit. The eight major fractions or peaks obtained from the separation were further characterized by UV spectroscopy and FT-ICR MS and the compounds in the fractions were tentatively confirmed as benzoperylene, coronene, methylcoronene, naphthenocoronene, benzocoronene, dibenzoperylene, naphthocoronene and ovalene. The developed liquid chromatography method can be easily adapted in a refinery laboratory for the quantitation of HPAHs in hydrocracking products. The method was further tested to check the interference of sulfur aromatics and/or large alkylated aromatic hydrocarbons on the determination of HPAHs in hydrocracking products. Copyright © 2017 Elsevier B.V. All rights reserved.

Cheese whey valorisation: Production of valuable gaseous and liquid chemicals from lactose by aqueous phase reforming

International Nuclear Information System (INIS)

Remón, J.; Ruiz, J.; Oliva, M.; García, L.; Arauzo, J.

2016-01-01

Highlights: • Aqueous phase reforming: a promising strategy for cheese whey valorisation. • In-depth understanding of the effect of the operating conditions on the process. • Process optimisation for the selective production of valuable gas and liquid products. • High P, T, lactose concentration and spatial time favour gas production. • High T, low spatial time and the use of diluted solutions maximise liquids production. - Abstract: Cheese effluent management has become an important issue owing to its high biochemical oxygen demand and chemical oxygen demand values. Given this scenario, this work addresses the valorisation of lactose (the largest organic constituent of this waste) by aqueous phase reforming, analysing the influence of the most important operating variables (temperature, pressure, lactose concentration and mass of catalyst/lactose mass flow rate ratio) as well as optimising the process for the production of either gaseous or liquid value-added chemicals. The carbon converted into gas, liquid and solid products varied as follows: 5–41%, 33–97% and 0–59%, respectively. The gas phase was made up of a mixture of H_2 (8–58 vol.%), CO_2 (33–85 vol.%), CO (0–15 vol.%) and CH_4 (0–14 vol.%). The liquid phase consisted of a mixture of aldehydes: 0–11%, carboxylic acids: 0–22%, monohydric alcohols: 0–23%, polyhydric-alcohols: 0–48%, C3-ketones: 4–100%, C4-ketones: 0–18%, cyclic-ketones: 0–15% and furans: 0–85%. H_2 production is favoured at high pressure, elevated temperature, employing a high amount of catalyst and a concentrated lactose solution. Liquid production is preferential using diluted lactose solutions. At high pressure, the production of C3-ketones is preferential using a high temperature and a low amount of catalyst, while a medium temperature and a high amount of catalyst favours the production of furans. The production of alcohols is preferential using medium temperature and pressure and a low amount of

Metal separations using aqueous biphasic partitioning systems

International Nuclear Information System (INIS)

Chaiko, D.J.; Zaslavsky, B.; Rollins, A.N.; Vojta, Y.; Gartelmann, J.; Mego, W.

1996-01-01

Aqueous biphasic extraction (ABE) processes offer the potential for low-cost, highly selective separations. This countercurrent extraction technique involves selective partitioning of either dissolved solutes or ultrafine particulates between two immiscible aqueous phases. The extraction systems that the authors have studied are generated by combining an aqueous salt solution with an aqueous polymer solution. They have examined a wide range of applications for ABE, including the treatment of solid and liquid nuclear wastes, decontamination of soils, and processing of mineral ores. They have also conducted fundamental studies of solution microstructure using small angle neutron scattering (SANS). In this report they review the physicochemical fundamentals of aqueous biphase formation and discuss the development and scaleup of ABE processes for environmental remediation

Solvent extraction separations of trivalent lanthanide and actinide ions using an aqueous aminomethanediphosphonic acid

International Nuclear Information System (INIS)

Jensen, M. P.

1998-01-01

The possibility of separating the trivalent lanthanides, represented by EU 3+ , and actinides, represented by Cf 3+ , using HDEHP in toluene and an aqueous phase containing N-piperidinomethane-1,1-diphosphotic acid, PMDPA, has been investigated. This modified aqueous phase offers potential advantages over the diethylenetriaminepentaacetic acid based TALSPEAK process because of the improved complexation properties of PMDPA in acidic solutions, and the ability to decompose PMDPA before disposal. Extraction experiments were conducted at 25 C in 2 M NaClO 4 between -log [H + ] 1 and 2. The studies enabled us to derive the aqueous phase speciation, the stability constants of the aqueous complexes, and the Cf/Eu separation factors. Despite the presence of an amino group in PMDPA that should favor the retention of the actinides in the aqueous phase, the Cf/Eu separation factors are near unity under the conditions studied

Aqueous two-phase system purification for superoxide dismutase induced by menadione from Phanerochaete chrysosporium.

Science.gov (United States)

Kavakcıoğlu, Berna; Tongul, Burcu; Tarhan, Leman

2017-03-01

In the present work, the partitioning behavior of menadione-induced superoxide dismutase (SOD; EC 1.15.1.1), an antioxidant enzyme that has various applications in the medical and cosmetic industries, from the white rot fungus Phanerochaete chrysosporium has been characterized on different types of aqueous two-phase systems (ATPSs) (poly(ethylene glycol)/polypropylene glycol (PEG/PPG)-dextran, PEG-salt and PPG-salt). PEG-salt combinations were found most optimal systems for the purification of SOD. The best partition conditions were found using the PEG-3350 24% and K 2 HPO 4 5% (w/w) with pH 7.0 at 25 °C. The partition coefficient of total SOD activity and total protein concentration observed in this system were 0.17 and 6.65, respectively, with the recovery percentage as 78.90% in the bottom phase and 13.17% in the top phase. The highest purification fold for SOD from P. chrysosporium was found as 6.04 in the bottom phase of PEG 3350%24 - K 2 HPO 4 %5 (w/w) system with pH 7.0. SOD purified from P. chrysosporium was determined to be a homodimer in its native state with a molecular weight of 60  ± 4 kDa. Consequently, simple and only one step PEG-salt ATPS system was developed for SOD purification from P. chrysosporium.

Determination of Dibenzacridines in the Particulate Phase of Cigarette Smoke

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Sasaki TA

2014-12-01

Full Text Available This study attempted to resolve a controversy related to the presence of dibenz[a,j]acridine and dibenz[a,h]acridine in the particulate phase of cigarette smoke. Smoking was performed using FTC conditions (35 mL puff volume, 2 sec. puff, 1 min. interval on a Borgwaldt RM 20/CS smoking machine. The particulate phase of forty cigarettes was collected on 92 mm Cambridge filter pads. Pads were combined to analyze the particulate phase of the mainstream smoke from between 120 and 320 cigarettes. In an initial scheme of analysis, the pads were extracted with an acidic aqueous solution. This aqueous solution was then washed with CH2Cl2 and the organic phase discarded. The aqueous solution was then changed to basic and extracted with CH2Cl2, which was concentrated and analyzed via GC/MS. The dibenzacridine could not be detected utilizing this scheme, even when the pads had been spiked with a few thousand nanograms of dibenzacridine. After using several other organic solvents (cyclohexane, CHCl3, and benzene to eliminate the possibility that the extraction efficiency of CH2Cl2 was poor, it was determined that dibenzacridine was being discarded with the first CH2Cl2 wash. A successful separation scheme was developed by extracting the smoked pad with an aqueous acidic solution, followed by extraction of the aqueous phase with CH2Cl2without pH change. The CH2Cl2 extract was concentrated under nitrogen and 1 µL injected for GC/MS analysis. Quantification was achieved by spiking the pads with dibenz[a,j]acridine-d13 as an internal standard at a level equal to 1.7-2.5 ng/cig. The limit of detection for this technique was approximately 0.5 ng/cig. The chromatographic separation was performed with a 30 m BPX-5 column (0.25 mm i.d., 0.25 µm film thickness. Mass spectral data were acquired in selected ion monitoring (SIM mode with m/z = 279 for the two dibenzacridine isomers and m/z = 292 for the deuterated internal standard. Three commercial cigarettes were

Application of non-aqueous solvents to batteries. I Physicochemical properties of propionitrile/water two-phase solvent relevant to zinc-bromine batteries

Science.gov (United States)

Singh, P.; White, K.; Parker, A. J.

1983-11-01

The properties of bromine/propionitrile solution are investigated with a view to its use as an electrolyte in zinc-bromine batteries which use circulating electrolyte. The solution, which forms a two-phase system with water, has higher conductivity than the oils formed by complexation of bromine with organic salts such as N,N-methoxymethyl methylpiperidinium bromide and N,N-ethyl methylmorpholinium bromide. The activity of bromine in the aqueous phase of the bromine-propionitrile/water, two-phase system is very low; thus, coulombic efficiencies greater than 85 percent are achieved. Zinc-bromine batteries containing this solvent system show good charge/discharge characteristics.

Experimental measurements of U60 nanocluster stability in aqueous solution

Science.gov (United States)

Flynn, Shannon L.; Szymanowski, Jennifer E. S.; Gao, Yunyi; Liu, Tianbo; Burns, Peter C.; Fein, Jeremy B.

2015-05-01

In this study, the aqueous behavior of isolated U60 nanoclusters (K16Li25[UO2(O2)OH]60)-19 was studied under several pH conditions and nanocluster concentrations to determine if the nanoclusters exhibit solid phase buffering behavior or if they exhibit behavior more like aqueous complexes. U60 is a cage cluster consisting of 60 (UO2)(O2)2(OH)2 uranyl polyhedral which share OH and O2 groups with their neighboring uranyl polyhedral, resulting in negatively charged cage clusters whose charge is at least partially offset by K+ and Li+ in the aqueous phase. Batch experiments to monitor nanocluster stability were conducted for 16 days at pH 7.5, 8.0 and 8.5 at nanocluster suspension concentrations of 1.4, 2.8 and 6.0 g/L. The aqueous concentrations of U, Li, and K, determined after 10 kDa molecular weight filtration, achieved steady-state with the nanoclusters within 24 h. The steady-state aqueous U, Li, and K concentrations were independent of solution pH, however they increased with increasing nanocluster concentration, indicating that the nanoclusters do not buffer the aqueous activities as a bulk solid phase would, but exhibit behavior that is more characteristic of dissolved aqueous complexes. The ion activity product (I.A.P.) value was calculated using two approaches: (1) treating the nanoclusters as a solid phase with an activity of one, and (2) treating the nanoclusters as aqueous complexes with a non-unit activity equal to their concentration in solution. The I.A.P. values that were calculated with non-unit activity for the nanoclusters exhibited significantly less variation as a function of nanocluster concentration compared to the I.A.P. values calculated with a nanocluster activity of one. The results yield a calculated log dissociation constant for the U60 nanoclusters of 9.2 + 0.2/-0.3 (1σ). Our findings provide a better understanding of the thermodynamic stability and behavior of U60 nanoclusters in aqueous systems, and can be used to estimate the

Adsorptive removal of phenol from aqueous phase by using a porous acrylic ester polymer

International Nuclear Information System (INIS)

Pan Bingjun; Pan Bingcai; Zhang Weiming; Zhang Qingrui; Zhang Quanxing; Zheng Shourong

2008-01-01

The removal of phenol from aqueous solution was examined by using a porous acrylic ester polymer (Amberlite XAD-7) as an adsorbent. Favorable phenol adsorption was observed at acidic solution pH and further increase of solution pH results in a marked decrease of adsorption capacity, and the coexisting inorganic salt NaCl exerts positive effect on the adsorption process. Adsorption isotherms of phenol were linearly correlated and found to be well represented by either the Langmuir or Freundlich isotherm model. Thermodynamic parameters such as changes in the enthalpy (ΔH), entropy (ΔS) and free energy (ΔG) indicate that phenol adsorption onto XAD-7 is an exothermic and spontaneous process in nature, and lower ambient temperature results in more favorable adsorption. Kinetic experiments at different initial solute concentrations were investigated and the pseudo-second-order kinetic model was successfully represented the kinetic data. Additionally, the column adsorption result showed that a complete removal of phenol from aqueous phase can be achieved by XAD-7 beads and the exhausted adsorbent was amenable to an entire regeneration by using ethanol as the regenerant. More interestingly, relatively more volume of hot water in place of ethanol can also achieve a similar result for repeated use of the adsorbent

A Designer Fluid for Aluminum Phase Change Devices, Vol. 1 of 3: General Inorganic Aqueous Solution (IAS) Chemistry

Science.gov (United States)

2016-11-17

out in wicked phase change heat transfer devices. Wen [18] used nanoparticle suspensions to successfully increase the boiling heat transfer...Aqueous Solution of an Anionic Surfactant,” Journal of Heat Transfer 122, No. 4: 708. [18] Wen , D. and Ding, Y., 2005, “Experimental Investigation...Li, Y., 1974, “Diffusion of Ions in Sea Water and in Deep -Sea Sediments,” Geochimica et Cosmochimica Acta, Vol. 88, pp. 703-714. [36] Negishi, K

Is there an aerosol signature of aqueous processing?

Science.gov (United States)

Ervens, B.; Sorooshian, A.

2017-12-01

The formation of aerosol mass in cloud water has been recognized as a substantial source of atmospheric aerosol mass. While sulfate formation can be relatively well constrained, the formation of secondary organic aerosol mass in the aqueous phase (aqSOA) is much more complex due to the multitude of precursors and variety in chemical processes. Aqueous phase processing adds aerosol mass to the droplet mode, which is formed due to mass addition to activated particles in clouds. In addition, it has been shown that aqSOA mass has specific characteristics in terms of oxidation state and hygroscopicity that might help to distinguish it from other SOA sources. Many models do not include detailed chemical mechanisms of sulfate and aqSOA formation and also lack details on the mass distribution of newly formed mass. Mass addition inside and outside clouds modifies different parts of an aerosol population and consequently affects predictions of properties and lifetime of particles. Using a combination of field data analysis and model studies for a variety of air masses, we will show which chemical and physical aerosol properties can be used, in order to identify an `aqueous phase signature' in processed aerosol populations. We will discuss differences in this signature in clean (e.g., background), moderately polluted (e.g., urban) and highly polluted (e.g., biomass burning) air masses and suggest air-mass-specific chemical and/or physical properties that will help to quantify the aqueous-phase derived aerosol mass.

Self-assembly in monoelaidin aqueous dispersions: direct vesicles to cubosomes transition.

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Anan Yaghmur

Full Text Available In the present study, synchrotron small-angle X-ray scattering (SAXS and Cryo-TEM were used to characterize the temperature-induced structural transitions of monoelaidin (ME aqueous dispersion in the presence of the polymeric stabilizer F127. We prove that the direct transition from vesicles to cubosomes by heating this dispersion is possible. The obtained results were compared with the fully hydrated bulk ME phase.Our results indicate the formation of ME dispersion, which is less stable than that based on the congener monoolein (MO. In addition, the temperature-dependence behavior significantly differs from the fully hydrated bulk phase. SAXS findings indicate a direct L(alpha-V(2 internal transition in the dispersion. While the transition temperature is conserved in the dispersion, the formed cubosomes with internal Im3m symmetry clearly contain more water and this ordered interior is retained over a wider temperature range as compared to its fully hydrated bulk system. At 25 degrees C, Cryo-TEM observations reveal the formation of most likely closely packed onion-like vesicles. Above the lamellar to non-lamellar phase transition at 65 degrees C, flattened cubosomes with an internal nanostructure are observed. However, they have only arbitrary shapes and thus, their morphology is significantly different from that of the well-shaped analogous MO cubosome and hexosome particles.Our study reveals a direct liposomes-cubosomes transition in ME dispersion. The obtained results suggest that the polymeric stabilizer F127 especially plays a significant role in the membrane fusion processes. F127 incorporates in considerable amount into the internal nanostructure and leads to the formation of a highly swollen Im3m phase.

Materials Applications for Non-Lethal: Aqueous Foams

Energy Technology Data Exchange (ETDEWEB)

GOOLSBY,TOMMY D.; SCOTT,STEVEN H.

1999-09-15

High expansion aqueous foam is an aggregation of bubbles that has the appearance of soap suds and is used to isolate individuals both visually and acoustically. It was developed in the 1920's in England to fight coal mine fires and has been widely used since for fire fighting and dust suppression. It was developed at Sandia National Laboratories (SNL) in the 1970's for nuclear safeguards and security applications. In the mid-1990s, the National Institute of Justice (NIJ), the research arm of the Department of Justice, began a project with SNL to determine the applicability of high expansion aqueous foam for correctional applications. NIJ funded the project as part of its search for new and better less-than-lethal weapons for responding to violent and dangerous individuals, where other means of force could lead to serious injuries. The phase one objectives of the project were to select a low-to-no toxicity foam concentrate (foaming agent) with physical characteristics suited for use in a single cell or large prison disturbances, and to determine if the selected foam concentrate could serve as a carrier for Oleoresin Capsicum (OC) irritant. The phase two objectives were to conduct an extensive toxicology review of the selected foam concentrate and OC irritant, and to conduct respiration simulation experiments in the selected high expansion aqueous foam. The phase three objectives were to build a prototype individual cell aqueous foam system and to study the feasibility of aqueous foams for large prison facility disturbances. The phase four and five objectives were to use the prototype system to do large scale foam physical characteristics testing of the selected foam concentrate, and to have the prototype single cell system further evaluated by correctional representatives. Prison rather than street scenarios were evaluated as the first and most likely place for using the aqueous foam since prisons have recurrent incidents where officers and inmates might

Materials Applications for Non-Lethal: Aqueous Foams

International Nuclear Information System (INIS)

GOOLSBY, TOMMY D.; SCOTT, STEVEN H.

1999-01-01

High expansion aqueous foam is an aggregation of bubbles that has the appearance of soap suds and is used to isolate individuals both visually and acoustically. It was developed in the 1920's in England to fight coal mine fires and has been widely used since for fire fighting and dust suppression. It was developed at Sandia National Laboratories (SNL) in the 1970's for nuclear safeguards and security applications. In the mid-1990s, the National Institute of Justice (NIJ), the research arm of the Department of Justice, began a project with SNL to determine the applicability of high expansion aqueous foam for correctional applications. NIJ funded the project as part of its search for new and better less-than-lethal weapons for responding to violent and dangerous individuals, where other means of force could lead to serious injuries. The phase one objectives of the project were to select a low-to-no toxicity foam concentrate (foaming agent) with physical characteristics suited for use in a single cell or large prison disturbances, and to determine if the selected foam concentrate could serve as a carrier for Oleoresin Capsicum (OC) irritant. The phase two objectives were to conduct an extensive toxicology review of the selected foam concentrate and OC irritant, and to conduct respiration simulation experiments in the selected high expansion aqueous foam. The phase three objectives were to build a prototype individual cell aqueous foam system and to study the feasibility of aqueous foams for large prison facility disturbances. The phase four and five objectives were to use the prototype system to do large scale foam physical characteristics testing of the selected foam concentrate, and to have the prototype single cell system further evaluated by correctional representatives. Prison rather than street scenarios were evaluated as the first and most likely place for using the aqueous foam since prisons have recurrent incidents where officers and inmates might be

Ice crystallization in ultrafine water-salt aerosols: nucleation, ice-solution equilibrium, and internal structure.

Science.gov (United States)

Hudait, Arpa; Molinero, Valeria

2014-06-04

Atmospheric aerosols have a strong influence on Earth's climate. Elucidating the physical state and internal structure of atmospheric aqueous aerosols is essential to predict their gas and water uptake, and the locus and rate of atmospherically important heterogeneous reactions. Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers in the troposphere and tropopause. Nanoscopic aerosols arising from bubble bursting of natural and artificial seawater have been identified in laboratory and field experiments. The internal structure and phase state of these aerosols, however, cannot yet be determined in experiments. Here we use molecular simulations to investigate the phase behavior and internal structure of liquid, vitrified, and crystallized water-salt ultrafine aerosols with radii from 2.5 to 9.5 nm and with up to 10% moles of ions. We find that both ice crystallization and vitrification of the nanodroplets lead to demixing of pure water from the solutions. Vitrification of aqueous nanodroplets yields nanodomains of pure low-density amorphous ice in coexistence with vitrified solute rich aqueous glass. The melting temperature of ice in the aerosols decreases monotonically with an increase of solute fraction and decrease of radius. The simulations reveal that nucleation of ice occurs homogeneously at the subsurface of the water-salt nanoparticles. Subsequent ice growth yields phase-segregated, internally mixed, aerosols with two phases in equilibrium: a concentrated water-salt amorphous mixture and a spherical cap-like ice nanophase. The surface of the crystallized aerosols is heterogeneous, with ice and solution exposed to the vapor. Free energy calculations indicate that as the concentration of salt in the particles, the advance of the crystallization, or the size of the particles increase, the stability of the spherical cap structure increases with respect to the alternative structure in which a core of ice is fully surrounded by

The impact of ionic liquid fluorinated moieties on their thermophysical properties and aqueous phase behaviour.

Science.gov (United States)

Neves, Catarina M S S; Kurnia, Kiki A; Shimizu, Karina; Marrucho, Isabel M; Rebelo, Luís Paulo N; Coutinho, João A P; Freire, Mara G; Lopes, José N Canongia

2014-10-21

In this work, we demonstrate that the presence of fluorinated alkyl chains in Ionic Liquids (ILs) is highly relevant in terms of their thermophysical properties and aqueous phase behaviour. We have measured and compared the density and viscosity of pure 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate, [C2C1im][FAP], with that of pure 1-ethyl-3-methylimidazolium hexafluorophosphate, [C2C1im][PF6], at atmospheric pressure and in the (288.15 to 363.15) K temperature range. The results show that the density of [C2C1im][PF6] is lower than that of [C2C1im][FAP], while the viscosity data reveal the opposite trend. The fluid phase behaviour of aqueous solutions of the two ILs was also evaluated under the same conditions and it was found that the mutual solubilities of [C2C1im][FAP] and water are substantially lower than those verified with [C2C1im][PF6]. The experimental data were lastly interpreted at a molecular level using Molecular Dynamics (MD) simulation results revealing that the interactions between the IL ions and the water molecules are mainly achieved via the six fluorine atoms of [PF6](-) and the three analogues in [FAP](-). The loss of three interaction centres when replacing [PF6](-) by [FAP](-), coupled with the bulkiness and relative inertness of the three perfluoroethyl groups, reduces its mutual solubility with water and also contributes to a lower viscosity displayed by the pure [FAP]-based IL as compared to that of the [PF6]-based compound.

Aqueous Two-Phase Systems: A New Approach for the Determination of Brilliant Blue FCF in Water and Food Samples

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Sabah Shiri

2013-01-01

Full Text Available A novel, simple, and more sensitive spectrophotometric procedure has been developed for the determination of brilliant blue FCF in water and food samples by an aqueous two-phase system (ATPS. In this method, adequate amount of polyethylene glycol/ sodium carbonate (PEG-4000/Na2CO3 was added to aqueous solution for formation of a homogeneous solution. To the mixture solution, suitable amount of Na2CO3 was added, the mixture solution was shaken until the salt was dissolved, and then it was separated into two clear phases easily and rapidly. The target analyte in the water sample was extracted into the polyethylene glycol phase. After extraction, measuring the absorbance at 634 nm was done. The effects of different parameters such as polyethylene glycol (type and concentration, pH, salt (type and amount, centrifuge time, and temperature on the ATPS of dye was investigated and optimum conditions were established. Linear calibration curves were obtained in the range of 0.25–750 ng/mL for brilliant blue FCF under optimum conditions. Detection limit based on three times the standard deviation of the blank (3Sb was 0.12 ng/mL. The relative standard deviation (RSD for 400 ng/mL was 3.14%. The method was successfully applied to the determination of brilliant blue FCF in spiked samples with satisfactory results. The relative recovery was between 96.0 and 102.2%.

WxC-β-SiC Nanocomposite Catalysts Used in Aqueous Phase Hydrogenation of Furfural.

Science.gov (United States)

Rogowski, Jacek; Andrzejczuk, Mariusz; Berlowska, Joanna; Binczarski, Michal; Kregiel, Dorota; Kubiak, Andrzej; Modelska, Magdalena; Szubiakiewicz, Elzbieta; Stanishevsky, Andrei; Tomaszewska, Jolanta; Witonska, Izabela Alina

2017-11-22

This study investigates the effects of the addition of tungsten on the structure, phase composition, textural properties and activities of β-SiC-based catalysts in the aqueous phase hydrogenation of furfural. Carbothermal reduction of SiO₂ in the presence of WO₃ at 1550 °C in argon resulted in the formation of W x C-β-SiC nanocomposite powders with significant variations in particle morphology and content of W x C-tipped β-SiC nano-whiskers, as revealed by TEM and SEM-EDS. The specific surface area (SSA) of the nanocomposite strongly depended on the amount of tungsten and had a notable impact on its catalytic properties for the production of furfuryl alcohol (FA) and tetrahydrofurfuryl alcohol (THFA). Nanocomposite W x C-β-SiC catalysts with 10 wt % W in the starting mixture had the highest SSA and the smallest W x C crystallites. Some 10 wt % W nanocomposite catalysts demonstrated up to 90% yield of THFA, in particular in the reduction of furfural derived from biomass, although the reproducible performance of such catalysts has yet to be achieved.

High temperature aqueous potassium and sodium phosphate solutions: two-liquid-phase boundaries and critical phenomena, 275-4000C; potential applications for steam generators

International Nuclear Information System (INIS)

Marshall, W.L.

1981-12-01

Two-liquid-phase boundaries at temperatures between 275 and 400 0 C were determined for potassium phosphate and sodium phosphate aqueous solutions for compositions from 0 to 60 wt % dissolved salt. The stoichiometric mole ratios, K/PO 4 or Na/PO 4 , were varied from 1.00 to 2.12 and from 1.00 to 2.16 for the potassium and sodium systems, respectively. Liquid-vapor critical temperatures were also determined for most of the dilute liquid phases that formed. The minimum temperatures (below which a single solution existed) of two-liquid-phase formation were 360 0 C for the potassium system and 279 0 C for the sodium system at mole ratios of 2.00 and 2.16, respectively. For the sodium system at mole ratios greater than 2.16, solids crystallized at lower temperatures as expected from earlier studies. In contrast, potassium solutions that were explored at mole ratios from 2.12 to 3.16 and at temperatures below 360 0 C did not produce solid phases nor liquid-liquid immiscibilities. Aside from the generally unusual observations of two immiscible liquids in an aqueous inorganic salt system, the results could possibly be applied to the use of phosphate additives in steam power generators. 16 refs

The international INTRAVAL project. Phase 2, Summary report

International Nuclear Information System (INIS)

Larsson, A.; Pers, K.; Skagius, K.; Dverstorp, B.

1997-01-01

The international project INTRAVAL addresses the validation of models of transport of radionuclides through groundwater in the geosphere. Such models are used in the assessment of the long-term safety of radioactive waste disposal systems. The second phase of INTRAVAL, which started in 1990, was concluded at the end of 1993. The objective of Phase 2 was to increase the understanding how various geophysical, geohydrological and geochemical phenomena of importance for radionuclide transport from a repository to the biosphere could be described by mathematical models and to study the model validation process. Summarized results from Phase 2 of the INTRAVAL study are presented in this report. (K.A.)

Flocculation kinetics of kaolinite : role of aqueous phase species

Energy Technology Data Exchange (ETDEWEB)

House, P.; Wang, C.; Dhadli, N. [Shell Canada Ltd., Calgary, AB (Canada)

2010-07-01

Flocculation kinetics were used to study the rate-based processes that lead to aggregate growth and breakage of kaolinite in oil sands tailings. The role of aqueous phase species on aggregate growth, breakage and flocculant de-activation was studied. Collision efficiency and deactivation parameters were presented. The study showed that collisions can be efficient when the adsorption of the polymer is thermodynamically favorable. Up to 94 percent of adsorption takes place at the kaolinite edge. Studies have shown that hydrogen bonding sites on the kaolinite disappear with increases in pH values. The impact of molecular level interactions on flocculation kinetics were assessed in order to determine collision efficiencies and aggregate breakage rates. A focused beam reflectance model was used to monitor flocculation kinetics in situ. The period over which reflectance was observed was coupled with the laser velocity to determine the chord length of the particle. The kinetics of flocculation were observed for a 10 minute period. The effects of pH, calcium additions, and EDTA chelating agent additions were investigated. The study showed that calcium additions accelerate the rate of flocculant growth dramatically, and provide a much higher collision efficiency. Flocculants formed in the presence of calcium were weaker. The presence of salts promoted polymer adsorption by non-specific Van der Waals forces. tabs., figs.

Identifying precursors and aqueous organic aerosol formation pathways during the SOAS campaign

Directory of Open Access Journals (Sweden)

N. Sareen

2016-11-01

Full Text Available Aqueous multiphase chemistry in the atmosphere can lead to rapid transformation of organic compounds, forming highly oxidized, low-volatility organic aerosol and, in some cases, light-absorbing (brown carbon. Because liquid water is globally abundant, this chemistry could substantially impact climate, air quality, and health. Gas-phase precursors released from biogenic and anthropogenic sources are oxidized and fragmented, forming water-soluble gases that can undergo reactions in the aqueous phase (in clouds, fogs, and wet aerosols, leading to the formation of secondary organic aerosol (SOAAQ. Recent studies have highlighted the role of certain precursors like glyoxal, methylglyoxal, glycolaldehyde, acetic acid, acetone, and epoxides in the formation of SOAAQ. The goal of this work is to identify additional precursors and products that may be atmospherically important. In this study, ambient mixtures of water-soluble gases were scrubbed from the atmosphere into water at Brent, Alabama, during the 2013 Southern Oxidant and Aerosol Study (SOAS. Hydroxyl (OH⚫ radical oxidation experiments were conducted with the aqueous mixtures collected from SOAS to better understand the formation of SOA through gas-phase followed by aqueous-phase chemistry. Total aqueous-phase organic carbon concentrations for these mixtures ranged from 92 to 179 µM-C, relevant for cloud and fog waters. Aqueous OH-reactive compounds were primarily observed as odd ions in the positive ion mode by electrospray ionization mass spectrometry (ESI-MS. Ultra high-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS spectra and tandem MS (MS–MS fragmentation of these ions were consistent with the presence of carbonyls and tetrols. Products were observed in the negative ion mode and included pyruvate and oxalate, which were confirmed by ion chromatography. Pyruvate and oxalate have been found in the particle phase in many locations (as salts and

Atom exchange between aqueous Fe(II) and structural Fe in clay minerals.

Science.gov (United States)

Neumann, Anke; Wu, Lingling; Li, Weiqiang; Beard, Brian L; Johnson, Clark M; Rosso, Kevin M; Frierdich, Andrew J; Scherer, Michelle M

2015-03-03

Due to their stability toward reductive dissolution, Fe-bearing clay minerals are viewed as a renewable source of Fe redox activity in diverse environments. Recent findings of interfacial electron transfer between aqueous Fe(II) and structural Fe in clay minerals and electron conduction in octahedral sheets of nontronite, however, raise the question whether Fe interaction with clay minerals is more dynamic than previously thought. Here, we use an enriched isotope tracer approach to simultaneously trace Fe atom movement from the aqueous phase to the solid ((57)Fe) and from the solid into the aqueous phase ((56)Fe). Over 6 months, we observed a significant decrease in aqueous (57)Fe isotope fraction, with a fast initial decrease which slowed after 3 days and stabilized after about 50 days. For the aqueous (56)Fe isotope fraction, we observed a similar but opposite trend, indicating that Fe atom movement had occurred in both directions: from the aqueous phase into the solid and from the solid into aqueous phase. We calculated that 5-20% of structural Fe in clay minerals NAu-1, NAu-2, and SWa-1 exchanged with aqueous Fe(II), which significantly exceeds the Fe atom layer exposed directly to solution. Calculations based on electron-hopping rates in nontronite suggest that the bulk conduction mechanism previously demonstrated for hematite1 and suggested as an explanation for the significant Fe atom exchange observed in goethite2 may be a plausible mechanism for Fe atom exchange in Fe-bearing clay minerals. Our finding of 5-20% Fe atom exchange in clay minerals indicates that we need to rethink how Fe mobility affects the macroscopic properties of Fe-bearing phyllosilicates and its role in Fe biogeochemical cycling, as well as its use in a variety of engineered applications, such as landfill liners and nuclear repositories.

Initiating a New Research Phase in the Field of International Entrepreneurship

DEFF Research Database (Denmark)

Coviello, Nicole; Tanev, Stoyan

2017-01-01

In a recent publication, Nicole Coviello (2015) emphasized the need to re-think existing research on international entrepreneurship and, more specifically, research on born-global firms. She pointed out that the main value of a critical review lies in initiating a new research phase focusing on t...... be of relevance for new technology firms aiming at an international or global engagement from their very inception.......In a recent publication, Nicole Coviello (2015) emphasized the need to re-think existing research on international entrepreneurship and, more specifically, research on born-global firms. She pointed out that the main value of a critical review lies in initiating a new research phase focusing...

submitter Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

CERN Document Server

Hoyle, C R; Järvinen, E; Saathoff, H; Dias, A; El Haddad, I; Gysel, M; Coburn, S C; Tröstl, J; Bernhammer, A -K; Bianchi, F; Breitenlechner, M; Corbin, J C; Craven, J; Donahue, N M; Duplissy, J; Ehrhart, S; Frege, C; Gordon, H; Höppel, N; Heinritzi, M; Kristensen, T B; Molteni, U; Nichman, L; Pinterich, T; Prévôt, A S H; Simon, M; Slowik, J G; Steiner, G; Tomé, A; Vogel, A L; Volkamer, R; Wagner, A C; Wagner, R; Wexler, A S; Williamson, C; Winkler, P M; Yan, C; Amorim, A; Dommen, J; Curtius, J; Gallagher, M W; Flagan, R C; Hansel, A; Kirkby, J; Kulmala, M; Möhler, O; Stratmann, F; Worsnop, D R; Baltensperger, U

2016-01-01

The growth of aerosol due to the aqueous phase oxidation of sulfur dioxide by ozone was measured in laboratory-generated clouds created in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). Experiments were performed at 10 and −10 °C, on acidic (sulfuric acid) and on partially to fully neutralised (ammonium sulfate) seed aerosol. Clouds were generated by performing an adiabatic expansion – pressurising the chamber to 220 hPa above atmospheric pressure, and then rapidly releasing the excess pressure, resulting in a cooling, condensation of water on the aerosol and a cloud lifetime of approximately 6 min. A model was developed to compare the observed aerosol growth with that predicted using oxidation rate constants previously measured in bulk solutions. The model captured the measured aerosol growth very well for experiments performed at 10 and −10 °C, indicating that, in contrast to some previous studies, the oxidation rates of SO2 in ...

Extraction of actinide and lanthanide complexonates in two-phase aqueous system potassium carbonate-polyethylene glycol-water

International Nuclear Information System (INIS)

Molochnikova, N.P.; Shkinev, V.M.; Spivakov, B.Ya.; Zolotov, Yu.A.; Myasoedov, B.F.

1988-01-01

Extraction system on the basis of polyethylene glycol for the concentration, isolation and separation of actinides is suggested. Extraction of actinides and lanthanides in two-phase aqueous system: potassium carbonate - polyethylene glycol - water in the presence of different complexones is investigated. Trivalent actinides are extracted quantitatively by polyethylene glycol from potassium carbonate solutions in the system with xylenol orange and alizarin-complexone. Under the conditions uranium (6) and plutonium (4) are extracted into the phase, enriched by polyethylene glycol, quite insignificantly, which permits to separate them from trivalent actinides with the separation factor of 10 2 - 10 3 . For actinide and lanthanide separation two complexones were introduced into the system, one of them being extractant, the other one - camouflaging reactant. The best results are obtained for the mixture of xylenol orange and hydroxyethylenediphosphonic acid. Separation coefficients for americium and europium constitute 4.5 - 5.6

A plant-wide aqueous phase chemistry module describing pH variations and ion speciation/pairing in wastewater treatment process models.

Science.gov (United States)

Flores-Alsina, Xavier; Kazadi Mbamba, Christian; Solon, Kimberly; Vrecko, Darko; Tait, Stephan; Batstone, Damien J; Jeppsson, Ulf; Gernaey, Krist V

2015-11-15

There is a growing interest within the Wastewater Treatment Plant (WWTP) modelling community to correctly describe physico-chemical processes after many years of mainly focusing on biokinetics. Indeed, future modelling needs, such as a plant-wide phosphorus (P) description, require a major, but unavoidable, additional degree of complexity when representing cationic/anionic behaviour in Activated Sludge (AS)/Anaerobic Digestion (AD) systems. In this paper, a plant-wide aqueous phase chemistry module describing pH variations plus ion speciation/pairing is presented and interfaced with industry standard models. The module accounts for extensive consideration of non-ideality, including ion activities instead of molar concentrations and complex ion pairing. The general equilibria are formulated as a set of Differential Algebraic Equations (DAEs) instead of Ordinary Differential Equations (ODEs) in order to reduce the overall stiffness of the system, thereby enhancing simulation speed. Additionally, a multi-dimensional version of the Newton-Raphson algorithm is applied to handle the existing multiple algebraic inter-dependencies. The latter is reinforced with the Simulated Annealing method to increase the robustness of the solver making the system not so dependent of the initial conditions. Simulation results show pH predictions when describing Biological Nutrient Removal (BNR) by the activated sludge models (ASM) 1, 2d and 3 comparing the performance of a nitrogen removal (WWTP1) and a combined nitrogen and phosphorus removal (WWTP2) treatment plant configuration under different anaerobic/anoxic/aerobic conditions. The same framework is implemented in the Benchmark Simulation Model No. 2 (BSM2) version of the Anaerobic Digestion Model No. 1 (ADM1) (WWTP3) as well, predicting pH values at different cationic/anionic loads. In this way, the general applicability/flexibility of the proposed approach is demonstrated, by implementing the aqueous phase chemistry module in some

17th International Conference on Petroleum Phase Behavior and Fouling

DEFF Research Database (Denmark)

von Solms, Nicolas; Yan, Wei; Andersen, Simon

2017-01-01

This special section of Energy & Fuels contains contributedpapers from the 17th International Conference on PetroleumPhase Behavior and Fouling (Petrophase 2016). Petrophase 2016 was organized by the Technical University of Denmark and Schlumberger and took place in Elsinore (Helsingør) Denmark...... from June 19th to 23rd at the Beach Hotel Marienlyst. Petrophase is an international conference aimed at researchers in industry and academia dedicated to the study of the properties and chemistry of petroleum fluids and their effect on producing, processing, and refining in the upstream, midstream......, and downstream industries. The conference started in 1999 as “The International Conference on Petroleum Phase Behavior & Fouling” and has since evolved into an annual event taking place in countries all around the world. Petrophase has been fortunate to have enjoyed financial and organizational support from many...

Calculation of liquid-liquid equilibrium of aqueous two-phase systems using a chemical-theory-based excess Gibbs energy model

Directory of Open Access Journals (Sweden)

Pessôa Filho P. A.

2004-01-01

Full Text Available Mixtures containing compounds that undergo hydrogen bonding show large deviations from ideal behavior. These deviations can be accounted for through chemical theory, according to which the formation of a hydrogen bond can be treated as a chemical reaction. This chemical equilibrium needs to be taken into account when applying stability criteria and carrying out phase equilibrium calculations. In this work, we illustrate the application of the stability criteria to establish the conditions under which a liquid-phase split may occur and the subsequent calculation of liquid-liquid equilibrium using a chemical-theory-modified Flory-Huggins equation to describe the non ideality of aqueous two-phase systems composed of poly(ethylene glycol and dextran. The model was found to be able to correlate ternary liquid-liquid diagrams reasonably well by simple adjustment of the polymer-polymer binary interaction parameter.

Separation of Cd and Ni from Ni-Cd batteries by an environmentally safe methodology employing aqueous two-phase systems

Energy Technology Data Exchange (ETDEWEB)

Lacerda, Vania Goncalves; Mageste, Aparecida Barbosa; Santos, Igor Jose Boggione; da Silva, Luis Henrique Mendes; da Silva, Maria do Carmo Hespanhol [Grupo de Quimica Verde Coloidal e Macromolecular, Departamento de Quimica, Centro de Ciencias e Tecnologicas, Universidade Federal de Vicosa, Av. P.H. Rolfs s/n, Campus da UFV, Vicosa, 36570-000 (Brazil)

2009-09-05

The separation of Cd and Ni from Ni-Cd batteries using an aqueous two-phase system (ATPS) composed of copolymer L35, Li{sub 2}SO{sub 4} and water is investigated. The extraction behavior of these metals from the bottom phase (BP) to the upper phase (UP) of the ATPS is affected by the amount of added extractant (potassium iodide), tie-line length (TLL), mass ratio between the phases of the ATPS, leaching and dilution factor of the battery samples. Maximum extraction of Cd (99.2 {+-} 3.1)% and Ni (10.6 {+-} 0.4)% is obtained when the batteries are leached with HCl, under the following conditions: 62.53% (w/w) TLL, concentration of KI equal to 50.00 mmol kg{sup -1}, mass ratio of the phases equal to 0.5 and a dilution factor of battery samples of 35. This novel methodology is efficient to separate the metals in question, with the advantage of being environmentally safe, since water is the main constituent of the ATPS, which is prepared with recyclable and biodegradable compounds. (author)

Enantioseparation of Racemic Flurbiprofen by Aqueous Two-Phase Extraction With Binary Chiral Selectors of L-dioctyl Tartrate and L-tryptophan.

Science.gov (United States)

Chen, Zhi; Zhang, Wei; Wang, Liping; Fan, Huajun; Wan, Qiang; Wu, Xuehao; Tang, Xunyou; Tang, James Z

2015-09-01

A novel method for chiral separation of flurbiprofen enantiomers was developed using aqueous two-phase extraction (ATPE) coupled with biphasic recognition chiral extraction (BRCE). An aqueous two-phase system (ATPS) was used as an extracting solvent which was composed of ethanol (35.0% w/w) and ammonium sulfate (18.0% w/w). The chiral selectors in ATPS for BRCE consideration were L-dioctyl tartrate and L-tryptophan, which were screened from amino acids, β-cyclodextrin derivatives, and L-tartrate esters. Factors such as the amounts of L-dioctyl tartrate and L-tryptophan, pH, flurbiprofen concentration, and the operation temperature were investigated in terms of chiral separation of flurbiprofen enantiomers. The optimum conditions were as follows: L-dioctyl tartrate, 80 mg; L-tryptophan, 40 mg; pH, 4.0; flurbiprofen concentration, 0.10 mmol/L; and temperature, 25 °C. The maximum separation factor α for flurbiprofen enantiomers could reach 2.34. The mechanism of chiral separation of flurbiprofen enantiomers is discussed and studied. The results showed that synergistic extraction has been established by L-dioctyl tartrate and L-tryptophan, which enantioselectively recognized R- and S-enantiomers in top and bottom phases, respectively. Compared to conventional liquid-liquid extraction, ATPE coupled with BRCE possessed higher separation efficiency and enantioselectivity without the use of any other organic solvents. The proposed method is a potential and powerful alternative to conventional extraction for separation of various enantiomers. © 2015 Wiley Periodicals, Inc.

Internal Reflection Sensor for the Cone Penetrometer. Innovative Technology Summary Report

International Nuclear Information System (INIS)

None

2001-01-01

The Internal Reflection Sensor, developed by EIC Laboratories, Inc. as a cone penetrometer based technology, provides real-time detection of subsurface non-aqueous phase liquids (NAPLs). The internal reflection element is positioned against the wall of the cone penetrometer probe such that its sensing face is in contact with the soil or groundwater as the cone is pushed into the subsurface. When NAPL is present and in contact with the sensing face, the internally reflected light is diminished. This results in a decrease in the signal output by the detector - a positive indicator of NAPL presence

WxC-β-SiC Nanocomposite Catalysts Used in Aqueous Phase Hydrogenation of Furfural

Directory of Open Access Journals (Sweden)

Jacek Rogowski

2017-11-01

Full Text Available This study investigates the effects of the addition of tungsten on the structure, phase composition, textural properties and activities of β-SiC-based catalysts in the aqueous phase hydrogenation of furfural. Carbothermal reduction of SiO2 in the presence of WO3 at 1550 °C in argon resulted in the formation of WxC-β-SiC nanocomposite powders with significant variations in particle morphology and content of WxC-tipped β-SiC nano-whiskers, as revealed by TEM and SEM-EDS. The specific surface area (SSA of the nanocomposite strongly depended on the amount of tungsten and had a notable impact on its catalytic properties for the production of furfuryl alcohol (FA and tetrahydrofurfuryl alcohol (THFA. Nanocomposite WxC-β-SiC catalysts with 10 wt % W in the starting mixture had the highest SSA and the smallest WxC crystallites. Some 10 wt % W nanocomposite catalysts demonstrated up to 90% yield of THFA, in particular in the reduction of furfural derived from biomass, although the reproducible performance of such catalysts has yet to be achieved.

Extraction of UO22+ by two highly sterically hindered (X1) (X2) PO(OH) extractants from an aqueous chloride phase

International Nuclear Information System (INIS)

Mason, G.W.; Lewey, S.M.; Gilles, D.M.; Peppard, D.F.

1978-01-01

The comparative extraction behaviour of tracer-level UO 2 2+ into benzene solutions of two highly sterically hindered extractants, di(2,6-di-iso-propylphenyl) phosphoric acid, HD(2,6-i-PPHI)P and di-tertiary-butyl phosphinic acid, H[Dt-BP], vs an aqueous 1.0 F (NaCl + HCl) phase was studied. The extraction of UO 2 2+ in both systems is directly second-power dependent upon extractant concentration and inversely second-power dependent upon hydrogen ion concentration, the stoichiometry of extraction being UOsub(2A) 2+ + 2(HY)sub(2O) = UO 2 (HY 2 )sub(2O) + 2Hsub(A) + . The expression for the distribution ratio, K is K = Ksub(s)F 2 /[H + ] 2 the general expression for the extraction of any metallic species being K - Ksub(s)Fsup(a)/[H + ]sup(b) where Ksub(s) is a constant characteristic of the system, F the concentration in formality units of extractant in the organic phase, [H + ] the concentration of hydrogen ion in the aqueous phase, and a and b the respective extractant and hydrogen-ion dependencies. Both extractants have a high degree of steric hindrance. The HD(2,6-i-PPHI)P is the more highly acidic, the pKsub(A) value, in 75% ethanol, being 3.2. The pKsub(A), previously reported, for H[Dt-BP] is 6.26. The Ksub(s) for UO 2 2+ in the system HY in benzene diluent vs an aqueous 1.0 F (NaCl + HCl) phase is 2 x 10 4 for H[Dt-BP] and 3 x 10 -1 for HD(2,6-i-PPHI)P; the ratio of the Ksub(s) values nearly 7 x 10 3 , favours the less acidic extractant. For comparative purposes, the Ksub(s) values for UO 2 2+ and for Am 3+ and Eu 3+ in other (X 1 )(X 2 )PO(OH), in benzene diluent, vs 1.0 F (NaCl + HCl) systems are presented. The variations are discussed in terms of the pKsub(A) of the extractant and the steric hindrance within the extractant. (author)

A Novel Aqueous Micellar Two-Phase System Composed of Surfactant and Sorbitol for Purification of Pectinase Enzyme from Psidium guajava and Recycling Phase Components

Science.gov (United States)

Murshid, Fara Syazana; Manap, Mohd Yazid; Hussin, Muhaini

2015-01-01

A novel aqueous two-phase system composed of a surfactant and sorbitol was employed for the first time to purify pectinase from Psidium guajava. The influences of different parameters, including the type and concentration of the surfactant and the concentration and composition of the surfactant/sorbitol ratio, on the partitioning behavior and recovery of pectinase were investigated. Moreover, the effects of system pH and the crude load on purification fold and the yield of purified pectinase were studied. The experimental results indicated that the pectinase was partitioned into surfactant-rich top phase, and the impurities were partitioned into the sorbitol-rich bottom phase with the novel method involving an ATPS composed of 26% (w/w) Triton X-100 and 23% (w/w) sorbitol at 54.2% of the TLL crude load of 20% (w/w) at pH 6.0. The enzyme was successfully recovered by this method with a high purification factor of 15.2 and a yield of 98.3%, whereas the phase components were also recovered and recycled at rates above 96%. This study demonstrated that this novel ATPS method can be used as an efficient and economical alternative to the traditional ATPS for the purification and recovery of the valuable enzyme. PMID:25756051

A novel aqueous micellar two-phase system composed of surfactant and sorbitol for purification of pectinase enzyme from Psidium guajava and recycling phase components.

Science.gov (United States)

Amid, Mehrnoush; Murshid, Fara Syazana; Manap, Mohd Yazid; Hussin, Muhaini

2015-01-01

A novel aqueous two-phase system composed of a surfactant and sorbitol was employed for the first time to purify pectinase from Psidium guajava. The influences of different parameters, including the type and concentration of the surfactant and the concentration and composition of the surfactant/sorbitol ratio, on the partitioning behavior and recovery of pectinase were investigated. Moreover, the effects of system pH and the crude load on purification fold and the yield of purified pectinase were studied. The experimental results indicated that the pectinase was partitioned into surfactant-rich top phase, and the impurities were partitioned into the sorbitol-rich bottom phase with the novel method involving an ATPS composed of 26% (w/w) Triton X-100 and 23% (w/w) sorbitol at 54.2% of the TLL crude load of 20% (w/w) at pH 6.0. The enzyme was successfully recovered by this method with a high purification factor of 15.2 and a yield of 98.3%, whereas the phase components were also recovered and recycled at rates above 96%. This study demonstrated that this novel ATPS method can be used as an efficient and economical alternative to the traditional ATPS for the purification and recovery of the valuable enzyme.

Characterization of nanocomposites produced from aqueous mini emulsion containing silver nanoparticles

International Nuclear Information System (INIS)

Reis, Milvia O.; Orefice, Rodrigo L.

2011-01-01

nanocomposites based on butyl acrylate and styrene monomers were synthesized through the process of free radical polymerization in miniemulsion. An aqueous solution of silver nanoparticles was synthesized and incorporated as the continuous phase (aqueous) to the dispersed phase (oil). To this mixture was added the hydrophobic agent hexadecane and subject to thermodynamic stabilization bu ultrasonification. The nanocomposite films were characterized by FTIR and XRF and their thermal properties evaluated by DSC and TGA. (author)

Simultaneous determination of seven alkaloids from Rhizoma Corydalis Decumbentis in rabbit aqueous humor by LC-MS/MS: Application to ocular pharmacokinetic studies.

Science.gov (United States)

Mao, Zhengsheng; Wang, Xin; Liu, Yangdan; Huang, Yuting; Liu, Youping; Di, Xin

2017-07-01

This study aims to establish a fast and sensitive LC-MS/MS method for simultaneous determination of seven alkaloids from Rhizoma Corydalis Decumbentis in rabbit aqueous humor. Aqueous humor samples were processed by protein precipitation and then separated on a Thermo Syncronis C 18 column (50mm×2.1mm, 5μm) with a mobile phase using acetonitrile-0.05% formic acid (28:72, v/v). Detection of the analytes and the internal standard (coptisine) were performed in positive electrospray ionization with selected reaction monitoring. The method showed good linearity (r>0.9931) for all the seven alkaloids. This fully validated method was applied to the studies of aqueous humor pharmacokinetics of seven alkaloids from Rhizoma Corydalis Decumbentis and the effects of borneol on corneal penetration of these alkaloids into aqueous humor. This is the first work that presents a reliable LC-MS/MS method for simultaneous determination of seven alkaloids in rabbit aqueous humor and its application of ocular pharmacokinetics of seven alkaloids from Rhizoma Corydalis Decumbentis. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Energy Technology Data Exchange (ETDEWEB)

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

Design and development of a digital phase ratio meter

Energy Technology Data Exchange (ETDEWEB)

Majee, B C [Reactor Control Division, Bhabha Atomic Research Centre, Mumbai (India); Roy, S B; Meghal, A M [Uranium Extraction Division, Bhabha Atomic Research Centre, Mumbai (India)

1994-06-01

Uranium purification at Uranium Metal Plant is being carried out using solvent extraction process. The feed is aqueous uranyl nitrate solution with 2-4% insoluble silica particles. The solvent is tri-butyl phosphate diluted with commercial grade kerosene. Extraction is conducted in a slurry extractor equipment using compressed air as mixing and solution-interstage transferring medium. To ensure the organic continuous mode in the mixer and to avoid stable emulsion formation, organic to aqueous ratio maintained in each mixer is 10 to 12 whereas optimum extraction process requires an overall organic to aqueous ratio of 2. Therefore, a high volume of internal recirculation of organic is being arranged by the air-lift in mixers. For a smooth, continuous efficient extraction, mixer organic to aqueous ratio is a very critical parameter and it is required to be monitored periodically to take corrective actions during the operation by controlling the compressed air flow rate. Trials were conducted to select a suitable method of autocontrol of this phase ratio and a system has been designed for this purpose. (author). 3 figs., 1 tab.

Drug release from non-aqueous suspensions. II. The release of methylxanthines from paraffin suspensions

NARCIS (Netherlands)

Blaey, C.J. de; Fokkens, J.G.

1984-01-01

The release of 3 methylxanthines, i.e. caffeine, theobromine and theophylline, from suspensions in liquid paraffin to an aqueous phase was determined in an in vitro apparatus. The release rates were determined as a function of the pH of the aqueous phase. It was proved that the release process was

Effect of the Polymeric Stabilizer in the Aqueous Phase Fischer-Tropsch Synthesis Catalyzed by Colloidal Cobalt Nanocatalysts

Directory of Open Access Journals (Sweden)

Jorge A. Delgado

2017-03-01

Full Text Available A series of small and well defined cobalt nanoparticles were synthesized by the chemical reduction of cobalt salts in water using NaBH4 as a reducing agent and using various polymeric stabilizers. The obtained nanocatalysts of similar mean diameters (ca. 2.6 nm were fully characterized and tested in the aqueous phase Fischer-Tropsch Synthesis (AFTS. Interestingly, the nature and structure of the stabilizers used during the synthesis of the CoNPs affected the reduction degree of cobalt and the B-doping of these NPs and consequently, influenced the performance of these nanocatalysts in AFTS.

Aqueous phase synthesis of upconversion nanocrystals through layer-by-layer epitaxial growth for in vivo X-ray computed tomography

KAUST Repository

Li, Feifei

2013-05-21

Lanthanide-doped core-shell upconversion nanocrystals (UCNCs) have tremendous potential for applications in many fields, especially in bio-imaging and medical therapy. As core-shell UCNCs are mostly synthesized in organic solvents, tedious organic-aqueous phase transfer processes are usually needed for their use in bio-applications. Herein, we demonstrate the first example of one-step synthesis of highly luminescent core-shell UCNCs in the "aqueous" phase under mild conditions using innocuous reagents. A microwave-assisted approach allowed for layer-by-layer epitaxial growth of a hydrophilic NaGdF4 shell on NaYF4:Yb, Er cores. During this process, surface defects of the nanocrystals could be gradually passivated by the homogeneous shell deposition, resulting in obvious enhancement in the overall upconversion emission efficiency. In addition, the up-down conversion dual-mode luminescent NaYF4:Yb, Er@NaGdF4:Ce, Ln (Eu, Tb, Sm, Dy) nanocrystals were also synthesized to further validate the successful formation of the core-shell structure. More significantly, based on their superior solubility and stability in water solution, high upconversion efficiency and Gd-doped predominant X-ray absorption, the as-prepared NaYF4:Yb, Er@NaGdF4 core-shell UCNCs exhibited high contrast in in vitro cell imaging and in vivo X-ray computed tomography (CT) imaging, demonstrating great potential as multiplexed luminescent biolabels and CT contrast agents.

Br2 production from the heterogeneous reaction of gas-phase OH with aqueous salt solutions: Impacts of acidity, halide concentration, and organic surfactants.

Science.gov (United States)

Frinak, Elizabeth K; Abbatt, Jonathan P D

2006-09-07

This study reports the first laboratory measurement of gas-phase Br2 production from the reaction between gas-phase hydroxyl radicals and aqueous salt solutions. Experiments were conducted at 269 K in a rotating wetted-wall flow tube coupled to a chemical-ionization mass spectrometer for analysis of gas-phase components. From both pure NaBr solutions and mixed NaCl/NaBr solutions, the amount of Br2 released was found to increase with increasing acidity, whereas it was found to vary little with increasing concentration of bromide ions in the sample. For mixed NaCl/NaBr solutions, Br2 was formed preferentially over Cl2 unless the Br- levels in the solution were significantly depleted by OH oxidation, at which point Cl2 formation was observed. Presence of a surfactant in solution, sodium dodecyl sulfate, significantly suppressed the formation of Br2; this is the first indication that an organic surfactant can affect the rate of interfacial mass transfer of OH to an aqueous surface. The OH-mediated oxidation of bromide may serve as a source of active bromine in the troposphere and contribute to the subsequent destruction of ozone that proceeds in marine-influenced regions of the troposphere.

Removal of 2,4-Dichlorophenolyxacetic acid (2,4-D) herbicide in the aqueous phase using modified granular activated carbon

OpenAIRE

Dehghani, Mansooreh; Nasseri, Simin; Karamimanesh, Mojtaba

2014-01-01

Background Low cost 2,4-Dichlorophenolyxacetic acid (2,4-D) widely used in controlling broad-leafed weeds is frequently detected in water resources. The main objectives of this research were focused on evaluating the feasibility of using granular activated carbon modified with acid to remove 2,4-D from aqueous phase, determining its removal efficiency and assessing the adsorption kinetics. Results The present study was conducted at bench-scale method. The influence of different pH (3–9), the ...

Solid phase extraction of uranium and thorium on octadecyl bonded silica modified with Cyanex 302 from aqueous solutions

International Nuclear Information System (INIS)

Nilchi, A.; Shariati Dehaghan, T.; Rasouli Garmarodi, S.

2013-01-01

A simple and reliable method for rapid extraction and determination of uranium and thorium using octadecyl-bonded silica modified with Cyanex 302 is presented. Extraction efficiency and the influence of various parameters such as aqueous phase pH, flow rate of sample solution and amount of extractant has been investigated. The study showed that the extraction of uranium and thorium increase with increasing pH value and was found to be quantitative at pH 6; and the retention of ions was not affected significantly by the flow rate of sample solution. The extraction percent were found to be 89.55 and 86.27 % for uranium and thorium, respectively. The maximal capacity of the cartridges modified by 30 mg of Cyanex 302 was found to be 20 mg of uranium and thorium. The method was successfully applied to the extraction and determination of uranium and thorium in aqueous solutions. The percentage recovery of uranium and thorium in a number of natural as well as seawater samples of Iran were also investigated and found to be in the range of 85-95%. (author)

Huaier Aqueous Extract Induces Hepatocellular Carcinoma Cells Arrest in S Phase via JNK Signaling Pathway

Directory of Open Access Journals (Sweden)

Chengshuo Zhang

2015-01-01

Full Text Available Huaier aqueous extract, the main active constituent of Huaier proteoglycan, has antihepatocarcinoma activity in experimental and clinical settings. However, the potential and associated antihepatoma mechanisms of Huaier extract are not yet fully understood. Therefore, in this study, we aimed to elucidate the inhibitory proliferation effect of Huaier extract on apoptosis and cycle of HepG2 and Bel-7402 cells. Our data demonstrated that incubation with Huaier extract resulted in a marked decrease in cell viability dose-dependently. Flow cytometric analysis showed that a 48 h treatment of Huaier extract caused cell apoptosis. Typical apoptotic nucleus alterations were observed with fluorescence microscope after Hoechst staining. Immunoblot analysis further demonstrated that Huaier extract activated caspase 3 and PARP. Additionally, Huaier extract inhibited the activity of p-ERK, p-p38, and p-JNK in terms of MAPK. Furthermore, Huaier extract induced HCC cells arrest in S phase and decreased the cycle related protein expression of β-catenin and cyclin D1. Studies with JNK specific inhibitor, SP600125, showed that Huaier extract induced S phase arrest and decreased β-catenin and cyclin D1 expression via JNK signaling pathway. In conclusion, we verify that Huaier extract causes cell apoptosis and induces hepatocellular carcinoma cells arrest in S phase via JNK pathway, which advances our understanding on the molecular mechanisms of Huaier extract in hepatocarcinoma management.

Ionic liquid and aqueous two-phase extraction based on salting-out coupled with high-performance liquid chromatography for the determination of seven rare ginsenosides in Xue-Sai-Tong injection.

Science.gov (United States)

Li, Lan-Jie; Jin, Yong-Ri; Wang, Xiao-Zhong; Liu, Ying; Wu, Qian; Shi, Xiao-Lei; Li, Xu-Wen

2015-09-01

A method of ionic liquid salt aqueous two-phase extraction coupled with high-performance liquid chromatography has been developed for the analysis of seven rare ginsenosides including Rg6 , F4 , 20(S)-Rg3 , 20(R)-Rg3 , Rk3 , Rk1 , and Rg5 in Xue-Sai-Tong injection. The injection was mixed with ionic liquid 1-butyl-3-methylimidazolium bromide aqueous solution, and a mixture was obtained. With the addition of sodium dodecyl sulfate and dipotassium phosphate into the mixture, the aqueous two-phase mixture was formed after ultrasonic treatment and centrifuged. Rare ginsenosides were extracted into the upper phase. To obtain a high extraction factors, various influences were considered systematically, such as the volume of ionic liquid, the category and amount of salts, the amount of sodium dodecyl sulfate, the pH value of system, and the time of ultrasonic treatment. Under the optimal condition, rare ginsenosides in Xue-Sai-Tong injection were enriched and detected, the recoveries of seven rare ginsenosides ranged from 90.05 to 112.55%, while relative standard deviations were lower than 2.50%. The developed method was reliable, rapid and sensitive for the determination of seven rare ginsenosides in the injections. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deciphering the internal complexity of living cells with quantitative phase microscopy: a multiscale approach

Science.gov (United States)

Martinez-Torres, Cristina; Laperrousaz, Bastien; Berguiga, Lotfi; Boyer-Provera, Elise; Elezgaray, Juan; Nicolini, Franck E.; Maguer-Satta, Veronique; Arneodo, Alain; Argoul, Françoise

2015-09-01

The distribution of refractive indices (RIs) of a living cell contributes in a nonintuitive manner to its optical phase image and quite rarely can be inverted to recover its internal structure. The interpretation of the quantitative phase images of living cells remains a difficult task because (1) we still have very little knowledge on the impact of its internal macromolecular complexes on the local RI and (2) phase changes produced by light propagation through the sample are mixed with diffraction effects by the internal cell bodies. We propose to implement a two-dimensional wavelet-based contour chain detection method to distinguish internal boundaries based on their greatest optical path difference gradients. These contour chains correspond to the highest image phase contrast and follow the local RI inhomogeneities linked to the intracellular structural intricacy. Their statistics and spatial distribution are the morphological indicators suited for comparing cells of different origins and/or to follow their transformation in pathologic situations. We use this method to compare nonadherent blood cells from primary and laboratory culture origins and to assess the internal transformation of hematopoietic stem cells by the transduction of the BCR-ABL oncogene responsible for the chronic myelogenous leukemia.

Cold-induced aqueous acetonitrile phase separation: A salt-free way to begin quick, easy, cheap, effective, rugged, safe.

Science.gov (United States)

Shao, Gang; Agar, Jeffrey; Giese, Roger W

2017-07-14

Cooling a 1:1 (v/v) solution of acetonitrile and water at -16° C is known to result in two clear phases. We will refer to this event as "cold-induced aqueous acetonitrile phase separation (CIPS)". On a molar basis, acetonitrile is 71.7% and 13.6% in the upper and lower phases, respectively, in our study. The phase separation proceeds as a descending cloud of microdroplets. At the convenient temperature (typical freezer) employed here the lower phase is rather resistant to solidification, although it emerges from the freezer as a solid if various insoluble matter is present at the outset. In a preliminary way, we replaced the initial (salting-out) step of a representative QuEChERS procedure with CIPS, applying this modified procedure ("CIPS-QuEChERS") to a homogenate of salmon (and partly to beef). Three phases resulted, where only the upper, acetonitrile-rich phase is a liquid (that is completely clear). The middle phase comprises ice and precipitated lipids, while the lower phase is the residual matrix of undissolved salmon or meat. Treating the upper phase from salmon, after isolation, with anhydrous MgSO 4 and C18-Si (typical QuEChERS dispersive solid phase extraction sorbents), and injecting into a GC-MS in a nontargeted mode, gives two-fold more preliminary hits for chemicals, and also number of spiked pesticides recovered, relative to that from a comparable QuEChERS method. In part, this is because of much higher background signals in the latter case. Further study of CIPS-QuEChERS is encouraged, including taking advantage of other QuERChERS conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

Integrated method of thermosensitive triblock copolymer-salt aqueous two phase extraction and dialysis membrane separation for purification of lycium barbarum polysaccharide.

Science.gov (United States)

Wang, Yun; Hu, Xiaowei; Han, Juan; Ni, Liang; Tang, Xu; Hu, Yutao; Chen, Tong

2016-03-01

A polymer-salt aqueous two-phase system (ATPS) consisting of thermosensitive copolymer ethylene-oxide-b-propylene-oxide-b-ethylene-oxide (EOPOEO) and NaH2PO4 was employed in deproteinization for lycium barbarum polysaccharide (LBP). The effects of salt type and concentration, EOPOEO concentration, amount of crude LBP solution and temperature were studied. In the primary extraction process, LBP was preferentially partitioned to the bottom (salt-rich) phase with high recovery ratio of 96.3%, while 94.4% of impurity protein was removed to the top (EOPOEO-rich) phase. Moreover, the majority of pigments could be discarded to top phase. After phase-separation, the LBP in the bottom phase was further purified by dialysis membrane to remove salt and other small molecular impurities. The purity of LBP was enhanced to 64%. Additionally, the FT-IR spectrum was used to identify LBP. EOPOEO was recovered by a temperature-induced separation, and reused in a new ATPS. An ideal extraction and recycle result were achieved. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of HCl and HNO3 on the oxidation of toluene to benzaldehyde by H2O2 over TS-1 modified with Al in aqueous phase

Directory of Open Access Journals (Sweden)

Paricha Pongjirawat

2014-09-01

Full Text Available This research studies effects of HCl and HNO3 in aqueous solution on the oxidation reaction between toluene and hydrogen peroxide to benzaldehyde over titanium silicalite-1 catalyst modified with Al. The reaction was carried out at reaction temperature 120°C in a pressurized autoclave reactor. The research found that the addition of HCl and HNO3 not only increases the concentration of toluene in the aqueous phase but also increases the formation of benzaldehyde as main product in the reaction.

Homogenization of linear viscoelastic three phase media: internal variable formulation versus full-field computation

International Nuclear Information System (INIS)

Blanc, V.; Barbie, L.; Masson, R.

2011-01-01

Homogenization of linear viscoelastic heterogeneous media is here extended from two phase inclusion-matrix media to three phase inclusion-matrix media. Each phase obeying to a compressible Maxwellian behaviour, this analytic method leads to an equivalent elastic homogenization problem in the Laplace-Carson space. For some particular microstructures, such as the Hashin composite sphere assemblage, an exact solution is obtained. The inversion of the Laplace-Carson transforms of the overall stress-strain behaviour gives in such cases an internal variable formulation. As expected, the number of these internal variables and their evolution laws are modified to take into account the third phase. Moreover, evolution laws of averaged stresses and strains per phase can still be derived for three phase media. Results of this model are compared to full fields computations of representative volume elements using finite element method, for various concentrations and sizes of inclusion. Relaxation and creep test cases are performed in order to compare predictions of the effective response. The internal variable formulation is shown to yield accurate prediction in both cases. (authors)

The IUPAC aqueous and non-aqueous experimental pKa data repositories of organic acids and bases.

Science.gov (United States)

Slater, Anthony Michael

2014-10-01

Accurate and well-curated experimental pKa data of organic acids and bases in both aqueous and non-aqueous media are invaluable in many areas of chemical research, including pharmaceutical, agrochemical, specialty chemical and property prediction research. In pharmaceutical research, pKa data are relevant in ligand design, protein binding, absorption, distribution, metabolism, elimination as well as solubility and dissolution rate. The pKa data compilations of the International Union of Pure and Applied Chemistry, originally in book form, have been carefully converted into computer-readable form, with value being added in the process, in the form of ionisation assignments and tautomer enumeration. These compilations offer a broad range of chemistry in both aqueous and non-aqueous media and the experimental conditions and original reference for all pKa determinations are supplied. The statistics for these compilations are presented and the utility of the computer-readable form of these compilations is examined in comparison to other pKa compilations. Finally, information is provided about how to access these databases.

Study of surface activity of piroxicam at the interface of palm oil esters and various aqueous phases.

Science.gov (United States)

Abdulkarim, Muthanna Fawzy; Abdullah, Ghassan Zuhair; Chitneni, Mallikarjun; Yam, Mun Fei; Mahdi, Elrashid Saleh; Salman, Ibrahim Muhammad; Ameer, Omar Ziad; Sattar, Munavvar Abdul; Basri, Mahiran; Noor, Azmin Mohd

2012-04-01

The surface activity of some non-steroidal anti-inflammatory agents like ibuprofen was investigated extensively. This fact has attracted the researchers to extend this behavior to other agents like piroxicam. Piroxicam molecules are expected to orient at the interface of oil and aqueous phase. The aim of this study was, firstly, to assess the surface and interfacial tension behaviour of newly synthesised palm oil esters and various pH phosphate buffers. Furthermore, the surface and interfacial tension activity of piroxicam was studied. All the measurements of surface and interfacial tension were made using the tensiometer. The study revealed that piroxicam has no effect on surface tension values of all pH phosphate buffers and palm oil esters. Similarly, various concentrations of piroxicam did not affect the interfacial tensions between the oil phase and the buffer phases. Accordingly, the interfacial tension values of all mixtures of oil and phosphate buffers were considerably high which indicates the immiscibility. It could be concluded that piroxicam has no surface activity. Additionally, there is no surface pressure activity of piroxicam at the interface of plam oil esters and phosphate buffers in the presence of Tweens and Spans.

Purification of pectinase from mango (Mangifera indica L. cv. Chokanan) waste using an aqueous organic phase system: a potential low cost source of the enzyme.

Science.gov (United States)

Amid, Mehrnoush; Abdul Manap, Mohd Yazid; Mustafa, Shuhaimi

2013-07-15

As a novel method of purification, an aqueous organic phase system (AOPS) was employed to purify pectinase from mango waste. The effect of different parameters, such as the alcohol concentration (ethanol, 1-propanol, and 2-propanol), the salt type and concentration (ammonium sulfate, potassium phosphate and sodium citrate), the feed stock crude load, the aqueous phase pH and NaCl concentration, were investigated in the recovery of pectinase from mango peel. The partition coefficient (K), selectivity (S), purification factor (PF) and yield (Y, %) were investigated in this study as important parameters for the evaluation of enzyme recovery. The desirable partition efficiency for pectinase purification was achieved in an AOPS of 19% (w/w) ethanol and 22% (w/w) potassium phosphate in the presence of 5% (w/w) NaCl at pH 7.0. Based on the system, the purification factor of pectinase was enhanced 11.7, with a high yield of 97.1%. Copyright © 2013 Elsevier B.V. All rights reserved.

GEOSURF: a computer program for modeling adsorption on mineral surfaces from aqueous solution

Science.gov (United States)

Sahai, Nita; Sverjensky, Dimitri A.

1998-11-01

A new program, GEOSURF, has been developed for calculating aqueous and surface speciation consistent with the triple-layer model of surface complexation. GEOSURF is an extension of the original programs MINEQL, MICROQL and HYDRAQL. We present, here, the basic algorithm of GEOSURF along with a description of the new features implemented. GEOSURF is linked to internally consistent data bases for surface species (SURFK.DAT) and for aqueous species (AQSOL.DAT). SURFK.DAT contains properties of minerals such as site densities, and equilibrium constants for adsorption of aqueous protons and electrolyte ions on a variety of oxides and hydroxides. The Helgeson, Kirkham and Flowers version of the extended Debye-Huckel Equation for 1:1 electrolytes is implemented for calculating aqueous activity coefficients. This permits the calculation of speciation at ionic strengths greater than 0.5 M. The activity of water is computed explicitly from the osmotic coefficient of the solution, and the total amount of electrolyte cation (or anion) is adjusted to satisfy the electroneutrality condition. Finally, the use of standard symbols for chemical species rather than species identification numbers is included to facilitate use of the program. One of the main limitations of GEOSURF is that aqueous and surface speciation can only be calculated at fixed pH and at fixed concentration of total adsorbate. Thus, the program cannot perform reaction-path calculations: it cannot determine whether or not a solution is over- or under-saturated with respect to one or more solid phases. To check the proper running of GEOSURF, we have compared results generated by GEOSURF with those from two other programs, HYDRAQL and EQ3. The Davies equation and the "bdot" equation, respectively, are used in the latter two programs for calculating aqueous activity coefficients. An example of the model fit to experimental data for rutile in 0.001 M-2.0 M NaNO 3 is included.

Application of mercapto-silica polymerized high internal phase emulsions for the solid-phase extraction and preconcentration of trace lead(II).

Science.gov (United States)

Su, Rihui; Ruan, Guihua; Chen, Zhengyi; Du, Fuyou; Li, Jianping

2015-12-01

A new class of solid-phase extraction column prepared with grafted mercapto-silica polymerized high internal phase emulsion particles was used for the preconcentration of trace lead. First, mercapto-silica polymerized high internal phase emulsion particles were synthesized by using high internal phase emulsion polymerization and carefully assembled in a polyethylene syringe column. The influences of various parameters including adsorption pH value, adsorption and desorption solvents, flow rate of the adsorption and desorption procedure were optimized, respectively, and the suitable uploading sample volumes, adsorption capacity, and reusability of solid phase extraction column were also investigated. Under the optimum conditions, Pb(2+) could be preconcentrated quantitatively over a wide pH range (2.0-5.0). In the presence of foreign ions, such as Na(+) , K(+) , Ca(2+) , Zn(2+) , Mg(2+) , Cu(2+) , Fe(2+) , Cd(2+) , Cl(-) and NO3 (-) , Pb(2+) could be recovered successfully. The prepared solid-phase extraction column performed with high stability and desirable durability, which allowed more than 100 replicate extractions without measurable changes of performance. The feasibility of the developed method was further validated by the extraction of Pb(2+) in rice samples. At three spiked levels of 40.0, 200 and 800 μg/kg, the average recoveries for Pb(2+) in rice samples ranged from 87.3 to 105.2%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Separation of uranium from aqueous solutions using calix[6]arenes in liquid-liquid extraction as well as solid phase extraction

International Nuclear Information System (INIS)

Schmeide, K.; Geipel, G.; Bernhard, G.

2004-11-01

The suitability of different calyx[n] arene types for uranyl extraction from liquid solutions was examined by means of liquid-liquid extraction using aqueous phases and organic solvents of varying compositions. It was found that COOH-derivatised calyx[6] arenes have good extraction properties and can even be used in the acid pH range. The use of calixarene-modified fleeces for the separation of uranyl from aqueous phases was examined in batch experiments with pH and uranyl concentration as variables and in the presence or absence of competing ions. The results showed that calixarene-modified fleeces can be used for uranium separation starting from pH 4. At pH 5, up to a maximum of 7.6 x 10 -7 mol uranium can be bound per 1 g of calixarene-modified fleece. The separation of uranyl from synthetic pit waters was examined as a means of testing the separation capacity of calixarene-modified fleeces in environmentally sensitive waters. Studies on the reversibility of uranium bonding to calixarene-treated polyester fleeces have shown that under environmentally realistic conditions (neutral pH range) the uranium is firmly bound to the calixarene-modified fleeces and cannot be mobilised. By contrast, in acidic environments calixarene-modified fleeces are capable of near-complete regeneration. Such regenerated textile filter materials can then be used for further uranium separation cycles [de

Internal friction and linear expansion coefficient in zirconium and cobalt within the range of phase transitions

International Nuclear Information System (INIS)

Boyarskij, S.V.

1986-01-01

Experimental results are presented for internal friction and linear expansion coefficient at zirconium and cobalt in the temperature range from 440 K to the point of the phase transition of the first kind (1138 K for Zr and 706 for Co). Anomalous changes of the internal friction and linear expansion coefficient in the phase transition region are found. Theoretical considerations are given to explain the sharp decrease of the internal friction as temperature approaches the phase transition point

Aqueous phase transfer of InP/ZnS nanocrystals conserving fluorescence and high colloidal stability.

Science.gov (United States)

Tamang, Sudarsan; Beaune, Grégory; Texier, Isabelle; Reiss, Peter

2011-12-27

Small thiol-containing amino acids such as cysteine are appealing surface ligands for transferring semiconductor quantum dots (QDs) from organic solvents to the aqueous phase. They provide a compact hydrodynamic diameter and low nonspecific binding in biological environment. However, cysteine-capped QDs generally exhibit modest colloidal stability in water and their fluorescence quantum yield (QY) is significantly reduced as compared to organics. We demonstrate that during phase transfer the deprotonation of the thiol group by carefully adjusting the pH is of crucial importance for increasing the binding strength of cysteine to the QD surface. As a result, the colloidal stability of cysteine-capped InP/ZnS core/shell QDs is extended from less than one day to several months. The developed method is of very general character and can be used also with other hydrophilic thiols and various other types of QDs, e.g., CdSe/CdS/ZnS and CuInS(2)/ZnS QDs as well as CdSe and CdSe/CdS nanorods. We show that the observed decrease of QY upon phase transfer with cysteine is related to the generation of cysteine dimer, cystine. This side-reaction implies the formation of disulfide bonds, which efficiently trap photogenerated holes and inhibit radiative recombination. On the other hand, this process is not irreversible. By addition of an appropriate reducing agent, tris(2-carboxyethyl)phosphine hydrochloride (TCEP), the QY can be partially recovered. When TCEP is already added during the phase transfer, the QY of cysteine-capped InP/ZnS QDs can be maintained almost quantitatively. Finally, we show that penicillamine is a promising alternative to cysteine for the phase transfer of QDs, as it is much less prone to disulfide formation.

NASA Physical Sciences - Presentation to Annual Two Phase Heat Transfer International Topical Team Meeting

Science.gov (United States)

Chiaramonte, Francis; Motil, Brian; McQuillen, John

2014-01-01

The Two-phase Heat Transfer International Topical Team consists of researchers and members from various space agencies including ESA, JAXA, CSA, and RSA. This presentation included descriptions various fluid experiments either being conducted by or planned by NASA for the International Space Station in the areas of two-phase flow, flow boiling, capillary flow, and crygenic fluid storage.

Partition Coefficients of Amino Acids, Peptides, and Enzymes in Dextran + Poly(Ethylene Glycol) + Water Aqueous Two-Phase Systems

Energy Technology Data Exchange (ETDEWEB)

Kakisaka, Keijiro.; Shindo, Takashi.; Iwai, Yoshio.; Arai, Yasuhiko. [Kyushu University, Fukuoka (Japan). Department of Chemical Systems and Engineering

1998-12-01

Partition coefficients are measured for five amino acids(aspartic acid, asparagine, methionine, cysteine and histidine) and tow peptides(glycyl-glycine and hexa-glycine) in dextran + poly(ethylene glycol) + water aqueous two-phase system. The partition coefficients of the amino acids and peptides are aorrelated using the osmotic virial equation. The interaction coefficients contained in the equation can be calculated by hydrophilic group parameters. The partition coefficients of {alpha}-amylase calculated by the osmotic virial equation with the hydrophilic group parameters are in fairly good agreement with the experimental data, though a relatively large discrepancy is shown for {beta}-amylase. (author)

Partition Coefficients of Amino Acids, Peptides, and Enzymes in Dextran + Poly(Ethylene Glycol) + Water Aqueous Two-Phase Systems

Energy Technology Data Exchange (ETDEWEB)

Kakisaka, Keijiro.; Shindo, Takashi.; Iwai, Yoshio.; Arai, Yasuhiko. (Kyushu University, Fukuoka (Japan). Department of Chemical Systems and Engineering)

1998-12-01

Partition coefficients are measured for five amino acids(aspartic acid, asparagine, methionine, cysteine and histidine) and tow peptides(glycyl-glycine and hexa-glycine) in dextran + poly(ethylene glycol) + water aqueous two-phase system. The partition coefficients of the amino acids and peptides are aorrelated using the osmotic virial equation. The interaction coefficients contained in the equation can be calculated by hydrophilic group parameters. The partition coefficients of [alpha]-amylase calculated by the osmotic virial equation with the hydrophilic group parameters are in fairly good agreement with the experimental data, though a relatively large discrepancy is shown for [beta]-amylase. (author)

Characterization of aqueous two phase systems by combining lab-on-a-chip technology with robotic liquid handling stations.

Science.gov (United States)

Amrhein, Sven; Schwab, Marie-Luise; Hoffmann, Marc; Hubbuch, Jürgen

2014-11-07

Over the last decade, the use of design of experiment approaches in combination with fully automated high throughput (HTP) compatible screenings supported by robotic liquid handling stations (LHS), adequate fast analytics and data processing has been developed in the biopharmaceutical industry into a strategy of high throughput process development (HTPD) resulting in lower experimental effort, sample reduction and an overall higher degree of process optimization. Apart from HTP technologies, lab-on-a-chip technology has experienced an enormous growth in the last years and allows further reduction of sample consumption. A combination of LHS and lab-on-a-chip technology is highly desirable and realized in the present work to characterize aqueous two phase systems with respect to tie lines. In particular, a new high throughput compatible approach for the characterization of aqueous two phase systems regarding tie lines by exploiting differences in phase densities is presented. Densities were measured by a standalone micro fluidic liquid density sensor, which was integrated into a liquid handling station by means of a developed generic Tip2World interface. This combination of liquid handling stations and lab-on-a-chip technology enables fast, fully automated, and highly accurate density measurements. The presented approach was used to determine the phase diagram of ATPSs composed of potassium phosphate (pH 7) and polyethylene glycol (PEG) with a molecular weight of 300, 400, 600 and 1000 Da respectively in the presence and in the absence of 3% (w/w) sodium chloride. Considering the whole ATPS characterization process, two complete ATPSs could be characterized within 24h, including four runs per ATPS for binodal curve determination (less than 45 min/run), and tie line determination (less than 45 min/run for ATPS preparation and 8h for density determination), which can be performed fully automated over night without requiring man power. The presented methodology provides

Some recent trends in computer simulations of aqueous double layers

International Nuclear Information System (INIS)

Spohr, E.

2003-01-01

Recent molecular simulations of the electric double layer between an aqueous and a metallic phase are reviewed. Several trends in the field can be identified: (i) the increasing use of ab initio simulation methods, most notably the Car-Parrinello method, allows to combine a statistical mechanical description of the double layer with a description of elementary chemical processes on the electronic structure level; (ii) the application of free-energy methods in one and (recently) two dimensions to describe chemical reactivity within and beyond the framework of the Marcus theory of electron transfer; and (iii) at high concentrations, direct simulations of two-phase systems with an aqueous solution and a charged or uncharged solid phase or surface can model the entire double layer region

Liquid–liquid equilibria in the quinary aqueous two-phase system of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol: Experimental investigation and thermodynamic modeling

Energy Technology Data Exchange (ETDEWEB)

Hekayati, Javad; Roosta, Aliakbar, E-mail: aa.roosta@sutech.ac.ir; Javanmardi, Jafar

2016-02-10

Highlights: • Quinary LLE phase equilibria involving PEG 6000 + Na{sub 2}SO{sub 4} + H{sub 2}O + glucose + ethanol. • Favorable partition coefficients of ethanol and glucose. • Satisfactory correlation of the LLE experimental data with the original NRTL model. • Root mean squared deviations (RMSDs) of less than 0.6%. - Abstract: Extractive fermentation processes involving aqueous two-phase systems (ATPSs) are considered as viable means of overcoming the problems associated with product inhibition. Practical development of these processes requires accurate knowledge of the liquid–liquid equilibrium (LLE) of the ATPS forming components alongside the substrate and product of the fermentation process. In this work, the quinary aqueous two-phase LLE of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol have been experimentally determined at 298.15 K using spectrophotometric methods. The resulting LLE data were then satisfactorily correlated by the non-random two-liquid (NRTL) activity coefficient model based on mass fractions. In doing so, the binary energy interaction parameters of the NRTL activity coefficient model were obtained and reported. Calculated RMS deviations below 0.6% demonstrate that the original NRTL activity coefficient model can accurately correlate the LLE data of the quinary aqueous biphasic system of interest.

Liquid–liquid equilibria in the quinary aqueous two-phase system of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol: Experimental investigation and thermodynamic modeling

International Nuclear Information System (INIS)

Hekayati, Javad; Roosta, Aliakbar; Javanmardi, Jafar

2016-01-01

Highlights: • Quinary LLE phase equilibria involving PEG 6000 + Na_2SO_4 + H_2O + glucose + ethanol. • Favorable partition coefficients of ethanol and glucose. • Satisfactory correlation of the LLE experimental data with the original NRTL model. • Root mean squared deviations (RMSDs) of less than 0.6%. - Abstract: Extractive fermentation processes involving aqueous two-phase systems (ATPSs) are considered as viable means of overcoming the problems associated with product inhibition. Practical development of these processes requires accurate knowledge of the liquid–liquid equilibrium (LLE) of the ATPS forming components alongside the substrate and product of the fermentation process. In this work, the quinary aqueous two-phase LLE of poly(ethylene glycol) 6000 + sodium sulfate + water in the presence of glucose and ethanol have been experimentally determined at 298.15 K using spectrophotometric methods. The resulting LLE data were then satisfactorily correlated by the non-random two-liquid (NRTL) activity coefficient model based on mass fractions. In doing so, the binary energy interaction parameters of the NRTL activity coefficient model were obtained and reported. Calculated RMS deviations below 0.6% demonstrate that the original NRTL activity coefficient model can accurately correlate the LLE data of the quinary aqueous biphasic system of interest.

Stability indicating HPLC-DAD method for analysis of Ketorolac binary and ternary mixtures in eye drops: Quantitative analysis in rabbit aqueous humor.

Science.gov (United States)

El Yazbi, Fawzy A; Hassan, Ekram M; Khamis, Essam F; Ragab, Marwa A A; Hamdy, Mohamed M A

2017-11-15

Ketorolac tromethamine (KTC) with phenylephrine hydrochloride (PHE) binary mixture (mixture 1) and their ternary mixture with chlorpheniramine maleate (CPM) (mixture 2) were analyzed using a validated HPLC-DAD method. The developed method was suitable for the in vitro as well as quantitative analysis of the targeted mixtures in rabbit aqueous humor. The analysis in dosage form (eye drops) was a stability indicating one at which drugs were separated from possible degradation products arising from different stress conditions (in vitro analysis). For analysis in aqueous humor, Guaifenesin (GUF) was used as internal standard and the method was validated according to FDA regulation for analysis in biological fluids. Agilent 5 HC-C18(2) 150×4.6mm was used as stationary phase with a gradient eluting solvent of 20mM phosphate buffer pH 4.6 containing 0.2% triethylamine and acetonitrile. The drugs were resolved with retention times of 2.41, 5.26, 7.92 and 9.64min for PHE, GUF, KTC and CPM, respectively. The method was sensitive and selective to analyze simultaneously the three drugs in presence of possible forced degradation products and dosage form excipients (in vitro analysis) and also with the internal standard, in presence of aqueous humor interferences (analysis in biological fluid), at a single wavelength (261nm). No extraction procedure was required for analysis in aqueous humor. The simplicity of the method emphasizes its capability to analyze the drugs in vivo (in rabbit aqueous humor) and in vitro (in pharmaceutical formulations). Copyright © 2017 Elsevier B.V. All rights reserved.

Separation of active laccases from Pleurotus sapidus culture supernatant using aqueous two-phase systems in centrifugal partition chromatography.

Science.gov (United States)

Schwienheer, C; Prinz, A; Zeiner, T; Merz, J

2015-10-01

For the production of bio active compounds, e.g., active enzymes or antibodies, a conserved purification process with a minimum loss of active compounds is necessary. In centrifugal partition chromatography (CPC), the separation effect is based on the different distribution of the components to be separated between two immiscible liquid phases. Thereby, one liquid phase is kept stationary in chambers by a centrifugal field and the mobile phase is pumped through via connecting ducts. Aqueous two phase systems (ATPS) are known to provide benign conditions for biochemical products and seem to be promising when used in CPC for purification tasks. However, it is not known if active biochemical compounds can "survive" the conditions in a CPC where strong shear forces can occur due to the two-phasic flow under centrifugal forces. Therefore, this aspect has been faced within this study by the separation of active laccases from a fermentation broth of Pleurotus sapidus. After selecting a suitable ATPS and operating conditions, the activity yield was calculated and the preservation of the active enzymes could be observed. Therefore, CPC could be shown as potentially suitable for the purification of bio-active compounds. Copyright © 2015 Elsevier B.V. All rights reserved.

Ionic liquid ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of the aqueous phase for preconcentration of heavy metals ions prior to determination by LC-UV.

Science.gov (United States)

Werner, Justyna

2018-05-15

Ionic liquid ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of the aqueous phase was used for preconcentration of Ni 2+ , Co 2+ , Cd 2+ , Cu 2+ , Pb 2+ in natural water samples prior to liquid chromatography with UV detection. In the proposed method, the ammonium pyrrolidinedithiocarbamate was used as a complexing agent and the phosphonium ionic liquid trihexyl(tetradecyl)phosphonium bis[(2,4,4-trimethyl)pentyl]phosphinate (Cyphos IL 104) was used as an extractant. Ultrasound energy was used to disperse the extractant in the aqueous phase. After microextraction, the ionic liquid and aqueous phases were separated by centrifugation. Then the aqueous phase was frozen and the lighter than water ionic liquid phase containing metal ions complexes with pyrrolidinedithiocarbamate was separated and dissolved in a small volume of methanol prior to injection into the liquid chromatograph. Several parameters including the volume of extractant, the pH of the sample, the concentration of complexing agent, the time of ultrasound energy treatment, the time and speed of centrifugation and the effect of ionic strength were optimized. Under the optimized conditions (10 µL of Cyphos IL 104, pH = 5, 0.3% w/v ammonium pyrrolidinedithiocarbamate, 60 s of ultrasound use, 5 min/5000 rpm (2516×g) of centrifugation, 2.0 mg of NaCl), preconcentration factors were 211, 210, 209, 207 and 211 for Ni 2+ , Co 2+ , Cd 2+ , Cu 2+ and Pb 2+ respectively. Linearity was observed in the ranges 0.2-75.0 µg L -1 for Pb 2+ , Cd 2+ , Co 2+ and 0.5-100.0 µg L -1 for Cu 2+ , Ni 2+ . The limits of detection were 0.03 µg L -1 for Ni 2+ , 0.03 µg L -1 for Co 2+ , 0.03 µg L -1 for Cd 2+ , 0.02 µg L -1 for Cu 2+ , 0.02 µg L -1 for Pb 2+ , respectively. The accuracy of this method was evaluated by preconcentration and determination of Ni 2+ , Co 2+ , Cd 2+ , Cu 2+ , Pb 2+ in certified reference materials (TMRAIN-04 and NIST 1643e

Infiltration characteristics of non-aqueous phase liquids in undisturbed loessal soil cores.

Science.gov (United States)

Wang, Yunqiang; Shao, Ming'an

2009-01-01

The widespread contamination of soils and aquifers by non-aqueous phase liquids (NAPL), such as crude oil, poses serious environmental and health hazards globally. Understanding the infiltration characteristics of NAPL in soil is crucial in mitigating or remediating soil contamination. The infiltration characteristics of crude and diesel oils into undisturbed loessal soil cores, collected in polymethyl methacrylate cylindrical columns, were investigated under a constant fluid head (3 cm) of either crude oil or diesel oil. The infiltration rate of both crude and diesel oils decreased exponentially as wetting depth increased with time. Soil core size and bulk density both had significant effects on NAPL infiltration through the undisturbed soil cores; a smaller core size or a greater bulk density could reduce oil penetration to depth. Compacting soil in areas susceptible to oil spills may be an effective stratage to reduce contamination. The infiltration of NAPL into soil cores was spatially anisotropic and heterogeneous, thus recording the data at four points on the soil core is a good stratage to improve the accuracy of experimental results. Our results revealed that crude and diesel oils, rather than their components, have a practical value for remediation of contaminated loessal soils.

Non-aqueous heavy oil extraction from oil sand

Energy Technology Data Exchange (ETDEWEB)

Bohnert, George [National Nuclear Security Administration (United States)

2011-07-01

The Kansas City plant operated by Honeywell has a long history of working with DOE NNSA on engineering and manufacturing services supporting national security requirements. The plant has developed a non-aqueous method for heavy oil extraction from oil sands. This method is environmentally friendly as it does not use any external body of water, which would normally be contaminated in the conventional method. It is a 2 phase process consisting of terpene, limonene or alpha pinene, and carbon dioxide. The CO2 and terpene phases are both closed loop systems which minimizes material loss. The limonene and alpha pinene are both naturally derived solvents that come from citrus sources or pine trees respectively. Carbon dioxide is an excellent co-solvent with terpene. There is also a possibility for heat loss recovery during the distillation phase. This process produces clean dry sand. Laboratory tests have concluded that this using non-aqueous liquids process works effectively.

Solid-phase extraction element based on epoxy polymer monolith for determination of polar organic compounds in aqueous media.

Science.gov (United States)

Takahashi, Tadashi; Odagiri, Kayo; Watanabe, Atsushi; Watanabe, Chuichi; Kubo, Takuya; Hosoya, Ken

2011-10-01

A solid-phase extraction element based on epoxy polymer monolith was fabricated for sorptive enrichment of polar compounds from liquid and gaseous samples. After ultrasonication of the element in an aqueous solution for a given period of time, the thermal desorption (TD) using a pyrolyzer with gas chromatography/mass spectrometry (GC/MS), in which TD temperature was programmed from 50 to 250 °C for the analytes absorbed in the element, was used to evaluate the element for basic extraction performance using the aqueous standard mixtures consisting of compounds having varied polarities such as hexanol, isoamyl acetate, linalool, furfural and decanoic acid, in concentrations ranging from 10 μg/L to 1 mg/L. Excellent linear relationships were observed for all compounds in the standard mixture, except decanoic acid. In the extraction of beverages such as red wine, the extraction element showed stronger adsorption characteristics for polar compounds such as alcohols and acids than a non-polar polydimethylsiloxane-based element. This feature is derived from the main polymer structure along with hydroxyl and amino groups present in the epoxy-based monolith polymer matrix. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Secondary Organic Aerosol Produced from Aqueous Reactions of Phenols in Fog Drops and Deliquesced Particles

Science.gov (United States)

Smith, J.; Anastasio, C.

2014-12-01

The formation and evolution of secondary organic aerosol (SOA) in atmospheric condensed phases (i.e., aqueous SOA) can proceed rapidly, but relatively little is known of the important aqueous SOA precursors or their reaction pathways. In our work we are studying the aqueous SOA formed from reactions of phenols (phenol, guaiacol, and syringol), benzene-diols (catechol, resorcinol, and hydroquinone), and phenolic carbonyls (e.g., vanillin and syringaldehyde). These species are potentially important aqueous SOA precursors because they are released in large quantities from biomass burning, have high Henry's Law constants (KH = 103 -109 M-1 atm-1) and are rapidly oxidized. To evaluate the importance of aqueous reactions of phenols as a source of SOA, we first quantified the kinetics and SOA mass yields for 11 phenols reacting via direct photodegradation, hydroxyl radical (•OH), and with an excited organic triplet state (3C*). In the second step, which is the focus of this work, we use these laboratory results in a simple model of fog chemistry using conditions during a previously reported heavy biomass burning event in Bakersfield, CA. Our calculations indicate that under aqueous aerosol conditions (i.e., a liquid water content of 100 μg m-3) the rate of aqueous SOA production (RSOA(aq)) from phenols is similar to the rate in the gas phase. In contrast, under fog/cloud conditions the aqueous RSOA from phenols is 10 times higher than the rate in the gas phase. In both of these cases aqueous RSOA is dominated by the oxidation of phenols by 3C*, followed by direct photodegradation of phenolic carbonyls, and then •OH oxidation. Our results suggest that aqueous oxidation of phenols is a significant source of SOA during fog events and also during times when deliquesced aerosols are present.

Two-liquid-phase boundaries and critical phenomena at 275 to 4000C for high-temperature aqueous potassium phosphate and sodium phosphate solutions. Potential applications for steam generators

International Nuclear Information System (INIS)

Marshall, W.L.

1982-01-01

Two-liquid-phase boundaries at temperatures between 275 and 400 0 C were determined for potassium phosphate and sodium phosphate aqueous solutions for compositions from 0 to 60 wt % dissolved salt. The stoichiometric mole ratios, K/PO 4 or Na/PO 4 , were varied from 1.00 to 2.12 and from 1.00 to 2.16 for the potassium and sodium systems, respectively. Liquid-vapor critical temperatures were also determined for most of the dilute liquid phases that formed. The minimum temperatures (below which a single solution existed) of two-liquid-phase formation were 360 0 C for the potassium system and 279 0 C for the sodium system at mole ratios of 2.00 and 2.16, respectively. For the sodium system at mole ratios greater than 2.16, solids crystallized at lower temperatures as expected from earlier studies. In contrast, potassium solutions that were explored at mole ratios from 2.12 to 3.16 and at temperatures below 360 0 C did not produce solid phases or liquid-liquid immisibilities. Aside from the generally unusual observations of two immiscible liquids in an aqueous inorganic salt system, the results could possibly be applied to the use of phosphate additives in steam power generators

Non-aqueous nanoporous gold based supercapacitors with high specific energy

International Nuclear Information System (INIS)

Hou, Ying; Chen, Luyang; Hirata, Akihiko; Fujita, Takeshi; Chen, Mingwei

2016-01-01

In this study, we report that the supercapacitor performance of polypyrrole (PPy) in non-aqueous electrolytes can be dramatically improved by highly conductive nanoporous gold which acts as both the support of active PPy and the current collector of supercapacitors. The excellent electronic conductivity, rich porous structure and large surface area of the nanoporous electrodes give rise to a high specific capacitance and low internal resistance in non-aqueous electrolytes. Combining with a wide working potential window of ~ 2 V, the non-aqueous PPy-based supercapacitors show an extraordinary energy density and power density.

Coupled enzyme reactions performed in heterogeneous reaction media: experiments and modeling for glucose oxidase and horseradish peroxidase in a PEG/citrate aqueous two-phase system.

Science.gov (United States)

Aumiller, William M; Davis, Bradley W; Hashemian, Negar; Maranas, Costas; Armaou, Antonios; Keating, Christine D

2014-03-06

The intracellular environment in which biological reactions occur is crowded with macromolecules and subdivided into microenvironments that differ in both physical properties and chemical composition. The work described here combines experimental and computational model systems to help understand the consequences of this heterogeneous reaction media on the outcome of coupled enzyme reactions. Our experimental model system for solution heterogeneity is a biphasic polyethylene glycol (PEG)/sodium citrate aqueous mixture that provides coexisting PEG-rich and citrate-rich phases. Reaction kinetics for the coupled enzyme reaction between glucose oxidase (GOX) and horseradish peroxidase (HRP) were measured in the PEG/citrate aqueous two-phase system (ATPS). Enzyme kinetics differed between the two phases, particularly for the HRP. Both enzymes, as well as the substrates glucose and H2O2, partitioned to the citrate-rich phase; however, the Amplex Red substrate necessary to complete the sequential reaction partitioned strongly to the PEG-rich phase. Reactions in ATPS were quantitatively described by a mathematical model that incorporated measured partitioning and kinetic parameters. The model was then extended to new reaction conditions, i.e., higher enzyme concentration. Both experimental and computational results suggest mass transfer across the interface is vital to maintain the observed rate of product formation, which may be a means of metabolic regulation in vivo. Although outcomes for a specific system will depend on the particulars of the enzyme reactions and the microenvironments, this work demonstrates how coupled enzymatic reactions in complex, heterogeneous media can be understood in terms of a mathematical model.

Chemical Thermodynamics of Aqueous Atmospheric Aerosols: Modeling and Microfluidic Measurements

Science.gov (United States)

Nandy, L.; Dutcher, C. S.

2017-12-01

Accurate predictions of gas-liquid-solid equilibrium phase partitioning of atmospheric aerosols by thermodynamic modeling and measurements is critical for determining particle composition and internal structure at conditions relevant to the atmosphere. Organic acids that originate from biomass burning, and direct biogenic emission make up a significant fraction of the organic mass in atmospheric aerosol particles. In addition, inorganic compounds like ammonium sulfate and sea salt also exist in atmospheric aerosols, that results in a mixture of single, double or triple charged ions, and non-dissociated and partially dissociated organic acids. Statistical mechanics based on a multilayer adsorption isotherm model can be applied to these complex aqueous environments for predictions of thermodynamic properties. In this work, thermodynamic analytic predictive models are developed for multicomponent aqueous solutions (consisting of partially dissociating organic and inorganic acids, fully dissociating symmetric and asymmetric electrolytes, and neutral organic compounds) over the entire relative humidity range, that represent a significant advancement towards a fully predictive model. The model is also developed at varied temperatures for electrolytes and organic compounds the data for which are available at different temperatures. In addition to the modeling approach, water loss of multicomponent aerosol particles is measured by microfluidic experiments to parameterize and validate the model. In the experimental microfluidic measurements, atmospheric aerosol droplet chemical mimics (organic acids and secondary organic aerosol (SOA) samples) are generated in microfluidic channels and stored and imaged in passive traps until dehydration to study the influence of relative humidity and water loss on phase behavior.

Phase 2 of the International Piping Integrity Research Group programme

International Nuclear Information System (INIS)

Darlaston, B.J.

1994-01-01

The results of phase 1 of the International Piping Integrity Research Group (IPIRG-1) programme have been widely reported. The significance of the results is reviewed briefly, in order to put the phase 2 programme into perspective. The success of phase 1 led the participants to consider further development and validation of pipe and pipe component fracture analysis technology as part of another international group programme (IPIRG-2). The benefits of combined funding and of the technical exchanges and interactions are considered to be of significant advantage and value. The phase 2 programme has been designed with the overall objective of developing and experimentally validating methods of predicting the fracture behaviour of nuclear reactor safety-related piping, to both normal operating and accident loads. The programme will add to the engineering estimation analysis methods that have been developed for straight pipes. The pipe system tests will expand the database to include seismic loadings and flaws in fittings, such as bends, elbows and tees, as well as ''short'' cracks. The results will be used to validate further the analytical methods, expand the capability to make fittings and extend the quasi-static results for the USNRC's new programme on short cracks in piping and piping welds. The IPIRG-2 programme is described to provide a clear understanding of the content, strategy, potential benefits and likely significance of the work. ((orig.))

Cloud-point extraction of green-polymers from Cupriavidus necator lysate using thermoseparating-based aqueous two-phase extraction.

Science.gov (United States)

Leong, Yoong Kit; Lan, John Chi-Wei; Loh, Hwei-San; Ling, Tau Chuan; Ooi, Chien Wei; Show, Pau Loke

2017-03-01

Polyhydroxyalkanoates (PHAs), a class of renewable and biodegradable green polymers, have gained attraction as a potential substitute for the conventional plastics due to the increasing concern towards environmental pollution as well as the rapidly depleting petroleum reserve. Nevertheless, the high cost of downstream processing of PHA has been a bottleneck for the wide adoption of PHAs. Among the options of PHAs recovery techniques, aqueous two-phase extraction (ATPE) outshines the others by having the advantages of providing a mild environment for bioseparation, being green and non-toxic, the capability to handle a large operating volume and easily scaled-up. Utilizing unique properties of thermo-responsive polymer which has decreasing solubility in its aqueous solution as the temperature rises, cloud point extraction (CPE) is an ATPE technique that allows its phase-forming component to be recycled and reused. A thorough literature review has shown that this is the first time isolation and recovery of PHAs from Cupriavidus necator H16 via CPE was reported. The optimum condition for PHAs extraction (recovery yield of 94.8% and purification factor of 1.42 fold) was achieved under the conditions of 20 wt/wt % ethylene oxide-propylene oxide (EOPO) with molecular weight of 3900 g/mol and 10 mM of sodium chloride addition at thermoseparating temperature of 60°C with crude feedstock limit of 37.5 wt/wt %. Recycling and reutilization of EOPO 3900 can be done at least twice with satisfying yield and PF. CPE has been demonstrated as an effective technique for the extraction of PHAs from microbial crude culture. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Elementary steps and reaction pathways in the aqueous phase alkylation of phenol with ethanol

Energy Technology Data Exchange (ETDEWEB)

Eckstein, Sebastian; Hintermeier, Peter H.; Olarte, Mariefel V.; Liu, Yue; Baráth, Eszter; Lercher, Johannes A.

2017-08-01

The hydronium ion normalized reaction rate in aqueous phase alkylation of phenol with ethanol on H-MFI zeolites increases with decreasing concentration of acid sites. Higher rates are caused by higher concentrations of phenol in the zeolite pores, as the concentration of hydronium ions generated by zeolite Brønsted acid sites decreases. Considering the different concentrations of reacting species it is shown that the intrinsic rate constant for alkylation is independent of the concentration of hydronium ions in the zeolite pores. Alkylation at the aromatic ring of phenol and of toluene as well as O-alkylation of phenol have the same activation energy, 104 ± 5 kJ/mol. This is energetic barrier to form the ethyl carbenium ion from ethanol associated to the hydronium ion. Thus, in both the reaction pathways the catalyst involves a carbenium ion, which forms a bond to a nucleophilic oxygen (ether formation) or carbon (alkylation).

Hydrate phase equilibria of CO2+N2+aqueous solution of THF, TBAB or TBAF system

DEFF Research Database (Denmark)

Sfaxi, Imen Ben Attouche; Durand, Isabelle; Lugo, Rafael

2014-01-01

We report hydrate dissociation conditions of CO2 (15 and 30mol%)+N2 (85 and 70mol%) in the presence of aqueous solutions of THF, TBAB or TBAF. The concentrations of TBAB and TBAF in the aqueous solutions are 5wt% and 9wt% while THF concentration in aqueous solution is 3mol%. Two different experim...

Aqueous Stability of Alkali Superionic Conductors from First-Principles Calculations

International Nuclear Information System (INIS)

Radhakrishnan, Balachandran; Ong, Shyue Ping

2016-01-01

Ceramic alkali superionic conductor solid electrolytes (SICEs) play a prominent role in the development of rechargeable alkali-ion batteries, ranging from replacement of organic electrolytes to being used as separators in aqueous batteries. The aqueous stability of SICEs is an important property in determining their applicability in various roles. In this work, we analyze the aqueous stability of twelve well-known Li-ion and Na-ion SICEs using Pourbaix diagrams constructed from first-principles calculations. We also introduce a quantitative free-energy measure to compare the aqueous stability of SICEs under different environments. Our results show that though oxides are, in general, more stable in aqueous environments than sulfides and halide-containing chemistries, the cations present play a crucial role in determining whether solid phases are formed within the voltage and pH ranges of interest.

Electronic structure tautomerism, and mechanism of H-D exchange in imidazole aqueous solutions

International Nuclear Information System (INIS)

Borisov, Yu.A.; Vorob'eva, N.P.; Abronin, I.A.; Kolomiets, A.F.

1988-01-01

The imidazole electronic structure in a gaseous phase is studied taking into account the influence of solvation effects in aqueous solutions. Possible mechanisms of tautomeric transformations and H-D exchange reactions with water molecules are discussed. Using the quantum chemistry methods, it is shown that the intramolecular mechanism of imidazole isomerization in the gaseous phase and the aqueous solution is unprofitable, and the intermolecular mechanism can proceed through the stage of protonated and carbene form formation

Electromechanical phase transition of a dielectric elastomer tube under internal pressure of constant mass

Directory of Open Access Journals (Sweden)

Song Che

2017-05-01

Full Text Available The electromechanical phase transition for a dielectric elastomer (DE tube has been demonstrated in recent experiments, where it is found that the unbulged phase gradually changed into bulged phase. Previous theoretical works only studied the transition process under pressure control condition, which is not consistent with the real experimental condition. This paper focuses on more complex features of the electromechanical phase transition under internal pressure of constant mass. We derive the equilibrium equations and the condition for coexistent states for a DE tube under an internal pressure, a voltage through the thickness and an axial force. We find that under mass control condition the voltage needed to maintain the phase transition increases as the process proceeds. We analyze the entire process of electromechanical phase transition and find that the evolution of configurations is also different from that for pressure control condition.

Extraction mechanism of sulfamethoxazole in water samples using aqueous two-phase systems of poly(propylene glycol) and salt

Energy Technology Data Exchange (ETDEWEB)

Xie Xueqiao; Wang Yun; Han Juan [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yan Yongsheng, E-mail: yys@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

2011-02-14

Based on the poly(propylene glycol){sub 400} (PPG{sub 400})-salt aqueous two-phase system (ATPS), a green, economical and effective sample pretreatment technique coupled with high performance liquid chromatography was proposed for the separation and determination of sulfamethoxazole (SMX). The extraction yield of SMX in PPG{sub 400}-salt ATPS is influenced by various factors, including the salt species, the amount of salt, pH, and the temperature. Under the optimum conditions, most of SMX was partitioning into the polymer-rich phase with the average extraction efficiency of 99.2%, which may be attributed to the hydrophobic interaction and salting-out effect. This extraction technique has been successfully applied to the analysis of SMX in real water samples with the recoveries of 96.0-100.6%, the detection limits of 0.1 {mu}g L{sup -1}, and the linear ranges of 2.5-250.0 {mu}g L{sup -1}.

Containment and recovery of a light non-aqueous phase liquid plume at a woodtreating facility

International Nuclear Information System (INIS)

Crouse, D.; Powell, G.; Hawthorn, S.; Weinstock, S.

1997-01-01

A woodtreating site in Montana used a formulation (product) of 5 percent pentachlorophenol and 95 percent diesel fuel as a carrier liquid to pressure treat lumber. Through years of operations approximately 378,500 liters of this light non-aqueous phase liquid (LNAPL) product spilled onto the ground and soaked into the groundwater. A plume of this LNAPL product flowed in a northerly direction toward a stream located approximately 410 meters from the pressure treatment building. A 271-meter long high density polyethylene (HDPE) containment cutoff barrier wall was installed 15 meters from the stream to capture, contain, and prevent the product from migrating off site. This barrier was extended to a depth of 3.7 meters below ground surface and allowed the groundwater to flow beneath it. Ten product recovery wells, each with a dual-phase pumping system, were installed within the plume, and a groundwater model was completed to indicate how the plume would be contained by generating a cone of influence at each recovery well. The model indicated that the recovery wells and cutoff barrier wall would contain the plume and prevent further migration. To date, nearly 3 1/2 year's later, approximately 106,000 liters of product have been recovered

Investigation of the promoting effect of Mn on a Pt/C catalyst for the steam and aqueous phase reforming of glycerol

Energy Technology Data Exchange (ETDEWEB)

Bossola, Filippo; Pereira-Hernández, Xavier Isidro; Evangelisti, Claudio; Wang, Yong; Dal Santo, Vladimiro

2017-05-01

The catalytic performances in steam reforming (SR) and aqueous phase reforming (APR) of glycerol of a bimetallic Pt-Mn catalyst supported on activated carbon are investigated and correlated with the surface properties of the catalyst. Under SR conditions, Mn showed a significant promoting effect over Pt/C, both in terms of hydrogen production rate and conversion, with a higher selectivity toward the glycerol dehydration products. Upon addition of Mn the amount of strong Lewis acid sites increased, promoting the dehydration of glycerol and favoring the CAO over CAC cleavage at expenses of hydrogen selectivity. Conversely, under APR conditions, a slightly higher hydrogen selectivity and only minimal enhancement in hydrogen production were found, while the products selectivity was comparable to Pt/C. Most of Mn leached into the aqueous media, but the remaining (<5% of the fresh parent sample) might be alloyed with Pt and promote the CO desorption from neighbor Pt sites.

Aqueous-Phase Reactions of Isoprene with Sulfoxy Radical Anions as a way of Wet Aerosol Formation in the Atmosphere

Science.gov (United States)

Kuznietsova, I.; Rudzinski, K. J.; Szmigielski, R.; Laboratory of the Environmental Chemistry

2011-12-01

Atmospheric aerosols exhibit an important role in the environment. They have implications on human health and life, and - in the larger scale - on climate, the Earth's radiative balance and the cloud's formation. Organic matter makes up a significant fraction of atmospheric aerosols (~35% to ~90%) and may originate from direct emissions (primary organic aerosol, POA) or result from complex physico-chemical processes of volatile organic compounds (secondary organic aerosol, SOA). Isoprene (2-methyl-buta-1,3-diene) is one of the relevant volatile precursor of ambient SOA in the atmosphere. It is the most abundant non-methane hydrocarbon emitted to the atmosphere as a result of living vegetation. According to the recent data, the isoprene emission rate is estimated to be at the level of 500 TgC per year. While heterogeneous transformations of isoprene have been well documented, aqueous-phase reactions of this hydrocarbon with radical species that lead to the production of new class of wet SOA components such as polyols and their sulfate esters (organosulfates), are still poorly recognized. The chain reactions of isoprene with sulfoxy radical-anions (SRA) are one of the recently researched route leading to the formation of organosulfates in the aqueous phase. The letter radical species originate from the auto-oxidation of sulfur dioxide in the aqueous phase and are behind the phenomenon of atmospheric acid rain formation. This is a complicated chain reaction that is catalyzed by transition metal ions, such as manganese(II), iron(III) and propagated by sulfoxy radical anions . The presented work addresses the chemical interaction of isoprene with sulfoxy radical-anions in the water solution in the presence of nitrite ions and nitrous acid, which are important trace components of the atmosphere. We showed that nitrite ions and nitrous acid significantly altered the kinetics of the auto-oxidation of SO2 in the presence of isoprene at different solution acidity from 2 to 8

OZONATION BY-PRODUCTS 2. IMPROVEMENT OF AN AQUEOUS- PHASE DERIVITIZATION METHOD FOR THE DETECTION OF FORMALDEHYDE AND OTHER CARBONYL COMPOUNDS FORMED BY THE OZONATION OF DRINKING WATER

Science.gov (United States)

A method for the determination of low molecular weight aldehydes in water using aqueous-phase derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride has been improved by the use of high-resolution capillary GC. Detection limits with GC/ECD and GC/MS with ...

A simple reversed phase high-performance liquid chromatography (RP-HPLC method for determination of curcumin in aqueous humor of rabbit

Directory of Open Access Journals (Sweden)

Akhilesh Mishra

2014-01-01

Full Text Available This article describes a simple and rapid method for determination of curcumin (diferuloylmethane in aqueous humor of rabbit using high-performance liquid chromatography (HPLC. Analysis was performed using a C-18 column (250 × 4.6 mm, 5 μ luna by isocratic elution with a mobile phase containing 25 mM potassium dihydrogen orthophosphate (pH 3.5: Acetonitrile (40:60 and detection at 424 nm using a photodiode array (PDA detector for curcumin. The regression data for curcumin showed a good linear relationship with r 2 > 0.998 over the concentration range of 0.1-10 μg ml−1 . Relative standard deviations (RSD for the intraday and interday coefficient of variations for the assay were less than 5.0 and 8.5, respectively. The recovery of the method was between 79.8-83.6%. The quantification limit of the method for curcumin was 0.01 μg ml−1 . This method has good accuracy, precision, and quantitation limit. It is also concluded that the method is useful for measuring very low curcumin concentrations in aqueous humor.

Thermophysical Properties of Aqueous Solutions Used as Secondary Working Fluids

OpenAIRE

Melinder, Åke

2007-01-01

Secondary working fluids (secondary refrigerants, heat transfer fluids, antifreezes, brines) have long been used in various indirect re-frigeration and heat pump systems. Aqueous solutions (water solu-tions) have long been used as single phase (liquid only) secondary working fluids for cooling in supermarkets, ice rinks, heat recovery systems, heat pumps and other applications. However, aqueous solutions are increasingly used also for freezers in supermarkets and other applications in low tem...

Phase transitions and phase miscibility of mixed particles of ammonium sulfate, toluene-derived secondary organic material, and water.

Science.gov (United States)

Smith, Mackenzie L; You, Yuan; Kuwata, Mikinori; Bertram, Allan K; Martin, Scot T

2013-09-12

The phase states of atmospheric particles influence their roles in physicochemical processes related to air quality and climate. The phases of particles containing secondary organic materials (SOMs) are still uncertain, especially for SOMs produced from aromatic precursor gases. In this work, efflorescence and deliquescence phase transitions, as well as phase separation, in particles composed of toluene-derived SOM, ammonium sulfate, and water were studied by hygroscopic tandem differential mobility analysis (HTDMA) and optical microscopy. The SOM was produced in the Harvard Environmental Chamber by photo-oxidation of toluene at chamber relative humidities of toluene-derived SOM and aqueous ammonium sulfate, suggesting phase immiscibility between the two. Optical microscopy of particles prepared for ε = 0.12 confirmed phase separation for RH 0.5, the DRH values of ammonium sulfate in mixtures with SOM produced at toluene-derived SOM and aqueous ammonium sulfate across a limited range of organic volume fractions differentiates this SOM from previous reports for isoprene-derived SOM of full miscibility and for α-pinene-derived SOM of nearly full immiscibility with aqueous ammonium sulfate.

Isolation of plasma membranes from the nervous system by countercurrent distribution in aqueous polymer two-phase systems.

Science.gov (United States)

Schindler, Jens; Nothwang, Hans Gerd

2009-01-01

The plasma membrane separates the cell-interior from the cell's environment. To maintain homeostatic conditions and to enable transfer of information, the plasma membrane is equipped with a variety of different proteins such as transporters, channels, and receptors. The kind and number of plasma membrane proteins are a characteristic of each cell type. Owing to their location, plasma membrane proteins also represent a plethora of drug targets. Their importance has entailed many studies aiming at their proteomic identification and characterization. Therefore, protocols are required that enable their purification in high purity and quantity. Here, we report a protocol, based on aqueous polymer two-phase systems, which fulfils these demands. Furthermore, the protocol is time-saving and protects protein structure and function.

Temperature-induced phase separation and hydration in aqueous polymer solutions studied by NMR and IR spectroscopy: comparison of poly(N-vinylcaprolactam) and acrylamide-based polymers

Czech Academy of Sciences Publication Activity Database

Spěváček, Jiří; Dybal, Jiří

2014-01-01

Roč. 336, č. 1 (2014), s. 39-46 ISSN 1022-1360. [International IUPAC Conference on Polymer-Solvent Complexes and Intercalates /9./ - POLYSOLVAT-9. Kiev, 11.09.2012-14.09.2012] R&D Projects: GA ČR GA202/09/1281 Institutional support: RVO:61389013 Keywords : aqueous polymer solutions * FT-IR * NMR Subject RIV: CD - Macromolecular Chemistry

Synthesis of iron oxide nanoparticles under oxidizing environment and their stabilization in aqueous and non-aqueous media

International Nuclear Information System (INIS)

Maity, D.; Agrawal, D.C.

2007-01-01

Synthesis of magnetite (Fe 3 O 4 ) nanoparticles under oxidizing environment by precipitation from aqueous media is not straightforward because Fe 2+ gets oxidized to Fe 3+ and thus the ratio of Fe 3+ :Fe 2+ =2:1 is not maintained during the precipitation. A molar ratio of Fe 3+ :Fe 2+ smaller than 2:1 has been used by many to compensate for the oxidation of Fe 2+ during the preparation. In this work, we have prepared iron oxide nanoparticles in air environment by the precipitation technique using initial molar ratios Fe 3+ :Fe 2+ ≤2:1. The phases of the resulting powders have been determined by several techniques. It is found that the particles consist mainly of maghemite with little or no magnetite phase. The particles have been suspended in non-aqueous and aqueous media by coating the particles with a single layer and a bilayer of oleic acid, respectively. The particle sizes, morphology and the magnetic properties of the particles and the ferrofulids prepared from these particles are reported. The average particle sizes obtained from the TEM micrographs are 14, 10 and 9 nm for the water, kerosene and dodecane-based ferrofluids, respectively, indicating a better dispersion in the non-aqueous media. The specific saturation magnetization (σ s ) value of the oleic-acid-coated particles (∼53 emu/g) is found to be lower than that for the uncoated particles (∼63 emu/g). Magnetization σ s of the dodecane-based ferrofluid is found to be 10.1 emu/g for a volume fraction of particles φ=0.019. Zero coercivity and zero remanance on the magnetization curves indicate that the particles are superparamagnetic (SPM) in nature

Infiltration characteristics of non-aqueous phase liquids in undisturbed loessal soil cores

Institute of Scientific and Technical Information of China (English)

WANG Yunqiang; SHAO Ming'an

2009-01-01

The widespread contamination of soils and aquifers by non-aqueous phase liquids (NAPL), such as crude oil, poses serious environmental and health hazards globally. Understanding the infiltration characteristics of NAPL in soil is crucial in mitigating or remediating soil contamination. The infiltration characteristics of crude and diesel oils into undisturbed loessal soil cores, collected in polymethyl methacrylate cylindrical columns, were investigated under a constant fluid head (3 cm) of either crude oil or diesel oil. The infiltration rate of both crude and diesel oils decreased exponentially as wetting depth increased with time. Soil core size and bulk density both had a significant effect on NAPL infiltration through the undisturbed soil cores; a smaller core size or a greater bulk density both reduced oil penetration to depth. Compacting soil in areas susceptible to oil spills may be an effective way to reduce contamination. The infiltration of NAPL into soil cores was spatially anisotropic and heterogeneous, thus recording the data at four points on the soil core is a good way to improve the accuracy of experimental results. Our results provided information about crude and diesel oils, rather than their components, and may have practical value for remediation of contaminated loessal soils.

Predictive Modelling of Phase-Transfer Catalyst Systems for Improved and Innovative Design

DEFF Research Database (Denmark)

Anantpinijwatna, Amata; Hyung Kim, Sun; Sales-Cruz, Mauricio

2016-01-01

Phase-transfer catalyst (PTC) systems contain two immiscible liquid phases with a heterogeneous PTC transferring active ion from one phase to the other for converting the reactant to the desired product, and in the process generating the inactive ion. This type of reacting systems is receiving...... increasing attention as a novel organic synthesis option due to its flexible and easier operation, higher production yield, and ability to eliminate expensive solvents, although, not eliminating the use of solvents. New mathematical models of the PTC system, which includes physical and chemical equilibrium......, reaction mechanism and unit operation has been developed. In the developed model, the PTC system is divided into four sub-systems of aqueous-organic solvent partition, inorganic salt in aqueous phase, PTC in aqueous phase, and PTC in aqueous phase. Each subsystem requires an appropriate thermodynamic model...

The buffering-out effect and phase separation in aqueous solutions of EPPS buffer with 1-propanol, 2-propanol, or 2-methyl-2-propanol at T = 298.15 K

International Nuclear Information System (INIS)

Taha, Mohamed; Teng, Han-Lan; Lee, Ming-Jer

2012-01-01

Highlights: ► Buffering-out is a new liquid–liquid phase separation containing biological buffer. ► EPPS buffer-induced phase separation of aqueous solutions of aliphatic alcohols. ► Phase diagrams of EPPS + water + 1-propanol/2-propanol/2-methyl-2-propanol are studied. ► EPPS breaks the 1-propanol + water and 2-methyl-2-propanol + water azeotropes. ► The (liquid + liquid) equilibria can be well correlated by the NRTL model. - Abstract: Buffering-out is a new liquid–liquid phase separation phenomenon observed in mixtures containing a buffer as a mass separating agent. The (liquid + liquid) equilibrium (LLE) and (solid + liquid + liquid) equilibrium (SLLE) data were measured for the ternary systems {3-[4-(2-hydroxyethyl)piperazin-1-yl]propanesulfonic acid (EPPS) buffer + 1-propanol, 2-propanol, or 2-methyl-2-propanol + water} at T = 298.15 K under atmospheric pressure. The phase boundary data were fitted to an empirical equation relating to the concentrations of organic solvent and buffer. The effective excluded volume (EEV) values of EPPS were obtained from the phase boundary data. The phase-separation abilities of the investigated aliphatic alcohols were discussed. The reliability of the experimental tie-lines was satisfactorily confirmed by the Othmer–Tobias correlation. The experimental tie-lines data for the ternary systems have been correlated using the NRTL activity coefficient model. The separation of these aliphatic alcohols from their azeotropic aqueous mixtures is of particular interest to industrial process. The addition of the EPPS as an auxiliary agent breaks the (1-propanol + water) and (2-methyl-2-propanol + water) azeotropes. The possibility of using the new phase separation systems in the extraction process is demonstrated by using different dyestuffs.

Partition of proteins in aqueous two-phase systems based on Cashew-nut tree gum and poly(ethylene glycol

Directory of Open Access Journals (Sweden)

Leonie Asfora Sarubbo

2004-09-01

Full Text Available The partitioning of two proteins, bovine serum albumin (BSA and trypsin was studied in an aqueous poly(ethylene glycol(PEG- Cashew-nut tree gum system. The phase diagram was provided for Cashew-nut tree gum and PEG molecular weight of 1500 at two different temperatures. The influence of several parameters including concentrations of polymers, pH, salt addition and temperature on the partitioning of these proteins were investigated.. The results of this research demonstrated the importance of the protein characteristics for partitioning in aqueous biphasic system.A partição de duas proteínas, albumina de soro bovino (BSA e tripsina foi estudada no sistema bifásico aquoso Polietileno glicol(PEG - Goma do cajueiro. O diagrama de fases foi estabelecido para a Goma do Cajueiro e para PEG de peso molecular 1500 em duas diferentes temperaturas. A influência de vários parâmetros na partição destas proteínas, incluindo concentração dos polímeros, pH, adição de sal e temperatura foi investigada. Os resultados desta pesquisa demonstraram a importância das características da proteína na partição em sistemas bifásicos aquosos.

Extraction of Biomolecules Using Phosphonium-Based Ionic Liquids + K3PO4 Aqueous Biphasic Systems

Science.gov (United States)

Louros, Cláudia L. S.; Cláudio, Ana Filipa M.; Neves, Catarina M. S. S.; Freire, Mara G.; Marrucho, Isabel M.; Pauly, Jérôme; Coutinho, João A. P.

2010-01-01

Aqueous biphasic systems (ABS) provide an alternative and efficient approach for the extraction, recovery and purification of biomolecules through their partitioning between two liquid aqueous phases. In this work, the ability of hydrophilic phosphonium-based ionic liquids (ILs) to form ABS with aqueous K3PO4 solutions was evaluated for the first time. Ternary phase diagrams, and respective tie-lines and tie-lines length, formed by distinct phosphonium-based ILs, water, and K3PO4 at 298 K, were measured and are reported. The studied phosphonium-based ILs have shown to be more effective in promoting ABS compared to the imidazolium-based counterparts with similar anions. Moreover, the extractive capability of such systems was assessed for distinct biomolecules (including amino acids, food colourants and alkaloids). Densities and viscosities of both aqueous phases, at the mass fraction compositions used for the biomolecules extraction, were also determined. The evaluated IL-based ABS have been shown to be prospective extraction media, particularly for hydrophobic biomolecules, with several advantages over conventional polymer-inorganic salt ABS. PMID:20480041

Retention of ionisable compounds on high-performance liquid chromatography XVI. Estimation of retention with acetonitrile/water mobile phases from aqueous buffer pH and analyte pKa.

Science.gov (United States)

Subirats, Xavier; Bosch, Elisabeth; Rosés, Martí

2006-07-21

In agreement with our previous studies and those of other authors, it is shown that much better fits of retention time as a function of pH are obtained for acid-base analytes when pH is measured in the mobile phase, than when pH is measured in the aqueous buffer when buffers of different nature are used. However, in some instances it may be more practical to measure the pH in the aqueous buffer before addition of the organic modifier. Thus, an open methodology is presented that allows prediction of chromatographic retention of acid-base analytes from the pH measured in the aqueous buffer. The model presented estimates the pH of the buffer and the pKa of the analyte in a particular acetonitrile/water mobile phase from the pH and pKa values in water. The retention of the analyte can be easily estimated, at a buffer pH close to the solute pKa, from these values and from the retentions of the pure acidic and basic forms of the analyte. Since in many instances, the analyte pKa values in water are not known, the methodology has been also tested by using Internet software, at reach of many chemists, which calculates analyte pKa values from chemical structure. The approach is successfully tested for some pharmaceutical drugs.

A portable and autonomous multichannel fluorescence detector for on-line and in situ explosive detection in aqueous phase.

Science.gov (United States)

Xin, Yunhong; Wang, Qi; Liu, Taihong; Wang, Lingling; Li, Jia; Fang, Yu

2012-11-21

A multichannel fluorescence detector used to detect nitroaromatic explosives in aqueous phase has been developed, which is composed of a five-channel sample-sensor unit, a measurement and control unit, a microcontroller, and a communication unit. The characteristics of the detector as developed are mainly embedded in the sensor unit, and each sensor consists of a fluorescent sensing film, a light emitting diode (LED), a multi-pixel photon counter (MPPC), and an optical module with special bandpass optical filters. Due to the high sensitivity of the sensing film, the small size and low cost of LED and MPPC, the developed detector not only has a better detecting performance and small size, but also has a very low cost - it is an alternative to the device made with an expensive high power lamp and photomultiplier tube. The wavelengths of the five sensors covered extend from the upper UV through the visible spectrum, 370-640 nm, and thereby it possesses the potential to detect a variety of explosives and other hazardous materials in aqueous phase. An additional function of the detector is its ability to function via a wireless network, by which the data recorded by the detector can be sent to the host computer, and at the same time the instructions can be sent to the detector from the host computer. By means of the powerful computing ability of the host computer, and utilizing the classical principal component analysis (PCA) algorithm, effective classification of the analytes is achieved. Furthermore, the detector has been tested and evaluated using NB, PA, TNT and DNT as the analytes, and toluene, benzene, methanol and ethanol as interferent compounds (concentration various from 10 and 60 μM). It has been shown that the detector can detect the four nitroaromatics with high sensitivity and selectivity.

Formation of U(IV) Nanoparticles and Their Growth Mechanism in Mildly Acidic Aqueous Phases

Energy Technology Data Exchange (ETDEWEB)

Cha, Wan Sik; Kim, Sun Tae; Cho, Hye Ryun; Jung, Euo Chang [KAERI, Daejeon (Korea, Republic of)

2016-05-15

Previous studies suggest that U(IV) nanoparticle (NP) formation is one of key steps in mineralization or immobilization of uranium which can be mediated either by microbes or by abiotic geochemical reactions. Colloidal NPs in a groundwater system are potential carrier phases influencing RN migration in subsurface environment. However, the mechanism of U(IV) NP formation and the potential reaction intermediates during this solid phase formation process have not been elucidated in detail so far. In this study we attempted to examine the U(IV) nanoparticle formation reactions preceded by the hydrolysis of U{sup 4+} at different pHs, concentrations and temperatures. The kinetics of U(IV) NP formation from dissolved U(IV) species was monitored under mildly acidic conditions (pH 2 ∼ 3) mainly by using UV-Vis absorption spectrophotometry. Dynamic light scattering (DLS) analysis, nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM) were used to characterize the NPs produced during the reactions. The results demonstrate that the U(IV) NP formation process is very sensitive toward temperature variation. The main outcome of this study is the discovery of the autocatalytic nature of U(IV) NP formation from the supersaturated U(OH){sup 3+} solution in a mildly acidic aqueous solution. The structure of reaction intermediates is proposed to contain oxide linkage. In the presentation the proposed mechanism of the U(IV) NP formation reaction and the properties of primary NPs and their clusters will be discussed in detail.

An accurate cost effective DFT approach to study the sensing behaviour of polypyrrole towards nitrate ions in gas and aqueous phases.

Science.gov (United States)

Wasim, Fatima; Mahmood, Tariq; Ayub, Khurshid

2016-07-28

Density functional theory (DFT) calculations have been performed to study the response of polypyrrole towards nitrate ions in gas and aqueous phases. First, an accurate estimate of interaction energies is obtained by methods calibrated against the gold standard CCSD(T) method. Then, a number of low cost DFT methods are also evaluated for their ability to accurately estimate the binding energies of polymer-nitrate complexes. The low cost methods evaluated here include dispersion corrected potential (DCP), Grimme's D3 correction, counterpoise correction of the B3LYP method, and Minnesota functionals (M05-2X). The interaction energies calculated using the counterpoise (CP) correction and DCP methods at the B3LYP level are in better agreement with the interaction energies calculated using the calibrated methods. The interaction energies of an infinite polymer (polypyrrole) with nitrate ions are calculated by a variety of low cost methods in order to find the associated errors. The electronic and spectroscopic properties of polypyrrole oligomers nPy (where n = 1-9) and nPy-NO3(-) complexes are calculated, and then extrapolated for an infinite polymer through a second degree polynomial fit. Charge analysis, frontier molecular orbital (FMO) analysis and density of state studies also reveal the sensing ability of polypyrrole towards nitrate ions. Interaction energies, charge analysis and density of states analyses illustrate that the response of polypyrrole towards nitrate ions is considerably reduced in the aqueous medium (compared to the gas phase).

Matrix supported tailored polymer for solid phase extraction of fluoride from variety of aqueous streams

International Nuclear Information System (INIS)

Thakur, Neha; Kumar, Sanjukta A.; Wagh, D.N.; Das, Sadananda; Pandey, Ashok K.; Kumar, Sangita D.; Reddy, A.V.R.

2012-01-01

Highlights: ► Th complexed with poly (bis[2-(methacryloyloxy)-ethyl]phosphate) as tailored polymer membranes. ► Membranes offered high capacity and selectivity for fluoride in aqueous media. ► Quantitative uptake (80 ± 5%) of fluoride. ► Fast sorption kinetics. ► Reusability of polymer membranes. - Abstract: Fluoride related health hazards (fluorosis) are a major environmental problem in many regions of the world. It affects teeth; skeleton and its accumulation over a long period can lead to changes in the DNA structure. It is thus absolutely essential to bring down the fluoride levels to acceptable limits. Here, we present a new inorganic–organic hybrid polymer sorbent having tailored fixed-sites for fluoride sorption. The matrix supported poly (bis[2-(methacryloyloxy)-ethyl]phosphate) was prepared by photo-initiator induced graft-polymerization in fibrous and microporous (sheet) host poly(propylene) substrates. These substrates were conditioned for selective fluoride sorption by forming thorium complex with phosphate groups on bis[2-methacryloyloxy)-ethyl] phosphate (MEP). These tailored sorbents were studied for their selectivity towards fluoride in aqueous media having different chemical conditions. The fibrous sorbent was found to take up fluoride with a faster rate (15 min for ≈76% sorption) than the sheet sorbent. But, the fluoride loading capacity of sheet sorbent (4320 mg kg −1 ), was higher than fibrous and any other sorbent reported in the literature so far. The sorbent developed in the present work was found to be reusable after desorption of fluoride using NaOH solution. It was tested for solid phase extraction of fluoride from natural water samples.

Poly High Internal Phase Emulsion for the Immobilization of Chemical Warfare Agents.

Science.gov (United States)

Wright, Alexander J; Main, Marcus J; Cooper, Nicholas J; Blight, Barry A; Holder, Simon J

2017-09-20

We report a facile method for the absorption (characterized by the weight/weight swelling degree, Q) of a variety of chemical warfare agents (CWAs); including sulfur mustard (HD) (Q = 40) and V-series (VM, VX, i-Bu-VX, n-Bu-VX) of nerve agents (Q ≥ 45) and a simulant, methyl benzoate (Q = 55), through the use of a poly(styrene-co-vinyl benzyl chloride-co-divinylbenzene) lightly cross-linked poly high internal phase emulsion (polyHIPE). By varying the vinyl benzyl chloride (VBC) content and the volume of the internal phase of the precursor emulsion it is demonstrated that absorption is facilitated both by the swelling of the polymer and the uptake of liquid in the pores. In particular the sample prepared from a 95% internal emulsion water content showed rapid swelling (<5 min to total absorption) and the ability to swell both from a monolithic state and from a compressed state, making these systems ideal practical candidates for the rapid immobilization of CWAs.

High-yield acetonitrile | water triple phase boundary electrolysis at platinised Teflon electrodes

Energy Technology Data Exchange (ETDEWEB)

Watkins, John D.; MacDonald, Stuart M.; Fordred, Paul S.; Bull, Steven D. [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Gu, Yunfeng; Yunus, Kamran; Fisher, Adrian C. [Department of Chemical Engineering, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA (United Kingdom); Bulman-Page, Philip C. [School of Chemistry, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom); Marken, Frank [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom)], E-mail: f.marken@bath.ac.uk

2009-11-30

A dynamic acetonitrile | aqueous electrolyte phase boundary in contact with platinised Teflon working electrodes is investigated. High concentrations of salt in the aqueous phase (2 M NaCl and 0.1 M NaClO{sub 4}) ensure immiscibility and the polar nature of acetonitrile aids the formation of a well-behaved triple phase boundary reaction zone. The one-electron oxidation of tert-butylferrocene in the organic phase without intentionally added electrolyte is studied. The limiting current for the flowing triple phase boundary process is shown to be essentially volume flow rate independent. The process is accompanied by the transfer of perchlorate from the aqueous into the organic phase and the flux of anions is shown to be approximately constant along the dynamic acetonitrile | aqueous electrolyte | platinum line interface. A high rate of conversion (close to 100%) is achieved at slow volume flow rates and at longer platinum electrodes.

Aqueous Nucleation and Growth of Titanium Oxides Using Time-Resolved Synchrotron X- ray Diffraction

Science.gov (United States)

Hummer, D. R.; Heaney, P. J.; Post, J. E.

2006-05-01

The inorganic precipitation of oxide minerals in soil environments has profound effects on a variety of geochemical processes. These include the removal of metals from the aqueous phase, the production of coatings that reduce the reactive surface area of pre-existing mineral grains, and the generation of feedstocks for microbial metabolic reactions. Recent observations of transient, metastable phases during the growth of oxide crystallites has raised questions about their role in crystallization mechanisms, and created a need for more detailed structural measurements. To better understand the process of nucleation and growth, we investigated the crystallization of Ti oxides from aqueous 0.5 M TiCl4 solutions using synchrotron X-ray diffraction at temperatures of 100 and 150 °C. Solutions were heated in a 1.0 mm internal diameter quartz glass capillary sealed with epoxy. Powder diffraction patterns of the growing crystallites were collected using image plate technology with a time step of ~ 4 minutes, providing high resolution in situ measurements of structural changes during the crystallization process. The data indicate a co-precipitation of the two crystalline phases anatase and rutile within the first 30 minutes of heating, followed by a gradual phase transition from anatase to rutile during particle coarsening throughout the 10 hour duration of an experiment. The co-existence of anatase and rutile at the onset of crystallization lends additional support to the assertion of nearly identical free energies for anatase and rutile at the nanoscale, believed to be due to the prominence of surface energy effects (Ranade et al., 2001). Whole pattern analyses using the Rietveld refinement method also documented previously unobserved changes in lattice parameters of both phases during growth, on the order of 0.2-0.3 % expansion for each axis. The trends in lattice parameters are observed to be temperature dependent, generally having lower values at higher

Experimental and numerical investigations of ionic liquid-aqueous flow in microchannel

Science.gov (United States)

Li, Qi; Tsaoulidis, Dimitrios; Angeli, Panagiota

2015-11-01

The hydrodynamic characteristics of plug flow of an ionic liquid-aqueous two-phase system in a microchannel were studied experimentally and numerically. A mixture of 0.2M N-octyl(plenyl)-N,N-diisobutylcarbamoylmethyphosphine oxide (CMOP)- 1.2 M Tri-n-butylphosphate (TBP) in room temperature ionic liquid 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide ([C4min][NTf2]), and a nitric acid solution of 1M were chosen. These fluids are relevant Eu(III) separation by extraction from nitric acid solutions. The two liquid phases were introduced into microchannels of 0.2 and 0.5mm internal diameter through a T-junction inlet. The flow pattern was visualized during plug formation at the inlet section and further downstream by means by bright field planar micro-Particle Image Velocimetry. Key features of plug flow, such as plug velocity, film thickness, plug length and recirculation intensity were measured under various experimental conditions. To gain further understanding of the 3-D flow field, Computation Fluid Dynamics (CFD) simulations approach were also conducted.

Study on frictional pressure drop of steam-water two phase flow in optimized four-head internal-ribbed tube

International Nuclear Information System (INIS)

Wang Weishu; Zhu Xiaojing; Bi Qincheng; Wu Gang; Yu Shuiqing

2012-01-01

The optimized internal-ribbed tube is different from the normal internal-ribbed tube on the frictional pressure drop characteristics. The frictional pressure drop characteristics of steam-water two phase flow in horizontal four-head optimized internal-ribbed were studied under adiabatic condition. According to the experimental and calculation results, the two-phase multiplier is greatly affected by the steam quality and pressure. The two-phase multiplier increases with increasing quality, and decreases with increasing pressure. In the near-critical pressure region, the two-phase multiplier is close to 1. The frictional pressure drop of two phase flow in optimized tube is less than that in the normal tube under the same work condition. The good hydrodynamic condition could be achieved when the optimized internal-ribbed tube is used in the heat transfer equipment because the self-compensating characteristics exist due to the reduction of frictional pressure drop. (authors)

Effect of pH to adsorption behavior of Pu on bentonite in aqueous environment

International Nuclear Information System (INIS)

Wang Xiaoqiang; Tuo Xianguo; Li Pingchuan; Leng Yangchun; Su Jilong; Yueping

2013-01-01

The effects of pH to the adsorption behavior of Pu in GMZ-bentonite, Lingshou Ca-bentonite, Na-bentonite and bleaching earth were tested by static adsorption experiments in aqueous environment. The results show that the adsorption equilibrium time of Pu is four days in GMZ-bentonite and 5-6 days in bleaching earth, Ca-bentonite and Na-bentonite. In aqueous environment, the adsorption capacity of bentonite to Pu increases with pH in water phase, and it is weak in acidic aqueous environment and strong in alkaline aqueous environment extremely. (authors)

Solubility and phase separation of 4-morpholinepropanesulfonic acid (MOPS), and 3-morpholino-2-hydroxypropanesulfonic acid (MOPSO) in aqueous 1,4-dioxane and ethanol solutions

International Nuclear Information System (INIS)

Taha, Mohamed; Lee, Ming-Jer

2011-01-01

Highlights: → Solubilities of MOPS and MOPSO buffers in aqueous 1,4-dioxane and ethanol solutions. → We found that MOPS-induced phase separation of aqueous solution of 1,4-dioxane. → The phase diagram of (MOPS + water + 1,4-dioxane) system at 298.15 K is documented. → The tie-lines within the two-liquid phase region were also determined at 298.15 K. → The effective excluded volume theory was applied to correlate the binodal LLE data. - Abstract: The buffers 4-morpholinepropanesulfonic acid (MOPS) and 3-morpholino-2-hydroxypropanesulfonic acid (MOPSO) are useful biological zwitterionic buffers within the pH range of 6.5 to 7.9 and 6.2 to 7.6, respectively. The solubilities of these buffers were determined in binary mixtures (1,4-dioxane + water) and (ethanol + water) at T = 298.15 K by using the results of density measurements. It has been observed that MOPS induced liquid-liquid phase splitting for the mixtures of 40% to 90% (w/w) 1,4-dioxane in water. The two-liquid phase formation was visualized with disperse orange 25. The phase equilibrium boundaries, including the regions of one liquid, two liquids, (one liquid + one solid) and (two liquids + one solid), for the (MOPS + water + 1,4-dioxane) system have been determined experimentally at T = 298.15 K. The tie lines of the (liquid + liquid) equilibrium were also measured. The Othmer-Tobias and Bancroft equation were used to evaluate the reliability of the tie-line data. The binodal curve was fitted to an empirical equation and the effective excluded volume (EEV) model. The apparent free energies of transfer (ΔG tr ' ) of MOPS and MOPSO from water to 1,4-dioxane and ethanol solutions have been calculated from the solubility data. These ΔG tr ' values were compared with those of some related biological buffers (TRIS, TAPS, TAPSO, and TABS). Furthermore, we also calculated the contribution of transfer free energies (Δg tr ' ) of -OH group from water to 1,4-dioxane and ethanol solutions.

Dysprosium separation from aqueous phase by non-dispersive solvent extraction employing hollow fibre membrane module

International Nuclear Information System (INIS)

Yadav, Kartikey K.; Singh, D.K.; Kain, V.

2017-01-01

Rare earth elements (REEs) consist of fourteen lanthanides and three elements which are Sc, Y and La resulting in total 17 REEs. In the last decade, these rare earths elements which have unique physical and chemical properties have been highly in demand for their application in almost all walks of life. Various methods such as ion exchange, precipitation and solvent extraction have been used to recover these elements from aqueous solutions. These traditional methods have some inherent disadvantages like handling of hazardous organic chemicals, ineffectiveness to recover a very low concentration of contaminated source etc. In this regard, an important method i.e. liquid membrane offers separation scheme; which combines the characteristics, of solvent extraction and solid membrane separation, to overcome the disadvantages of conventional techniques. Various experiments were carried out to evaluate the effect of feed acidity, metal ion concentration, carrier concentration, feed composition, flow rates and phase ratio on the transport of rare earths metal ions across the membrane

A green deep eutectic solvent-based aqueous two-phase system for protein extracting.

Science.gov (United States)

Xu, Kaijia; Wang, Yuzhi; Huang, Yanhua; Li, Na; Wen, Qian

2015-03-15

As a new type of green solvent, deep eutectic solvent (DES) has been applied for the extraction of proteins with an aqueous two-phase system (ATPS) in this work. Four kinds of choline chloride (ChCl)-based DESs were synthesized to extract bovine serum albumin (BSA), and ChCl-glycerol was selected as the suitable extraction solvent. Single factor experiments have been done to investigate the effects of the extraction process, including the amount of DES, the concentration of salt, the mass of protein, the shaking time, the temperature and PH value. Experimental results show 98.16% of the BSA could be extracted into the DES-rich phase in a single-step extraction under the optimized conditions. A high extraction efficiency of 94.36% was achieved, while the conditions were applied to the extraction of trypsin (Try). Precision, repeatability and stability experiments were studied and the relative standard deviations (RSD) of the extraction efficiency were 0.4246% (n=3), 1.6057% (n=3) and 1.6132% (n=3), respectively. Conformation of BSA was not changed during the extraction process according to the investigation of UV-vis spectra, FT-IR spectra and CD spectra of BSA. The conductivity, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to explore the mechanism of the extraction. It turned out that the formation of DES-protein aggregates play a significant role in the separation process. All the results suggest that ChCl-based DES-ATPS are supposed to have the potential to provide new possibilities in the separation of proteins. Copyright © 2015 Elsevier B.V. All rights reserved.

One-pot aqueous phase catalytic conversion of sorbitol to gasoline over nickel catalyst

International Nuclear Information System (INIS)

Weng, Yujing; Qiu, Songbai; Xu, Ying; Ding, Mingyue; Chen, Lungang; Zhang, Qi; Ma, Longlong; Wang, Tiejun

2015-01-01

Highlights: • Directly production gasoline (C5–C12 alkanes) from biomass-derived sugar alcohol sorbitol. • Temperature of STG (553–593 K) was lower than that of traditional methanol to gasoline (MTG) (623–773 K). • Gasoline yield of 46.9% and C7–C12 hydrocarbons reached up to 45.5% in the gasoline products. - Abstract: The carbon chain extension and hydrodeoxygenation steps play critical roles in the high-energy-density hydrocarbons production. In this paper, a systematic study had been carried out to investigate one-pot aqueous phase catalytic conversion of sorbitol to gasoline (STG) over bifunctional Ni-based catalysts. Characterization technologies of N 2 physisorption, X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and NH 3 temperature-programmed desorption (NH 3 -TPD) were used to study the textural properties, phase compositions, acid behavior and morphologies of the catalysts. The catalytic performances were tested in a fixed bed reactor. It was found that the physically mixed Ni/HZSM-5 and Ni/silica-gel (mesoporous SG) catalyst realized the carbon chain extension and exhibited excellent performances on hydrodeoxygenation (HDO) reaction (46.9% of gasoline (C5–C12) yield and 45.5% of C7–C12 hydrocarbons in the gasoline products). Especially, the temperature of STG (553–593 K) was lower obviously than that of the traditional methanol to gasoline (MTG) process (623–773 K). It provided a novel transformation of sorbitol to long-chain alkanes by one-pot process over the bifunctional catalyst (Ni@HZSM-5/SG), wherein hydrodeoxygenation, ketonization and aldol condensation steps were integrated

Water-dispersable hybrid Au-Pd nanoparticles as catalysts in ethanol oxidation, aqueous phase Suzuki-Miyaura and Heck reactions

KAUST Repository

Song, Hyon Min

2012-01-01

The catalytic activities of water-dispersable Au@Pd core-shell nanoparticles (NPs) and Au-Pd alloy NPs were examined. There is growing interest in Au-Pd hybridized NPs in a supported matrix or non-supported forms as catalysts in various reactions that are not limited to conventional Pd-related reactions. Four different Au@Pd core-shell NPs in this study were prepared at room temperature with help from the emulsion phase surrounding the Au core NPs. Au-Pd alloy NPs were prepared over 90 °C, and underwent phase transfer to aqueous medium for their catalytic use. Au@Pd core-shell NPs show catalytic activity in ethanol oxidation reactions as electrocatalysts, and both core-shell and alloy NPs are good to excellent catalysts in various Suzuki-Miyaura and Heck reactions as heterogeneous catalysts. Specifically, Au@Pd core-shell NPs with sharp branched arms show the highest yield in the reactions tested in this study. A relatively small amount (0.25 mol%) was used throughout the catalytic reactions. © 2012 The Royal Society of Chemistry.

Extraction of hafnium with chelating agents from aqueous-alcoholic solutions

International Nuclear Information System (INIS)

Hala, J.; Prihoda, J.

1975-01-01

The extraction was studied of hafnium into solutions of N-benzoyl-N-phenylhydroxylamine, 2-thenoyltrifluoroacetone and di-n-butylphosphoric acid in benzene, toluene, chloroform and tetrachloromethane from aqueous alcoholic solutions with a formal acidity of 2M-HClO 4 . Methyl-, ethyl-, n- and isopropyl- and tert-butyl alcohol were used as organic components in the mixed aqueous-organic phase. In the extraction into N-benzoyl-N-phenylhydroxylamine the presence of the alcohols resulted in synergic effects analogous to the previously described extraction by substituted benzoylpyrazolone. With the other two extractants, the effect of the alcohols was antagonistic, due to the interaction of alcohol or water with the reagent in the organic phase, and to the decrease in the reagent distribution constant. (author)

Mercury absorption in aqueous hypochlorite

International Nuclear Information System (INIS)

Zhao, L.L.; Rochelle, G.T.

1999-01-01

The absorption of elemental Hg vapor into aqueous hypochlorite was measured in a stirred tank reactor at 25 and 55C. NaOCl strongly absorbs Hg even at high pH. Low pH, high Cl - and high-temperature favor mercury absorption. Aqueous free Cl 2 was the active species that reacted with mercury. However, chlorine desorption was evident at high Cl - and pH 15 M -1 s -1 at 25C and 1.4x10 17 M -1 s -1 at 55C. Gas-phase reaction was observed between Hg and Cl 2 on apparatus surfaces. Strong mercury absorption in water was also detected with Cl 2 present. Results indicate that the chlorine concentration, moisture, and surface area contribute positively to mercury removal. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Phase evolution and aqueous durability of Zr{sub 1−x−y}Ce{sub x}Nd{sub y}O{sub 2−y/2} ceramics designed to immobilize actinides with multi-valences

Energy Technology Data Exchange (ETDEWEB)

Ding, Yi, E-mail: dingyi2279@126.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Key Subject Laboratory of National Defense for Radioactive Waste and Environmental Security, Southwest University of Science and Technology, Mianyang 621010 (China); Long, Xinggui, E-mail: xingguil@caep.cn [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Peng, Shuming [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Zhang, Dong, E-mail: zd0823@sina.com [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Tan, Zhaoyi [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, Sichuan, 621900 (China); Lu, Xirui [Key Subject Laboratory of National Defense for Radioactive Waste and Environmental Security, Southwest University of Science and Technology, Mianyang 621010 (China)

2017-04-15

Zr{sub 1−x−y}Ce{sub x}Nd{sub y}O{sub 2−y/2} ceramics, which were designed as waste form materials, were obtained by simultaneous substitution of Ce{sup 4+} and Nd{sup 3+} for Zr{sup 4+} in ZrO{sub 2}. The influences of the simultaneous substitution of Ce and Nd on phase transformation of ZrO{sub 2} were investigated systematically. Also, the aqueous durability of the ceramics was evaluated. The results show that the phase transformation caused by the simultaneous substitution mainly relates to the total content of Ce and Nd. The ZrO{sub 2} ceramics containing Ce + Nd < 30 mol% exhibit both monoclinic and cubic phases, while the ceramics containing Ce + Nd ≥ 30 mol% are cubic phase. And the cubic phase can be stabilized by incorporating 30 mol% Ce + Nd. Moreover, LR{sub i} are modified by the incorporation of Ce and Nd, because of the presence of oxygen vacancies. The Nd and Ce co-doped zirconia waste form exhibit excellent aqueous durability (∼10{sup −5} g m{sup −2} d{sup −1}). - Highlights: •Zr{sub 1−x−y}Ce{sub x}Nd{sub y}O{sub 2−y/2} were obtained by substitution of Ce and Nd for Zr in ZrO{sub 2}. •Phase transformation mainly relates to the total content of Ce and Nd. •Samples with Ce + Nd < 30 mol% show monoclinic and cubic phases, while ≥30 mol% are cubic. •Stabilized cubic zirconia can be obtained by doping with 30 mol% Ce and Nd. •LR{sub Ce} and LR{sub Nd} (42 d) are ∼ 10{sup −5} g m{sup −2} d{sup −1}, exhibiting excellent aqueous durability.

Crystallization of aqueous ammonium sulfate particles internally mixed with soot and kaolinite: crystallization relative humidities and nucleation rates.

Science.gov (United States)

Pant, Atul; Parsons, Matthew T; Bertram, Allan K

2006-07-20

Using optical microscopy, we investigated the crystallization of aqueous ammonium sulfate droplets containing soot and kaolinite, as well as the crystallization of aqueous ammonium sulfate droplets free of solid material. Our results show that soot did not influence the crystallization RH of aqueous ammonium sulfate particles under our experimental conditions. In contrast, kaolinite increased the crystallization RH of the aqueous ammonium sulfate droplets by approximately 10%. In addition, our results show that the crystallization RH of aqueous ammonium sulfate droplets free of solid material does not depend strongly on particle size. This is consistent with conclusions made previously in the literature, based on comparisons of results from different laboratories. From the crystallization results we determined the homogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate droplets and the heterogeneous nucleation rates of crystalline ammonium sulfate in aqueous ammonium sulfate particles containing kaolinite. Using classical nucleation theory and our experimental data, we determined that the interfacial tension between an ammonium sulfate critical nucleus and an aqueous ammonium sulfate solution is 0.064 +/- 0.003 J m(-2) (in agreement with our previous measurements), and the contact angle between an ammonium sulfate critical nucleus and a kaolinite surface is 59 +/- 2 degrees. On the basis of our results, we argue that soot will not influence the crystallization RH of aqueous ammonium sulfate droplets in the atmosphere, but kaolinite can significantly modify the crystallization RH of atmospheric ammonium sulfate droplets. As an example, the CRH50 (the relative humidity at which 50% of the droplets crystallize) ranges from about 41 to 51% RH when the diameter of the kaolinite inclusion ranges from 0.1 to 5 microm. For comparison, the CRH50 of aqueous ammonium sulfate droplets (0.5 microm diameter) free of solid material is

Long-Term Stability Testing Results Using Surrogates And Sorbents For Savannah River Site Organic And Aqueous Wastestreams - 10016

International Nuclear Information System (INIS)

Burns, H.

2009-01-01

The U.S. Department of Energy (DOE) has tasked MSE Technology Applications, Inc. (MSE) with evaluating the long-term stability of various commercially available sorbent materials to solidify two organic surrogate wastestreams (both volatile and nonvolatile), a volatile organic surrogate with a residual aqueous phase, an aqueous surrogate, and an aqueous surrogate with a residual organic phase. The Savannah River Site (SRS) Legacy and F-Canyon plutonium/uranium extraction (PUREX) process waste surrogates constituted the volatile organic surrogates, and various oils constituted the nonvolatile organic surrogates. The aqueous surrogates included a rainwater surrogate and an aqueous organic surrogate. MSE also evaluated the PUREX surrogate with a residual aqueous component with and without aqueous type sorbent materials. Solidification of the various surrogate wastestreams listed above was performed from 2004 to 2006 at the MSE Test Facility located in Butte, Montana. This paper summarizes the comparison of the initial liquid release test (LRT) values with LRT results obtained during subsequent sampling events in an attempt to understand and define the long-term stability characteristics for the solidified wastestreams.

Aqueous-phase synthesis and color-tuning of core/shell/shell inorganic nanocrystals consisting of ZnSe, (Cu, Mn)-doped ZnS, and ZnS

Energy Technology Data Exchange (ETDEWEB)

Choi, Jongwan; Yoon, Sujin [Department of Chemistry and Research Institute for Natural Science, Hanyang University, Seoul, 133-791 (Korea, Republic of); Kim, Felix Sunjoo, E-mail: fskim@cau.ac.kr [School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul, 156-756 (Korea, Republic of); Kim, Nakjoong, E-mail: kimnj@hanyang.ac.kr [Department of Chemistry and Research Institute for Natural Science, Hanyang University, Seoul, 133-791 (Korea, Republic of)

2016-06-25

We report synthesis of colloidal nanocrystals based on ZnSe core, (Cu,Mn)-doped ZnS inner-shell, and ZnS outer-shell by using an eco-friendly method and their optical properties. Synthesis of core/shell/shell nanocrystals was performed by using a one-pot/three-step colloidal method with 3-mercaptopropionic acid as a stabilizer in aqueous phase at low temperature. A double-shell structure was employed with inner-shell as a host for doping and outer-shell as a passivation layer for covering surface defects. Copper and manganese were introduced as single- or co-dopants during inner-shell formation, providing an effective means to control the emission color of the nanocrystals. The synthesized nanocrystals showed fluorescent emission ranging from blue to green, to white, and to orange, adjusted by doping components, amounts, and ratios. The photoluminescence quantum yields of the core/doped-shell/shell nanocrystals approached 36%. - Highlights: • ZnSe/ZnS:(Cu,Ms)/ZnS core/(doped)shell/shell nanocrystals were synthesized in an aqueous phase. • Emission color of nanocrystals was controlled from blue to white to orange by adjusting the atomic ratio of Cu and Mn co-dopants. • Photoluminescence quantum yields of the colloidal nanocrystals approached 36%.

Los Angeles International Airport Runway Incursion Studies: Phase III--Center-Taxiway Simulation

Science.gov (United States)

Madson, Michael D.

2004-01-01

Phase III of the Los Angeles International Airport Runway Incursion Studies was conducted, under an agreement with HNTB Corporation, at the NASA Ames FutureFlight Central (FFC) facility in June 2003. The objective of the study was the evaluation of a new center-taxiway concept at LAX. This study is an extension of the Phase I and Phase II studies previously conducted at FFC. This report presents results from Phase III of the study, in which a center-taxiway concept between runways 25L and 25R was simulated and evaluated. Phase III data were compared objectively against the Baseline data. Subjective evaluations by participating LAX controllers were obtained with regard to workload, efficiency, and safety criteria. To facilitate a valid comparison between Baseline and Phase III data, the same scenarios were used for Phase III that were tested during Phases I and II. This required briefing participating controllers on differences in airport and airline operations between 2001 and today.

Variation in pH of Model Secondary Organic Aerosol during Liquid-Liquid Phase Separation.

Science.gov (United States)

Dallemagne, Magda A; Huang, Xiau Ya; Eddingsaas, Nathan C

2016-05-12

The majority of atmospheric aerosols consist of both organic and inorganic components. At intermediate relative humidity (RH), atmospheric aerosol can undergo liquid-liquid phase separation (LLPS) in which the organic and inorganic fractions segregate from each other. We have extended the study of LLPS to the effect that phase separation has on the pH of the overall aerosols and the pH of the individual phases. Using confocal microscopy and pH sensitive dyes, the pH of internally mixed model aerosols consisting of polyethylene glycol 400 and ammonium sulfate as well as the pH of the organic fraction during LLPS have been directly measured. During LLPS, the pH of the organic fraction was observed to increase to 4.2 ± 0.2 from 3.8 ± 0.1 under high RH when the aerosol was internally mixed. In addition, the high spatial resolution of the confocal microscope allowed us to characterize the composition of each of the phases, and we have observed that during LLPS the organic shell still contains large quantities of water and should be characterized as an aqueous organic-rich phase rather than simply an organic phase.

Digitally controlled measurement of sonic elastic moduli and internal friction by phase analysis

International Nuclear Information System (INIS)

O'Brien, M.H.; Hunter, O. Jr.; Rasmussen, M.D.; Skank, H.D.

1983-01-01

An automated system is described for measuring internal friction and elastic moduli using sonic resonance techniques. This mirocomputer-controlled device does phase angle analysis in addition to traditional decay and peak-width internal friction measurement. The apparatus may be programmed to make measurements at any sequence of temperatures between room temperature and 1600 0 C

Iron oxide functionalized graphene nano-composite for dispersive solid phase extraction of chemical warfare agents from aqueous samples.

Science.gov (United States)

Chinthakindi, Sridhar; Purohit, Ajay; Singh, Varoon; Tak, Vijay; Goud, D Raghavender; Dubey, D K; Pardasani, Deepak

2015-05-15

Present study deals with the preparation and evaluation of graphene based magnetic nano-composite for dispersive solid phase extraction of Chemical Weapons Convention (CWC) relevant chemicals from aqueous samples. Nano-composite, Fe3O4@SiO2-G was synthesized by covalently bonding silica coated Fe3O4 onto the graphene sheets. Nerve agents (NA), Sulfur mustard (SM) and their non-toxic environmental markers were the target analytes. Extraction parameters like amount of sorbent, extraction time and desorption conditions were optimized. Dispersion of 20 milligram of sorbent in 200mL of water sample for 20min. followed by methanol/chloroform extraction produced average to good recoveries (27-94%) of targeted analytes. Recoveries of real agents exhibited great dependency upon sample pH and ionic strength. Sarin produced maximum recovery under mild acidic conditions (56% at pH 5) while VX demanded alkaline media (83% at pH 9). Salts presence in the aqueous samples was found to be advantageous, raising the recoveries to as high as 94% for SM. Excellent limits of detection (LOD) for sulphur mustard and VX (0.11ngmL(-1) and 0.19ngmL(-1) respectively) proved the utility of the developed method for the off-site analysis of CWC relevant chemicals. Copyright © 2015 Elsevier B.V. All rights reserved.

Separation and Preconcentration of Trace Amounts of Nickel from Aqueous Samples

Directory of Open Access Journals (Sweden)

Reyhaneh Rahnama

2018-05-01

Full Text Available In this paper, a new method for preconcentration and measurement of trace amounts of nickel in aqueous samples by magnetic solid phase extraction (MSPE via magnetic carbon nanotubes (Mag-CNTs was developed. In order to increase selectivity, α-Furildioxime was used as chelating agent. In order to do extraction, optimum amount of ligand was added to the nickel sample and pH was set on 9, then 7 ml. of adsorbent was added and stirred for 15 minutes. After that, aqueous phase and adsorbent were separated by a strong magnet. Finally, the absorption was measured via flame atomic absorption spectrometry by analyte elution from the absorbent with an appropriate solution. Parameters affecting the extraction and preconcentration of nickel were investigated and optimized. Under optimum conditions, the calibration curve was linear in concentration range from 2.5 to 375 µg L-1 and the detection limit was 0.8 µg L-1 of nickel. The method was applied for determination of nickel in aqueous samples. The relative efficiency values of nickel measurement in aqueous samples were from 98.7% to 102.1%.  Results indicated that Mag-CNTs can be used as an effective and inexpensive absorbent for preconcentration and extraction of nickel from actual samples.

Determination of Three-Dimensional Morphology and Inner Structure of Second-Phase Inclusions in Metals by Non-Aqueous Solution Electrolytic and Room Temperature Organic Methods

OpenAIRE

Jing Guo; Keming Fang; Hanjie Guo; Yiwa Luo; Shengchao Duan; Xiao Shi; Wensheng Yang

2018-01-01

The secondary-phase particles in metals, particularly those composed of non-metallic materials, are often detrimental to the mechanical properties of metals; thus, it is crucial to control inclusion formation and growth. One of the challenges is determining the three-dimensional morphology and inner structures of such inclusions. In this study, a non-aqueous solution electrolytic method and a room-temperature organic technique were developed based on the principle of electrochemistry to deter...

Nanostructured aqueous dispersions of citrem interacting with lipids and PEGylated lipids

DEFF Research Database (Denmark)

Hedegaard, S.F.; Nilsson, Christa; Laurinmäki, P.

2013-01-01

We report on the formation of nanostructured aqueous dispersions based on the negatively charged food-grade emulsifier citrem (citric acid esters of mono- and diglycerides). To our knowledge, this is the first report in the literature on the spontaneous formation of aqueous PEGylated and non-PEGy...... ) phase. Based on the SAXS results, the partial replacement of citrem by high amount of MO or PHYT induced the formation of hexosomes. The investigated dispersions of citrem could be attractive as nanocarriers of poorly water-soluble drugs and functional foods.......We report on the formation of nanostructured aqueous dispersions based on the negatively charged food-grade emulsifier citrem (citric acid esters of mono- and diglycerides). To our knowledge, this is the first report in the literature on the spontaneous formation of aqueous PEGylated and non...

Extraction of rare earth metals (3) from aqueous solutions containing thorium and uranyl nitrates

International Nuclear Information System (INIS)

Pyartman, A.K.; Kopyrin, A.A.; Berinskij, A.E.; Keskinov, V.A.

2000-01-01

Isotherms of extraction of rare earth metals (3) from aqueous solutions containing thorium and uranyl nitrates by solutions of tributylphosphate (TBP) and diisooctylmethylphosphonate (DIOMP) in kerosene at 298.15 Deg C and pH 1 are presented. Equations for description of interphase distribution of components of the systems considered are suggested. These equations describe distribution of components adequately in the systems of thorium nitrate (uranyl nitrate) - rare earth nitrates - (TBP, DIOMP) in the case of wide variation of phase compositions. Dependences of separation factors on composition of aqueous phase are considered [ru

Internal friction and lattice anomalies of single-phase Hg-1223

International Nuclear Information System (INIS)

Zhang, Q.M.; Nanjing Univ.; Shao, H.M.; Nanjing Univ.; Huang, Y.N.; Nanjing Univ.; Shen, H.M.; Nanjing Univ.; Wang, Y.N.; Nanjing Univ.

1997-01-01

Internal friction in the kHz range has been performed for single-phase HgBa 2 Ca 2 Cu 3 O 8+δ with the critical temperature T c = 120 K. The results indicate that two peaks of internal friction appear near 150 and 250 K. X-ray diffraction exhibits a lattice parameter stepping at tens of Kelvin above T c . The Grueneisen parameter γ is estimated from the value of thermal expansion coefficients obtained from X-ray diffraction measurements. The discussion suggests that the anomaly at 150 K is caused by lattice instabilities and the other one near 250 K may be associated with a Neel transition. (orig.)

Purification process for aqueous solutions of rare earths by liquid-liquid extraction

International Nuclear Information System (INIS)

Rollat, A.; Sabot, J.L.; Burgard, M.; Delloye, T.

1986-01-01

Alkaline earth metals are removed by liquid-liquid extraction between on aqueous nitric phase of impure rare earth compounds and an organic phase of polyether (crown ether). This process is particularly suited to removal of Ca, Ba and Ra contained in nitric solutions of rare earths [fr

Acidities of Water and Methanol in Aqueous Solution and DMSO

Science.gov (United States)

Gao, Daqing

2009-01-01

The relative acidities of water and methanol have been a nagging issue. In gas phase, methanol is more acidic than water by 36.0 kJ/mol; however, in aqueous solution, the acidities of methanol and water are almost identical. The acidity of an acid in solution is determined by both the intrinsic gas-phase ionization Gibbs energy and the solvent…

Natural gas hydrate formation and inhibition in gas/crude oil/aqueous systems

DEFF Research Database (Denmark)

Daraboina, Nagu; Pachitsas, Stylianos; von Solms, Nicolas

2015-01-01

Gas hydrate formation in multi phase mixtures containing an aqueous phase (with dissolved salts), reservoir fluid (crude oil) and natural gas phase was investigated by using a standard rocking cell (RC-5) apparatus. The hydrate formation temperature was reduced in the presence of crude oils...... can contribute to the safe operation of sub sea pipelines in the oil and gas industry....

Partitioning in aqueous two-phase systems: Analysis of strengths, weaknesses, opportunities and threats.

Science.gov (United States)

Soares, Ruben R G; Azevedo, Ana M; Van Alstine, James M; Aires-Barros, M Raquel

2015-08-01

For half a century aqueous two-phase systems (ATPSs) have been applied for the extraction and purification of biomolecules. In spite of their simplicity, selectivity, and relatively low cost they have not been significantly employed for industrial scale bioprocessing. Recently their ability to be readily scaled and interface easily in single-use, flexible biomanufacturing has led to industrial re-evaluation of ATPSs. The purpose of this review is to perform a SWOT analysis that includes a discussion of: (i) strengths of ATPS partitioning as an effective and simple platform for biomolecule purification; (ii) weaknesses of ATPS partitioning in regard to intrinsic problems and possible solutions; (iii) opportunities related to biotechnological challenges that ATPS partitioning may solve; and (iv) threats related to alternative techniques that may compete with ATPS in performance, economic benefits, scale up and reliability. This approach provides insight into the current status of ATPS as a bioprocessing technique and it can be concluded that most of the perceived weakness towards industrial implementation have now been largely overcome, thus paving the way for opportunities in fermentation feed clarification, integration in multi-stage operations and in single-step purification processes. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Slow growth of the Rayleigh-Plateau instability in aqueous two phase systems

NARCIS (Netherlands)

Geschiere, S.D.; Ziemecka, I.; Van Steijn, V.; Koper, G.J.M.; Van Esch, J.H.; Kreutzer, M.T.

2012-01-01

This paper studies the Rayleigh-Plateau instability for co-flowing immiscible aqueous polymer solutions in a microfluidic channel. Careful vibration-free experiments with controlled actuation of the flow allowed direct measurement of the growth rate of this instability. Experiments for the

Partition thermodynamics of ionic surfactants between phosphatidylcholine vesicle and water phases

Science.gov (United States)

Chu, Shin-Chi; Hung, Chia-Hui; Wang, Shun-Cheng; Tsao, Heng-Kwong

2003-08-01

The partition of ionic surfactants (sodium alkyl sulfate and alkyl trimethyl ammonium bromide) between phosphatidylcholine vesicles and aqueous phase is investigated by simple conductometry under different temperatures. The experimental results can be well represented by the proposed regular solution theory and the thermodynamic parameters satisfy the thermodynamic consistency. The deviation from ideal partition is manifested through the effective interaction energy between lipid and surfactant wb, which is O(kT) large. It is found that wb rises as the alkyl chain is decreased for a specified head group. This is attributed to significant mismatch of chain lengths between surfactant and lipid molecules. The partition coefficient K declines with increasing temperature. The energy barrier from bilayer to aqueous phase, Δμ/kT∝ln K, is in the range of 16-26 kJ/mol. As the alkyl chain length is decreased for a given head group, Δμ is lowered by 1.3-1.5 kJ/mol per methylene group. Two independent analyses are employed to confirm this result. Using the thermodynamic parameters determined from experiments, the internal energy, entropy, and free energy of the partition process can be derived. Partition is essentially driven by the internal energy gain. The solubilizing ability, which is represented by the maximum surfactant-lipid ratio in the bilayer, Reb also decreases in accord with the K parameter. It is because the change in temperature influences the surfactant incorporation into the bilayer more than the formation of micelles.

Primitive Liquid Water of the Solar System in an Aqueous Altered Carbonaceous Chondrite

Science.gov (United States)

Tsuchiyama, A.; Miyake, A.; Kitayama, A.; Matsuno, J.; Takeuchi, A.; Uesugi, K.; Suzuki, Y.; Nakano, T.; Zolensky, M. E.

2016-01-01

Non-destructive 3D observations of the aqueous altered CM chondrite Sutter's Mill using scanning imaging x-ray microscopy (SIXM) showed that some of calcite and enstatite grains contain two-phase inclusion, which is most probably composed of liquid water and bubbles. This water should be primitive water responsible for aqueous alteration in an asteroid in the early solar system.

Cobalt ferrite nanoparticles with improved aqueous colloidal stability and electrophoretic mobility

International Nuclear Information System (INIS)

Munjal, Sandeep; Khare, Neeraj

2016-01-01

We have synthesized CoFe 2 O 4 (CFO) nanoparticles of size ∼ 12.2 nm by hydrothermal synthesis method. To control the size of these CFO nanoparticles, oleic acid was used as a surfactant. The inverse spinel phase of the synthesized nanoparticles was confirmed by X-ray diffraction method. As synthesized oleic acid coated CFO (OA@CFO) nanoparticles has very less electrophoretic mobility in the water and are not water dispersible. These OA@CFO nanoparticles were successfully turned into water soluble phase with a better colloidal aqueous stability, through a chemical treatment using citric acid. The modified citric acid coated CFO (CA@CFO) nanoparticles were dispersible in water and form a stable aqueous solution with high electrophoretic mobility.

Use of a Combined Technology of Ultrasonication, Three-Phase Partitioning, and Aqueous Enzymatic Oil Extraction for the Extraction of Oil from Spirogyra sp.

Directory of Open Access Journals (Sweden)

Adisheshu Reddy

2014-01-01

Full Text Available Algal oil from Spirogyra sp. was extracted using a combined technology of ultrasonication, three-phase partitioning, and aqueous enzymatic oil extraction. Ultrasonication was done to rupture the cell wall and papain was used for an easier release of the trapped oil. The salt concentration for three-phase partitioning, preincubation period with (or without the protease, and its operational temperature were optimized for a maximum possible yield of the oil and the effect of ultrasonication, and three-phase partitioning with (or without the protease were studied. It was found that under optimized conditions at 50% ammonium sulphate concentration using tert-butanol (in 1 : 1, v/v ratio a presonicated and papain treated algal suspension could produce 24% (w/w, dry weight oil within few hours which was ten times higher as compared to the oil obtained by Soxhlet extraction using hexane and two times higher than the oil obtained without using the protease.

Partition efficiencies of newly fabricated universal high-speed counter-current chromatograph for separation of two different types of sugar derivatives with organic-aqueous two-phase solvent systems

Science.gov (United States)

Shinomiya, Kazufusa; Sato, Kazuki; Yoshida, Kazunori; Tokura, Koji; Maruyama, Hiroshi; Yanagidaira, Kazuhiro; Ito, Yoichiro

2013-01-01

Universal high-speed counter-current chromatograph (HSCCC) was newly designed and fabricated in our laboratory. It holds a set of four column holders symmetrically around the rotary frame at a distance of 11.2 cm from the central axis. By engaging the stationary gear on the central axis of the centrifuge to the planetary gears on the column holder shaft through a set of idle gears, two pairs of diagonally located column holders simultaneously rotate about their own axes in the opposite directions: one forward (type-J planetary motion) and the other backward (type-I planetary motion) each synchronously with the revolution. Using the eccentric coil assembly, partition efficiencies produced by these two planetary motions were compared on the separation of two different types of sugar derivatives (4-methylumbelliferyl and 5-bromo-4-chloro-3-indoxyl sugar derivatives) using organic-aqueous two-phase solvent systems composed of n-hexane/ethyl acetate/1-butanol/methanol/water and aqueous 0.1 M sodium tetraborate, respectively. With lower phase mobile, better peak resolution was obtained by the type-J forward rotation for both samples probably due to higher retention of the stationary phase. With upper phase mobile, however, similar peak resolutions were obtained between these two planetary motions for both sugar derivatives. The overall results indicate that the present universal HSCCC is useful for counter-current chromatographic separation since each planetary motion has its specific applications: e.g., vortex CCC by the type-I planetary motion and HSCCC by the type-J planetary motion both for separation of various natural and synthetic products. PMID:24267319

Extraction and purification of capsaicin from capsicum oleoresin using an aqueous two-phase system combined with chromatography.

Science.gov (United States)

Fan, Yong; Lu, Yan-Min; Yu, Bin; Tan, Cong-Ping; Cui, Bo

2017-09-15

Capsaicin was extracted from capsicum oleoresin using an aqueous two-phase system (ATPS) composed of an ethylene oxide-propylene oxide (EOPO) copolymer, salt and ethanol. Capsaicin was concentrated in the top polymer-rich phase. To determine the optimal conditions, the partitioning of capsaicin in the ATPS was investigated, considering a single-factor experiment including the salt concentration, polymer concentration, buffer pH, ethanol concentration, sample loading and extraction duration. Response surface methodology was applied to investigate the effects of the polymer concentration, buffer pH and sample loading on capsaicin partitioning. A capsaicin yield of 95.5% was obtained using the optimal extraction system, which consisted of 16.3% UCON 50-HB-5100/10% K 2 HPO 4 /1% ethanol, a buffer pH of 4.35 and 0.24g of capsicum oleoresin. Capsaicin was purified from the capsaicinoid extract using a two-step macroporous adsorption resin (MAR) method. After purification using non-polar MAR ADS-17, the recovery and purity of capsaicin were 83.7% and 50.3%, respectively. After purification using weakly polar MAR AB-8, the recovery and purity of capsaicin were 88.0% and 85.1%, respectively. Copyright © 2017. Published by Elsevier B.V.

Recovery of laccase from processed Hericium erinaceus (Bull.:Fr) Pers. fruiting bodies in aqueous two-phase system.

Science.gov (United States)

Rajagopalu, Devamalini; Show, Pau Loke; Tan, Yee Shin; Muniandy, Sekaran; Sabaratnam, Vikineswary; Ling, Tau Chuan

2016-09-01

The feasible use of aqueous two-phase systems (ATPSs) to establish a viable protocol for the recovery of laccase from processed Hericium erinaceus (Bull.:Fr.) Pers. fruiting bodies was evaluated. Cold-stored (4.00±1.00°C) H. erinaceus recorded the highest laccase activities of 2.02±0.04 U/mL among all the processed techniques. The evaluation was carried out in twenty-five ATPSs, which composed of polyethylene glycol (PEG) with various molecular weights and potassium phosphate salt solution to purify the protein from H. erinaceus. Optimum recovery condition was observed in the ATPS which contained 17% (w/w) PEG with a molecular weight of 8000 and 12.2% (w/w) potassium phosphate solution, at a volume ratio (VR) of 1.0. The use of ATPS resulted in one-single primary recovery stage process that produced an overall yield of 99% with a purification factor of 8.03±0.46. The molecular mass of laccases purified from the bottom phase was in the range of 55-66 kDa. The purity of the partitioned laccase was confirmed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Quantitative characterization of the aqueous fraction from hydrothermal liquefaction of algae

Energy Technology Data Exchange (ETDEWEB)

Maddi, Balakrishna; Panisko, Ellen; Wietsma, Thomas; Lemmon, Teresa; Swita, Marie; Albrecht, Karl; Howe, Daniel

2016-10-01

Aqueous streams generated from hydrothermal liquefaction contain approximately 30% of the total carbon present from the algal feed. Hence, this aqueous carbon must be utilized to produce liquid fuels and/or specialty chemicals for economic sustainability of hydrothermal liquefaction on industrial scale. In this study, aqueous fractions produced from the hydrothermal liquefaction of fresh water and saline water algal cultures were analyzed using a wide variety of analytical instruments to determine their compositional characteristics. This study will also inform researchers designing catalysts for down-stream processing such as high-pressure catalytic conversion of organics in aqueous phase, catalytic hydrothermal gasification, and biological conversions. Organic chemical compounds present in all eight aqueous fractions were identified using two-dimensional gas chromatography equipped with time-of-flight mass spectrometry. Identified compounds include organic acids, nitrogen compounds and aldehydes/ketones. Conventional gas chromatography and liquid chromatography methods were utilized to quantify the identified compounds. Inorganic species in the aqueous stream of hydrothermal liquefaction of algae were identified using ion chromatography and inductively coupled plasma optical emission spectrometer. The concentrations of organic chemical compounds and inorganic species are reported. The amount quantified carbon ranged from 45 to 72 % of total carbon in the aqueous fractions.

Characterization of bovine serum albumin partitioning behaviors in polymer-salt aqueous two-phase systems.

Science.gov (United States)

Chow, Yin Hui; Yap, Yee Jiun; Tan, Chin Ping; Anuar, Mohd Shamsul; Tejo, Bimo Ario; Show, Pau Loke; Ariff, Arbakariya Bin; Ng, Eng-Poh; Ling, Tau Chuan

2015-07-01

In this paper, a linear relationship is proposed relating the natural logarithm of partition coefficient, ln K for protein partitioning in poly (ethylene glycol) (PEG)-phosphate aqueous two-phase system (ATPS) to the square of tie-line length (TLL(2)). This relationship provides good fits (r(2) > 0.98) to the partition of bovine serum albumin (BSA) in PEG (1450 g/mol, 2000 g/mol, 3350 g/mol, and 4000 g/mol)-phosphate ATPS with TLL of 25.0-50.0% (w/w) at pH 7.0. Results also showed that the plot of ln K against pH for BSA partitioning in the ATPS containing 33.0% (w/w) PEG1450 and 8.0% (w/w) phosphate with varied working pH between 6.0 and 9.0 exhibited a linear relationship which is in good agreement (r(2) = 0.94) with the proposed relationship, ln K = α' pH + β'. These results suggested that both the relationships proposed could be applied to correlate and elucidate the partition behavior of biomolecules in the polymer-salt ATPS. The influence of other system parameters on the partition behavior of BSA was also investigated. An optimum BSA yield of 90.80% in the top phase and K of 2.40 was achieved in an ATPS constituted with 33.0% (w/w) PEG 1450 and 8.0% (w/w) phosphate in the presence of 8.5% (w/w) sodium chloride (NaCl) at pH 9.0 for 0.3% (w/w) BSA load. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

In situ observation of sol-gel transition of agarose aqueous solution by fluorescence measurement.

Science.gov (United States)

Wang, Zheng; Yang, Kun; Li, Haining; Yuan, Chaosheng; Zhu, Xiang; Huang, Haijun; Wang, Yongqiang; Su, Lei; Fang, Yapeng

2018-06-01

Sol-gel transition behavior of agarose aqueous solution was investigated by using rheology and fluorescence measurement. On heating, the storage modulus G' decreased gradually, then deviated abruptly at the temperature of about 65°C, and finally decreased slowly again. For fluorescence measurement, the phase transition point kept almost at the temperature of 65°C, which was consistent with that in rheology measurement. Upon compression, it was indicated that the fluorescence lifetime for the probe in the agarose aqueous solution showed a dramatic change in the vicinity of the phase transition point. T vs. P phase diagram of agarose aqueous solution was constructed, which showed that the melting point was an increasing function of pressure. Based on the phase diagram, the agarose gels were prepared by cooling under atmospheric pressure and the pressure of 300MPa, respectively. From the result of the recovered samples studied by optical rheometry, it was found that agarose gel prepared under high pressure had a higher elasticity and lower viscosity index, compared with that under atmospheric pressure. It could be speculated that such kinds of properties might be attributed to the smaller pore size during gelation under high pressure. Copyright © 2018. Published by Elsevier B.V.

Carbon Mineralization by Aqueous Precipitation for Beneficial Use of CO2 from Flue Gas. Phase I. Final Topical Report

International Nuclear Information System (INIS)

Constantz, Brent; Seeker, Randy; Devenney, Martin

2010-01-01

Calera's innovative Mineralization via Aqueous Precipitation (MAP) technology for the capture and conversion of CO 2 to useful materials for use in the built environment was further developed and proven in the Phase 1 Department of Energy Grant. The process was scaled to 300 gallon batch reactors and subsequently to Pilot Plant scale for the continuous production of product with the production of reactive calcium carbonate material that was evaluated as a supplementary cementitious material (SCM). The Calera SCM(trademark) was evaluated as a 20% replacement for ordinary portland cement and demonstrated to meet the industry specification ASTM 1157 which is a standard performance specification for hydraulic cement. The performance of the 20% replacement material was comparable to the 100% ordinary portland cement control in terms of compressive strength and workability as measured by a variety of ASTM standard tests. In addition to the performance metrics, detailed characterization of the Calera SCM was performed using advanced analytical techniques to better understand the material interaction with the phases of ordinary portland cement. X-ray synchrotron diffraction studies at the Advanced Photon Source in Argonne National Lab confirmed the presence of an amorphous phase(s) in addition to the crystalline calcium carbonate phases in the reactive carbonate material. The presence of carboaluminate phases as a result of the interaction of the reactive carbonate materials with ordinary portland cement was also confirmed. A Life Cycle Assessment was completed for several cases based on different Calera process configurations and compared against the life cycle of ordinary portland cement. In addition to the materials development efforts, the Calera technology for the production of product using an innovative building materials demonstration plant was developed beyond conceptual engineering to a detailed design with a construction schedule and cost estimate.

Protonation site for anilines in aqueous media

Directory of Open Access Journals (Sweden)

INNA M. UCHAEVA

2002-02-01

Full Text Available By means of the PM3 method it has been shown that the protonation of 2-, 3-, 4-methoxyanilines, 4-methylthioaniline, 2-, 3-, 4-aminobenzoic acids, 2-, 3-, 4-nitroanilines in the gaseous phase proceeds via the amine nitrogen atom. The same result, attributed to the aqueous medium, was obtained for 4-methoxyaniline, 4-aminobenzoic acid and 4-nitroaniline.

Treatment of low and intermediate aqueous waste containing Cs-137 by chemical precipitation

International Nuclear Information System (INIS)

Valdezco, E.M.; Marcelo, E.A.; Alamares, A.L.; Junio, J.B.; Dela Cruz, J.M.

1996-01-01

The use of radioactive materials in various applications has been increasing since its introduction in the early sixties. The Philippine Nuclear Research Institute has established a centralized facility for treating radioactive wastes i.e. aqueous wastes with assistance from the International Atomic Energy Agency - Technical Cooperation Programme. Liquid wastes containing Cs-137 are generated from aqueous wastes containing Cs-137 by nickel ferrocyanide precipitation will be presented. The aim of this study is to investigate the efficiency treatment in removing Cs-137 from an aqueous effluent. Actual aqueous wastes known to contain Cs-137 were used in the experiments. Low cost and simple nickel ferrocyanide precipitation method with the aid of a flocculant has been selected for the separation of Cs-137 from low and intermediate aqueous waste. By varying the chemical dosage added into the aqueous waste, different decontamination factors were obtained. Hence, the optimum dosage of the chemicals that give the highest decontamination factor can be determined. (author)

Optimization of ultrasound-assisted aqueous two-phase system extraction of polyphenolic compounds from Aronia melanocarpa pomace by response surface methodology.

Science.gov (United States)

Xu, Yan-Yang; Qiu, Yang; Ren, Hui; Ju, Dong-Hu; Jia, Hong-Lei

2017-03-16

Aronia melanocarpa berries are abundant in polyphenolic compounds. After juice production, the pomace of pressed berries still contains a substantial amount of polyphenolic compounds. For efficient utilization of A. melanocarpa berries and the enhancement of polyphenolic compound yields in Aronia melanocarpa pomace (AMP), total phenolics (TP) and total flavonoids (TF) from AMP were extracted, using ultrasound-assisted aqueous two-phase system (UAE-ATPS) extraction method. First, the influences of ammonium sulfate concentration, ethanol-water ratio, ultrasonic time, and ultrasonic power on TP and TF yields were investigated. On this basis, process variables such as ammonium sulfate concentration (0.30-0.35 g mL -1 ), ethanol-water ratio (0.6-0.8), ultrasonic time (40-60 min), and ultrasonic power (175-225 W) were further optimized by implementing Box-Benhnken design with response surface methodology. The experimental results showed that optimal extraction conditions of TP from AMP were as follows: ammonium sulfate concentration of 0.324 g mL -1 , ethanol-water ratio of 0.69, ultrasonic time of 52 min, and ultrasonic power of 200 W. Meanwhile, ammonium sulfate concentration of 0.320 g mL -1 , ethanol-water ratio of 0.71, ultrasonic time of 50 min, and ultrasonic power of 200 W were determined as optimum extraction conditions of TF in AMP. Experimental validation was performed, where TP and TF yields reached 68.15 ± 1.04 and 11.67 ± 0.63 mg g -1 , respectively. Close agreement was found between experimental and predicted values. Overall, the present results demonstrated that ultrasound-assisted aqueous two-phase system extraction method was successfully used to extract total phenolics and flavonoids in A. melanocarpa pomace.

RECOVERY OF CARBOXYLIC ACIDS FROM AQUEOUS SOLUTIONS BY LIQUID-LIQUID EXTRACTION WITH A TRIISOOCTYLAMINE DILUENT SYSTEM

Directory of Open Access Journals (Sweden)

G. Malmary

2001-12-01

Full Text Available Tertiary alkylamines in solution with organic diluents are attractive extractants for the recovery of carboxylic acids from dilute aqueous phases. The aim of this study was to investigate the mechanism for extraction of organic acids from water by a long-chain aliphatic tertiary amine. In order to attain this objective, we studied the liquid-liquid equilibria between the triisooctylamine + 1-octanol + n-heptane system as solvent and an aqueous solution of an individual carboxylic acid such as citric, lactic and malic acids. The experiments showed that the partition coefficient for a particular organic acid depends on the kind of solute, notably when the acid concentration in the aqueous phase is low. A mathematical model, where both chemical association and physical distribution are taken into consideration, is proposed. The model suggests that the various complexes obtained between amine and organic acids contribute to the distribution of the solute between the coexisting phases in equilibrium.

Hydrogen evolution from aqueous-phase photocatalytic reforming of ethylene glycol over Pt/TiO{sub 2} catalysts: Role of Pt and product distribution

Energy Technology Data Exchange (ETDEWEB)

Li, Fuying [State Key Laboratory of Photocatalysis on Energy and Environment, Research Institute of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); College of Resources and Chemical Engineering, Sanming University, Sanming 365004 (China); Gu, Quan [Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shanxi Normal University, Xi’an 710062 (China); Niu, Yu [College of Resources and Chemical Engineering, Sanming University, Sanming 365004 (China); School of Chemical Engineering, Fuzhou University, Fuzhou 350116 (China); Wang, Renzhang [College of Resources and Chemical Engineering, Sanming University, Sanming 365004 (China); Tong, Yuecong; Zhu, Shuying; Zhang, Hualei [State Key Laboratory of Photocatalysis on Energy and Environment, Research Institute of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Zhang, Zizhong, E-mail: z.zhang@fzu.edu.cn [State Key Laboratory of Photocatalysis on Energy and Environment, Research Institute of Photocatalysis, Fuzhou University, Fuzhou 350002 (China); Wang, Xuxu [State Key Laboratory of Photocatalysis on Energy and Environment, Research Institute of Photocatalysis, Fuzhou University, Fuzhou 350002 (China)

2017-01-01

Highlights: • Photocatalytic EG reforming generates many hydrocarbons besides H{sub 2}, CO{sub 2} and CO. • Pt loading greatly improves the photocatalytic activity of TiO{sub 2} for EG reforming. • Half amount of the produced H{sub 2} over Pt/TiO{sub 2} originates from EG reforming. - Abstract: Pt nanoparticles were loaded on anatase TiO{sub 2} by the photodeposition method to investigate their photocatalytic activity for H{sub 2} evolution in an aqueous solution containing a certain amount of ethylene glycol (EG) as the sacrificial agent. The surface properties and chemical states of the Pt/TiO{sub 2} sample were characterized by X-ray powder diffraction analysis, Brunauer–Emmett–Teller surface area analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, electron paramagnetic resonance, and electrochemical resistance. The aqueous-phase photocatalytic EG reforming using Pt/TiO{sub 2} and anatase TiO{sub 2} generated not only H{sub 2} and CO{sub 2}, but also CO, CH{sub 4}, C{sub 2}H{sub 6}, and C{sub 2}H{sub 4}. Moreover, the amount of formate and acetate complexes in the solution increased gradually. The EG adsorption and gas-phase intermediates during photocatalytic reaction processes were investigated by the in situ FTIR spectrum. Finally, the photocatalytic EG reforming reaction mechanism was elucidated. This helped to better understand the role of a sacrificial agent in a photocatalytic hydrogen production.

Trace-level mercury ion (Hg2+) analysis in aqueous sample based on solid-phase extraction followed by microfluidic immunoassay.

Science.gov (United States)

Date, Yasumoto; Aota, Arata; Terakado, Shingo; Sasaki, Kazuhiro; Matsumoto, Norio; Watanabe, Yoshitomo; Matsue, Tomokazu; Ohmura, Naoya

2013-01-02

Mercury is considered the most important heavy-metal pollutant, because of the likelihood of bioaccumulation and toxicity. Monitoring widespread ionic mercury (Hg(2+)) contamination requires high-throughput and cost-effective methods to screen large numbers of environmental samples. In this study, we developed a simple and sensitive analysis for Hg(2+) in environmental aqueous samples by combining a microfluidic immunoassay and solid-phase extraction (SPE). Using a microfluidic platform, an ultrasensitive Hg(2+) immunoassay, which yields results within only 10 min and with a lower detection limit (LOD) of 0.13 μg/L, was developed. To allow application of the developed immunoassay to actual environmental aqueous samples, we developed an ion-exchange resin (IER)-based SPE for selective Hg(2+) extraction from an ion mixture. When using optimized SPE conditions, followed by the microfluidic immunoassay, the LOD of the assay was 0.83 μg/L, which satisfied the guideline values for drinking water suggested by the United States Environmental Protection Agency (USEPA) (2 μg/L; total mercury), and the World Health Organisation (WHO) (6 μg/L; inorganic mercury). Actual water samples, including tap water, mineral water, and river water, which had been spiked with trace levels of Hg(2+), were well-analyzed by SPE, followed by microfluidic Hg(2+) immunoassay, and the results agreed with those obtained from reduction vaporizing-atomic adsorption spectroscopy.

Short Range-Ordered Minerals: Insight into Aqueous Alteration Processes on Mars

Science.gov (United States)

Ming, Douglas W.; Morris, R. V.; Golden, D. C.

2011-01-01

Short range-ordered (SRO) aluminosilicates (e.g., allophane) and nanophase ferric oxides (npOx) are common SRO minerals derived during aqueous alteration of basaltic materials. NpOx refers to poorly crystalline or amorphous alteration products that can be any combination of superparamagnetic hematite and/or goethite, akaganeite, schwertmannite, ferrihydrite, iddingsite, and nanometer-sized ferric oxide particles that pigment palagonitic tephra. Nearly 30 years ago, SRO phases were suggested as alteration phases on Mars based on similar spectral properties for altered basaltic tephra on the slopes of Mauna Kea in Hawaii and Martian bright regions measured by Earth-based telescopes. Detailed characterization of altered basaltic tephra on Mauna Kea have identified a variety of alteration phases including allophane, npOx, hisingerite, jarosite, alunite, hematite, goethite, ferrihydrite, halloysite, kaolinite, smectite, and zeolites. The presence of npOx and other Fe-bearing minerals (jarosite, hematite, goethite) was confirmed by the M ssbauer Spectrometer onboard the Mars Exploration Rovers. Although the presence of allophane has not been definitely identified on Mars robotic missions, chemical analysis by the Spirit and Opportunity rovers and thermal infrared spectral orbital measurements suggest the presence of allophane or allophane-like phases on Mars. SRO phases form under a variety of environmental conditions on Earth ranging from cold and arid to warm and humid, including hydrothermal conditions. The formation of SRO aluminosilicates such as allophane (and crystalline halloysite) from basaltic material is controlled by several key factors including activity of water, extent of leaching, Si activity in solution, and available Al. Generally, a low leaching index (e.g., wet-dry cycles) and slightly acidic to alkaline conditions are necessary. NpOx generally form under aqueous oxidative weathering conditions, although thermal oxidative alteration may occasional be

UV Resonance Raman Elucidation of the Terminal and Internal Peptide Bond Conformations of Crystalline and Solution Oligoglycines.

Science.gov (United States)

Bykov, Sergei V; Asher, Sanford A

2010-11-30

Spectroscopic investigations of macromolecules generally attempt to interpret the measured spectra in terms of the summed contributions of the different molecular fragments. This is the basis of the local mode approximation in vibrational spectroscopy. In the case of resonance Raman spectroscopy independent contributions of molecular fragments require both a local mode-like behavior and the uncoupled electronic transitions. Here we show that the deep UV resonance Raman spectra of aqueous solution phase oligoglycines show independent peptide bond molecular fragment contributions indicating that peptide bonds electronic transitions and vibrational modes are uncoupled. We utilize this result to separately determine the conformational distributions of the internal and penultimate peptide bonds of oligoglycines. Our data indicate that in aqueous solution the oligoglycine terminal residues populate conformations similar to those found in crystals (3(1)-helices and β-strands), but with a broader distribution, while the internal peptide bond conformations are centered around the 3(1)-helix Ramachandran angles.

Influence of salts on the coexistence curve and protein partitioning in nonionic aqueous two-phase micellar systems

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A. M. Lopes

2014-12-01

Full Text Available Aqueous two-phase micellar systems (ATPMS can be exploited in separation science for the extraction/purification of desired biomolecules. Prior to phase separation the surfactant solution reaches a cloud point temperature, which is influenced by the presence of electrolytes. In this work, we provide an investigation on the cloud point behavior of the nonionic surfactant C10E4 in the presence of NaCl, Li2SO4 and KI. We also investigated the salts' influence on a model protein partitioning. NaCl and Li2SO4 promoted a depression of the cloud point. The order of salts and the concentration that decreased the cloud point was: Li2SO4 0.5 M > NaCl 0.5 M ≈ Li2SO4 0.2 M. On the other hand, 0.5 M KI dislocated the curve to higher cloud point values. For our model protein, glucose-6-phosphate dehydrogenase (G6PD, partitioning experiments with 0.5 M NaCl or 0.2 M Li2SO4 at 13.85 ºC showed similar results, with K G6PD ~ 0.46. The lowest partition coefficient was obtained in the presence of 0.5 M KI (K G6PD = 0.12, with major recovery of the enzyme in the micelle-dilute phase (%Recovery = 90%. Our results show that choosing the correct salt to add to ATPMS may be useful to attain the desired partitioning conditions at more extreme temperatures. Furthermore, this system can be effective to separate a target biomolecule from fermented broth contaminants.

Determination of uranyl nitrate diffusion coefficients in organic and aqueous media using the porous diaphragm method

International Nuclear Information System (INIS)

Chierice, G.O.

1974-01-01

The diffusion coefficient is one of the parameters necessary for the obtention of the extraction exponential coefficients, that are contained within the H.T.U. (height of transfer unity) calculation expression, when operating with continuous organic phase. The organic phase used was tri-n-butyl-phosphate (TBP) and varsol in the 35% and 65% proportions respectively. After each experiment, the uranium content present in each compartment was spectrophotometrically determined and the quantities contained in the aqueous phases were determined by means of volumetric titration. It was found out that the uranyl ion diffusion coefficient is two and one half times less in organic phase, this just being attributed to the greater interactions of the uranyl ions in organic than in aqueous medium

Atmospheric plasma generates oxygen atoms as oxidizing species in aqueous solutions

Czech Academy of Sciences Publication Activity Database

Hefny, M.M.; Pattyn, C.; Lukeš, Petr; Benedikt, J.

2016-01-01

Roč. 49, č. 40 (2016), s. 404002 ISSN 0022-3727 R&D Projects: GA MŠk(CZ) LD14080 Grant - others:European Cooperation in Science and Technology(XE) COST TD1208 Institutional support: RVO:61389021 Keywords : atmospheric pressure plasma * transport of reactive species * reactive oxygen species * aqueous phase chemistry * plasma and liquids * phenol aqueous chemistry Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.588, year: 2016 http://iopscience.iop.org/article/10.1088/0022-3727/49/40/404002

Noble metal catalyzed aqueous phase hydrogenation and hydrodeoxygenation of lignin-derived pyrolysis oil and related model compounds.

Science.gov (United States)

Mu, Wei; Ben, Haoxi; Du, Xiaotang; Zhang, Xiaodan; Hu, Fan; Liu, Wei; Ragauskas, Arthur J; Deng, Yulin

2014-12-01

Aqueous phase hydrodeoxygenation of lignin pyrolysis oil and related model compounds were investigated using four noble metals supported on activated carbon. The hydrodeoxygenation of guaiacol has three major reaction pathways and the demethylation reaction, mainly catalyzed by Pd, Pt and Rh, produces catechol as the products. The presence of catechol and guaiacol in the reaction is responsible for the coke formation and the catalysts deactivation. As expected, there was a significant decrease in the specific surface area of Pd, Pt and Rh catalysts during the catalytic reaction because of the coke deposition. In contrast, no catechol was produced from guaiacol when Ru was used so a completely hydrogenation was accomplished. The lignin pyrolysis oil upgrading with Pt and Ru catalysts further validated the reaction mechanism deduced from model compounds. Fully hydrogenated bio-oil was produced with Ru catalyst. Copyright © 2014 Elsevier Ltd. All rights reserved.

Removal of uranium(VI) from the aqueous phase by iron(II) minerals in presence of bicarbonate

Energy Technology Data Exchange (ETDEWEB)

Regenspurg, Simona, E-mail: regens@gfz-potsdam.de [Industrial Ecology, Royal Institute of Technology (KTH), SE 10044 Stockholm (Sweden); Schild, Dieter; Schaefer, Thorsten; Huber, Florian [Institut fuer Nukleare Entsorgung (INE), Forschungszentrum Karlsruhe, 76344 Eggenstein-Leopoldshafen (Germany); Malmstroem, Maria E. [Industrial Ecology, Royal Institute of Technology (KTH), SE 10044 Stockholm (Sweden)

2009-09-15

Uranium(VI) mobility in groundwater is strongly affected by sorption of mobile U(VI) species (e.g. uranyl, UO{sub 2}{sup 2+}) to mineral surfaces, precipitation of U(VI) compounds, such as schoepite (UO{sub 2}){sub 4}O(OH){sub 6}.6H{sub 2}O), and by reduction to U(IV), forming sparingly soluble phases (uraninite; UO{sub 2}). The latter pathway, in particular, would be very efficient for long-term immobilization of U. In nature, Fe(II) is an important reducing agent for U(VI) because it frequently occurs either dissolved in natural waters, sorbed to matrix minerals, or structurally bound in many minerals. Redox reactions between U(VI) and Fe(II) depend not only on the availability of Fe(II) in the environment, but also on the chemical conditions in the aqueous solution. Under natural groundwater condition U(VI) forms complexes with many anionic ligands, which strongly affect its speciation. Carbonate, in particular, is known to form stable complexes with U, raising the question, if U(VI), when complexed by carbonate, can be reduced to UO{sub 2}. The goal of this study was to find out if Fe(II) when structurally bound in a mineral (as magnetite, Fe{sub 3}O{sub 4}) or sorbed to a mineral surface (as corundum, Al{sub 2}O{sub 3}) can reduce U(VI) to U(IV) in the presence of HCO{sub 3}{sup -}. Batch experiments were conducted under anaerobic conditions to observe U removal from the aqueous phase by the two minerals depending on HCO{sub 3}{sup -} addition (1 mM), U concentration (0.01-30 {mu}M) and pH value (6-10). Immediately after the experiments, the mineral surfaces were analyzed by X-ray photoelectron spectroscopy (XPS) to obtain information on the redox state of U bound to the solid surfaces. XPS results gave evidence that U(VI) can be reduced both by magnetite and by corundum amended with Fe(II). In the presence of HCO{sub 3}{sup -} the amount of reduced U on the mineral surfaces increased compared to carbonate-free solutions. This can be explained by the formation

Aqueous alteration of Japanese simulated waste glass P0798: Effects of alteration-phase formation on alteration rate and cesium retention

International Nuclear Information System (INIS)

Inagaki, Y.; Shinkai, A.; Idemistu, K.; Arima, T.; Yoshikawa, H.; Yui, M.

2006-01-01

Aqueous alteration tests were performed with a Japanese simulated waste glass P0798 in alkaline solutions as a function of pH or species/concentration of alkaline metals in the solution in order to evaluate the alteration conditions determining whether smectite (2:1 clay mineral) or analcime (zeolite) forms as the major alteration-phase. XRD analysis of the alteration-phases showed that smectite forms at any pH between 9.5 and 12, and analcime forms at pH above 11, though the formation also depends on species and concentrations of alkaline metals in the solution. These results cannot agree with the thermodynamically predicted phase stability, e.g., smectite is more stable than the thermodynamic prediction shows. On the basis of the results of alteration conditions, the alteration tests were performed under smectite forming conditions, where only smectite forms or no crystalline phases form, in order to evaluate the alteration rate and the mechanism of cesium release/retention. The results showed that the glass alteration proceeds slowly in proportion to square root of time under smectite forming conditions, which indicates that the alteration rate can be controlled by a diffusion process. It was suggested that the alteration rate under smectite forming conditions is independent of the pH, alkaline metal species/concentration in the solution and whether smectite actually forms or not. The results also indicated that most of cesium dissolved from the glass can be retained in the alteration-phases by reversible sorption onto smectite or irreversible incorporation into analcime, pollucite or solid solutions of them

A New Efficient Analytical Method for Picolinate Ion Measurements in Complex Aqueous Solutions

Energy Technology Data Exchange (ETDEWEB)

Parazols, M.; Dodi, A. [CEA Cadarache, Lab Anal Radiochim and Chim, DEN, F-13108 St Paul Les Durance (France)

2010-07-01

This study focuses on the development of a new simple but sensitive, fast and quantitative liquid chromatography method for picolinate ion measurement in high ionic strength aqueous solutions. It involves cation separation over a chromatographic CS16 column using methane sulfonic acid as a mobile phase and detection by UV absorbance (254 nm). The CS16 column is a high-capacity stationary phase exhibiting both cation exchange and RP properties. It allows interaction with picolinate ions which are in their zwitterionic form at the pH of the mobile phase (1.3-1.7). Analysis is performed in 30 min with a detection limit of about 0.05 {mu}M and a quantification limit of about 0.15 {mu}M. Moreover, this analytical technique has been tested efficiently on complex aqueous samples from an effluent treatment facility. (authors)

Secondary Organic Aerosol Formation from Acetylene (C2H2: seed effect on SOA yields due to organic photochemistry in the aerosol aqueous phase

Directory of Open Access Journals (Sweden)

P. J. Ziemann

2009-03-01

Full Text Available The lightest Non Methane HydroCarbon (NMHC, i.e., acetylene (C2H2 is found to form secondary organic aerosol (SOA. Contrary to current belief, the number of carbon atoms, n, for a NMHC to act as SOA precursor is lowered to n=2 here. The OH-radical initiated oxidation of C2H2 forms glyoxal (CHOCHO as the highest yield product, and >99% of the SOA from C2H2 is attributed to CHOCHO. SOA formation from C2H2 and CHOCHO was studied in a photochemical and a dark simulation chamber. Further, the experimental conditions were varied with respect to the chemical composition of the seed aerosols, mild acidification with sulphuric acid (SA, 3internally mixed inorganic/WSOC seed aerosols is found responsible for this seed effect. WSOC photochemistry enhances the SOA source from CHOCHO, while seeds containing amino acids (AA and/or SA showed among the lowest of all YSOA values, and largely suppress the photochemical enhancement on the rate of CHOCHO uptake. Our results give first evidence for the importance of heterogeneous photochemistry of CHOCHO in SOA formation, and identify a potential bias in the currently available YSOA data for other SOA precursor NMHCs. We demonstrate that SOA formation via the aqueous phase is not limited to cloud droplets, but proceeds also in the absence of clouds, i.e., does not stop once a cloud droplet evaporates. Atmospheric models need to be expanded to include SOA formation from WSOC photochemistry of CHOCHO, and possibly other α-dicarbonyls, in aqueous aerosols.

Aqueous phase reforming of ethylene glycol - Role of intermediates in catalyst performance

NARCIS (Netherlands)

de Vlieger, Dennis; Mojet, Barbara; Lefferts, Leonardus; Seshan, Kulathuiyer

2012-01-01

Liquid product formation during the aqueous catalytic reforming of ethylene glycol (EG) was studied up to 450 °C and 250 bar pressure. Methanol, ethanol, and acetic acid were the main liquid by-products during EG reforming in the presence of alumina-supported Pt and Pt–Ni catalysts. The effect of

Liquid Phase Micro-Extraction of Linear Alkylbenzene Sulfonate Anionic Surfactants in Aqueous Samples

Directory of Open Access Journals (Sweden)

Jan Åke Jönsson

2011-10-01

Full Text Available Hollow fiber liquid phase micro-extraction (LPME of linear alkylbenzene sulfonates (LAS from aqueous samples was studied. Ion pair extraction of C10, C11, C12 and C13 homologues was facilitated with trihexylamine as ion-pairing agent, using di-n-hexylether as solvent for the supported liquid membrane (SLM. Effects of extraction time, acceptor buffer concentration, stirring speed, sample volume, NaCl and humic acids were studied. At 10–50 µg L−1 linear R2-coefficients were 0.99 for C10 and C11 and 0.96 for C12. RSD was typically ~15%. Three observations were especially made. Firstly, LPME for these analytes was unusually slow with maximum enrichment observed after 15–24 h (depending on sample volume. Secondly, the enrichment depended on LAS sample concentration with 35–150 times enrichment below ~150 µg L−1 and 1850–4400 times enrichment at 1 mg L−1. Thirdly, lower homologues were enriched more than higher homologues at low sample concentrations, with reversed conditions at higher concentrations. These observations may be due to the fact that LAS and the amine counter ion themselves influence the mass transfer at the water-SLM interface. The observations on LPME of LAS may aid in LPME application to other compounds with surfactant properties or in surfactant enhanced membrane extraction of other compounds.

Characterization of fatty acid and triacylglycerol composition in animal fats using silver-ion and non-aqueous reversed-phase high-performance liquid chromatography/mass spectrometry and gas chromatography/flame ionization detection

Czech Academy of Sciences Publication Activity Database

Lísa, M.; Netušilová, K.; Franěk, L.; Dvořáková, H.; Vrkoslav, Vladimír; Holčapek, M.

2011-01-01

Roč. 1218, č. 42 (2011), s. 7499-7510 ISSN 0021-9673 R&D Projects: GA ČR GA203/09/0139 Institutional research plan: CEZ:AV0Z40550506 Keywords : silver-ion HPLC * non-aqueous reversed-phase HPLC * triacylglycerol Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.531, year: 2011

Carbon nanoparticles from corn stalk soot and its novel application as stationary phase of hydrophilic interaction chromatography and per aqueous liquid chromatography

International Nuclear Information System (INIS)

Li Yuanyuan; Xu Luan; Chen Tong; Liu Xiaoyan; Xu Zhigang; Zhang Haixia

2012-01-01

Highlights: ► Carbon nanoparticles (6–18 nm in size) were prepared from corn stalk soot. ► CNPs-based silica were used as novel chromatography stationary phase. ► The new phase shows good separation selectivity for polar compounds. ► The new phase had the similar retention for polar probes in HILIC and PALC modes. ► In contrast to PALC, under HILIC conditions high efficiencies were achieved. - Abstract: Carbon nanoparticles (CNPs) (6–18 nm in size) were prepared by refluxing corn stalk soot in nitric acid. The obtained acid-oxidized CNPs are soluble in water due to the existence of carboxylic and hydroxyl groups. 13 C NMR measurement shows the CNPs are mainly of sp 2 and sp 3 carbon structure different from CNPs obtained from candle soot and natural gas soot. Furthermore, these CNPs exhibit unique photoluminescence properties. Interestingly, the CNPs might be exploited to immobilize on the surface of porous silica particles as chromatographic stationary phase. The resultant packing material was evaluated by high-performance liquid chromatography, indicating that the new stationary phase could be used in hydrophilic interaction liquid chromatography (HILIC) and per aqueous liquid chromatography (PALC) modes. The separation of five nucleosides, four sulfa compounds and safflower injection was achieved by using the new column in the HILIC and PALC modes, respectively.

Nucleofugalities of Neutral Leaving Groups in 80 % Aqueous Acetonitrile

Directory of Open Access Journals (Sweden)

Sandra Jurić

2016-06-01

Full Text Available Nucleofugalites of tetrahydrothiophene, dimethyl sulfide and differently substituted pyridines in 80 % aqueous acetonitrile have been derived from the SN1 solvolysis rate constants of the corresponding X,Y-substituted benzhydryl derivatives (1–10. In sol-volysis of sulfonium ions in 80 % aqueous acetonitrile, where acetonitrile is a good cation solvator, the solvation of the reactant ground state is an important rate determining variable since the positive charge is almost entirely located on the leaving group. As a consequence, reaction rates of sulfonium ions are more sensitive to the substrate structure in 80 % aqueous acetonitrile than in pure and aqueous alcohols, which are less efficient as cation solvators. In solvolysis of pyridinium ions the solvation of the reactant ground state is less important, since the positive charge is considerably distributed between the carbon at the reaction center and the leaving group. In such cases the important rate determining variable is solvation of the transition state. Slower reactions of pyridinium sub-strates progress over later, carbocation-like transition states in which the solvation is more important, so those substrates solvolyze slightly faster in aqueous acetonitrile than in methanol (k80AN > kM. Faster reactions proceed over earlier TS in which the solvation is diminished, so those substrates solvolyze somewhat faster in methanol than in aqueous acetonitrile (k80AN kM. This work is licensed under a Creative Commons Attribution 4.0 International License.

High temperature aqueous stress corrosion testing device

International Nuclear Information System (INIS)

Bornstein, A.N.; Indig, M.E.

1975-01-01

A description is given of a device for stressing tensile samples contained within a high temperature, high pressure aqueous environment, thereby permitting determination of stress corrosion susceptibility of materials in a simple way. The stressing device couples an external piston to an internal tensile sample via a pull rod, with stresses being applied to the sample by pressurizing the piston. The device contains a fitting/seal arrangement including Teflon and weld seals which allow sealing of the internal system pressure and the external piston pressure. The fitting/seal arrangement allows free movement of the pull rod and the piston

Thermodynamic Characterization of Iron Oxide-Aqueous Fe(2+) Redox Couples.

Science.gov (United States)

Gorski, Christopher A; Edwards, Rebecca; Sander, Michael; Hofstetter, Thomas B; Stewart, Sydney M

2016-08-16

Iron is present in virtually all terrestrial and aquatic environments, where it participates in redox reactions with surrounding metals, organic compounds, contaminants, and microorganisms. The rates and extent of these redox reactions strongly depend on the speciation of the Fe2+ and Fe3+ phases, although the underlying reasons remain unclear. In particular, numerous studies have observed that Fe2+ associated with iron oxide surfaces (i.e., oxide-associated Fe2+) often reduces oxidized contaminants much faster than aqueous Fe2+ alone. Here, we tested two hypotheses related to this observation by determining if solutions containing two commonly studied iron oxides—hematite and goethite—and aqueous Fe2+ reached thermodynamic equilibrium over the course of a day. We measured reduction potential (EH) values in solutions containing these oxides at different pH values and aqueous Fe2+ concentrations using mediated potentiometry. This analysis yielded standard reduction potential (EH0) values of 768 ± 1 mV for the aqueous Fe2+–goethite redox couple and 769 ± 2 mV for the aqueous Fe2+–hematite redox couple. These values were in excellent agreement with those calculated from existing thermodynamic data, and the data could be explained by the presence of an iron oxide lowering EH values of aqueous Fe3+/Fe2+ redox couples.

Direct purification of pectinase from mango (Mangifera Indica Cv. Chokanan) peel using a PEG/salt-based Aqueous Two Phase System.

Science.gov (United States)

Mehrnoush, Amid; Sarker, Md Zaidul Islam; Mustafa, Shuhaimi; Yazid, Abdul Manap Mohd

2011-10-10

An Aqueous Two-Phase System (ATPS) was employed for the first time for the separation and purification of pectinase from mango (Mangifera Indica Cv. Chokanan) peel. The effects of different parameters such as molecular weight of the polymer (polyethylene glycol, 2,000-10,000), potassium phosphate composition (12-20%, w/w), system pH (6-9), and addition of different concentrations of neutral salts (0-8%, w/w) on partition behavior of pectinase were investigated. The partition coefficient of the enzyme was decreased by increasing the PEG molecular weight. Additionally, the phase composition showed a significant effect on purification factor and yield of the enzyme. Optimum conditions for purification of pectinase from mango peel were achieved in a 14% PEG 4000-14% potassium phosphate system using 3% (w/w) NaCl addition at pH 7.0. Based on this system, the purification factor of pectinase was increased to 13.2 with a high yield of (97.6%). Thus, this study proves that ATPS can be an inexpensive and effective method for partitioning of pectinase from mango peel.

Behavior of americium in aqueous carbonate systems

Energy Technology Data Exchange (ETDEWEB)

Silva, R.J.

1983-11-01

The solubilities of crystalline Am(OH)/sub 3/ and AmOHCO/sub 3/ were measured at 25/sup 0/C in aqueous solutions of 0.1 M NaClO/sub 4/ by determination of the solution concentrations of Am. Prior to use in the measurements, the solid materials were characterized by their x-ray powder diffraction patterns. The solubility product quotients were calculated from the experimental data. The hydrolysis quotients of Am/sup 3 +/ were also estimated from the hydroxide solubility data. Using the thermodynamic data derived from these experiments and the recently reported formation constants for the Am/sup 3 +/ carbonate complexes, the solid phases and concentrations of solution species of americium in several aqueous carbonate systems were calculated using the computer code MINEQL. 20 references, 1 figure, 1 table.

Pulsed corona discharge: the role of ozone and hydroxyl radical in aqueous pollutants oxidation.

Science.gov (United States)

Preis, S; Panorel, I C; Kornev, I; Hatakka, H; Kallas, J

2013-01-01

Ozone and hydroxyl radical are the most active oxidizing species in water treated with gas-phase pulsed corona discharge (PCD). The ratio of the species dependent on the gas phase composition and treated water contact surface was the objective for the experimental research undertaken for aqueous phenol (fast reaction) and oxalic acid (slow reaction) solutions. The experiments were carried out in the reactor, where aqueous solutions showered between electrodes were treated with 100-ns pulses of 20 kV voltage and 400 A current amplitude. The role of ozone increased with increasing oxygen concentration and the oxidation reaction rate. The PCD treatment showed energy efficiency surpassing that of conventional ozonation.

Aqueous dispersion of monodisperse magnetic iron oxide nanocrystals through phase transfer

International Nuclear Information System (INIS)

Yu, William W; Chang, Emmanuel; Sayes, Christie M; Drezek, Rebekah; Colvin, Vicki L

2006-01-01

A facile method was developed for completely transferring high quality monodisperse iron oxide nanocrystals from organic solvents to water. The as-prepared aqueous dispersions of iron oxide nanocrystals were extremely stable and could be functionalized for bioconjugation with biomolecules. These iron oxide nanocrystals showed negligible cytotoxicity to human breast cancer cells (SK-BR-3) and human dermal fibroblast cells. This method is general and versatile for many organic solvent-synthesized nanoparticles, including fluorescent semiconductor nanocrystals

Kinetics of silica-phase transitions

International Nuclear Information System (INIS)

Duffy, C.J.

1993-07-01

In addition to the stable silica polymorph quartz, several metastable silica phases are present in Yucca Mountain. The conversion of these phases to quartz is accompanied by volume reduction and a decrease in the aqueous silica activity, which may destabilize clinoptilolite and mordenite. The primary reaction sequence for the silica phases is from opal or glass to disordered opal-CT, followed by ordering of the opal-CT and finally by the crystallization of quartz. The ordering of opal-CT takes place in the solid state, whereas the conversion of opal-CT takes place through dissolution-reprecipitation involving the aqueous phase. It is proposed that the rate of conversion of opal-CT to quartz is controlled by diffusion of defects out of a disordered surface layer formed on the crystallizing quartz. The reaction rates are observed to be dependent on temperature, pressure, degree of supersaturation, and pH. Rate equations selected from the literature appear to be consistent with observations at Yucca Mountain

Purification and characterization of a collagenase from Penicillium sp. UCP 1286 by polyethylene glycol-phosphate aqueous two-phase system.

Science.gov (United States)

de Albuquerque Wanderley, Maria Carolina; Wanderley Duarte Neto, José Manoel; Campos Albuquerque, Wendell Wagner; de Araújo Viana Marques, Daniela; de Albuquerque Lima, Carolina; da Cruz Silvério, Sara Isabel; de Lima Filho, José Luiz; Couto Teixeira, José António; Porto, Ana Lúcia Figueiredo

2017-05-01

Collagenases are proteolytic enzymes capable of degrading both native and denatured collagen, reported to be applied in industrial, medical and biotechnological sectors. Liquid-liquid extraction using aqueous two-phase system (ATPS) is one of the most promising bioseparation techniques, which can substitute difficult solid-liquid separation processes, offering many advantages over conventional methods including low-processing time, low-cost material and low-energy consumption. The collagenase produced by Penicillium sp. UCP 1286 showed a stronger affinity for the bottom salt-rich phase, where the highest levels of collagenolytic activity were observed at the center point runs, using 15.0% (w/w) PEG 3350 g/mol and 12.5% (w/w) phosphate salt at pH 7.0 and concentration. The enzyme was characterized by thermal stability, pH tolerance and effect of inhibitors, showing optimal collagenolytic activity at 37 °C and pH 9.0 and proved to be a serine protease. ATPS showed high efficiency in the collagenase purification, confirmed by a single band in SDS/PAGE, and can in fact be applied as a quick and inexpensive alternative method. Copyright © 2017 Elsevier Inc. All rights reserved.

Determination of butyltin species in natural waters using aqueous phase ethylation and off-line room temperature trapping

International Nuclear Information System (INIS)

Bowles, Karl C.; Apte, Simon C.; Hales, Leigh T.

2003-01-01

Monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) were determined in natural water samples by aqueous phase ethylation with sodium tetraethylborate (STEB), room temperature trapping of the resulting volatile derivatives on Tenax TA[reg], followed by gas chromatography-quartz furnace atomic absorption spectrometry (GC-QFAAS). Recoveries of butyltin spikes from natural water samples were 90-109% at concentrations of ∼100 ng Sn/l. The method precision at ∼100 ng Sn/l was ≤6% RSD for butyltins spiked into natural waters. The detection limits for 1 l water samples were <1 ng Sn/l for all butyltin species. Sample throughput of the method is high (greater than three samples per hour) due to the two-stage nature of the procedure, which allows derivatisation/trapping and GC-QFAAS quantitation to be performed separately. Off-line trapping is also advantageous as it extends the life of the GC column and quartz furnace to at least 12 months due to minimisation of carry-over of co-purged material

Production of gaseous and liquid chemicals by aqueous phase reforming of crude glycerol: Influence of operating conditions on the process

International Nuclear Information System (INIS)

Remón, J.; Giménez, J.R.; Valiente, A.; García, L.; Arauzo, J.

2016-01-01

Highlights: • Aqueous phase reforming: a tailor-made process for the valorisation of crude glycerol. • In-depth understanding of the effect of the operating conditions on the process. • Process optimisation for the selective production of valuable gas and liquid products. • Low pressure and high temperature and spatial time favour gas production. • High pressure and medium temperature maximise the production of valuable liquids. - Abstract: The present work studies the influence of the temperature (200–240 °C), pressure (38–50 bar), glycerol concentration (10–50 wt.%) and mass of catalyst/ glycerol mass flow rate ratio (W/m_g_l_y_c_e_r_o_l = 10–40 g catalyst min/g glycerol) during the aqueous phase reforming (APR) of a glycerol solution obtained from the production of biodiesel. The operating conditions exerted a statistically significant influence on the reforming results. Specifically, the global glycerol conversion and the carbon converted into gas and liquid products varied as follows: 4–100%, 1–80% and 16–93%, respectively. The gas phase was made up of H_2 (8–55 vol.%), CO_2 (34–66 vol.%), CO (0–4 vol.%) and CH_4 (6–45 vol.%). The liquid phase consisted of a mixture of alcohols (monohydric: methanol and ethanol; and polyhydric: 1,2-propanediol, 1,2-ethanediol, 2,3-butanediol), aldehydes (acetaldehyde), ketones (C3-ketones: acetone and 2-propanone-1-hydroxy; C4-ketones: 2-butanone-3-hydroxy and 2-butanone-1-hydroxy; and cyclic ketones), carboxylic acids (acetic and propionic acids) and esters (1,2,3-propanetriol-monoacetate), together with unreacted glycerol and water. The relative amount (free of water and un-reacted glycerol) of these compounds in the liquid phase was as follows: monohydric alcohols: 4–47%, polyhydric-alcohols: 14–68%, aldehydes: 0–5%, C3-ketones: 2–33%, C4-ketones: 0–10%, ciclo-ketones: 0–6%, carboxylic acids: 2–43%, and esters: 0–46%. This process turned out to be highly customisable for the

Human plasma-derived immunoglobulin G fractionated by an aqueous two-phase system, caprylic acid precipitation, and membrane chromatography has a high purity level and is free of detectable in vitro thrombogenic activity.

Science.gov (United States)

Vargas, M; Segura, Á; Wu, Y-W; Herrera, M; Chou, M-L; Villalta, M; León, G; Burnouf, T

2015-02-01

Instituto Clodomiro Picado has developed an immunoglobulin G (IgG) plasma fractionation process combining a polyethylene glycol/phosphate aqueous two-phase system (ATPS), caprylic acid precipitation and anion-exchange membrane chromatography. We evaluated the purity and in vitro thrombogenicity of such IgG, in line with current international requirements. Contributions of the different production steps to reduce thrombogenicity were assessed at 0·2 l-scale, and then the methodology was scaled-up to a 10 l-scale and final products (n = 3) were analysed. Purity, immunoglobulin composition, and subclass distribution were determined by electrophoretic and immunochemical methods. The in vitro thrombogenic potential was determined by a thrombin generation assay (TGA) using a Technothrombin fluorogenic substrate. Prekallikrein activator (PKA), plasmin, factor Xa, thrombin and thrombin-like activities were assessed using S-2302, S-2251, S-2222, S-2238 and S-2288 chromogenic substrates, respectively, and FXI by an ELISA. The thrombogenicity markers were reduced mostly during the ATPS step and were found to segregate mostly into the discarded liquid upper phase. The caprylic acid precipitation eliminated the residual procoagulant activity. The IgG preparations made from the 10 l-batches contained 100% gamma proteins, low residual IgA and undetectable IgM. The IgG subclass distribution was not substantially affected by the process. TGA and amidolytic activities revealed an undetectable in vitro thrombogenic risk and the absence of proteolytic enzymes in the final product. Fractionating human plasma by an ATPS combined with caprylic acid and membrane chromatography resulted in an IgG preparation of high purity and free of a detectable in vitro thrombogenic risk. © 2014 International Society of Blood Transfusion.

Mechanisms leading to oligomers and SOA through aqueous photooxidation: insights from OH radical oxidation of acetic acid and methylglyoxal

Directory of Open Access Journals (Sweden)

Y. Tan

2012-01-01

Full Text Available Previous experiments have demonstrated that the aqueous OH radical oxidation of methylglyoxal produces low volatility products including pyruvate, oxalate and oligomers. These products are found predominantly in the particle phase in the atmosphere, suggesting that methylglyoxal is a precursor of secondary organic aerosol (SOA. Acetic acid plays a central role in the aqueous oxidation of methylglyoxal and it is a ubiquitous product of gas phase photochemistry, making it a potential "aqueous" SOA precursor in its own right. However, the fate of acetic acid upon aqueous-phase oxidation is not well understood. In this research, acetic acid (20 μM–10 mM was oxidized by OH radicals, and pyruvic acid and methylglyoxal experimental samples were analyzed using new analytical methods, in order to better understand the formation of SOA from acetic acid and methylglyoxal. Glyoxylic, glycolic, and oxalic acids formed from acetic acid and OH radicals. In contrast to the aqueous OH radical oxidation of methylglyoxal, the aqueous OH radical oxidation of acetic acid did not produce succinic acid and oligomers. This suggests that the methylgloxal-derived oligomers do not form through the acid catalyzed esterification pathway proposed previously. Using results from these experiments, radical mechanisms responsible for oligomer formation from methylglyoxal oxidation in clouds and wet aerosols are proposed. The importance of acetic acid/acetate as an SOA precursor is also discussed. We hypothesize that this and similar chemistry is central to the daytime formation of oligomers in wet aerosols.

[Determination of ciprofloxacin in human serum and urine by reversed-phase HPLC].

Science.gov (United States)

Qin, Y; Liang, D

1993-03-01

A sensitive and rapid method for the determination of ciprofloxacin using enoxacin as the internal standard was reported. High-performance liquid chromatograph model 344 (Beckman, USA) with a variable wavelength UV detector and reversed-phase Ultrasphere-ODS column (5 microns, 250 x 4.6 mm) was used. Serum or urine sample preparation involved addition phosphate buffer (pH 7.5) and aqueous solution of sodium lauryl sulfate, followed by chloroform extraction. The organic layer was removed and evaporated to dryness under an air stream in a 37 degrees C water bath. The residue was dissolved in 50 microliters mobile phase and 20 microliters injected. The mobile phase of 0.02 mol/L acetate buffer (pH 3.0) -acetonitril-dimethylformamide-10% aqueous solution of tetrabutyl ammonium hydroxide (88:6.5:5:0.5) was pumped at 0.9 ml/min through the column. The detector operated at 0.01 aufs and the wavelength was set at 276 nm. The retention times for ciprofloxacin and enoxacin were 7.31 min and 5.59 min, respectively. In serum, standard curve was linear in the concentration range of 0.75 to 24 mumol/L, the detective limit was 0.2 mumol/L, extraction recovery was 69-74%, within-day CV was less than 5%, and inter-day CV was less than 6%.

Fiber-Optic Chemiluminescent Biosensors for Monitoring Aqueous Alcohols and Other Water Quality Parameters

Science.gov (United States)

Verostko, Charles E. (Inventor); Atwater, James E. (Inventor); Akse, James R. (Inventor); DeHart, Jeffrey L. (Inventor); Wheeler, Richard R. (Inventor)

1998-01-01

A "reagentless" chemiluminescent biosensor and method for the determination of hydrogen peroxide, ethanol and D-glucose in water is disclosed. An aqueous stream is basified by passing it through a solid phase base bed. Luminol is then dissolved in the basified effluent at a controlled rate. Oxidation of the luminol is catalyzed by the target chemical to produce emitted light. The intensity of the emitted light is detected as a measure of the target chemical concentration in the aqueous stream. The emitted light can be transmitted by a fiber optic bundle to a remote location from the aqueous stream for a remote reading of the target chemical concentration.

Mars aqueous chemistry experiment

Science.gov (United States)

Clark, Benton C.; Mason, Larry W.

1994-06-01

Mars Aqueous Chemistry Experiment (MACE) is designed to conduct a variety of measurements on regolith samples, encompassing mineral phase analyses, chemical interactions with H2O, and physical properties determinations. From these data, much can be learned or inferred regarding the past weathering environment, the contemporaneous soil micro-environments, and the general chemical and physical state of the Martian regolith. By analyzing both soil and duricrust samples, the nature of the latter may become more apparent. Sites may be characterized for comparative purposes and criteria could be set for selection of high priority materials on future sample return missions. The second year of the MACE project has shown significant progress in two major areas. MACE Instrument concept definition is a baseline design that has been generated for the complete MACE instrument, including definition of analysis modes, mass estimates and thermal model. The design includes multiple reagent reservoirs, 10 discrete analysis cells, sample manipulation capability, and thermal control. The MACE Measurement subsystems development progress is reported regarding measurement capabilities for aqueous ion sensing, evolved gas sensing, solution conductivity measurement, reagent addition (titration) capabilities, and optical sensing of suspended particles.

Mars aqueous chemistry experiment

Science.gov (United States)

Clark, Benton C.; Mason, Larry W.

1994-01-01

Mars Aqueous Chemistry Experiment (MACE) is designed to conduct a variety of measurements on regolith samples, encompassing mineral phase analyses, chemical interactions with H2O, and physical properties determinations. From these data, much can be learned or inferred regarding the past weathering environment, the contemporaneous soil micro-environments, and the general chemical and physical state of the Martian regolith. By analyzing both soil and duricrust samples, the nature of the latter may become more apparent. Sites may be characterized for comparative purposes and criteria could be set for selection of high priority materials on future sample return missions. The second year of the MACE project has shown significant progress in two major areas. MACE Instrument concept definition is a baseline design that has been generated for the complete MACE instrument, including definition of analysis modes, mass estimates and thermal model. The design includes multiple reagent reservoirs, 10 discrete analysis cells, sample manipulation capability, and thermal control. The MACE Measurement subsystems development progress is reported regarding measurement capabilities for aqueous ion sensing, evolved gas sensing, solution conductivity measurement, reagent addition (titration) capabilities, and optical sensing of suspended particles.

Contributions of nonextracting Pu reductants (ferrous sulphamate and hydroxylamine nitrate) and holding reductant (hydrazine nitrate) to the aqueous density in U-Pu partitioning system

International Nuclear Information System (INIS)

Shekhar Kumar; Rajnish Kumar; Koganti, S.B.

2005-08-01

As nonextracting Pu reductants and holding reductants contribute to the density of aqueous phase sub-system considerably, to account their contributions in aqueous phase in solvent extraction simulation code is essential. In this regard, in-house generated precise density data on aqueous ferrous sulphamate solutions as well as aqueous density data, reported in the literature, for HAN, hydrazine nitrate and HAN-HNO 3 systems were analyzed and density equation earlier proposed by authors was extended to it. It was observed that the equation earlier proposed by the authors were simple and were easy to extend for multicomponent system. The contributions of ferrous sulphamate, HAN and hydrazine nitrate to the aqueous density were quantified. It was also observed that the classical value of contribution for nonextractible solute to the aqueous density was quite different from the results reported in this work. (author)

A Novel Phase-Transformation Activation Process toward Ni-Mn-O Nanoprism Arrays for 2.4 V Ultrahigh-Voltage Aqueous Supercapacitors.

Science.gov (United States)

Zuo, Wenhua; Xie, Chaoyue; Xu, Pan; Li, Yuanyuan; Liu, Jinping

2017-09-01

One of the key challenges of aqueous supercapacitors is the relatively low voltage (0.8-2.0 V), which significantly limits the energy density and feasibility of practical applications of the device. Herein, this study reports a novel Ni-Mn-O solid-solution cathode to widen the supercapacitor device voltage, which can potentially suppress the oxygen evolution reaction and thus be operated stably within a quite wide potential window of 0-1.4 V (vs saturated calomel electrode) after a simple but unique phase-transformation electrochemical activation. The solid-solution structure is designed with an ordered array architecture and in situ nanocarbon modification to promote the charge/mass transfer kinetics. By paring with commercial activated carbon anode, an ultrahigh voltage asymmetric supercapacitor in neutral aqueous LiCl electrolyte is assembled (2.4 V; among the highest for single-cell supercapacitors). Moreover, by using a polyvinyl alcohol (PVA)-LiCl electrolyte, a 2.4 V hydrogel supercapacitor is further developed with an excellent Coulombic efficiency, good rate capability, and remarkable cycle life (>5000 cycles; 95.5% capacity retention). Only one cell can power the light-emitting diode indicator brightly. The resulting maximum volumetric energy density is 4.72 mWh cm -3 , which is much superior to previous thin-film manganese-oxide-based supercapacitors and even battery-supercapacitor hybrid devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Open Circuit Potential Changes upon Protonation/Deprotonation of ω-Functionalized Alkanethiols on Au: Determination of Surface pK {sub 1/2} in Aqueous and Non-Aqueous System

Energy Technology Data Exchange (ETDEWEB)

Yoo, Seung Ryul; Park, Kyung Soon; Jang, Jae Won; Hwang, Seong Pil [Korea Univ., Sejong (Korea, Republic of)

2016-09-15

The controlled assembly of functional nanomaterials has been drawing significant interest for making devices by integration of nanomaterials. The building blocks of functional nanomaterials might be confined spatially on the chemically patterned surface through both covalent and non-covalent bonds. Potentiometric measurement is affordable technique for various researchers because it requires only voltmeter and reference electrode. Moreover, it can be applied to various polar solvent such as methanol and ethanol. The open circuit potential (OCP) is measured indicating the potential difference between reference electrode and working electrode. The potential of working electrode might be affected by redox chemical reaction and charge state/separation. Our results provide the simple and affordable method to investigate pK {sub 1/2} of thin film both in aqueous phase and in non-aqueous phase, which has significant role in colloidal chemistry, nanochemistry, surface chemistry, electrochemistry, and others.

Aqueous biphasic systems involving alkylsulfate-based ionic liquids

Energy Technology Data Exchange (ETDEWEB)

Deive, Francisco J. [Instituto de Tecnologia Quimica e Biologica, UNL, Av. Republica, Apartado 127, 2780-901 Oeiras (Portugal); Department of Chemical Engineering, University of Vigo, P.O. Box 36310, Vigo (Spain); Rodriguez, Ana [Department of Chemical Engineering, University of Vigo, P.O. Box 36310, Vigo (Spain); Marrucho, Isabel M., E-mail: imarrucho@itqb.unl.pt [Instituto de Tecnologia Quimica e Biologica, UNL, Av. Republica, Apartado 127, 2780-901 Oeiras (Portugal); Rebelo, Luis P.N. [Instituto de Tecnologia Quimica e Biologica, UNL, Av. Republica, Apartado 127, 2780-901 Oeiras (Portugal)

2011-11-15

Highlights: > K{sub 3}PO{sub 4}, K{sub 2}CO{sub 3}, Na{sub 2}CO{sub 3}, and (NH{sub 4}){sub 2}SO{sub 4} act as phase promoter in aqueous solutions of ILs. > Remarkable influence of alkyl-chain length on solubility curves of alkylsulfate-based ILs. > Merchuck correlation was used for describing these systems. > {Delta}S{sub hyd} and Hofmeister series were used to discuss the different salting out effects. - Abstract: The specific effects of K{sub 3}PO{sub 4}, K{sub 2}CO{sub 3}, Na{sub 2}CO{sub 3}, and (NH{sub 4}){sub 2}SO{sub 4}, as high charge-density inorganic salts and thus inducers of the formation of aqueous biphasic systems (ABS) containing several ethyl-methylimidazolium alkylsulfate ionic liquids, C{sub 2}MIM C{sub n}SO{sub 4} (n = 2, 4, 6, or 8), have been assessed at T = 298.15 K. The results are analyzed in the light of the Hofmeister series. The influence of different alkyl chain lengths in the anion, together with the ability of the selected inorganic salts to induce the formation of ABS, is discussed. Phase diagrams have been determined through turbidimetry, including tie lines assignments from mass phase ratios according to the lever - arm rule. The Merchuck equation was satisfactorily used to correlate the solubility curve.

Use of two-phase aqueous systems based on water-soluble polymers in thin-layer and extraction chromatography for recovery and separtion of actinides

International Nuclear Information System (INIS)

Molochnikova, N.P.; Shkinev, V.M.; Myasoedov, B.F.

1995-01-01

The feasibility has been demonstrated of using two-phase aqueous systems based on water-soluble polymers, polyethylene glycol and dextran sulfate, in thin-layer and extraction chromatography for recovery and separation of actinides. A convenient method has been proposed for continuous recovery of 239 Np from 243 Am, originating from differences in sorption of tri- and pentavalent actinides from sulfate solutions containing potassium phosphotungstate by silica gel impregnated with polyethylene glycol. New plates for thin-layer chromatography using water-soluble polymers have been developed. These plates were used to study behavior of americium in various oxidation states in thin sorbent layers

Direct NMR Monitoring of Phase Separation Behavior of Highly Supersaturated Nifedipine Solution Stabilized with Hypromellose Derivatives.

Science.gov (United States)

Ueda, Keisuke; Higashi, Kenjirou; Moribe, Kunikazu

2017-07-03

We investigated the phase separation behavior and maintenance mechanism of the supersaturated state of poorly water-soluble nifedipine (NIF) in hypromellose (HPMC) derivative solutions. Highly supersaturated NIF formed NIF-rich nanodroplets through phase separation from aqueous solution containing HPMC derivative. Dissolvable NIF concentration in the bulk water phase was limited by the phase separation of NIF from the aqueous solution. HPMC derivatives stabilized the NIF-rich nanodroplets and maintained the NIF supersaturation with phase-separated NIF for several hours. The size of the NIF-rich phase was different depending on the HPMC derivatives dissolved in aqueous solution, although the droplet size had no correlation with the time for which NIF supersaturation was maintained without NIF crystallization. HPMC acetate and HPMC acetate succinate (HPMC-AS) effectively maintained the NIF supersaturation containing phase-separated NIF compared with HPMC. Furthermore, HPMC-AS stabilized NIF supersaturation more effectively in acidic conditions. Solution 1 H NMR measurements of NIF-supersaturated solution revealed that HPMC derivatives distributed into the NIF-rich phase during the phase separation of NIF from the aqueous solution. The hydrophobicity of HPMC derivative strongly affected its distribution into the NIF-rich phase. Moreover, the distribution of HPMC-AS into the NIF-rich phase was promoted at lower pH due to the lower aqueous solubility of HPMC-AS. The distribution of a large amount of HPMC derivatives into NIF-rich phase induced the strong inhibition of NIF crystallization from the NIF-rich phase. Polymer distribution into the drug-rich phase directly monitored by solution NMR technique can be a useful index for the stabilization efficiency of drug-supersaturated solution containing a drug-rich phase.

Determination of aromatic amines in aqueous extracts of polyurethane foam using hydrophilic interaction liquid chromatography and mass spectrometry

International Nuclear Information System (INIS)

Riddar Johnson, Jakob; Karlsson, Daniel; Dalene, Marianne; Skarping, Gunnar

2010-01-01

A method is presented for the determination of aromatic amines in aqueous extracts of polyurethane (PUR) foam. The method is based on the extraction of PUR foam using aqueous acetic acid (0.1%, w/v) followed by determination of extracted aromatic amines using hydrophilic interaction liquid chromatography (HILIC) and tandem mass spectrometry (MS/MS) with positive electrospray ionisation. The injections of volumes up to 5 μL of aqueous solutions were made possible by on-column focusing with partially filled loop injections. The fragmentation patterns for 2,4- and 2,6-toluene diamine (TDA) and 4,4'-methylene dianiline (MDA) were clarified by performing a hydrogen-deuterium exchange study. TDA and MDA were determined using trideuterated 2,4- and 2,6-TDA and dideuterated 4,4'-MDA as internal standards. Linear calibration graphs were obtained over the range 0.025-0.5 μg mL -1 with correlation coefficients >0.996 and the instrumental detection limit for each compound was <50 fmol. The stability of the amines was influenced by the matrix, so their concentrations decreased over time. Agreement was observed between the results of analyses of PUR foam extracts by HILIC-MS/MS and results obtained by ethyl chloroformate derivatisation and reversed phase (RP) liquid chromatography-mass spectrometry (LC-MS/MS). TDA was observed to be unstable in extracts of foam but not in pure solutions.

Multi-level Quantum Mechanics and Molecular Mechanics Study of Ring Opening Process of Guanine Damage by Hydroxyl Radical in Aqueous Solution.

Science.gov (United States)

Liu, Peng; Wang, Qiong; Niu, Meixing; Wang, Dunyou

2017-08-10

Combining multi-level quantum mechanics theories and molecular mechanics with an explicit water model, we investigated the ring opening process of guanine damage by hydroxyl radical in aqueous solution. The detailed, atomic-level ring-opening mechanism along the reaction pathway was revealed in aqueous solution at the CCSD(T)/MM levels of theory. The potentials of mean force in aqueous solution were calculated at both the DFT/MM and CCSD(T)/MM levels of the theory. Our study found that the aqueous solution has a significant effect on this reaction in solution. In particular, by comparing the geometries of the stationary points between in gas phase and in aqueous solution, we found that the aqueous solution has a tremendous impact on the torsion angles much more than on the bond lengths and bending angles. Our calculated free-energy barrier height 31.6 kcal/mol at the CCSD(T)/MM level of theory agrees well with the one obtained based on gas-phase reaction profile and free energies of solvation. In addition, the reaction path in gas phase was also mapped using multi-level quantum mechanics theories, which shows a reaction barrier at 19.2 kcal/mol at the CCSD(T) level of theory, agreeing very well with a recent ab initio calculation result at 20.8 kcal/mol.

Modeling photodegradation kinetics of three systemic neonicotinoids-dinotefuran, imidacloprid, and thiamethoxam-in aqueous and soil environment.

Science.gov (United States)

Kurwadkar, Sudarshan; Evans, Amanda; DeWinne, Dustan; White, Peter; Mitchell, Forrest

2016-07-01

Environmental presence and retention of commonly used neonicotinoid insecticides such as dinotefuran (DNT), imidacloprid (IMD), and thiamethoxam (THM) are a cause for concern and prevention because of their potential toxicity to nontarget species. In the present study the kinetics of the photodegradation of these insecticides were investigated in water and soil compartments under natural light conditions. The results suggest that these insecticides are fairly unstable in both aqueous and soil environments when exposed to natural sunlight. All 3 insecticides exhibit strong first-order degradation rate kinetics in the aqueous phase, with rate constants kDNT , kIMD , and kTHM of 0.20 h(-1) , 0.30 h(-1) , and 0.18 h(-1) , respectively. However, in the soil phase, the modeled photodegradation kinetics appear to be biphasic, with optimal rate constants k1DNT and k2DNT of 0.0198 h(-1) and 0.0022 h(-1) and k1THM and k2THM of 0.0053 h(-1) and 0.0014 h(-1) , respectively. Differentially, in the soil phase, imidacloprid appears to follow the first-order rate kinetics with a kIMD of 0.0013 h(-1) . These results indicate that all 3 neonicotinoids are photodegradable, with higher degradation rates in aqueous environments relative to soil environments. In addition, soil-encapsulated imidacloprid appears to degrade slowly compared with dinotefuran and thiamethoxam and does not emulate the faster degradation rates observed in the aqueous phase. Environ Toxicol Chem 2016;35:1718-1726. © 2015 SETAC. © 2015 SETAC.

Two-phase ozonation of chlorinated organics

International Nuclear Information System (INIS)

Bhattacharyya, D.; Freshour, A.; West, D.

1995-01-01

In the last few years the amount of research being conducted in the field of single-phase ozonation has grown extensively. However, traditional aqueous-phase ozonation systems are limited by a lack of selective oxidation potential, low ozone solubility in water, and slow intermediate decomposition rates. Furthermore, ozone may decompose before it can be utilized for pollutant destruction since ozone can be highly unstable in aqueous solutions. Naturally occurring compounds such as NaHCO 3 also affect ozone reactions by inhibiting the formation of OH-free radicals. To compensate for these factors, excess ozone is typically supplied to a reactor. Since ozone generation requires considerable electric power consumption (16 - 24 kWh/kg of O 3 ), attempts to enhance the ozone utilization rate and stability should lead to more efficient application of this process to hazardous waste treatment. To improve the process, ozonation may be more efficiently carried out in a two-phase system consisting of an inert solvent (saturated with O 3 ) contacted with an aqueous phase containing pollutants. The non-aqueous phase must meet the following criteria: (1) non-toxic, (2) very low vapor pressure, (3) high density (for ease of separation), (4) complete insolubility in water, (5) reusability, (6) selective pollutant extractability, (7) high oxidant solubility, and (8) extended O 3 stability. Previously published studies (1) have indicated that a number of fluorinated hydrocarbon compounds fit these criteria. For this project, FC40 (a product of 3M Co.) was chosen due to its low vapor pressure (3 mm Hg) and high specific gravity (1.9). The primary advantages of the FC40 solvent are that it is non-toxic, reusable, has an ozone solubility 10 times that of water, and that 85 % of the ozone remains in the solvent even after 2 hours. This novel two-phase process has been utilized to study the rapid destruction of organic chlorine compounds and organic mixtures

The immiscible aqueous solutions of alkyl phosphates. Study for the purpose of uranium extraction from phosphoric acid solutions

International Nuclear Information System (INIS)

Mauborgne, Bernard

1979-01-01

Systems of immiscible aqueous solutions composed by a phase rich in mineral salt and by another phase almost totally containing an organic salt, have been studied for years, with quaternary ammonium salts with an organic cation. The objective of this research is to study systems symmetric to the previous ones, i.e. with organic anions such as alkyl phosphates, and then to try to understand mechanisms of extraction of metals in these environments. Based on properties of immiscible aqueous solutions, an original three-phase process of liquid-liquid extraction has been developed, and is used to separate uranium in phosphoric acids with better performance than the existing industrial processes [fr

Unravelling the Role of an Aqueous Environment on the Electronic Structure and Ionization of Phenol Using Photoelectron Spectroscopy.

Science.gov (United States)

Riley, Jamie W; Wang, Bingxing; Woodhouse, Joanne L; Assmann, Mariana; Worth, Graham A; Fielding, Helen H

2018-02-15

Water is the predominant medium for chemistry and biology, yet its role in determining how molecules respond to ultraviolet light is not well understood at the molecular level. Here, we combine gas-phase and liquid-microjet photoelectron spectroscopy to investigate how an aqueous environment influences the electronic structure and relaxation dynamics of phenol, a ubiquitous motif in many biologically relevant chromophores. The vertical ionization energies of electronically excited states are important quantities that govern the rates of charge-transfer reactions, and, in phenol, the vertical ionization energy of the first electronically excited state is found to be lowered by around 0.8 eV in aqueous solution. The initial relaxation dynamics following photoexcitation with ultraviolet light appear to be remarkably similar in the gas-phase and aqueous solution; however, in aqueous solution, we find evidence to suggest that solvated electrons are formed on an ultrafast time scale following photoexcitation just above the conical intersection between the first two excited electronic states.

Partitioning phase preference for secondary organic aerosol in an urban atmosphere

Science.gov (United States)

Chang, Wayne Li-Wen

Secondary organic aerosol (SOA) comprises a significant portion of atmospheric particular matter (PM). The impact of PM on both human health and global climate has long been recognized. Despite its importance, there are still many unanswered questions regarding the formation and evolution of SOA in the atmosphere. This study uses a modeling approach to understand the preferred partitioning behavior of SOA species into aqueous or organic condensed phases. More specifically, this work uses statistical analyses of approximately 24,000 data values for each variable from a state-of-the-art 3-D airshed model. Spatial and temporal distributions of fractions of SOA residing in the aqueous phase (fAQ) in the South Coast Air Basin of California are presented. Typical values of fAQ within the basin near the surface range from 5 to 80%. Results show that the distribution of fAQ values is inversely proportional to the total SOA loading. Further analysis accounting for various meteorological parameters indicates that large fAQ values are the results of aqueous-phase SOA insensitivity to the ambient conditions; while organic-phase SOA concentrations are dramatically reduced under unfavorable SOA formation conditions, aqueous-phase SOA level remains relatively unchanged, thus increasing fAQ at low SOA loading. Diurnal variations of fAQ near the surface are also observed: it tends to be larger during daytime hours than nighttime hours. When examining the vertical gradient of fAQ, largest values are found at heights above the surface layer. In summary, one must consider SOA in both organic and aqueous phases for proper regional and global SOA budget estimation.

Extraction and recovery of 2-butoxyethanol from aqueous phases containing high saline concentration

Directory of Open Access Journals (Sweden)

Katherine E. Manz

2016-09-01

Full Text Available Ethylene glycol monobutyl ether (EGBE, also known as 2-butoxyethanol (2-BE, has been identified as a contaminant in hydraulic fracturing fluids. In order to determine the presence of 2-BE in hydraulic fracturing chemical additives, a reliable method for recovering 2-BE from aqueous phases by liquid-liquid extraction combined with gas chromatography/mass spectrometry (GC/MS was established. The liquid-liquid extraction method was applied to samples matrices containing various amounts of salt. Using methylene chloride for liquid-liquid extraction in a sample to solvent ratio of 1:3, ≥99% 2-BE recovery may be achieved with less than 5% standard error. The limit of detection was determined to be 0.957 mg L−1 2-BE. Accuracy was determined to be 2.58% and precision was determined using the coefficient of variation, which was 3.5%. The method was used to recover 2-BE in a hydraulic fracturing chemical additive called Revert Flow and to quantify the weight percent of 2-BE in the chemical additive. Weight percent of two additional components of Revert Flow, D-limonene and 1-butoxy-2-propanol, were also determined. We also used the method to determine the abiotic of 2-BE in water, which was 5.55 days. The persistence of 2-BE in hydraulic fracturing fluid was also investigated and determined that 2-BE is more persistent in this environment.

Liquid-liquid transfer phenomena studies coupled with redox reactions: back-extraction of nitrous acid in the presence of scavengers in aqueous phase; Etude de reactions d`oxydoreduction couplees a des phenomenes de transfert liquide-liquide: cas de la desextraction de l`acide nitreux en presence de composes antinitreux en phase aqueuse

Energy Technology Data Exchange (ETDEWEB)

K`zerho, R

1998-12-31

This work deals with the investigation of redox reaction contribution to the kinetics of liquid-liquid transfer, in relation with PUREX reprocessing of spent nuclear fuel. The chemical system chosen concerns the tripping of nitrous acid from tributylphosphate organic phase into a nitric acid aqueous solution containing an `anti-nitrous` component, namely hydrazinium nitrate. According to the abundant literature, a major attention is devoted to the very important role of interfacial phenomena on the kinetics of solvent extraction with tributylphosphate. Although, a suitable experimental technique is chosen, using a constant interfacial area cell of the ARMOLLEX-type. Furthermore, the effects of the hydrodynamical and the physico-chemical parameters on the extraction rate led to the identification of the extraction regime nature: diffusional, then chemical limitation. When no `anti-nitrous` component is used, the diffusional resistance is found to be mainly located in the aqueous diffusion layer. The presence of hydrazinium nitrate into the aqueous solution has an overall accelerating effect on the rate of extraction, related to both a complete suppression of the aqueous diffusional resistance, and a very significant enhancement of the interfacial transfer of the nitrous acid, as a function of hydrazinium concentration. If the first effect could be expected because of the well known fast redox reaction in aqueous phase, the second phenomenon represents a quite original and new result which has never been explored before, to the best of our knowledge. A reaction mechanism is postulated and validated, taking into account the reactive effect of hydrazinium on the interfacial step. In order to support the drawn general patterns, different complementary studies were attempted. When hydroxyl-ammonium nitrate is used, a surprising interfacial transfer blockage is observed, pointing out the extreme performance and specificity of the common hydrazinium component. (author) 99

From cation to oxide: hydroxylation and condensation of aqueous complexes

International Nuclear Information System (INIS)

Jolivet, J.P.

1997-01-01

Hydroxylation, condensation and precipitation of metal cations in aqueous solution are briefly reviewed. Hydroxylation of aqueous complexes essentially depends on the format charge (oxidation state), the size and the pH of the medium. It is the step allowing the condensation reaction. Depending on the nature of complexes (aqua-hydroxo, oxo-hydroxo), the. mechanism of condensation is different, olation or ox-olation respectively. The first one leads to poly-cations or hydroxides more or less stable against dehydration. The second one leads to poly-anions or oxides. Oligomeric species (poly-cations, poly-anions) are form from charged monomer complexes while the formation of solid phases requires non-charged precursors. Because of their high lability, charged oligomers are never the precursors of solids phases. The main routes for the formation of solid phases from solution are studied with two important and representative elements, Al and Si. For Al 3+ ions, different methods (base addition in solution, thermo-hydrolysis, hydrothermal synthesis) are discussed in relation to the crystal structure of the solid phase obtained. For silicic species condensing by ox-olation, the role of acid or base catalysis on the morphology of gels is studied. The influence of complexing ligands on the processes and on the characteristics of solids (morphology of particles, basic salts and polymetallic oxides formation) is studied. (author)

BDD-based reliability evaluation of phased-mission systems with internal/external common-cause failures

International Nuclear Information System (INIS)

Xing, Liudong; Levitin, Gregory

2013-01-01

Phased-mission systems (PMS) are systems in which multiple non-overlapping phases of operations (or tasks) are accomplished in sequence for a successful mission. Examples of PMS abound in applications such as aerospace, nuclear power, and airborne weapon systems. Reliability analysis of a PMS must consider statistical dependence across different phases as well as dynamics in system configuration, failure criteria, and component behavior. This paper proposes a binary decision diagrams (BDD) based method for the reliability evaluation of non-repairable binary-state PMS with common-cause failures (CCF). CCF are simultaneous failure of multiple system elements, which can be caused by some external factors (e.g., lightning strikes, sudden changes in environment) or by propagated failures originating from some elements within the system. Both the external and internal CCF is considered in this paper. The proposed method is combinatorial, exact, and is applicable to PMS with arbitrary system structures and component failure distributions. An example with different CCF scenarios is analyzed to illustrate the application and advantages of the proposed method. -- Highlights: ► Non-repairable phased-mission systems with common-cause failures are analyzed. ► Common-cause failures caused by internal or external factors are considered. ► A combinatorial algorithm based on binary decision diagrams is suggested

High pH mobile phase effects on silica-based reversed-phase high-performance liquid chromatographic columns

NARCIS (Netherlands)

Kirkland, J.J.; Straten, van M.A.; Claessens, H.A.

1995-01-01

Aqueous mobile phases above pH 8 often cause premature column failure, limiting the utility of silica-based columns for applications requiring high pH. Previous studies suggest that covalently bound silane ligands are hydrolyzed and removed by high-pH mobile phases. However, we found that the

Dual Phase Change Thermal Diodes for Enhanced Rectification Ratios: Theory and Experiment

KAUST Repository

Cottrill, Anton L.; Wang, Song; Liu, Albert Tianxiang; Wang, Wen-Jun; Strano, Michael S.

2018-01-01

Thermal diodes are materials that allow for the preferential directional transport of heat and are highly promising devices for energy conservation, energy harvesting, and information processing applications. One form of a thermal diode consists of the junction between a phase change and phase invariant material, with rectification ratios that scale with the square root of the ratio of thermal conductivities of the two phases. In this work, the authors introduce and analyse the concept of a Dual Phase Change Thermal Diode (DPCTD) as the junction of two phase change materials with similar phase boundary temperatures but opposite temperature coefficients of thermal conductivity. Such systems possess a significantly enhanced optimal scaling of the rectification ratio as the square root of the product of the thermal conductivity ratios. Furthermore, the authors experimentally design and fabricate an ambient DPCTD enabled by the junction of an octadecane-impregnated polystyrene foam, polymerized using a high internal phase emulsion template (PFH-O) and a poly(N-isopropylacrylamide) (PNIPAM) aqueous solution. The DPCTD shows a significantly enhanced thermal rectification ratio both experimentally (2.6) and theoretically (2.6) as compared with ideal thermal diodes composed only of the constituent materials.

Dual Phase Change Thermal Diodes for Enhanced Rectification Ratios: Theory and Experiment

KAUST Repository

Cottrill, Anton L.

2018-01-15

Thermal diodes are materials that allow for the preferential directional transport of heat and are highly promising devices for energy conservation, energy harvesting, and information processing applications. One form of a thermal diode consists of the junction between a phase change and phase invariant material, with rectification ratios that scale with the square root of the ratio of thermal conductivities of the two phases. In this work, the authors introduce and analyse the concept of a Dual Phase Change Thermal Diode (DPCTD) as the junction of two phase change materials with similar phase boundary temperatures but opposite temperature coefficients of thermal conductivity. Such systems possess a significantly enhanced optimal scaling of the rectification ratio as the square root of the product of the thermal conductivity ratios. Furthermore, the authors experimentally design and fabricate an ambient DPCTD enabled by the junction of an octadecane-impregnated polystyrene foam, polymerized using a high internal phase emulsion template (PFH-O) and a poly(N-isopropylacrylamide) (PNIPAM) aqueous solution. The DPCTD shows a significantly enhanced thermal rectification ratio both experimentally (2.6) and theoretically (2.6) as compared with ideal thermal diodes composed only of the constituent materials.

Exploring the aqueous vertical ionization of organic molecules by molecular simulation and liquid microjet photoelectron spectroscopy.

Science.gov (United States)

Tentscher, Peter R; Seidel, Robert; Winter, Bernd; Guerard, Jennifer J; Arey, J Samuel

2015-01-08

To study the influence of aqueous solvent on the electronic energy levels of dissolved organic molecules, we conducted liquid microjet photoelectron spectroscopy (PES) measurements of the aqueous vertical ionization energies (VIEaq) of aniline (7.49 eV), veratrole alcohol (7.68 eV), and imidazole (8.51 eV). We also reanalyzed previously reported experimental PES data for phenol, phenolate, thymidine, and protonated imidazolium cation. We then simulated PE spectra by means of QM/MM molecular dynamics and EOM-IP-CCSD calculations with effective fragment potentials, used to describe the aqueous vertical ionization energies for six molecules, including aniline, phenol, veratrole alcohol, imidazole, methoxybenzene, and dimethylsulfide. Experimental and computational data enable us to decompose the VIEaq into elementary processes. For neutral compounds, the shift in VIE upon solvation, ΔVIEaq, was found to range from ≈-0.5 to -0.91 eV. The ΔVIEaq was further explained in terms of the influence of deforming the gas phase solute into its solution phase conformation, the influence of solute hydrogen-bond donor and acceptor interactions with proximate solvent molecules, and the polarization of about 3000 outerlying solvent molecules. Among the neutral compounds, variability in ΔVIEaq appeared largely controlled by differences in solute-solvent hydrogen-bonding interactions. Detailed computational analysis of the flexible molecule veratrole alcohol reveals that the VIE is strongly dependent on molecular conformation in both gas and aqueous phases. Finally, aqueous reorganization energies of the oxidation half-cell ionization reaction were determined from experimental data or estimated from simulation for the six compounds aniline, phenol, phenolate, veratrole alcohol, dimethylsulfide, and methoxybenzene, revealing a surprising constancy of 2.06 to 2.35 eV.

Preparation and evaluation of molecularly imprinted solid-phase micro-extraction fibers for selective extraction of phthalates in an aqueous sample

International Nuclear Information System (INIS)

He Juan; Lv Ruihe; Zhan Haijun; Wang Huizhi; Cheng Jie; Lu Kui; Wang Fengcheng

2010-01-01

A novel molecularly imprinted polymer (MIP) that was applied to a solid-phase micro-extraction (SPME) device, which could be coupled directly to gas chromatograph and mass spectrometer (GC/MS), was prepared using dibutyl phthalate (DBP) as the template molecule. The characteristics and application of this fiber were investigated. Electron microscope images indicated that the MIP-coated solid-phase micro-extraction (MI-SPME) fibers were homogeneous and porous. The extraction yield of DBP with the MI-SPME fibers was higher than that of the non-imprinted polymer (NIP)-coated SPME (NI-SPME) fibers. The MI-SPME fibers had a higher selectivity to other phthalates that had similar structures as DBP. A method was developed for the determination of phthalates using MI-SPME fibers coupled with GC/MS. The extraction conditions were optimized. Detection limits for the phthalate samples were within the range of 2.17-20.84 ng L -1 . The method was applied to five kinds of phthalates dissolved in spiked aqueous samples and resulted in recoveries of up to 94.54-105.34%, respectively. Thus, the MI-SPME fibers are suitable for the extraction of trace phthalates in complicated samples.

Aerosol Particle Interfacial Thermodynamics and Phase Partitioning Measurements Using Biphasic Microfluidics

Science.gov (United States)

Dutcher, Cari; Metcalf, Andrew

2015-03-01

Secondary organic aerosol particles are nearly ubiquitous in the atmosphere and yet there remain large uncertainties in their formation processes and ambient properties. These particles are complex microenvironments, which can contain multiple interfaces due to internal aqueous-organic phase partitioning and to the external liquid-vapor surface. Interfacial properties affect the ambient aerosol morphology, or internal structure of the particle, which in turn can affect the way a particle interacts with an environment of condensable clusters and organic vapors. To improve our ability to accurately predict ambient aerosol morphology, we must improve our knowledge of aerosol interfaces and their interactions with the ambient environment. Unfortunately, many techniques employed to measure interfacial properties do so in bulk solutions or in the presence of a ternary (e.g. solid) phase. In this talk, a novel method using biphasic microscale flows will be introduced for generating, trapping, and perturbing complex interfaces at atmospherically relevant conditions. These microfluidic experiments utilize high-speed imaging to monitor interfacial phenomena at the microscale and are performed with phase contrast and fluorescence microscopy on a temperature-controlled inverted microscope stage. From these experiments, interfacial thermodynamic properties such as surface or interfacial tension, rheological properties such as interfacial moduli, and kinetic properties such as mass transfer coefficients can be measured or inferred.

Aqueous-stream uranium-removal technology cost/benefit and market analysis

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-03-01

The primary purpose of this report is to present information that was gathered by Kapline Enterprises, Inc. (KEI) in order to help the Department of Energy (DOE) determine the merit of continued biosorption research funding. However, in the event that funding is continued, it is also intended to help the researchers in their efforts to develop a better uranium-removal process. This report (1) provides a comparison of DOE sites that may utilize aqueous-stream, uranium-removal biosorption technology, (2) presents a comparison of the biosorption and ion exchange processes, and (3) establishes performance criteria by which the project can be measured. It also attempts to provide focus for biosorbent ground-water-remediation research and to ask questions that need to be answered. This report is primarily a study of the US market for technologies that remove uranium from aqueous streams, but it also addresses the international market-particularly for Germany. Because KEI`s access to international market information is extremely limited, the material presented in this report represents a best effort to obtain this data. Although uranium-contaminated aqueous streams are a problem in other countries as well, the scope of this report is primarily limited to the US and Germany for two reasons: (1) Germany is the country of the biosorbent-CRADA partner and (2) time constraints.

Aqueous-stream uranium-removal technology cost/benefit and market analysis

International Nuclear Information System (INIS)

1994-03-01

The primary purpose of this report is to present information that was gathered by Kapline Enterprises, Inc. (KEI) in order to help the Department of Energy (DOE) determine the merit of continued biosorption research funding. However, in the event that funding is continued, it is also intended to help the researchers in their efforts to develop a better uranium-removal process. This report (1) provides a comparison of DOE sites that may utilize aqueous-stream, uranium-removal biosorption technology, (2) presents a comparison of the biosorption and ion exchange processes, and (3) establishes performance criteria by which the project can be measured. It also attempts to provide focus for biosorbent ground-water-remediation research and to ask questions that need to be answered. This report is primarily a study of the US market for technologies that remove uranium from aqueous streams, but it also addresses the international market-particularly for Germany. Because KEI's access to international market information is extremely limited, the material presented in this report represents a best effort to obtain this data. Although uranium-contaminated aqueous streams are a problem in other countries as well, the scope of this report is primarily limited to the US and Germany for two reasons: (1) Germany is the country of the biosorbent-CRADA partner and (2) time constraints

Aqueous solubility, dispersibility and toxicity of biodiesels

International Nuclear Information System (INIS)

Hollebone, B.P.; Fieldhouse, B.; Lumley, T.C.; Landriault, M.; Doe, K.; Jackman, P.

2007-01-01

The renewed interest in the use of biological fuels can be attributed to that fact that feedstocks for fatty-acid ester biodiesels are renewable and can be reclaimed from waste. Although there are significant benefits to using biodiesels, their increased use leaves potential for accidental release to the environment. Therefore, their environmental behaviours and impacts must be evaluated along with the risk associated with their use. Biodiesel fuels may be made from soy oil, canola oil, reclaimed restaurant grease, fish oil and animal fat. The toxicological fate of biofuel depends on the variability of its chemical composition. This study provided an initial assessment of the aqueous fate and effects of biodiesel from a broad range of commonly available feedstocks and their blends with petroleum diesels. The study focused primarily on the fate and impact of these fuels in fresh-water. The use of chemical dispersion as a countermeasure for saltwater was also investigated. The exposure of aquatic ecosystems to biodiesels and petroleum diesel occurs via the transfer of material from the non-aqueous phase liquid (NAPL) into the aqueous phase, as both soluble and dispersed components. The aqueous solubilities of the fuels were determined from the equilibrium water-accommodated fraction concentrations. The acute toxicities of many biodiesels were reported for 3 test species used by Environment Canada for toxicological evaluation, namely rainbow trout, the water flea and a luminescent bacterium. This study also evaluated the natural potential for dispersion of the fuels in the water column in both low and high-energy wave conditions. Chemical dispersion as a potential countermeasure for biodiesel spills was also evaluated using solubility testing, acute toxicity testing, and dispersibility testing. It was shown that biodiesels have much different fates and impacts from petroleum diesels. The compounds partitioning into the water column are also very different for each

Formation of uniform carrot-like Cu31S16-CuInS2 heteronanostructures assisted by citric acid at the oil/aqueous interface.

Science.gov (United States)

Li, Yongjie; Tang, Aiwei; Liu, Zhenyang; Peng, Lan; Yuan, Yi; Shi, Xifeng; Yang, Chunhe; Teng, Feng

2018-01-07

A simple two-phase strategy was developed to prepare Cu 31 S 16 -CuInS 2 heterostructures (HNS) at the oil/aqueous interface, in which the In(OH) 3 phase was often obtained in the products due to the reaction between indium ions and hydroxyl ions in the aqueous phase. To prevent the formation of the In(OH) 3 phase, citric acid was incorporated into the aqueous phase to assist in the synthesis of uniform carrot-like Cu 31 S 16 -CuInS 2 semiconductor HNS at the oil/aqueous interface for the first time. By manipulating the dosage of citric acid and Cu/In precursor ratios, the morphology of the Cu 31 S 16 -CuInS 2 HNS could be tailored from mushroom to carrot-like, and the presence of citric acid played a critical role in the synthesis of high-quality Cu 31 S 16 -CuInS 2 HNS, which inhibited the formation of the In(OH) 3 phase due to the formation of the indium(iii)-citric acid complex. The formation mechanism was studied by monitoring the morphology and phase evolution of the Cu 31 S 16 -CuInS 2 HNS with reaction time, which revealed that the Cu 31 S 16 seeds were first formed and then the cation-exchange reaction directed the subsequent anisotropic growth of the Cu 31 S 16 -CuInS 2 HNS.

Quantification of amino acids and peptides in an ionic liquid based aqueous two-phase system by LC-MS analysis.

Science.gov (United States)

Oppermann, Sebastian; Oppermann, Christina; Böhm, Miriam; Kühl, Toni; Imhof, Diana; Kragl, Udo

2018-04-25

Aqueous two-phase systems (ATPS) occur by the mixture of two polymers or a polymer and an inorganic salt in water. It was shown that not only polymers but also ionic liquids in combination with inorganic cosmotrophic salts are able to build ATPS. Suitable for the formation of ionic liquid-based ATPS systems are hydrophilic water miscible ionic liquids. To understand the driving force for amino acid and peptide distribution in IL-ATPS at different pH values, the ionic liquid Ammoeng 110™ and K 2 HPO 4 have been chosen as a test system. To quantify the concentration of amino acids and peptides in the different phases, liquid chromatography and mass spectrometry (LC-MS) technologies were used. Therefore the peptides and amino acids have been processed with EZ:faast™-Kit from Phenomenex for an easy and reliable quantification method even in complex sample matrices. Partitioning is a surface-dependent phenomenon, investigations were focused on surface-related amino acid respectively peptide properties such as charge and hydrophobicity. Only a very low dependence between the amino acids or peptides hydrophobicity and the partition coefficient was found. Nevertheless, the presented results show that electrostatic respectively ionic interactions between the ionic liquid and the amino acids or peptides have a strong impact on their partitioning behavior.

Valorisation of Vietnamese Rice Straw Waste: Catalytic Aqueous Phase Reforming of Hydrolysate from Steam Explosion to Platform Chemicals

Directory of Open Access Journals (Sweden)

Cao Huong Giang

2014-12-01

Full Text Available A family of tungstated zirconia solid acid catalysts were synthesised via wet impregnation and subsequent thermochemical processing for the transformation of glucose to 5-hydroxymethylfurfural (HMF. Acid strength increased with tungsten loading and calcination temperature, associated with stabilisation of tetragonal zirconia. High tungsten dispersions of between 2 and 7 W atoms·nm−2 were obtained in all cases, equating to sub-monolayer coverages. Glucose isomerisation and subsequent dehydration via fructose to HMF increased with W loading and calcination temperature up to 600 °C, indicating that glucose conversion to fructose was favoured over weak Lewis acid and/or base sites associated with the zirconia support, while fructose dehydration and HMF formation was favoured over Brönsted acidic WOx clusters. Aqueous phase reforming of steam exploded rice straw hydrolysate and condensate was explored heterogeneously for the first time over a 10 wt% WZ catalyst, resulting in excellent HMF yields as high as 15% under mild reaction conditions.

Analysis of a microscale 'Saturation Phase-change Internal Carnot Engine'

International Nuclear Information System (INIS)

Lurie, Eli; Kribus, Abraham

2010-01-01

A micro heat engine, based on a cavity filled with a stationary working fluid under liquid-vapor saturation conditions and encapsulated by two membranes, is described and analyzed. This engine design is easy to produce using MEMS technologies and is operated with external heating and cooling. The motion of the membranes is controlled such that the internal pressure and temperature are constant during the heat addition and removal processes, and thus the fluid executes a true internal Carnot cycle. A model of this Saturation Phase-change Internal Carnot Engine (SPICE) was developed including thermodynamic, mechanical and heat transfer aspects. The efficiency and maximum power of the engine are derived. The maximum power point is fixed in a three-parameter space, and operation at this point leads to maximum power density that scales with the inverse square of the engine dimension. Inclusion of the finite heat capacity of the engine wall leads to a strong dependence of performance on engine frequency, and the existence of an optimal frequency. Effects of transient reverse heat flow, and 'parasitic heat' that does not participate in the thermodynamic cycle are observed.

Plume Migration of Different Carbon Dioxide Phases During Geological Storage in Deep Saline Aquifers

Directory of Open Access Journals (Sweden)

Chien-Hao Shen

2015-01-01

Full Text Available This study estimates the plume migration of mobile supercritical phase (flowing, aqueous phase (dissolved, and ionic phase CO2 (bicarbonate, and evaluates the spatial distribution of immobile supercritical phase (residual and mineral phase CO2 (carbonates when CO2 was sequestered. This utilized a simulation, in an anticline structure of a deep saline aquifer in the Tiechenshan (TCS field, Taiwan. All of the trapping mechanisms and different CO2 phases were studied using the fully coupled geochemical equation-of-state GEM compositional simulator. The mobile supercritical phase CO2 moved upward and then accumulated in the up-dip of the structure because of buoyancy. A large amount of immobile supercritical phase CO2 was formed at the rear of the moving plume where the imbibition process prevailed. Both the aqueous and ionic phase CO2 finally accumulated in the down-dip of the structure because of convection. The plume volume of aqueous phase CO2 was larger than that of the supercritical phase CO2, because the convection process increased vertical sweep efficiency. The up-dip of the structure was not the major location for mineralization, which is different from mobile supercritical phase CO2 accumulation.

Measurement of underground contamination of non-aqueous phase liquids (NAPLs) on the basis of the radon concentration in ground level air

International Nuclear Information System (INIS)

Schubert, M.

2001-01-01

It was investigated whether measurements of radon concentrations in ground level air are a suitable method of detecting sub-surface soil contamination with non-aqueous phase liquids (NAPLs). The working postulation was that, due to the very high solubility of radon in NAPLs, and the resulting accumulation of radon in NAPLs, radon exhalation to the ground level air in the proximity of such NAPL contamination should be locally reduced, thus indicating contamination of sub-surface soils with NAPLs. The research work reported was to verify the working theory by way of experiments, and to finally develop a reliable detection method for NAPL contaminations. The investigations comprised theoretical studies, laboratory experiments, experiments in defined soil columns, and extensive field studies [de

Enzyme Stability and Activity in Non-Aqueous Reaction Systems: A Mini Review

Directory of Open Access Journals (Sweden)

Shihui Wang

2016-02-01

Full Text Available Enormous interest in biocatalysis in non-aqueous phase has recently been triggered due to the merits of good enantioselectivity, reverse thermodynamic equilibrium, and no water-dependent side reactions. It has been demonstrated that enzyme has high activity and stability in non-aqueous media, and the variation of enzyme activity is attributed to its conformational modifications. This review comprehensively addresses the stability and activity of the intact enzymes in various non-aqueous systems, such as organic solvents, ionic liquids, sub-/super-critical fluids and their combined mixtures. It has been revealed that critical factors such as Log P, functional groups and the molecular structures of the solvents define the microenvironment surrounding the enzyme molecule and affect enzyme tertiary and secondary structure, influencing enzyme catalytic properties. Therefore, it is of high importance for biocatalysis in non-aqueous media to elucidate the links between the microenvironment surrounding enzyme surface and its stability and activity. In fact, a better understanding of the correlation between different non-aqueous environments and enzyme structure, stability and activity can contribute to identifying the most suitable reaction medium for a given biotransformation.

An alternative method to isolate protease and phospholipase A2 toxins from snake venoms based on partitioning of aqueous two-phase systems

Directory of Open Access Journals (Sweden)

GN Gómez

2012-01-01

Full Text Available Snake venoms are rich sources of active proteins that have been employed in the diagnosis and treatment of health disorders and antivenom therapy. Developing countries demand fast economical downstream processes for the purification of this biomolecule type without requiring sophisticated equipment. We developed an alternative, simple and easy to scale-up method, able to purify simultaneously protease and phospholipase A2 toxins from Bothrops alternatus venom. It comprises a multiple-step partition procedure with polyethylene-glycol/phosphate aqueous two-phase systems followed by a gel filtration chromatographic step. Two single bands in SDS-polyacrylamide gel electrophoresis and increased proteolytic and phospholipase A2 specific activities evidence the homogeneity of the isolated proteins.

Radiation degradation of waste waters. Reverse phase-high performance liquid chromatography and multicomponent UV-VIS analysis of gamma-irradiated aqueous solutions of nitrobenzene Pt.1

International Nuclear Information System (INIS)

Kuruc, J.; Sahoo, M.K.; Locaj, J.; Hutta, M.

1994-01-01

Saturated aqueous solutions of nitrobenzene (in water, 0.1M nitric acid and 0.1M potassium hydroxide) were irradiated with 60 Co γ-rays in deaerated condition. Radiolytic products were analyzed using reverse phase-high performance liquid chromatography (RP-HPLC) and multicomponent UV-VIS spectrometry. With the aid of RP-HPLC retention times of the radiolytic products were found to be identical with those of isomeric nitrophenols, aminophenols and dinitrophenols. According to the primary information obtained from RP-HPLC and literature, we have chosen ten standards and eleven wavelengths for multicomponent UV-VIS analysis (linear multiparametric regression analysis) and the concentrations of nitrobenzene, nitrophenols, aminophenols and dinitrophenols in water, HNO 3 and KOH solutions were calculated. G-values (molecules/100 eV) of the radiolytic products and decomposition of nitrobenzene in aqueous solutions G(-nitrobenzene) were calculated from the dependence of their concentrations with dose. Ph has relatively little influence on the decrease of concentration of nitrobenzene, but has strong influence on the product composition. (author) 7 refs.; 5 figs.; 5 tabs

Molecular dynamics simulation of cyclodextrin aggregation and extraction of Anthracene from non-aqueous liquid phase

Energy Technology Data Exchange (ETDEWEB)

Zhu, Xinzhe [Shenzhen Key Laboratory for Coastal Ocean Dynamic and Environment, Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); School of Environment, Tsinghua University, Beijing 100084 (China); Wu, Guozhong [Shenzhen Key Laboratory for Coastal Ocean Dynamic and Environment, Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Chen, Daoyi, E-mail: chen.daoyi@sz.tsinghua.edu.cn [Shenzhen Key Laboratory for Coastal Ocean Dynamic and Environment, Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China)

2016-12-15

Cyclodextrin (CD) extraction is widely used for the remediation of polycyclic aromatic hydrocarbons (PAH) pollution, but it remains unclear about the influence of CD aggregation on the PAH transport from non-aqueous liquid phase to water. The atomistic adsorption and complexation of PAHs (32 anthracenes) by CD aggregates (48 β-cyclodextrins) were studied by molecular dynamics simulations at hundreds of nanoseconds time scale. Results indicated that high temperature promoted the βCD aggregation in bulk oil, which was not found in bulk water. Nevertheless, the fractions of anthracenes entrapped inside the βCDs cavity in both scenarios were significantly increased when temperature increased from 298 to 328 K. Free energy calculation for the sub-steps of CD extraction demonstrated that the anthracenes could be extracted when the βCDs arrived at the water-oil interface or after the βCDs entered the bulk oil. The former was kinetic-controlled while the latter was thermodynamic-limited process. Results also highlighted the formation of porous structures by CD aggregates in water, which was able to sequestrate PAH clusters with the size obviously larger than the cavity diameter of individual CD. This provided an opportunity for the extraction of recalcitrant PAHs with molecular size larger than anthracenes by cyclodextrins.

Aqueous phase hydrogenation of phenol catalyzed by Pd and PdAg on ZrO 2

Energy Technology Data Exchange (ETDEWEB)

Resende, Karen A.; Hori, Carla E.; Noronha, Fabio B.; Shi, Hui; Gutierrez, Oliver Y.; Camaioni, Donald M.; Lercher, Johannes A.

2017-11-01

Hydrogenation of phenol in aqueous phase was studied over a series of ZrO2-supported Pd catalysts in order to explore the effects of particle size and of Ag addition on the activity of Pd. Kinetic assessments were performed in a batch reactor, on monometallic Pd/ZrO2 samples with different Pd loadings (0.5%, 1% and 2%), as well as on a 1% PdAg/ZrO2 sample. The turnover frequency (TOF) increases with the Pd particle size. The reaction orders in phenol and H2 indicate that the surface coverages by phenol, H2 and their derived intermediates are higher on 0.5% Pd/ZrO2 than on other samples. The activation energy was the lowest on the least active sample (0.5% Pd/ZrO2), while being identical on 1% and 2% Pd/ZrO2 catalysts. Thus, the significantly lower activity of the small Pd particles (1-2 nm on average) in 0.5%Pd/ZrO2 is explained by the unfavorable activation entropies for the strongly bound species. The presence of Ag increases considerably the TOF of the reaction by decreasing the Ea and increasing the coverages of phenol and H2.

Using an aqueous two-phase polymer-salt system to rapidly concentrate viruses for improving the detection limit of the lateral-flow immunoassay.

Science.gov (United States)

Jue, Erik; Yamanishi, Cameron D; Chiu, Ricky Y T; Wu, Benjamin M; Kamei, Daniel T

2014-12-01

The development of point-of-need (PON) diagnostics for viruses has the potential to prevent pandemics and protects against biological warfare threats. Here we discuss the approach of using aqueous two-phase systems (ATPSs) to concentrate biomolecules prior to the lateral-flow immunoassay (LFA) for improved viral detection. In this paper, we developed a rapid PON detection assay as an extension to our previous proof-of-concept studies which used a micellar ATPS. We present our investigation of a more rapid polymer-salt ATPS that can drastically improve the assay time, and show that the phase containing the concentrated biomolecule can be extracted prior to macroscopic phase separation equilibrium without affecting the measured biomolecule concentration in that phase. We could therefore significantly decrease the time of the diagnostic assay with an early extraction time of just 30 min. Using this rapid ATPS, the model virus bacteriophage M13 was concentrated between approximately 2 and 10-fold by altering the volume ratio between the two phases. As the extracted virus-rich phase contained a high salt concentration which destabilized the colloidal gold indicator used in LFA, we decorated the gold nanoprobes with polyethylene glycol (PEG) to provide steric stabilization, and used these nanoprobes to demonstrate a 10-fold improvement in the LFA detection limit. Lastly, a MATLAB script was used to quantify the LFA results with and without the pre-concentration step. This approach of combining a rapid ATPS with LFA has great potential for PON applications, especially as greater concentration-fold improvements can be achieved by further varying the volume ratio. Biotechnol. Bioeng. 2014;111: 2499-2507. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.

A method for the preparation of curcumin by ultrasonic-assisted ammonium sulfate/ethanol aqueous two phase extraction.

Science.gov (United States)

Xu, Guangkuan; Hao, Changchun; Tian, Suyang; Gao, Feng; Sun, Wenyuan; Sun, Runguang

2017-01-15

This study investigated a new and easy-to-industrialized extracting method for curcumin from Curcuma longa rhizomes using ultrasonic extraction technology combined with ammonium sulfate/ethanol aqueous two-phase system (ATPS), and the preparation of curcumin using the semi-preparative HPLC. The single-factor experiments and response surface methodology (RSM) were utilized to determine the optimal material-solvent ratio, ultrasonic intensity (UI) and ultrasonic time. The optimum extraction conditions were finally determined to be material-solvent rate of 3.29:100, ultrasonic intensity of 33.63W/cm 2 and ultrasonic time of 17min. At these optimum conditions, the extraction yield could reach 46.91mg/g. And the extraction yields of curcumin remained stable in the case of amplification, which indicated that scale-up extraction was feasible and efficient. Afterwards, the semi-preparative HPLC experiment was carried out, in which optimal preparation conditions were elected according to the single factor experiment. The prepared curcumin was obtained and the purity could up to 85.58% by the semi-preparative HPLC. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of gamma radiation on phase behaviour and critical micelle concentration of Triton X-100 aqueous solutions

International Nuclear Information System (INIS)

Valdes Diaz, G.; Rodriguez-Calvo, S.; Perez-Gramatges, A.; Rapado-Paneque, M.; Fernandez-Lima, F. A.; Ponciano, C. R.; Silveira, E. F. . E-mail. apgram@instec.cu

2007-01-01

Ionising radiation used for sterilisation can have an effect on the physico-chemical properties of pharmaceutically relevant excipient systems, affecting therefore the stability of the formulation. The effect of gamma irradiation on the phase behaviour (cloud point - CP) and critical micelle concentration (CMC) of aqueous solutions of Triton X-100, used as a model nonionic surfactant, is investigated in this paper. Micellar solutions irradiated with ?-rays in a dose range between 0 and 70 kGy, including the sterilisation range of pharmaceutical preparations, were analysed using mass spectrometry. Results show a slight shift in molecular mass distribution of ethoxylated surfactant, which indicates degradation of polyethoxylated chains by water radical attacks. This fact, combined with the formation of cross-linked species, is considered to be responsible for the decrease observed in CP and CMC values of micellar solutions at all absorbed doses. There is no spectroscopic evidence of radiation damage to aromatic ring or hydrocarbon tail of surfactant. Models based on Flory-Huggins theory were employed to estimate CP from changes in mass distribution and to obtain cross-linking fractions. (Author)

Expanded separation technique for chlorophyll metabolites in Oriental tobacco leaf using non aqueous reversed phase chromatography.

Science.gov (United States)

Ishida, Naoyuki

2011-08-26

An improved separation method for chlorophyll metabolites in Oriental tobacco leaf was developed. While Oriental leaf still gives the green color even after the curing process, little attention has been paid to the detailed composition of the remaining green pigments. This study aimed to identify the green pigments using non aqueous reversed phase chromatography (NARPC). To this end, liquid chromatograph (LC) equipped with a photo diode array detector (DAD) and an atmospheric pressure chemical ionization/mass spectrometer (APCI/MSD) was selected, because it is useful for detecting low polar non-volatile compounds giving green color such as pheophytin a. Identification was based on the wavelength spectrum, mass spectrum and retention time, comparing the analytes in Oriental leaf with the commercially available and synthesized components. Consequently, several chlorophyll metabolites such as hydroxypheophytin a, solanesyl pheophorbide a and solanesyl hydroxypheophorbide a were newly identified, in addition to typical green pigments such as chlorophyll a and pheophytin a. Chlorophyll metabolites bound to solanesol were considered the tobacco specific components. NARPC expanded the number of detectable low polar chlorophyll metabolites in Oriental tobacco leaf. Copyright © 2011 Elsevier B.V. All rights reserved.

Soft matter at aqueous interfaces

CERN Document Server

Liu, Yi

2016-01-01

This book covers the science of interfaces between an aqueous phase and a solid, another liquid or a gaseous phase, starting from the basic physical chemistry all the way to state-of-the-art research developments. Both experimental and theoretical methods are treated thanks to the contributions of a distinguished list of authors who are all active researchers in their respective fields. The properties of these interfaces are crucial for a wide variety of processes, products and biological systems and functions, such as the formulation of personal care and food products, paints and coatings, microfluidic and lab-on-a-chip applications, cell membranes, and lung surfactants. Accordingly, research and expertise on the subject are spread over a broad range of academic disciplines and industrial laboratories. This book brings together knowledge from these different places with the aim of fostering education, collaborations and research progress.

Influence of Calcium on Microbial Reduction of Solid Phase Uranium (VI)

International Nuclear Information System (INIS)

Liu, Chongxuan; Jeon, Byong-Hun; Zachara, John M.; Wang, Zheming

2007-01-01

The effect of calcium on microbial reduction of a solid phase U(VI), sodium boltwoodite (NaUO2SiO3OH · 1.5H2O), was evaluated in a culture of a dissimilatory metal-reducing bacterium (DMRB), Shewanella oneidensis strain MR-1. Batch experiments were performed in a non-growth bicarbonate medium with lactate as electron donor at pH 7 buffered with PIPES. Calcium increased both the rate and extent of Na-boltwoodite dissolution by increasing its solubility through the formation of a ternary aqueous calcium-uranyl-carbonate species. The ternary species, however, decreased the rates of microbial reduction of aqueous U(VI). Laser-induced fluorescence spectroscopy (LIFS) and transmission electron microscopy (TEM) revealed that microbial reduction of solid phase U(VI) is a sequentially coupled process of Na-boltwoodite dissolution, U(VI) aqueous speciation, and microbial reduction of dissolved U(VI) to U(IV) that accumulated on bacterial surfaces/periplasm. The overall rates of microbial reduction of solid phase U(VI) can be described by the coupled rates of dissolution and microbial reduction that were both influenced by calcium. The results demonstrated that dissolved U(VI) concentration during microbial reduction was a complex function of solid phase U(VI) dissolution kinetics, aqueous U(VI) speciation, and microbial activity

Carbohydrates-tailored phase tunable systems composed of ionic liquids and water

International Nuclear Information System (INIS)

Chen Yuhaun; Wang Yige; Cheng Qingyan; Liu Xiaoli; Zhang Suojiang

2009-01-01

Carbohydrates were found to have substantial effects on tailoring phase tunable of ionic liquids (ILs) and water. Phase behaviors of 1-alkyl-3-methylimidazolium derivatives [C n mim]X (n = 2 to 10, X = Cl - , Br - , BF 4 - )-carbohydrate-H 2 O were systemically investigated. For hydrophilic ILs, 1-alkyl-3-methylimidazolium tetrafluoroborate [C n mim]BF 4 (n = 3, 4), the homogeneous aqueous solution can be induced to separate two aqueous phases by addition of carbohydrate. For hydrophobic ILs, [C n mim]BF 4 (n = 5 to 10), the mutual solubility with water can be lowered by addition of carbohydrate. While 1-alkyl-3-methyl imidazolium chloride ([C n mim]Cl, n = 2 to 10) and 1-alkyl-3-methyl imidazolium bromide ([C n mim]Br, n = 2 to 10) aqueous solutions never form aqueous two-phase systems (ATPSs) with carbohydrate in the investigated temperatures ranging from (242.15 to 373.15) K. The high partitioning behavior of phenol in [C n mim]BF 4 (n = 3 to 10) (1) + carbohydrate (2) + H 2 O (3) shows that carbohydrate-tailored {IL + H 2 O} systems are feasible to be used as extraction systems, especially in biological and environmental engineering.

Flow of Aqueous Humor

Science.gov (United States)

... Home Flow of Aqueous Humor Flow of Aqueous Humor Most, but not all, forms of glaucoma are ... remains normal when some of the fluid (aqueous humor) produced by the eye's ciliary body flows out ...

Inter-laboratory exercise on steroid estrogens in aqueous samples

International Nuclear Information System (INIS)

Heath, E.; Kosjek, T.; Andersen, H.R.; Holten Luetzhoft, H.-C.; Adolfson Erici, M.; Coquery, M.; Duering, R.-A.; Gans, O.; Guignard, C.; Karlsson, P.; Manciot, F.; Moldovan, Z.; Patureau, D.; Cruceru, L.; Sacher, F.; Ledin, A.

2010-01-01

An inter-laboratory comparison exercise was organized among European laboratories, under the aegis of EU COST Action 636: 'Xenobiotics in Urban Water Cycle'. The objective was to evaluate the performance of testing laboratories determining 'Endocrine Disrupting Compounds' (EDC) in various aqueous matrices. As the main task three steroid estrogens: 17α-ethinylestradiol, 17β-estradiol and estrone were determined in four spiked aqueous matrices: tap water, river water and wastewater treatment plant influent and effluent using GC-MS and LC-MS/MS. Results were compared and discussed according to the analytical techniques applied, the accuracy and reproducibility of the analytical methods and the nature of the sample matrices. Overall, the results obtained in this inter-laboratory exercise reveal a high level of competence among the participating laboratories for the detection of steroid estrogens in water samples indicating that GC-MS as well as LC-MS/MS can equally be employed for the analysis of natural and synthetic hormones. - Herein are presented the results of the first international inter-laboratory study on determination of selected steroid hormones in environmental aqueous samples.

Extraction of hafnium by 1-phenyl-3-methyl-4-benzoyl-5-pyralozone from aqueous-alcoholic solutions

International Nuclear Information System (INIS)

Hala, J.; Prihoda, J.

1975-01-01

Extraction of hafnium by 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HL) in benzene, toluene, chloroform and tetrachloromethane from aqueous-alcoholic solutions of the formal acidity of 2M-HClO 4 was studied. Methyl, ethyl, n- and isopropyl, tert-butyl and allyl alcohol as well as ethylene glycol monomethyl ether and propylene glycol were used as organic components of the mixed aqueous-organic phase. Their presence in some cases resulted in a synergic increase in the distribution ratio of hafnium. The increase is interpreted using the results of a slope analysis and measurements of the alcohol distribution and the relative permittivity of the organic phase. It is suggested that HfL 4 molecules were solvated by alcohol molecules in the organic phase. At high alcohol concentration synergism changed into antagonism. This was caused by changes in the distribution of HL and its interaction with the alcohol in the organic phase. (author)

Influence of internal refractive index gradients on size measurements of spherically symmetric particles by phase Doppler anemometry.

Science.gov (United States)

Schneider, M; Hirleman, E D

1994-04-20

A model based on geometric optics for predicting the response of interferometric (phase Doppler) instruments for size measurements of particles with radially symmetric but inhomogeneous internal refractive index profiles is developed. The model and results are important for applications in which heat or mass transfer from the particles or droplets is significant, for example, in liquid-fuel combustion. To quantify the magnitude of potential bias errors introduced by the classical assumption of uniform internal properties on phase Doppler measurements, we compute calibration curves for a sequence of times during the evaporation of a decane droplet immersed in an environment of T = 2000 K and p = 10 bars. The results reveal considerable effects on the relation between phase difference and droplet diameter caused by the refractive index gradients present. The model provides an important tool to assess sizing uncertainties that can be expected when applying conventional (based on uniform properties) phase Doppler calibration curves in spray combustion and similar processes.

Impact of Surface Active Ionic Liquids on the Cloud Points of Nonionic Surfactants and the Formation of Aqueous Micellar Two-Phase Systems.

Science.gov (United States)

Vicente, Filipa A; Cardoso, Inês S; Sintra, Tânia E; Lemus, Jesus; Marques, Eduardo F; Ventura, Sónia P M; Coutinho, João A P

2017-09-21

Aqueous micellar two-phase systems (AMTPS) hold a large potential for cloud point extraction of biomolecules but are yet poorly studied and characterized, with few phase diagrams reported for these systems, hence limiting their use in extraction processes. This work reports a systematic investigation of the effect of different surface-active ionic liquids (SAILs)-covering a wide range of molecular properties-upon the clouding behavior of three nonionic Tergitol surfactants. Two different effects of the SAILs on the cloud points and mixed micelle size have been observed: ILs with a more hydrophilic character and lower critical packing parameter (CPP formation of smaller micelles and concomitantly increase the cloud points; in contrast, ILs with a more hydrophobic character and higher CPP (CPP ≥ 1) induce significant micellar growth and a decrease in the cloud points. The latter effect is particularly interesting and unusual for it was accepted that cloud point reduction is only induced by inorganic salts. The effects of nonionic surfactant concentration, SAIL concentration, pH, and micelle ζ potential are also studied and rationalized.

Electroviscous dissipation in aqueous electrolyte films with overlapping electric double layers

NARCIS (Netherlands)

Liu, Fei; Klaassen, Aram Harold; Zhao, Cunlu; Mugele, Friedrich Gunther; van den Ende, Henricus T.M.

2018-01-01

We use dynamic atomic force microscopy (AFM) to investigate the forces involved in squeezing out thin films of aqueous electrolyte between an AFM tip and silica substrates at variable pH and salt concentration. From amplitude and phase of the AFM signal we determine both conservative and dissipative

A new correlation for nucleate pool boiling of aqueous mixtures

International Nuclear Information System (INIS)

Thome, J.R.; Shakir, S.

1987-01-01

A new mixture boiling correlation was developed for nucleate pool boiling of aqueous mixtures on plain, smooth tubes. The semi-empirical correlation models the rise in the local bubble point temperature in a mixture caused by the preferential evaporation of the more volatile component during bubble growth. This rise varies from zero at low heat fluxes (where only single-phase natural convection is present) up to nearly the entire boiling range at the peak heat flux (where latent heat transport is dominant). The boiling range, which is the temperature difference between the dew point and bubble point of a mixture, is used to characterize phase equilibrium effects. An exponential term models the rise in the local bubble point temperature as a function of heat flux. The correlation was compared against binary mixture boiling data for ethanol-water, methanol-water, n-propanol-water, and acetone-water. The majority of the data was predicted to within 20%. Further experimental research is currently underway to obtain multicomponent boiling data for aqueous mixtures with up to five components and for wider boiling ranges

New selective ligands for caesium. Application to Cs+/Na+ separation by nano-filtration-complexation in aqueous phase

International Nuclear Information System (INIS)

Pellet-Rostaing, S.; Chitry, F.; Lemaire, M.; Guy, A.; Foos, J.

2000-01-01

Separating traces of caesium from aqueous medium containing high sodium concentration is a harsh problem because caesium and sodium have a similar behaviour in aqueous medium. The aim of our study was to select a highly caesium-selective ligand in a nano-filtration-complexation process in order to achieve Cs + /Na + separation. This process involve a nano-filtration step combined with a preliminary complexation step. Caesium complexes are retained by the nano-filtration membrane whereas free sodium cations pass through it. We tried to find a relation between the ligands structure and their activity towards caesium-complexation. Among the synthesized receptors, Tetra-hydroxylated bis-crown-6 calix[4]arene was found to be the more caesium-selective ligand (S=β(Cs + )/β(Na+)=6600). Combined with a nano-filtration process, this ligand helped reaching 90% caesium retention in a highly concentrated aqueous medium ([NaNO 3 ] = 3 mol/L). (authors)

ISOCHORIC HEAT CAPACITY OF 1% AQUEOUS SOLUTION OF MAGNESIUM CHLORIDE

Directory of Open Access Journals (Sweden)

V. I. Dvoryanchikov

2016-01-01

Full Text Available Aim. The aim is to conduct an experimental study of isochoric heat capacity of 1% aqueous solution of magnesium chloride along the phase boundary curve.Method. In order to determine the isochoric heat capacity at the phase boundary curve we used the adiabatic calorimeter of KH. I. Amirkhanov.Results. Results of the study of the isochoric heat capacity depending on the temperature are given in tables and figures; the findings are compared with those of other researchers. When evaluating a complex system, we ought not to evaluate its effectiveness on the basis of only one criterion, even a very important, in this case must take into account the requirements of the technical, economic, environmental and of other natures.Conclusions. When solving optimization problems of efficiency in geothermal energy it is necessary to take into account the fact of the temperature dependence of the heat and density. The temperature dependence of the density and heat capacity in the calculations significantly affect the value of the efficiency criterion to be taken into account, otherwise the calculation error can be up to 20%. The data obtained from the isochoric heat capacity of aqueous solutions of magnesium chloride is compared with the data for water and aqueous solutions of NaCl and NaOH, obtained previously, which may be represented as a model of geothermal and sea water.

Fiber Optic Microcantilever Sensor Coupled with Reactive Polymers for Vapor Phase Detection of Ammonia, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Luna Innovations proposes to adapt its current aqueous-based, fiber-optic microcantilever sensor technology for real-time, monitoring of ammonia in air. Phase I...

Bubble splitting under gas–liquid–liquid three-phase flow in a double T-junction microchannel

NARCIS (Netherlands)

Liu, Yanyan; Yue, Jun; Zhao, Shuainan; Yao, Chaoqun; Chen, Guangwen

Gas–aqueous liquid–oil three-phase flow was generated in a microchannel with a double T-junction. Under the squeezing of the dispersed aqueous phase at the second T-junction (T2), the splitting of bubbles generated from the first T-junction (T1) was investigated. During the bubble splitting process,

Aqueous actinide complexes: A thermochemical assessment

International Nuclear Information System (INIS)

Fuger, J.; Khodakovsky, I.L.; Medvedev, V.A.; Navratil, J.D.

1979-01-01

The scope and purpose of an assessment of the thermodynamic properties of the aqueous actinide complexes are presented. This work which, at present, is limited to inorganic ligands and three selected organic ligands (formate, acetate and oxalate), is part of an effort established by the International Atomic Energy Agency to assess the thermodynamic properties of the actinides and their compounds. The problems involved in this work are illustrated by discussing the present status of the assessment as related to a few complex species, (hydroxyl-, fluoride-, carbonate complexes). (orig.) [de

Fluoresence quenching of riboflavin in aqueous solution by methionin and cystein

International Nuclear Information System (INIS)

Droessler, P.; Holzer, W.; Penzkofer, A.; Hegemann, P.

2003-01-01

The fluorescence quantum distributions, fluorescence quantum yields, and fluorescence lifetimes of riboflavin in methanol, DMSO, water, and aqueous solutions of the sulphur atom containing amino acids methionin and cystein have been determined. In methanol, DMSO, and water (pH=4-8) only dynamic fluorescence reduction due to intersystem crossing and internal conversion is observed. In aqueous methionin solutions of pH=5.25-9 a pH independent static and dynamic fluorescence quenching occurs probably due to riboflavin anion-methionin cation pair formation. In aqueous cystein solutions (pH range from 4.15 to 9) the fluorescence quenching increases with rising pH due to cystein thiolate formation. The cystein thiol form present at low pH does not react with neutral riboflavin. Cystein thiolate present at high pH seems to react with neutral riboflavin causing riboflavin deprotonation (anion formation) by cystein thiolate reduction to the cystein thiol form

Enhanced Hydrothermal Stability and Catalytic Activity of La _x Zr _y O _z Mixed Oxides for the Ketonization of Acetic Acid in the Aqueous Condensed Phase

Energy Technology Data Exchange (ETDEWEB)

Lopez-Ruiz, Juan A. [Energy and Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States; Cooper, Alan R. [Energy and Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States; Li, Guosheng [Energy and Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States; Albrecht, Karl O. [Energy and Environment Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States

2017-08-24

Common ketonization catalysts such as ZrO2, CeO2, CexZryOz, and TiO2-based catalysts have been reported to lose surface area, undergo phase-transformation, and lose catalytic activity when utilized in the condensed aqueous phase. In this work, we synthesized and tested a series of LaxZryOz mixed metal oxides with different La:Zr atomic ratios with the goal of enhancing the catalytic activity and stability for the ketonization of acetic acid in condensed aqueous media at 568 K. We synthesized a hydrothermally stable LaxZryOz mixed-metal oxide catalyst with enhanced ketonization activities 360 and 40 times more active than La2O3 and ZrO2, respectively. Catalyst characterization techniques suggest that the formation of a hydrothermally stable catalyst which is isomorphic with tetragonal-ZrO2 under hydrothermal reaction conditions.

Process for plutonium rextraction in aqueous solution from an organic solvent, especially for uranium plutonium partition

International Nuclear Information System (INIS)

Germain, M.; Gillet, B.; Pasquiou, J.Y.

1989-01-01

The organic solvent containing plutonium is contacted with an aqueous solution of a uranous salt, for instance uranous nitrate, and a hydroxylamine salt, for instance the nitrate. In these conditions uranous nitrate is a reducing agent of Pu III and hydroxylamine nitrate stabilizes Pu III and U IV in the aqueous phase. Performances are similar to these of the U IV-hydrazine nitrate without interference of hydrazine nitrate degradation products [fr

Biodegradation of naphthalene from nonaqueous-phase liquids

International Nuclear Information System (INIS)

Ghoshal, S.; Luthy, R.G.; Ramaswami, A.

1995-01-01

Dissolution of polycyclic aromatic hydrocarbons (PAHs) from a non-aqueous-phase liquid (NAPL) to the aqueous phase renders these compounds bioavailable to microorganisms. Subsequent biodegradation of organic phase PAH then results in a depletion of PAH from the NAPL. This study focuses on identifying the rate-controlling processes affecting naphthalene biomineralization from a complex multicomponent NAPL, coal tar, and a simple two-component NAPL. A simplified dissolution degradation model is presented to identify quantitative criteria to assess whether mass transfer or biokinetic limitations control the overall rate of biotransformation of PAH compounds. Results show that the rate of mass transfer may control the overall rate of biotransformation in certain systems. Mass transfer does not limit biodegradation in slurry systems when coal tar is distributed in the micropores of a large number of small microporous silica particles. The end points of naphthalene degradation from the NAPLs have been evaluated, and results suggest that depletion of a significant mass of naphthalene from the NAPL phase is possible

Multiple solid-phase microextraction

NARCIS (Netherlands)

Koster, EHM; de Jong, GJ

2000-01-01

Theoretical aspects of multiple solid-phase microextraction are described and the principle is illustrated with the extraction of lidocaine from aqueous solutions. With multiple extraction under non-equilibrium conditions considerably less time is required in order to obtain an extraction yield that

Species dependent radiotracer study of Cr(VI) and Cr(III) using an aqueous biphasic system

Energy Technology Data Exchange (ETDEWEB)

Roy, K.; Lahiri, S. [Chemical Sciences Div., Saha Inst. of Nuclear Physics, Kolkata (India)

2008-07-01

The speciation study of Cr(III) and Cr(VI) was carried out using a polyethylene glycol (PEG) based aqueous biphasic extraction system (ABS). Neutron activated Cr(III) and Cr(VI) salts were assayed in a HPGe detector before and after employing aqueous biphasic extraction. Different salts of various salting out abilities were taken as the salt rich phase. The best condition for extraction of Cr(VI) and the maximum differential attitude of ABS to Cr(VI) and Cr(III) was observed when 2 M Na{sub 2}SO{sub 4} and PEG 4000 (50% w/w) solutions were used. Cr(III) can also be extracted by the PEG with prior complexation with diphenylthiocarbazone (dithizone). The chromium dithizonate complex is quantitatively extracted by the PEG rich phase. (orig.)

Aqueous-Based Fabrication of Low-VOC Nanostructured Block Copolymer Films as Potential Marine Antifouling Coatings.

Science.gov (United States)

Kim, Kris S; Gunari, Nikhil; MacNeil, Drew; Finlay, John; Callow, Maureen; Callow, James; Walker, Gilbert C

2016-08-10

The ability to fabricate nanostructured films by exploiting the phenomenon of microphase separation has made block copolymers an invaluable tool for a wide array of coating applications. Standard approaches to engineering nanodomains commonly involve the application of organic solvents, either through dissolution or annealing protocols, resulting in the release of volatile organic compounds (VOCs). In this paper, an aqueous-based method of fabricating low-VOC nanostructured block copolymer films is presented. The reported procedure allows for the phase transfer of water insoluble triblock copolymer, poly(styrene-block-2 vinylpyridine-block-ethylene oxide) (PS-b-P2VP-b-PEO), from a water immiscible phase to an aqueous environment with the assistance of a diblock copolymeric phase transfer agent, poly(styrene-block-ethylene oxide) (PS-b-PEO). Phase transfer into the aqueous phase results in self-assembly of PS-b-P2VP-b-PEO into core-shell-corona micelles, which are characterized by dynamic light scattering techniques. The films that result from coating the micellar solution onto Si/SiO2 surfaces exhibit nanoscale features that disrupt the ability of a model foulant, a zoospore of Ulva linza, to settle. The multilayered architecture consists of a pH-responsive P2VP-"shell" which can be stimulated to control the size of these features. The ability of these nanostructured thin films to resist protein adsorption and serve as potential marine antifouling coatings is supported through atomic force microscopy (AFM) and analysis of the settlement of Ulva linza zoospore. Field trials of the surfaces in a natural environment show the inhibition of macrofoulants for 1 month.